• Proceedings of the KIEE Conference
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.104-106
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• 1998

For the development of the 0.7 MJ small-sized superconducting magnetic energy storage (${\mu}$SMES) device, quench currents of a kA class superconducting cable were tested for various winding tensions because a dry superconducting coil is usually quenched by an abrupt heat pulse due to strand motions. The test coil similar to parameters of the optimally designed 0.7 MJ ${\mu}$SMES except a stored energy and a size was fabricated based on the test results of the kA class superconducting cable and tested. These experimental results show that the highly prestressed test coil has an excellent DC performance in spite of a dry type coil but its quench current is much degraded even at the low field ramping rate of about 0.4 T/s.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1252-1254
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• 2005

High Tc superconducting(HTS) model coil was prepared. Current-voltage(I-V) characteristic curves of model coil, sub-coils and joints were investigated at 77K and other some temperatures. Cooling system for characteristics measurement was made by using G-M cryocooler. At 77K, quench current(Iq) of model coil was 43.9A and the lowest Iq of sub-coils was 38.8A. At 55K, sub coil SP #06 was 106A. So, 100A was chosen as the operating current at 55K with margin. Joule heat of model coil was 0.65W at 100A, operating current and 58K. Joint resistances between sub-coils were about $70n{\Omega}$ at 77K and about $30n{\Omega}$ at 55K.

• Journal of Ocean Engineering and Technology
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• 제37권5호
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• pp.215-224
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• 2023

While melting glaciers due to global warming have facilitated the development of polar routes, Arctic vessels require reliable anti-icing methods to prevent hull icing. Currently, the existing anti-icing method, i.e., the heating coil method, has disadvantages, such as disconnection and power inefficiency. Therefore, a carbon nanotube-based surface heating element method was developed to address these limitations. In this study, the numerical analysis of the surface heating element method was performed using ANSYS. The numerical analysis included conjugate heat transfer and computational fluid dynamics to consider the conduction solids and the effects of wind speed and temperature in cold environments. The numerical analysis method of the surface heating element method was validated by comparing the experimental results of the heating coil method with the numerical analysis results (under the -30 ℃ conditions). The surface heating element method demonstrated significantly higher efficiency, ranging from 56.65-80.17%, depending on the conditions compared to the heating coil method. Moreover, even under extreme environmental conditions (-45 ℃), the surface heating element method satisfied anti-icing requirements. The surface heating element method is more efficient and economical than the heating coil method. However, proper heat flux calculation for environmental conditions is required to prevent excessive design.

• Proceedings of the KIEE Conference
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.86-88
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• 1997

The detection of the normal zones in the coil winding and the initiation of the proper dump sequence have been one of the most important areas in the superconducting magnet technology. In this paper, the process to derive optimal dump sequence has been investigated through quench simulation and analysis of magnetically coupled superconducting magnet system. The magnet terminal voltage and maximum temperature rise in the quench initiated point are calculated with respect to various input variables such as operation current, dump resistance, etc. The experimental system is comprised of sc solenoidal coil, data aquisition device, external circuit breakers and dump resistor. The quench behavior of the magnet(e.g., temperature profile and the voltage signal) was measured. From this results, theoretical predictions were found to coincide with the experimental observations.

• Proceedings of the Korean Society of Veterinary Service Conference
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• 한국가축위생학회 1995년도 제18차 학술대회 및 정기총회
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• pp.82.2-83
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• 1995

• The Korean Journal of Zoology
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• 제38권4호
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• pp.565-569
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• 1995

We have previoosly demonstrated that the RecA-like protein of Schizosaccharomyces pombe (S. pombe) is immunologically related to Escherichia coil (E. coil) RecA protein and that the cellular level of the protein is significantly increased by inhibitors of nucleotide pool-forming enzymes such as hydroxyurea (HU) and methotrexate (MTX) (lee and Park, 1994; lee et al., 1994). In this study, we report that the ribonudeotide redudase activity of S. pombe is inhibited by E. coil RecA antibody, as determined by thin layer chromatography using [5-$^3$H]CDP as a substrate. The relative activity of ribonucleotide reductase was dramatically inhibited by 100 mM of flu (26.4% reduction) in in vitro assay, compared to that of non-treated control. The ribonucleotide reductase activity was also inhibited by immunoprecipitation with E. coil RecA antibody (43.3% reduction). These results indicate that the strudure of S. pombe ribonucleotide reductase is in part similar to that of E. coil RecA protein.

• Proceedings of the KIPE Conference
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.625-626
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• 2012

A coupled magnetic resonance system (CMRS) using compact coil sets with core driven by a class-E inverter was proposed. The source and load coils of conventional CMRS were replaced with two coils containing core so that the system can be quite compact in size and easy to design due to a resonance frequency for all resonant tanks regardless of coupling factor. Experiments for 500 kHz switching frequency show 40% system efficiency.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1164-1169
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• 2008

The miniaturization of the Air Handling Unit (AHU) has become an actual need because of the restriction of the using space on the vessel. In modern AHU’s construction, in which the fan section is at the end part of the ship, it’s very difficult to select a suitable capacity of evaporators, because the fan motor emits heat. Thus, the AHU structure has been changed as the fan section has been set before the cooling coil to get temperature values similar to the designed amount. Also, the air guider is installed in order to maintain equal air distribution after it passed the fan section. So, it is possible for air to equally pass the cooling coil. It is investigated three different geometries to find the best performance. Also, It is compared with the numerical and experimental results. The study found the case 3 gives the best results. The results of this study show the possible application of the new design.

• Proceedings of the KIEE Conference
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.665-666
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• 2008

Inserted HTS (high temperature superconducting) coil is promisingly expected as a solution for achievement of higher fields such as GHz scale NMR magnet. However, HTS magnet causes persistent current decay in the persistent current mode and this decay should be compensated in order to keep stable magnetic field. As a solution for the decay in the HTS magnets, we proposed a new type superconducting power supply, i.e., linear type magnetic flux pump (LTMFP). The LTMFP mainly consists of DC bias coil, 3-phase AC coil and superconducting Nb foil. The compensating current in closed superconductive circuit can be easily controlled by the intensity of 3-phase AC current and its frequency. In this study, it has been investigated that the flux pump can effectively charge the current for various frequencies according to the different load magnets.

• Nuclear Engineering and Technology
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• 제30권4호
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• pp.377-385
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• 1998

Many nuclear power plants have experienced unscheduled shutdown due to the leakage of steam generator tubes. The leakages are normally due to the crack, possibly stress corrosion cracking (SCC) near the tube expansion at the top of tubesheet or at the tangential point of the row-1 U-bend region. The conventional eddy current technique, which makes use of a differential bobbin coil, has been found to be inadequate for the early detection of SCC. During the in-service inspection, therefore, it is a general practice that the rotating pancake coil (RPC) is used for detecting the cracks. Even in using RPC, however, it is difficult to determine the depth of the cracks quantitatively. This paper attempts to determine the detectability and sizing ability of RPC technique for axial or circumferential cracks at the tube expansion region. The simulated cracks with various dimensions were fabricated by electro-discharge machining (EDM) method. Experimental results are discussed with theoretical calculations.