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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
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.
LSTM-XGBoost 앙상블 모형을 이용한 월별 전력판매량 예측 알고리즘
김경환(Kyeong-Hwan Kim),조승민(Seung-Min Cho),송경빈(Kyung-Bin Song) 대한전기학회 2024 전기학회논문지 Vol.73 No.5
Electric power sales forecasting is important from various perspectives, including the nation, power producers, and sellers. At the national level, it serves as foundational information for electricity supply efficiency, energy policy establishment, and integration of renewable energy. Power producers utilize it for optimal operation and planning of power plants, and decisions on power plant expansion and investment. Sellers can use it for monthly energy balance evaluation, operational efficiency improvement, and financial analysis. In this paper, we analyze factors that affect electric power sales to predict medium and long-term electricity sales volume, and based on this, input variables that have a high correlation with monthly electricity sales volume are selected. Then, the LSTM-based deep neural network model and XGBoost model are learned using the selected data. We construct an ensemble model by combining the monthly forecasts of each model using a voting method and present an algorithm to predict electricity sales for the next 24 months. The proposed ensemble model showed improved performance over the prediction model using a single technique.
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.
Rotor Head 내부에 장착되는 Bracket 의 진동에 관한 연구
김경환(Kyeong-Hwan Kim),이영신(Young-Shin Lee),한재도(Jae-Do Han) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
Bracket will be used when installing a new equipment on the helicopter. Equipment should operate normally on all kinds of operating conditions. Therefore, the design of brackets should be done properly. In this paper, structure and vibrations analysis on bracket was performed by Ansys program.
Rotor Head 내부에 장착되는 Bracket 의 진동 및 응력해석에 관한 연구
김경환(Kyeong-Hwan Kim),이영신(Young-Shin Lee),한재도(Jae-Do Han) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Bracket will be used when installing a new equipment on the helicopter. Equipment should operate normally on all kinds of operating conditions. Therefore, the design of brackets should be done properly. In this paper, structure and vibrations analysis on bracket was performed by Ansys program.