• 한국세라믹학회지
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• 제54권4호
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• pp.314-322
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• 2017

This study investigates changes in the mechanical behavior, such as changes in indentation load-displacement curve, wear resistance and contact fatigue resistance of thermal barrier coatings (TBCs) by thermal cycling test and thermal shock test. Relatively dense and porous TBCs on nickel-based bondcoat/superalloy are prepared; the highest temperature applied during thermal durability test is $1350^{\circ}C$. The results indicate that the porous TBCs have relatively longer lifetime during thermal cycling and thermal shock tests, while denser TBCs have relatively higher wear and contact fatigue resistance. The mechanical behavior is influenced by sintering of the TBCs by exposure to high temperature during tests.

• 에너지공학
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• 제8권2호
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• pp.224-232
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• 1999

캡슐형 잠열재를 이용한 열저장 시스템은 바닥 난방 및 건물 난방에서 매우 효과적인 시스템이다. 이러한 시스템 개발에 필수적인 요소가 열유동 매체가 순환하는 파이프 주변의 캡슐내 온도 분포와 열유동 매체의 유량 등이다. 그러므로 본 연구에서는 3차원 비정상 상태에서 Navier-Stokes 방정식, 난류모델을 비롯한 스칼라 보존 방정식을 적용하여 캡슐 블록의 온도 분포 및 파이프 내의 유동장 해석을 수행하였다. 또한 본 연구와 같이 계산 영역이 특별한 기하학적 현상을 형상(circle+square)인 문제 해결하는데 적용할 수 있는 새로운 격자 생성 기술(MBFGE/CCM)을 개발하였다. 격자계는 파이프에서 원형 격자를 이용하였고, 캡슐 블록에서 사각 격자를 이용하여 다중격자와 미세격자를 결합하여 사용하였다. 본 연구의 목적은 컴퓨터를 이용한 수치해석적 방법을 미세 캡슐을 이용한 축열보드에 적용하여 2종류의 열경계 상태에 대하여 속도와 온도분포를 계산하여 비교분석을 하는 것이다. 온도는 축열 보드의 한 쪽면은 대류면이고 다른 한쪽면은 단열면인 경우(Case 2)보다 양면 모두 단열인 경우(Case 1)일 때 더 높게 상승하였다. 온수 파이프 중심선인 Y=0 에 가까운 영역에서 Case 1과 Case 2사이에 축열 보드 내에서 온도 차이는 확연하게 나타났다. 향후 수치해석의 정확도를 높이고 축열 보드의 열전달 현상을 보다 정확히 계산하기 위해서는 위치 및 시간에 따른 정밀한 온도 측정값이 필요하고 특히 잠열재인 미세 캡슐이 상변화를 하므로 온도 변화에 따른 물질의 비열(C$_{p}$)과 열전달율(λ)을 고려한 방정식이 요구된다.

• Journal of Acupuncture Research
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• 제17권3호
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• pp.219-232
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• 2000

Objective : The meridian and the acupuncture point of oriental medicine are very important in the department of acupuncture and moxibustion. Recently, we needed to study on the phenomenon of the meridian and acupuncture point with objective data. And then, I made a study of effects on the thermal changes of Five-shu-points(五輸穴) of the Lung meridian with acupuncture on Taeyon($L_9$, 太淵), using Digital infrared thermal imaging(D.I.T.I). Method : This study researched into clinical statistics for 60 men who are in good health. The objective was divided into two groups, one was the control group(CON, N=30) and the other was acupuncture group(ACU, N=30). The first, I took a picture for 60 men with the Digital infrared thermal imaging(D.I.T.I.). After 10 minutes, I took a second picture for each group following experimental methods. Results : I. The Mean temperature of Sasang($L_{11}$), Oje($L_{10}$), Taeyon($L_9$), Kyonggo($L_8$), Choldaek($L_5$) and Taenung($P_7$) area in adult men with good health, made a no significant difference with left and right side points. 2. Acupuncture group with acupuncture stimularion on Taeyon($L_9$) had a effect on much thermal changes of Sasang($L_{11}$), Oje($L_{10}$), Taeyon($L_9$), Kyonggo($L_8$) and Choldaek($L_5$) than control group. The thermal changes of the area which is a meridian point in the Lung Meridian of acupuncture group differed from control group with significant decrease and increase following the decreasing or increasing temperature class. Each class of ascent and descent thermal change was statistically significant value compared with control group. 3. Acupuncture group with acupuncture stimulation on Taeyon($L_9$) had not a effect on thermal changes of Taenung($P_7$) area than control group. And the increasing and decreasing temperature class of the acupuncture group did not significantly differ from control group. Conclusion : I could think that the acupuncture on Taeyon($L_9$) affected the thermal change of the area which is the Five-shu-points in the Lung Meridian. And then I could relate these results with the existence of the meridian and acupuncture point.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.789-794
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• 2002

The relationship is investigated between material modeling of concrete and the evaluation procedure of thermal stress by the hydration heat. In this respect, some important points are suggested to which special attention should be paid to reasonably evaluate the thermal stress using the widely-used structural analysis programs. This study indicates that proper material model should be used to draw incremental stress evaluation that takes into account the change of elastic modulus with time. Some correction techniques are also presented when using the program that don't have proper built-in procedure for the calculation of the thermal stress.

• 한국안전학회지
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• 제16권4호
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• pp.160-167
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• 2001

Cracking in connote structures is one of the main issues of structural design next to ensuring the load-bearing capacity. Thermal analysis is used to prevent thermal mucking, but concrete properties are uncertain variable, and analysis results have uncertainty, too. In this study, sensitivity analysis is performed to investigate the effect of conductivity, specific heal and pouring temperature. The results show that lower conductivity and higher specific heat increase the maximum temperature and maximum tensile stress. The structure with internal restraint is mostly influenced by the change of conductivity and specific heat.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1145-1150
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• 2000

Concrete behaves as ductile material at high temperature. The existing stress-strain relationship is not valid at high temperature condition. Thus, stress-strain curve of concrete at high temperature is re-established by modifying Saenz's suggestion in this study. A constitutive model of concrete subjected to elevated temperature is also suggested. The model consists of three components; free thermal stain, mechanical strain and thermal creep strain. As the temperature increase, the thermal creep becomes more critical to the failure of concrete. The thermal creep strain of concrete is derived from the modified power-law relation for the steady state creep. The proposed equation for thermal creep employs a Dorn's temperature compensated time theorem

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.146-148
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• 2005

This study investigates to detect sea surface temperature (SST) and land cover change after tide embankment construction using Landsat Thematic Mapper (TM) thermal infrared (TIR) band data at Shihwa Lake and surrounding area. SST measurement is important for studies of both the structure of the ocean and as the thermal boundary between the ocean and the atmosphere. The TIR band of TM images can be used to detect SST change whose shoreline is complicated and narrow like the study site. The purpose of this study is to estimate SST and land cover change at Shihwa Lake and surrounding area.

• 설비공학논문집
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• 제13권11호
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• pp.1097-1105
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• 2001

The purpose of this study is to investigate the propriety of TMA clathrate as a cold storage medium. Particularly, this is to examine the extent of subcooling improvement when the additives are added to the TMA clathrate, because water used cold storage material has low phase change temperature and subcooling. This study has been analysed and compared with TMA 30 wt% clathrate how phase change temperature, subcooling and specific heat in the various concentrations are changed. This results view to be improved phase change temperature and subcooling of TMA 30 wt% as a cold storage medium, when it had some additive. Additional1y, it is found that the additive must be controlled under available solution limit and study for new additive must be lasted to know its effect.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권1호
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• pp.32-39
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• 2003

Though conventional calorimetry methods such as differential scanning calorimetry and differential thermal analysis are used generally in measuring heat of fusion, T-history method has advantages of a simple experimental apparatus and no requirements of sampling process, which is particularly useful for measuring thermophyical properties of in-homogeneous phase change materials in sealed tubes. However, the degree of supercooling used in selecting a range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion. In the present study, it was shown that a 40% discrepancy exists between the original T-history and the present methods when analyzing the same experimental data. As a result, a reasonable modification to the original T-history method is proposed.

• 전기학회논문지
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• 제60권12호
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• pp.2311-2317
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• 2011

In this paper, we study the temperature change of a ${\mu}$-bolometer focal plane array with a capacitive transimpedance amplifier bias cancellation circuit. Thermal analysis is essential to understand the performance of a ${\mu}$-bolometer focal plane array, and to improve the temperature stability of a focal plane array characteristics. In this study, the thermal analyses of a ${\mu}$-bolometer and its two reference detectors are carried out as a function of time. The analyses are done with the $30{\mu}m$ pitch $320{\times}240$ focal plane array operating of 60 Hz frame rate and having a columnwise readout. From the results, the temperature increase of a ${\mu}$-bolometer in FPA by an incident IR is estimated as $0.689^{\circ}C$, while the temperature increase by a pulsed bias as $7.1^{\circ}C$, which is about 10 times larger than by IR. The temperature increase of a reference detector by a train of bias pulses may be increased much higher than that of an active ${\mu}$-bolometer. The suppression of temperature increase in a reference bolometer can be done by increasing the thermal conductivity of the reference bolometer, in which the selection of thermal conductivity also determines the range of CTIA output voltage.