• 한국유체기계학회 논문집
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• 제14권5호
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• pp.63-68
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• 2011

This paper presents an optimization procedure for performance improvement of a tunnel ventilation jet fan. Optimization techniques based on response surface approximation (RSA) are employed to improve the aerodynamic performance of a tunnel ventilation jet fan. For numerical analysis, three-dimensional Renolds- averaged Navier-Stokes (RANS) equations with shear stress transport turbulence model are discretized by using finite volume approximations and solved on hexahedral grids to evaluate the total efficiency at the operating condition as the objective function. Four geometric variables defining the meridional length and the thickness profile at the hub and shroud in the jet fan rotor are selected as design variables for the numerical optimization. The results of the numerical optimization show that the total efficiency of the optimized model is significantly improved in comparison with the base model.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1705-1712
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• 2001

Mechanical component has striation with constant width and SEM can estimate fracture type and loading condition. SEM has benefit to fatigue fracture analysis but striation can be observed according to the kind of material and range of crack growth rate and can't. In this case, it needs AFM that can measure 3-dimensional surface profile with resolution of atomic size. In this study. to find fracture reason of torsion-mounted blade in nuclear plant, we estimate the relation between stress intensity factor range and root mean square roughness in 12% Cr steel by AFM and predict in-service loading condition of turbine blade. failure analysis is performed by finite element method and Goodman diagram on torsion-mounted blade.

• Molecular & Cellular Toxicology
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• 제5권4호
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• pp.283-290
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• 2009

Differential gene expression profiling was performed in the hepatic tissue of marine medaka fish (Oryzias javanicus) after exposure to benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon (PAH), by heterologous hybridization using a medaka cDNA microarray. Thirty-eight differentially expressed candidate genes, of which 23 were induced and 15 repressed (P<0.01), were identified and found to be associated with cell cycle, development, endocrine/reproduction, immune, metabolism, nucleic acid/protein binding, signal transduction, or non-categorized. The presumptive physiological changes induced by BaP exposure were identified after considering the biological function of each gene candidate. The results obtained in this study will allow future studies to assess the molecular mechanisms of BaP toxicity and the development of a systems biology approach to the stress biology of organic chemicals.

• 대한화학회지
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• 제51권1호
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• pp.51-55
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• 2007

화탄과정의 폐수에서 단리된 티오시안산염 이용 균주인 Bacillus brevis의 지방산 조성을 기체크로마토그라피로 분석하였다. 이 균주는 포화 및 불포화 지방산이외에 히드록시 지방산을 포함하고 있다. 히드록시 지방산은 일반적으로 흥미로운 박테리아의 화학적 계통분리학의 지표로 알려져 있다. 이 균주에는 시클로프로판 지방산이 전혀 없다. 이균주와 Baciluus brevi B-33 및 B-34 균주의 지방산 조성을 비교하였을 때 이 균주들 사이에 차이가 있었다. 이러한 차이는 티오시안산염의 충격 효과 때문일 것으로 보인다. 이 결과는 지방산의 생합성이 환경에 크게 의존된다는 것을 지지하여 준다.

• 품질경영학회지
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• 제40권3호
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• pp.286-294
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• 2012

Purpose: In this study, we propose the ESS process model which, in order to improve reliability of electronic equipment, can be referenced in both development and production phases. Methods: ESS guidelines such as MIL handbooks or private sector ESS guidelines are used for devising the proposed ESS model. Especially, proposed model is customized by using those references in order to be optimized in the domestic development and production phases. Results: ESS-related-requirements which is specified in the Technical Data Package(TDP) for the area of guided missile systems are analyzed. Current status of the requirement and screening strength are analyzed for those systems to show what kind of weak points should be improved. Conclusion: A ESS guideline which is applicable to the domestic weapon acquisition environment is proposed. As such, the necessity and detail guidelines of the proposed model are explained.

• 한국소음진동공학회논문집
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• 제11권4호
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• pp.13-21
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• 2001

Electrorheological(ER) fluid is a kind of smart material with variable shear stress and dynamic viscosity under various electric field intensity. Electric field can control the damping characteristics of ER damper. The objective of this study is the analysis of the performance of ER damper and its application to shock absorber. Idealized nonlinear Bingham plastic shear flow model is used to predict the velocity profile between electrodes. Cylindrical dashpot ER damper with moving electrode is constructed and tested under various electric fields. The analytic and experimental results for damping force are compared and discussed. Drop test system using ER damper is prepared to identify transient vibration characteristics. The rebound is eased as the applied electric field increases. When semi-active control algorithm is applied, rebound phenomenon disappears and vibration energy level decays faster than the case of zero electric field.

• 한국가시화정보학회지
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• 제12권2호
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• pp.23-29
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• 2014

Although many studies have been done on an open-end capillary, the invasion into a closed end capillary is still novel in its investigation. In this research we have explored the fluid invasion in closed-end capillaries where the shape of the meniscus and the height of invasion were accompanied by gas compression inside the capillary. Theoretically, the one dimensional momentum balance equation shows the fluid oscillation. In the experiments, we have found the different phenomena, either the fluid oscillation with low frequency or no oscillation. This discrepancy is mostly caused by two factors. First, a continuous decrease of the advancing contact angle due to decreasing invasion velocity as increasing pressure inside the closed-end capillary reduces the invasion velocities. Second, the high shear stress within the entrance length region was generated by the plug like velocity profile.

• 기본간호학회지
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• 제17권4호
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• pp.487-497
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• 2010

Purpose: This study examined the validity and reliability to develop a lifestyle evaluation tool for metabolic syndrome patients. Methods: A methodological research design was used. The construct factors and preliminary items were identified by reviewing previous researches and tools related to lifestyle and reviewed by ten experts. It was tested with 195 patients with metabolic syndrome in a university hospital. The data were analyzed with SPSS/WIN 14.0. Results: To test the validity, principal component analyses were used and resulted in the extraction of six components. The convergent validity resulted r= .72 (p<.001) with Health Promotion Lifestyle Profile. The discriminant validity with Center for Epidemiologic Studies Depression Scale resulted r= -.15 (p=.004). The Internal consistency of the tool had an Cronbach's a of .92. The self-report format Lifestyle Evaluation Tool for the patients with metabolic syndrome was developed with 36 items and four-rating scales:'physical activity and weight control' eight items, 'dietary habits' sixteen items, 'drinking and smoking' three items, 'sleep and rest' two items, 'stress' three items, 'drug and health management' four items. Conclusion: This Tool will evaluate health behaviors in patients with metabolic syndrome. Also, it will contribute to the development of nursing intervention to improve the metabolic syndrome patients' lifestyle.

• 여성건강간호학회지
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• 제17권4호
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• pp.337-345
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• 2011

Purpose: The purpose of this study is to examine the impact of type D personality on health status and health promoting behaviors in middle-aged women. Methods: A cross-sectional study design was used with 220 middle aged women. All participants completed 3 measuring tools: a 14-item Type D Personality Scale, a 12-item Short Form Health Survey Questionnaire version 2, and Health Promoting Lifestyle Profile-version II. All were completed in November 2010. Results: The prevalence of type D personality was 34.5%. Type D women had significantly lower physical (p=.020) and mental health status (p<.001) compared with non-type D women. In addition Type D women reported significantly poorer performance of health responsibility (p=.015), physical activity (p=.001), nutrition (p=.027), spiritual growth (p<.001), interpersonal relations (p<.001) and stress management (p<.001) techniques in health behaviors than non-type D women. Conclusion: Type D personality is a vulnerability factor that affects health status and is associated with poor health promoting behaviors in middle aged women. Therefore, screening for Type D personality is important to detect women at risk for health status and quality of life in community settings in Korea.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2387-2396
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• 2000

Wear and operation characteristics of Nylon and Acetal pinion against steel gear were studied to gain a better understanding of their tribological and mechanical behavior. Tests were conducted with power circulating gear test rig under unlubricated conditions. Specific wear rates were measured as a function of applied load and total revolution. The worn tooth surfaces were examined with a profile projector and camera. Nylon pinion showed lower specific wear rates than Acetal pinion, but it revealed breakage at high load. Principal wear depths were developed at tooth tip and below the pitch line of pinion. Life estimation for the Nylon pinion was made by taking into account steel gear equivalent Hertz stress and average sliding velocity. The dominant wear mechanisms were adhesion and abrasion.