• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.146-147
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• 2009

$CuGaSe_2$ (CGS) layers were grown by the hot wall epitaxy method. The optimum temperatures of the substrate and source for growth turned out to be 450 and $610^{\circ}C$, respectively. Based on the absorption measurement, the band-gap variation of CGS was well interpreted by the Varshni's equation. By analyzing these emissions, a band diagram of the observed optical transitions was obtained. From the solar cell measurement, an 11.17 % efficiency on the n-CdS/p-CGS junction was achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.86-87
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• 2009

High quality $CuInSe_2$ (CIS) were grown on GaAs substrate by using the hot wall epitaxy method. The behavior of point defects in the CIS layer investigated by using photoluminescence (PL) at 10 K. Point defects originating from $V_{Cu}$, $V_{Se}$, $Cu_{int}$, and $Se_{int}$ were classified as donor or acceptor types. These PL results also led us to confirm that the p-type CIS layer had obviously converted into n-type after the Cu atmosphere treatment. Finally, we found that the In in the CIS layer did not form the native defects, because In existed in the form of stable bonds in the CIS layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.377-377
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• 2010

The $AgInS_2$ epilayers with chalcopyrite structure grown by using a hot-wall epitaxy (HWE) method have been confirmed to be a high quality crystal. After the as-grown $AgInS_2$/GaAS was annealed in Ag-, S-, and In-atmosphere, the origin of point defects of the $AgInS_2$/GaAs has been investigated by using the photoluminescence (PL) at 10 K. The native defects of $V_{Ag}$, $V_s$, $Ag_{int}$, and $S_{int}$ obtained from PL measurement were classified to donors or acceptors type

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.409-424
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• 1987

Simulation on the hot water ONDOL heating system was made in order to investigate the variation of room temperature and specific fuel consumption of boiler. Heat balance equation was derived by response factors and solved implicitly. Variation of room temperature and specific fuel consumption of boiler were calculated with respect to the thickness of room floor, the absorptivity of wall for solar radiation, on-off temperature range of boiler and air exchange. The results show that specific fuel consumption of boiler is independent of the thickness of room floor and decreases with increasing the absorptivity of wall and on-off temperature range of boiler. However, it increases with increasing the air exchange. They also show that, when the absorptivity and on-off temperature range of boiler are increased, the amplitudes of room temperature variation increase.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.543-552
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• 2003

The effects of a directionally emitting and reflecting dielectric surface on the wall heat flux and medium temperature distribution are studied. The system is an infinite square duct enclosing an absorbing and emitting medium. The emissivity and reflectivity of opaque and gray wall vary with direction. Combined effect of conductive and radiative heat transfer is analyzed using finite difference and the direct discrete-ordinates method. The parameters under study are conduction to radiation parameter, optical depth, refractive index ratio. The results with directional and diffuse properties deviate each other when the conduction to radiation parameter is less than around 0.01. The wall heat flux differs fur optical thickness less than around 0.1. However, the medium temperature profiles differ for optical thickness greater than around 1. Deviations from diffuse property calculations are larger for hot wall with directional property than cold wall with directional property. As n increases from 1.5, the trend changes are observed fur refractive index ratio about n=6.10

• Journal of the Korean Home Economics Association
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• v.39 no.4
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• pp.49-59
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• 2001

Natural red and yellow dyestuff was extracted from safflower (Carthamus tinctorius Linnaeus) by a new process of cellulase extraction compared with the conventional hot water extraction. Dyestuffs were extracted from safflower easily and repeatedly by means of cellulose as safflower cell wall destroyer. It means that new dyestuff extraction by cellulase improves not only yields of dyestuff from safflower successfully but also the rate of repetition of extraction. From the above experiments, the conclusions of this study were summarized as follows. 1. The optimum conditions of dyestuff extraction from safflower by general extraction method were that the solvent was the water of pH 6.0 on yellow dyestuff and 3% $K_2CO_3$ solution on red dyestuff, extraction temperature was $55^{\circ}C$, and extraction time was 30 min. 2. Among various cellulase, the NOVO cellulase was the best cell wall destroyer of safflower and finally produced the largest amount of dyestuff from safflower by cellulase extraction method. 3. The optimum conditions of dyestuff extraction by cellulase extraction method were conducted on 10 unit of cellulase per gram of safflower at $100m{\ell}$ water of pH 5.0 at $50^{\circ}C$ for 30 min.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.344-348
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• 2004

The CdSe thin films wee grown on the Si(100) wafers by a hot wall epitaxy method(HWE). The source and substrate temperature are $600^{\circ}C\;and\;430^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by van der Pauw method and studied on the carrier density and mobility dependence on temperature. From Hall data, the mobility was increased in the timperature range 30K to 150K by impurity scatering and decreased in the temperature range 150K to 293K by the lattice scattering. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.39{\times}10^7$, the MAPD of 335mV, and the rise and decay time of 10ms and 9.5ms, respectively

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.304-308
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• 2004

The $Cd_{1-x}Zn_xS$ thin films were grown on the Si(100) wafers by a hot wall epitaxy method(HWE). The source and substrate temperature are $600^{\circ}C\;and\;440^{\circ}C$ respectively. The crystalline structure of epilayers was investigated by double crystal X-ray diffraction(DCXD). Hall effect on the sample was measured by the van der Pauw method and studied on the carrier density and mobility dependence on temperature. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to darkcurrent(pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time. The results indicated that the photoconductive characteristic were the best for the $Cd_{0.53}Zn_{0.47}S$ samples annealed in Cu vapor compare with in Cd, Se, air and vacuum vapour. Then we obtained the sensitivity of 0.99, the value of pc/dc of $1.65{\times}10^7$, the MAPD of 338mW, and the rise and decay time of 9.7ms and 9.3ms, respectively

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.2
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• pp.149-157
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• 2008

During CVD process of semiconductor wafer fabrication, maintaining the uniformity of temperature distribution at wafer top surface is one of the key factors affecting the quality of final products. Effect of contact conductance between wafer and hot plate on predicted temperature of wafer was investigated. The validity of opaque wafer assumption was also examined by comparing the predicted results with Discrete Ordinate solutions accounting for semitransparent radiative characteristics of silicon. As the contact conductance increases predicted wafer temperature increases and the differences between maximum and minimum temperatures within wafer and between wafer and hot plate top surface temperatures decrease. The opaque assumption always overpredicted the wafer temperature compared to semitransparent calculation. The influences of surrounding reactor inner wall temperature and hot plate configuration are then discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.175-178
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• 2004

The stochiometric mixture of evaporating materials for the $ZnIn_2S_4$ single crystal thin film was prepared from horizontal furnace. To obtain the $ZnIn_2S_4$ single crystal thin film, $ZnIn_2S_4$ mixed crystal was deposited on throughly etched semi-insulating GaAs(100) in the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were $610^{\circ}C$ and $450^{\circ}C$, respectively and the growth rate of the $ZnIn_2S_4$ sing1e crystal thin film was about $0.5\;{\mu}m/hr$. The crystalline structure of $ZnIn_2S_4$ single crystal thin film was investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of $ZnIn_2S_4$ single crystal thin film measured from Hall effect by van der Pauw method are $8.51{\times}10^{17}\;cm^{-3}$, $291\;cm^2/V{\cdot}s$ at $293_{\circ}\;K$, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $ZnIn_2S_4$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}S_O$ and the crystal field splitting ${\Delta}Cr$ were 0.0148 eV and 0.1678 eV at $10_{\circ}\; K$, respectively. From the photoluminescence measurement of $ZnIn_2S_4$ single crystal thin film, we observed free excition $(E_X)$ typically observed only in high quality crystal and neutral donor bound exciton $(D^{o},X)$ having very strong peak intensity The full width at half maximum and binding energy of neutral donor bound excition were 9 meV and 26 meV, respectively, The activation energy of impurity measured by Haynes rule was 130 meV.