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Studies on the Propagation of the Freshwater Prawn, Macrobrachium nipponense (De Haan) Reared in the Laboratory 2. Life History and Seedling Production (담수산 새우, Macrobrachium nipponense (De Haan)의 증${\cdot}$양식에 관한 생물학적 기초연구 2. 생활사 및 종묘생산에 관한 연구)

  • KWON Chin-Soo;LEE Bok-Kyu
    • Journal of Aquaculture
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    • v.5 no.1
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    • pp.29-67
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    • 1992
  • Life cycle and seed production of the freshwater prawn, Macrobrachium nipponense, were studied and the results are as follows : 1. Larval development : Embryos hatched out as zoea larvae of 2.06 mm in mean body length. The larvae passed through 9 zoea stages in $15{\~}20$ days and then metamorphosed into postlarvae measuring 5.68 mm in mean body length. Each zoea stage can be identified based on the shapes of the first and second antennae, exo- and endopodites of the first and second pereiopods, telson and maxillae. 2. Environmental requirements of zoea larvae : Zoea larvae grew healthy when fed with Artemia nauplii. Metamorphosing rate was $65{\~}72{\%}$ at $26{\~}28\%$ and $7.85{\~}8.28\%_{\circ}Cl.$. The relationship between the zoeal period (Y in days) and water temperature (X in $^{\circ}C$) is expressed as Y=46.0900-0.9673X. Zoeas showed best survival in a water temperature range of $26{\~}32^{\circ}C$ (optimum temperature $28^{\circ}C$), at which the metamorphosing rate into postlarvae was $54{\~}72\%$ The zoeas survived more successfully in chlorinity range of $4.12{\~}14.08{\%_{\circ}}Cl.$, (optimum chlorinity $7.6{\~}11.6\;{\%_{\circ}}Cl.$.), at which the metamorphosing rate was $42{\~}76{\%}$. The whole zoeal stages tended to be longer in proportion as the chlorinity deviated from the optimum range and particularly toward high chlorinity. Zoeas at all stages could not tolerate in the freshwater. 3. Environmental requirements of postlarvae and juveniles : Postlarvae showed normal growth at water temperatures between $24{\~}32^{\circ}C$ (optimun temperature $26{\~}28^{\circ}$. The survival rate up to the juvenile stage was $41{\~}63{\%}$. Water temperatures below $24^{\circ}C$ and above $32^{\circ}$ resulted in lower growth, and postlarvae scarcely grew at below $17^{\circ}C$. Cannibalism tended to occur more frequently under optimum range of temperatures. The range of chlorinity for normal growth of postlarvae and juveniles was from 0.00 (freshwater) to $11.24{\%_{\circ}}Cl.$, at which the survival rate was $32{\~}35\%$. The postlarvae grew more successfully in low chlorinities, and the best growth was found at $0.00\~2.21{\%_{\circ}}Cl.$. The postlarvae and juveniles showed better growth in freshwater but did not survive in normal sea water. 4. Feeding effect of diet on zoea Ilarvae : Zoea larvae were successfully survived and metamorposed into postlarvae when fed commercial artificial plankton, rotifers, and Artemia nauplii in the aquaria. However, the zoea larvae that were fed Artemia nauplii and reared in Chlorella mixed green water showed better results. The rate of metamorphosis was $68\~{\%}75$. The larvae fed cow live powder, egg powder, and Chlorella alone did not survive. 5. Diets of postlarvae, juveniles and adults : Artemia nauplii and/or copepods were good food for postlarvae. Juveniles and adults were successfully fed fish or shellfish flesh, annelids, corn grain, pelleted feed along with viscera of domestic animals or fruits. 6. Growth of postlarvae, juveniles and adults : Under favorable conditions, postlarvae molted every five or six days and attained to the juvenile stage within two months and they reached 1.78 cm in body length and 0.17 g in body weight. The juveniles grew to 3.52 cm in body length and 1.07 g in body weight in about four months. Their sexes became determinable based on the appearance of male's rudimental processes (a secondary sex character) on the endopodites of second pereiopods of males. The males commonly reached sexual maturity in seven months after attaining the postlarvae stage and they grew to 5.65 cm in body length and 3.41 g in body weight. Whereas the females attained sexual maturity within six to seven months, when they measured 4.93 cm in body length and 2.43 g in body weight. Nine or ten months after hatching, the males grew $6.62{\~}7.14$ cm in body length and $6.68{\~}8.36$ g in body weight, while females became $5.58{\~}6.08$ cm and $4.04{\~}5.54$ g. 7. Stocking density : The maximum stocking density in aquaria for successful survival and growth was $60{\~}100$ individuals/$\ell$ for zoeas in 30-days rearing (survival rate to postlarvae, $73{\~}80{\%}$) ; $100{\~}300$ individuals/$m^2$ for postlarvae of 0.57 cm in body length (survival rate for 120 days, $78{\~}85{\%}$) ; $40{\~}60$ individuals/$m^2$ for juveniles of 2.72 cm in body length (survival rate for 120 days, $63{\~}90{\%}$) : $20{\~}40$ individuals/$m^2$ for young prawns of 5.2 cm in body length (survival rate for 120 days, $62\~90{\%}$) ; and $10\~30$ individuals/$m^2$ for adults of 6.1 cm in body length (survival rate for 60 days, $73\~100{\%}$). The stocking density of juveniles, youngs and adults could be increased up to twice by providing shelters.

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Matrix Metalloproteinase in Idiopathic Pulmonary Fibrosis (특발성 폐섬유화증환자의 기관지폐포세척액 및 폐포대식세포 배양액의 Matrix metalloproteinase의 변화)

  • Park, Joo-Hun;Shim, Tae-Sun;Lim, Chae-Man;Koh, Youn-Suck;Lee, Sang-Do;Kim, Woo-Sung;Kim, Won-Dong;Kim, Dong-Soon
    • Tuberculosis and Respiratory Diseases
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    • v.51 no.4
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    • pp.303-314
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    • 2001
  • Background : Matrix metalioproteinase(MMP)-2 and MMP-9 have been known to play an important role in cell migration and the tissue remodeling process by type IV collagen lysis, a major component of the basement membrane. Intra-alveolar fibrosis, secondary to an injury to the basement membrane of the alveolar epithelial lining, is a major process in the pathogenesis of idiopathic pulmonary fibrosis(IPF). Therefore, MMP-2 and MMP-9 was hypothesized to play an important role in IPF pathogenesis. As a result, their level may reflect the activity or prognosis. Method : Forty one progressive IPF patients(age $59.82{\pm}1.73$ years, M:F=23:18), 16 patients with stable IPF for more than one year without therapy(age : $63.6{\pm}2.8$ years, M:F=13:3), and 7 normal controls were enrolled in this study. The MMP-2 and MMP-9 levels in the BAL fluid and alveolar macrophage conditioned media(AM-CM) were measured by zymography and the TIMP-1 level was measured by ELISA. Results : 1) The MMP-2 level in BALF was highest in the progressive IPF group ($1.36{\pm}0.28$) followed by the stable group ($0.46{\pm}0.13$) and the controls ($0.08{\pm}0.09$), which was statistically significant. The MMP-9 level of the IPF ($0.31{\pm}0.058$) and the stable group ($0.22{\pm}0.078$) were higher than that of the control group ($0.002{\pm}0.004$). In the AM-CM, only MMP-9 was detected, which was significantly higher in IPF group ($0.80{\pm}0.1O$) than in the control group($0.23{\pm}0.081$). The TIMP-1 level was also higher in both the IPF ($36.34{\pm}8.62\;{\mu}g/ml$) and stable group ($20.83{\pm}8.53\;{\mu}g/ml$) compared to the control group ($2.80{\pm}1.05\;{\mu}g/ml$) (p<0.05). 3) There was a correlation between the MMP-2 level in the BALF with the total cell number(r=0.298) and neutrophils(r=0.357) (p<0.05), and the MMP-9 level with the number of neutrophils (r=0.407) and lymphocytes (r=0.574)(p<0.05). The TIMP-1 level correlated with the total number of cell (r=0.338, p<0.05) and neutrophils(r=0.449, p=0.059). Conclusion : Both MMP and TIMP appear to play an important role in IPF pathogenesis, and their level may reflect the disease activity.

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Consideration on Shielding Effect Based on Apron Wearing During Low-dose I-131 Administration (저용량 I-131 투여시 Apron 착용여부에 따른 차폐효과에 대한 고찰)

  • Kim, Ilsu;Kim, Hosin;Ryu, Hyeonggi;Kang, Yeongjik;Park, Suyoung;Kim, Seungchan;Lee, Guiwon
    • The Korean Journal of Nuclear Medicine Technology
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    • v.20 no.1
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    • pp.32-36
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    • 2016
  • Purpose In nuclear medicine examination, $^{131}I$ is widely used in nuclear medicine examination such as diagnosis, treatment, and others of thyroid cancer and other diseases. $^{131}I$ conducts examination and treatment through emission of ${\gamma}$ ray and ${\beta}^-$ ray. Since $^{131}I$ (364 keV) contains more energy compared to $^{99m}Tc$ (140 keV) although it displays high integrated rate and enables quick discharge through kidney, the objective of this study lies in comparing the difference in exposure dose of $^{131}I$ before and after wearing apron when handling $^{131}I$ with focus on 3 elements of external exposure protection that are distance, time, and shield in order to reduce the exposure to technicians in comparison with $^{99m}Tc$ during the handling and administration process. When wearing apron (in general, Pb 0.5 mm), $^{99m}Tc$ presents shield of over 90% but shielding effect of $^{131}I$ is relatively low as it is of high energy and there may be even more exposure due to influence of scattered ray (secondary) and bremsstrahlung in case of high dose. However, there is no special report or guideline for low dose (74 MBq) high energy thus quantitative analysis on exposure dose of technicians will be conducted based on apron wearing during the handling of $^{131}I$. Materials and Methods With patients who visited Department of Nuclear Medicine of our hospital for low dose $^{131}I$ administration for thyroid cancer and diagnosis for 7 months from Jun 2014 to Dec 2014 as its subject, total 6 pieces of TLD was attached to interior and exterior of apron placed on thyroid, chest, and testicle from preparation to administration. Then, radiation exposure dose from $^{131}I$ examination to administration was measured. Total procedure time was set as within 5 min per person including 3 min of explanation, 1 min of distribution, and 1 min of administration. In regards to TLD location selection, chest at which exposure dose is generally measured and thyroid and testicle with high sensitivity were selected. For preparation, 74 MBq of $^{131}I$ shall be distributed with the use of $2m{\ell}$ syringe and then it shall be distributed after making it into dose of $2m{\ell}$ though dilution with normal saline. When distributing $^{131}I$ and administering it to the patient, $100m{\ell}$ of water shall be put into a cup, distributed $^{131}I$ shall be diluted, and then oral administration to patients shall be conducted with the distance of 1m from the patient. The process of withdrawing $2m{\ell}$ syringe and cup used for oral administration was conducted while wearing apron and TLD. Apron and TLD were stored at storage room without influence of radiation exposure and the exposure dose was measured with request to Seoul Radiology Services. Results With the result of monthly accumulated exposure dose of TLD worn inside and outside of apron placed on thyroid, chest, and testicle during low dose $^{131}I$ examination during the research period divided by number of people, statistics processing was conducted with Wilcoxon Signed Rank Test using SPSS Version. 12.0K. As a result, it was revealed that there was no significant difference since all of thyroid (p = 0.345), chest (p = 0.686), and testicle (p = 0.715) were presented to be p > 0.05. Also, when converting the change in total exposure dose during research period into percentage, it was revealed to be -23.5%, -8.3%, and 19.0% for thyroid, chest, and testicle respectively. Conclusion As a result of conducting Wilcoxon Signed Rank Test, it was revealed that there is no statistically significant difference (p > 0.05). Also, in case of calculating shielding rate with accumulate exposure dose during 7 months, it was revealed that there is irregular change in exposure dose for inside and outside of apron. Although the degree of change seems to be high when it is expressed in percentage, it cannot be considered a big change since the unit of accumulated exposure dose is in decimal points. Therefore, regardless of wearing apron during high energy low dose $^{131}I$ administration, placing certain distance and terminating the administration as soon as possible would be of great assistance in reducing the exposure dose. Although this study restricted $^{131}I$ administration time to be within 5 min per person and distance for oral administration to be 1m, there was a shortcoming to acquire accurate result as there was insufficient number of N for statistics and it could be processed only through non-parametric method. Also, exposure dose per person during lose dose $^{131}I$ administration was measured with accumulated exposure dose using TLD rather than through direct-reading exposure dose thus more accurate result could be acquired when measurement is conducted using electronic dosimeter and pocket dosimeter.

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STUDIES ON THE DIMORPHISM AND FERTILITY OF PERSICARIA JAPONICA (MEISSNER) GROSS ET NAKAI (Persicaria Japonica (MISSNER) Gross et Nakai의 이형화와 수정력에 관한 연구)

  • HARN, Chang Yawl
    • Journal of Plant Biology
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    • v.3 no.1
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    • pp.1-15
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    • 1960
  • HARN, Chang Yawl : Studies on the dimorphism and Fertility of Persicaria japonica (MEISSNER) Gross et Nakai. Kor Jour. Bot. 3(I) 1-15 1960 Numerous investigations, since the works of DARWIN, have been made regarding the heterostylous plants by JOST (1907), CORRENS (1924), LAIBACK (1924), LEWIS (1943), and many others. Studies on the heterostylous Polygomum, however, were not reported except for the buckwhent, Fagopyrum esculentum, which was investigated by SCHOCH-BODMER (1930), EAST (1934), FROLOVA & Co-Workers (1946), MORRIS (1947, 1951) TATEBE (1949, 1951, 1953), present author (1957), and others. It is because no heterostylous species, besides buckwheat, have been known to exist in the Polygonum family. The author, during his studies on both heterostylism and fertility of Polygonaceae, has found that the species, persicaria japonica (Meissner) Gross et Nakai, is not diecious as has been known in taxonomy, but in reality beterostylous both morphologically and physiologically. It was found that this plant, regarded by taxonomist, as a male plant setting no seed, actually set seed (botanical fruit) when legitimate combination was made. Since his brief report on the dimorphic phenomens of this plant in 1956, the author's further research on the manner of fertilization has revealed that this species is a peculiar type whose dimorphism has undergone extreme specialization structurally and physiologically, the short-styled individual behaving in nature as a male plant and the long-styled individual, as female, whereas in controllled pollination the plant shows highly differentiated typical dimorphism. When compared with the other dimorphous species of this family, F. esculentum and P. sentiosa. it has been clarified that these three species differ in the degree of differentiation of their dimorphism morphologically and physiologically. That is, P. japonica has developed such a high specialization as to mislead the taxonomists, while P. senticosa shows almost no noticeable difference between long- and shortstyled individuals retaining most of the inherent physiological character cmmon to the genus except for the fact that it has two forms of flowers. F. esculentum appears to have taken the intermediate position in every respect. The result obtained in the present experiment are summarized as follows: 1) P. japonica has two kinds of individuals, one long style-short stamened; the other, short style-long stamened. The floral structure of this plants shows typical characteristics of dimorphic heterostylism. The differentiation between the two forms of flower has proceeded so highly both in primary and secondary difference of flower structure that this may be regarded as the most specialized form of dimorphism. 2) The differences of floral structure between the long and short styled individuals are remarkable compared with the other dimorphic species of the family. 3) The stamens of long styled plants show the sign of deteriolation whereas those of the short styled flower are well-developed. 4) When legitimate combinations are made, both L- and S-styled individuals are fertilized well and set seed (fruit), while in the illegitimate combination no fertilization and seed setting occur. Physiologically this species exhibits the typical behavior of dimorphic plants. 5) The self-fertile character, so common in other species of the other non-heterostyle Polygonum family, has disappeared completely. 6) Under natural conditions, no or few seed setting is observed in short styled individuals that behave as if they were male plants. 7) In hand pollination, the combination of both $L{\times}S$ and $S{\times}L$ alike yield relatively good fertility and seed-formation, the behavior of short styled individuals in artificial pollination differing remarkably from that in nature. 8) Under controlled pollination, $L{\times}S$ combination sets far more seed than in the combination of $S{\times}L$. In the S-styled individuals, the fertilized flower has the tendency of its seed more readily falling off in every stage of seed development than in the L-styled individuals. 9) The behaviors of pollen tubes just parallels the results of fertility test. That is, in the illegitimate combination, L-selfed, $L{\times}L$, S-selfed, and $S{\times}S$, the growth of pollen tubes is checked in the style, while in legitimately combined $L{\times}S$ and $S{\times}L$, the pollen tubes grow well reaching the ovaries within 40-50 minutes after pollination. The response of short styled individuals, known as male plant among taxonomists, is identical, as far as behavior fo pollen tube growth and fertilization are concerned, to that of long styled individuals, the so-called female plant. 10) The pollen grains from the short-styled plants are complete and fertile, whereas 70% of those of L-styled are found to be abortive, i.e., empty contents. 11) The remaining 30% of pollen of L-plant shows varied degree of stainability when stained with iron-aceto-carmine......mostly light red, while the pollen grains of S-style individuals are dark brown indicating complete fertility and viability. 12) The abundance of sterile pollen in L-styled and the nature of seed-dropping which occurs in S-styled individuals appear to be the main causes why the short styled individuals bear no seed in nature. Under controlled legitimate union, $S{\times}L$, the careful and elaborate pollination would give the S-styoled flowers the opportunities to receive the fertile pollens, though few in number, from L-styled plant, thus enabling S-plant to bear seed. 13) This species is not dioecious as is regarded by taxonomists, but typical dimorphic plant which has so highly specialized in floral structures and funcitons that the long-styled plant behaves just like a female individual; and the short-styled, like a male.

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Physiological and Ecological Studies on the Low Temperature Damages of Rice (Oryza sativia L.) (수도의 저온장해에 관한 생리 생태학적 연구)

  • 오윤진
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.26 no.1
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    • pp.1-31
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    • 1981
  • Experiments were conducted to investigate rice varietal response to low water and air temperatures at different growth stages from 1975 to 1980 in a phytotron in Suweon and in a cold water nursery in Chooncheon. Germination ability, seedling growth, sterility of laspikelets, panicle exertion, discoloration of leaves, and delay of heading of recently developed indica/japonica cross(I/J), japonica, and indica varieties at low air temperature or cold water were compared to those at normal temperature or natural conditions. The results are summarized as follows: 1. Practically acceptable germination rate of 70% was obtained in 10 days after initiation of germination test at 15\circ_C for japonica varieties, but 15 days for IxJ varieties. Varietal differences in germination ability at suboptimal temperature was greatest at 16\circ_C for 6 days. 2. Cold injury of rice seedlings was most severe at the 3.0-and 3.5-leaf stage and it was reduced as growth stage advanced. A significant positive correlation was observed between cold injury at 3-leaf stage and 6-leaf stage. 3. At day/night temperatures of 15/10\circ_C seedlings of both japonica and I/J varieties were dead in 42 days. At 20/15\circ_C japonica varieties produced tillers actively, but tillering of I/J varieties was retarded a little. At 25/15\circ_C, both japonica and I/J varieties produced tillers most actively. Increase in plant height was proportional to the increase in all varieties. 4. In I/J varieties the number of differentiated panicle rachis branches and spikelets was reduced at a day-night temperature of 20-15\circ_C compared to 25-20 or 30-25\circ_C, but not in japonica varieties although panicle exertion was retarded at 20-15\circ_C. The number of spikelets was not correlated with the number of primary rachis branches, but positively correlated with that of secondary rachis branches. 5. Heading of rice varieties treated with 15\circ_C air temperature at meiotic stage was delayed compared to that at tillering stage by 1-3 days and heading was delayed as duration of low temperature treatment increased. 6. At cold water treatment of 17\circ_C from tillering to heading stage, heading of japonica, I/J, and cold tolerant indica varieties was delayed 2-6, 3-9, and 4-5 days, respectively, Growth stage sensitive to delay of heading delay at water treatment were tillering stage, meiotic stage, and booting tage in that order, delay of heading was greater in indica corssed japonica(Suweon 264), japonica(Suweon 235), and cold tolerant indica(Lengkwang) varieties in that order. Delay of heading due to cold water treatment was positively correlated with culm length reduction and spikelet sterility. 7. Elongation of culms and exertion of panicles of rice varieties treated with low air temperature 17\circ_C. Culm length reduction rate of tall varieties was lower than that of short statured varieties at low temperature. Panicle exertion was most severaly retarded with low temperature treatment at heading stage. Generally, retardation of panicle exertion of 1/1 varieties was more severe than that of japonica varieties at low temperature. There was a positive correlation between panicle exertion and culm length at low temperature. 8. The number of panicles was increased with cold water treatment at tillering stage, but reduced at meiotic stage. As time of cold water treatment was conducted at earlier growth stage, culm length was shorter and panicle exertion poorer. 9. Sterility of all rice varieties was negligible at 17\circ_C for three days but 30.3-85.2% of strility was observed for nine-day treatment at 17\circ_C. Among the tested varieties, sterility of Suweon 264 and Milyang 42 was highest and that of Suweon 290 and Suweon 287 was lowest. The most sensitive growth stage to low temperature induced sterility was from 15 to 5 days before heading. There was positive correlation between sterility of rice plants treated with low temperature at meiotic and heading stage. 10. Percentage of spikelet sterility was greatest at cold water treatment at meiotic stage (auricle distance -15~-10cm) and it was higher in 1/1 (Suweon 264, Joseng tongil), japonica (Nongbaek, Towada), and cold tolerance indica(Lengkwang) varieties in the order. Level of cold water and position of young-ear affected on the sterility of varieties at meiotic stage; percentage of spikelet sterility of variety, Lengkwang, of which young-ear was located above the cold water level was high, but that of short statured variety, Suweon 264, of which young-ear was located in the cold water was lower. 11. Percentage of ripened grains was not reducted at 15\circ_C air temperature for three days at full heading stage in all varieties. However, at six-day low temperature treatment Suweon 287, Suweon 264 showed percentage of ripended grains lower than 60%, but at nine-day low temperature treatment all varieties showed percentage of ripened grains lower than 60%. Low temperature treatment of 17\circ_C from 10 days after heading for 20 days did not affect on the ripening of all varieties. 12. Uptake of nitrogen, phosphorous, potassium, calcium, and magnesium in whole plants was higher at average air temperature of 25\circ_C, but concentration of the elements was lower compared to those at 19\circ_C. However, both total uptake and concentration of manganese were higher at 19\circ_C compared to 25\circ_C. 13. Higher application of nitrogen, phosphorus, silicate, and compost increased yield of rice due to increased number of panicles and spike let fertility in cold water irrigated paddy.

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Dynamical Study on the Blasting with One-Free-Face to Utilize AN-FO Explosives (초유폭약류(硝油爆藥類)를 활용(活用)한 단일자유면발파(單一自由面發破)의 역학적(力學的) 연구(硏究))

  • Huh, Ginn
    • Economic and Environmental Geology
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    • v.5 no.4
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    • pp.187-209
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    • 1972
  • Drilling position is one of the most important factors affecting on the blasting effects. There has been many reports on several blasting factors of burn-cut by Messrs. Brown and Cook, but in this study the author tried to compare drilling positions of burn-cut to pyramid-cut, and also to correlate burn-cut effects of drilling patterns, not being dealt by Prof. Ito in his theory, which emphasized on dynamical stress analysis between explosion and free face. According to former theories, there break out additional tensile stress reflected at the free face supplemented to primary compressive stress on the blasting with one-free-face. But with these experimented new drilling patterns of burn-cut, more free faces and nearer distance of each drilling holes make blasting effects greater than any other methods. To promote the above explosive effect rationary, it has to be considered two important categories under-mentioned. First, unloaded hole in the key holes should be drilled in wider diameter possibly so that it breaks out greater stress relief. Second, key holes possibly should have closer distances each other to result clean blasting. These two important factors derived from experiments with, theories of that the larger the dia of the unloaded hole, it can be allowed wider secondary free faces and closes distances of each holes make more developed stress relief, between loaded and unloaded holes. It was suggested that most ideal distance between holes is about 4 clearance in U. S. A., but the author, according to the experiments, it results that the less distance allow, the more effective blasting with increased broken rock volume and longer drifted length can be accomplished. Developed large hole burn-cut method aimed to increase drifting length technically under the above considerations, and progressive success resulted to achieve maximum 7 blasting cycles per day with 3.1m drifting length per cycle. This achievement originated high-speed-drifting works, and it was also proven that application of Metallic AN-FO on large hole burn-cut method overcomes resistance of one-free-face. AN-FO which was favored with low price and safety handling is the mixture of the fertilizer or industrial Ammonium-Nitrate and fuel oil, and it is also experienced that it shows insensible property before the initiation, but once it is initiated by the booster, it has equal explosive power of Ammonium Nitrate Explosives (ANE). There was many reports about AN-FO. On AN-FO mixing ratio, according to these experiments, prowdered AN-FO, 93.5 : 6.5 and prilled AN-FO 94 : 6, are the best ratios. Detonation, shock, and friction sensities are all more insensitive than any other explosives. Residual gas is not toxic, too. On initation and propagation of the detonation test, prilled AN-FO is more effective than powered AN-FO. AN-FO has the best explosion power at 7 days elapsed after it has mixed. While AN-FO was used at open pit in past years prior to other conditions, the author developed new improved explosives, Metallic AN-FO and Underwater explosive, based on the experiments of these fundmental characteristics by study on its usage utilizing AN-FO. Metallic AN-FO is the mixture of AN-FO and Al, Fe-Si powder, and Underwater explosive is made from usual explosive and AN-FO. The explanations about them are described in the other paper. In this study, it is confirmed that the blasting effects of utilizing AN-FO explosives are very good.

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National Survey of Mycobacterial Diseases Other Than Tuberculosis in Korea (비결핵항산균증 전국 실태조사)

  • 대한결핵 및 호흡기학회 학술위원회
    • Tuberculosis and Respiratory Diseases
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    • v.42 no.3
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    • pp.277-294
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    • 1995
  • Background: The prevalence of tuberculosis in Korea decreased remarkably for the past 30 years, while the incidence of disease caused by mycobacteria other than tuberculosis is unknown. Korean Academy of Tuberculosis and Respiratory Diseases performed national survey to estimate the incidence of mycobacterial diseases other than tuberculosis in Korea. We analyzed the clinical data of confirmed cases for the practice of primary care physicians and pulmonary specialists. Methods: The period of study was from January 1981 to October 1994. We collected the data retrospectively by correspondence with physicians in the hospitals that referred the specimens to Korean Institute of Tuberculosis, The Korean National Tuberculosis Association for the detection of mycobacteria other than tuberculosis. In confirmed cases, we obtained the records for clinical, laboratory and radiological findings in detail using protocols. Results: 1) Mycobacterial diseases other than tuberculosis were confirmed that 1 case was in 1981, 2 cases in 1982, 4 cases in 1983, 2 cases in 1984, 5 cases in 1985, 1 case in 1986, 3 cases in 1987, 1 case in 1988, 6 cases in 1989, 9 cases in 1990, 14 cases in 1990, 10 cases in 1992, 4 cases in 1993, and 96 cases in 1994. Cases since 1990 were 133 cases(84.2%) of a total. 2) Fifty seven percent of patients were in the age group of over 60 years. The ratio of male to female patients was 2.6:1. 3) The distribution of hospitals in Korea showed that 61 cases(38.6%) were referred from Double Cross Clinic, 42 cases(26.6%) from health centers, 21 cases(13.3%) from tertiary referral hospitals, 15 cases(9.5%) from secondary referral hospitals, and 10 cases(6.3%) from primary care hospitals. The area distribution in Korea revealed that 98 cases(62%) were in Seoul, 17 cases(10.8%) in Gyeongsangbuk-do, 12 cases(7.6%) in Kyongki-do, 8 cases(5.1%) in Chungchongnam-do, each 5 cases(3.2%) in Gyeongsangnam-do and Chungchongbuk-do, 6 cases(3.8%) in other areas. 4) In the species of isolated mycobacteria other than tuberculosis, M. avium-intracellulare was found in 104 cases(65.2%), M. fortuitum in 20 cases(12.7%), M. chelonae in 15 cases(9.5%), M. gordonae in 7 cases(4.4%), M. terrae in 5 cases(3.2%), M. scrofulaceum in 3 cases(1.9%), M. kansasii and M. szulgai in each 2 cases(1.3%), and M. avium-intracellulare coexisting with M. terrae in 1 case(0.6%). 5) In pre-existing pulmonary diseases, pulmonary tuberculosis was 113 cases(71.5%), bronchiectasis 6 cases(3.8%), chronic bronchitis 10 cases(6.3%), and pulmonary fibrosis 6 cases(3.8%). The timing of diagnosis as having pulmonary tuberculosis was within 1 year in 7 cases(6.2%), 2~5 years ago in 32 cases(28.3%), 6~10 years ago in 29 cases(25.7%), 11~15 years ago in 16 cases(14.2%), 16~20 years ago in 15 cases (13.3%), and 20 years ago in 14 cases(12.4%). Duration of anti-tuberculous treatment was within 3 months in 6 cases(5.3%), 4~6 months in 17 cases(15%), 7~9 months in 16 cases(14.2%), 10~12 months in 11 cases(9.7%), 1~2 years in 21 cases(18.6%), and over 2 years in 8 cases(7.1%). The results of treatment were cure in 44 cases(27.9%) and failure in 25 cases(15.8%). 6) Associated extra-pulmonary diseases were chronic liver disease coexisting with chronic renal failure in 1 case(0.6%), diabetes mellitus in 9 cases(5.7%), cardiovascular diseases in 2 cases(1.3%), long-term therapy with steroid in 2 cases(1.3%) and chronic liver disease, chronic renal failure, colitis and pneumoconiosis in each 1 case(0.6%). 7) The clinical presentations of mycobacterial diseases other than tuberculosis were 86 cases (54.4%) of chronic pulmonary infections, 1 case(0.6%) of cervical or other site lymphadenitis, 3 cases(1.9%) of endobronchial tuberculosis, and 1 case(0.6%) of intestinal tuberculosis. 8) The symptoms of patients were cough(62%), sputum(61.4%), dyspnea(30.4%), hemoptysis or blood-tinged sputum(20.9%), weight loss(13.3%), fever(6.3%), and others(4.4%). 9) Smear negative with culture negative cases were 24 cases(15.2%) in first examination, 27 cases(17.1%) in second one, 22 cases(13.9%) in third one, and 17 cases(10.8%) in fourth one. Smear negative with culture positive cases were 59 cases(37.3%) in first examination, 36 cases (22.8%) in second one, 24 cases(15.2%) in third one, and 23 cases(14.6%) in fourth one. Smear positive with culture negative cases were 1 case(0.6%) in first examination, 4 cases(2.5%) in second one, 1 case (0.6%) in third one, and 2 cases(1.3%) in fourth one. Smear positive with culture positive cases were 48 cases(30.4%) in first examination, 34 cases(21.5%) in second one, 34 cases(21.5%) in third one, and 22 cases(13.9%) in fourth one. 10) The specimens isolated mycobacteria other than tuberculosis were sputum in 143 cases (90.5%), sputum and bronchial washing in 4 cases(2.5%), bronchial washing in 1 case(0.6%). 11) Drug resistance against all species of mycobacteria other than tuberculosis were that INH was 62%, EMB 55.7%, RMP 52.5%, PZA 34.8%, OFX 29.1%, SM 36.7%, KM 27.2%, TUM 24.1%, CS 23.4%, TH 34.2%, and PAS 44.9%. Drug resistance against M. avium-intracellulare were that INH was 62.5%, EMB 59.6%, RMP 51.9%, PZA 29.8%, OFX 33.7%, SM 30.8%, KM 20.2%, TUM 17.3%, CS 14.4%, TH 31.7%, and PAS 38.5%. Drug resistance against M. chelonae were that INH was 66.7%, EMB 66.7%, RMP 66.7%, PZA 40%, OFX 26.7%, SM 66.7%, KM 53.3%, TUM 53.3%, CS 60%, TH 53.3%, and PAS 66.7%. Drug resistance against M. fortuitum were that INH was 65%, EMB 55%, RMP 65%, PZA 50%, OFX 25%, SM 55%, KM 45%, TUM 55%, CS 65%, TH 45%, and PAS 60%. 12) The activities of disease on chest roentgenogram showed that no active disease was 7 cases(4.4%), mild 20 cases(12.7%), moderate 67 cases(42.4%), and severe 47 cases(29.8%). Cavities were found in 43 cases(27.2%) and pleurisy in 18 cases(11.4%). 13) Treatment of mycobacterial diseases other than tuberculosis was done in 129 cases(81.7%). In cases treated with the first line anti-tuberculous drugs, combination chemotherapy including INH and RMP was done in 86 cases(66.7%), INH or RMP in 30 cases(23.3%), and not including INH and RMP in 9 cases(7%). In 65 cases treated with the second line anti-tuberculous drugs, combination chemotherapy including below 2 drugs were in 2 cases(3.1%), 3 drugs in 15 cases(23.1%), 4 drugs in 20 cases(30.8%), 5 drugs in 9 cases(13.8%), and over 6 drugs in 19 cases (29.2%). The results of treatment were improvement in 36 cases(27.9%), no interval changes in 65 cases(50.4%), aggravation in 4 cases(3.1%), and death in 4 cases(3.1%). In improved 36 cases, 34 cases(94.4%) attained negative conversion of mycobacteria other than tuberculosis on cultures. The timing in attaining negative conversion on cultures was within 1 month in 2 cases(1.3%), within 3 months in 11 cases(7%), within 6 months in 14 eases(8.9%), within 1 year in 2 cases(1.3%) and over 1 year in 1 case(0.6%). Conclusion: Clinical, laboratory and radiological findings of mycobacterial diseases other than tuberculosis were summarized. This collected datas will assist in the more detection of mycobacterial diseases other than tuberculosis in Korea in near future.

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A Study on the Costume Style of Civil Servants' Stone Images Erected at Tombs of the Kings for Yi-dynasty (조선왕조(朝鮮王朝) 왕릉(王陵) 문인석상(文人石像)의 복식형태(服飾形態)에 관한 연구)

  • Kwon, Yong-Ok
    • Journal of the Korean Society of Costume
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    • v.4
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    • pp.87-114
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    • 1981
  • A costume reveals the social characteristics of the era in which it is worn, thus we can say that the history of change of the costume is the history of change of the living culture of the era. Since the Three States era, the costume structure of this country had been affected by the costume system of the China's historical dynasties in the form of the grant therefrom because of geographical conditions, which affection was conspicuous for the bureaucrat class, particularly including but not limited to the Kings' familities. Such a grant of the costume for the bureaucrat class (i.e., official uniform) was first given by the Dang-dynasty at the age of Queen Jinduck, the 28th of the Shilla-dynasty. Since then, the costume for the bureaucrats had consecutively been affected as the ages had gone from the unified Shilla, to the Koryo and to the Yi-dynasty. As the full costumes officially used by government officials (generally called "Baek Gwan") in the Yidynasty, there existed Jo-bok, Gong-bok and Sang-bok. Of such official costumes, Gong-bok was worn at the time of conducting official affairs of the dynasty, making a respectful visit for the expression of thanks or meeting diplomatic missions of foreign countries. It appears no study was made yet with regard to the Gong-bok while the studies on the Jo-bok and the Sangbok were made. Therefore, this article is, by rendering a study and research on the styles of costumes of civil servants' stone images erected at the Kings' tombs of the Yi-dynasty, to help the persons concerned understand the Gong-bok, one of the official costume for Baek Kwan of that age and further purports to specifically identify the styles and changes of the Gong-bok, worn by Baek Gwan during the Yi-dynasty, consisting of the Bok-doo (a hat, four angled and two storied with flat top), Po (gown), Dae (belt), and Hol (small and thin plate which was officially held by the government officials in hand, showing the courtesy to and writing brief memorandums before the King) and Hwa (shoes). For that purpose, I investigated by actually visiting the tombs of the Kings of the Yi-dynasty including the Geonwon-neung, the tomb of the first King Tae-jo and the You-neung, the tomb of the 27th King Soon-jong as well as the tombs of the lawful wives and concubines of various Kings, totalling 29 tombs and made reference to relevant books and records. Pursuant. to this study, of the 29 Kings' tombs the costume styles of civil servants' stone images erected at the 26 Kings' tombs are those of Gong-bok for Baek-gwan of the Yi-dynasty wearing Bok-doo as a hat and Ban-ryeong or Dan-ryenog Po as a gown with Dae, holding Hol in hand and wearing shoes. Other than those of the 26 tombs, the costume styles of the Ryu-neung, the tomb of the Moon-jo who was the first son of 23rd King Soon-jo and given the King's title after he died and of the You-neung, the tomb of the 27th King Soon-jong are those of Jobok with Yang-gwan (a sort of hat having stripes erected, which is different from the Bok-doo), and that of the Hong-neung, the tomb of the 26th King Go-jong shows an exceptional one wearing Yang-gwan and Ban-ryeong Po ; these costume styles other than Gongbok remain as the subject for further study. Gong-bok which is the costume style of civil servants' stone images of most of the Kings' tombs had not been changed in its basic structure for about 500 years of the Yi-dynasty and Koryo categorized by the class of officials pursuant to the color of Po and materials of Dae and Hol. Summary of this costume style follows: (1) Gwan-mo (hat). The Gwan-mo style of civil servants' stone images of the 26 Kings' tombs, other than Ryu-neung, Hong-neung and You-neung which have Yang-gwan, out of the 29 Kings' tombs of the Yi-dynasty reveals the Bok-doo with four angled top, having fore-part and back-part divided. Back part of the Bok-doo is double the fore-part in height. The expression of the Gak (wings of the Bokdoo) varies: the Gyo-gak Bok-doo in that the Gaks, roundly arisen to the direction of the top, are clossed each other (tombs of the Kings Tae-jong), the downward style Jeon-gak Bok-doo in that soft Gaks are hanged on the shoulders (tombs of the Kings Joong-jong and Seong-jong) and another types of Jeon-gak Bok-doo having Gaks which arearisen steeply or roundly to the direction of top and the end of which are treated in a rounded or straight line form. At the lower edge one protrusive line distinctly reveals. Exceptionally, there reveals 11 Yang-gwan (gwan having 11 stripes erected) at the Ryu-neung of the King Moon-jo, 9 Yang-gwan at the Hong-neung of the King Go-jong and 11 Yang-gwan at the You-neung of the King Soon-jong; noting that the Yang-gwan of Baek Kwan, granted by the Myeong-dynasty of the China during the Yi-dynasty, was in the shape of 5 Yang-gwan for the first Poom (class) based on the principle of "Yideung Chaegang" (gradual degrading for secondary level), the above-mentioned Yang-gwans are very contrary to the principle and I do not touch such issue in this study, leaving for further study. (2) Po (gown). (a) Git (collar). Collar style of Po was the Ban-ryeong (round collar) having small neck-line in the early stage and was changed to the Dan-ryeong (round collar having deep neck-line) in the middle of the: dynasty. In the Dan-ryeong style of the middle era (shown at the tomb of the King Young-jo); a, thin line such as bias is shown around the internal side edge and the width of collar became wide a little. It is particularly noted that the Ryu-neung established in the middle stage and the You-neung in the later stage show civil servants in Jo-bok with the the Jikryeong (straight collar) Po and in case of the Hong-neung, the Hong-neung, the tomb of the King Go-jong, civil servants, although they wear Yang-gwan, are in the Ban-ryeong Po with Hoo-soo (back embroidery) and Dae and wear shoes as used in the Jo-bok style. As I could not make clear the theoretical basis of why the civil servants' costume styles revealed, at these tombs of the Kings are different from those of other tombs, I left this issue for further study. It is also noted that all the civil servants' stone images show the shape of triangled collar which is revealed over the Godae-git of Po. This triangled collar, I believe, would be the collar of the Cheomri which was worn in the middle of the Po and the underwear, (b) Sleeve. The sleeve was in the Gwan-soo (wide sleeve) style. having the width of over 100 centimeter from the early stage to the later stage arid in the Doo-ri sleeve style having the edge slightly rounded and we can recognize that it was the long sleeve in view of block fold shaped protrusive line, expressed on the arms. At the age of the King Young-jo, the sleeve-end became slightly narrow and as a result, the lower line of the sleeve were shaped curved. We can see another shape of narrow sleeve inside the wide sleeve-end, which should be the sleeve of the Cheom-ri worn under the Gong-bok. (c) Moo. The Moo revealed on the Po of civil servants' stone images at the age of the King Sook-jong' coming to the middle era. Initially the top of the Moo was expressed flat but the Moo was gradually changed to the triangled shape with the acute top. In certain cases, top or lower part of the Moo are not reveald because of wear and tear. (d) Yeomim. Yeomim (folding) of the Po was first expressed on civil servants' stone images of the Won-neung, the tomb of the King Young-jo and we can seemore delicate expression of the Yeomim and Goreum (stripe folding and fixing the lapel of the Po) at the tomb of the Jeongseong-wanghoo, the wife of the King Young-jo, At the age of the King Soon-jo, we can see the shape of Goreum similar to a string rather than the Goreum and the upper part of the Goreum which fixes Yeomim was expressed on the right sleeve. (3) Dae. Dae fixed on the Po was placed half of the length of Po from the shoulders in the early stage. Thereafter, at the age of the King Hyeon-jong it was shown on the slightly upper part. placed around one third of the length of Po. With regard to the design of Dae, all the civil servants' stone images of the Kings' tombs other than those of the Geonwon-neung of the King Tae-jo show single or double protrusive line expressed at the edge of Dae and in the middle of such lines, cloud pattern, dangcho (a grass) pattern, chrysanthemum pattern or other various types of flowery patterns were designed. Remaining portion of the waist Dae was hanged up on the back, which was initially expressed as directed from the left to the right but thereafter expressed. without orderly fashion,. to the direction of the left from the right and vice versa, Dae was in the shape of Yaja Dae. In this regard, an issue of when or where such a disorderly fashion of the direction of the remaining portion of waist Dae was originated is also presented to be clarified. In case of the Ryuneung, Hong-neung and You-neung which have civil servants' stone images wearing exceptional costume (Jo-bok), waist Dae of the Ryu-neung and Hong-neung are designed in the mixture of dual cranes pattern, cosecutive beaded pattern and chrvsenthemum pattern and that of You-neung is designed in cloud pattern. (4) Hol. Although materials of the Hol held in hand of civil servants' stone images are not identifiable, those should be the ivory Hol as all the Baek Gwan's erected as stone images should be high class officials. In the styles, no significant changes were found, however the Hol's expressed on civil servants' stone images of the Yi-dynasty were shaped in round top and angled bottom or round top and bottom. Parcicularly, at the age of the King Young-jo the Hol was expressed in the peculiar type with four angles all cut off. (5) Hwa (shoes). As the shoes expressed on civil servants' stone images are covered with the lower edges of the Po, the styles thereof are not exactly identifiable. However, reading the statement "black leather shoes for the first class (1 Poom) to ninth class (9 Poom)," recorded in the Gyeongkook Daejon, we can believe that the shoes were worn. As the age went on, the front tips of the shoes were soared and particularly, at the Hong-neung of the King Go-jong the shoes were obviously expressed with modern sense as the country were civilized.

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The lesson From Korean War (한국전쟁의 교훈과 대비 -병력수(兵力數) 및 부대수(部隊數)를 중심으로-)

  • Yoon, Il-Young
    • Journal of National Security and Military Science
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    • s.8
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    • pp.49-168
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    • 2010
  • Just before the Korean War, the total number of the North Korean troops was 198,380, while that of the ROK(Republic of Korea) army troops 105,752. That is, the total number of the ROK army troops at that time was 53.3% of the total number of the North Korean army. As of December 2008, the total number of the North Korean troops is estimated to be 1,190,000, while that of the ROK troops is 655,000, so the ROK army maintains 55.04% of the total number of the North Korean troops. If the ROK army continues to reduce its troops according to [Military Reform Plan 2020], the total number of its troops will be 517,000 m 2020. If North Korea maintains the current status(l,190,000 troops), the number of the ROK troops will be 43.4% of the North Korean army. In terms of units, just before the Korean War, the number of the ROK army divisions and regiments was 80% and 44.8% of North Korean army. As of December 2008, North Korea maintains 86 divisions and 69 regiments. Compared to the North Korean army, the ROK army maintains 46 Divisions (53.4% of North Korean army) and 15 regiments (21.3% of North Korean army). If the ROK army continue to reduce the military units according to [Military Reform Plan 2020], the number of ROK army divisions will be 28(13 Active Division, 4 Mobilization Divisions and 11 Local Reserve Divisions), while that of the North Korean army will be 86 in 2020. In that case, the number of divisions of the ROK army will be 32.5% of North Korean army. During the Korean war, North Korea suddenly invaded the Republic of Korea and occupied its capital 3 days after the war began. At that time, the ROK army maintained 80% of army divisions, compared to the North Korean army. The lesson to be learned from this is that, if the ROK army is forced to disperse its divisions because of the simultaneous invasion of North Korea and attack of guerrillas in home front areas, the Republic of Korea can be in a serious military danger, even though it maintains 80% of military divisions of North Korea. If the ROK army promotes the plans in [Military Reform Plan 2020], the number of military units of the ROK army will be 32.5% of that of the North Korean army. This ratio is 2.4 times lower than that of the time when the Korean war began, and in this case, 90% of total military power should be placed in the DMZ area. If 90% of military power is placed in the DMZ area, few troops will be left for the defense of home front. In addition, if the ROK army continues to reduce the troops, it can allow North Korea to have asymmetrical superiority in military force and it will eventually exert negative influence on the stability and peace of the Korean peninsular. On the other hand, it should be reminded that, during the Korean War, the Republic of Korea was attacked by North Korea, though it kept 53.3% of troops, compared to North Korea. It should also be reminded that, as of 2008, the ROK army is defending its territory with the troops 55.04% of North Korea. Moreover, the national defense is assisted by 25,120 troops of the US Forces in Korea. In case the total number of the ROK troops falls below 43.4% of the North Korean army, it may cause social unrest about the national security and may lead North Korea's misjudgement. Besides, according to Lanchester strategy, the party with weaker military power (60% compared to the party with stronger military power) has the 4.1% of winning possibility. Therefore, if we consider the fact that the total number of the ROK army troops is 55.04% of that of the North Korean army, the winning possibility of the ROK army is not higher than 4.1%. If the total number of ROK troops is reduced to 43.4% of that of North Korea, the winning possibility will be lower and the military operations will be in critically difficult situation. [Military Reform Plan 2020] rums at the reduction of troops and units of the ground forces under the policy of 'select few'. However, the problem is that the financial support to achieve this goal is not secured. Therefore, the promotion of [Military Reform Plan 2020] may cause the weakening of military defence power in 2020. Some advanced countries such as Japan, UK, Germany, and France have promoted the policy of 'select few'. However, what is to be noted is that the national security situation of those countries is much different from that of Korea. With the collapse of the Soviet Unions and European communist countries, the military threat of those European advanced countries has almost disappeared. In addition, the threats those advanced countries are facing are not wars in national level, but terrorism in international level. To cope with the threats like terrorism, large scaled army trops would not be necessary. So those advanced European countries can promote the policy of 'select few'. In line with this, those European countries put their focuses on the development of military sections that deal with non-military operations and protection from unspecified enemies. That is, those countries are promoting the policy of 'select few', because they found that the policy is suitable for their national security environment. Moreover, since they are pursuing common interest under the European Union(EU) and they can form an allied force under NATO, it is natural that they are pursing the 'select few' policy. At present, NATO maintains the larger number of troops(2,446,000) than Russia(l,027,000) to prepare for the potential threat of Russia. The situation of japan is also much different from that of Korea. As a country composed of islands, its prime military focus is put on the maritime defense. Accordingly, the development of ground force is given secondary focus. The japanese government promotes the policy to develop technology-concentrated small size navy and air-forces, instead of maintaining large-scaled ground force. In addition, because of the 'Peace Constitution' that was enacted just after the end of World War II, japan cannot maintain troops more than 240,000. With the limited number of troops (240,000), japan has no choice but to promote the policy of 'select few'. However, the situation of Korea is much different from the situations of those countries. The Republic of Korea is facing the threat of the North Korean Army that aims at keeping a large-scale military force. In addition, the countries surrounding Korea are also super powers containing strong military forces. Therefore, to cope with the actual threat of present and unspecified threat of future, the importance of maintaining a carefully calculated large-scale military force cannot be denied. Furthermore, when considering the fact that Korea is in a peninsular, the Republic of Korea must take it into consideration the tradition of continental countries' to maintain large-scale military powers. Since the Korean War, the ROK army has developed the technology-force combined military system, maintaining proper number of troops and units and pursuing 'select few' policy at the same time. This has been promoted with the consideration of military situation in the Koran peninsular and the cooperation of ROK-US combined forces. This kind of unique military system that cannot be found in other countries can be said to be an insightful one for the preparation for the actual threat of North Korea and the conflicts between continental countries and maritime countries. In addition, this kind of technology-force combined military system has enabled us to keep peace in Korea. Therefore, it would be desirable to maintain this technology-force combined military system until the reunification of the Korean peninsular. Furthermore, it is to be pointed out that blindly following the 'select few' policy of advanced countries is not a good option, because it is ignoring the military strategic situation of the Korean peninsular. If the Republic of Korea pursues the reduction of troops and units radically without consideration of the threat of North Korea and surrounding countries, it could be a significant strategic mistake. In addition, the ROK army should keep an eye on the fact the European advanced countries and Japan that are not facing direct military threats are spending more defense expenditures than Korea. If the ROK army reduces military power without proper alternatives, it would exert a negative effect on the stable economic development of Korea and peaceful reunification of the Korean peninsular. Therefore, the desirable option would be to focus on the development of quality of forces, maintaining proper size and number of troops and units under the technology-force combined military system. The tableau above shows that the advanced countries like the UK, Germany, Italy, and Austria spend more defense expenditure per person than the Republic of Korea, although they do not face actual military threats, and that they keep achieving better economic progress than the countries that spend less defense expenditure. Therefore, it would be necessary to adopt the merits of the defense systems of those advanced countries. As we have examined, it would be desirable to maintain the current size and number of troops and units, to promote 'select few' policy with increased defense expenditure, and to strengthen the technology-force combined military system. On the basis of firm national security, the Republic of Korea can develop efficient policies for reunification and prosperity, and jump into the status of advanced countries. Therefore, the plans to reduce troops and units in [Military Reform Plan 2020] should be reexamined. If it is difficult for the ROK army to maintain its size of 655,000 troops because of low birth rate, the plans to establish the prompt mobilization force or to adopt drafting system should be considered for the maintenance of proper number of troops and units. From now on, the Republic of Korean government should develop plans to keep peace as well as to prepare unexpected changes in the Korean peninsular. For the achievement of these missions, some options can be considered. The first one is to maintain the same size of military troops and units as North Korea. The second one is to maintain the same level of military power as North Korea in terms of military force index. The third one is to maintain the same level of military power as North Korea, with the combination of the prompt mobilization force and the troops in active service under the system of technology-force combined military system. At present, it would be not possible for the ROK army to maintain such a large-size military force as North Korea (1,190,000 troops and 86 units). So it would be rational to maintain almost the same level of military force as North Korea with the combination of the troops on the active list and the prompt mobilization forces. In other words, with the combination of the troops in active service (60%) and the prompt mobilization force (40%), the ROK army should develop the strategies to harmonize technology and forces. The Korean government should also be prepared for the strategic flexibility of USFK, the possibility of American policy change about the location of foreign army, radical unexpected changes in North Korea, the emergence of potential threat, surrounding countries' demand for Korean force for the maintenance of regional stability, and demand for international cooperation against terrorism. For this, it is necessary to develop new approaches toward the proper number and size of troops and units. For instance, to prepare for radical unexpected political or military changes in North Korea, the Republic of Korea should have plans to protect a large number of refugees, to control arms and people, to maintain social security, and to keep orders in North Korea. From the experiences of other countries, it is estimated that 115,000 to 230,000 troops, plus ten thousands of police are required to stabilize the North Korean society, in the case radical unexpected military or political change happens in North Korea. In addition, if the Republic of Korea should perform the release of hostages, control of mass destruction weapons, and suppress the internal wars in North Korea, it should send 460,000 troops to North Korea. Moreover, if the Republic of Korea wants to stop the attack of North Korea and flow of refugees in DMZ area, at least 600,000 troops would be required. In sum, even if the ROK army maintains 600,000 troops, it may need additional 460,000 troops to prepare for unexpected radical changes in North Korea. For this, it is necessary to establish the prompt mobilization force whose size and number are almost the same as the troops in active service. In case the ROK army keeps 650,000 troops, the proper number of the prompt mobilization force would be 460,000 to 500,000.

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