• 대한기계학회논문집A
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• 제28권7호
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• pp.1014-1020
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• 2004

The present work complies the elastic stress concentration factor for a pipe with local wall thinning, based on detailed three-dimensional elastic FE analysis. To cover practically interesting cases, a wide range of pipe and defect geometries are considered, and both internal pressure and global bending are considered. Resulting values of stress concentration factors are tabulated for practical use, and the effect of relevant parameters such as pipe and defect geometries on stress concentration factors are discussed. The present results would provide valuable information to estimate fatigue damage of the pipe with local wall thinning under high cycle fatigue.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.87-94
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• 1999

The structural behavior of welded steel box columns subjected to axial compression and combined load of axial and horizontal load is described. The nonlinear stress-strain relation of the material and residual stress resulted from welds were included in the analysis. Inelastic buckling analysis of hollow rectangular sections of various width-thickness and slenderness ratios was carried out using the semi-analytical and spline finite strip method to investigate the local and global bucking stress and mode interaction. The buckling stress was compared with test results and design curves. Post-buckling behavior was traced by the finite element program(ADINA) and compared with experimental results. The comparison showed that the ultimate stress can be used for the design purpose.

• Structural Engineering and Mechanics
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• 제20권1호
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• pp.123-141
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• 2005

Design details pertaining to the connection between some recently developed fiber reinforced polymer (FRP) composite deck systems and the supporting girders require openings through cells of the deck. This significantly changes the stress distribution in these components. As a result, the conventional assumptions that deck designs are controlled by their stiffness, and not strength, needs a closer examination. This paper proposes an analytical method to investigate the stress states and failure mechanisms using a type of "global-local" modeling perspective, incorporating classical lamination theory and first ply failure criterion with use of appropriate stress concentration factors around the cutouts. The use of a "smeared-stress" approach is presented as a potential means of simplifying certain FRP specific complexities, while still enabling prediction of overall failure.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권1호
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• pp.37-44
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• 2015

본 연구에서는 유한요소해석으로 냉장고 낙하충격에 대한 하힌지의 변형거동을 분석했다. 우선 하힌지 및 하부포장재 동적물성 확보를 위해 각각 속도 별 굽힘시험과 압축시험을 수행했다. 이어 시험에서 얻은 하중-변위곡선과 유사한 거동을 나타내는 하힌지 및 하부 포장재의 유동응력식을 역공학으로 얻었다. 확보한 물성데이터를 이용해 LS-DYNA로 낙하해석을 수행해, 낙하시 냉장고 자체 및 하힌지 변형거동을 분석했다. 최종적으로 3D 측정으로 분석한 실 냉장고 낙하시험으로, 낙하해석 모델의 유효성을 검증했다. 본 연구에서 제시한 해석모델은 추후 하힌지 및 포장재의 내 충격설계 등에 효과적으로 활용될 수 있을 것이다.

• 전산구조공학
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• 제11권1호
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• pp.261-274
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• 1998

본 연구에서는 무요소방법에 적응적 해석기법을 적용하기 위한 부분 및 전체오차의 평가기법을 제안하였다. 본 연구에서 제안한 오차의 평가방법은 무요소방법에서 계산된 응력이 오차가 큰 영역에서 진동한다는 특성을 이용한 것으로 해석결과 얻어진 응력을 낮은 차수의 형상함수로 투사하는 후처리를 함으로써 가상진동모우드를 제거하고 이때 얻어진 투영응력과 원래의 응력을 비교하여 부분오차 및 전체오차를 구할 수 있다. 1차원 및 2차원 예제해석을 통하여 투영응력을 구할 때 가능한 한 작은 영향영역을 사용하는 것이 바람직하다는 것을 보였으며 이는 영향영역의 크기를 과도하게 설정할 경우 투영응력을 과대 평가할 수 있기 때문이다. 본 연구에서 제안한 오차의 평가기법은 다른 무요소 방법에 적용될 수 있다.

• 정신신체의학
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• 제8권2호
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• pp.201-211
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• 2000

연구목적 : 본 연구의 목적은 스트레스인자지각 척도인 Global Assessment of Recent Stress(GARS) Scale의 한국판의 타당도와 신뢰도를 평가하고자 하는데 있다. 방법 : 이 척도에 대한 요인분석은 스트레스인자 8문항에 대한 maximum-likelihood factor analysis후 사각회전(oblique rotation)을 시행하였다. 이 자료들을 요인분석한 결과 1개의 하위요인만이 추출되었다. 상기 척도의 신뢰도는 정상인 69명에게 2주 간격으로 검사-재검사를 시행, 분석한 결과 두 기간간의 8개 스트레스인자 점수의 상관계수가 .85~.95로 모두 유의한 상관성을 보였다. 한편 내적 일치도는 전체적인 스트레스접수를 제외한 7개 문항의 내적 일치도를 산출한 결과 Cronbach's $\alpha$는 .86으로 통계적으로 유의하게 높았다. 공존타당도는 스트레스반응척도, perceived stress questionnaire(PSQ), symptom checklist-9G-R(SCL-9G-R)의 신체화, 불안, 우울, 적대감척도, 전체지표의 총점과 본 척도의 각 8개 문항의 점수 및 척도 전체접수간의 상관성을 각각 비교한 결과 모두 유의하게 높은 것으로 나타났다. 변별타당도는 환자군 242명(불안장애 71명, 우울장애 73명, 신체형장애 47명, 정신신체장애 51명)과 정상군 215명간에 스트레스인자척도 점수를 각각 비교함으로써 이루어졌다. 환자군은 정상군보다 질병 및 상해 영역과 전반적인 스트레스지각점수가 각각 유의하게 더 높았다. 불안장애군이 정상군보다 질병 및 상해 영역의 스트레스지각점수가 유의하게 더 높았고, 우울장애군은 정상군보다 전반적인 스트레스지각점수가 유의하게 더 높았다. 한편 우울장애군은 정신신체장애군보다 대인관계 영역의 스트레스지각점수와 전반적인 스트레스지각점수가 각각 유의하게 더 높았다. 결론 : 이상의 결과들은 전반적인 스트레스평가 척도가 신뢰도 및 타당도가 모두 유의한 수준으로 스트레스에 관련된 분야의 연구에 효과적으로 이용될 수 있는 도구임을 시사해 준다. 또한 우울장애군이 정신신체장애군에 비해 스트레스인자에 대한 지각이 더 높음을 시사해 준다.

• Interaction and multiscale mechanics
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• 제3권3호
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• pp.213-234
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• 2010

A multiscale method is presented for analysis of thin slab structures in which the microstructures can not be reduced to two-dimensional plane stress models and thus three dimensional treatment of microstructures is necessary. This method is based on the classical asymptotic expansion multiscale approach but with consideration of the special geometric characteristics of the slab structures. This is achieved via a special form of multiscale asymptotic expansion of displacement field. The expanded three dimensional displacement field only exhibits in-plane periodicity and the thickness dimension is in the global scale. Consequently by employing the multiscale asymptotic expansion approach the global macroscopic structural problem and the local microscopic unit cell problem are rationally set up. It is noted that the unit cell is subjected to the in-plane periodic boundary conditions as well as the traction free conditions on the out of plane surfaces of the unit cell. The variational formulation and finite element implementation of the unit cell problem are discussed in details. Thereafter the in-plane material response is systematically characterized via homogenization analysis of the proposed special unit cell problem for different microstructures and the reasoning of the present method is justified. Moreover the present multiscale analysis procedure is illustrated through a plane stress beam example.

• Steel and Composite Structures
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• 제18권6호
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• pp.1353-1368
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• 2015

A finite element model is presented for the analysis of composite steel-concrete beams based on a refined high-order theory. The employed theory satisfies all the kinematic and stress continuity conditions at the layer interfaces and considers effects of the transverse normal stress and transverse flexibility. The global displacement components, described by polynomial or combinations of polynomial and exponential expressions, are superposed on local ones chosen based on the layerwise or discrete-layer concepts. The present finite model does not need the incorporating any shear correction factor. Moreover, in the present $C^1$-continuous finite element model, the number of unknowns is independent of the number of layers. The proposed finite element model is validated by comparing the present results with those obtained from the three-dimensional (3D) finite element analysis. In addition to correctly predicting the distribution of all stress components of the composite steel-concrete beams, the proposed finite element model is computationally economic.

• 성인간호학회지
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• 제22권2호
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• pp.182-189
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• 2010

Purpose: The purpose of this study was to identify predictors on drinking problems of university students. Methods: The participants were 359 students by convenience sampling in P city. Data were collected from October 15 to December 20, 2007 using drinking problems questionnaire, Global assessment of recent stress scale, CES-D and self-esteem scale. The collected data were analyzed by descriptive statistics, Pearson's correlation coefficient, and stepwise multiple regression. Results: There were positive correlations between stress and drinking problems, between depression and drinking problems. Also, there were negative correlations between stress and self-esteem, between depression and self-esteem. In stepwise multiple regression analysis, the most powerful predictor of drinking problems was depression. Conclusion: The results suggest that effective management of depression and stress can be considered when developing a prevention program of drinking problems for university students.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 추계학술대회
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• pp.483-493
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• 2009

The global economic recession caused a great change of the labor environment such as restructurings and unstable employment. This facts brought about an increase in sense of rivalry, over workload, job uncertainty and lowering of self-confidence. Due to the fact that the work process and employing system in construction field is little differ from normal industries, especially, labors working in construction field are much exposed to the job stress. On this study, we survey construction-field labors and made an analysis of the gathered data through the statistic method to reveal what kind of job-stress factors influence on the defects of construction works. As the result, we investigated the truth of the induction factors which cause the job-stress in costruction field and proposed an alternative plan for an effective job-stress management which make the defect rate low.