• 한국산학기술학회논문지
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• 제12권9호
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• pp.4083-4094
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• 2011

전기식 파워 스티어링(EPS)은 유압식 파워스티어링에 비해 연비가 높고 스티어링 느낌이 좋으며 체적이 작으므로 자동차에 많이 적용되고 있다. 몇 년 전까지 대부분의 EPS 시스템에는 제어가 쉽고 하드웨어 구조가 간단한 영구자석 DC 모터가 주로 적용되었으나 최근에는 효율이 높고 수명이 긴 BLAC 모터가 적용되고 있다. 본 논문에서는 최근에 발표된 논문들을 기초로 EPS 시스템의 구조 및 BLAC 모터와 제어기술에 대해 고찰한다. 또한 스티어링 느낌을 좋게 하기 위한 토크리플 저감 및 안전을 위한 고장검출 알고리즘에 대해서도 검토한다.

• 기술사
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• 제38권5호
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• pp.10-22
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• 2005

This paper describes possible solutions among others how to transmit the power technically for the South Korea's 'important proposal', offering 2 million kilowatts of electric power to North Korea. Two authors present their personal opinions respectively; Mr. C. I. Nahm in the first part deals the subject on "the Status of Power Industry in DPRK and Proposed Scheme to supply 2GW Electric Power to DPRK" and in the second part Dr. Rimtaig Lee expresses his ideas on 'the Mid-Long Term Plan to solve the Power Shortage in DPRK'.

• 전기학회논문지
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• 제56권12호
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• pp.2084-2090
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• 2007

The DGA (Dissolved Gases Analysis) technique has been widely using for fault diagnosis of the power transformers. Some electric power utility company establishes the criteria of DGA to improve reliability, because of difference of operation environment and design of power transformer. In this paper, we introduce intelligent diagnosis system for DGA result of KEPCO (Korea Electric Power Cooperation). This system can classify patterns type of gases ratio that frequently occurs in recent result of gases analysis using Fuzzy Inference. The classification of Patterns let us know that major causes of gases generation based on type of patterns. Finally, Neural Network based on patterns diagnose transformer. NN was trained using result data of DGA of actually faulted transformers recently. Result of intelligent diagnosis system is right well in comparison with actual inner inspection of transformers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기설비전문위원
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• pp.166-168
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• 2007

The DGA (Dissolved Gases Analysis) technique has been widely using for fault diagnosis of the power transformers. This technique has a high reliability than other techniques. KEPCO (Korea Electric Power Cooperation) has been using DGA technique since KEPCO established the criteria of DGA in 1985. In this paper, we introduce the DGA criteria of KEPCO and analyze the result of DGA. Also we introduce the cases of thoroughgoing inspection of the power transformers caused by DGA and compare the judgment of DGA with the result of throughgoing inspection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권2호
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• pp.635-656
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• 2019

In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.

• 전기학회논문지
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• 제60권5호
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• pp.1073-1077
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• 2011

The breaking capacity of circuit breakers could be no more increased in the electric power system. This is because the fault current increases due to continuous increases in electric power demand and facilities. To solve the problem, it is necessary to come up with an alternative. The superconducting fault current limiter (SFCL) has received an attention among various alternatives. The SFCL effectively reduce a fault current in cooperation with a power circuit breaker. A various types of the SFCL are suggested and a study on them have been progressed. As a result of it, the SFCL can be applyed to the electric power system in the near future. But, a study on recovery behaviors of the SFCL is not enough for applying to the electric power system. If the superconducting elements do not completely recover to the superconducting state after fault operation, it might be a breakdown of the superconducting elements due to heavy power burden and it gives an bad influence on the working of other electric devices. Additionally, the distribution power system has reclosing operation such as open-0.3sec-closed/open-3min-closed/open procedure. So we need to study more about improvement of the recovery behaviors of the SFCL. In this paper, we analyzed the recovery behaviors of a flux-coupling type SFCL according to reclosing operation when a single line-to-ground fault occurred and we compared recovery behaviors of the SFCL with and without a neutral line between secondary reactors and superconducting elements. Also, the flux-coupling type SFCL has advantageous for increases of capacity by controlling the variation in turn ratios between two reactors. Consequently, when the number of turns of the secondary reactors increased, the power burden of the superconducting elements was bigger due to the increase of impedances of the secondary reactors. To distribute the power burden, two superconducting elements connected in series and the balanced quenching of the superconducting elements was induced by connecting a neutral line.

• 한국산학기술학회논문지
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• 제12권8호
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• pp.3360-3365
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• 2011

본 논문은 힘 보조형 휠체어에 있어 힘 센서 없이 사용자의 구동 의지를 측정하는 방법과 이를 통한 차량제어 방법을 제시한다. 이를 위해 먼저 모터의 수학적 모델을 이용하여 사용자의 구동 의지력을 추정하는 알고리즘을 도출한다. 이후 도출된 외력을 기반으로 사용자가 원하는 차량 속도 및 방향을 추정한다. 이를 토대로 차량의 이동량을 결정하고 차량이 이에 따라 구동되도록 알고리즘을 구성하였으며 이를 시뮬레이션을 통해 검증하였다.

• Asian Journal of Innovation and Policy
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• 제8권1호
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• pp.31-57
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• 2019

Myanmar's current power situation remains severely constrained despite being richly endowed in primary energy sources. With low levels of electrification, the demand for power is not adequately met. Cooperation in energy has been a major focus of future initiative for all developed and developing nations. If we want to solve climate change, and change our energy infrastructure, we need to be innovative and entrepreneurial in energy generation. This paper will help us in examining Bayesian MCMC Analysis for the parameters estimation among the arrival rates of disaster occurrences, firm's expected income-based electricity tariffs, and estimated R&D investment expenses in new energy industry. Focusing on Japan's electric power business, we would like to search the potential for innovative initiatives in new technological energy industry for the regional development and ecological sustainability in Myanmar.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2002년도 추계학술발표논문집
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• pp.141-144
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• 2002

Recently, the operation of power distribution systems has become more difficult because the peak demand load is increasing continuously and the daily load factor is getting worse and worse. Also, the consideration of deregulation and global environment in electric power industry is required. In order to overcome these problems, a study on the planning and operation in distribution systems of dispersed generating sources such as fuel cell systems, photovoltaic systems and wind power systems has been performed energetically. This study presents a method for determining an optimal operation strategy of dispersed co-generating sources, especially fuel cell systems, in the case of both only electric power supply and thermal supply as well as electric power supply. In other words, the optimal operation of these sources can be determined easily by the principle of equal incremental fuel cost and the thermal merits is evaluated quantitatively through Kuhn-Tucker's optimal conditions. In order to select the optimal locations of those sources, an priority method using the comparison of total cost at the peak load time interval is also presented. The validity of the proposed algorithms is demonstrated using a model system.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5392-5395
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• 2013

환자 및 노약자 이동에 중요한 역할을 하고 있는 수 전동휠체어의 핵심부인 구동부를 새롭게 설계했다. 구동부는 고속모터와 다단기어 치형을 설계적용하고, 굽힘강도와 면압강도를 고려해 큰 추진력을 얻을 수 있도록 성능을 검증하였다. B-Type의 마찰판식 클러치 전자식 브레이크(다판 방식의 무여자 작동형)를 동 축상에 설치해, 큰 토크에도 급격한 제동이 가능하도록 했다. 본 연구에 설계된 다단치차 감속기를 수 전동휠체어 구동장치에 사용하므로서, 소형화, 경량화를 이루고 구동 효율이 기존제품보다 30% 향상된 구동부를 구성할 수 있었으며, 보수 및 관리의 용이성을 함께 추구했다.