• 한국초전도저온공학회지:초전도와저온공학
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• 제20권2호
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• pp.15-22
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• 2018

The present article briefly overviews the plan for a new project on joint technology for HTS wires/cables and describes the development plan for the world's highest field NMR magnet, which is a major development item in the project. For full-fledged social implementation of superconducting devices, high temperature superconducting (HTS) wire is a key technology since they can be cooled by liquid nitrogen and they can generate a super-high magnetic field of >>24 T at liquid helium temperatures. However, one of the major drawbacks of the HTS wires is their availability only in short lengths of a single piece of wire. This necessitates a number of joints being installed in superconducting devices, resulting in a difficult manufacturing process and a large joint resistance. In Japan, a large-scale project has commenced, including two technical demonstration items: (i) Development of superconducting joints between HTS wires, which are used in the world's highest field 1.3 GHz (30.5 T) NMR magnet in persistent current mode; the joints performance is evaluated based on NMR spectra for proteins. (ii) Development of ultra-low resistive joints between DC superconducting feeder cables for railway systems. The project starts a new initiative of next generation super-high field NMR development as well as that of realization of better superconducting power cables.

• 한국가스학회지
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• 제10권3호
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• pp.41-47
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• 2006

가스배관, 상수관, 송유관 등의 지중 매설배관이 직류 전기철도와 인접해 있는 경우, 전기철도 시스템의 귀선 회로로 사용되는 레일에서 누설되는 표유전류에 의해 이들 금속배관에는 전기적 부식, 즉 전식이 발생할 수 있다. 전식에 의한 집중 부식은 전기방식으로 보호되는 배관에 있어서도 지속적인 재료의 열화와 이에 따른 파손을 일으킬 수 있어 대형사고로 발전할 소지를 가지고 있다. 국내에서는 이러한 표유전류에 대한 대책으로 배관과 레일을 전기적으로 접속하는 배류법이 적용되고 있는데 특히 가스배관을 중심으로 한 강제배류법의 급속한 증가에 의해 간섭문제가 매우 복잡해지고 있다. 본 논문에서는 직류전기철도시스템과 매설배관 사이의 전기적 간섭 문제를 서울과 부산 지역에서 수행한 현장 실태조사의 결과를 통해 살펴본다.

• 조명전기설비학회논문지
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• 제20권1호
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• pp.41-47
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• 2006

최근 전기철도에 고속화 기술이 적용되고 열차 구동장치 및 제어계통에 전력용 반도체 소자가 사용되고 있으며, 전기철도 구동시스템의 주요 구성장치인 인버터와 컨버터의 동작을 제어하는 전력전자 소자의 이용은 고조파를 발생의 원인이 된다. 이러한 고조파는 통신장해 및 전류, 전압의 전력품질 저하 등 여러 가지 문제를 발생시킨다. 따라서 본 논문에서는 인천 국제공항에 설치되고 있는 경전철 전력설계의 전력시스템 평가 및 개발을 통해 상위 계통에 미치는 영향 및 전력시스템에서 발생할 수 있는 장애 요인을 사전에 예측 계산하여 이에 대한 대책을 마련하여 전력품질 향상에 목적이 있다. 인천 국제공항청사 내의 전력시스템의 전력품질 문제 접근에 있어 경전철이 운행될 경우 발생할 수 있는 여러 문제 중 특히 전압강하 및 전압불평형에 영향을 미치는 고조파 발생에 대해 분석하였다. 고조파 분석은 IEEE 519-1992(IEEE 141-1993과 동일) 기준에 의거하여 행하였다. 또한 인천 공항청사의 운행되는 경전철은 동적 전력시스템 해석 프로그램인 PSCAD/EMTDC 모델링하고 이의 시뮬레이션 결과를 이용하여 고조파 분석을 하였다.

• 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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.332-338
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• 2008

This paper handles, implementation of multiple access bidirectional serial communications protocol using two common DC power lines, whict are power supply and ground, connecting multiple devices. Communication between the host and the multiple clients are performed using unique packet data with device ID unique to each devices connected on the common power lines. Host initiates data communications by transmitting command packet to the designated client with the client's ID and the client responds by transmitting response packet to the host and in this way, multiple clients and host exchange the packet through the common power lines. The normal voltage of the power communication line maintains 24V corresponding to level 1 and the host drops the voltage to 12V on sending level 0 signal, also the clients normally keeps the line voltage to 24V use pull-down circuit to drop the voltage to 12V on sending level 1 signal. Power supply originates from the host, the host senses the voltage level of the power communication lines and when the clients activates pull down circuit to send level 0 signal and the voltage drops to 12V, the hosts switches power source from 24V to 12V. Also, when clients deactivate pull down circuit to send level 1 signal, the host senses the voltage increase and switches the power source from 12V to 24V. Experimental circuit is designed with one hosts and four clients and verified the power line voltage switching operation depending on the data signal levels on the power line. The proposed research result can be applied to two wire power communications system with one host and multiple low current consumption clients.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2357-2364
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• 2011

Diesel locomotive operates the generator with the power from the diesel engine, and it consists of the typical serial-hybrid system which operates the train wheels by converting its generated electric energy into the torque of DC (or AC) motor. However, the technology of locomotives is only focused on trains' controlling power generation mechanism. Hence, it is a current issue that the efficiency of its engine and its generator is relatively lower than that of auto vehicles'. Particularly, since there are no proper equipment to measure the amount of fuel which is essentially necessary for the efficient use of fuel, it is not easy to confirm the instant amount of fuel use as well as the exact average fuel consumption per an hour. Due to those difficulties, it is urgent to develop the device that measures the fuel consumption. Plus, this use of the developed measuring device allows the various and useful analysis relating to the fuel consumption, and this could lead to establishing the efficient driving pattern regarding to fuel saving. This device consists of two flux (fuel level) measuring censors, MCU for calculating the measured values, the information recorder for saving measured values, and the display device for indicating the fuel amount consumed during driving.

• 전기학회논문지P
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• 제60권3호
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• pp.110-113
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• 2011

Platform Screen Door, PSD, is a device that seeks to prevent accidents with regards to falling off the platform and getting trapped between the trains, achieve improvements on the cleanliness of the air, address the accessibility issue of the disabled and the elderly and provide fresher environment on the platform in general. This is achieved by preventing health hazards and accidents from occurring through installation of fixed and moving doors between rail, tram and subway platforms and the railway. Domestic firms have achieved domestic production to a large degree in various Control Units including the Overall Control Unit and RF devices through investments in technology. Despite this, full domestic production of the core of the PSD system, Door Control Unit, DCU, is not yet achieved, having to install PSDs in a relatively short period of time. Currently, controllers with DC motors are developed for installation or one is faced with having to import foreign produced controllers. In this research, the control unit prototype using the BLDC motor was domestically produced. The performance of the control unit was rigorously tested through installation on Eun-Ha Rail on Wol-Mi Island.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.51-56
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• 2007

Pantograph of the electric train is the important part receiving current by adhereing contact wire. Wearing rate of pantograph or contact wire is changed by the type of pantograph and material of adhering part. In special, the weather influences the relative wearing rate and wearing type of pantograph Slider and Contact wire with steep wearing in arc and life cycle of pantograph slider. Presently, the weather causes side-wearing and over-wearing of pantograph slide installed in electric train. So it is difficult to manage and operate the electric train. Although the quality of slide using in line4 vehicle was finished the test in line 2 vehicle experimentally, it has to apply after pantograph is installed in some electric trains and check the influence in it and contact wire. It is because line4 section is very different from line2 section. Experimental application is the sequence to certify the safety and abrasion resistance importantly by enlarging experimental application with increase of the experimental electric train. The lenth of line4 in Seoul Metro is 71.5[km]. It is long section. The line is mixed DC 1,500[V] section and AC 25,000[V] section. It has underground section of 41.5[km] and ground section of 30[km]. Ground section is about 42% and receives much influence in the rain during the rainy season. After experimental application we found that this pantograph slide has twice as much abrasion resistance despite a little deviation and found the occurrence probability of arc and side-wearing is decreased considerably.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.405-410
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• 2004

There are two types of noises in running the rail vehicle. The one is periodic by electric motors, dehumidifiers, and dusting machines. And the other is aperiodic squeal noise by the frictions between the wheels and the rail or the disks and pads. The periodic noises in rail vehicle have been reduced by changing DC motors to AC motors with silencers, and by improving the lubricants. However, almost nothing relating a periodic noise has been studied. In this paper, the experimental methods were applied to understand phenomena of the squeal noise, which was occurred by the friction variation due to aperiodic stick and slip with low repeatability in the process of dry friction of the disk and the pad when a rail vehicle was being braked. By the experimental acoustic test, it was found the specific frequencies relating the squeal noise. And by modal testing, it was measured the resonant frequencies in the disk and the pad-plate which were the components of the braking system, and in the whole braking system, and it was found the specific frequencies having the effects on the squeal noise.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 추계학술대회
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• pp.34-36
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• 2019

본 논문은 교류전기철도의 불평형 부하로 인해 야기되는 3상 계통 전력의 불평형 특성을 저감하기 위한 제어 알고리즘을 제안하였으며, 전력보상장치 설계 및 이를 적용한 실험을 통해 성능을 검증하였다. 전기철도 시스템과 동일하게 3상 전압을 2개의 단상 전압으로 변환하는 스코트 변압기를 적용하였으며, M상과 T상 출력 단에 부하 및 3레벨 백투백 컨버터가 연계되어 구성된다. 백투백 컨버터는 M, T상의 불평형 부하 간 발생하는 유효전력의 차이를 실시간으로 감시하고 양방향 특성을 이용해 전력을 보상하는 역할을 수행한다. 백투백 컨버터의 유효전력은 동기좌표계 PI 제어를 통해 수행되며, DC 링크 전체 전압 및 밸런싱 제어는 시스템의 응답성 향상을 위해 M, T상 컨버터가 공동으로 분담하여 제어한다. 제안된 전력보상장치의 성능 확인을 위해 M상 5kW, T상 1kW 불평형 부하가 연계된 조건에서 시뮬레이션 및 실험을 진행하였으며, 실험 결과 전력보상장치의 동작 후 3상 전류의 불평형률이 65.04%에서 6.38%로 58.66% 저감되는 것을 통해 본 논문에서 제안하는 전력보상장치의 우수한 성능을 검증하였다.