• 대한설비공학회지:설비저널
• /
• 제11권3호
• /
• pp.9-17
• /
• 1982

In this paper, temperature distributions in radial fin of hyperbolic profile for steady -state with no heat generation are obtained by one-dimensional analytical method, finite difference method and experiment respectively. Heat flow rate and fin efficiency from the fin model are obtained by analytical method. To compare the exact solutions obtained by theoretical analysis with the results obtained by finite difference method, cylindrical shape is selected. Particularly, equations of finite difference method for cylindrical shape with irregular boundary are rearranged and formulated. Consequently, temperature distributions in radial fin can certify that are similar to exact solutions. From theoretical analysis, the effects according to heat flow rate and fin efficiency are related to variation of parameters which are fin thickness ${\delta}_o$, fin base temperature $T_o$, thermal conductivity K with same basic dimensions and the fleets are studied and compared.

• 대한기계학회논문집
• /
• 제12권5호
• /
• pp.952-958
• /
• 1988

본 연구에서는 폭방향 불균일 냉각에 따른 열응력이 판변형 및 잔류응력의 주 요원인이라는 고려하에 냉각중에 압연판의 온도분포 및 열응력을 예측할 수 있는 수치 해석 모델을 구성하였다. 온도와 응력 계산에 상변태 현상을 고려하였으며, 판변형 은 압축성분 열응력에 의한 좌굴현상으로 고려하여 해석하였다.

• Journal of Biosystems Engineering
• /
• 제21권4호
• /
• pp.436-448
• /
• 1996

An earth tube soil air heat exchange system was designed, installed and operated as a single pass heat exchanger to utilize the geothermal energy as an natural energy source. This study was undertaken to investigate the potential of the heating and cooling, energy gain, heat exchange efficiency and coefficient of performance of the system. The system consisted of 30m in length and 30cm in diameter polyethylene pipes buried 2m deep in soil. Maximum heating and cooling performance were 2.51㎾ and 1.26㎾ at the air mass rate of 21cmm. Energy gain and coefficient of performance were the function of temperature difference between outside air and soil temperature. They were expressed as Q=0.33$ imes$$Delta T_{max}$+0.134(㎾) for energy gain and COP=0.44$ imes$$Delta T_{max}$+0.178 for coefficient of performance with correlation factor of 0.95. The mean of heat exchange efficiencies was 85.6%.

• 동력기계공학회지
• /
• 제11권3호
• /
• pp.35-40
• /
• 2007

Leak would happen because of the damage of high temperature and high-pressure valve in nuclear power plant. condition based prevention maintenance is essential by using the suitable method based on local condition. Energy loss prevention can prevent from an accurate test, Local actually and ability. The methods of test for high energy fluid leak at present are analysis of ${\Delta}T$, AE(Acoustic Emission) analysis, and thermal image. The result for test of secondary system in nuclear power plant Unit reveals that the AE occurred clearly in leakage situation, but thermal image didn't occur. It is identified that leak is occurred when the orifice located front and back of valve operates. It shows that making a impatient judgment by using the single method if it is leakage is containing uncertainty. So we think that using the Multi-Measuring method is more sound judgment than single-measuring method.

• 대한한방체열의학회지
• /
• 제6권1호
• /
• pp.8-15
• /
• 2008

Purpose: Although premsnstrual syndromes(PMS) have long been recognized, there has been difficulty to evaluate the symtoms. Usually the questionnaire has been used to dignose the PMS. Objective is to investigate the relationship of body temperature between women with PMS and without PMS. Methods: We studied 23 patients visiting OO hospital from 26th December 2005 to 26th April 2006. The Questionnaire for PMS was used to evaluate physical, emotional, and behavioral symptoms accompanying the menstrual cycle of the subjects. The subjects were categorized in two groups, non-PMS(11) and PMS group(12). Body temperature was assessed by Dorex spectrum 9000MB (DOREX Inc., USA). We measured CV4, CV3, CV12 and CV17 to evaluate the distribution of body temperature, compared the difference of temperature(${\Delta}T$) between CV17-CV4, CV17-CV3, CV17-CV12 and CV12-CV3. We investigated the of temperature and ${\Delta}T$ between two groups by Mann-Whitney U-test. Results: The temperature of CV3 and CV4 of PMS located in low abdomen were lower than those of non-PMS located in chest. But there was no statistical significance of temperature between two groups. There was lower temperature of low abdomen in PMS group than non-PMS group without statistical significance. Conclusion: The results suggest that DITI could be useful to assess the PMS objectively. But more research should be needed.

• 대한한방부인과학회지
• /
• 제21권3호
• /
• pp.111-120
• /
• 2008

Purpose: Although premsnstrual syndromes(PMS) have long been recognized, there has been difficulty to evaluate the symtoms. Usually the questionnaire has been used to dignose the PMS. Objective is to investigate the relationship of body temperature between women with PMS and without PMS. Methods: We studied 23 patients visiting ㅇㅇ hospital from 26th December 2005 to 26th April 2006. The Questionnaire for PMS was used to evaluate physical, emotional, and behavioral symptoms accompanying the menstrual cycle of the subjects. The subjects were categorized in two groups, non-PMS(11) and PMS group(12). Body temperature was assessed by Dorex spectrum 9000MB (DOREX Inc.. USA). We measured CV4, CV3, CV12 and CV17 to evaluate the distribution of body temperature, compared the difference of temperature(${\Delta}T$) between CV17-CV4, CV17-CV3, CV17-CV12 and CV12-CV3. We investigated the of temperature and ${\Delta}T$ between two groups by Mann-Whitney U-test. Results: The temperature of CV3 and CV 4 of PMS located in low abdomen were lower than those of non-PMS located in chest. But there was no statistical significance of temperature between two groups. There was lower temperature of low abdomen in PMS group than non-PMS group without statistical significance. Conclusion: The results suggest that DITI could be useful to assess the PMS objectively. But more research should be needed.

• 한국대기환경학회지
• /
• 제12권4호
• /
• pp.369-376
• /
• 1996

Major atmospheric stability classification methods were evaluated with meteorological data obtained by scoustic sounding profiler (SODAR/RASS) in Seoul. The Psequill classificatio method, the method most widely used because of its good agreement in respect of synoptic scope under the steady state, fails to describe the time lag, the response time on stability by heating or cooling caused by daily insolation or noctrunal surface radiation. Horizontal and vertical standard deviation of wind fluctuation $(\sigma_A and \sigma_E)$ method tend to classify night-time stable condition (E, F class) into unstable condition (A, B class). The classification matrix tables for Vogt's vertical temperature difference and wind speed using method ($\Delta$T $\cdot$ U) and bulk Richardson number (Rb) were amended for practical use over Seoul. The modified tables for $\Delta$T $\cdot$ U and Rb method were made by using comprehensive frequency distribution from Pasquill's method and other existing results, and the correlation coefficient(r) was equal to 0.829. It was confirmed that atmospheric stability could be changed with monitoring site characteristics, height and vertical difference between sensors of monitoring station, and classification method itself.

• 한국결정성장학회지
• /
• 제19권3호
• /
• pp.116-124
• /
• 2009

Our computational studies for the physical vapor transport crystal growth of $Hg_2Cl_2-Cl_2$ system evidence suggests that the PVT growth process exhibits the diffusion-dominated behaviors for aspect ratios more than and equal to 10, which would provide purely diffusive transport conditions adequate to microgravity environments less than $10^{-3}g_0$. Also, the regimes of high temperature difference based on the fixed source temperature of $380^{\circ}C$, where ${\Delta}T$ is relatively large enough for the crystal growth of mercurous chloride, the transport rates do not keep increasing with ${\Delta}T$ but tend to some constant value of $2.12\;mole\;cm^{-2}s^{-1}$. For the aspect ratios of 5, 10, and 20, the transport rate is directly proportional to the total pressure of the system under consideration. For Ar = 5, the rate is increased by a factor of 2.3 with increasing the total pressure from 403 Torr to 935 Torr, i.e., by a factor of 2.3. For both Ar = 10 and 20, the rate is increased by a factor of 1.25 with increasing the total pressure from 403 Torr to 935 Torr.

• 마이크로전자및패키징학회지
• /
• 제25권3호
• /
• pp.67-74
• /
• 2018

두께 $2.5{\sim}10{\mu}m$인 n형 $Bi_2Te_3$와 p형 $Sb_2Te_3$ 레그 8쌍으로 구성되어 있는 in-plane형 열전박막소자를 전기도금법으로 Si submounts에 형성하고, LED 칩의 구동에 의해 발생하는 겉보기 온도차 ${\Delta}T$와 레그 두께에 따른 발전특성을 분석하였다. LED 방출열에 의해 인가된 ${\Delta}T$가 7.4K일 때 각기 두께 $2.5{\mu}m$, $5{\mu}m$ 및 $10{\mu}m$의 p-n 레그들로 구성된 열전박막소자는 6.1 mV, 7.4 mV 및 11.8 mV의 open circuit 전압을 나타내었으며, 6.6 nW, 12.8 nW 및 41.9 nW의 최대 출력전력을 나타내었다.

• 열처리공학회지
• /
• 제8권2호
• /
• pp.120-126
• /
• 1995

The effects of heating rate on the combustion temperature, the ignition temperature, the microstrurcture and the shape memory ability of products formed by combustion were investigated. The ignition temperature decreased with increasing heating rate. Combustion temperature and ${\Delta}T$(difference temperature between the ignition temperature and the combustion temperature) increased with increasing heating rate. The grain size of the product increased with increasing heating rate. Combustion synthesis did not completely occur below the heating rate of $10^{\circ}C/min$. NiTi intermetallic compound was completely formed at the heating rate of $600^{\circ}C/min$ and the product by combustion method had a good shape memory effect.