• 한국산학기술학회논문지
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• 제15권4호
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• pp.2399-2405
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• 2014

조립식지그재그 형태의 단일거더시스템이 적용되는 경골형 교량은 비틀림에 취약한 구조이다. 특히 거더와 PHC(Pretensioned spun High strength Concrete) 말뚝의 고정 연결부는 비틀림 하중에 의한 과도한 응력이 집중되는 취약부이므로 이를 저감시키기 위한 방안이 요구된다. 본 연구에서는 연결부에 발생하는 과도한 응력을 저감시키기 위한 다양한 보강재 형식의 효율성을 수치해석적으로 평가하였다.

• 대한기계학회논문집A
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• 제22권2호
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• pp.278-288
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• 1998

An efficient and useful method to improve the local stress field in a displacement-formulated finite element solution has been proposed using the theory of conjugate approximations for a stress field and the Loubignac's iterative method for a displacement field. Validity of the proposed method has been tested through three test examples, to improve the stress field and displacement field in the whole domain and the local regions. As a result of analysis on the test examples, it is found that the stress field in the local regions are approximated to those in the whole domain within a few iterations which have satisfied the original finite element equilibrium equation. In addition, it is found that the local stress field are by far better approximated to the exact stress field than the displacement-based stress field with the reduction of the finite-element mesh-size.

• 여성건강간호학회지
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• 제9권1호
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• pp.70-79
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• 2003

The purpose of this study was to investigate the effects of Aromatherapy, inhalhtion method using Clarysage essential oil on stress in middle-age women. The study design was a one-group pretest-posttest design. The subject were 44 middle-age women with stress in inhalation method of Clarysage essential oil was 2 drops of oil on tissue at 10, 14, 18, before bed for 2 weeks. The study was carried out from August 1 to September 20, 2002. The scale used in the study was the stress scale of Park, Sun Young(1999). The study data was analyzed by frepuency, percent age and t-test using SPSS Win 10.0 program. Result were as follows : 1. The score of physical stress scale was significantly decresed after use of inhalation of Clarysage essential oil. 2. The score of psychological stress scale was significantly decresed after use of inhalation of Clarysage essential oil. In conclusion, the results of this study suggest that inlalation method using Clarysage essential oil is positively supported in stress reduction in middle-aged women.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1315-1323
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• 2014

Although the power density in Double Stator Switched Reluctance Motor (DSSRM) has been improved, the torque ripple is still very high. So, it is important to reduce the torque ripple for specific applications such as Electric Vehicles (EVs). In This paper, an effective rotor shaping optimization technique for torque ripple reduction of DSSRM is presented. This method leads to the lower torque pulsation without significant reduction in the average torque. The method is based on shape optimization of the rotor using Finite Element Method and Taguchi's optimization method for rotor reshaping for redistribution of the flux so that the phase inductance profile has smoother variation as the rotor poles move into alignment with excited stator poles. To check on new design robustness, mechanical analysis was used to evaluate structural conformity against local electromagnetic forces which cause vibration and deformation. The results show that this shape optimization technique has profound effect on the torque ripple reduction.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.263-266
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• 1997

Three dimensional numerical model based on the finite element method(FEM) were developed to predict the mechanical behavior of hip implants. The purpose of this study is to investigate the stress distribution of two types of cementless total hip replacement femoral component -a straight stem and a curved stem, and to compare their effect on the stress shielding between two types by three dimensional finite element method. The authors analyzed von Mises stress in the cortex & stem and compared the stress between the straight and the curved stem. In comparison of stresses between two different design of femoral stem, there was 25% more decrease of stress in straight stem than curved stem in the medial cortex at proximal region. The straight stem had consistently much lower stresses than the curved stem throughout the whole medial cortex with maximum 70% reduction of stress. However, there was little change in stress between nature and 2 implanted femur throughout the lateral cortex. Stress of femoral stem was much higher in the straight stem than the curved stem up to 60%. The straight stem had more chance of stress shielding and a risk of fatigue fracture of the stem compared with the curved stem in noncement hip arthroplasty. In design of femoral stem still we have to consider to develop design to distribute more even stress on the proximal medial cortex.

• 한국해양공학회지
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• 제18권1호
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• pp.22-27
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• 2004

An orthotropic steel deck system is widely adapted form for a long-span bridge. It has many advantages, such as the big reduction of dead weight, the simplicity for erection, and the reduction of the construction period. However, an orthotropic steel deck system requires a lot of welding work, which may result in defects and deformation of connection. Therefore, the research for the general behavior and fatigue strength of the several details in orthotropic steel deck bridge is necessary. The fatigue failure with distortion results from secondary stress by out-of-plane deformation; these kinds of cracks are very difficult to measure, and can not be precisely calculated through finite element analysis. This stress concentration phenomenon generates the fatigue failure around the lower scallop of the transverse rib. This paper presents improved details of the intersection between the longitudinal rib and the transverse rib of an orthotropic steel deck bridge by the third dimensional hit size test, and the finite element method, which can minimize local stress through parametric study.

• 한국안전학회지
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• 제8권1호
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• pp.71-79
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• 1993

The welding implementation used widely in the industrial field is gradually increasing due to weight reduction. unlimited material thickness. simplified structure design. and 1 manufacturing time and cost reduction. The most significant factor that influences the fatigue crack growth rate is the residual stress generated during the welding process. Many researchers have studied the effect of the residual stress on crack growth behavior. Through a fatigue test in a various-thickness welded specimen. redistributed residual stress is measured as the crack is developed. Then. by superposing the measured residual stress on the K value obtained by the finite element method.

• 대한조선학회논문집
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• 제44권5호
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• pp.496-503
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• 2007

Although weld-induced deformation is inevitable in shipbuilding, it is important to reduce it as low as possible during fabrication for a more efficient production of ships' blocks. The weld-induced deformation is more serious in thin plates than in thick plates because heat affect zone of thin plates is wider than that of thick plates, and in addition internal and external constraints much more influence upon weld-induced deformation of thin plates. This paper deals with the application of the mechanical tensioning method to butt weld of thin plates to reduce the transverse and longitudinal deformation. in order to investigate the quantitative effect of tensioning method upon the reduction of angular deformation and shrinkage in longitudinal and transverse direction of weld line, butt welding test have been carried out for several thin plate specimens with varying plate thickness and magnitude of tensile load. Numerical simulation has been also carried out to compare the weld-induced deformation and residual stress. From the present study, it has been found that the tensioning method is very effective on reduction of weld-induced residual stress as well as weld-induced deformation.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.1212-1221
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• 1993

The shape optimization procedure applying finite element method was carried out for the specific purpose of analysis of a tractor chassis frame. Minimization of the mass as an objective function is executed under multiple constrained conditions of nodal displacements and stresses. The optimization process executions were succeeded in converging into single optimum solution. Although mass reduction and stress alleviation were attained by 40% and 26 to 24% respectively , the geometry of the shape is so complicated for fabrication that the refinement of the geometry is of necessity.

• 한국생산제조학회지
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• 제8권1호
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• pp.35-44
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• 1999

In a view point of earth environmental protection and social requirement, adhesively bonded structures of aluminum alloys have become to be employed for the purpose of decreasing fuel ratio by weight reduction and to improve performance in various engineering fields such as aircrafts, automobiles, rolling stocks and so on. In spite of such wide applications in adhesively bonded structures of aluminum alloys, the quantitative fracture criterion and evolution method of its bonded strength have not been established yet. The objective of this paper is to establish fracture criterion considering stress singularity at interface edges in adhesively bonded structures of aluminum alloys. Through the analyses of boundary element method and static fracture experiments with three different types of specimens in the adhesively bonded joints of aluminum alloys, its fracture criterion was proposed and discussed about strength evolution of adhesively bonded structures.