• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.39-48
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• 2016

In this paper, we propose thermal resistance compact model of FinFET structure that has hexagon shaped source/drain. The heating effect and thermal properties were increased by reduced size of the device, and thermal resistance is an important factor to analyze the effect and the properties. The heat source and each contact that is moved heat out were set up in transistor, and domain is divided by the heat source and the four parts of contacts : source, drain, gate, substrate. Each contact thermal resistance model is subdivided as a easily interpretable structure by analyzing the temperature and heat flow of the TCAD simulation results. The domains are modeled based on an integration or conformal mapping method through the structure parameters according to its structure. First modeled by analyzing the thermal resistance to a single fin, and applying the change in the parameter of the channel increases to improve the accuracy of the thermal resistance model of the multi-fin/ finger. The proposed thermal resistance model was compared to the thermal resistance by analyzing results of the 3D Technology CAD simulations, and the proposed total thermal resistance model has an error of 3 % less in single and multi-finl. The proposed thermal resistance model can predict the thermal resistance due to the increase of the fin / finger, and the circuit characteristics can be improved by calculating the self-heating effect and thermal characterization.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.973-976
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• 2011

In this paper, the conjugated heat transfer anslysis was performed about an electric heater used in a combustion test equipment of a combustor engine to figure out a physical phenomenon that heater coil was periodically cut during heating test. The result of analysis is that the temperature of coil at coil inlet region was increased locally because the velocity of air was slow in that region. The coil of heater was moved to 25mm downstream so that the structure stability of coil was assured by the decrease of the coil temperature due to increase of an air velocity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.179-185
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• 2015

The main objective of thermal design for a space-borne FPA(Focal Plane Assembly) is to provide stable thermal environment during imaging operation and thus maintain the image quality. An FPA must be maintained within its operating temperature range and cooled down to its initial temperature soon enough for the next imaging operation. This paper describes the study result on performing trade-off studies for FPA thermal design by using simplified thermal node analysis about FPA preliminary design. It also describes the verification results of the study by comparing thermal analysis results and trade-off study results. According to results, we can conclude that this approach is useful for simple and quick trade-off studies without thermal analysis based on thermal math models.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.103.2-103.2
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• 2015

10-3 Pa 이하의 고진공 환경과 $180^{\circ}C$ 이하의 극저온 환경에서 대형정지궤도위성의 고온 열평형 환경구현을 위한 열제어패널이 설계되었다. 열제어패널은 가로 2.2 m, 세로 2.6 m, 두께 2 mm의 구리판에 구리 튜브가 브레이징되어 있는 형태로 설계되었으며, 지상에서 6 m 이상의 높이에 설치되고 위성의 위치에 따라 이동이 가능해야 하기 때문에, 별도의 지지 구조물이 함께 설계되었다. 따라서, 열제어패널 설치 및 고정을 위한 지지구조물의 경우 160 kg의 무게를 견뎌내야 하며 이동 및 설치에 있어 구조적인 안전성이 확보 되어야 한다. 이에 본 연구에서는 상용유한요소해석 프로그램을 사용하여 열평형시험 시 위성체 상단부의 고온 환경모사를 위한 열제어패널 지지구조물에 대한 구조 안전성을 확인 하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.313-327
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• 2008

Thermo-mechanical coupled behavior of an underground structure during a fire accident have not been fully understood yet. Moreover, when such a thermo-mechanical coupled behavior is not considered in numerical analyses based on conventional heat transfer theory, fire-induced damage zone in an underground structure can be considerably underestimated. This study aims to develop a FEM-based numerical technique to simulate the thermo-mechanical coupled behavior of an underground structure in a fire accident. Especially, an element elimination model is newly proposed to simulate fire-induced structural loss together with a convective boundary condition. In the proposed model, an element where the maximum temperature calculated from heat transfer analysis is over a prescribed critical temperature is eliminated. Then, the proposed numerical technique is verified by comparing numerical results with experimental results from real fire model tests. From a series of parametric studies, the key parameters such as critical temperature, element size and temperature-dependent convection coefficients are optimized for the RABT and the RWS fire scenarios.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.1
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• pp.23-32
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• 1987

기계,구조물의 신뢰성을 향상시키는 입장에서, 최근에 특히 진동문제가 크로즈업되고 있다. 이것 은 기계, 구조물이 고속화, 대형화, 대용량화함에 따라 종래의 기술만으로는 통용이 되지않기 때 문이라고 생각한다. 이러한 이유로 기계, 구조물의 동력학적 검토를 위해 수치해석기술과 실험해 석기술이 근년에 대단히 비약적으로 발전하고 있다. 이러한 해석기술의 진보를 뒷받침하는 것은 근년의 계산기 및 그 이용기술이다. 즉, 수치해석분야에서 Cray RAN을 시초로 하는 각종전자계 측기기, 고성능미니컴퓨터와 시계열통계해석기술 및 모우도 해석기술이다. 특히 모우드해석에 관 해서는 근년의 진보가 현저하고, 종래의 간단한 가진실험 데이터로부터의 모우도, 파라미터(고유 치, 고유감쇠비, 고유모우드)의 추출에 그치지 않고, 진동응답예측(simulation)과 유한요소법과의 결합이라고 하는 광범위한 기술내용의 포함하는 중요한 기술이 되고 있다. 여기에서는, 이 모우 드해석 특히 실험적 모우드해석기술을 기계구조물에 어떻게 응용할것인가에 대해서 설명한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.115-124
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• 2003

To guarantee the proper functions of a satellite in the extreme space environment, the several test models are developed generally. There are advantages that the design and the analysis of Flight Model(FM) can be validated through these test models, and the functional reliabilities can be increased by reflecting the modifications on the final design of FM. The integration and test of Structure & Thermal Model(STM) of KOMPSAT, being currently developed, have been completed. In this paper, the processes of design/analysis and integration of the STM propulsion system, one of the KOMPSAT modules, are described.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.94-102
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• 2023

A nylon wire holding and release mechanism (HRM) has been widely used for deployable applications of CubeSat owing to its simplicity and low cost. In general, structural safety of solar panel with an HRM has been designed by performing structural analysis under a launch environment. However, previous studies have not performed thermal analysis for HRM in an on-orbit environment. In this study, Launch and Early Orbit Phase (LEOP) thermal analysis was performed to evaluate thermal stability of the mechanism in the orbital thermal environment of the pogo pin-based HRM applied to CubeSat. In addition, the effectiveness of the thermal design and performance of the pogo pin-based HRM were verified through a thermal vacuum test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1119-1127
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• 2010

In this paper, the design and nonlinear simulation of a multistable electromagnetic microactuator, which provides four stable equilibrium positions within its operating range, have been discussed. Quadstable actuator motion has been made possible by using both X- and Y-directional bistable structures with snapping curved beams. Two pairs of the curved beams are attached to an inner frame in both X- and Y-directions to realize independent bistable behavior in each direction. For the actuation of the actuator at the micrometer scale, an electromagnetic actuation method in which Lorentz force is taken into consideration was used. By using this method, micrometer-stroke quadstability in a plane parallel to a substrate was possible. The feasibility of designing an actuator that can realize quadstable motion by using the electromagnetic actuation method has been thoroughly clarified by performing nonlinear static and dynamic analyses and electrothermal coupled-field analysis of the multistable microactuator.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.535-541
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• 2010

In this paper, we have derived a continuum-based adjoint design sensitivity of general performance functionals with respect to Young' modulus and heat conduction coefficient for steady-state nonlinear thermoelastic problems. An adjoint equation for temperature and displacement fields is defined for the efficient computation of the coupled field design sensitivity. Through numerical examples, we investigated the mesh dependency of the topology optimization method in the thermoelastic problems. Also, comparing the dominant loading cases of thermal and mechanical ones, the loading dependency of topology design optimization in coupled multi-physics problems is investigated.