• Journal of Mechanical Science and Technology
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• 제19권5호
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• pp.1065-1071
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• 2005

In this study, residual stress distribution in multi-stacked film by MEMS (Micro-Electro Mechanical System) process is predicted using Finite Element method (FEM). We evelop a finite element program for residual stress analysis (RESA) in multi-stacked film. The RESA predicts the distribution of residual stress field in multi-stacked film. Curvatures of multi­stacked film and single layers which consist of the multi-stacked film are used as the input to the RESA. To measure those curvatures is easier than to measure a distribution of residual stress. To verify the RESA, mean stresses and stress gradients of single and multi layers are measured. The mean stresses are calculated from curvatures of deposited wafer by using Stoney's equation. The stress gradients are calculated from the vertical deflection at the end of cantilever beam. To measure the mean stress of each layer in multi-stacked film, we measure the curvature of wafer with the left film after etching layer by layer in multi-stacked film.

• 가정간호학회지
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• 제23권2호
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• pp.206-215
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• 2016

Purpose: The purpose of this study was to investigate the level of cultural competence, intercultural communicative competence, and multi-cultural job stress among healthcare workers and to explore factors that are related to their cultural competence. Methods: The study subjects were 142 healthcare workers at a general hospital. Data were collected using a questionnaire on cultural competence, intercultural communicative competence, and multi-cultural job stress. A t-test, ANOVA Pearson's correlation coefficient, and multiple regression analysis were conducted using SPSS. Results: Cultural competence was significantly related to the necessity of multi-cultural education, and intercultural communicative competence was significantly related to age, a vocational career, communication in foreign languages, and having multi-cultural neighbors. Moreover, multi-cultural job stress was significantly related to religion. In multiple regression results, cultural competence was found to be related to intercultural communicative competence and multi-cultural job stress. Conclusion: Healthcare workers who are set to care for multi-cultural patients should improve intercultural communicative competence and reduce multi-cultural job stress.

• 전기학회논문지
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• 제59권6호
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• pp.1131-1135
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• 2010

The development of modern civilization result from the abundance of material. Yet modern people live with chronic mild stress. Excessive chronic mild stress leads to various diseases. From the risk of the disease in order to protect our bodies need to manage chronic mild stress. The purpose of this study is to inspection the effectiveness of detecting in chronic mild stress using the Multi-sensor system. The Multi-sensor system is designed that can be measure three kinds of vital signals of chronic mild stress for the detection. First Photoplethysmogram(PPG), second Electro Dermal Activity(EDA), third Skin Temperature(SKT). The ages and occupations exposed to chronic mild stress, people often use out of this system was applied to dairy products(Pen). In addition, vital signals that occur when the variety of noise was used to remove the accelerometer. Chronic mild stress by the analysis of measured vital signals from Multi-sensor system to the measurement information to a PC to a wireless transmission(Bluetooth). In this study, using Multi-sensor system writing conditions and a variety of situations in the movement to measure vital signals and measurement results verified the accuracy and reliability. Through this measure chronic mild stress in everyday life and managing to maintain will help more healthy lifestyle.

• 한국세라믹학회지
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• 제33권2호
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• pp.127-134
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• 1996

The thermal residual stresses were estimated for brazed Si3N4/S.S.316 joints with Cu/Mo multi-interlayers using FEM, and their bending strengths at room temperature were measured for various interlayer configura-tions. The Cu, Mo multi-interlayer decreased the maximum residual stress in Si3N4 and caused the residual stress redistribution rsulting in the high residual stress at Mo interlayer. The stress distribution in the joints as well as the maximum residual stress in silicon nitride were found to be main factors for determining bending strengths and Weibull modulous of the joints. The bending strength of the brazed Si3N4/S.S.316 joints with specific Cu, Mo multi-interlayer system were found to be above 400 MPa.

• 소성∙가공
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• 제26권3호
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• pp.162-167
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• 2017

The tensile surface residual stress in the multi-pass drawn wire deteriorates the mechanical properties of the wire. Therefore, the evaluation of the residual stress is very important. Especially, the axial residual stress on the wire surface is the highest. Therefore, the objective of this study was to propose an axial surface residual stress prediction model of the multi-pass drawn steel wire. In order to achieve this objective, an elastoplastic finite element (FE) analysis was carried out to investigate the effect of semi-die angle and reduction ratio of the axial surface residual stress. By using the results of the FE analysis, a surface residual stress prediction model was proposed. In order to verify the effectiveness of the prediction model, the predicted residual stress was compared to that of a wire drawing experiment.

• International Journal of Reliability and Applications
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• 제15권1호
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• pp.23-50
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• 2014

This paper deals with formulation of optimum multi-objective modified step-stress accelerated life test (ALT) plan for Burr type-XII distribution under type-I censoring. Since it is impractical to estimate only one objective parameter after conducting costly ALT tests; also, it is not desirable to assume instantaneous changes in stress levels because of limited capacity of test equipments and the presence of undesirable failure modes, therefore, an optimum multi-objective modified step-stress ALT plan has been designed. The optimal test plan consists in determining the optimum low stress level and optimal time at which stress starts linearly increasing from low stress by minimizing the weighted sum of the asymptotic variances of the maximum likelihood estimator of quantile lifetimes at design constant stress. The method developed has been illustrated using an example. Sensitivity analysis has been carried out. Comparative study has also been done to highlight the merits of the proposed model.

• 가정간호학회지
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• 제24권2호
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• pp.133-141
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• 2017

Purpose: This descriptive study aims to analyze the effects of the satisfaction level in the relationship between mother-in-law and daughter-in-law, conflicts between them, acculturative stress and stress coping strategies on elderly depression in multi-cultural families. Methods: The survey was conducted on 89 mothers-in-law, aged 65 or older, in multi-cultural families with a foreign daughter-in-law. Data were collected through structured questionnaires, and then were used to conduct t-test, ANOVA, correlation and multiple regression analyses using the statistical program SPSS 21.0. Results: This study found several factors contributing to depression of mothers-in-law in multi-cultural families. Those factors include living alone without a spouse, poor health, a high level of perceived discrimination and a passive reaction in terms of stress coping strategies. Conclusion: A sense of discrimination perceived by the mothers-in-law having a foreign daughter-in-law implies that the people around them and the community should make efforts to reject distorted perspectives and remove prejudice against foreign daughters-in-law. In addition, the mothers-in-law should receive education and training to use more active and positive stress coping strategies in a stressful situation with the foreign daughter-in-law.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2211-2218
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• 2002

In this study, an optimal design study has been made to determine dimensions of die and multi stress rings for extrusion process. For this purpose, a thermo-rigid-viscoplastic finite element program, CAMPform, was used fur forming analysis of extrusion process and a developed elastic finite element program fur elastic stress analysis of the die set including stress rings. And an optimization program, DOT, was employed for the optimization analysis. From this investigation, it was found out that the amount of shrink fitting incurred by the order of assembly of the die set should be taken into account for optimization when the multi stress rings are used in practice. In addition, it is construed that the proposed design method can be beneficial fur improving the tool life of cold extrusion die set.

• 한국가스학회지
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• 제16권5호
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• pp.52-57
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• 2012

본 연구에서는 유한요소해석법을 사용하여 다접오링의 밀봉특성에 관련된 변형률, 응력, 접촉법선응력을 해석하였다. 밀봉특성에 관한 FEM 해석결과에 의하면, 다접오링에 작용하는 최대 변형률, 최대압축응력, 최대접촉 법선응력은 기존의 오링에 비해 약 1.7배나 더 높게 나타났다. 이것은 다접오링의 절단면에 U홈을 형성하였기 때문이고, 다접오링은 고압가스 용기, 밸브, 가스기기의 밀봉을 유지하는데 매우 유용할 것으로 판단된다. 그리고, 다접오링에서 가스압력을 높여도 압출파손 현상이 발생되지 않았는데, 이것은 U홈이 있기 때문인 것으로 판단된다. 따라서, 다접오링은 기존의 오링에 비해 밀봉수명을 길게 연장시킬 수 있다.

• 한국정밀공학회지
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• 제27권8호
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• pp.70-75
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• 2010

The aim of this study is to evaluate the axial residual stress in multi-pass drawn high carbon steel wire by using FE analysis and XRD. When FE analysis is applied to evaluate the residual stress in drawn wire of multi-pass drawing process, obtaining the reliable effective stress-strain curve at high strain is very important. In this study, a model, which can express the reliable effective stress-strain curve at high strain, is introduced based on the Bridgman correction and tensile test for multi-pass drawn high carbon steel wires. By using the introduced model, FE analysis was carried out to evaluate the axial residual stress in the drawn wires. Finally, the effectiveness of the FE analysis with the introduced stress-strain relation was verified by the measurement of residual stress in the drawn wires through XRD. As a result, the evaluated residual stress of FE analysis shows good agreement with the measured residual stress.