• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.527-533
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• 1998

An optimized PWM switching strategy for an induction motor voltage control is developed and demonstrated. Space vector modulation in voltage source inverter offers improved DC-bus utilization and reduced commutation losses, and has been therefor recognizedas the perfered PWM method, especially in the case of digital implementation. Three-phase invertor voltage control by space vector modulation consists of switching between the two active and one zero voltage vector by using the proposed optimal PWM algorithm. The prefered switching sequence is defined as a function of the modulation index and period of a carrier wave. The sequence is selected by suing the inverter switching losses and the current ripple as the criteria. For low and medium power application, the experimental results indicate that good dynamic response and reduced harmonic distortion can be achieved by increasing switching frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.685-688
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• 1998

In this research project, two aspects of small signal stability are studied: improvement in Hessenberg method to compute the dominant electromechanical oscillation modes and siting FACTS devices to damp the low frequency oscillation. Fourier transform of transient stability simulation results identifies the frequencies of the dominant oscillation modes accurately. Inverse transformation of the state matrix with complex shift equal to the angular speed determined by Fourier transform enhances the ability of Hessenberg method to compute the dominant modes with good selectivity and small size of Hessenberg matrix. Any specified convergence tolerance is achieved using the iterative scheme of Hessenberg method. Siting FACTS devices such as SVC, STACOM, TCSC, TCPR and UPFC has been studied using the eigen-sensitivity theory of augmented matrix. Application results of the improved Hessenberg method and eigen-sensitivity to New England 10-machine 39-bus and KEPCO systems are presented.

• Journal of Information Processing Systems
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• 제13권1호
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• pp.95-103
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• 2017

The PCI Express is a widely used system bus technology that connects the processor and the peripheral I/O devices. The PCI Express is nowadays regarded as a de facto standard in system area interconnection network. It has good characteristics in terms of high-speed, low power. In addition, PCI Express is becoming popular interconnection network technology as like Gigabit Ethernet, InfiniBand, and Myrinet which are extensively used in high-performance computing. In this paper, we designed and implemented a evaluation platform for interconnect network using PCI Express between two computing nodes. We make use of the non-transparent bridge (NTB) technology of PCI Express in order to isolate between the two subsystems. We constructed a testbed system and evaluated the performance on the testbed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.365-368
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• 1998

In this research project two aspects of small signal stability are studied: improvement in Hessenberg method to compute the dominant electromechanical oscillation modes and siting FACTS devices to damp the low frequency oscillation. Fourier transform of transient stability simulation results identifies the frequencies of the dominant oscillation modes accurately. Inverse transformation of the state matrix with complex shift equal to the angular speed determined by Fourier transform enhances the ability of Hessenberg method to compute the dominant modes with good selectivity and small size of Hessenberg matrix. Any specified convergence tolerance is achieved using the iterative scheme of Hessenberg method. Siting FACTS devices such as SVC, STACOM, TCSC, TCPR and UPFC has been studied using the eigen-sensitivity theory of augmented matrix. Application results of the improved Hessenberg method and eigen-sensitivity to New England 10-machine 39-bus and KEPCO systems are presented.

• 동력기계공학회지
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• 제20권4호
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• pp.69-74
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• 2016

Recently, in order to meet the stricter emission regulations, the proportion of after-treatments for vehicle and vessel is increasing gradually. The purpose of this study is to investigate the de-$CH_4$ characteristics of NGOC in front of proposed combined system according to additive catalyst and support ratio. In the case of Pd addition, the de-$CH_4$ performance of 2Pt-2Pd-3MgO/$Al_2O_3$ NGOC was improved by approximately 10 to 20% for the HC components. The de-$CH_4$ performance of 2Pt-2Pd-3Cr-3MgO/$Al_2O_3$ NGOC was higher compared to five kinds of NGOC catalysts, because Cr particle was smaller and dispersion of Pd was increased. The NGOC(Zeolite:$Al_2O_3$(80%:20%)｝catalyst according to support ratio, was improved performance at low temperature region on CO and NO conversion rate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.371-373
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• 2005

An enhancement for a transmission and substation equipment in power system make the system impedance to be lower. In principle, if the system impedance become low, system stability will be better, but the fault current become very higher. It is a very big problem for CB operating. As a fact of CB operating performance, high amplitude of the fault current may cause CB operation failure because of exceeding standard value in TRV. So we simulated TRV by using the EMTP. Generally there are two types of TRV in actual power system. One is short line fault, the other is bus terminal fault. In this paper, we simulated the TRv at short line fault as installed current limit reactors to reduce fault current in 345kV ultra-high voltage system. Short line fault is caused from single line fault in transmission line.

• Journal of information and communication convergence engineering
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• 제11권1호
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• pp.7-11
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• 2013

Wearable computer systems use the wireless universal serial bus (WUSB), which refers to USB technology that is merged with WiMedia physical layer and medium access control layer (PHY/MAC) technical specifications. WUSB can be applied to wireless personal area network (WPAN) applications as well as wired USB applications such as PAN. WUSB specifications have defined high-speed connections between a WUSB host and WUSB devices for compatibility with USB 2.0 specifications. In this paper, we focus on an integrated system with a WUSB over an IEEE 802.15.6 wireless body area network (WBAN) for wireless wearable computer systems. Due to the portable and wearable nature of wearable computer systems, the WUSB over IEEE 802.15.6 hierarchical medium access control (MAC) protocol has to support power saving operations and integrate WUSB transactions with WBAN traffic efficiently. In this paper, we propose a low-power hibernation technique (LHT) for WUSB over IEEE 802.15.6 hierarchical MAC to improve its energy efficiency. Simulation results show that the LHT also integrates WUSB transactions and WBAN traffic efficiently while it achieves high energy efficiency.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.11-13
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• 2019

This paper proposes a novel high step-up non-isolated DC-DC converter, suitable for regulating dc bus in various inherent low voltage micro sources especially for photovoltaic (PV) and fuel cell sources. This novel high voltage Non-isolated Boost DC-DC converter topology is best replacement, where high voltage conversion ratio is required without the transformer and also need continuous input current. Since the proposed topology utilizes the stack-based structure, the voltage gain, and the efficiency are higher than other conventional non-isolated converters. Switches in this topology is easier to control since its control signal is grounding reference. Also, there is no need of extra gate driver and extra power supply for driver circuit, which reduces the cost and size of system. In order to show the feasibility and practicality of the proposed topology principle operation, steady state analysis and simulation result is presented and analyzed in detail. To verify the performance of proposed converter and theoretical analysis 360W laboratory prototype is implemented.

• 한국ITS학회 논문지
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• 제16권2호
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• pp.161-170
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• 2017

발리스는 열차의 안전한 운행을 위하여 철도의 레일 사이에 설치하여 운영하는 장치로, 텔레그램이라 칭하는 정보(거리 구배 속도 임시 속도제한 등의 가변정보)를 무선으로 통과하는 열차에 전송하는 기능을 갖는다. 본 연구는 이에 필요한 DBPL 인코더의 설계에 대한 것이다. 일반적으로 발리스를 위한 DBPL 인코더는 전용 ASIC이나 FPGA를 통하여 구현하고 있으나, 본 연구에서는 범용의 저전력 마이크로컨트롤러(STM32L4 Series)를 활용하여 설계하였다. 본 연구의 DBPL인코더는 펌웨어 방식의 논리적 1차 처리 수단과 마이크로컨트롤러 내장 SPI Bus 등을 이용한 물리적 출력수단으로 구분하여 설계하였다. 본 연구의 DBPL 인코더는 유로발리스 표준에서 요구하는 564.48Kbps의 속도로 동작 가능함을 확인하였다.

• 한국항행학회논문지
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• 제20권1호
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• pp.86-92
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• 2016

최근 사람이 다수 붐비는 지역에 스마트 폰이나, 태블릿 등을 바로 충전할 수 있는 태양광 모듈이 설치되어 서비스를 제공하고 있다. 하지만 설치비용이 높아 이용인원이 적은 지역에 설치 할 경우 비용측면에서 부담이 되며, 협소한 지역에는 설치가 어려운 문제점이 존재한다. 본 논문에서는 이와 같은 문제를 해결하기 위해 국가에서 제공하는 데이터와, 실제 환경에서 수집한 데이터를 이용하여 각 지역에 해당 서비스를 제공받는 사람에 대한 정보를 분석 한 후 대기시간 및 태양광 충전시간을 고려하여 환경에 맞는 최적의 전력을 수집 및 제공하는 시스템을 제안하였다. 실험결과 수집전력이 충전전력량보다 상회하여 충전이 지연되지 않았으며, 약 95분경에 스마트 폰의 전력을 모두 충전할 수 있음을 확인하였으며, 버스 대기시간인 10분에서 20분 사이에 스마트 폰이 한 대일 경우 약 50%가량을 충전할 수 있으며, 여러 대일 경우 약 20%가량을 충전할 수 있음을 확인하였다.