• BMB Reports
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• 제32권5호
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• pp.419-428
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• 1999

Tumor necrosis factor (TNF) receptor members have unique structures composed of 2-4 cysteine - rich pseudorepeats in the extracellular domain. On ligation by trimeric ligand molecules, oligomerization of three receptor molecules occurs, which in turn activates the receptor and recruits intracellular signaling molecules to the cytoplasmic tail to initiate biological events. Recently, the numbers of tumor necrosis factor receptor and ligand family members have been rapidly expanding. Functional characterization of the new members has indicated redundant roles with other known members as well as provided insights into novel functions. In particular, identification of soluble decoy receptors which have the ability to bind multiple ligands highlights a complex control mechanism of immune responses by these molecules. Studies of the new members have also revealed that the TNF receptor and ligand family members play an important role in other than the immune system.

• 천문학회보
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• 제37권1호
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• pp.85.1-85.1
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• 2012

In this study we use three-dimensional magnetohydrodynamic simulations of flux emergence from solar subsurface layer to corona. In order to study the twist parameter of magnetic field we compare the simulations for strongly twisted and weakly twisted cases. Based on the results, we derive a flux expansion factor of selected flux tubes which is a ratio of expanded cross section to the one measured at the footpoint of the flux tube. To understand the effect of flux expansion factor, we make a comparison between magnetic field configuration and the expansion factor. By using a fitting function of hyperbolic tangent we derive noticeable correlations among the strength of the vertical magnetic field, current density and expansion factor. We discuss what these results tell about the relationship between the twist of emerging field and the mechanism for the solar wind.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.108-109
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• 2005

The aim of Port State Control(PSC) system is recognized as a proficient mechanism in preventing coastal traffic accident and protecting marine environment. Recently, PSC system is focused on human factor of International Maritime Convention, especially ILO and STCW Convention by considering many accidents resulted from human factor. Therefore, we have to understand of Consolidated Maritime Labour Convention which describes employment conditions and social welfare policy, the rights about the lowest wages, the overdue wages, the unemployment protection. a disaster reward, etc and STCW Convention which describes standards of training, certification and watchkeeping for seafarers. The aim of this study is to recognize inspection points about human factor of these Conventions. .

• 대한의생명과학회지
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• 제20권2호
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• pp.56-61
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• 2014

This study attempted to confirm the antioxidative potential of luteolin against tert-butyl hydroperoxide (t-BHP) induced oxidative damage and to investigate its molecular mechanism related to glutathione (GSH)-dependent enzymes in HepG2 cells. Treatment with luteolin resulted in attenuation of t-BHP induced generation of reactive oxygen species (ROS) and oxidative stress-mediated cell death. In addition, accelerated expression of GSH-dependent antioxidative enzymes, glutathione peroxidase (GPx) and glutathione reductase (GR), and heme oxygenase (HO)-1, as well as strengthened GSH content was induced by treatment with luteolin, which was in accordance with increased nuclear translocation of nuclear factor-erythroid 2 p45-related factor 2 (Nrf2), a transcription factor for phase 2 enzymes, in a dose-dependent manner. These results suggest that the cytoprotective potential of luteolin against oxidative damage can be attributed to fortified GSH-mediated antioxidative pathway and HO-1 expression through regulation of Nrf2 in HepG2 cells.

• BMB Reports
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• 제51권8호
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• pp.388-393
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• 2018

The activating transcription factor (ATF) 4 belongs to the ATF/CREB (cAMP Response Element Binding bZIP [Basic Leucine Zipper]) transcription factor family, and plays a central role in the UPR (Unfolded Protein Response) process in cells. The induction of ATF4 expression has previously been shown to increase the replication of HIV-1. However, the detailed mechanism underlying this effect and the factors involved in the regulation of ATF4 function are still unknown. Here, we demonstrate first that knocking out ATF4 using siRNA shows a strong negative effect on HIV-1 production, indicating that ATF4 is a functional positive cellular factor in HIV-1 production. To determine the mechanism by which ATF4 regulates the HIV-1 life cycle, we assessed the effect of the overexpression of wild type ATF4 and its various derivatives on HIV-1 LTR-mediated transcriptional activation and the production of HIV-1 particles. This effect was studied through co-transfection experiments with either reporter vectors or proviral DNA. We found that the N-terminal domains of ATF4 are involved in HIV-1 LTR-mediated transcriptional activation, and thus in HIV-1 production.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.369-385
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• 2002

Ductility capacity is comprehensively studied for steel moment-resisting frames. Local, story and global ductility are being considered. An appropriate measure of global ductility is suggested. A time domain nonlinear seismic response algorithm is used to evaluate several definitions of ductility. It is observed that for one-story structures, resembling a single degree of freedom (SDOF) system, all definitions of global ductility seem to give reasonable values. However, for complex structures it may give unreasonable values. It indicates that using SDOF systems to estimate the ductility capacity may be a very crude approximation. For multi degree of freedom (MDOF) systems some definitions may not be appropriate, even though they are used in the profession. Results also indicate that the structural global ductility of 4, commonly used for moment-resisting steel frames, cannot be justified based on this study. The ductility of MDOF structural systems and the corresponding equivalent SDOF systems is studied. The global ductility values are very different for the two representations. The ductility reduction factor $F_{\mu}$ is also estimated. For a given frame, the values of the $F_{\mu}$ parameter significantly vary from one earthquake to another, even though the maximum deformation in terms of the interstory displacement is roughly the same for all earthquakes. This is because the $F_{\mu}$ values depend on the amount of dissipated energy, which in turn depends on the plastic mechanism, formed in the frames as well as on the loading, unloading and reloading process at plastic hinges. Based on the results of this study, the Newmark and Hall procedure to relate the ductility reduction factor and the ductility parameter cannot be justified. The reason for this is that SDOF systems were used to model real frames in these studies. Higher mode effects were neglected and energy dissipation was not explicitly considered. In addition, it is not possible to observe the formation of a collapse mechanism in the equivalent SDOF systems. Therefore, the ductility parameter and the force reduction factor should be estimated by using the MDOF representation.

• 동의생리병리학회지
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• 제30권4호
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• pp.250-256
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• 2016

The prevalence of renal disease is increased with the overweight and obesity. High fat diet-associated oxidative stress increases production of reactive oxygen species (ROS) and induces apoptosis. There are two types of antioxidant defense mechanisms for oxidative stress. One is the enzyme defense mechanism by antioxidant enzymes such as superoxide dismutase (SOD), and catalase (CAT). The other is non-enzyme defense mechanism by signaling molecules such as nuclear factor-like 2 (Nrf-2), HO-1. In this study, we induced obesity in mice with high fat diet for six weeks and thereafter administered orally Viola mandshurica for 4 weeks. V. mandshurica is known to clear heat, detoxify and cool blood, and subside a swelling effect. In the V. mandshurica administered group, the immunoreactive signal of the Tunel staining was weaker than that of obesity group. Proapoptotic Bax, caspase 3 immunoreactives of the V. mandshurica administered group was lower than those of obesity group, whereas anti-apoptotic Bcl-2 immunoreactity was higher in the V. mandshurica administered group. Antioxidant enzyme mechanism such as superoxide dismutase 2 (SOD2), catalase (CAT) immunoreactives of the V. mandshurica administered group and Antioxidant non-enzyme mechanism such as Nuclear factor-like 2 (Nrf2), Heme Oxygenase 1 (HO-1) immunoreactives of the V. mandshurica administered group was higher than those of obesity group. These results demonstrate that V. mandshurica had the antioxidant and anti-apoptosis effects on obese mice.

• 대한수학교육학회지:수학교육학연구
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• 제14권3호
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• pp.239-266
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• 2004

본 연구는 기존의 수학적 오류에 대한 연구들이 취했던 학생들의 현재 상태를 바탕으로 다양한 오류를 분석하는 방식이 아니라, 학생들의 문제해결과정에서 나타나는 수학적 오류를 인지심리학의 관점에서 분석가능한지를 탐색하는 것을 목적으로 한다. 이에, 본 연구는 Pauscal-Leone의 신피아제 이론을 중심으로 Schoenfeld의 구조 분석 단계(levels of analysis and structure)모형과 개념적, 인과적 관계의 이해를 형식화하는 도구로서 퍼지 인지 맵(Fuzzy Cognitive Map)을 활용하여 학생들의 증명 문제해결 과정에서 나타나는 오류를 분석하고 오도요인을 진단하였다. 연구 결과, 주어진 명제에서 정보를 해석할 때 F조작자가 강하게 활성화되어 나타나는 오도 요인으로 인하여 학생들은 증명에 필요한 개념노드를 충분하게 인출하지 못하거나 인과관계가 없는 개념노드를 나름대로 논리적으로 연결하여 잘못된 증명을 하고 있었다. 오류와 관련된 인지구조는 학생 나름대로의 논리적 알고리듬에 의한 LC 학습의 결과로 형성된 LC 학습구조로 볼 수 있다.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2613-2620
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• 2023

Excellent thermal neutron absorption performance of boron expands the potential use of boron rich slag to prepare epoxy resin matrix nuclear shielding composites. However, shielding attenuation behaviors and mechanism of the composites against gamma rays are unclear. Based on the radiation protection theory, Phy-X/PSD, XCOM, and ⁶⁰Co gamma ray source were integrated to obtain the shielding parameters of boron rich slag/epoxy resin composites at 0.015-15 MeV, which include mass attenuation coefficient (µ_t), linear attenuation coefficient (µ), half value thickness layer (HVL), electron density (N_eff), effective atomic number (Z_eff), exposure buildup factor (EBF) and exposure absorption buildup factor (EABF).µ_t, µ, HVL, N_eff, Z_eff, EBF and EABF are 0.02-7 cm²/g, 0.04-17 cm^-1, 0.045-20 cm, 5-14, 3 × 10²³-8 × 10²³ electron/g, 0-2000, and 0-3500. Shielding performance is BS4, BS3, BS3, BS1 in descending order, but worse than ordinary concrete. µ and HVL of BS1-BS4 for ⁶⁰Co gamma ray is 0.095-0.110 cm^-1 and 6.3-7.2 cm. Shielding mechanism is main interactions for attenuation gamma ray by BS1-BS4 are elements with higher content or higher atomic number via Photoelectric Absorption at low energy range, and elements with higher content via Compton Scattering and Pair Production in Nuclear Field at middle and higher energy range.

• 대한기계학회논문집A
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• 제29권5호
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• pp.689-697
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• 2005

This paper presents the reliability estimation of door hinge for home appliances, which consists of bushing and shaft. The predominant failure mechanism of bushing made of polyoxymethylene(POM) is brittle fracture due to decrease of strength caused by voids existing, and that of shaft made of acrylonitrile-butadiene-styrene(ABS) is creep due to plastic deformation caused by excessive temperature and lowering of glass transition temperature by absorbed moisture. Since the brittle fracture of bushing is overstress failure mechanism, the load-strength interference model is used to estimate the failure rate of it along with failure analysis. By the way, the creep of shaft is wearout failure mechanism, and an accelerated life test is then planned and implemented to estimate its lifetime. Through the technical review about failure mechanism, temperature and humidity are selected as accelerating variables. Assuming Weibull lifetime distribution and Eyring model, the life-stress relationship and acceleration factor, $B_{10}$ life and its lower bound with $90\%$ confidence at worst case use condition are estimated by analyzing the accelerated life test data.