• 대한기계학회논문집
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• 제19권9호
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• pp.2133-2141
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• 1995

The thermo-mechanical fatigue tests were performed on the specimens extracted from 1.5Cr-0. 67Mo-0.33V alloy. The characteristics of thermo-mechanical fatigue crack propagation were examined and reviewed in view of fracture mechanics. The results obtained from the present study are summarized as follows : (1) The propagation characteristics of isothermal low-cycle fatigue crack are dominated by .DELTA.J$_{f}$ in case of PP waveform, and .DELTA.J$_{c}$ in case of CP waveform. (II)The propagation characteristics of thermo-mechanical fatigue crack are dominated by .DELTA.J$_{c}$ for in-phase case, and by .DELTA.J$_{c}$ for out-of-phase. The present results were in good agreement with the equation of propagation law for isothermal low-cycle fatigue crack in case of thermo-mechanical fatigue.tigue.e.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.22-25
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• 2005

In this research, a wafar-level transfer method of cantilever array on a conventional CMOS circuit has been developed for high density probe-based data storage. The transferred cantilevers were silicon nitride ($Si_3N_4$) cantilevers integrated with poly silicon heaters and piezoelectric sensors, called thermo-piezoelectric $Si_3N_4$ cantilevers. In this process, we did not use a SOI wafer but a conventional p-type wafer for the fabrication of the thermo-piezoelectric $Si_3N_4$ cantilever arrays. Furthermore, we have developed a very simple transfer process, requiring only one step of cantilever transfer process for the integration of the CMOS wafer and cantilevers. Using this process, we have fabricated a single thermo-piezoelectric $Si_3N_4$ cantilever, and recorded 65nm data bits on a PMMA film and confirmed a charge signal at 5nm of cantilever deflection. And we have successfully applied this method to transfer 34 by 34 thermo-piezoelectric $Si_3N_4$ cantilever arrays on a CMOS wafer. We obtained reading signals from one of the cantilevers.

• 한국전산구조공학회논문집
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• 제15권4호
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• pp.727-739
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• 2002

강자성 판의 자기-열-탄성 상호작용을 고찰하기 위하여 자기-열-탄성에 관한 일반화된 변분원리에 기초한 이론적인 모델이 제안되었다. 자탄성 선형화이론과 섭동법을 사용하여, 온도장과 자기장으로 재하된 단순지지 강자성 평판의자-탄성 좌굴과 자기-열-탄성 좌굴거동을 해석하였다. 또한 해석적인 고찰이 어려운 보다 복잡한 강자성 판의 자기-열-탄성 거동을 모사하기 위하여 비선형 유한요소 모형을 개발하였다. 이 유한요소모형을 이용하여 유한한 강자성 판의 자기-열-탄성 ？과 좌굴거동 그리고, 이에대한 온도장과 자기장의 영향에 대하여 고찰하였다.

• Corrosion Science and Technology
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• 제18권5호
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• pp.182-189
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• 2019

A thin spray coating of inorganic black lithium polysilicate (IBLP) on black anodized AZ31B magnesium alloy was fabricated for better corrosion resistance and thermo-optical properties for thermal control of spacecraft components. The morphology of the specimens with and without IBLP-based spray coating was characterized by SEM-EDS techniques. Impedance and potentiodynamic measurements on the specimens revealed better corrosion resistance for the specimen with a thin coating of lithium polysilicate. This was primarily due to the presence of lithium polysilicate inside the micro-cracks of the black anodized specimen, restricting the diffusion paths for corrosive media. Environmental tests, namely, humidity, thermal cycling, thermo vacuum performance, were used to evaluate the space-worthiness of the coating. The thermo-optical properties of the coating were measured before and after each environmental test to ascertain its stability. The specimen with an IBLP-based spray coating showed enhanced thermo-optical properties, greater than ~0.90. Hence, the proposed coating demonstrated better handling, better corrosion resistance, and space-worthiness during the pre-launch phase owing to its improved thermo-optical properties.

• 설비공학논문집
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• 제21권4호
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• pp.236-242
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• 2009

In finishing work, defects are often taken place by many factors. One of them is the thermo-humidity condition on the work surface as coating and anointing adhesives. Thus, the condition of thermo-humidity on work surface should be checked prior to the finishing work. However, many construction companies show a tendency to overlook it because not only are measurement tools so expensive but they don't have skilled hands about those tools. Therefore, we propose the measurement method that makes it easy to recognize surface thermo-humidity condition so as to reduce constructional flaws. And then we test this product. The test progresses to four stages with various conditions. We evaluate its usefulness and application possibility of this product in the field.

• 한국광학회지
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• 제17권5호
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• pp.469-474
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• 2006

본 논문에서는 실리카 기반의 다중모드 간섭기를 이용하여 적은 초과손실을 갖는 $1{\times}16$ 마하젠더 스위치에 대한 설계 및 측정결과에 대하여 논하였다. 제작된 $1{\times}16$ 마하젠더 스위치는 마하젠더 간섭계(Mach-Zehnder Interferometer, MZI) 구조를 갖는 $2{\times}2$ 열광학스위치를 단위소자로 하였으며, 15개의 단위소자를 이용하여 4단(stage)으로 구성하였다. 먼저 광분배기와 $2{\times}2$ MZI 열광학 스위치등의 개별적인 특성을 파악하였고, 그 결과를 전체 소자의 설계에 적용함으로써 보다 좋은 성능을 얻을 수 있었다. 제작된 다중모드 간섭기를 이용한 MZI 구조의 단위스위치 당 초과손실은 최소 -0.5dB로 측정되었다.

• 한국전산구조공학회논문집
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• 제20권6호
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• pp.683-690
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• 2007

위상 최적화 기술은 제품의 초기단계의 개념설계에 유용한 기술이며, 주로 구조물의 탄성을 고려한 분야를 중심으로 개발되었다. 그러나 일반적인 기계의 정밀도가 향상됨에 따라 열적인 영향을 함께 고려할 경우가 많아지게 되어, 열과 탄성계를 동시에 고려하는 위상 최적설계가 필요하다. 본 연구에서 균질화법을 이용하여 열-탄성계를 고려한 위상 최적설계를 해석하였다. 열-탄성 문제에서는 열전달 해석과 구조해석을 고려하는 문제이므로 열전달 재료 물성치와 구조 재료 물성치를 함께 사용하였다. 가동에너지를 기계적인 변위 또는 응력으로 변환하는 트랜스듀서인 액츄에이터의 설계에 적용하였으며, 열계와 탄성계 그리고 열-탄성계를 동시에 해석한 설계 결과를 얻었다. 얻어진 각각의 결과를 동일한 하중조건으로 재해석한 결과, 열-탄성계를 고려하였을 경우가 각각의 계를 고려했을 경우보다 개선된 성능을 가진다.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1653-1665
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• 2002

One of the most significant problems in the processing of composite materials is residual stresses. The residual stresses may be high enough to cause cracking in the matrix even before external loads are applied and can degrade the integrity of composite structures. In this study, thermo-viscoelastic residual stresses occurred in the polymeric composite cylinder are investigated. This type of structure is used for the launch vehicle fuselage. The time and degree of cure dependent thermo-viscoelastic constitutive equations are developed and coupled with a thermo-chemical process model. These equations are solved with the finite element method to predict the residual stresses in the composite structures during cure. A launch vehicle experiences high thermal loads during flight and re-entry due to aerodynamic heating or propulsion heat, and the thermal loads may cause thermal buckling on the structure. In this study the thermal buckling analysis of composite cylinders are performed. Two boundary conditions such as all clamped and all simply supported are used for the analysis. The effects of laminates stacking sequences, shapes and residual stresses on the critical buckling temperatures of composite cylinders are investigated. The thermal buckling analysis is performed using ABAQUS.

• Journal of Acupuncture Research
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• 제28권2호
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• pp.133-141
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• 2011

Objectives : Although the thermo-sensitivity test in Well points in 12 Meridians(井穴知熱感度測定法) has been used for several decades, it is still performed by a manual way, and lack in objectivity consequently. To make it more objective, accurate and convenient test, we have developed a novel system to test thermo-sensitivity in Well points. Methods : To enhance the blindness of the test, we made a shielded system which give heat to some fingers of subjects in random way. To perform the test in quantitative manner, we developed a fully automated, computer-controlled system composed of heating bulbs and response button array. Results : The developed system showed linearity in heating the finger phantom. It also gave acceptable but interesting features in pilot tests with several young adult subjects. Conclusions : By the developed system, we could improve objectivity and convenience of the thermo-sensitivity test in Well points.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.100-105
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• 2002

This paper predicts the material properties of spatially reinforced composites (SRC) and analyzes the thermo-elastic behavior of a kick motor nozzle manufactured from that material. To find the appropriate SRC structure for the nozzle throat that satisfies given design conditions, the equivalent material properties of the SRC are predicted using the superposition method for those of rod and matrix. Studied are the elastic behavior, temperature distribution, and thermo-elastic behavior of a kick motor nozzle composed of carbon/carbon SRC as a throat part. The elastic deformation of the nozzle composed of 3D carbon/carbon SRC shows asymmetry in a circumferential direction. However, 4D carbon/carbon SRC nozzle shows uniform deformation in the circumferential direction. Stress concentration in connecting parts of the kick motor nozzle is ultimately high due to the high temperature gradient in each connecting part. The thermo-elastic deformations of both the 3D and the 4D SRC nozzles are uniform in the circumferential direction due to the isotropy of CTE of each SRC. The deformation of the 3D SRC nozzle is a slightly smaller than that of the 4D SRC nozzle in the nozzle throat, which is favorably effective on rocket thrust. The circumferential stress is the most critical component of the kick motor nozzle. The 4D SRC nozzle having 1,1,1,1.7 diameters in each direction has the smallest circumferential stress among several SRC nozzles.