• The Journal of Korean Academy of Prosthodontics
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• v.38 no.4
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• pp.526-543
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• 2000

Finite element analyses were performed to study effects on stress distribution generated in jaw bone for various shapes of dental implants: plateau type, plateau with small radius of curvature, triangular thread screw type in accordance with ISO regulations and square thread screw filleted with small radius partially. It was found that square thread screw filleted with small radius was more effective on stress distribution than other dental implants used in analyses. Additional analyses were performed on the implant with square thread screw filleted with small radius for very-ing design parameters, such as the width of thread end, the height of the thread of the implant and load direction, to determine the optimum dimensions of the implant. The highest stress concentration occurred at the region in jaw Pone adjacent to the first thread of the implant. The maximum effective stress induced by a 15 degree oblique load of 100 N was twice as high as the maximum effective stress caused by an equal amount of vertical load. Stress distribution was more effective in the case when the width of thread end and the height of thread were p/2 and 0.46p, respectively, where p is the pitch of thread. At last, using tensile force calculated from the possible insert torque without breading bone thread, finite element analysis was performed on the implant to calculate pre-stress when the primary fixation of the implant was operated in jaw bone. The maximum effective stress was 136.8 MPa which was proven to be safe.

• Applied Biological Chemistry
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• v.35 no.3
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• pp.179-185
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• 1992

Rhizobium meliloti populated in five Korean pasture soils were characterized by symbiotic effectiveness and intrinsic antibiotic resistance using whole-soil inoculum and 11 antibiotics, respectively. Most probable number (MPN) of naturalized rhizobia counted with alfalfa Vernal[Medicago sativa (L.)] as a host ranged $1.7{\times}10^2\;cells/g$. soil(Chunghyo, Kyeongiu)-$1.0{\times}10^5\;cells/g$. soil(Gampo, Kyeongiu) and ended to be positively associated with soil pH. On the whole, the effectiveness of population as compared to TAL mix inoculum (TAL 380+TAL 1372+TAL 1373) was very low. Nevertheless, there were two highly effective strains, YCK 539 and YCK 542, which were not inferior to TAL 1372, from Ogpo, Dalseong among the total of 30 of 6 isolates per each soil. As long as mean $N_2$ fixing ability of each soil isolate, the isolates from Hyeongog, Kyeonju were outstanding and the rest were in order of Ogpo, Dalseong>Chunghyo, Kyeongju>Hwaweon, Dalseong>Gampo, Kyeongiu. Isolates as a whole were resistant to erythromycin(67崙), nalidixic acid(77%), and streptomycin sulfate(8051), which had the concentration of $100\;{\mu}g/ml$, $160\;{\mu}g/ml$, and $10\;{\mu}g/ml$, respectively and divided into 14 patterns of resistance. Association between resistances in each soil was not clear. And there was no relationship of resistance pattern to effectiveness. The best effective strain YCKa 542 exclusively fell into No. X pattern having resistance to erythromycin, nalidixic acid, and neomycin sulfate.

• Proceedings of the Ginseng society Conference
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• 1980.09a
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• pp.87-113
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• 1980

This experiment was carried out to evaluate the effects of Korean ginseng extract on carcinogenesis induced by various chemical carcinogens. Red ginseng extract was used for this study and was administered orally to the experimental animals. Carcinogens that were injected in subscapsular region of ICR newborn mice within 24 hours after birth were 9,10-dimethyl-1,2-benzan-thracene (DMBA), urethane, N-2-fluorenylacetamide(AAF), aflatoxin $B_1$ and tobacco smoke condensate. N -methyl-N -nitroso-N'-nitroguani-dine(MNNG) was injected subcutaneously at the back of wistar rats. Experimental animals were autopsied in immediately after being sacrificed. All major organs were examined grossly and weighted. After fixation histopathological preparations were made for microscopical study. Following results were obtained. In DMBA group sacrificed at the 26th week after the treatment with DMBA, the incidence of lung adenoma was $77\%$ and the average number of the tumor was 17. However, in DMBA combined with red ginseng group, the incidence was $78\%$ and the average number of lung adenoma was 14.1. This indicates that ginseng extract had no effect on the incidence of lung adenoma but decreased the average number of lung adenoma by $17\%.$ In DMBA group sacrificed at the 48th week after the injection of DMBA, the lung adenoma incidence was $88\%.$ The average diameter of the largest lung adenoma was 3.5 cm, the incidence of diffuse pulmonary infiltration was $18\%$ and the average lung weight of male experimental mice was $528.2{\pm}469.1\;gm.$ On the other hand, in DMBA combined with red ginseng group sacrificed at the 48th week, the incidence of lung adenoma was $96\%.$ The average diameter of the largest adenoma was 2.7 cm, the incidence of diffuse pulmonary infiltration was $7\%$ and the average lung weight of male mice was $418.0{\pm}520\;gm.$ These observations show that ginseng extract did not have any inhibitory effect on the incidence of lung adenoma but decreased the average diameter of the largest lung adenoma by $23\%,$ the incidence of duffuse pulmonary infiltration by $63\%$ and the average lung weight of male experimental mice by $21\%.$ From these results we have found that the prolonged administration with ginseng extract showed no inhibitory effect on the incidence of adenoma but it had the inhibitory effect on the proliferation of lung adenomas induced by DMBA. In urethane group sacrificed at the 28th week after the injection of urethane, the incidence of lung adenoma was $94\%$ and the average number of lung adenoma was 8.6. In urethane combined with red ginseng group, the. incidence of lung adenoma was $73\%$ and the average number of adenoma was 6.0. These results indicate that there were $22\%$ decrease of the lung adenoma incidence and $31\%$ decrease of the average number of adenoma in urethane combined with red ginseng group. And in urethane group sacrificed at the 50th week, the incidence of lung adenoma was $98\%$ and the incidence of diffuse pulmonary infiltration was $14\%$. In urethane combined with ginseng group the incidence of lung adenoma was $85\%$ and the incidence of diffuse pulmonary infiltration was $12\%$. Therefore the ginseng administration resulted in $15\%$ decrease of the lung adenoma incidence and $14\%$ decrease of the diffuse pulmonary infiltration incidence. From these results we knew that the prolonged administration with ginseng extract inhibited the incidence and also the proliferation of the lung adenoma induced by urethane. Lung adenoma and hepatoma were induced in the experimental mice sacrificed at the 68th week but not in the experimental mice sacrificed at the 28th week after the injection of AAF. In AAF group sacrificed at the 68th week after the injection of AAF the incidence of lung adenoma was $18\%$ and the incidence of hepatoma was $27\%$. And in AAF combined with ginseng group the lung adenoma incidence was $12\%$ and the hepatoma incidence was $37\%$. So the ginseng seemed to decrease the lung adenoma incidence by AAF, but we were unable to conclude the significant inhibitory effect of the ginseng extract on the incidence of lung adenoma by AAF because the above incidence of lung adenoma were similar to that of control group which was $11\%$. And these experimental data revealed that ginseng extract didn't have any inhibitory effect on the incidence of hepatoma induced by AAF. In aflatoxin $B_1$ group sacrificed at the 56th week, the incidence of lung adenoma was $24\%$ and hepatoma was $11\%$. However in aflatoxin $B_1$ combined with ginseng group the incidence of lung adenoma was $17\%$ and hepatoma was $3\%$ These results indicate that there were $29\%$ decrease of the lung adenoma incidence and $75\%$ decrease of the hepatoma incidence in aflatoxin $B_1$ combined with ginseng group. In tobacco smoke condensate experimental group sacrificed at 67th week, no tumors were induced except just a few lung adenoma. The lung adenoma incidence both in tobacco smoke condensate group and in tobacco smoke condensate combined with ginseng group was $8\%$. And this incidence rate was similar to that of control group. These results indicate that the injection of 320 ug tobacco smoke condensate per ICR newborn mouse was unable to induce lung adenoma in our experiments. In MNNG group sacrificed at the 27th week the tumor incidence was $38.5\%$ and in MNNG combined with ginseng extract group was $37\%$. In MNNG group for investigation of the life span of tumor bearing rats the tumor incidence was $93\%$ and the average life span of tumor bearing rats was 318 days. And in MNNG combined with ginseng extract group the tumor incidence was $96\%$ and the average life span was 337 days. Tumor induced by MNNG was almost sarcoma. This indicates that there was no inhibitory effect of ginseng extract on the tumor incidence, but the extract prolonged the average life span of tumor bearing rats by approximately 19 days.

• Korean Journal of Organic Agriculture
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• v.16 no.4
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• pp.435-453
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• 2008

The crop rotation is very important in the organic agriculture and the soybean crop should be included in the rotation. Even though the inoculation of the root can be performed by the soil inoculation in the soybean crop, the effect of the soil inoculation should be proved in the organic soil. For the research of the effects in the formation of the nodule of soybeans, the growth and the quantity through the inoculation into the soil, the field experiment was conducted in 2006 at Ipjang Experimental Farm of Dankook University. The number of nodule in the testing varieties of the inoculated soil plot was $1.4{\sim}2$ times larger than those in the non-inoculated soil plot. The number of nodule was decreased in the non-inoculated soil plot after R2 stage, but it was increased in the inoculated before R4 stage and it was decreased after then. The periodical change of weight of the nodule was shown as same as the number of nodule. The dry weight of inoculated was increased than non-inoculated in Daewonkong, but it was decreased than non-inoculated in Shinpaldalkong2 and SS2-2. The amount of chlorophyll of the inoculated soil plot was more than the non-inoculated soil plot by 9% in Daewonkong, but the inoculated soil plot was less than the non-inoculated soil plot by 13%, 33% each in Shinpaldalkong2 and SS2-2. The number of pods, the number of grains and the weight of grains in the yield characteristics of the inoculated soil plot were more than in the non-inoculated soil plot in Daewonkong, but the number of pods, grains and the weight of grains in the yield result in the inoculated soil plot was less than in the non-inoculated soil plot in Shinpaldalkong2 and SS2-2. The mean yield(per 10a) of Daewonkong was increased 11% in the inoculated soil plot, but the mean yeil(per 10a) of Shinpaldalkong2 was decreased 4% and SS2-2 was also decreased 23%.

• Clinical and Experimental Pediatrics
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• v.51 no.8
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• pp.874-878
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• 2008

Purpose : This study was undertaken to develop an animal model of periventricular leukomalacia (PVL) induced by in utero clamping of pregnant rat aorta in fetal rats. Methods : A timed pregnanct Sprague-Dawley rat on embryonic day 21 just prior to delivery was sedated and anesthetized, and a Harvard ventilator for small animals was applied. Following laparotomy, the maternal aorta was clamped reversibly for 40 minutes using a surgical clip. The fetal rats were then delivered by Cesarean section, resuscitated if necessary, and reared by a surrogate mother rat until postnatal day 21 to obtain the brain specimen. After systemic perfusion and fixation, $10{\mu}m$ thick serial brain sections were obtained and stained for pathologic examination and assessment of ventriculomegaly. Ventriculomegaly was assessed by the measured ventricle to total brain volume ratio. Results : Eight out of eleven fetal rats (73%) survived in the ischemia group after induction of in utero ischemia by clamping maternal rat aorta, and all ten survived in the control group. Body and brain weights measured at postnatal day 21 were significantly lower in the ischemia group compared to the control group. In pathologic findings, significant ventriculomagaly ($3.67{\pm}1.21%$ vs. $0.23{\pm}0.06%$) was observed in the ischemia group compared to the control group; although cystic lesion was not observed, mild (n=6) and moderate (n=2) rerefaction of the brain tissue was observed. Conclusion : A fetal rat model of PVL induced by in utero clamping of pregnant rat aorta was developed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.147-153
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• 1982

Nitrate and nitrite, which readily produce N-nitrosamines by reaction with secondary amines, are widely distributed in natural products such as vegetables and cereals, and are also used as a color fixation in meat products or fish roes. This experiment was carried out to determine the contents of nitrate and nitrite in foods such as fermented sea foods and fresh vegetables purchased at markets in Korea. The contents of nitrate were $0.74\sim13.81\;ppm$ for fermented sea foods and $4.0\sim1,572.5\;ppm$for fresh vegetables. As for vegetables, the nitrate levels of edible herbs were relatively higher than those of greens, fruits and rootcrops. The nitrite contents in fermented demoisells(Chromis notatus), fermented shrimp, fermented small squid, fermented anchovy and salted Alaska pollack roe were very little, while those in fermented hairtail and fermented entrails were not detected. As for vegetables, nitrite levels found for cabbage and lettuce were relatively as high as 3.8 ppm and $2.5\sim2.9\;ppm$, respectively, but were not detected in Korean cabbage, green perilla leaf, pepper, garlic and burdock. Of vegetables, the nitrate values in the outer part of Korean cabbage, stems of water cress and leaves of green onion were higher than in the other parts. Little variety of the nitrate levels were found during 4 days storage. In the comparison of low temperature storage and room temperature storage, lettuce, pumpkin and spinach contained higher levels of nitrate at low temperature storage, while eggplant and green onion, at room temperature storage.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.1
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• pp.72-77
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• 1989

A study was conducted to obtain acid tolerant and superior Rhizobium meliloti strain for alfalfa on hilly acid soils. With host plant, eight isolates of R, meliloti selected in the vicinity of Milyang were evaluated for their ability to establish symbiotic effectiveness in acidified tube culture medium and vermiculite pot with different urea levels. Among isolates "YA03" was characterized for the ability to manifest to acid tolerance in three different soils of which pH were 5.0, 6.0, and 7.5. The results obtained were summarized as follows: 1. Of eight isolates "YA03" and "YA09" performed nodule in the tube medium of pH5.0, and in the symbiotic effectiveness YA03 was superior to others. 2. Alfalfa growth and $N_2-fixing$ activity by the inoculation of "YA03" isolate were better than others at the level of urea 1.25mM as well as nonurea. 3. Application of urea with inoculation of "YA03" islate to alfalfa was one of the effective factors for symbiotic effectiveness. 4. In infertile soil of pH5.0 inoculation of R. meliloti "YA03" to alfalfa caused the increase of shoot dry matter of 320% as compared to the control, and the total amount of yield was 131% as much yield in moderate fertile soil of pH7.5. Finally R. meliloti "YA03" isolate was selected as an acid tolerant strain.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.2
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• pp.81-87
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• 1979

In order to observe the lasting effect of NK-compound mineral fertilizer and organic compound fertilizer including Myweon organic liquid fertilizer, a pot experiment was conducted with rice (Oriza Sativa) variety: Nong Back. These fertilizers were applied as basal and the same amount of urea form of nitrogen was top dressed about a month after transplanting, July seventh, 1977. Results obtained are as follows; 1. The lasting effect of various fertilizers were laid in following decreasing order; Myweon liquid < Organic compound fertilizer (Myweon coop. made) > NK-compound fertilizer (Chosun coop. made) Single fertilizer. It was considered that organic matter served as microbial feed and lead a temporary fixation of available plant nutrients in the soil, and the reduced surface area of the compound fertilizers slowed down the availability of the fertilizers. 2. The fertilizer showing greater lasting effect produced more panicles per hill and less grains per panicle than the fertilizers showing less lasting effect, and brought low maturity, which resulted in low paddy yield the paddy producing efficiency of nitrogen absorbed by straw was also low in the former fertilizers. Such advanced effect of the former fertilizer was considered to be related with the variety of early maturity and unseasonable topdressing of fertilizer which made at the maximum tillering stage. 3. For the production of Japonica type paddy with heavy fertilization which may required to depress the early growth a little and promote the late growth, it might be necessary to develop slow releasing fertilizers such as single fertilizer formulated to a large grains or compound fertilizer containing organic matter. 4. If the nitrogen content of paddy, Nong Back, far excess 0.64 or 0.65% and reaches 0.68% or above, the yield of the variety seemed to be decreased remarkbly through the low maturity rate and thousand grain weight.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.323-330
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• 2013

This study was conducted to know the effect of major physical-chemical characteristics of soil to be in the area of indigenous and naturalized plant in the sand dune of the western coastal area of Korea. The study was performed on the sand dunes distributed across Taean-gun and Buan-gun and the study period was from April to October in 2010. Sixty nine of $5m{\times}5m$ study plots were installed and the distribution of plants were investigated. We measured the soil characteristics including soil pH, organic matter, total nitrogen, available $P_2O_5$, soil cation exchange capacity, exchangeable cation, EC and NaCl. As a result, soil texture was classified as sand, in case of average pH, NaCl, and EC of soil to be in the area of indigenous herbaceous plant were 7.77, 0.03% and $0.52ds.m^{-1}$, indigenous woody plant of the mean pH, NaCl and EC were 7.31, 0.01%, $0.23ds.m^{-1}$. In case of naturalized herbaceous plant of the mean soil pH, NaCl and EC were 7.12, 0.01%, $0.29ds.m^{-1}$, naturalized woody plant of the mean soil pH, NaCl and EC were 7.34, 0.01%, $0.20ds.m^{-1}$ respectively. On average, naturalize plants showed in low salinity concentration than indigenous plants.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.175-180
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• 2008

Traumatic injuries to the primary dentition are commonly encountered problems in dental practice. It is found that 30% of the children had injuries to the primary dentition and 22% to the permanent dentition. The greatest incidence of trauma to the primary dentition occurs at the ages of 2 and 3 as children start to learn motor coordination. Because teeth and alveolar bone are traumatized simultaneously, alveolar bone fractures are likely to occur when multiple teeth are involved in injuries. Dental splints are indicated for the management of maxillofacial fractures. They enable anatomic reduction of fractured segments and help immobilization and maintenance of the fragments after reduction. They also act as a stabilizer during rehabilitation. Various types of dental splints are available. In this case, routine resin-wire splint technique could not be applied because of the child's uncooperative behavior. Oral sedation was not indicated because N.P.O. had not been preceded. Therefore, we decided to use open-cap acrylic splint instead. Stabilization using open cap acrylic splint requires minimum chair time with reduced discomfort to both patient and dentist. It is an effective means of splint for uncooperative children and especially useful when other means of fixation have been failed. Because trauma on the primary dentition can affect the underlying permanent tooth germ, it is important to monitor eruption process of the permanent dentition.