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김광연,이승진,지선영,배수진,송유림,윤언정,박선빈,송종국,손태진,손재동,김우현,양주혜,박선동,김상찬,김영우,박광일,Kim, Kwang Yeon,Lee, Seung Jin,Jee, Seon Young,Bae, Su Jin,Song, Yu Rim,Yun, Un-Jung,Bak, Seonbeen,Song, Jong Kuk,Son, Tae Jin,Son, Jae- 대한한의학방제학회 2021 大韓韓醫學方劑學會誌 Vol.29 No.2
Objectives : This study investigated cellular-protective effects of Nardotidis seu Sulculii Concha water extract (NSCE) against oxidative stress induced by arachidonic acid (AA)+iron or tert-butylhydroperoxide (tBHP). Methods : In vitro, MTT assay was assessed for cell viability, and immunoblotting analysis was performed to detect expression of AMP-activated kinase (AMPK) signaling pathway and autophagy related proteins. In vivo, mice were orally administrated with the aqueous extract of NSCE of 500 mg/kg for 3 days, and then injected with CCl<sub>4</sub> 0.5 mg/kg body weight to induce acute damage. The level of liver damage was measured by serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) analysis. Results : Treatment with NSCE inhibited cell death induced by AA+iron and tBHP. NSCE induced the phosphorylation of AMPK, and this compound also induced the phosphorylation of LKB1, an upstream kinase of AMPK, and Acetyl-CoA carboxylase (ACC), a primary downstream target of AMPK. NSCE increased the protein levels of autophagic markers (LC3II and beclin-1) and decreased the phosphorylation of mammalian target of rapamycin (mTOR) and simultaneously increased the phosphorylation of unc-51-like kinase-1 (ULK-1) in time-dependent manner. Conclusions : NSCE has the ability 1) to protect cells against oxidative stress induced by AA+iron or tBHP. NSCE 2) to activate AMP-activated protein kinase (AMPK), and 3) to regulate autophagy, an important regulator in cell survival.
김광연(Kwang Yeon Kim),김일건(Il Kun Kim),정성원(Sung Won Jung),박건환(Keon Hwan Park),박영진(Young Jin Park) 대한외과학회 2007 Annals of Surgical Treatment and Research(ASRT) Vol.73 No.1
Purpose: With the gradual changes in the diet, the incidence of colonic diverticular disease, particularly that of the left side colon, has increased rapidly in Korea. The aim of this study was to evaluate the clinical features of diverticular disease and to compare the differences in treatment between right and left colonic diverticulitis. Methods: The hospital records of 67 patients with diverticulitis were reviewed retrospectively. Results: The incidence of right side colonic diverticulitis was 2.5 times higher than that of the left side (48 and 19 cases, respectively). The mean age of the patients was 51.3 years with a male to female ratio of 2.1:1. The left side colonic diverticulitis developed at an older age than that of the right side (mean age of 47.2 and 58.7 years, respectively, P=0.03). Seventeen out of 48 (35.4%) right and 8 out of 19 (42.1%) left colonic diverticulitis patients were treated surgically. The ratio of surgical treatment was not different according to the location of diverticulitis (P=0.61). The age and gender of the patients or leucocytosis at the time of the diagnosis were not associated with the risk of surgical treatment. The presence of fever and high-grade sepsis on the CT scan(Hinchey grade) were significant risk factors for surgery. The symptom duration was longer in the surgically treated group than in the conservative treatment group in left colonic diverticulitis (P=0.03). Most surgical procedures for right colonic diverticulitis were a single-stage colon resection (16 out of 17 cases), whereas staged procedures including Hartmann"s operation (3 cases) and proximal diversion (2 cases) with abscess drainage were performed in 5 out of the 8 left colonic cases. Postoperative complications were more frequent in the left colon cases. Conclusion: The left colon is a relatively rare site for diverticulitis in Korea. However, diverticulitis of this section of the colon requires more complicated surgical treatment and is associated with a higher rate of complications than that of the right colon. The earlier application of diagnostic work up might be necessary for patients suspected of having left colonic diverticulitis because a delayed diagnosis is associated with a risk of surgical treatment.
디젤 배기 내 질소산화물 저감을 위한 엔진작동, DOC-SCR 후처리 과정의 일관 모델링 및 운전모드에 따른 De-Nox 특성 해석
김광연(Kwang-yeon Kim),윤웅섭(Woong-sup Yoon) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
NOx removal efficiency by a DOC-SCR system and the effect of NH₃/NOx ratio on the de-NOx performance was numerically-theoretically investigated. An de-NOx analysis method was incorporated with an engine simulator for a unified treatment of an emission removal process. Thermochemical model of NO-NO₂ conversion over Pt-based catalyst and SCR reaction over vanadium-based catalyst and NH₃ reductant was formulated and validated with experiments. A commercial code WAVE provides engine-out emission state of ESC 13 modes. The results show that a SCR size has little effects on a De-NOx efficiency when a DOC is installed. And as a SCR size smaller and an engine speed higher, the effect of a DOC on a De-NOx efficiency is lager. The maximum increasement of a DOC-SCR system's De-NOx efficiency for a SCR's De-NOx efficiency is about 200%.
김광연(Kwang-Yeon Kim),박정우(Jung-Woo Park),탁민제(Min-Jea Tahk) 한국항공우주학회 2008 韓國航空宇宙學會誌 Vol.36 No.10
본 논문에서는 3차원 일대일 충돌 감지 충돌 회피 및 경로점 유도를 위한 알고리듬에 대해 다룬다. 항공기는 질점 모델로 가정하였다. 충돌 감지는 최근접점까지 남은 시간과 그 때의 거리를 기준 값과 비교하여 수행하였다. 충돌 회피는 최적 제어 이론을 이용하여 최종 시간에서의 상대 거리를 최대화하는 가속도 입력을 계산하여 수행하였다. 경로점 유도는 잘 알려진 비례 항법유도를 적용하였다. 제안된 알고리듬의 성능은 두 개의 시나리오를 통하여 검증하였다. This paper presents the development of a real-time algorithm for collision detection, collision avoidance and guidance to way-point. Three-dimensional point-mass aircraft models are used. For collision detection, time of closest point of approach(CPA) and distance at CPA are compared to threshold values. For collision avoidance, optimal acceleration input which maximizes the terminal relative distance is calculated based on optimal control theory. For guidance to way-point, proportional navigation guidance, the well-known method, is used. Two scenarios of encounter situation are illustrated to validate performance of proposed algorithm.