• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.415-417
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• 2005

In order to retrieve the latent and sensible heat fluxes, high-resolution airborne imageries with visible, near infrared, and thermal infrared bands and ground-base meteorology measurements are utilized in this paper. The retrieval scheme is based on the balance of surface energy budget and momentum equations. There are three basic surface parameters including surface albedo $(\alpha)$, normalized difference vegetation index (NOVI) and surface kinetic temperature (TO). Lowtran 7 code is used to correct the atmosphere effect. The imageries were taken on 28 April and 5 May 2003. From the scattering plot of data set, we observed the extreme dry and wet pixels to derive the fitting of dry and wet controlled lines, respectively. Then the sensible heat and latent heat fluxes are derived from through a partitioning factor A. The retrieved latent and sensible heat fluxes are compared with in situ measurements, including eddy correlation and porometer measurements. It is shown that the retrieved fluxes from our scheme match with the measurements better than those derived from the S-SEBI model.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.6
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• pp.434-440
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• 2007

One of the cold start problems of a FCV is the freezing of the water in the water tank when a FCV is not in operation and the surrounding temperature drops below $0^{\circ}C$. The ice in the tank should be melted as quickly as possible for a satisfactory operation of fuel cell vehicles. In this study, the melting process for the constant heat fluxes of the plate heaters was numerically calculated in the 2-D model of the tank and plate heaters. The enthalpy method and FVM code was used for this analysis. The changes of the temperature with heat fluxes and the heat transfer area could be investigated. The energy balance error was found to increase with the heat flux. From this numerical analysis, the proper heat flux value and some important design factors relating local overheating and pressurization of the water tank could be examined.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.161.2-161.2
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• 2010

페로니켈 제조 공정에 있어서 석탄의 비중은 총 에너지원 중 70%에 상당하며, 온실가스 배출 또한 65%에 달한다. 이에 석탄을 대체할 물질로서 RPF, RDF, Biomass, TDF 등을 고려하였으며, 자체 개발한 열정산 프로그램을 활용하였다. 해석결과 석탄 대체물질의 사용할 경우 페로니켈 제조공정의 에너지 비용을 상당량 저감할 수 있을 것으로 기대된다.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.63-67
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• 2021

해외 발전사업의 기술 경쟁력 우위 선점을 위해서는 발전시스템에 대한 최적설계기술 및 발전소 운영 기간 중 최소 비용으로 높은 신뢰도의 설비 관리, 최적 성능 유지를 할 수 있는 O&M 관리 기술이 필요하다. 전력연구원은 해외발전사업 전주기 기술지원을 위한 연구개발을 수행하고 있다.

• Steel and Composite Structures
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• v.30 no.3
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• pp.281-292
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• 2019

In this paper, analysis of critical fluid velocity and heat transfer in the nanocomposite pipes conveying nanofluid is presented. The pipe is reinforced by carbon nanotubes (CNTs) and the fluid is mixed by $AL_2O_3$ nanoparticles. The material properties of the nanocomposite pipe and nanofluid are considered temperature-dependent and the structure is subjected to magnetic field. The forces of fluid viscosity and turbulent pressure are obtained using momentum equations of fluid. Based on energy balance, the convection of inner and outer fluids, conduction of pipe and heat generation are considered. For mathematical modeling of the nanocomposite pipes, the first order shear deformation theory (FSDT) and energy method are used. Utilizing the Lagrange method, the coupled pipe-nanofluid motion equations are derived. Applying a semi-analytical method, the motion equations are solved for obtaining the critical fluid velocity and critical Reynolds and Nusselt numbers. The effects of CNTs volume percent, $AL_2O_3$ nanoparticles volume percent, length to radius ratio of the pipe and shell surface roughness were shown on the critical fluid velocity, critical Reynolds and Nusselt numbers. The results are validated with other published work which shows the accuracy of obtained results of this work. Numerical results indicate that for heat generation of $Q=10MW/m^3$, adding 6% $AL_2O_3$ nanoparticles to the fluid increases 20% the critical fluid velocity and 15% the Nusselt number which can be useful for heat exchangers.

• Journal of Nutrition and Health
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• v.16 no.4
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• pp.233-242
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• 1983

This study was attempted to investigate Korean women divers' nutritional status and the effect of their putting on rubber diving suits on the energy balance. For these investigations, measurements of nutrients intake, energy intake and energy consumption during diving work were performed. This study was conducted in summer and winter of 1981. Nutrition survey was carried out by interviewing each individual and the energy consumption during diving work was calculated from the extra oxygen consumption over the resting value and the change in mean body temperature in sea water. The results obtained were summarized as follows : 1) In summer, the divers' dietary intake were 2,454 Kcal for energy, 69g of protein, 16g of fat 578mg of calcium, 11mg of iron, 526 Retinol Equivalent of vitamin A, 1.1mg of thiamin, 1.3mg of riboflavin, 19mg of niacin and 50mg of ascorbic acid. These results showed that the intakes of energy, thiamin, riboflavin, niacin and ascorbic acid were higher than the Korean Recommended Dietary Allowances (RDA). Whereas in winter, the nutrients intake except iron, riboflavin, and vitamin A were higher than the RDA. 2) The energy consumption, measured by oxygen consumption and changes in body heat content, used in diving work were 260 Kcal per day in summer and 370 Kcal per day in winter. These values were about 600-700 Kcal per day lower than 1960s' 1,000 Kcal per day. The divers' energy intake were 2,454 Kcal per day in summer and 2,487 Kcal per day in winter. These data were about 550 Kcal per day lower than 1960s' intake. Since divers have worn the rubber diving suits, the energy consumption decreased as compared with the energy consumed while wearing cotton suits. And this seemed to be resulted in decreasing the energy intake. This result also showed that the balance between energy expenditure and energy intake were kept. 3) The mean subcutaneous fat thickness of divers and nondivers were 8.85 and 9.03 mm respectively. These values were as high as four times as those of 1960s'. The total body fat contents wers 25.8 percent in both diver and nondiver groups and showed an increase as high as twice as compared with 1960s' values.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.6
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• pp.796-803
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• 2003

The discrete ordinates interpolation method (DOIM) has shown good accuracy and versatile applicability for the radiation $problems^{(1,2)}$. The DOIM is a nonconservative method in that the intensity and temperature are computed only at grid points without considering control volumes. However, when the DOIM is used together with a finite volume algorithm such as $SIMPLER^{(3)}$, intensities at the control surfaces need to be calculated. For this reason, a 'quadratic' and a 'decoration' schemes are proposed and examined. They are applied to two kinds of radiation problem in one-dimensional geometries. In one problem, the intensity and temperature are calculated while the radiative heat source is given, and in the other, the intensity and the radiative heat source are computed with a given temperature field. The quadratic and the decoration schemes show very successful results. The quadratic scheme gives especially accurate results so that further decoration may not be needed. It is recommended that the quadratic and the decoration schemes may be used together, or, one of them may be applied for control volume radiative energy balance.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.4
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• pp.555-560
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• 2008

The effects of utilizing evaporative cooling system equipped with tunnel ventilation on postpartum ovarian activities, energy balance and milk production of early lactating dairy cows under hot and humid climates were studied from parturition to 22 wk postpartum. Thirty-four crossbred Holstein-Friesian (93.75% HF$\times$.25% Bos indicus) primiparous cows were randomly assigned to one of two groups. Cooled cows (n = 17; treatment) were housed in the tunnel ventilated barn equipped with evaporative cooling system and uncooled (n = 17; control) were housed in the naturally ventilated barn without supplemental cooling system. Cooled cows had greater (p<0.05) dry matter intake and milk production than uncooled cows. Days to the energy balance (EB) nadir did not differ between groups. However, days to equilibrium EB for uncooled cows was longer (p<0.05) than for cooled cows. There was no significant difference in postpartum anovular condition between cooled and uncooled cows. The interval from parturition to first postpartum ovulation did not differ between groups ($31.4{\pm}4.3$ and $26.1{\pm}3.6$ day, respectively). These results suggest that the evaporative cooling and tunnel ventilation has the potential to decrease the severity of heat stress and improve both milk production and metabolic efficiency during early lactation without affecting reproductive function in dairy cows under hot and humid climates.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.676-679
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• 2007

This paper describes an experiment facility to measure the circulation characteristics of a water/steam receiver at various heat fluxes. The natural circulation type receiver was considered in this study. The experiment facility was designed to satisfy circulation balance with an appropriate scale down. As a result, riser tube inner diameter was 7.4 mm and water circulation was 0.319 kg/s. Downcomer tube inner diameter by circulation balance was 9.52 mm and the quality was from 0 to 0.23.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.7
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• pp.1001-1012
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• 1998

This paper reports the analysis of dynamic characteristics of air-cooled condenser. At first, there is an assumption that the superheated vapor flows into the condenser inlet. And in order to consider the effect of pressure change in the dynamic characteristics of the condenser the combined system of condenser and compressor was used. By using the equation of energy balance and the equation of mass balance, the basic equation for describing the dynamic characteristics of condenser can be derived. The transfer function for describing dynamic response of the condenser to flow rate change outlet can be obtained from using linearizations and Laplace transformations of the equation. From this transfer function, analytical investigation which affects the frequency responses of condenser has been made. Through this study, it became possible that the information about the dynamic characteristics of air-cooled condenser is offered. While the average heat transfer coefficient of the refrigerant side necessary for the theoretical calculation of the dynamic characteristics is given by calculation method for the tube length and pressure drop of air-cooled condenser.