• 대한한방부인과학회지
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• 제21권2호
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• pp.152-165
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• 2008

Purpose: It is the purpose of this study to investigate the anti-inflammatory effects and mechanism of cheukbaekjurpihwan(CBJPH) extract on LPS (lipopolysaccharide)-induced inflammatory mediators in murine peritoneal macrophages. Methods: To evaluate anti-inflammatory effects of CBJPH extract, the production of cytokines(TNF-${\alpha}$(tumor necrosis factor-alpha), IL(interleukin)-6, IL-12) and NO(nitric oxide) was measured in vitro and in vivo. And western blot analysis has been done to look into the mechanism. Results: CBJPH extract reduced LPS-induced NO, TNF-${\alpha}$ and IL-6, IL-12 productions in peritoneal macrophages. CBJPH extract inhibited the activation of JNK(c-Jun N-terminal kinase), but didn't inhibit the activation of MAPKs (mitogen-activated protein kinases) such as p38, ERK1/2(extracelluar signal-regulated kinase1/2) and the degradation of $I_{\kappa}B-{\alpha}$(inhibitory kappa B-alpha) in the LPS-stimulated peritoneal macrophages. CBJPH extract suppressed LPS-induced endotoxin shock and the productions of TNF-${\alpha}$, but not of IL-6, after an oral administration of CBJPH extract Conclusion: CBJPH extract suppressed the productions of LPS-induced NO and cytokines by preventing JNK from phosphorylation, which may provide a clinical basis for anti-inflammatory properties of CBJPH.

• International Journal of Aeronautical and Space Sciences
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• 제16권1호
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• pp.50-63
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• 2015

Explosive bolts are one of pyrotechnic release devices, which are highly reliable and efficient for a built-in release. Among them, ridge-cut explosive bolts which utilize shock wave generated by detonation to separate bolt body produce minimal fragments, little swelling and clean breaks. In this study, separation phenomena of ridge-cut explosive bolts or ridge-cut mechanism are computationally analyzed using Hydrocodes. To analyze separation mechanism of ridge-cut explosive bolts, fluid-structure interactions with complex material modeling are essential. For modeling of high explosives (RDX and PETN), Euler elements with Jones-Wilkins-Lee E.O.S. are utilized. For Lagrange elements of bolt body structures, shock E.O.S., Johnson-Cook strength model, and principal stress failure criteria are used. From the computational analysis of the author's explosive bolt model, computational analysis framework is verified and perfected with tuned failure criteria. Practical design improvements are also suggested based on a parametric study. Some design parameters, such as explosive weights, ridge angle, and ridge position, are chosen that might affect the separation reliability; and analysis is carried out for several designs. The results of this study provide useful information to avoid unnecessary separation experiments related with design parameters.

• 한국신뢰성학회지:신뢰성응용연구
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• 제17권4호
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• pp.355-361
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• 2017

Purpose: The purpose of this research is to establish the life test method for ceramic heater and identify the failure mechanisms. Methods: We do accelerated life test in the condition of thermal shock and failure analysis for failed samples. Conclusion: The main failure mechanisms of ceramic heater are identified as overstress failure mechanisms as results of failure analysis and the shape parameters of weibull distribution by accelerated life test are identified as 0.8, 1.2 and 0.4 each at $400^{\circ}C$, $600^{\circ}C$ and $900^{\circ}C$. At $900^{\circ}C$, the shape parameter 0.4 means that It is exactly initial failure caused that the stress exceeds the strength of ceramic heater highly and the shape parameters 0.8, 1.2 at $400^{\circ}C$, $600^{\circ}C$ means that the shape parameters are around 1.0 so that the main failure mechanism is overstress failure which is same result as failure analysis. It means that the appropriate life test method for ceramic heater is reliability qualification test method rather than accelerated life test.

• 셀메드
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• 제9권3호
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• pp.4.1-4.8
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• 2019

Now researchers have focused attention on exploring the mechanism of acute responses of heat stress given in heat therapy that ultimately promotes the long term health benefits. Heat therapy is not a new idea rather it was practiced since thousands years back in the form of hot bath, sauna bath, steam room. Similarly in Ayurveda there is very comprehensive description of heat therapy in the form of Svedan karma (Sudation therapy). Svedan is a process to induce sweating artificially in a patient who had already undergone Snehan. Svedan is applied for purification of body, as well as in management of various disorders originated due to vitiation of Vata, Kapha Dosha, Meda Dhatu and musculoskeletal disorders. It produces various beneficial effects by augmenting the Agni like clears the channels, liquefies the deposited Dosha, regulates Vata Dosha, helps in removal and pacification of Dosha, augments metabolism (Agni Deepan), increases appetite, flexibility in body parts, softness and shining of skin, removes coldness, stiffness, drowsiness, improves joint motility. However, Svedana karma is vastly used by Ayurveda Physicians in treatment of various disorders but the mechanisms of beneficial effects produced by Svedan Karma are yet not completely explored on scientific basis. In this article, we will discuss and try to establish a possible mechanism of action of Svedana karma in relation to heat stress, mitochondrial adaptation, heat shock protein (HSP) and glucocorticoids as these are secreted under stressful conditions.

• The Journal of Asian Finance, Economics and Business
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• 제9권1호
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• pp.177-187
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• 2022

Theoretical literature agrees on the interaction between financial instability and economic activity but explains it's dynamic in two points of view: one is that the transmission mechanism occurs in one unique regime and the other reckons a shift of regime leads to the alteration of the transmission mechanism. This study aims to find evidence of the multi-regime transmission for ASEAN developing countries. The author employs the technique of Threshold vector auto regression using the financial stress index standing for financial instability. Monthly data is collected, covering a period long enough with many episodes of high stress in recent decades. There are two conclusions: (1) A financial shock has a negative and stronger impact on economic activity during a high-stress period than it does during a low-stress period; (2) the response of economic activity to a negative financial shock during high-stress periods is stronger than it is during normal times. The findings point to the importance of the financial stress index as an additional early warning indicator for the real economy sector, as well as the positive effect that a reduction in financial stress may have on economic activity, implying the importance of "unconventional" monetary policy in times of high financial stress.

• 한국항공우주학회지
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• 제37권5호
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• pp.457-463
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• 2009

본 논문에서는 위성 본체에 장착된 태양 전지 패널을 위성으로부터 분리하기 위한 새로운 개념의 비폭발식 분리 메커니즘을 제안하였으며, 구동기로서 형상기억합금을 이용한 스프링 형상의 구동기를 채택하였다. 먼저 제안된 분리 메커니즘을 구동하기 위해서 필요한 구동력을 측정하였으며, 구동하기에 적절한 구동기를 제작하기 위하여 이론적 계산을 통하여 스프링 형상의 형상기억합금 구동기를 설계/제작 하였다. 최종적으로 분리 메커니즘과 형상기억합금 구동기를 통합하고 분리 장치의 반응속도시험, 사전 하중(Preload) 시험, 충격시험을 통하여 검증하였다. 상기한 소형위성용 비폭발식 저충격 분리장치 개발을 통하여 그동안 사용되었던 선진국의 폭발식 분리장치를 대체할 수 있는 위성 부품의 국산화에 계기를 마련하고자 한다.

• 마이크로전자및패키징학회지
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• 제14권2호
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• pp.35-40
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• 2007

Sn-8Zn-3Bi 무연 솔더 페이스트의 접합부신뢰성 및 적합성을 평가하기 위해 유(SnPb) 무연(Sn, SnBi)도금된 Cu 리드프레임 QFP(Quad Flat Packager)를 사용하여 열충격 조건 하에서의 인장 강도의 변화 및 파괴 기구에 대한 분석을 실시하였다. 리드 도금의 종류에 상관없이 모든 시험 시편에서 열충격 사이클 수의 증가에 비례하여 접합부의 취성 특성이 강화되어 인장 강도가 감소하는 것을 확인하였다. 하지만, 접합부에는 열팽창 계수의 차이에 의해 야기될 수 있는 미세 균열은 발견되지 않았다. 단면 관찰 및 변위 이력 곡선 분석을 통하여 열충격 사이클 수의 증가에 따른 인강 강도의 감소는 접합부의 파괴 기구의 변화에 기인되었음을 확인하였다. 본 실험을 통해 Sn-3Zn-3Bi 솔더의 유 무연 도금 Cu 리드프레임과의 우수한 작업 특성과 열충격 환경 하에서도 우수한 기계적 접합 특성을 유지하는 것을 확인할 수 있었다.

• The Korean Journal of Physiology and Pharmacology
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• 제22권4호
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• pp.457-465
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• 2018

The expression of BCL-2 interacting cell death suppressor (BIS), an anti-stress or anti-apoptotic protein, has been shown to be regulated at the transcriptional level by heat shock factor 1 (HSF1) upon various stresses. Recently, HSF1 was also shown to bind to BIS, but the significance of these protein-protein interactions on HSF1 activity has not been fully defined. In the present study, we observed that complete depletion of BIS using a CRISPR/Cas9 system in A549 non-small cell lung cancer did not affect the induction of heat shock protein (HSP) 70 and HSP27 mRNAs under various stress conditions such as heat shock, proteotoxic stress, and oxidative stress. The lack of a functional association of BIS with HSF1 activity was also demonstrated by transient downregulation of BIS by siRNA in A549 and U87 glioblastoma cells. Endogenous BIS mRNA levels were significantly suppressed in BIS knockout (KO) A549 cells compared to BIS wild type (WT) A549 cells at the constitutive and inducible levels. The promoter activities of BIS and HSP70 as well as the degradation rate of BIS mRNA were not influenced by depletion of BIS. In addition, the expression levels of the mutant BIS construct, in which 14 bp were deleted as in BIS-KO A549 cells, were not different from those of the WT BIS construct, indicating that mRNA stability was not the mechanism for autoregulation of BIS. Our results suggested that BIS was not required for HSF1 activity, but was required for its own expression, which involved an HSF1-independent pathway.

• Archives of Pharmacal Research
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• 제21권1호
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• pp.46-53
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• 1998

When NIH3T3 cells were exposed to mild heat and recovered at $37^{\circ}C$ for various time intervals, they were thermotolerant and resistant to subsequent stresses including heat, oxidative stresses, and antitumor drug methotrexate which are apoptotic inducers. The induction kinetics of apoptosis by stresses were determined by DNA fragmentation and protein synthesis using $[35^S]$methionine pulse labeling. We investigated the hypothesis that thermotolerant cells were resistant to apoptotic cell death compared to control cells when both cells were exposed to various stresses inducing apoptosis. The cellular changes in thermotolerant cells were examined to determine which components are involved in this resistance. At first, the degree of resistance correlates with the extent of heat shock protein synthesis which were varied depending on the heating times at $45^{\circ}C$ and recovery times at $37^{\circ}C$after heat shock. Secondly, membrane permeability change was observed in thermotolerant cells. When cells prelabeled with $[^{3}H]$thymidine were exposed to various amounts of heat and recovered at $37^{\circ}C$ for 1/2 to 24 h, the permeability of cytosolic $[^{3}H]$thymidine in thermotolerant cells was 4 fold higher than that in control cells. Thirdly, the protein synthesis rates in thermotolerant and control cells were measured after exposing the cells to the same extent of stress. It turned out that thermotolerant cells were less damaged to same amount of stress than control cells, although the recovery rates are very similar to each other. These results demonstrate that an increase of heat shock proteins and membrane changes in thermotolerant cells may protect the cells from the stresses and increase the resistance to apoptotic cell death, even though the exact mechanism should be further studied.

• 대한조선학회논문집
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• 제57권1호
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• pp.8-14
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• 2020

The implosion phenomena of pressure vessels operating in deep water under extremely high external pressure have been well known. The drastic energy release to ambient field in the form of pressure pulse is accompanied with catastrophic collapse of shell structure. Such a proximity shock wave could be a serious threat to the structural integrity of adjacent submerged body and several suspected accidents have been reported. In this study, basic research for the occurrence and development of shock wave due to implosion was carried out. The mechanism of pressure pulse generation and energy dissipation were investigated, and a simplified kinematic model to approximate the collapse modes of circular tubes which can be generated by external pressure and implosion was examined. Using the simplified kinematic model, the process of energy dissipation was formulated, and the magnitude of released pressure shock wave was estimated quantitatively. To investigate the validity of developed kinematic model and shock wave estimation process, the results from a nonlinear FE analysis code and collapse test carried out using pressure chamber were compared with the results from the developed kinematic model.