• 한국환경보건학회지
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• 제21권1호
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• pp.86-92
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• 1995

This study was performed to evaluate the effect of temperature on operating parameters for reactor in pig wastewater treatment using sequencing batch reactor method which is one of the biological treatment methods. Study was accomplished by experimental apparatus of bench scale, and the degradation rate coefficient and temperature correction factor were derived. The followings are the conclusions that were derived from this study. 1. In the characteristics of pig wastewater, concentrations of TKN and T-P were very high as 590 mg/l and 40 mg/l, respectively. 2. Removal efficiency of BOD and $COD_{Mn}$ as organic compound indicators were the highest mark as 97% at 25$\circ$C. 3. When temperature was incresed from 10$\circ$C to 25$\circ$C, removal efficiencies of TKN and T-P were proportionally increased. Especially, the former was greatly effected by temperature of reactor. 4. In experiment of bench scale, the degradation rate coefficients were increased as temperature increased, but decreased at the temperature range of 25~35$\circ$C. Temperature adjustment coefficients for $COD_{Mn}$, BOD, TKN and T-P were 1.1460, 1.1356, 1.1140 and 1.0565, respectively.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.144-149
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• 2022

A cryogenic Mixed Refrigerant Joule-Thomson refrigeration cycle was designed to be applied to the semiconductor etching process with non-flammable constituents. 3-stage cascade refrigerator, single mixed refrigerant Joule-Thomson refrigerator, and 2-stage cascade type mixed refrigerant Joule-Thomson refrigerator are analyzed to figure out the coefficient of performance. Non-flammable mixture of argon(Ar), tetrafluoromethane(R14), trifluoromethane (R23) and octafluoropropane(R218) were utilized to analyze the refrigeration cycle efficiency. The designed refrigeration cycle was adapted to cool down the coolant of HFE7200(Ethoxy-nonafluorobutane, C₄F₉OC₂H₅) with certain constraints. Maximum coefficient of performance of the refrigeration system is obtained as 0.289 for the cooling temperature lower than -100℃. The detailed result of the coefficient of performance according to the mixture composition is discussed in this study.

• 설비공학논문집
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• 제29권10호
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• pp.551-557
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• 2017

Most European economies, Japan, and many governments have made it a major policy to expand the green business by disseminating heat pump technology, which has a large $CO_2$ reduction effect. The heat pump of all heat sources has been recognized as renewable energy and the policy to encourage has been implemented. In the recently revised Renewable Energy Law, the hydrothermal source (surface sea water) heat pump was newly included in renewable energy. In addition, the scope of application of heat pumps has expanded in the mandatory installation of renewable energy for new buildings, remodeling buildings, and reconstructed buildings based on this law. However application to heat pumps using all natural energy as heat source has been put off. In this revision, the ratio of renewable energy to the total energy produced by the heat pump was fixed at 73%, which depends on coefficient of performance of heat pump. The ratio of renewable energy is $1-1.8/COP_H$, and should be calculated including the coefficient of performance of the heat pump. Using a high efficiency heat pump or a high-temperature heat source increases the coefficient of performance and also reduces $CO_2$ emissions. It is necessary to expand the application of heat pumps as renewable energy equipment and to improve the correct calculation of renewable energy production.

• 한국염색가공학회지
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• 제19권2호
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• pp.14-23
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• 2007

This research article explores the use of phthalocyanine reactive dye on nylon substrate. The effect of factors such as pH, temperature, liquor ratio and alkali addition on level of dye exhaustion, fixation and total fixation efficiency. Low pH, high temperature and low liquor ratio were found to be suitable conditions for maximum % exhaustion values. The effect of sulphatoethylsulphone(SES) and vinylsulphone(VS) form of the dyes on level of dye fixation was also discussed. The optimized exhaustion (%E), fixation(%F) and total fixation efficiency were determined. Modification of the dyeing process with alkali addition displayed that dye fixation(%) increased by alkali addition. Vinylsulphone(VS) moiety of the dye was found to be superior to. maximum fixation (%F). Appropriate predictable empirical models, relatively a new approach in dyeing processes, were developed incorporating interactions effects of temperature, pH and liquor ratio for predicting % exhaustion, fixation and total fixation efficiency. The significance of the mathematical model developed was ascertained using microsoft excel regression(solver) analysis module. High correlation coefficient was obtained (R2=0.9895 for % exhaustion, R2=0.9932 for fixation, R2=0.9965 for total fixation efficiency) for the model which shows prominent prediction capacity of the model for my conditions. The predictable polynomial equations developed from tile experimental results were thoroughly analyzed by ANOVA (Analysis of Variance) statistical concepts.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.703-706
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• 1998

This paper presents an efficient substrate-bias generator(SBG)for low-power, high-density DRAM's The proposed SBG can supply stable voltage with switching the supply voltage of driving circuit, and it can substitude the small capacitance for the large capacitance. The charge pumping circuit of the SBG suffere no VT loss and is to be applicable to low-voltage DRAM's. Also it can reduce the power consumption to make VBB because of it's high pumping efficiency. Using biasing voltage with positive temperature coefficient, VBB level detecting circuit can detect constant value of VBB against temperature variation. VBB level during VBB maintaining period varies 0.19% and the power dissipation during this period is 0.16mw. Charge pumping circuit can make VBB level up to -1.47V using VCC-1.5V, and do charge pumping operation one and half faster than the conventional ones. The temperature dependency of the VBB level detecting circuit is 0.34%. Therefore the proposed SBG is expected to supply a stable VBB with less power consumption when it is used in low power DRAM's.

• 한국염색가공학회지
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• 제9권3호
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• pp.10-17
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• 1997

The study was performed to obtain the optimum extraction conditions for crocin from gardenia fructus. Generally crocin is unstable on heat, light, acid and base solution. The extraction efficiency of crocin from gardenia depended upon the extraction time, extraction temperature, pH in the extraction bath and the optimum conditions of crocin extraction were determined as 60 minutes of extraction time, 4$0^{\circ}C$ of extraction temperature, pH 7 of extraction bath. The molar extinction coefficient of crocin was 12,515 and the color yield of purified crocin was about six times higher than that of non-purified crocin. The heat-stability at extraction temperature and lightstability in irradiation with xenon lamp for one hour of the purified crocin were higher than those of non-purified crocin. Intensity of &{\lambda}_{max}&of crocin was decreased by irradiation for one hour but UV-Vis. spectra of crocin was not changed. The colors of purified and non-purified crocin dissolved wit methanol was evaluated by means of CIE L* a* b* system.

• 태양에너지
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• 제2권1호
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• pp.17-23
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• 1982

This paper presents the performance of a Flat-Plate Solar Collector in case of taking into account of the thermal capacitance. The relationships among energy absorption, overall heat loss coefficient and temperature distribution are studied theoretically. And the thermal capacitance of the collector is considered. Also, the results obtained are compared with those of model in which the thermal capacitance is neglected. As the results of this study, the efficiency of the collector having double glazing is higher than the other cases. It is shown that the fluid temperature in the tubes are rising close to linearly. The variations of the outlet temperature of tubes in the model neglecting the effect of thermal capacitance are tend to represent lower slope than that of considering the effect of thermal capacitance.

• 수산해양교육연구
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• 제26권6호
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• pp.1352-1357
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• 2014

In the present study, the heat transfer performance on the heat recovery ventilator with rotary disk were experimentally investigated. The temperature of entrance and exit of the heat recovery ventilator, air flow distribution of high temperature air and low temperature air, heat flux and the overall heat transfer coefficients are estimated from the experimental results. As the number of revolution of rotary disk, the air flow distribution increase, heat flux and overall heat transfer coefficients increase.

• 대한설비공학회지:설비저널
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• 제14권1호
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• pp.1-11
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• 1985

Solar/absorption cooling system was analyzed and its operating condition was examined. For the system, the optimum size of absorption refrigerator and collector area should be determined. As the temperature of water supplied to the generator increases, the collector efficiency decreases whereas the coefficient of performance of absorption refrigerator increases up to a certain point, and vice versa for decreasing of the temperature of water supplied to the generator . Thus if the reeling load is given, the appropriate operating condition can be determined between the two opposing trends by simulation program. As an example of the simulation, the case of Jejudo province was studied. Under the conditions (such as weather data and prices of components, etc.) given en the sample calculation, the result shows that the optimum temperature of water supplied to the generator turned out to be $80.3^{\circ}C$, and still shows a large economical disadvantage in present stage compared to the case of conventional vapor compression cooling/heating combined heat pump system.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.61.1-61.1
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• 2010

$CuIn_{1-x}-GaxSe_2$ based materials with direct bandgap and high absorption coefficient are promising materials for high efficiency hetero-junction solar cells. CIGS champion cell efficiency(19.9%, AM1.5G) is very close to polycrystalline silicon(20.3%, AM1.5G). A reduction in the price of CIGS module is required for competing with well matured silicon technology. Price reduction can be achieved by decreasing the manufacturing cost and by increasing module efficiency. Manufacturing cost is mostly dominated by capital cost. Device properties of CIGS are strongly dependent on doping, defect chemistry and structure which in turn are dependent on growth conditions. The complex chemistry of CIGS is not fully understood to optimize and scale processes. Control of the absorber grain size, structural quality, texture, composition profile in the growth direction is important to achieving reliable device performance. In the present work, CIS nanoparticles were prepared by a simple wet chemical synthesis method and their structural and optical properties were investigated. XRD patterns of as-grown nanopowders indicate CIS(Cubic), $CuSe_2$(orthorhombic) and excess selenium. Further, as-grown and annealed nanopowders were characterized by HRTEM and ICP-OES. Grain growth of the nanopowders was followed as a function of temperature using HT-XRD with overpressure of selenium. It was found that significant grain growth occurred between $300-400^{\circ}C$ accompanied by formation of ${\beta}-Cu_{2-x}Se$ at high temperature($500^{\circ}C$) consistent with Cu-Se phase diagram. The result suggests that grain growth follows VLS mechanism which would be very useful for low temperature, high quality and economic processing of CIGS based solar cells.