• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.251-254
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• 2009

Thermal performance of a thermosiphon for medium-temperature solar thermal application was investigated. The working fluid was Dowtherm A and the container was made of STS 316L. The thermosiphon had a outer diameter of 12.7 mm and a total length of 2 m, where the evaporator and the condenser had the same length of 0.3 m and the adiabatic section was 1.4 m. Both the evaporator and the condenser were aligned horizontal with an elevation difference of 0.18 m to utilize the gravitational force for the working-fluid return. The optimum fill charge ratio of the working fluid was investigated to obtain the maximum heat transport with the lowest thermal resistance. The maximun input thermal load was 500 W and thermal resistance was $0.60^{\circ}C/W$.

• 한국의류산업학회지
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• 제4권6호
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• pp.544-549
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• 2002

By the movable thermal manikin developed by China Dong Hua university, the laws of clothing thermal insulation influenced by dressing poses are studied. It is found that $I_a$ on nude thermal manikin has no relation to testing pose as a whole (notable level is 5%), while the change of testing pose influences $I_a$ value on parts of body obviously. The testing result $I_{cle}$ on clothed thermal manikin has relation to testing pose. The $I_{cle}$ value of the whole body in seated pose decreases 20 percent compared with that in standing pose (notable level is 1%). In view of heat transmission theory, the reasons are pointed out based on the knowledge of heat transmission.

• Journal of Welding and Joining
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• 제5권3호
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• pp.28-37
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• 1987

To clarify the debonding phenomena of clad steel, the effect of thermal treatment (temperature, holding time) on the interfacial strength of clad steel was preliminarily investigated. From this study, it was confirmed that the interfacial strength of clad steel was deteriorated by thermal treatment and the amount of strength deteriorated, depending on the condition of thermal treatment, could be evaluated by the following equation. ${\sigma}_{ HT}/{\sigma}_{i}/=A_{0}-A\;exp(-Q/RT)log(t/t_{0})$ This equation implies that temperature has a far strong effect on strength deterioration than tiem. The deterioration of interfacial strength of clad steel after thermal treatment may be derived from the thermal stress caused by the difference in thermal expansion coefficient between component materials and microstructural change along the interface.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.643-646
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• 1999

Downstream surface of the concrete gravity dam receives thermal stress due to atmosphere temperature change. So in this paper, the behaviors of crack located in the downstream surface were investigated, when considering the temperature change.

• 한국정밀공학회지
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• 제19권1호
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• pp.56-64
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• 2002

Machine tools are engineered to give high dimensional accuracy in machining operation. However, errors due to thermal effects degrade dimensional accuracy of machine tools considerably, and many machine tools are equipped with thermal error compensation function. In general, thermal errors can be generated in the angular directions as well as linear directions. Among them, thermal errors in the angular directions contribute a large amount of error components in the presence of offset distance as in the case of Abbe error. Because most of thermal error compensation function is based on a good correlation between temperature change and thermal deformation, angular thermal deformation is often to be the most difficult hurdle for enhancing compensation accuracy. In this regard, this paper investigates the effect of thermal bending to total thermal error and gives how to deal with thermally induced bending effects in thermal error compensation.

• JSTS:Journal of Semiconductor Technology and Science
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• 제11권3호
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• pp.146-152
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• 2011

Thermal stability of $Ge_2Sb_2Te_5$ (GST) and $SiO_2$ doped GST (SGST) films for phase change random access memory applications was investigated by observing the change of surface roughness, layer density and composition of both films after isothermal annealing. After both GST and SGST films were annealed at $325^{\circ}C$ for 20 min, root mean square (RMS) surface roughness of GST was increased from 1.9 to 35.9 nm but that of SGST was almost unchanged. Layer density of GST also steeply decreased from 72.48 to 68.98 $g/cm^2$ and composition was largely varied from Ge : Sb : Te = 22.3 : 22.1 : 55.6 to 24.2 : 22.7 : 53.1, while those of SGST were almost unchanged. It was confirmed that the addition of a small amount of $SiO_2$ into GST film restricted the deterioration of physical and chemical properties of GST film, resulting in the better thermal stability after isothermal annealing.

• 접착 및 계면
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• 제3권2호
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• pp.30-39
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• 2002

실리카로 보강된 천연고무 가황물에서 가황촉진제의 양이 열노화에 의한 가교밀도의 변화에 미치는 영향에 대해 연구하였다. 또한 실란커플링제의 영향도 조사하였다. 가황촉진제로는 N-tert-butyl-2-benzothiazole sulfenamide(TBBS)를 실란 커플링제로는 bis-(3-(triethoxysilyl)-propyl)-tetrasulfide(TESPT)를 사용하였다. 가황물을 열노화 시키면 가교밀도는 증가하였고 노화 온도가 높을수록 그 변화 정도는 컸다. 실란 커플링제가 포함되지 않은 가황물의 가교밀도 변화가 실란 커플링제를 포함한 것에 비해 더 크게 나타났다. 실란 커플링제가 포함되지 않은 가황물의 경우에는 가교밀도의 변화에 대한 활성화 에너지가 가황촉진제의 함량이 증가할수록 순차적으로 낮아지는 경향을 보였다.

• 콘크리트학회논문집
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• 제25권3호
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• pp.331-338
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• 2013

최근 국가적 차원의 녹색성장이라는 패러다임 아래 건설분야에서도 자원과 에너지 절감을 위한 다양한 노력이 시도되고 있다. 이러한 방안의 하나로 단열성능이 향상된 콘크리트의 개발을 목적으로 높은 열저장 용량의 장점이 있는 PCM(phase change material)을 다공성의 경량골재에 함침 및 코팅 처리하여 경량골재 콘크리트를 개발하였으며 이를 평가하였다. 그 결과 흡수율이 높은 경량골재는 PCM 함침 및 코팅에 의해 흡수율이 저하되어 높은 흡수율에 따른 경량골재 콘크리트의 품질 저하를 방지하는 효과가 있음을 확인하였다. 또한 함침하지 않은 경량골재를 사용한 경량골재 콘크리트의 열전도율은 보통골재 콘크리트보다 약 33%의 단열성능 향상을 보였으며 함침된 골재의 경우 보통골재 콘크리트에 비해 40~43%의 단열성능 향상이 있는 것을 확인하였다. 또한 함침된 골재의 경우 비함침 골재에 비해 열전도율이 12~14% 정도 낮아지는 것을 확인 할 수 있었다.

• 한국의류산업학회지
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• 제22권6호
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• pp.853-861
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• 2020

Various types of clothing are being developed to boost thermal comfort during cold winters along with research on change of body temperature when heating is applied. There is a noticeable behavioral difference by gender when using heating panels in a cold environment; however, research on women has been insufficient. This study find a temperature range that provides sustainable thermal comfort in a low temperature environment by observing temperature and change of temperature when subjects are classified according to physical activities or cold sensitivities. For the study results, 8 women in their 20s were subjected to experiment in a low temperature environment for 75 minutes (sitting position: 30 min., running: 15 min., and sitting position: 30 min.). Subjects were asked to turn on/off the heating panel freely to analyze the range of comfortable temperature and clothing microclimate; in addition, skin temperature and heating panel temperature were measured and analyzed at 9 points. As a result, temperature at which subjects turn on and off the heating panel indicated a statistically meaningful difference between the cold sensitivity group depending on exercise or non-exercise. The range of comfortable abdomen temperature was wider than the lower back and was significantly reduced when the subject was running. The range of comfortable temperature was also largest for the heating panel temperature, microclimate, and skin temperature in suggesting that adequate adjustment will be required depending on the surrounding environment or movement of the wearer.

• 한국환경과학회지
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• 제21권1호
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• pp.69-81
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• 2012

This study forecasts changes in thermal environment and microclimate change per new building construction and assignment of green space in urban area using Computational Fluid Dynamics(CFD) simulation. The analysis studies temperature, humidity and wind speed changes in 4 different given conditions that each reflects; 1) new building construction; 2) no new building construction; 3) green spaces; and 4) no green spaces. Daily average wind speed change is studied to be; Case 2(2.3 m/s) > Case 3. The result of daily average temperate change are; Case 3($26.5^{\circ}C$) > Case 4($24.6^{\circ}C$) > Case 2($23.9^{\circ}C$). This result depicts average of $2.5^{\circ}C$ temperature rise post new building construction, and decrease of approximately $1.8^{\circ}C$ when green space is provided. Daily average absolute humidity change is analysed to be; Case 3(15.8 g/kg') > Case 4(14.1 g/kg') > Case 2(13.5 g/kg'). This also reveals that when no green spaces is provided, 2.3 g/kg' of humidity change occurs, and when green space is provided, 0.6 g/kg change occurnd 4(1.8 m/s), which leads to a conclusion that daily average wind velocity is reduced by 0.5 m/s per new building construction in a building complex.