• 소성∙가공
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• 제21권5호
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• pp.291-297
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• 2012

In this paper, the effect of back tension in multi-pass drawing or wiredrawing on the central bursting defect is investigated using finite element predictions. A rigid-plastic finite element method was used together with the McClintock damage model. Central bursting defects under different back tension stress values ranging from 0% to 20% of the yield strength of the material were predicted and they were compared to understand the effect of the back tension stress values on the central bursting defect. It is found that the level of back tension has a strong influence on the cumulative damage. Thus, higher back tension raises the possibility of the central bursting defect occurring, even though it decreases the interfacial pressure between the die and the work piece.

• 한국생산제조학회지
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• 제21권6호
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• pp.885-891
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• 2012

In this study, some structural analysis using 3D CAD data, material properties, load conditions and boundary conditions are carried out to evaluate structural stability of the multi-aerial platform for high-rise fire fighting and rescue. We conduct structural analysis for the upper structures such as turn table, booms and basket, by using a universal structural analysis program NASTRAN. As the results, there is local stress exceeding the yield strength, but it is able to relax stress concentration in a way such as changing thickness of the structure or making larger inertia moment in cross section of booms.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1065-1066
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• 2006

The multi-resonant converter minimizes the parasitic oscillations using the resonant tank circuit absorbed parasitic reactances in a converter. So the converter can be operated at a high frequency and it provides a high efficiency because the switching power losses are reduced effectively. However, the high resonant voltage stress of semiconductors leads to the conduction loss. In this paper, it is proposed the novel flyback multi-resonant converter. The converter input is divided by two series input capacitors. And also the resonant stress is reduced to 2-3 times input voltage without any complexity and it provides the various circuit schemes in lots of applications. The proposed converters are verified through simulation and experiment.

• 대한기계학회논문집
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• 제12권6호
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• pp.1246-1251
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• 1988

본 연구에서는 균열 첨단의 극좌표를 직각좌표(x, y)로 변환시킨 후 슬랩상사 이론을 적용시켜 균열첨단 부근에서 많은 데이터의 측정이 가능한 새로운 해석법인 다 점 선정법(multi-point selection method)을 개발하였다.또 이 해석법으로 유한판 중앙 직선균열의 응력확대계수를 해석하여 종래 해석법의 결과와 비교 검토하여 그 유 용성을 확인하였다.

• 한국실내디자인학회논문집
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• 제36호
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• pp.76-83
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• 2003

The purpose of this study is to know how to improve environment of multi-bed room by investigating and analysing factors influencing to patients. 1 measured stress and satisfaction degrees about patient room for 4ㆍ5ㆍ6ㆍ7 men of domestic general hospital wards. The results of research show that patients of 4 bed room appeared the fewest stress and highest satisfaction degree among patients of other room styles. The patients positioned between two beds can give us more stress and fewer satisfaction than others. These results have proven that 4 bed room patients are offering comfortable environment than any other room types as a healing environment. When patient room area are more than 7.3$M^2$ per 1 person, bed interval space is more than 120cm, there is curtain between bed, transit space such as a toilet were established in patient room, patients' satisfaction appeared high.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.378-383
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• 2008

Bogie frame of the locomotive is an important structural member for the support of vehicle loading. A lot of study has been carried out for the prediction of the structural integrity of the bogie frame in experimental and theoretical domains. The objective of this paper is to estimate the structural integrity of the bogie frame. Strength analysis has been performed by finite element analysis. From these analysis, stress concentration areas were investigated. For evaluation of the loading conditions, dynamic stress were measured by using strain gage. It has been found that the stress and strain due to the applied loads were multi-axial condition according to the location of strain gage. The fatigue strength evaluations of the bogie frame are performed to investigate the effect of the multi-axial load through the employment of the critical plane approach.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2042-2044
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• 1998

In this paper, we proposed the alternated forward multi-resonant converter. It can reduce the voltage stress due to the operation of two multi resonant switches and also provides a high frequency applications. The proposed circuit is verified through the PSpice simulation and the 50W experimental set with 2MHz maximum frequency. The measured voltage stress is up to 170V of 2.9 times the input voltage and the efficiency is about 81.66% at low line.

• Journal of Welding and Joining
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• 제29권4호
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• pp.61-66
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• 2011

The purpose of this study is to develop improved boom structures with reliable fatigue strength of weldment and lower production cost. For that purpose, multi-body dynamic analysis was performed to evaluate forces acting on arm & boom cylinders and joints of boom structure during operation of an excavator for three working postures, then stress analysis was made to investigate stress distribution around diaphragms at the bottom plate of boom structures which was known to be susceptible to fatigue failures of welded joints, and finally boom structures with optimum arrangement of diaphragms was proposed. This work mainly consists of the following two parts: part 1 focuses on multi-body dynamic analysis of excavators during operation and part 2 includes evaluations of fatigue strength of welded joints for modified boom structures.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.86-89
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• 2004

Recently polymer arresters are being used widely but we don't have appropriate long term characteristics test methods. Therefore we need to develop special test facility to evaluate long term reliability of polymer arresters. It's polymeric housing can be degraded by environmental stress and the interface between housing and inner module can be affected by moisture absorption. This moisture absorption can cause leakage current and tracking in the interface. We developed multi stress accelerated ageing test facility to simulate field conditions including UV, temperature, humidity, voltage, salt fog and rain. In addition, we carried out field exposure test at the outdoor test yard and characteristics analysis of field operated specimens to evaluate accelerating factor of this accelerated aging test.

• 동력기계공학회지
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• 제18권4호
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• pp.85-90
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• 2014

In this paper, the transient thermal and residual stress analysis of the welding of 9% Ni steel plates using the FEA software ABAQUS are presented. The 9% Ni steel plates are welded manually with welding consumables of 70% Ni based Inconel type super-alloys (YAWATA WELD B (M)), producing a multi-pass/multi-layer butt weld. For these materials, temperature dependant mechanical and thermal material properties are used in the analysis. The back gouging is considered in welding process simulation. The FE thermal results are validated by comparing the real fusion profile and heat affected zone (HAZ). In addition, the continuous indentation test was conducted to measure the strength of base metal, HAZ and weld metal.