• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.143-153
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• 2014

This paper presents a novel application of LCC resonant converter for 60kW EV fast charger and describes development of the high efficiency 60kW EV fast charger. The proposed converter has the advantage of improving the system efficiency especially at the rated load condition because it can reduce the conduction loss by improving the resonance current shape as well as the switching loss by increasing lossless snubber capacitance. Additionally, the simple gate driver circuit suitable for proposed topology is designed. Distinctive features of the proposed converter were analyzed depending on the operation modes and detail design procedure of the 10kW EV fast charger converter module using proposed converter topology were described. The proposed converter and the gate driver were identified through PSpice simulation. The 60kW EV fast charger which generates output voltage ranges from 50V to 500V and maximum 150A of output currents using six parallel operated 10kW converter modules were designed and implemented. Using 60kW fast charger, the charging experiments for three types of high-capacity batteries were performed which have a different charging voltage and current. From the simulation and experimental results, it is verified that the proposed converter topology can be effectively used as main converter topology for EV fast charger.

• Progress in Superconductivity
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• 제4권1호
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• pp.86-89
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• 2002

In this paper, the design of a IMVA single-phase high temperature superconducting(HTS) power transformer with BSCCO-2223 HTS tapes is presented. The rated voltages of each sides of the transformer are 22.9 ㎸ and 6.6 ㎸, respectively The winding of 1MVA HTS transformer is consisted of double pancake type HTS windings, which have advantages of insulation and distribution of high voltage, and are cooled by subcooled liquid nitrogen of 65K. Four HTS tapes were wound in parallel for the windings of low voltage side and the four parallel conductors are transposed. The design of 1MVA HTS transformer, a shell type core made of laminated silicon steel plate is chosen, and the core is separated with the windings by a cryostat with a room temperature bore. The cryostat made of non-magnetic and non-conducting material and a liquid nitrogen sub-cooling system is designed in order to maintain the coolant's temperature of 65K. For electromagnetic analysis of 1MVA HTS transformer, a finite element method of an axis of symmetry is used. The maximum perpendicular component of magnetic flux density of pancake windings is about 0.15T. And through analyzing the magnetic field distribution, an optimal winding arrangement of 1MVA HTS transformer is obtained.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.396-401
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• 2004

In this paper, a 1MW HAWT(FIL-1000) rotor blade has been designed by BEMT(Blade Element Momentum Theory) with Prandtl's tip loss. Also, a 3-D flow and performance analysis on the FIL-1000 rotor blade has been carried out by using the 3-D Navier-Stokes commercial solver (CFX-5.7) to provide more efficient design techniques to the large-scale HAWT engineers. The rated power and itsapproaching wind velocity at design point (TSR=7.5) are 1MW and 9.99m/s respectively. The rotor diameter is 54.5m and the rotating speed is 26.28rpm. Airfoils such as FFA W-301, DU91-W-250, DU93-W-210, NACA 63418, NACA 63415 consist of the rotor blade from hub to tip. Recent CFX version, 5.7 was adopted to simulate 3-D flow field and to analyze the performance characteristics of the rotor blade. Entire mesh node number is about 730,000 and it is generated by ICEM-CFD to achieve better mesh quality The predicted maximum power occurringat the design tip speed ratio is 931.45kW. Approaching to the root, the inflow angle becomes large, which causesthe blade to be stalled in the region. Therefore, k-$\omega$ SST turbulence model was used to predict the quantitative flow information more accurately. Application of commercial CFD code to optimum blade design and performance analysis was proved to be more effective environment to HAWT blade designers.

• 플랜트 저널
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• 제11권1호
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• pp.30-38
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• 2015

본 연구는 최근 도입된 단기사채를 통해 한국수출입은행의 대외채무보증과 연계하여 자산유동화 구조에 접목한 자산담보부 단기사채의 금리를 추정하고 해외 투자개발형 민자발전사업의 수주 확대를 위한 프로젝트파이낸스의 한 방안으로 이용할 수 있는지에 대한 것이다. 회사채 신용등급 AA-부터 BBB+까지 건설사 자산담보부 단기사채와 비교한 결과, 자산 유동화 구조와 접목한 한국수출입은행의 대외채무보증부 자산담보부 단기사채는 금리 경쟁력이 있고, 프로젝트의 자기자본수익률이 개선됨을 확인할 수 있었다. 특히, 본 금융구조는 회사채 등급이 낮은 시공사에 적용할수록 더 높은 자기자본수익률 확보가 가능함을 알 수 있었다. 이를 통해, 경쟁력 있는 자산담보부 단기사채 금융조건은 수요 창출 및 수익성 확보는 물론 우리기업의 해외 투자개발형 민자발전사업 수주확대에 기여할 것으로 기대된다.

• 한국전자통신학회논문지
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• 제13권4호
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• pp.757-764
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• 2018

본 논문은 공조시스템에 사용되는 1마력급 2상 BLDC 팬모터의 설계 및 구현에 관하여 기술한다. 본 연구에서 구현한 BLDC 모터는 수명 및 내구성이 우수한 무정류자 모터방식이며 2상 전원에 의해 구동된다. 공조시스템에 사용되는 모터의 가장 중요한 목표사양은 정격운전점에서 높은 효율을 갖는 것이다. 이를 위해 BLDC 모터의 고정자 형상과 회전자 자석의 설계를 수행하고 구동을 위한 제어회로를 설계하였다. BLDC 모터는 모터부와 제어부 그리고 전원부가 일체화된 구조를 갖는다. BLDC 모터의 특성계산을 위해 유한요소해석을 사용하였으며 시제품의 제작 및 성능시험을 실시하여 설계결과의 적합성을 확인하였다.

• 조명전기설비학회논문지
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• 제23권12호
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• pp.58-65
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• 2009

최근 한국철도기술연구원이 개발한 한국형 틸팅열차(TTX) "한빛 200"은 현재 호남선, 중앙선, 충북선 그리고 태백선에서 시험 운행 중에 있다. 본 논문은 TTX가 기존선로에서 시험 운행하는 동안 TTX에 공급되는 전압을 계측 하여 각 기존선로에서 공급하는 전압의 상태를 분석하였다. TTX에 공급되는 전압을 직접 계측하기 위해 TTX의 판토그래프 밑단인 부분에 PT를 설치하여 변압기 1차측 전압을 계측하였다. 정확한 분석을 위해 계측 시 TTX외의 다른 열차와 교차 상황과 주변상황에 대해 기록하였으며, CBEMA 커브를 이용하여 가선전압 상태에 대한 분석을 하였다. 그 결과 호남선, 중앙선, 태백선 모두 정격전압(25[kV])의 110[%]이상의 전압이 200[s]이상 공급되는 구역도 있었으며 빈번하게 110[%]를 초과하고 있는 것으로 분석됐다. 특히 태백선의 가선전압의 상태가 가장 좋지 않은 것으로 분석됐다. 이렇게 가선전압 분석결과는 앞으로 중앙선 및 태백선에 상용화될 TTX의 동력장치 및 전력변환장치를 안정화하는데 도움이 될 것으로 사료된다.

• 한국기계가공학회지
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• 제18권10호
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• pp.8-19
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• 2019

In this study, the spray pattern of a centrifugal fertilizer distributor with two shutter holes was analyzed and an effective driving width that satisfies proper spray uniformity was derived. The centrifugal fertilizer distributor was mounted on a tractor with a rated power of 23.7 kW and static and dynamic spray pattern tests were performed according to the standard procedure proposed by the American Society of Agricultural and Biological Engineers Standard ASAE S341.5. The height of the fertilizer distributor was 80 cm from the ground and the PTO (power take-off) shaft speed of the tractor was fixed at 540 rpm. The fertilizer scattered in space was collected using 275 evenly spaced collectors at shutter opening ratios of 25%, 50%, 75%, and 100%. The spray pattern was analyzed via the amount of sprayed fertilizer at each collector location and the coefficient of variation was used as an indicator of spray uniformity. Using the analyzed spray pattern, the effective driving width that satisfied less than 15% of the coefficient of variation was derived for different tractor driving patterns (race track mode, back and forth mode). From the results, spray uniformity increased as the shutter opening ratio decreased. The largest effective driving width was 8 m at a shutter opening ratio of 25% for both driving patterns.

• 한국건축친환경설비학회 논문집
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• 제12권6호
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• pp.669-679
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• 2018

Energy consumption savings in buildings should be reviewed in diverse areas such as air conditioning system and lighting responsible for cooling and heating, and energy management systems such as BAS (Building Automation System) and BEMS (Building Energy Management System) are introduced to improve energy consumption efficiency and to promote economic control of related facilities by integrated management of energy generated and consumption in buildings. The measured building of this study uses regenerative geothermal system. Measured values of heat pump and system COP were 4.7 and 4.2 respectively, and they were found to be higher 11.9% and 23.5% than rated values. As a result of analyzing the air conditioning and lighting energy from the first floor to the fourth floor performing the air conditioning, the second and third floors, which have a high frequency of use, are compared with the first and fourth floors 50% higher energy consumption ratio. On the other hand, the general heat storage system uses the nighttime power of the previous day to store heat and use it the next day. The total number of days of abnormal operation during the summer season is 61 days. The electricity cost corresponding to the abnormal operation is 1,840,641 KRW, and the normal operation using the nighttime power is 1,363,561 KRW, which is difference of 477,080 KRW, 35% increase in cost. We will utilize it as the main data of BEMS through analysis of winter operation characteristics as well as summer operation characteristics.

• 한국가스학회지
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• 제25권1호
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• pp.40-47
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• 2021

본 연구에서는 화재폭발 사고의 원인 규명을 위하여 다양한 시험 장비를 사용하여 유기과산화물의 일종인 터셔리부틸퍼옥시말레이트(TBPM)의 분해 및 폭발 위험성을 조사하였다. 시차주사열량(DSC) 분석결과, TBPM의 순간동력밀도(IPD)는 26,401 kW/ml로서 NFPA 반응성지수(Nr)가 4로 분류되었다. 또한 발열량과 개시온도 측정값을 이용한 폭발전달성(EP)과 충격감도(SS)는 양의 값을 나타내며 위험성이 있는 것으로 예측되었으며, 평가 장비를 활용한 실험적 결과로부터 충격감도와 마찰감도는 각각 4급 및 5급으로 평가되었다. 압력용기시험에서는 USA-PVT No.가 4로 분류되어 자기반응성물질에 해당되는 것으로 나타났다. 연소속도에 대한 조사 결과로부터 TBPM은 167 mm/sec의 연소속도를 나타내며 인화성고체 분류2에 포함되는 것으로 평가되었다.

• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.46-53
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• 2022

RIn this study, a test tractor that could measure various types of agricultural operational loads was developed, and its performance was verified. This tractor could be used to measure the load generated during agricultural work and convert the related data into a database. A test tractor was developed using an 80-kW-rated load tractor, and it could measure various types of field test data, such as engine torque and rpm, wheel torque, PTO(power take-off) torque, hexometer, IMU/INS sensor, steering angle sensor, hydraulic pressure, and flow sensor data. To verify the developed test tractor, a verification test using an agriculture rotavator was performed. The test conditions were L1, L2, and L3 based on the tractor's main and sub-transmission stages, and stages 1 and 2 were selected as the PTO. In a comparison of the analyzed test data, similar tendencies in the test results of this research and other research (Kim's research) were seen. Through this, the developed test tractor was verified. In the future, we plan to conduct research on the tractor developed in this study using various attached working machines.