• 한국자동차공학회논문집
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• 제14권5호
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• pp.145-154
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• 2006

Each part of drum brake system is loaded by continual mechanical force and thermal force every time of braking, so enough strength and stability are required. Thermal characteristic is one of the important factors in drum brake systems design. This paper presents the thermal performance such as temperature distribution and thermal contact stress of drum brake system considering several braking patterns; 80th heat braking test mode, heat fade braking test mode, general road mode, steep slope road mode and off road mode. Transient heat transfer analysis and Thermo elastic contact analysis is executed to obtain the temperature distribution, and to evaluate thermal stress of drum brake by using ABAQUS/Standard code. This procedure of analysis can effectively be used to improve the quality problem of brake system and to get design guideline of the new product.

• 마이크로전자및패키징학회지
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• 제20권2호
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• pp.33-38
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• 2013

In this study, both a finite element analysis and an experimental analysis are executed to investigate the mechanical characteristics of dielectric material effects on warpage. Also, viscoelastic material properties are measured by DMA and are considered in warpage simulation. A finite element analysis is done by using both thermal elastic analysis and a thermo-viscoelastic analysis to predict the nonlinear effects. For experimental study, specimens warpage of non-symmetric structure with body size of $22.5{\times}22.5$ mm, $37.5{\times}37.5$ mm and $42.5{\times}42.5$ mm are measured under the reflow temperature condition. From the analysis results, experimental warpage is not similar to FEA results using thermal elastic analysis but similar to FEA results using thermo-viscoelastic analysis. Also, its effect on substrate warpage is increased as core thickness is decreased and body size is getting larger. These FEA and the experimental results show that the nonlinear characteristics of dielectric material play an important role on substrate warpage. Therefore, it is strongly recommended that non-linear behavior characteristics of a dielectric material should be considered to control warpage of FCBGA substrate under conditions of geometry, structure and manufacturing process and so on.

• 한국정밀공학회지
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• 제29권10호
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• pp.1137-1143
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• 2012

Creep characteristic is an important failure mechanism when evaluating engineering materials that are soft material as polymers or used as mechanical elements at high temperatures. One of the popular thermo-plastic polymers, Acrylonitrile Butadiene Styrene (ABS) which is used broadly for machine elements material, as it has excellent mechanical properties such as impact resistance, toughness and stiffness compared to other polymers, was studied for creep characteristic at different levels of stress and temperatures. From the experimental results, the creep limit of ABS at room temperature is 80 % of tensile strength which is higher than PE and lower than PC or PMMA. Also the creep limits decreased to linearly as the temperatures increased, up to $80^{\circ}C$ which is the softening temperature of Butadiene ($82^{\circ}C$). Also the secondary stage of creep among the three creep stages for different levels of stress and temperature was non-existent which occurred for many metals by strain hardening effect.

• 한국강구조학회 논문집
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• 제18권3호
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• pp.395-403
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• 2006

최근 건설되는 강교량은 지간의 장대화 및 교량으로서의 기능은 물론이고 외적 조형미, 유지관리, 공사기간과 수명주기 비용 등을고려한 구조적 단순함을 요한다. 이러한 요구를 충족시키기 위해 극후판이나 TMCP 강과 같은 고성능 강의 사용이 요구된다. TMCP (Thermo-Mechanical Control Proces)법에 의해 제조되는 TMCP 강은 탄소당량이 적고, 조직이 미세하며, 강도 및 인성이 좋다. 최근에는 인장강도 60MPa급의 고강도 TMCP 강인 SM570-TMC 강이 개발되어 토목구조물에 일부 적용되고 있으며, 점차 그 영역을 확장하려는 추세에 있다. 하지만 이러한 고강도 TMCP 강을 강구조물에 적용하기 위해서는 그 재료적 특성뿐만 아니라 용접 시 발생하는 접합부의 역학적 특징을 명확히 할 필요가 있다. 따라서 본 연구에서는 고온인장실험을 통해서 SM570-TMC 강의 고온시의 기 계적 특성을 조사하였고, 이를 잔류응력 특징을 명확히 하였다.

• 대한기계학회논문집A
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• 제38권2호
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• pp.157-166
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• 2014

경수로 핵연료가 원자로내에서 연소되는 동안 핵연료 펠릿에서부터 피복관까지 온도해석은 핵연료 안전 해석에 있어 중요한 요소이며, 경수로 핵연료 온도 해석을 하기 위해서는 간극 모델 개발이 필수적이다. 간극 열전도도는 특성상 간극 두께값에 의존적이게 되며 이러한 특성으로 인해 다차원 간극 열전도도 모델이 비선형적 거동을 보인다. 본 연구에서는 선형화된 다차원 간극 열전도도 모델 개발을 위해 가상 연결 간극 요소를 제안하였다. 제안된 간극 연결 요소에 간극 열전도도를 적용하기 위해 등가 열전달 계수를 정의하였다. 제안된 모듈을 평가하기 위해 상용코드 ANSYS APDL 을 이용하여 열-구조 연계 해석 모듈을 구현하였으며, 다양한 예제를 통해 정확성과 수렴성을 평가하였다.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.298-305
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• 2000

The functionally graded material (FGM) is the new concept for a heat resisting material. FGM consists of ceramics on one side and metal on the other. A composition and microstructure of an intermediate layer change continuously from ceramics to metal at the micron level. This study is carried out to analyze the thermal shock characteristics of functionally graded PSZ/ metal composites. Heat-resistant property was evaluated by gas burner heating test using $C_2H_2/O_2$ combustion flame. The ceramic surface was heated with burner flame and the bottom surface cooled with water flow. Also, the composition profile and the thickness of the graded layer were varied to study the thermo mechanical response. Furthermore, this study carried out the thermal stress analysis to investigate the thermal characteristics by the finite element method. Acoustic emission (AE) monitoring was performed to detect the microfracture process in a thermal shock test.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3187-3190
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• 2007

Elastin-Like polypeptide (ELP) composed of elastin-based repeating units is an artificial biomaterial which is biocompatible and non-immunogenic. ELP shows a characteristic inverse phase transition between hydrophobic and hydrophilic phase by external stimuli such as salt, pH and temperature. In this study, ELP coated PS (polystyrene) beads are packed in tubing and the thermo -responsive flow characteristics of the packed bed are investigated. Preliminary test results show that the control of the fluid flow can be achieved by using the temperature driven phase transition effect of the ELP coated beads in a microchannel.

• Composites Research
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• 제26권1호
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• pp.54-59
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• 2013

This study deals with effect of plasma treatment on the properties of unidirectional ligno cellulosic fabric Hildegardia Populofolia (HDP) fabric. Thermal stability of the fabric was determined by differential scanning calorimetry (DSC) and Thermo gravimetric analysis (DSC). Morphological properties was analyzed by SEM analysis and found that the surface was rough upon plasma treatment which provides good interfacial adhesion with matrix during composite fabrication. Thermal stability and mechanical properties of the plasma treated fabric slightly increases compare to alkali and untreated fabric. It was observed that tensile properties of the fabric increases upon plasma treatment due to the formation of rough surface. SEM analysis indicates formation of rough surface on plasma treatment which helps in increasing the interfacial interaction between the matrix (hydrophobic) and fabric (hydrophilic).

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.976-981
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• 2006

In case of attaching thermoelectric module and heat source, the polymer pad is attached on the $Al_2O_3$ plate, which is cooling side of thermoelectric module, in order to enhance mechanical safety of the system. It is impossible to calculate the exact distribution of temperature and flow pattern of inner gap of thermoelectric module. Therefore CFD(Computational Fluid Dynamics) analysis was executed to determine the thermo-fluid phenomena and distribution by Fluent. As the result of these analysis, heat transfer was dominated by conduction and the difference of temperature was linear distribution according to the thickness of polymer sheet.

• 마이크로전자및패키징학회지
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• 제13권3호
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• pp.39-45
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• 2006

다양한 에폭시 수지를 함유한 언더필의 열적 특성을 시차주사열량측정법, 열중량측정법, 동적-기계적 분석법, 열적-기계적 분석법과 같은 열 분석법을 이용하여 분석하였다. 또한, 언더필과 FR-4기판 사이의 접합 강도를 측정하였다. Cycolaliphatic 에폭시 수지를 함유한 언더필의 유리 전이 온도가 cycolaliphatic 에폭시 수지를 함유하지 않은 언더필의 유리 전이 온도보다 낮음을 확인할 수 있다. 대기로부터 유입된 산소와 열화된 폴리머 사이의 화학적 반응으로 인하여 언더필의 열적 감소 반응이 두 번 발생하는 것을 확인할 수 있다. Cycolaliphatic 에폭시 수지를 함유한 언더필의 열팽창 계수가 cycolaliphatic 에폭시 수지를 함유하지 않은 언더필의 열팽창 계수보다 높음을 확인할 수 있다. 과도한 경화 온도는 에폭시 수지의 경계면을 약하게 하여 에폭시 수지의 기계적 특성의 변화를 초래하게 되고 언더필과 FR-4 기판 사이의 접합 특성을 저하시키게 된다.