KSTAR 전류인입선 및 헬륨냉매 제어시스템 제작 및 설치

송낙형,우인식,이영주,곽상우,방은남,이근수,김정수,장용복,박현택,홍재식,박영민,김양수,최창호,Song, N.H.,Woo, I.S.,Lee, Y.J.,Kwag, S.W.,Bang, E.N.,Lee, K.S.,Kim, J.S.,Jang, Y.B.,Park, H.T.,Hong, J.S.,Park, Y.M.,Kim, Y.S.,Choi, C.H. 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.5

KSTAR (Korea Superconducting Tokamak Advanced Research) 전류인입선(CL; Current Lead)은 4.5 K의 저온에서 운전되는 초전도 버스라인과 300 K의 실온에서 운전되는 MPS (Magnet Power Supply)를 전기적으로 연결하는 장치이다. 초기 플라즈마 발생시험을 위하여 TF (Toroidal Field) 및 PF (Poloidal Field) 리드박스에 전류인입선이 설치된다. TF 자석용 CL은 17.5 kA급 4 개의 CL에 최대 35 kA의 DC 전류가 인가되며, PF 자석용은 13 kA급 14 개의 CL에 350초간 $20\;{\sim}\;26\;kA$의 펄스 전류가 인가된다. 각각의 전류인입선은 TF 및 PF 자석에 전류를 인가하기 위한 버스라인이 연결되어 있으며, 전류인입선을 통해 초전도 버스라인으로 전달되는 전도열 및 전류인가시 발생되는 주울(Joule) 열을 차단하기 위한 헬륨냉매 제어시스템이 KSTAR 주장치와는 별도로 설치되어 있다. 리드박스 내 외부의 배관 및 제어시스템 설치완료 후 고진공 배기, 헬륨 누설검사, 전류인입선 유량 검사 및 액체질소 냉각시험을 실시하여 장치의 성능검증을 완료하였다. KSTAR (Korea Superconducting Tokamak Advanced Research) current lead system (CLS) has a role to interconnect magnet power supply (MPS) in room temperature (300 K) and superconducting (SC) bus-line, electrically. For the first plasma experiments, it should be assembled 4 current leads (CL) on toroidal field (TF) current lead box (CLB) and 14 leads on poloidal field (PF) CLB. Two current leads, with the design currents 17.5 kA, and SC bus-lines are connected in parallel to supply 35 kA DC currents on TF magnet. Whereas, it could supply $20\;{\sim}\;26\;kA$ to each pairs of PF magnets during more than 350 s. At the cold terminals of the leads, there are joined SC bus-lines and it was constructed helium coolant control system, aside from main tokamak system, to protect heat flux through current leads and enhanced Joule heat due to supplied currents. Throughout the establishment processes, it was tested the high vacuum pumping, helium leak of the helium lines and hardwares mounted between the helium lines, flow controls for CL, and liquid nitrogen cool-down of possible parts (current leads, CL helium lines, and thermal shield helium lines for CLB), for the accomplishment of the required performances.

Design and CFD analysis of hypervapotron-typed ion dump for KSTAR NBI-2 system

Kim, K.M.,Chang, Y.B.,Kim, H.T.,Kwon, S.,Song, N.H.,Lee, K.S.,Park, H.T.,Kim, J.S.,Lim, D.S.,Kwag, S.W.,Im, K.,Hong, S.H.,Kim, Y.S. Elsevier 2018 Fusion engineering and design Vol.136 No.2

<P><B>Abstract</B></P> <P>The NBI-2 system for the KSTAR has been designed to provide plasma heating and current for maximum 300 s which has the capability of 6 MW of deuterium neutral beam power. The NBI-2 system is under construction on site to be operated for the beam injection into the KSTAR plasma from the 2018 KSTAR campaign. The ion dump modules consist of the full, half, and third energy components is positioned on one side of the bending magnet. The ion dump of KSTAR NBI-2 system is designed with a hypervapotron-typed channel to withstand a heat flux of about 6.7 MW/m<SUP>2</SUP> that was calculated by the beam transfer code simulation. The water flow rate supplied to each hypervapotron channel of the ion dump is about 1.9 kg/s at inlet. The inner size of the hypervapotron channel is modified to reduce a pressure drop and a liquid velocity difference in the channel.</P> <P>The CFD analysis using Ansys CFX is performed to verify its availability in the high heat flux condition. There is no problem to use the ion dump of the KSTAR NBI-2 system because the maximum temperature of the ion dump body made of CuCrZr is about 428.4 °C which is below allowable temperature of 500 °C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This manuscript presents the design of the ion dump for the KSTAR NBI-2 system and the results of the CFD analysis using Ansys CFX. </LI> <LI> The ion dump of the KSTAR NBI-2 has been designed to use a hypervapotron-typed channel to withstand the maximum heat flux of about 6.7 MW/m<SUP>2</SUP>. </LI> <LI> The surface temperature on the single phase flow condition analysis is lower than one on the sub-cooled boiling condition analysis. </LI> <LI> The ion dump of the KSTAR NBI-2 is expected to operate below the allowable temperature because the maximum temperature of the ion dump is about 428.4 °C. </LI> </UL> </P>

Construction and Commissioning of the KSTAR Helium Distribution System

Lee, Y.J.,Park, Y.M.,Kim, Y.S.,Jang, H.S.,Kwag, S.W.,Chang, Y.B.,Park, H.T.,Woo, I.S.,Song, N.H.,Bang, E.N.,Ha, T.H.,Baek, S.,Kim, M.K.,Kim, W.C.,Oh, Y.K.,Bak, J.S. IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3

<P>The KSTAR components requiring cryogenic helium coolant for superconducting magnet operations are connected to the helium refrigeration system (HRS) through the helium distribution system (HDS), the final helium distribution station. Twenty eight cryogenic valves including 4 quench protecting valves, many sensors such as temperature sensors, pressure transmitters, and flowmeters are mounted on the system. The HDS has to control the 4.5 K supercritical helium (600 g/s) for 30 superconducting coils and their superconducting bus-lines, 55 K helium (270 g/s) pressurized to 18 bars for the thermal shields and the gravity supports, and a maximum 17.5 g/s of liquid helium for 18 current leads, provided from the HRS which has a 4.5 K equivalent cooling power of 9 kW. The helium distribution system consists of a helium distribution box (DB), 5 helium transfer lines, a PLC based helium control system (HCS), etc. The helium control system is connected to the KSTAR supervisory control & interlock system. The detailed status regarding the construction, commissioning during first cool-down, and the instrumentation & control (I&C) system are included in this paper.</P>

돈분이용 퇴비화과정에서의 공기공급량별 퇴비화 특성변화에 관한 연구

곽정훈,김재환,정광화,조승희,안희권,최동윤,정만순,이상철,강희설,라창식,Kwag, J.H.,Kim, J.H.,Jeong, K.H.,Cho, S.H.,Ahn, H.K.,Choi, D.Y.,Jeong, M.S.,Lee, S.C.,Kang, H.S.,Ra, C.S. 한국축산환경학회 2011 축산시설환경학회지 Vol.17 No.2

스크레퍼 이용 수거된 돈분을 호기성 조건으로 퇴비화 하는 과정에서 공기공급량을 50, 100, 150, 200$\ell/m^3$/min.으로 각각 다르게 하여 퇴비화 하는데 있어서 공기공급량을 다르게 하여 퇴비화기간동안의 퇴비특성을 조사한 결과는 다음과 같다. 1. 퇴비화원료로 사용된 돈분의 수분함량은 85%였으며 수분 조절재로 사용한 톱밥의 수분함량은 35%를 혼합하여 수분 68%로 조정한 후 퇴비화 시험을 실시하였다. 2. 돈분의 호기성 퇴비화를 실시하는 과정에서 퇴비화기간동안의 발효온도를 조사한 결과 T-1 처리구에서 발효온도가 다른 처리구에 비해서 낮은 것으로 조사되었으며 이는 T-1 처리구에서는 정상적인 호기성 발효가 진행되지 않고 있음을 보여주고 있었다. 반면에 T-3 및 T-4 처리구에서는 최고온도 도달시간이 다른 처리구에 비하여 짧다는 것은 계분의 신속한 퇴비화 및 높은 수분 증발량이 조사되었다. 3. 처리구별 수분 함량 변화를 분석해 본 결과 발효 초기의 경우에 공기 공급량을 T-1 처리구에서 1주일이 경과한 후 7.6%로 가장 낮게 조사되었으며, T-2, T-3 및 T-4 처리구에서는 각각 13.2%, 16.8% 및 16.9%로 높은 수분 감소량을 보이는 것으로 조사되었으며, T-3 및 T-4 처리구와 나머지 처리구간에 통계적으로 유의적인 차이가 있는 것으로 조사되었다 (p>0.05). 4. 처리구간별 배출되는 가스성분 중에서 산소 농도를 측정한 결과 모든 처리구에서 퇴비화 3일차까지 9 ppm으로 낮은 수치로 조사되어 모든 처리구가 정상적인 호기성 퇴비화가 진행되는 것을 확인 할 수 있었다. 5. 퇴비화 시험 1주일 후의 중량 감소율은 T-1 처리구에서 7.6%로 가장 낮았으며, T-3 및 T-4구에서는 16.8% 및 16.9%로 비슷한 경향이 조사되었다. 6. 퇴비화기간의 경과에 따른 비료성분 및 유기물 량은 처리구간에 큰 차이를 보이지 않았으나, 1차 발효 후 비료성분 함량은 처리구별로는 T-4 처리구에서 질소성분이 타 처리구에 비하여 낮아진 것으로 조사되었다. 이는 퇴비화 과정에서의 수분 함량 변화에 따라 비료성분의 함량에 차이를 보이는 것으로 조사되었다. 7. 따라서 돈분을 호기성 방법으로 퇴비화 할 경우 적정 공기공급량은 퇴비더미 $1m^3$당 최소 $1m^3$당 150$\ell$/min 이상을 공급하는 것이 적당한 것으로 판단되어 졌다. This study was carried out to investigate on the composting characteristics variation accoding to air supply capacity in Pig manure. The composting of pig manure is economical and efficiently process. The fermented compost was added in pig manure mixed with sawdust was composting reators. Air supply capacity levels of fermented compost on the pig manure mixed with sawdust were regulated at 50, 100, 150 and 200$\ell/m^3$/min. respectively. The obtained results can be followed as bellow; The temperature variations of experimental composting piles during composting for the different of T-1 reach $40^{\circ}C$ in 2 days, T-2, T-3 and T-4 reach $60^{\circ}C$ in 2 days and T-3, T-4 maintained until 8 days. The decreases in water contents per each square meter for the different of T-1 (50 l/$m^3$/min), T-2(100 l/$m^3$/min), T-3(150 l/$m^3$/min) and T-4(200 l/$m^3$/min.), The decreases ratio in water contents was T-1, T-2, T-3 and T-4 were 15.4%, 28.8%, 33.4% and 35.2%. The decreases ratio in weight was T-1, T-2, T-3 and T-4 were 7.6%, 15.6%, 16.8% and 16.9% respectively. The variations of oxygen concentration from composting period in case of oxygen discharge concentration T-1, T-2, T-3 and T-4 were 9 ppm. respectively. Fertilizer components after composting were examined. Nitrogen contents of the T-1, T-2, T-3 and T-4 were 0.45%, 0.44%, 0.42% and 0.44%, and P2O5 contents were T-1, T-2, T-3 and T-4 were 0.37%, 0.41%, 0.42% and 0.44% respectively. Therefore, the compost curing air supply of air volumes at least 150$\ell$/min/min. or more to supply the aerobic composting pig manure normally are judged to be possible.

공기공급량에 따른 산란계분의 퇴비화 특성변화에 관한 연구

곽정훈,조승희,정광화,김재환,최동윤,정의수,정만순,강희설,라창식,Kwag, J.H.,Cho, S.H.,Jeong, K.H.,Kim, J.H.,Choi, D.Y.,Jeong, Y.S.,Jeong, M.S.,Kang, H.S.,Ra, C.S. 한국축산환경학회 2010 축산시설환경학회지 Vol.16 No.2

산란계분을 퇴비화 하는데 있어서 공기공급량을 다르게 하여 퇴비화기간동안의 퇴비 특성을 조사한 결과는 다음과 같다. 1. 퇴비화기간동안의 발효온도를 조사한 결과 T-1 처리구에서 발효온도가 다른처리구에 비해서 낮은 것으로 조사되었으며 이는 T-1 처리구에서는 정상적인 호기성 발효가 진행되지 않고 있음을 보여주고 있었다. 반면에 T-3 및 T-4 처리구에서는 최고온도 도달시간이 다른 처리구에 비하여 짧다는 것은 계분의 신속한 퇴비화 빛 높은 수분증발량이 조사되었다. 2. 공기공급량에 따른 퇴비화 과정에서의 처리구별 수분함량을 분석해 본 결과 발효 초기의 경우에 공기 공급량을 T-1 처리구에서 1주일이 경과한 후 8.9%로 가장 낮게 조사되었으며, T-2, T-3 및 T-4 처리구에서는 각각 15.4%, 18.0% 및 18.6%로 높은 수분감소량을 보이는 것으로 조사되어 통계적으로 유의적인 처리가 있는 것으로 조사되었다(p>0.05). 3. 계분의 퇴비화 과정에서의 공기공급량에 따른 산소소모량을 조사한 결과 T-3 및 T-4구에서 퇴비화시험 2일째 9 ppm으로 낮은 수치로 조사되었으나 T-1 및 T-2 처리구에서는 12 ppm으로 상대적으로 높은 수치로 조사되었다. 4. 처리구별 퇴비더미내의 중량변화는 시험 1주일 후의 중량감소율은 T-1 처리구에서 5.5%로 가장 낮았으며, T-3 및 T-4구에서는 12.0% 및 12.3%로 비슷한 경향을 조사되었으며 이러현 경향은 퇴비화 2주일이 경과한 후에도 같은 경향으로 조사되었다. 5 퇴비화기간의 경과에 따른 비료성분 및 유기물량은 처리구간에 큰 차이를 보이지 않았으나, 1 차 발효후 비료성분 함량은 처리구별로는 T-4 처리구에서 질소성분이 타 처리구에 비하여 낮아진 것으로 조사되었다. 이는 퇴비화 과정에서의 수분함량 변화에 따라 비료성분의 함량에 차이를 보이는 것으로 조사되었다. 6. 반면에 OM/N도 투입시 처리구간에 큰 차이를 보지지 않았으나 1차 퇴비화 후에는 42.0, T-2 44.2, T-3 47.1 및 T-4 55.8로 공기 공급량이 높아짐에 따라 OM/N의 비가 점차 높아지는 경향으로 조사되었다. 7. 따라서 산란계분의 퇴비화시 공기공급량을 최소 퇴비화물질 $1m^3$당 $150\;{\ell}/min$ 이상 공급하는 것이 계분이 정상적으로 호기성 퇴비화가 가능하다고 판단되어 진다. The composting of layer manure is economical and efficiently process. In this study, the variation of composting characteristics in layer manure was investigated according to air supply capacity. The fermented compost was added in layer manure and mixed with sawdust inside composting reactors. The level of air supply capacity was varied in the range of $50{\sim}200\;{\ell}/m^3/min$. During composting the temperature variations of composting piles was different the temperatures of composting piles for T-1 ($50\;{\ell}/m^3/min$) and T-2 ($100\;{\ell}/m^3/min$) were reached at $40^{\circ}C$ and $50^{\circ}C$ within 2 days, respectively. For T-3 ($150\;{\ell}/m^3/min$) and T-4 ($200\;{\ell}/m^3/min$), their temperatures was $60^{\circ}C$ within same days and maintained during 8 days. Water contents decreased according to the air supply capacity; 8.9%, 15.4%, 18.0% and 18.6% for T-1, T-2, T-3 and T-4. The weight ratios of T-1, T-2, T-3 and T-4 were reduced to 12.8%, 15.6%, 18.1% and 17.9%, respectively. The decreasing volumetric ratios of T-1, T-2, T-3 and T-4 were 18.0%, 21.0%, 22.3% and 22.0%. The oxygen discharge concentrations during composting were 12 ppm for T-1, T-2 and 9 ppm for T-3 and T-4. After composting, fertilizer components such as total nitrogen (TN) and phosphorous pentoxide ($P_2O_5$) were examined at each air supply capacity. Nitrogen contents of the T-1, T-2, T-3 and T-4 were 0.75%, 0.74%, 0.72% and 0.64%. Also, The contents of $P_2O_5$ were 0.35%, 0.40%, 0.38% and 0.42% for T-1, T-2, T-3 and T-4.

Construction and commissioning of a position-sensitive ionization chamber

Kwag, M. S.,Chae, K. Y.,Cha, S. M.,Kim, A.,Kim, M. J.,Lee, E. J.,Lee, J. H. 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.

<P>A position-sensitive ionization chamber has been constructed and commissioned at the Physics Department of Sungkyunkwan University to extract position information on incident charged particles for future nuclear reaction measurements. By utilizing the newly-designed position-sensitive anodes and the previously-commissioned portable gas-filled ionization chamber by Chae et al., position information on incident particles could be obtained. The device was tested with an Am-241 alpha-emitting source, and the standard deviation of the fitted Gaussian distribution was measured to be 1.76 mm when a collimator with a 2 mm hole was used.</P>

Development of system design and seismic performance evaluation for reactor pool working platform of a research reactor

Kwag, S.,Lee, J.M.,Oh, J.,Ryu, J.S. North-Holland Pub. Co 2014 Nuclear engineering and design Vol.266 No.-

The reactor pool working platform (RPWP) has been newly designed for an open-tank-in-pool type research reactor, and its seismic response, structural integrity, serviceability, and seismic margin have been evaluated during and after seismic events in this paper. The main important concept of the RPWP is to minimize the pool top radiation level by physically covering the reactor pool of the open-tank-in-pool type research reactor and suppressing the rise of flow induced by the primary cooling system. It is also to provide easy handling of the irradiated objects under the pool water by providing guide tubes and refueling cover to make the radioisotopes irradiated and protect the reactor structure assembly. For this concept, the new three dimensional design model of the RPWP is established for manufacturing, installation and operation, and the analytical model is developed to analyze the seismic performance. Since it is submerged under and influenced by water, the hydrodynamic effect is taken into account by using the hydrodynamic added mass method. To investigate the dynamic characteristics of the RPWP, a modal analysis of the developed analytical model is performed. To evaluate the structural integrity and serviceability of the RPWP, the response spectrum analysis and response time history analysis have been performed under the static load and the seismic load of a safe shutdown earthquake (SSE). Their stresses are analyzed for the structural integrity. The possibility of an impact between the RPWP and the most adjacent structure is investigated for the serviceability. The analysis results show that the maximum stress values of the base frame, guide tubes and refueling cover of the RPWP under the seismic event are within the specified code limits. It is confirmed that an impact does not take place under a seismic event. Also, the seismic margin of the RPWP is studied, and the seismic limit to sustain the structural integrity and serviceability is attained based on the deterministic and probability methods. Lastly, the hydrodynamic effect on the seismic performance of the RPWP is quantitatively investigated and from the result, an objective basis of the consideration of the hydrodynamic influence is acquired. Therefore, it is concluded that the newly devised RPWP is safely designed in that no damage to the structural integrity and serviceability, and a sufficient seismic margin is expected.

Construction and Commissioning of a Position-Sensitive Ionization Chamber

M. S. Kwag,채경육,차수미,김아람,M. J. Kim,E. J. Lee,J. H. Lee 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.10

A position-sensitive ionization chamber has been constructed and commissioned at the Physics Department of Sungkyunkwan University to extract position information on incident charged particles for future nuclear reaction measurements. By utilizing the newly-designed position-sensitive anodes and the previously-commissioned portable gas-filled ionization chamber by Chae et al., position information on incident particles could be obtained. The device was tested with an 241Am -emitting source, and the standard deviation of the fitted Gaussian distribution was measured to be 1.76 mm when a collimator with a 2 mm hole was used.

IT 융합 비즈니스 모델 사례 분석에 대한 연구

조수아(S. A. Cho),김민선(M. S. Kim),곽동기(D. G. Kwag),조성민(S. M. Cho),손웅희(W. H. Shon),이의진(E. J. Lee) 한국정밀공학회 2013 한국정밀공학회 학술발표대회 논문집 Vol.2013 No.5월

가변속 수냉각기의 계절별 용량제어 특성

백승문(S. M. Baek),김현우(H. W. Kim),곽진우(J. W. Kwag),문춘근(C. G. Moon),정석권(S. K. Jeong),윤정인(J. I. Yoon) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.4

This paper presents the characteristics of seasonal capacity control of variable speed water cooler. The experiment is set to find the degree of superheat obtaining the optimum cooling capacity, with the electronic expansion valve controlled by the variation of compressor speed maintaining the constant degree of superheat at the evaporator outlet. It is a preliminary study on the optimum control of the water cooler system using a variable speed compressor controlled by inverter. It is investigated that the distribution of high and low pressures on a system is checked with variation of electronic expansion valve open/close degree and outdoor temperature.