• Title/Summary/Keyword: Wind-effect

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A Study on the Sailing Speed of Ancient Ships - especially on the average speed and the effect of the wind, the tide, and the man-power at the oar - (고대 선박의 항해속도 연구 - $\ll$고려도경$\gg$을 중심으로-)

  • Yoon, Il-Young
    • Journal of National Security and Military Science
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    • s.7
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    • pp.155-231
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    • 2009
  • Xu-Jing(徐競) an official of the Song(宋), a medieval Kingdom of China, wrote a book titled $\ll$Koryo Tu Jing(高麗圖經)$\gg$ which explains his travel to the Koryo as a member of diplomatic mission in 1123. $\ll$Koryo Tu Jing$\gg$ is the record of his personal experience in Koryo with many explanatory illustrations and especially contains 5 months' voyage record of his diplomatic fleet. His fleet set sail at a port located in the Ding Hai Xian(定海縣), Ming Zhou(明州) via a few islands of Koryo [Hyup Kye San(俠界山) , the Kun San Do(群山島) , the Ja Yon Do(紫燕島) , the Keup Su Mun(急水門) in Kang Hwa Gun(江華郡) and the Hap Gul(蛤窟) ] and finally arrived the Port Ye Song Hang(禮成港) . According to the Xu-Jing's record his fleet sailed the sea with the help of the favorable seaward winds and tides as the usual way of ancient sailing. The Xu- Jing's Fleet sailed the sea between the Mei Cen(梅岑), Ming Zhou(明州) of China and the Hyup Kye San(俠界山) of Koryo from about 5:00 a.m., May 24th(of the lunar calendar) to about 5:00 p.m., June 2nd. At this section, the average speed of the seaward winds was 19.45km/h and the average speed of the fleet which sailed only by the power of the winds was 6.29km/h. This means that 32.3% of the favorable seaward winds' speed was equal to the speed of the ancient fleet which sailed only by the power of the favorable seaward winds. The fleet sailed the sea between the Ja Yon Do(紫燕島) and the Keup Su Mun(急水門) from about 9:00 a.m., June 10th to about 1:00 p.m., the same day. At this section the fleet sailed by the power of tides in addition to the favorable seaward winds without oaring. The average speed of the winds was not different from that of former section and the average speed of the tides was 1.937km/h. And at this section the average speed of the fleet increased by 0.41km/h than that of the former section. This means that 21.1% of the speed of the tides was equal to the increased speed of the ancient fleet by virtue of the tides. The fleet sailed the sea between Keup Su Mun(急水門) and the Hap Gul(蛤窟) from about 1:00 p.m., June 10th to about 3:00 p.m., the same day. At this section, there were no seaward winds and the fleet sailed only by the powers of tides and oaring. And at this section, the tide increased the average speed of the fleet by 0.3114km/h and the fleet could sail at the speed of 4.3km/h. So we can conclude that the average speed of ancient fleet without any influences of the seaward winds and tides was 3.98 km/h. We can make use of the various sailing speeds of ancient fleets when judging their maritime activities. If we make use of the various sailing speeds of the ancient fleets as calculated in this article, we will be able to get various important informations about the certain ancient fleet's maritime maneuver. For example, we can infer the sailing routs of a certain fleet and the time when the fleet passed a certain spot by making use of the various sailing speeds of the ancient fleet. In this article I did not take account of the shapes of ships that consist of the ancient fleets and the sizes of the various ships and fleets. It was because that such factors would not change the foresaid conclusions seriously.

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Beneficial Effect of Heat Fans on Quality and Yield of Korean Melon Cultivated in Greenhouses at Winter Season (히터팬 처리가 저온기 하우스 참외의 품질 및 수량에 미치는 긍정적 영향)

  • Shin, Yong Seub;Lee, Ji Eun;Oh, Su Whan;Cheung, Joung Do;Sohn, Hyoung Rac;Do, Han Woo;Kim, Mi Kyung
    • Journal of Bio-Environment Control
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    • v.26 no.3
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    • pp.188-193
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    • 2017
  • The purpose of this study was to investigate the changes of environmental conditions and the quality and yield of melon fruit by heat fan operation in greenhouses at winter season. The average daily temperature inside the tunnels during January 1 to 31, 2017 was $0.9^{\circ}C$ higher than that of the control $17.8^{\circ}C$. The air flow rate of heater fan treatment was 4.8 times higher than the control (untreated $0.05m{\cdot}s^{-1}$) at 20cm above the ground where the korean melon grew. The temperature of the heater pan was $5.6^{\circ}C$ higher than that of the untreated at $35.3^{\circ}C$ and the relative humidity was 8.1% lower than that of the untreated at 39.1%. The flowering rate of the heater fan treatment was 96%, 5% higher than the control. The number of first harvest days of heater fan treatment was shortened by 4 days than that of untreated treatment. Fruit quality and marketable fruit yield increased by 3.4% and 38% compared to untreated respectively, the heater fan treatment increased the temperature inside the greenhouse and air flow rete, which were beneficial for growing the korean melon in greenhouses at winter season.

Heojun's Outlook on Nature (허준(許浚)의 자연관(自然觀) - 『동의보감(東醫寶鑑)』을 중심으로 -)

  • Park, Seong-Kue;Kim, Sue Joong;Kim, Nam Il
    • The Journal of Korean Medical History
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    • v.18 no.2
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    • pp.197-227
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    • 2005
  • Heojun was the top scientist on Medicine in the 16th and 17th centuries and wrote the Dongeubogam describing the top-level medical theory and technology. So far, his outlook on nature has been disregarded even though his medicine is still effective. Through this study, I would like to know if his outlook on nature as well as his medicine is still effective. The conclusions are as follows: 1. According to his output, the origin of the universe started from the spinning of One Gi(一氣) which is quite different from Hawking's theory. Hawking assumed that the origin of the universe started from the Big-bang and will end to the Big-crunch. However, the current report on the origin of a star is quite similar to Heojun's theory and we acknowledge that his view on the origin of the universe is still effective. 2. According to his output, the universe repeats expanding and contracting forever while Hawking assumed it will come to the end, the Big-crunch, based on the expanding universe theory. Some scientists assists that Hawking's assumption should have some contradictions. Now, we acknowledge that Heojun's universal cycling theory which corresponds with modern physical theories is still effective, which would lead to a new environmental movement. 3. His view on the structure of the universe is quite different from the output of the current science, which results from his thought that the nature should be reviewed from the point of human's view. His view on the structure will be able to be updated based on the output of the current science. 4. The universe analogy started from the East Asian area as well as the Greek and Roman area in the ancient. The idea has disappeared since the scientific revolution era in the West while the idea has been deepened and abundant in the East and has become one of the major philosophical bases. Heojun emphasized its importance from the beginning of his book. 5. The nation analogy has been popular all times and places. According to his output, governing a country is like controlling one's body. 6. According to Needham's output, the universe analogy and the nation analogy were based on the ancient developed alchemy. And Harper assumed that Taiosm was based on the macrobiotic hygiene which was developed by the ancient developed alchemists. We acknowledge that xian(仙) cult, macrobiotic hygiene, medicine, alchemy and the ancient philosophy started from our ancients. Heojun's output restored our ancient tradition by combining the macrobiotic hygiene and philosophy with medicine. 7. Roughly predicting yearly weather would be unacceptable by the current scientist but Heojun's yearly weather forecast is still used in the clinic and seems effective to prepare from any epidemic disease. 8. 'Day and Night' and Four seasons are the most important factors to the macrobiotic hygiene according to the Dongeubogam. The new environmental movements should be based on the most important factors, otherwise the human beings as well as the environment would fail to survive. 9. Wind, Coldness, Heat, Humidity, Dryness and Fire represents weather. The six weather factors represent one of six phases of a year which is decided by the areal factors. Heojun preferred the six factors generated in the body itself to them from the outside. He thought a human being was a universe and the six factors generated in the body responded to the factors of the outside. 10. According to his output, Heat and Humidity are the most important factors which make a human being ill. 11. Life span, disease, food, and dwelling are dependent upon the geographical feature, according to Heojun's output. In addition, one's appearance and his five viscera and the six entrails depend on the food as well as the geographical feature. 12. Heath is related with the environment and they effects upon each other. If one is weak, he will be deeply effected by the nature. On the other hand, if one is strong, he will effect on the nature. That's why people live together. 13. According to Heojun's work, the society is an important factor comprising the environment. During a peaceful era, the society becomes stable and human beings are stable as well while they will be on fire during a chaotic era. 14. Medicine deals with human beings who live in the nature, so any medical book cannot be excellent unless it has any description on the nature. Heojun's outlook on the nature turned out to be logical and suitable even from the point of the current view and it is still effective as if his clinical knowledge and technology are still effective. Something unsuitable may be substituted with the output of the current science.

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Pedological Characteristics of Asian Dust in Korea (한국에 강하한 황사의 토양학적 특성)

  • Zhang, Yong-Seon;Kim, Yoo-Hak;Sonn, Yeon-Kyu;Lee, Gye-Jun;Kim, Myung-Sook;Kim, Sun-Kwan;Weon, Hang-Yeon;Joa, Jae-Ho;Eom, Ki-Cheol;Kim, Sang-Hyo;Kwak, Han-Kang;Kim, Han-Myeong
    • Korean Journal of Soil Science and Fertilizer
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    • v.38 no.6
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    • pp.301-306
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    • 2005
  • Asian dust was collected in Korea and soils in the arid area of northern China were analysed for its physical and chemical properties, and mineral compositions for in order to interpret the origin of Aeolian soils and estimate the effect of dust wind on the soil environment in Korea. Asian dust was collected at Suwon in Korea from 2002 to 2004. Soil samples were collected from the desert and Loess plateaus around Gobi desert in China. As a result of analysis of desert soil distributed on northern region and Loess soils in China, it was observed that soil pH was about 9, organic matter 11 to $23g\;kg^{-1}$, and CEC 7.1 to $18.4cmolc\;kg^{-1}$, showing a high spatial variation among different sampling locations. About 62 to 80% of particles were composed of quartz and feldspars, 2 to 14% calcite ($CaCO_3$) and dolomite [$Ca{\cdot}Mg(CO_3)_2$], and trace other clay minerals. All the dust particles in Korea were below 50 m in diameter, and the mineral compositions were quartz, mica, feldspar and some clay minerals. Major components of clay mineral of Asian dust was mainly illite as compared to the kaolin of soils in Korea. The base saturation of exchangeable Ca, Mg, K and Na in the Asian dust was above 250% due to the high content calcite. Most of upland soil in Suwon was thin and sharp type, but Asian dust in Korea was the spherical shape. Asian dusts in Suwon, Korea, did not show a definite mineralogical variation of the dust during the collection period. Difference between the Asian dust collected in Korea and the soils in arid area of China was observed in the physical and chemical properties, especially for particle size distribution, cations such as Ca, Mg, K and Na. However, some similarities were found on the mineral compositions and chemical properties between Asian dust collected in Korea and the loess of China.

A Study on the Effects of Temperature Rise of Irrigation Water Passed Through the Warm Water Pool. (온수지에 의한 관개용수의 수온상승 효과에 관한 연구)

  • 연규석;최예환
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.19 no.1
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    • pp.4323-4337
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    • 1977
  • The study was to estimate the effect of the rise of water temperature in the warm water pool and to make contribution to the establishment of reducing to a damage of cool water as well as to the planning for warm water pool. This observation was performed in Wudu warm water pool located at Wudu-Dong of Chuncheon for two years from 1975 to 1976. The results were showed as follows; 1. The daily variation of water temperature was the least for inset (No.1; 0.6$^{\circ}C$) the second for middle overflow (No2: 3$^{\circ}C$, No.3; 2.3$^{\circ}C$) and another for outflet (No.4; 3.6$^{\circ}C$, No.5; 3.8$^{\circ}C$) And the highest reaching time of water temperature in each block was later about 1 hour than the time at which air temperature happend in the daytime. So, the variation of water temperature was sensitive to the variation of air temperature 2. The monthly variation of water temperature at each measuring point was plotted to be increased with increase in air temperature till August (Mean monthly rising degree; No.1; 1.15$^{\circ}C$, No.2; 1.7$^{\circ}C$, No.3; 1.73$^{\circ}C$, No.4; 2.08$^{\circ}C$, No.5; 2.0$^{\circ}C$), and expressed gradually descended influence upon water temperature after August. 3. The mean temperature of inflow folwed in warm Water pool was 7.5∼12.5$^{\circ}C$, and outflow temperature was described as 13.4∼22.5$^{\circ}C$ to be climbed. And So, the rising interval of water temperature was shown as 6.7∼10.4$^{\circ}C$. 4. The correlation between the rising of water temperature and the weather condition was found out highly significant. As the result, their correlation coefficents of water temperature depending on mean air temperature, ground temperature, wind velocity and relative humidity were to be 0.93, 0.90, - 0.83 and 0.71 respectively. But there was no confrimation of the correlation on the clouds, sunlight time, volume of evaporation, and heat capacity of horizontal place. 5. The water temperature of balance during the period of rice growing in Chuncheon district was shown as table 10, and the mean of whole period was calculated as about 23.7$^{\circ}C$. 6. The observed value of the outflow temperature passed through the warm water pool was higher than that of computed, the mean difference between two value was marked as 1.15$^{\circ}C$ for blockl, 1.18$^{\circ}C$ for block2, and 0.47$^{\circ}C$ for block3, respectivly. Therefore, the ratio on the rising degree between the observed and computed were shown as 53%, 44%, and 18%, mean 38% through each block warm water pool (referring item $\circled9$ of table 11,12, and 13). Accordingly, formula (4) in order to fit for each block warm water pool was transfromed as follow; {{{{ { theta }_{w } - { theta }_{ 0} =[1-exp LEFT { { 1-(1+2 varphi )} over {cp } CDOT { A} over { q} RIGHT } ] TIMES ( { theta }_{w } - { theta }_{ 0}) TIMES C }}}} Here, correction coefficinent was computed 1.38, and being substituted 1.38 for C in preceding formula, the expected water temperature will be calculated to be able to irrigate the rice paddy. As the result, we can apply the coefficient in order to plan and to construct a new warm water pool.

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A Study on the Plant Planning in Landscape Space Considering the Characteristics of the Gender Determination of Pine Tree (소나무 성 결정 요인의 특성을 고려한 조경공간 식재계획)

  • Lee, Chang-Hun
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.38 no.1
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    • pp.45-52
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    • 2020
  • This study analyzed the components contained in the pine needles of first and second-year-olds to analyze the factors that the in vivo content of inorganic elements affects the sex determination of pine trees. In response, the plan for pine tree plant and maintenance was intended to be presented in consideration of the reproductive environment and physiological characteristics. The results are as follows. First, last year, when there were many encyclopedias, the analyzed N(%) content was found to be high. The nitrogen content of the previous year's soil was found to affect the production of the spheres the following year. This is believed to be possible to reduce the rate of Pine pollen produced in the new plant in the following year through a dispute over quality consumption in the spring of the previous year. Second, the weapons elements involved in the Pine cones and the generation of the Pine pollen in the new plant appeared to be P(%), K(%), Ca(%), and Fe(%). However, the nutrients from the previous year's leaves of Ca(%) and Fe(%) were found to have a low influence on the sex determination of first-year pine trees. Because Ca(%) and Fe(%) are not able to move nutrients accumulated in aging organs due to the nature of the components, feeding nutrients in the fall when the growth of the previous year's branches is reduced is expected to affect oral generation. Third, pine trees are extremely positive and Pine pollen is related to the time of the northeast wind. Therefore, it is believed that it would be good to be located in the northern direction, where the sunlight is good, in an outdoor space. In addition, it is important to use vaginal consumer products in spring and carry out a quarrel involving Mg and Fe during fall to reduce the effect of the Pine pollen, which is an outdoor plant. This is an important part of maintaining and managing pine trees in outdoor spaces as well as the sex determination of pine trees. This study suggested that plant planning, which derives the correlation between pine inorganic element content on sexual determination and takes into account the physiological characteristics of pine trees, is an important issue in the creation of outdoor space. Follow-up research on other factors affecting pine tree sex determination is expected.

Stimulation of Flowering in Chamaecyparis obtusa Grafts by Gibberellin Treatments (Gibberellin 처리(處理)에 의(依)한 편백나무의 개화촉진(開花促進))

  • Kim, Won Woo;Kim, Zin Suh
    • Journal of Korean Society of Forest Science
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    • v.87 no.4
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    • pp.549-556
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    • 1998
  • To develop the effective methods of flowering stimulation, Hinoki cypress (Chamaecyparis obtusa Sieh. et Zuec.) grafts growing in a seed orchard and in a clone bank in Southern Breeding Station of Cheju were applied with gibberellin treatments, and predicted the seed production potential. In the seed orchard, $GA_{4/7}$ 1.5cc was injected into the stem of drafts and sprayed whale tree crown with $GA_3$ 300ppm and $GA_{4/7}$ 300ppm. Un the other hand, in the clonal archives, drafts were given intrusion of $GA_{4/7}$ 1.5cc into the excised and open inner part of bark wind $GA_3$ 20mg and sprayed with $GA_3$ 300ppm. Additionally, grafts growing in the seed orchard were treated with gibberellins at 3 different periods of time and 3 different treatments during the growing season. The results obtained here are summarized as follows : 1. All of the applications of Gilbberellin promoted female flower formation. Among these, the treatment of intrusion of $GA_{4/7}$ 1.5cc into the excised and open inner part of bark was racist effective, followed by the spraying of $GA_3$ 300ppm. Similarly, the applications of gibberellin promoted male flower formation. 2. Regarding the time of applications, treatment on August 15 was more effective than those of August 31 and September 11 in the stimulation of female flowers. On the contrary, there was no significant difference in the number of male flowers among 3 different time treatments. 3. It was supposed that the application of the intrusion of $GA_{4/7}$ 1.5cc into the excised and open inner part of bark on August 15 showing the best effect in female flower formation can produce 22.12kg seeds per ha. 4. Considerable significant difference existed among clones for both female and male flower formations. 5. Flower formation, especially female flower formation, seemed to be partially associated with the genetic potential of individual trees.

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The essay of Bijeung by chinese doctors in 20th century - Study of - (20세기(世紀) 중의사(中醫師)들의 비증(痺證)에 대(對)한 논술(論述) 연구(硏究) - 《비증전집(痺證專輯)》 에 대(對)한 연구(硏究) I -)

  • Kim, Myung Wook;Oh, Min Suk
    • Journal of Haehwa Medicine
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    • v.9 no.1
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    • pp.547-594
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    • 2000
  • I. Introduction The essence of Oriental medicine consists of ancient books, experienced doctors and succeeded skills of common society. Many famous doctors studied medical science by their fathers or teachers. So the history of medical science is long. $\ll$DangDaeMyeongIImJeungJeongHwa(當代名醫臨證精華)$\gg$ written by SaWoogWang(史宇廣) and DanSeoGeon(單書健) has many medical experience of famous doctors. So it has important historical value. Bi(痺) means blocking. BiJeung is one kind of symptoms making muscles, bones and jonts feel pain, numbness or edema. For example it can be gout or SLE etc. So I studied ${\ll}BiJeungJuJip{\gg}$. II. Final Decision Following decisions of Chinese doctors of 20th century are as follows ; 1. JuYangChun(朱良春) emphasized on IkSinJangDok(益腎壯督) to treat BiJeong. And he devided WanBi(頑痺) as PungHanSeup(風寒濕), DamEo(痰瘀), YeolDok(熱毒), SinHeo(腎虛). He used insects for medicine. 2. ChoSuDoek(焦樹德) introduced past prescription. He used ChiBiTang(治痺湯) to treat HaengBi(行痺), TongBi(痛痺), ChakBi(着痺). He insisted that Han(寒; coldness) and Seup(濕; dampness) be Eum(陰) and Pung(風; wind) can change his character to be Eum. After all BiJeung is usually EumJeung. So he used GaeJi(桂枝) and BuJa(附子). By the way he used ChungYeolSanBiTang(淸熱散痺湯) for YeolBi, BoSinGeoHanChiWangTang SaBok(王士福) emphasized on the importance of medicine. He introduced many treatments like CheongYeol(情熱) for YeolBi and YiO(二烏) for HanBi. And he divided BiJeung period for three steps. At 1st step, we must use GeoSa(祛邪), at 2nd step, we must use BuJeong(扶正) and at 3rd step, we must use BoHyeol(補血), he insisted. And he introduced many herbs to treat BiJeung. 4. JeongGwangJeok(丁光迪) said that GaeJi(桂枝), MaHwang(麻黃), OYak(烏蘖) and BuJa(附子) are very important for TongRak(通絡). And pain usually results from Han(寒), so he liked to use hot-character herbs. 5. MaGi(馬志) insisted that BiJeung usually result from ChilJeong(七情). And he liked to use insects for treatment of BiJeung. 6. WeolSeokMu(越錫武) introduced 8 kinds of treatments and divided BiJeung period. Also he divided BeJeung for PungBi(風痺), HanBi(寒痺) and SeupBi(濕痺). 7. SeoGeaHam(徐季含) observed many patients and concluded that 86.7% of BiJeung is HeuJeung(虛症). 8. YuJiMyeong(劉志明) said that YeolBi is important and CheongYeol is also important. So he emphasized on DangGyuiJeomTongTang(當歸拈痛湯) and SeonBiTang(宣痺湯). 9. WangLiChu(汪履秋) studied cause of WanBi. Internal cause is GiHyeolHeo(氣血虛) and GanSinHeo(肝腎虛) and external cause is SaGi(邪氣) he insisted. 10. WangSaSang(王士相) said that YeolBi can be SeupYeolBi or EumHeuYeolBi(陰虛熱痺) and HanSeupBi(寒濕痺) is rare. He use WooBangJaSan(牛蒡子散) and BangPungHwan(防風丸) for SeupYeolBi, DangGyuiSaYeokTang(當歸四逆湯) for HanSeupBi. 11. JinTaekGang(陳澤江) treated YeolBi with BaekHoGaGyeJiTang(自虎加桂枝湯) and SaMyoSan(四妙散). If they don't have effect, he tried to cure BiJeung step by step. And he used e term of GeunBi(筋痺) and BangGiMogwaEIInTang(防己木瓜薏苡仁湯) was good for GeunBi. 12. MaSeoJeong(麻瑞亭) said that PungSeupYeokJeul(風濕歷節) is BiJeung and it is related to GanBinSin(肝脾腎; liver, Spleen, Kindey). And he emphasized on balance WiGi(衛氣) and YoungHeul(營血). 13. SaJeJu(史濟桂) said that GeunGolBi(筋骨痺) is similar to arthritis and sometimes called ChakBi. And SinBi(腎痺) is terminal stage of ChakBi, he said. He also used insects for treatment. 14. JeongJeNam(丁濟南) tried to cure SLE and used GyeJi, CheonCho(川椒), SinGeunCho(伸筋草), SunRyeongBi(仙靈脾), HyconSam(玄蔘) and GamCho(甘草). 15. JinGYungHwa(陳景和) emphasized on diagnosis of tongue. If the color of tongue is blue, it usually has EoHyeol(瘀血), for example. And he also used insects. 16. JuSongI(朱松毅) tried to devide YeolBi with OnByeong(溫病), Wi(衛), Gi(氣) and Hyeol(血). 17. RuDaBong(蔞多峰) said that JyeongHeo(正虛), OiSa(外邪) and EoHyeol are closely related. And he explained BiJeung by deviding the body into the part, for example head, neck, shoulder, waist, upper limb and lower limb. 18. YuMuBo(劉茂甫) defined PungHanSyubBi as chronic stage and YeolBi as acute stage.

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Effect of moisture content on terminal velocities of domestic wheat and foreign materials (함수율에 따른 우리밀과 이물의 종말속도에 미치는 영향)

  • Choi, Eun-Jung;Kim, Hoon;Kim, Sang-Suk;Kim, Oui-Woung
    • Food Science and Preservation
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    • v.23 no.5
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    • pp.746-752
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    • 2016
  • This research was carried out to identify aerodynamic property as a function of moisture content for designing equipment such as for post-harvest management. Terminal velocity of two wheat varieties {Backjjung (B) and Jogyeong (J)} with selected sound, damaged kernel and foreign materials (Wheat stick, Wheat husks) were measured with a designed vertical wind column at different moisture contents from about 9 to 30% wet basis. The results showed that terminal velocity of wheat and foreign materials except of Jogyeong's husks (p<0.05) had a significant difference at p<0.001. With increasing moisture content, the aerodynamic property values of the kernels and foreign materials of the two wheat varieties increased linearly. In detail, terminal velocity of sound and damaged kernel increased from 5.46 to 7.13 m/sec (B) and 7.48 to 8.60 m/sec (J), damaged kernel from 5.91 to 7.00 m/sec (B) and 6.48 to 7.75 m/sec (J). For foreign materials the terminal velocity of wheat stick increased from 2.92 to 4.07 m/sec (B) and 3.74 to 5.22 m/sec (J) whereas that of husks from 1.07 to 1.85 m/sec (B) and 2.02 to 2.33 m/sec (J) each. For air separation of wheat and foreign materials, the air flow should be less than 5.22 m/sec due to the range (1.07~5.22 m/sec) of foreign materials in wheat.

CCD Photometric Observations and Light Curve Synthesis of the Near-Contact Binary XZ Canis Minoris (근접촉쌍성 XZ CMi의 CCD 측광관측과 광도곡선 분석)

  • Kim, Chun-Hwey;Park, Jang-Ho;Lee, Jae-Woo;Jeong, Jang-Hae;Oh, Jun-Young
    • Journal of Astronomy and Space Sciences
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    • v.26 no.2
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    • pp.141-156
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    • 2009
  • Through the photometric observations of the near-contact binary, XZ CMi, new BV light curves were secured and seven times of minimum light were determined. An intensive period study with all published timings, including ours, confirms that the period of XZ CMi has varied in a cyclic period variation superposed on a secular period decrease over last 70 years. Assuming the cyclic change of period to occur by a light-time effect due to a third-body, the light-time orbit with a semi-amplitude of 0.0056d, a period of 29y and an eccentricity of 0.71 was calculated. The observed secular period decrease of $-5.26{\times}10^{-11}d/P$ was interpreted as a result of simultaneous occurrence of both a period decrease of $-8.20{\times}10^{-11}d/P$ by angular momentum loss (AML) due to a magnetic braking stellar wind and a period increase of $2.94{\times}10^{-11}d/P$ by a mass transfer from the less massive secondary to the primary components in the system. In this line the decreasing rate of period due to AML is about 3 times larger than the increasing one by a mass transfer in their absolute values. The latter implies a mass transfer of $\dot{M}_s=3.21{\times}10^{-8}M_{\odot}y^{-1}$ from the less massive secondary to the primary. The BV light curves with the latest Wilson-Devinney binary code were analyzed for two separate models of 8200K and 7000K as the photospheric temperature of the primary component. Both models confirm that XZ CMi is truly a near-contact binary with a less massive secondary completely filling Roche lobe and a primary inside the inner Roche lobe and there is a third-light corresponding to about 15-17% of the total system light. However, the third-light source can not be the same as the third-body suggested from the period study. At the present, however, we can not determine which one between two models is better fitted to the observations because of a negligible difference of $\sum(O-C)^2$ between them. The diversity of mass ratios, with which previous investigators were in disagreement, still remains to be one of unsolved problems in XZ CMi system. Spectroscopic observations for a radial velocity curve and high-resolution spectra as well as a high-precision photometry are needed to resolve some of remaining problems.