• 대한기계학회논문집A
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• 제26권11호
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• pp.2297-2304
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• 2002

Two-dimensional and three-dimensional finite element methods have been used to analyze the deformation behavior of a shadow mask due to thermal and tension load. The shadow mask inside the Braun tube of a TV set has numerous slits through which the electron beams are guided to land on the designed phosphor of red, green or blue. Its thermal deformation therefore causes landing shift of the electron beam and results in decolorization of a screen. For the realistic finite element analysis, the effective thermal conductivity and the effective elastic modulus arc calculated, and then the shadow mask is modeled as shell without slits. Next a transient thermal analysis of the shadow mask is performed, wherein thermal radiation is a major heat transfer mechanism. Analysis of the resulting thermal deformation is followed, from which the landing shift of the electron beam is obtained. The present finite element scheme may be efficiently used to reduce thermal deformation of a shadow mask and in developing prototypes of a large screen flat TV.

• 마이크로전자및패키징학회지
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• 제26권4호
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• pp.23-31
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• 2019

본 논문에서는 다구찌법과 유한요소법의 수치해석을 통해 인쇄회로기판의 열변형과 열변형에 미치는 설계인자의 영향도를 계산하였다. 인쇄회로기판의 패널과 스트립 레벨은 큐어링 온도조건에서, 유닛 레벨은 리플로우 온도조건에서 수치해석을 수행하였다. 해석결과에 따르면 패널의 열변형이 스트립과 유닛의 열변형량과 형상에 가장 큰 영향을 미치며, 특히 z방향 변형량이 xy평면 방향의 변형량보다 크게 발생하였다. 열변형에 대한 설계인자의 영향도 분석 결과에 의하면 열변형을 줄이기 위한 설계인자들의 영향도와 설계조건이 패널, 스트립과 유닛 레벨에 따라 달라지기 때문에 반도체 패키지의 신뢰성 향상을 목적으로 유닛 레벨의 열변형을 제어하기 위해서는 패널 레벨의 열변형을 제어할 필요가 있고 인쇄회로기판의 층별 두께는 설계인자 수준의 중간으로 선정하는 것이 필요하다.

• 한국주조공학회지
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• 제25권5호
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• pp.209-215
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• 2005

The design of the Metal mold casting should consider several variables such as the material properties and shape of the mold. In particular, the thermal stress generated by the thermal expansion and contraction depending on the thermal gradient of the mold causes partial plastic deformation on the mold, which causes damage or fracture of the cast. Consequently, the thermal deformation along with thermal stress leads to thermal deformation of the cast itself. In this study, the temperature analysis of the cast and mold is simulated by FDM to control the thermal deformation and stress as a result of the thermal gradient of mold. Using the results from FDM simulation, the thermal deformation and stress are analyzed by FEM and, the optimal mold design with minimum thermal deformation of the cast is suggested.

• 대한기계학회논문집A
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• 제26권9호
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• pp.1943-1951
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• 2002

The casting roll design is one of the most important requirements in twin roll strip casting process. Coupled analyses of heat transfer and deformation for the cast roll are carried out by use of the finite element program MARC to examine the thermal stress and deformation. The effects of several factors on thermal stress and deformation are also investigated. The amount of thermal stress increases when the ni thickness increases and when the casting speed and the copper sleeve thickness decrease.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.619-623
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• 1996

This paper proposes the thermal characteristics of motor integrated spindle on high precision lathe and investigates the thermal deformation and the running error of spindle. The deformation and the running error of spindle shaft are continuously measured by the gapsensor mounted on machine. The temperature distribution is measured bythe thermal vision system and the thermocouple. The results show that the running error of spindle is dependent on the rotational speed and the thermal deformation.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2428-2437
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• 2000

In general, it is known that the portion of leakage loss is more than 20 % of total loss in scroll compressor. So far many studies have been done to improve the leakage problem and volumetric efficiency. In order to do this it is necessary that the leakage is exactly evaluated for conventional scroll model. Almost all studies that have been done were assumed that the clearance remains constant while operating. But in actual operating conditions, scroll wrap is deformed due to elevated refrigerant gas temperature. And this makes the leakage clearance change, so the leakage mass flow and the volumetric efficiency are also changed. In this study we assumed the steady state operating condition and obtain the average temperature and convection heat transfer coefficient in terms of involute angle. With these results, using finite element method we analyzed the heat transfer of scroll wrap, then did thermal deformation analysis. Then we obtain the leakage clearance and do the leakage and volumetric efficiency analysis. Compared with undeformed feature, we examine the effect of the thermal deformation on the leakage. The results say that the leakage mass flow for the case of considering thermal deformation is less than that for the unconsidered one, and this means that the leakage clearance is reduced due to thermal deformation.

• 한국생산제조학회지
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• 제20권5호
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• pp.541-546
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• 2011

This study was numerically investigated on thermal deformation of AC4C and AC7A aluminum alloy casting material for manufacturing the automobile tire mold. The metal casting device was used in order to manufacture the mold product of automobile tire at the actual industrial field. The temperature distribution and the cooling time of these materials were numerically calculated by finite element analysis. Thermal deformation with stress distribution was also calculated form the temperature distribution results. The thermal deformation was closely related to the temperature difference between the surface and inside of the casting. As shown by numerical analysis result, the thermal deformation of AC7A casting material became higher than AC4C casting material. In addition, the results of displacement and stress distributions appeared to be larger at the center parts of casting than on its sides because of the shrinkage caused by the cooling speed difference.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.341-344
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• 2008

Plastics is commonly used in consumer electronics because of it is high strength per unit mass and good productivity. But. using, transporting, and keeping of plastic component was happened post-deformation. As time goes by and temperature is changed, the post-deformation causes the problems of exterior design and performance. But, it is difficult to estimate the post-deformation by only thermal deformation analysis. Also, the estimation technique of the pest-deformation must be easily applied to product development and it should be reliable because development time of product is limited. In the paper. the process to predict the post deformation under cyclic thermal loadings was suggested. The process was applied to the real panel, and the deformation predicted by the analysis was compared with that of real test, which showed the possibility of applying the suggested process to predict the post deformation of plastic product under thermal loadings.

• 한국해양공학회지
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• 제8권1호
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• pp.33-40
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• 1994

Welding of structure produces welding residual stresses which influence buckling strength, brittle fracture strength and cold crack on the weld parts. Therefore, it is very important to accurately analyze the residual stress before welding in order to guarantee the safety of weldment. If the weld length is long enough compared to the thickness and the breadth of plate, thermal and mechanical behaviors in the middle portion of the plate are assumed to be uniform along the thickness direction(z-axis). Thus, the following conditions(so-called plane deformation) can be assumed for the plate except near its end;1) distributions of stress and strain are independent on the z-axis;2) plane normal to z-axis before deformation remains plane during and after deformation. In this paper, plane-deformation thermal elasto-plastic problem is formulated by being based on the finite element method. Moreover special regards and paid to the fact that material properties in elastic and plastic region are temperature-dependence. And the method to solve the plane-deformation thermal elasto-plastic problem is shown by using the incremental technique. From the results of analysis, the characterisics of distribution of welding residual stress and plastic strain with the production mechanism are clarified.

• 한국기계가공학회지
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• 제16권3호
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• pp.82-87
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• 2017

This study investigates thermal deformation due to fan shape of a hair dryer. In this study, thermal analysis showed that the shape of an electric fan results in lower temperature than that of a sieve frame. Among the shapes of electric fans, the temperature change decreases as the number of wings decreases. As a result of thermal deformation, model 4 (sieve frame shape) showed increased change of deformation compared to models 1, 2, and 3 (with electric fan shapes). Thus, the model 1 dryer with the sieve frame shape is shown to have the least durability among models 1, 2, 3, and 4. It is thought that the analysis results of this study can be applied to durability improvement and safer design of hair dryers.