• Journal of Radiation Industry
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• v.8 no.1
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• pp.17-22
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• 2014

In this study, we prepared CdTe/CdS solar cells using a thermal vacuum evaporation method. In particular, $CdCl_2$ treatment was attempted using this same method at $400^{\circ}C$ for 30 min. The prepared CdTe/CdS solar cells were investigated using Fouier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FE-SEM), and a solar simulator system including light absorption properties, morphological properties, and power conversion efficiency (PCE). In addition, we investigated the gamma-irradiation treatment at dose rates of 0 Gy, 500 Gy, 1 kGy, 10 kGy, and 30 kGy. The characteristics of gamma-irradiation treatment were studied based on the same method described above. In particular, it showed increased values as 0.826% higher than the non-irradiation of 0.448% from PCE analysis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.1
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• pp.28-34
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• 2016

Far-infrared radiation ceramic is an attractive material that provides thermal therapy by permeating the infrared rays into the deep inside of the human skin. Therefore, it is currently used for thermal therapy devices, thermal mat, heating equipment and so on. This work aims to optimize the sintering process of the far-infrared radiation ceramic with the process parameters of temperature and time. A variety of characterization tools have been used to investigate the optimal sintering condition of far-infrared radiation. The phase of far-infrared radiation ceramic was characterized by using X-ray diffraction (XRD) and microstructure of fracture surface was studied by scanning electron microscopy (SEM). The FT-IR was also performed to measure the far-infrared emissivity.

• Journal of computational fluids engineering
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• v.19 no.1
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• pp.1-6
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• 2014

Since experiments on the actual operational status are said to be very impractical because of their economic and repeatability problems, it is difficult to understand the thermal profiles of aerospace or military equipments. Thus, the CFD codes with considering the radiation heat transfer are used to compensate the defect. In case, analyzing the radiation exchanges between the object surfaces are very important. Because the temperature and the IR signal distributions of the object surface are significantly affected by the radiative heat transfer. To achieve accurate thermal radiation exchange between surfaces, it is important to calculate the radiation view factor precisely. Finer subdivision of meshes can be used to increase the accuracy of radiation view factor, but if the mesh is subdivided infinitely, the time required for calculation increases significantly and thus decreasing the efficiency. If the subdivision is not sufficient, assurance of accuracy is not guaranteed. In this paper, optimal mesh subdivision method using the solid angle has been successfully tested and found to be useful in increasing the efficiency of calculating the shape factors.

• Geomechanics and Engineering
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• v.15 no.5
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• pp.1125-1133
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• 2018

Real-time characterization of the rock thermal deformation and fracture process provides guidance for detecting and evaluating thermal stability of rocks. In this paper, time -frequency characteristics of acoustic emission (AE) and electromagnetic radiation (EMR) signals were studied by conducting experiments during rock continuous heating. The coupling correlation between AE and EMR during rock thermal deformation and failure was analyzed, and the microcosmic mechanism of AE and EMR was theoretically analyzed. During rock continuous heating process, rocks simultaneously produce significant AE and EMR signals. These AE and EMR signals are, however, not completely synchronized, with the AE signals showing obvious fluctuation and the EMR signals increasing gradually. The sliding friction between the cracks is the main mechanism of EMR during the rock thermal deformation and fracture, and the AE is produced while the thermal cracks expanding. Both the EMR and AE monitoring methods can be applied to evaluate the thermal stability of rock in underground mines, although the mechanisms by which these signals generated are different.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.184-189
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• 2008

The excess heat that is generated from PV modules can be removed and converted into useful thermal energy. A photovoltaic/thermal(PVT) module is a combination of photovoltaic module with a solar thermal collector, forming one device that converts solar radiation into electricity and heat simultaneously In general, two types of PVT can be distinguished: glass-covered PVT module, which produces high-temperature heat but has a slightly lower electrical yield, and uncovered PVT module, which produces relatively low-temperature heat but has a somewhat higher electrical performance. In this paper, the experimental performance of water type unglazed PVT combined module, analyzed. The electrical and thermal performance of the module were measured in outdoor conditions, and the results are analyzed. The results showed that the thermal efficiency of the PVT module was 27.05% average and its PV efficiency was about 11.85% average, both depending on solar radiation, inlet water temperature and ambient temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.260-265
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• 2008

The excess heat that is generated from PV modules can be removed and converted into useful thermal energy. A photovoltaic/thermal (PVT) module is a combination of photovoltaic module with a solar thermal collector, forming one device that converts solar radiation into electricity and heat simultaneously. In general, two types of PVT can be distinguished : glass-covered PVT module, which produces high-temperature heat but has a slightly lower electrical yield, and uncovered PVT module, which produces relatively low-temperature heat but has a somewhat higher electrical performance. In this paper, the experimental performance of water type PVT combined module, glass-covered, analyzed. The electrical and thermal performance of the module were measured in outdoor conditions, and the results are analyzed. The results showed that the thermal efficiency of the PVT module was 27.6% average and its PV efficiency was about 10.0% average, both depending on solar radiation, inlet water temperature and ambient temperature.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.644-653
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• 2019

With the development of themal observatory device(TOD), thermal camouflage system has been applied not only to the weapon system but also to the combat suit for soldiers. In this paper, the characteristic of thermal radiation of human body depending on the clothing material properties was analyzed through numerical simulations. The bioheat equation with thermoregulatory model was solved to obtain the realistic surface temperature of human body and these results are combined with the emissivity of human skin and clothing in order to calculate the thermal signature from the human body. According to each thermal resistance of clothing, the optimal background radiance which makes contrast radiance intensity(CRI) be lowest is different. Also, the average CRI variation per thermal resistance change is about twice as much as the case of evaporative resistance change.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2360-2365
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• 2007

A new microemitter (microcombustor) configuration for a micro thermophotovoltaic system in which thermal energy is directly converted into electrical energy through thermal radiation was investigated experimentally and computationally. The microemitter as a thermal heat source was designed for a few watt power-generating micro thermophotovoltaic system. In order to satisfy the primary requirements for designing the microemitter, i.e., stable burning in the small confinement and maximum heat transfer through the emitting walls but uniform distribution of temperature along the walls, the present microemitter is cylindrical with an annular-type shield for heat recirculation to apply for the excessive enthalpy concept. Results show that the heat recirculation substantially improves the performance of the microemitter: the observed and predicted thermal radiation from the microemitter walls indicated that heat generated in the microemitter is uniformly emitted.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2620-2629
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• 2020

As an early stage in the development of a water calorimeter, this study established a computer simulation methodology for analyzing the thermal behavior of a water calorimeter based on radiation transport and energy deposition. As a result, this study developed a method wherein the energy deposition distribution, which is obtained by applying Monte Carlo methods in water calorimeters, is directly used as a heat source for the thermal analysis model. Based on the proposed method, heat transfer in a water vessel and the effect of thermistor self-heating were analyzed. Through an analysis of the water velocities with and without a water vessel, it was found that a water vessel can serve as a convection barrier. Furthermore, it was confirmed that when considering thermistor self-heating, the water temperature change at the thermistor location is 0.219 mK higher compared to that when the thermistor was not considered. Therefore, thermistor self-heating must be considered to analyze the thermal behavior of a water calorimeter more accurately.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2574-2581
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• 1993

A Shadow mask in C. R. T. (Cathod Ray Tube) undergoes a temperature increase due to impinging electron beams emitted from guns, and thermal deformation from such temperature rise may cause the electron beams to island on the panel, and thus give rise to depolarization. Hence the analysis of temperature distribution for a shadow mask is an important procedure for designing the shadow mask. In this paper, we are concerned with nonlinear finite element analysis of the temperature distribution on a shadow mask. First of all, we replace shadow mask, containing numerous apertures of a slit type, by an orthotropic shell without apertures, and calculate the apparent thermal conductivities. Because of thermal radiation, which is one of the major heat transfer mechanism for shadow masks, the resulting finite element equation is nonlinear and solved by the Newton method. Finally numerical examples are illustrated for a 21" FST(Full Square Tube) shadow mask, and followed by discussion.sion.