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김동락(D.L. Kim),양형석(H.S. Yang),이병섭(B.S. Lee),최연석(Y.S. Choi) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
We presented the thermal design results of a protomodel of space infrared cryogenic system (PSICS) at 2005 KSME spring conference. From the design results, we knew that the radiation heat load accounts for major part of the heat loads. In order to verify the design results, we measured the radiation heat load by using boil-off calorimetry method with liquid nitrogen. The experimental result is in good agreement with the calculation one. The experimental set-up and radiation heat load measurement result of PSICS will be presented.
최연석,김동락,이병섭,양형석,정원묵,Choi, Y.S.,Kim, D.L.,Lee, B.S.,Yang, H.S.,Jung, W.M. 한국초전도학회 2008 Progress in superconductivity Vol.10 No.1
A conduction-cooled superconducting magnet system is developed for material separation. The superconducting magnet for material separation has to be designed to have a strong magnetic field in a control volume. Since the magnetic field gradient is larger at the end rather than at the center of the magnet, we developed a design method to optimize the superconducting magnet for material separation. The safety of the superconducting magnet is evaluated, taking into account the electro-magnetic field, heat and structure. The superconducting coil is successfully wound by the wet-winding method. The superconducting coil is installed in a cryostat maintaining high vacuum, and cooled down to approximately 4 K by a two-stage GM cryocooler. The performance of the conduction-cooled superconducting magnet system is discussed with respect to the supplied current, cooling medium and cooling power of a cryocooler.
초전도자석 시스템 응용을 위한 멀티-컨텍 커넥터의 열 발생 특성 평가
김명수,최연석,김동락,이윤아,Kim, M.S.,Choi, Y.S.,Kim, D.L.,Lee, Y.A. 한국초전도학회 2012 Progress in superconductivity Vol.14 No.2
Current leads are one of the important components for carrying the current to the coil in the superconducting magnet system. Heat leakage through the current lead is the major factor of entire heat load in the cryogenic system because current leads carry the current from room temperature to near 4 K, connecting thermally each other. Therefore, minimization heat load through current lead can reduce the operating temperature of superconducting magnet. The semi-retractable current lead, composed of multi-contact connector and HTS element, is one of good options. Comprehension of Multi-contact connector's structure, contact resistance and heat generation is essential for estimating heat generation in current leads. Multi-contact connector has several louvers inside of socket and the shape, number, size of louvers are different with the size of connector. Therefore contact area, current path and contact resistance are also different. In this study, the contact resistance in multi-contact connector is measured using the electrical power as a function of connector's size and temperature. Also, the unique correlation of electrical contact resistance is derived and heat generation is estimated for superconducting magnet application.
양형석(H.S. Yang),김동락(D.L. Kim),손송호(S.H. Sohn),임지현(J.H. Lim),최하옥(H.O. Choi),최연석(Y.S. Choi),이병섭(B.S. Lee),정원묵(W.M. Jung),류희석(H.S. Ryoo),황시돌(S.D. Hwang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
A system for the 3-phase 100-m HTS power cable with 22.9㎸/1.25㎄ has been tested at the KEPCO뭩 Gochang power testing center since 2006. The cooling system consists of a liquid nitrogen decompression cooing system with a cooling capacity of 3㎾ at 66K and a closed circulation system of subcooled liquid nitrogen. Heat loads of the KEPCO HTS power cable system for several electrical loads were measured for investigating long-term operating performance such as cooling capacity, heat load, AC loss, temperature stability of the system.
Thermal Characteristic of Natural Circulation Loop for Cryogenic Cooling Application
최연석(Y.S. Choi),김동락(D.L. Kim),양형석(H.S. Yang),문성주(S.J. Moon),김재휘(J.W. Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The natural circulation loop by a cryocooler for cryogenic cooling application is designed, fabricated and tested. In the natural circulation loop system, a cooling channel is attached on the outer surface of the aluminum block and the cryogenic liquid passes through inside of the channel in order to cool the block indirectly. A cryocooler as a heat sink is located at the top to recondense cryogenic liquid coming from the aluminum block in which electrical heater as a heat source is installed. The main dimensions are determined using the existing empirical correlation and the natural circulation loop is successfully fabricated. The initial cooling using liquid nitrogen and temperature distribution of an aluminum block is discussed.
양형석(H.S. Yang),김동락(D.L. Kim),손송호(S.H. Sohn),임지현(J.H. Lim),최연석(Y.S. Choi),황시돌(S.D. Hwang) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The KEPCO HTS power cable system of 100 m, 22.9 ㎸, 1.25 ㎄ has been installed and tested at the KEPCO's Gochang power testing center in Korea since 2006. A liquid nitrogen decompression cooling system with a cooling capacity of 3 ㎾ at 66 K and a closed-circulation system of subcooled liquid nitrogen were employed for this purpose. Several cooling characteristic tests for the system, such as cooling capacity, electrical loading, heat load, ac loss and temperature stability, were performed under several different operation conditions. In this paper, we discuss about cooling characteristics of the system.
최연석(Y.S. Choi),김동락(D.L. Kim),문성주(S.J. Moon),양형석(H.S. Yang),김재휘(J.W. Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The natural circulation loop by a cryocooler is designed and fabricated. This study is motivated mainly by our recent development of cryogenic cooling system for superconducting cyclotron K120 magnets without any replenishment of the cryogen. In the natural circulation system, a cooling channel is attached on the outer surface of the aluminum block and the cryogenic liquid passes through inside. of the channel in order to cool the block indirectly. A cryocooler is located at the top to recondense cryogenic liquid coming from the aluminum block. The experimental apparatus has a similar configuration to the recently designed superconducting magnet system for cyclotron K120, except that the electrical heater is used to simulate the heat generation in the superconducting windings. The heat transfer in the natural circulation loop is discussed and the detail of design as well as fabrication is also described.
양형석(H.S. Yang),김동락(D.L. Kim),손송호(S.H. Sohn),임지현(J.H. Lim),최하옥(H.O. Choi),이병섭(B.S. Lee),최연석(Y.S. Choi),류희석(H.S. Ryoo),황시돌(S.D. Hwang) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
As a power transmission line supplying power to a densely populated city, the high temperature superconducting (HTS) cable is expected to one of the most effective cables with a compact size because of its high current density. The verification of HTS power cable system have been progressed by KEPRI. A cooling system for a 3-phase 100m HTS power cable with 22.9㎸/1.25㎄ was installed and tested at KEPCO’s Gochang power testing center in Korea. The system consists of a liquid nitrogen decompression cooling system with a cooling capacity of 3㎾ and a closed circulation system of subcooled liquid nitrogen. Several performance tests of the cable system with respect to the cooling such as cooling capacity, heat load and temperature stability, were performed at several temperatures. Thermal cycle test, cool-down to liquid nitrogen temperature and warm-up to room temperature, was also performed to investigate thermal cycle influences. The outline of the installed cooling system and performance test results are presented in this paper.