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Magnetotransport of lateral Py/Pt/Py spin valve device
Han, Giju,Chang, Joonyeon,Eom, Jonghwa,Kim, Hyungjun,Kim, Young Keun,Han, Suk-Hee WILEY-VCH Verlag 2007 Physica Status Solidi. B Vol.244 No.12
<P>Spin injection and accumulation have been investigated for Py/Pt/Py lateral spin valves with various channel length. Clear spin valve effects were found at antiparallel magnetic configuration of two ferromagnetic electrodes. The observation of memory effect suggests the spin valve effect observed in Pt channel is resulted from effective spin injection and detection. The magnitude of spin valve signal decreases as the channel length increases. The measurement yields that spin diffusion length and spin injection polarization of Pt channel is 120 nm and 18% at 5K. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)</P>
Han, Woobeom,Kim, Jonghwa,Kim, Bumsuk Elsevier 2018 RENEWABLE ENERGY Vol.115 No.-
<P><B>Abstract</B></P> <P>Contamination and erosion at the leading edge of blade tips adversely affect the annual energy production (AEP) of wind turbines. Obtaining pertinent quantitative data would help in the efficient planning of operations and maintenance of these turbines. In this study, to quantitatively analyze the effects of contamination and erosion on the aerodynamic performance of a blade tip airfoil (NACA 64-618) and in turn on the AEP loss of wind turbines, transient computational fluid dynamics simulations and AEP calculations were performed for a 5-MW National Renewable Energy Laboratory wind turbine. The simulations indicated that depending on the severity of the conditions, contamination and erosion conditions reduced and increased the lift and drag coefficients, respectively, of the blade by up to 53% and 314%. Contamination and erosion conditions reduced AEP by 2%–3.7%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effects of leading edge damage on the performance of wind turbines were examined. </LI> <LI> The L.E damage reduces the aerodynamic coefficients and the power output of the blade. </LI> <LI> Contamination and erosion conditions reduced AEP by 2%–3.7%. </LI> </UL> </P>
( Jonghwa Kim ),( Sohee Kang ),( Soohyun Park ),( Ju-yeon Cho ),( Won Sohn ),( David A. Brenner ),( Yong-han Paik ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1
Aims: In hepatic fibrogenesis hepatic stellate cell (HSC) is a major cell type responsible for producing a major profibrogenic cytokine TGF-b, and connective tissue growth factor (CTGF), a major fibrogenic mediator in several organs. The multi-functional nature of TGF-b signaling in hepatic fibrogenesis is still elusive. At the previous The Liver Week(2015) we reported that Pyk2 is essential for TGF-b-mediated, Smad-independent CTGF induction. Pyk2 is known to be calcium- sensitive, and TGF-b was reported to increase intracellular calcium level. Therefore, we investigated the relation between intracellular calcium levels and pro-fibrogenic TGF-b/Pyk2 axis in hepatic stellate cell. Methods: Immortalized human stellate cell line, LX-2, has been cultured. After TGF-b treatment, expression of CTGF and a-SMA were assessed with RT-PCR and western blot. Pharmacological inhibitor and siRNA-mediated knockdown were used to modulate the activities and expression levels of protein. Intracelllular calcium mobilization was measured with Fura-4/AM. Activation of Pyk2 was addressed in western blot using different phosphorylation site-specific antibodies. Results: CTGF expression was up-regulated within 1hr in TGF-b stimulated LX-2. This up-regulation was greatly suppressed by siRNA-mediated knockdown and pharmacological inhibitor of Pyk2. TGF-b treatment increased phosphorylation of Pyk2 on tyrosine 402, 579/580, and 881. Consistent with the previous reports, TGF-b increased intracellular calcium concentration in Fura-4-preloaded LX-2. CTGF induction by TGF-b was blocked in dose dependent manner by pre-treatment with BAPTA-AM, an intracellular calcium chelator, while A23187, a calcium ionopore, increased CTGF induction even in the absence of TGF-b, suggesting that increase of intracellular calcium level is enough to induce CTGF expression. In addition, A23187 increased phosphorylation of Pyk2, and CTGF induction by A23187 is also greatly reduced by siRNA of Pyk2. Pre-treament of LX-2 with Nifedipine (an L-type calcium channel blocker) suppressed CTGF induction by TGF-b in dose-dependent manner, while FPL64176 (L-type channel activator) increased CTGF expression without TGF-b. The CTGF up-regulations by TGF-b, A23187, and FPL64176 were all suppressed by siRNA-mediated knockdown and pharmacological inhibitors of Pyk2. Conclusions: In hepatic stellate cell, TGF-b increases the intracellular calcium level through L-type calcium channel, leading to downstream Pyk2 signaling for CTGF induction.
촉매의 종류에 따른 lactic acid의 에스테르화 반응의 연구
한지윤,김종화,이상화 한국공업화학회 2003 응용화학 Vol.7 No.2
Esterification of lactic acid with butanol catalyzed by Amberlyst-type ion exchange resin and sulfuric acid was carried out in a batch reactor under temperature ranges of 100∼130℃. The reaction rate was significantly influenced by water contents (wt%), alcohol/lactic acid mole ratio, kinds of catalysts and reaction temperature. Esterification of the lactic acid with butanol is promoted by removing residual water continuously using recycle reactive distillation(above 100℃). The presence of water strongly inhibits the conversion of lactic acid to butyl lactate due to equilibrium-limited reaction. Other operation parameters were also investigated in terms of lactic acid conversion.
시민의 복지태도와 나눔행동에 관한 연구: 기부와 자원봉사 참여를 중심으로
이종화(Jonghwa Lee),장재혁(Jaehyuck Jang),한민희(Min Hee Han) 연세대학교 사회복지연구소 2019 한국사회복지조사연구 Vol.60 No.-
본 연구의 목적은 시민의 복지태도가 나눔행동에 미치는 영향력을 확인하는 것이다. 이를 위해 서울시와 서울연구원이 서울시 거주 3,019가구를 조사한 2015 서울복지실태조사 데이터를 활용해 시민들이 가진 4가지 복지태도 : 성장과 분배, 선택적 복지와 보편적 복지, 복지지출에 대한 개인과 정부의 책임, 정부복지정책 신뢰수준이 기부와 자원봉사 참여에 미치는 영향을 확인하였다. 분석방 법으로는 두 개의 이항종속변수 사이에 존재할 수 있는 상호의존성을 반영해 효율적인 추정을을 가능하게 해주는 이변량 프로빗 모형을 사용하였다. 연구결과 성장보다 분배를 중요하게 인식할수 록, 정부복지정책에 대한 신뢰가 높을수록 기부에 적극적으로 참여하였고, 복지지출에 대한 정부의 책임을 중요하게 인식할수록 기부에 소극적인 것으로 나타났다. 그리고, 보편적 복지 정책에 대한 중요성 중요하게 인식할수록 자원봉사 참여에 소극적인 것으로 나타났다. 본 연구는 연구의 성과가 부족한 복지에 대한 개인 인식과 나눔 행동 사이의 관계에 대해 실증적인 분석을 하였고, 기부와 자원봉사 행동에 대한 상호의존성을 반영할 수 있는 분석방법을 소개했다는 점에서 의의를 갖는다. The purpose of the study is to identify the influence that the citizen’s attitude of welfare exerts on philanthropic behaviors. Specifically, the study has identified the influences that the citizen’s attitude on the four things, that is, growth and distribution, targeted welfare and universal welfare, the responsibility for welfare expenses, and the trust in the governmental welfare policy, exert on donations and participation in volunteer work. For this purpose, the study used the data from the 2015 Seoul Welfare Survey which was conducted with 3,019 households in Seoul. And for its analytical method, the study employed Bivariate Probit model which enables efficient estimation by reflecting the interdependence that may exist between the two binomial dependent variables. The study showed that people who consider welfare distribution more importantly than economic growth and those who put greater trust in the governmental welfare policy more actively participated in donation, and that those who more strongly believe the governmental responsibility for welfare were more passive in participating in donation, and that those who more strongly believe the importance of universal welfare policy were more passive in participating in volunteer activities. This study has performed an empirical analysis on the relationship between the public perception of welfare and philanthropic behaviors and is significant in that it has introduced a new analytical method that can reflect the interdependence between donation and volunteer participation.