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각막내피세포의 증식 및 손상의 회복에 대한 ROCK 억제제 Y-27632의 효과
김경환,정진권,류진숙,고아영,김미금,위원량,Kyeong Hwan Kim,Jin Kwon Chung,Jin Suk Ryu,MS,Ah Young Koh,BS,Mee Kum Kim,Won Ryang Wee 대한안과학회 2013 대한안과학회지 Vol.54 No.3
Purpose: To investigate the effect of ROCK inhibitor Y27632 on the human corneal endothelial cell proliferation in vitro and in vivo. Methods: Using corneal endothelial cells isolated and cultured from human donor cornea, we compared the effect of Y27632 (10 μM ) on the proliferation in vitro by flow cytometry analysis. For the evaluation of the effect of Y27632 (10 mM) in vivo, corneal thickness and wound area were analyzed for the corneal endothelial wound rabbit model induced by transcorneal freezing. Results: Ki67 positive cells were increased in the Y27632 group (9.1 ± 4.1 %) than the control group (8.0 ± 5.9 %), whereas annexin V positive cells in the Y27632 group (2.9 ± 1.0 %) were decreased compared to the control group (4.2 ± 2.2 %). However these were not statistically significant. Wound area after Y27632 application in animal model is concerned, the control group showed significant smaller area (45.6 ± 0.6 mm2) compared to the Y27632 group (49.3 ± 0.8 mm2; p = 0.029, Mann-Whitney U test), however, these were not significantly different from the baseline. Corneal thickness was not different between the two groups. Conclusions: Different from other reports for the effect of Y27632, no significant effect on the proliferation in vitro and wound healing in vivo, regarding human corneal endothelial cell, were found in this study.
김경환,이주은.Kyeong Hwan Kim. MD. Joo Eun Lee. MD. PhD 대한안과학회 2010 대한안과학회지 Vol.51 No.1
Purpose: To describe a transconjunctival sutureless technique for pars plana vitrectomy using conventional 20-gauge instruments. Methods: We performed transconjunctival sutureless pars plana vitrectomy (TSV) using conventional 20-gauge instruments in 36 eyes of 35 patients. We made 20-gauge transconjunctival beveled sclerotomies using microvitreoretinal (MVR) blades and used traditional 20-gauge instruments for the operations. Results: Eighty-three (81.4%) of 102 sclerotomies self-sealed without the need for sutures. The sutureless rate was even higher in the last one-third of the patients: 32 (94.1%) of 34 sclerotomy sites were sutureless. No serious complications were observed in our series, including postoperative hypotony, wound leakage, or endophthalmitis. Conclusions: The 20-gauge TSV technique is safe and can be utilized for almost all vitreoretinal diseases, without incurring additional cost for new instruments. J Korean Ophthalmol Soc 2010;51(1):22-28
김경환(Kyeong Hwan Kim),장직현(Jik Hyun Chang) 한국정보과학회 1994 정보과학회논문지 Vol.21 No.4
본 논문에서는 knapsack 문제에 대한 기존의 two-list 알고리즘에 분할 정복 방법과 정렬행렬을 도입한 병렬 알고리즘을 제안한다. 이 알고리즘은 CREW SM SIMD 모델에서 시간 복잡도 T=O(2 ⁿ/4), 하드웨어 복잡도 H=O(2 ⁿ/4)를 갖는다. 또 이 알고리즘에서는 T≤2 ⁿ/4)인 범위에서 T · H=O(2 ⁿ/2))이고 T≥2 ⁿ/4 인 범위에서 T · H³=O(2ⁿ)인 상반관계가 성립함을 보인다. In this paper, we propose a parallel algorithm based on a previously known two-list algorithm incorporating the divide-and-conquer method and sorted matrix for the knapsack problem. This algorithm achieves time complexity T=O(2 ⁿ /4) and hardware complexity H=O(2 ⁿ /4) on the CREW SM SIMD model. And we prove that there exists a time-hardware tradeoff T · H=O(2 ⁿ /2) when T≤2 ⁿ /4 and T · H³=O(2ⁿ) when T≥(2 ⁿ /4).
김경환(Kyeong-Hwan Kim),최종연(Jong-Yeun Choi) 한국기계가공학회 2012 한국기계가공학회지 Vol.11 No.3
Injection mold is a manufacturing process used to produce parts of complicated shape at a low cost. Many factors affect the quality of injection molded part during injection molding process. A study on the optimization of injection mold is progressed by using a simulation software like Moldflow. Filling, packing and cooling phases of injection molding processes are analyzed according to the mold design considering the shrinkage of molded part, the degree of filling rate and the wearing of a mold. Taguchi method is applied to analyze the significance of processing parameter and the dynamic characteristics according to the variation of processing parameters. From the results, the mold temperature and packing pressure influenced the shrinkage of injection molded part.
Delta 15 desaturase 유전자 억제에 의해 알파리놀렌산 함량이 낮은 들깨 육성
김경환(Kyung-Hwan Kim),이경렬(Kyeong-Ryeol Lee),김정봉(Jung-Bong Kim),이명희(Myoung Hee Lee),이은경(Eungyeong Lee),김년희(Nyunhee Kim),이홍석(Hongseok Lee),김송림(Song Lim Kim),백정호(JeongHo Baek),최인찬(Inchan Choi),지현소(Hyeonso 한국육종학회 2018 한국육종학회지 Vol.50 No.4
Perilla is an oilseed crop cultivated in Korea since ancient times. Due to the high α-linolenic acid content in perilla, perilla seed oil can easily become rancid. α-Linolenic acid is synthesized by two enzymes, endoplasmic reticulum-localized Δ15 desaturase (FAD3) and chloroplast-localized Δ15 desaturase (FAD7) in vivo. In order to lower the α-linolenic acid content of the seed oil without disturbing plant growth, we tried to suppress the expression of only the FAD3 gene using RNA interference, whilst maintaining the expression of the FAD7 gene. Seventeen transgenic plants with herbicide (Basta TM ) resistance were obtained by Agrobacterium-mediated transformation using hypocotyls of perilla plants. The transgenic plants were firstly confirmed by treatment with 0.3% (v/v) Basta TM herbicide, and the expression of FAD3 was measured by Northern blot analysis. The α-linolenic acid content was 10-20%, 30-40%, and 60% in two, seven, and three of the twelve T1 transgenic perilla plants which had enough seeds to be analyzed for fatty acid composition, respectively. Analysis of the fatty acid composition of T2 progeny seeds from T1 plants with the lowest α-linolenic acid content showed that the homozygous lines had 6-10% α-linolenic acid content and the heterozygous lines had 20-26% α-linolenic acid content. It is expected that the reduction in α-linolenic acid content in perilla seed oil will prevent rancidity and can be utilized for the production of high-value functional ingredients such as high γ-linolenic acid.
Cu-1.1wt% AI2O3 합금의 미세 조직과 기계적 성질
김경환(Kyeong Hwan Kim) 한국열처리공학회 2001 熱處理工學會誌 Vol.14 No.2
N/A Al₂O₃-copper alloy has been successfully made by gas atomization, mechanical alloying and hot pressing. In order to investigate microstructure and phase, it has been studied by using scanning electron microscope, transmission electron microscope and X-ray diffractometor. Mechanical properties have been examined using hardness tester and compressive tester according to annealing temperature. Although comparatively large Cu-Al powders are milled, the reaction between Cu-Al and Cu₂O occurs and very fine Al₂O₃particles in the matrix particles (5-10㎚) are obtained. Compressive strength of this alloy is more than that of GlidCop Al60.