• Journal of the Korean Magnetics Society
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• v.20 no.2
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• pp.75-82
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• 2010

A recent progress on the prediction of the thermal stability of a nanostructured exchange-coupled trilayer is reviewed. An analytical/numerical combined method is used to calculate its magnetic energy barrier and hence the thermal stability parameter. An important feature of the method is the use of an analytical equation for the total energy that contains the magnetostatic fields. Under an assumption of the single domain state, the effective values of all the magnetostatic fields can be obtained by averaging their nonuniform values over the entire magnetic volume. In an equilibrium state, however, it is not easy to calculate the magnetostatic fields at the saddle point due to the absence of suitable methods of the accessing its magnetic configuration. This difficulty is overcome with the use of equations that link the magnetostatic fields at the saddle point and critical fields. Since the critical fields can readily be obtained by micromagnetic simulation, the present method should provide accurate results for the thermal stability of a nanostructured exchange-coupled trilayer.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.172-178
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• 2017

Thermal property is one of the important characteristic in the field of energetic materials. As the energy material is released during decomposition, DSC(Differential Scanning Calorimetry) is frequently used for the thermal analysis. In case of the dynamic DSC measurements, thermal dynamic change like melting is prevented from the thermal property measurements. And due to the predicting kg scale, the conditions of the heat exchange with the environment significantly is changed. In this study, As the method to resolve the problem, we predict the thermal aging property using the AKTS thermokinetic program from DSC measurements which performed isothermal method. Predicting the thermal aging properties from ARC(Accelerating Rate Calorimetry) measurement, we compare two results.

• Polymer(Korea)
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• v.37 no.1
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• pp.15-21
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• 2013

Encapsulation of a paraffin wax core as a phase change material with polystyrene shell and the its thermal characteristics caused by the encapsulation were studied. For the nanoencapsulation, the miniemulsion polymerization method was selected. The factors affecting the thermal properties of prepared nanocapsule particles of phase change material were analysed in aspect of the structure of crosslinking agents, amounts of surfactant, ratio of paraffin wax to monomer, and hydrophilicity of initiators. It was assumed that Oswald ripening plays the most important role in the changes of particle size, particle morphology, and thermal capacity of nanocapsule core. It was elucidated that the thermal capacity was also dependent on the hydrophilicity and crosslinking density of polystyrene shell components.

• Fire Science and Engineering
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• v.34 no.3
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• pp.28-34
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• 2020

In this study, an ISO 5660-1 cone calorimeter experiment was conducted to examine the effects of changes in flow and thermal thickness around solid combustibles on heat release rate characteristics. Polymethyl methacrylate (PMMA) is a solid combustible material that does not generate char during the combustion reaction. Hence, it was selected for the experiment, and the thermal penetration depth was calculated to distinguish the thermal thickness of PMMA. Furthermore, the thermal decomposition characteristics were analyzed by measuring the heat release rate measured during the combustion of PMMA. This was performed after generating the forced flow around the combustibles by setting the duct flow of the cone calorimeter to 12, 24, and 40 L/s. The results confirmed that the thermal release rate of the thermally thin combustible material was not significantly affected by the change in the surrounding flow. Hence, the thermally thick combustible material was significantly affected by the change in the flow rate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.5
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• pp.437-446
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• 2021

As flying vehicle's speed is getting faster, the magnitude of aerodynamic heating is getting bigger. High-speed vehicle's exterior skin is heated to hundreds of degrees, and electrical equipments inside the vehicle are heated, simultaneously. Since allowable temperature of electrical equipments is low, they are vulnerable to effect of aerodynamic heating. These days, lots of techniques are applied to estimate temperature of electrical equipments in flight condition, and to make them thermally safe from heating during flight. In this paper, new model building technique for thermal safety analysis is introduced. To understand internal thermal transient characteristic of electrical equipment, simple heating experiment was held. From the result of experiment, we used our new building technique to build thermal analysis model which reflects thermal transient characteristic of original equipment. This model can provide internal temperature differences of electrical equipment and temperature change of specific unit which is thermally most vulnerable part in the equipment. So, engineers are provided much more detailed thermal analysis data for thermal safety of electrical equipment through this technique.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.241-248
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• 2023

The value of experimentally obtained data becomes highest when they are properly analyzed based on valid logics. Many physical and chemical properties such as electrical and magnetic properties, chemical reaction rates, etc. are known to be thermally activated; thus, a proper understanding of thermally-activated processes is of importance. However, there are still a number of papers published with falsely analyzed data. In this contribution, we would like to revisit the meaning of thermally-activated processes, and then reanalyze a data set published misinterpreted. By showing a step-by-step procedure for the reanalysis, we would like to help researchers who may come across such data in the future not to make mistakes in their analysis.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.67.2-67.2
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• 2010

F doped ZnO (FZO)박막은 rf magnetron sputtering을 이용하여 ZnO 박막에 F의 도핑량 변화에 따른 효과와 전기적, 광학적 및 열적 특성에 대하여 고찰하였다. 열처리 전의 박막에서는 $CF_4$ gas가 0.1%일 때 가장 좋은 전기적 특성을 보였고, 이는 대부분의 F이 O와 치환을 하여 전기적 특성이 우수해지는 것으로 보인다. 그러나 일반적으로 열처리 전 FZO 박막은 낮은 전기적 특성을 가지며, 열처리 후에는 전기적 특성이 많이 향상되었고, 특히 홀 이동도가 $42.6cm^2/Vs$의 높은 값을 가졌다. 또한 F 함량이 증가할수록 광학적 특성은 좋아졌지만, 구조적 특성은 열처리 전 후를 비교할 때 큰 변화가 없었다. 이 연구를 통해서 $40cm^2/Vs$이상의 높은 홀 이동도를 가지고, 열적으로 안정한 ZnO계 박막의 제조가 가능하였다.

• Journal of the Korean Vacuum Society
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• v.4 no.1
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• pp.32-39
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• 1995

SnO2/AI/Ag/AI/SnO2층 구조로 이루어진 열처리 가능한 열선반사막을 직류 스퍼터링법에 의해 soda-lime silicate 유리위에 형성시켰다. 이 코팅유리를 $650^{\circ}C$에서 열처리하면 가시광선 투과율 85%이상, plasma wavelength 970nm 이하를 얻을 수 있었다. 따라서 이 구조의 막은 유리 곡가공에 견디는 열적 안정성을 나타내었으며, 코팅유리의 열처리에 따른 전기적 특성 및 열적 안정성은 각각 Ag와 AI층의 두께에 의존하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.106-106
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• 2003

반도체 소자의 고집적화에 따라 채널길이와 배선선 폭은 점차 줄어들고, 이에 따라 단채널효과, 소스/드레인에서의 기생저항 증가 및 게이트에서의 RC 시간지연 증가 등의 문제가 야기되었다. 이를 해결하기 위하여 자기정렬 실리사이드화(SADS) 공정을 통해 TiSi2, CoSi2 같은 금속 실리사이드를 접촉 및 게이트 전극으로 사용하려는 노력이 진행되고 있다. 그런데 TiSi2는 면저항의 선폭의존성 때문에, 그리고 CoSi2는 실리사이드 형성시 과도한 Si소모로 인해 차세대 MOSFET소자에 적용하기에는 한계가 있다. 반면, NiSi는 이러한 문제점을 나타내지 않고 저온 공정이 가능한 재료이다. 그러나, NiSi는 실리사이드 형성시 NiSi/Si 계면의 산화와 거침성(roughness) 때문에 높은 누설 전류와 면저항값, 그리고 열적 불안정성을 나타낸다. 한편, 초고집적 소자의 배선재료로는 비저항이 낮고 electro- 및 stress-migration에 대한 저항성이 높은 Cu가 사용될 전망이다. 그러나, Cu는 Si, SiO2, 실리사이드로 확산·반응하여 소자의 열적, 전기적, 기계적 특성을 저하시킨다. 따라서 Cu를 배선재료로 사용하기 위해서는 확산방지막이 필요하며, 확산방지재료로는 Ti, TiN, Ta, TaN 등이 많이 연구되고 있다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.110-110
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• 2003

LED의 품위가 높아지고 고 광방출을 위한 전기적 출력이 높아질수록 LED 자체에서 발생하는 열이 아주 중요한 요소로 제출되고 있다. 본 실험에서는 여러 가지 LED 모델의 열적특성을 분석하여 가장 최적화된 모델을 생성하려고 한다 실험방법은 유한요소법을 사용하는 소프트웨어 ANSYS를 이용하여 여러 가지 LED 모델을 생성하고 입력조건과 경계조건을 집어넣고 해석한 후 결과를 분석하여 각종 모델의 최고 온도를 알 수 있다 그 다음 여러 가지 모델의 최고 온도를 비교하여 가장 최적화된 LED모델을 발견하고 또한 열적으로 영향 주는 요소들을 도출 해낼 수 있다. 이러한 분석은 금후 고휘도 LED램프생산성에 중요한 기반기술로 사료된다.