• Korean Chemical Engineering Research
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• 제59권1호
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• pp.77-84
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• 2021

Plug flow reactor (PFR) 내의 과열점(hot spot) 온도를 조절하는 것은 생성물의 수득률 및 순도, 안전성 측면에서 중요하다. 본 연구에서는 더 현실에 가깝게 모델링 하기 위하여 PFR 내부의 냉각액 온도를 상태변수로 설정하고 방사 방향의 열 및 물질전달을 고려하였다. 모델은 반응물의 농도 및 온도와 냉각액의 온도 총 3개의 상태변수로 이루어져 있으며, 등온 냉각액의 유량을 조작변수로 가진다. 본 연구에서는 방사 방향의 열 및 물질전달을 고려한 제어식이 그렇지 않은 제어식보다 과열점의 온도를 set point 부근으로 더 효과적으로 유지한다는 것을 보였다. 본 연구에서 제안한 제어식은 냉각액의 온도가 반응물 온도의 약 0.7배 부근일 때 St가 1.3 이상이고 Ac/A가 2.0 이하인 조건에서 강건성을 유지하였다. 이 조건에서 반응기로 유입되는 반응물의 온도가 5% 범위에서 바뀔 때 본 연구에서 제안된 제안식을 이용하면 과열점의 온도를 set point의 1% 이내로 유지할 수 있다.

• 전기학회논문지P
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• 제63권4호
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• pp.327-332
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• 2014

In this paper, the temperature distribution according to the property change of the insulating oil of the power transformer and max temperature were predicted through the ductility interpretation which heat-flow is coupled. By using CFD (Computation Fluid Dynamics) for the interpretation, the temperature distribution of 154kV the class single phase power transformer was predicted. The power loss causing the temperature rise of the transformer was changed to the heat source and we used as the input value for the heat-flow analysis. The temperature distribution was predicted according to the change of the density, specific heat, thermal conductivity and viscosity, that is the ingredient having an effect on the temperature rise of the transformer oil. The mineral oil of 4 kinds used in domestic and international based on the interpreted result was selected and the temperature distribution according to each load and Hot Spot temperature was predicted.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.18-23
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• 2012

We propose and implement a single-wire communication protocol for thermal management systems using thin film thermoelectric modules for 3D IC cooling. The proposed single-wire communication protocol connects the temperature sensors, located near hot spots, to measure the local temperature of the chip. A unique ID number identifying the location of each hot spot is assigned to each temperature sensor. The prototype chip was fabricated by a $0.13{\mu}m$ CMOS MPW process, and the operation of the chip is verified.

• 전기학회논문지P
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• 제62권1호
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• pp.6-11
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• 2013

In this paper, the temperature characteristics of mold transformer for the distribution power system have been analyzed by using computational fluid dynamics(CFD). The model has been modeled by coil, cores, insulating materials and frames about 3MVA grade mold transformer and analyzed the temperature distribution of the structure with a heat fluid. The fluid, which is incompressible ideal gas, is analyzed as a turbulent flow phenomenon on the assumption that it is natural cooling of transformer cooling system. Through this study, by examining the temperature distribution and hot-spot of the structure field of the mold transformer, cooling design and temperature distribution information, which are demanded for designing are estimated.

• 한국초전도ㆍ저온공학회논문지
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• 제7권4호
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• pp.14-19
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• 2005

A transient numerical simulation was conducted to have variation of temperature on an element of resistive Superconducting Fault Current Limiter (SFCL) under quench condition. It is very important engineering information for an optimum design of cryogenic system for cooling of a resistive SFCL element. A bifilar coil for resistive SFCL for 10 MVA system was incorporated as a model in this numerical study. From the numerical simulation result, it was found that the averaged temperature on the shunt and Bi-2212 element at 500 kW, 100 ms was 711.1 K and 198.4 K respectively. The temperature variation with the change of the hot-spot size and time is also obtained. The maximum temperature was continuously increased in all cases until the hot-spot stops at 100ms and it was going down after then. Such as, the details of temperature distribution on the SFCL element obtained from this numerical study and it should be very valuable information on the decision of the cooling capacity of cryogenic system.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.211-218
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• 2000

Hot spot behaviors on the disk-pad contact surface during a braking operation have been analyzed for a ventilated disk brake using the finite element method. Hot spots which were studied using a coupled thermal-mechanical analysis technique are influenced by all of the mechanical, thermal, elastic and plastic processes that are involved in braking cycles, but their temperature gradients are most affected by rubbing speeds, braking forces, and design parameters between the disk and the pad. Undesirable hot spots that are generated by local thermoelastic instabilities are intended to be removed by optimized design parameters and material properties. In this study, a three-dimensional numerical method for the demonstration of hot spot behaviors has been applied to the rubbing surfaces between the disk and the pad.

• 대한수의학회지
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• 제42권2호
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• pp.269-275
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• 2002

The aim of this study was to investigate the usefulness and effectiveness of thermography in horse. Total 21 horses associated with locomotors, wound, and ophthalmic disease were investigated. Thermographically, the wannest area in normal limb was coronary band ($27.26^{\circ}C$), and carpus, metacarpus, fetlock, and pastern area were $26.64^{\circ}C$, $24.42^{\circ}C$, $23.64^{\circ}C$ and $23.06^{\circ}C$, respectively. The temperature($^{\circ}C$) of horses with lameness, swelling, nervous, ataxia was lower(cold spot) than surrounding tissue or symmetry area, and with heat, signs of inflammation was increased(hot spot). These results suggest that the thermography is useful for the early detection of locomotors, wound, and ophthalmic disease in horse and an excellent adjunct to clinical examination.

• 전기학회논문지P
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• 제64권4호
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• pp.256-260
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• 2015

In this paper, achieved rise temperature distribution about degradation phenomenon of 24 MVA distribution cast resin transformer using CFD(Computational Fluid Dynamics). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage(HV) winding and low-voltage(LV) winding of cast resin transformer and Joule's loss of core for improvement these life, forecasted heat source, and HV winding and LV winding of cast transformer rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the results. Also, calculated temperature rise limit of cast resin transformer and permission maximum temperature using analysis by electromagnetic heat source. Calculated and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

• 전자공학회논문지T
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• 제36T권2호
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• pp.70-76
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• 1999

최근에 휴대전화기가 저 연령층까지 널리 보급되어 어린이들의 두부내에 열점(hot-spot)형성문제가 염려되고 있는 실정이다. 전자파의 인체영향이 체온상승의 열적작용에 의한 것이라고 생각한다면 휴대전화기에 의해 발생하는 두부내 국소SAR의 인체영향도 두부의 온도상승과 연관된다고 추정된다. 본 논문은 휴대전화기를 실사용 상황에서 시간대별 두부의 국소부위에 대한 온도변화를 측정하였다. 그 결과 휴대전화기의 통화시작점에서 계속적인 온도상승을 보이다가 통화가 끝나는 시점에서 두부의 국소적인 온도변화는 빠르게 회복되지만 생체전신의 평균온도는 상승함을 알 수 있었다.

• 한국산업융합학회 논문집
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• 제5권4호
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• pp.321-327
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• 2002

There has been an increase in the public concern about possible health risks by electromagnetic exposure from mobile phones. Recently, increase in the use among young children of portable telephones public concern regarding potential health hazards due to a hot spot appearing inside the infant head, has been growing. Since the biological hazards due to RF exposure are caused mainly by a temperature-rise in tissue, the effect of localized SAR for portable telephones should also be related to the temperature-rise in the human head. In this paper, it was measured that in the actual use of portable telephone the temperature of the local tissue in the human-head change. As a result, it should be noted that the mean temperature of human-body and localized tissue is rising from beginning call. However the temperature variation of localized tissue is recovered rapidly as normal temperature, although the mean temperature of human-body rising continuously at ending call of portable telephone.