• 대한기계학회논문집
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• 제11권3호
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• pp.444-453
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• 1987

본 연구에서는 난류구조에 대한 유선곡률의 영향을 명확히 반영하는 적절한 곡률수정 2-방정식모델을 개발하고자 한다. 이 연구에서 제안된 모델의 타당성은 다 음의 2차원 재순환유동에 대한 실험결과와 계산결과의 비교를 통해서 입증될 것이다. (1) Moss와 Bake에 의하여 맥동열선 풍속계로 측정된 두꺼운 수직벽주위의 유동` (2) 레이저 도플러 속도계로 Fraser와 Siddig에 의해 측정된 얇은 수직벽유동` (3)맥동열 선 풍속계로 Eaton이 실험한 후면벽유동` (4)맥동열선 풍속계로 Moss와 Baker가 측정 한 전면벽유동. 새로운 곡률수정 2-방정식모델은 2장에서 설명되고 있으며, 3장에서 는 경계조건과 수치계산 과정이 간단이 기술되어 있다. 그 뒤에 4장에는 계산결과와 실험치에대한 비교검토가 설명되어 있고 마지막으로 5장에서는 본 연구에 대한 결론을 맺고 있다.

• Korean Journal of Acupuncture
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• 제29권2호
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• pp.271-289
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• 2012

Objectives : Ganoderma lucidum(Ganoderma or lingzhi, 靈芝) is a well-known oriental medical mushroom containing many bioactive compounds. The possible mechanisms involved in its effects on cancer cells remain to be elucidated. In the present study, the anti-proliferative and apoptotic activities of the G. lucidum ethanol extract(GEE), in AGS human gastric cancer cells were investigated. Methods : It was found that exposure of AGS cells to GEE resulted in the growth inhibition in a dose and time dependent manner as measured by trypan blue count and MTT assay. The anti-proliferative effect of GEE treatment in AGS cells was associated with morphological changes and formation of apoptotic bodies, and the flow cytometry analysis confirmed that GEE treatment increased the populations of apoptotic-sub G1 phase. Growth inhibition and apoptosis of AGS cells by GEE were connected with a concentration and time-dependent up-regulation of tumour necrosis factor-related apoptosis-inducing ligand(TRAIL) expression. Results : The levels of XIAP and survivin expression, members of IAP family proteins, were gradually down-regulated by GEE treatment. However other members of IAP family proteins such as cIAP-1 and cIAP-2 remained unchanged in GEE-treated AGS cells. GEE treatment also induced the proteolytic activation of caspase-3, caspase-8 and caspase-9 and a concomitant degradation of poly(ADP-ribose) polymerase(PARP) protein, a caspase-3 substrate protein. Additionally, GEE-induced apoptosis was associated with the inhibition of Akt activation in a concentration and time-dependent manner, and pre-treatment with LY294002, a phosphoinositide 3-kinase(PI3K)/Akt inhibitor, significantly increased GEE-induced growth inhibition and apoptosis. Conclusions : Therefore, G. lucidum has a strong potential as a therapeutic agent for preventing cancers such as gastric cancer cells.

• 한국시뮬레이션학회논문지
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• 제24권4호
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• pp.77-88
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• 2015

본 논문은 작업별 위치기반 지수학습 효과를 갖는 2-에이전트 단일기계 스케줄링 문제를 고려한다. 에이전트 A는 가중 완료 시간의 합을 최소화하며, 에이전트 B는 총소요시간에 대한 상한 값을 만족하는 조건을 갖는다. 본 연구에서는 먼저 우수해/가능해에 대한 특성을 개발하고, 이를 이용하여 최적 해를 찾기 위한 분지한계 알고리즘을 설계한다. 또한 근사 최적 해를 구하기 위해 6가지 다른 초기해 생성 방법을 이용한 시뮬레이티드 어닐링 알고리즘을 제안한다. 수치 실험을 통해 제안된 알고리즘의 우수한 성능을 검증한다. 실험 결과, 다른 초기해 생성 방법들 간에는 %errors 차이가 유의하게 발생하지 않았으며, 에이전트 A의 작업 순서를 무작위로 생성할 때 성능이 좋아짐을 발견하였다. 반면에, 에이전트 B의 초기해 생성 방법은 성능에 영향을 미치지 않았다.

• 한국식생활문화학회지
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• 제33권5호
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• pp.464-471
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• 2018

Purpose: This study examined the effects of ${\alpha}$-lipoic acid in diluted solvents on cell growth in 3T3-L1 cells according to the treated concentration and times. Methods: Adipocyte 3T3-L1 cell were cultured. Confluent cells underwent starvation with SFM for 1 day and then were cultured in a medium containing various concentrations 0, 100, 200, and $400{\mu}mol/L$ of ${\alpha}$-lipoic acid. The cell viability was measured using the EZ Cytox assay kit. In addition, the effect of ${\alpha}$-lipoic acid of diluted solvents on the cell growth in 3T3-L1cells was examined according to the treated concentration and times. Results: The ${\alpha}$-lipoic acid diluted ethanol inhibited cell proliferation in a dose and time dependent manner. The ${\alpha}$-lipoic acid diluted ethanol induced adipocyte 3T3-L1 cells proliferation with an adipocyte inducer. In addition, ${\alpha}$-lipoic acid inhibited adipocyte 3T3-L1 growth in a dose and time dependent manner (p<0.05). Conclusion: This study showed that a treatment with ${\alpha}$-lipoic acid diluted ethanol inhibits cell growth of, adipocyte 3T3-L1 cells induced with an adipocyte inducer, ($200{\mu}mol/L$ of ${\alpha}$-lipoic acid) treated for 48 hr.

• Wind and Structures
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• 제27권6호
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• pp.381-397
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• 2018

Nonlinear behavior in fluid-structure interaction (FSI) of bridge decks becomes increasingly significant for modern bridges with increasing spans, larger flexibility and new aerodynamic deck configurations. Better understanding of the nonlinear aeroelasticity of bridge decks and further development of reduced-order nonlinear models for the aeroelastic forces become necessary. In this paper, the amplitude-dependent and neutral angle dependent nonlinearities of the motion-induced loads are further highlighted by series of computational fluid dynamics (CFD) simulations. An effort has been made to investigate a semi-analytical time-domain model of the nonlinear motion induced loads on the deck, which enables nonlinear time domain simulations of the aeroelastic responses of the bridge deck. First, the computational schemes used here are validated through theoretically well-known cases. Then, static aerodynamic coefficients of the Great Belt East Bridge (GBEB) cross section are evaluated at various angles of attack, leading to the so-called nonlinear backbone curves. Flutter derivatives of the bridge are identified by CFD simulations using forced harmonic motion of the cross-section with various frequencies. By varying the amplitude of the forced motion, it is observed that the identified flutter derivatives are amplitude-dependent, especially for $A^*_2$ and $H^*_2$ parameters. Another nonlinear feature is observed from the change of hysteresis loop (between angle of attack and lift/moment) when the neutral angles of the cross-section are changed. Based on the CFD results, a semi-analytical time-domain model for describing the nonlinear motion-induced loads is proposed and calibrated. This model is based on accounting for the delay effect with respect to the nonlinear backbone curve and is established in the state-space form. Reasonable agreement between the results from the semi-analytical model and CFD demonstrates the potential application of the proposed model for nonlinear aeroelastic analysis of bridge decks.

• 대한화장품학회지
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• 제46권3호
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• pp.253-263
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• 2020

활성산소종(reactive oxygen species, ROS)은 우리 몸의 항상성 유지에 있어 중요한 역할을 한다. 그러나 과도한 ROS의 생성은 단백질, 지질, 핵산과 같은 세포 구성성분을 손상시키고 피부노화를 촉진시킨다. 이에 본 연구에서는 과도한 산화 스트레스를 예방하기 위해 Chungsimyeonja-um (CSYJE)의 항산화 효과를 확인하였다. 먼저 DPPH 및 ABTS assay를 실시하여 CSYJE의 항산화 효과를 확인한 결과 농도 의존적으로 radical 소거 활성을 확인하였다. 세포생존율 확인을 위해 MTT assay를 실시한 결과 1,000 ㎍/mL 농도에서 세포 독성이 없음을 확인하였다. 항산화 관련 단백질인 nuclear-E2-related factor 2 (Nrf2), Heme oxygenase-1 (HO-1)의 발현 수준을 확인하기 위해 western blotting을 실시한 결과 농도 의존적으로 발현이 증가하는 것을 확인하였다. 세포 내 ROS유발 물질인 lipopolysaccharide (LPS)로 ROS를 유도한 후, ROS생성 억제효과를 확인하기 위해 DCF-DA 염색법을 실시한 결과 농도 의존적으로 ROS 생성 억제효과를 확인하였으며 ROS의 생성으로 인한 염증성 사이토카인과 염증인자의 mRNA발현 수준을 확인하기 위해 real-time RT-PCR을 실시한 결과 농도 의존적으로 염증성 사이토카인과 염증인자의 mRNA 발현을 억제시켰다. 따라서, 본 연구는 Nrf2/HO-1 신호 전달 경로 활성을 통해 CSYJE의 항산화효과를 확인했으며 이는 CSYJE가 활성산소를 억제하여 항산화 화장품의 재료로서 사용될 수 있음을 시사한다.

• 동의생리병리학회지
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• 제16권2호
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• pp.338-342
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• 2002

In order to evaluate the effect of Ginseng Radix(GR) against endocrine disrupting chemicals(EDC), cultured mouse osteoblasts were preincubated with various concentrations of GR extract before the exposure of Bisphenol A for 12 hours. Cytotoxic effect of Bisphenol A was measured by the XTT assay. In addition, the protective effect of GR over Bisphenol A-induced cytotoxicity on osteoblasts was assessed by the DNA and protein synthesis in these cultures. The results were as follows : Osteoblastic cell viability was decreased in dose and time dependent manner after exposed to various concentrations of Bisphenol A. Midcytotoxicity value(MCV50) of Bisphenol A was determined at 6μM Bisphenol A after osteoblasts were grown for 12 hours in the media containing various concentrations of Bisphenol A. Amount of DNA synthesis was increased in dose-dependent manner after cultured osteblasts were pretreated with GR for 2hrs before exposure to Bisphenol A for 12 hours. Amount of protein synthesis was increased in dose-dependent manner after cultured osteoblasts were pretreated with GR for 2 hours before exposure of Bisphenol A for 12 hours. From these results, it is suggested that Bisphenol A was highly toxic by the decrease of the cell viability, and GR is effective in the prevention of Bisphenol A-induced cytotoxicity by the increase of DNA and protein syntheses in cultured mouse osteoblasts.

• The Korean Journal of Physiology and Pharmacology
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• 제12권4호
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• pp.137-142
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• 2008

Ceramide has emerged as a novel second messenger for intracellular signalling. It is produced from sphingomyelin and is involved in the control of cell differntiation, proliferation, and apoptosis. $C_2$-ceramide, short chain ceramide, plays a role in mediating contraction of cat esophageal smooth muscle cells. We examined the effect of synthesized ceramide analogues on the $C_2$-ceramide and ACh-induced contraction in esophageal smooth muscle cells isolated with collagenase. CY3523, CY3525, or CY3723 inhibited $C_2$-ceramide induced contraction, in a time dependent manne. Each analogue also inhibited the contraction in concentration dependent manners. CY 3523, CY 3525, and CY 3723 had no effect to the contraction induced by PMA. The inhibition with CY3523, CY3525 and CY3723 on the $C_2$-ceramide induced contraction was recovered by PMA. These analogues decreased the density of MAPK bands (p44/42 or p38) in the western blot. These results suggest that ceramide analogues can inhibit $C_2$-ceramide induced contraction via PKC and MAPK dependent pathway.

• 동의생리병리학회지
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• 제22권5호
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• pp.1322-1329
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• 2008

Mulberry has been reported to contain wide range of polyphenols and have chemopreventive activity. However, little has been known regarding the effect of mulberry fruits on cell viability in human glioma cells. The present study was undertaken to examine the effect of mulberry fruit (Mar; Fructus) on cell viability and to determine its underlying mechanism in human glioma cells. Cell viability and cell death were estimated by MTT assay and trypanblue exclusion assay, respectively. Reactive oxygen species (ROS) generation was measured using the fluorescence probe DCFH-DA. The mitochondrial transmembrane potential was measured with $DiOC_6$(3). Bax expression and cytochrome c release were measured by Western blot analysis. Caspase activity was estimated using colorimetric kit. Mori Fructus resulted in apoptotic cell death in a dose- and time-dependent manner. Mori Fructus increased ROS generation and the Mori Fructus-induced cell death was also prevented by antioxidants, suggesting that ROS generation plays a critical role in Mari Fructus-induced cell death. Western blot analysis showed that Mori Fructus treatment caused an increase in Bax expression, which was inhibited by the antioxidant N-acetylcysteine (NAC). Mori Fructus induced depolarization of mitochondrial membrane potential and its effect was inhibited by the antioxidants NAC and catalase. Mori Fructus induced cytochrome c release, which was inhibited by NAC. Caspase activity was stimulated by Mori Fructus and caspase inhibitors prevented the Mori Fructus-induced cell death. These findings suggest that Mori Fructus results in human glioma cell death through ROS-dependent mitochondrial pathway in human glioma cells.

• 한국산학기술학회논문지
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• 제10권11호
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• pp.3473-3479
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• 2009

비펩타이드성 안지오텐신 수용체 길항제로 새롭게 개발된 KR-31081에 대한 생체 내 활성을 세가지 동물모델에서 검증하였다. 척수장애 동물모델에서 KR-31081은 로사탄보다 40배 이상의 경쟁적인 혈압강하 효과를 나타내었으며, 신성고혈압쥐 모델에서 KR-31081은 로사탄보다 10배 가량의 지속형 효과를 나타내었다. 또한 개실험에서 구강 투여한 KR-31081은 로사탄보다 20배 이상의 지속적인 혈압강하 효과를 나타내었다. 실험에 사용된 동물 모델 시스템에서 다른 혈관조절물질들과 상호작용을 하지 않는 것으로 나타난 KR-31081은 향후 고혈압 및 혈관질환에 대한 연구 및 진단에 활용될 수 있을 것이라고 판단된다.