• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.717-729
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• 2005

Peak cooling load of large buildings is generally greater than their peak heating load. Internal and solar heat gains are used fur selection of adquate equipment in large building in cold winter climate like Canada and even Korea. The cost of geothermal heat exchanger to meet the cooling loads can increase the initial cost of ground source heat pump system to the extend less costly conventional system often chosen. Thermal ice storage system has been used for many years in Korea to reduce chiller capacity and shift Peak electrical time and demand. A distribution system designed to take advantage of heat extracted from the ice, and use of geothermal loop (geothermal heat exchanger) to heat as an alternate heat source and sink is well known to provide many benifits. The use of thermal energy storage (TES) reduces the heat pump capacity and peak cooling load needed in large building by as much as 40 to $60\%$ with less mechanical equipment and less space for mechanical room. Additionally TES can reduce the size and cost of the geothermal loop by 1/3 to 1/4 compared to ground coupled heat pump system that is designed to meet the peak heating and cooling load and also can eliminate difficuties of geothermal loop installation such as space requirements and thermal conditions of soil and rock at the urban area.

• Journal of the Korean Institute of Gas
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• v.12 no.1
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• pp.48-53
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• 2008

The condensation heat transfer coefficients of R-22 and R-410A in a small diameter tube were investigated. The main components of the refrigerant loop consist of a receiver, a variable-speed pump, a mass flowmeter, an evaporator (preheater), and a condenser (test section). The test section consists of smooth, horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The refrigerant mass fluxes varied from 450 to $1050\;kg/(m^2s)$ and the average inlet and outlet qualities were 0.05 and 0.95. The main results were summarized as follows : the condensation heat transfer coefficient also increases with increasing mass flux and quality. The condensation heat transfer coefficient of R-410A was slightly higher than that of R-22. Most of correlations proposed in the large diameter tube showed significant deviations with experimental data except for the ranges of low quality and low mass flux.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1189-1194
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• 2013

The Intermediate Heat Exchanger (IHX) of a Very High Temperature Reactor (VHTR) is a core component that transfers the high heat of $950^{\circ}C$ generated in the VHTR to a hydrogen production plant. The Korea Atomic Energy Research Institute manufactured a lab-scale prototype of a Printed Circuit Heat Exchanger (PCHE) as a candidate for an IHX. In this study, as a part of a high-temperature structural integrity evaluation of the lab-scale PCHE prototype made of SUS316L, we carried out high temperature structural analysis modeling and macroscopic thermal and elastic structural analysis for the lab-scale PCHE prototype under helium experimental loop (HELP) test conditions as a precedent study prior to the performance test in HELP.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1289-1295
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• 2012

A process heat exchanger (PHE) in a nuclear hydrogen system is a key component for transferring the considerable heat generated in a very high temperature reactor (VHTR) to a chemical reaction that yields a large quantity of hydrogen. A performance test on a small-scale PHE prototype made of Hastelloy-X is underway in a small-scale gas loop at the Korea Atomic Energy Research Institute. Previous research on the high-temperature structural analysis of the small-scale PHE prototype had been performed using base material properties. In this study, a high-temperature structural analysis considering the mechanical properties in the weld zone was performed, and the obtained results were compared with those of the previous research.

• Journal of the Korean Institute of Gas
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• v.12 no.3
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• pp.43-49
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• 2008

The evaporation heat transfer coefficient and pressure drop of R-22 and R-407C in horizontal copper tubes were investigated experimentally. The main components of therefrigerant loop are a receiver, a compressor, a mass flow meter, a condenser and a double pipe type evaporator (test section). The test section consists of a smooth copper tube of 4.3 mm and 6.4 mm inner diameter. The refrigerant mass fluxes were varied from 100 to $300[kg/m^2s]$ and the saturation temperature of evaporator were 5 [$^{\circ}C$]. The evaporation heat transfer coefficients of R-22 and R-407C rise with the increase in mass flux and vapor quality. The evaporation heat transfer coefficient of R-22 for inner diameter tube of 4.3 mm and 6.4 mm is about $7.3{\sim}47.1%$ and $5.68{\sim}46.6%$ higher than that of R-407C, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1095-1101
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• 2012

A process heat exchanger (PHE) in a nuclear hydrogen system is a key component that transfers the large amount of heat generated in a very high temperature reactor (VHTR) to a chemical reaction that yields a large quantity of hydrogen. A performance test on a small-scale and a medium-scale PHE prototype made of Hastelloy$^{(R)}$-X is being conducted on in a small-scale nitrogen gas loop at the Korea Atomic Energy Research Institute. Previous research on the macroscopic high-temperature structural analysis of PHE prototypes had been performed using base material properties owing to a lack of weld material properties. In this study, macroscopic high-temperature structural analyses considering the weld material properties were performed and the results were compared with those of a previous study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.525-531
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• 2011

Exhaust gas recirculation (EGR) is more effective than selective catalytic reduction (SCR) or lean $NO_x$ trap (LNT) for the reduction of $NO_x$ emissions in diesel engines. A large amount of EGR gas is necessary to satisfy the stringent regulations on $NO_x$ emissions. Low pressure loop (LPL) EGR is almost independent of the variable geometry turbocharger (VGT) at a specific boost pressure, so LPL EGR is better than conventional high pressure loop (HPL) EGR in terms of EGR supply. We compare the influence of HPL EGR and LPL EGR on the combustion characteristics at a constant boost pressure in a diesel engine. The dilution ratio was employed as an independent parameter to analyze the effect of the dilution of the intake charge for each EGR loop. At the same level of $NO_x$ emissions, the fuel consumption and smoke opacity were slightly lower for LPL EGR than for HPL EGR.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.189-190
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• 2008

원자력발전소의 탈기기 계통(Gas Stripper System)은 약 $25^{\circ}C$의 순수를 1.2기압, $105^{\circ}C$ 상태를 거쳐서 가스가 없는 상태(탈기)로 만들어 주는 계통이다. 탈기 상태를 유지하면서 지속적으로 순수를 만들기 위해서 본 계통에는 수위와 압력 제어루프가 있다. 탈기 상태에서는 탈기기 탱크내의 유체 상태가 이상(Two Phase)이기 차가운 급수를 사용한 수위와 압력 제어가 어렵다. 본 논문에서는 모델 기반으로 제어 최적화를 하기 위하여 제어 구성 요소들에 대한 제어 모델링 및 검증 과정을 기술한다. 제어모델링은 일반적으로 Parameter Identification 기법을 적용하지만, 유체역학 수식 모델, 운전 데이터, 탱크와 배관의 설계 자료 등을 이용한 경험적 방법을 적용하였으며 운전 데이터를 사용하여 검증하였다.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.4
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• pp.337-343
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• 2009

Purpose: ((R)-1-(2-chlorophenyl)-N-1-[$^{11}$C]methyl-N(1-propyl)-3-isoquinoline carboxamide ((R)-PK11195) is a specific ligand for the peripheral type benzodiazepine receptor and a marker of activated microglia, used to measure inflammation in neurologic disorders. We report here that a direct and simple radiosynthesis of [$^{11}$C](R)-PK11195 in mild condition using NaH suspension in DMF and one-step loop method. Materials and Methods: (R)-N-Desmethyl-PK11195 (1 mg) in DMSO (0.1 mL) and NaH suspension in DMF (0.1 mL) were injected into a semi-prep HPLC loop. [$^{11}$C]methyl iodide was passed through HPLC loop at room temperature. Purification was performed using semi-preparative HPLC. Aliquots eluted at 11.3 min were collected and analyzed by analytical HPLC and mass spectrometer. Results: The labeling efficiency of [$^{11}$C](R)-PK11195 was 71.8$\pm$8.5%. The specific activity was 11.8:$\pm$6.4 GBq/$\mu$mol and radiochemical purity was higher than 99.2%. The mass spectrum of the product eluted at 11.3 min showed m/z peaks at 353.1 (M+1), indicating the mass and structure of (R)-PK11195. Conclusion: By the one-step loop method with the [$^{11}$C]CH3l automated synthesis module, [$^{11}C$](R)-PK11195 could be easily prepared in high radiochemical yield using NaH suspension in DMF.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.6
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• pp.582-588
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• 2013

Solid Oxide Fuel Cell (SOFC) has been focused as a promising power source, which can replace a diesel engine regarding as major source of air pollution by the ship, due to high efficiency and eco-friendly. High operating temperature of SOFC is enable to secure of high efficiency, use various fuels and no need of high priced catalyst, but it may damage to components of SOFC. Therefore temperature control system has to be designed and validated before employing the fuel cell system for securing high efficiency and reliability. In this paper, instead of using typical method to validate performance of the controller, which consumes high cost and time, performance validation system using Hardware-in-the-loop simulation was developed and validated performence of the designed temperature controller for SOFC system.