• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.94-101
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• 1999

In this paper the problems associated with the switching surge of PWM inverter devices were analysed. As the application of ASD for efficient speed control of AC rmtors is increased, so is the rrntor and ASD-related failure increased. In the industrial rmtor awlications, the introduction of PWM drives can sometmes cause insulation breakdown between the phase windings due to high transient voltage peak. The motor cable length combined with the high switching frequency becomes more sensitive issue for proper drive operation. Effects of the cable length and high switching frequency influence both on rmtor and inverter. When the insulation level of rmtor winding is low, the failure probability caused by high peak voltage and fast voltage rise times(dv/dt) is high. Voltage refloctions are simulated far rmtor capacities, ASD and rise times and are presented graphically. The filtering techniques are discussed to reduce the rmtor terminal overvoltage and dv/dt in inverter fed AC rrntor drive systems. We confirmed that the lower motar capacity and rmtar insulation level, the shorter switching time and cable length and the higrer the probability of insulation breakdown .kdown .

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.186-191
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• 2004

전력계통에서 역률개선을 위해 사용하는 전력용 콘덴서(이하 SC bank)는 전력계통의 운전상 전압 제어와 역율개선이라는 두가지 측면에서 매우 중요한 전력설비이다. 또한 최근에 전력산업 구조조정에 의해 발전분야가 분할되는 시점에서 SC bank의 역할의 중요성이 강조되고 있다. 본 논문에서는 SC의 고장원인이 무엇인지를 현장조사를 통해 수행하였다. 그 결과 SC bank를 구성하고 있는 리액터, 콘덴서, PT, 혹은 CT 흑은 방전코일의 열화원인이 대부분 차단기의 투입서지와 차단서지에 의해 발생되고 있음을 확인하였다 또한 기존의 보호시스템은 SC Bank의 보호에 적합하지 않음을 검토하였다 차단기 서지에 대한 대책으로는 투입시 전압영점투입과 중성점 저항기의 취부로 투입서지 및 차단서지를 효과적으로 감소되는 현상을 모의와 현장실측을 통해 확인하였다. 또한 기존의 보호방식이 과전류와 과전압 부족전압 혹은 CT와 PT를 이용한 차동방식에 의해 셀의 경련변화를 감지하고 있으나 이 경우 보호맹점이 존재하게 됨을 검토하였다. 이러한 보호상의 문제점을 보완하는 방법으로 SC bank는 임피던스가 늘 일정하는 점에 착안하여 전압과 전류를 이용하여 임피던스의 변화량을 감시하고, 또 한가지 방법은 SC bank의 운전특성상 무효전력만을 발생시킨다는 점에 착안하여 만일 유효전력 성분이 SC bank에서 감지된다면 소자의 이상이나 비정상적은 전류경로가 된다는 결론에 도달하고 유효전력감시를 통한 SC bank의 열화감지가 가능하다는 결론에 도달하였다. 본 논문에서 제안한 3가지의 방법, 즉, 첫째 영점투입차단기 채택, 둘째, 중성점 저항기의 도입, 셋째 새로운 보호방식에 의한 기존의 보호맹점의 보완을 제안하였다. 위의 새로운 제안을 현장에 적용하는 경우 제작사의 제작불량을 제외한 운전상의 SC bank의 문제점 및 고장빈도는 현저히 감소하게 될 것으로 사료된다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1183-1190
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• 2018

The environmental regulations are being strengthened all over the world, and the introduction of electric vehicles are actively being considered to cope with them effectively. It is essential to establish a charging infrastructure, which is an essential element of electric vehicle distribution. In this paper, power line communication technology essential for smart charging infrastructure is studied. A control board capable of achieving a physical layer speed of 10Mbps and a TCP/IP layer of 4.5Mbps, which conforms to the ISO/IEC 15118 international standard, and a control board mounted on the board and compliant with international standards. We have developed a software solution to perform functions for linking. In addition, in order to be applied to the combo-type DC fast charger, the hardware was designed to meet the industrial environment standard and the V2G communication module was developed by integrating it with the software solution.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.5
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• pp.95-108
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• 2011

Smart Grids are intelligent next generating Electric Power System (EPS) that provide environment-friendliness, high-efficiency, and high-trustworthiness by integrating information and communication technology with electric power technology. Smart grids help to supply power more efficiently and safely than past systems by bilaterally exchanging information between the user and power producer. In addition, it alleviates environmental problems by using renewable energy resources. However, smart grids have many cyber security risks because of the bilateral service, the increase of small and medium-sized energy resources, and the installation of multi-sensors or control devices. These cyber risks can cause critical problems within a national grid through even small errors. Therefore, in order to reduce these risks, it is necessary to establish a cyber security strategy and apply it from the developmental stage to the implementation stage. This thesis analyzes and recommends security strategy in order to resolve the security risks. By applying cyber security strategy to a smart grid, it will provide a stepping-stone to creating a safe and dependable smart grid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.16-22
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• 2020

The characteristics of the LCL filter for grid-connected inverters have been discussed in academia and industry. An online simulation tool was applied to compare and analyze the difference between the LCL filter and L filter. LCL filters were modeled and simulated using a range of professional simulation simulators, and the LCL filters were found to have good filtering effects for high-frequency harmonics. First, this paper summarizes the transfer functions of the LCL filter and provides the Bode plot diagram. The accuracy and validity of the filter attenuation characteristics were confirmed by a fast Fourier transform based on off-line simulation tools, such as PSIM and MATLAB, depending on the given parameters of the LCL filter. Finally, the Typhoon HIL402 real-time simulation was performed for hardware in the loop simulation to verify the actual filtering characteristics of the LCL filter.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.749-755
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• 2022

Electricity is essential energy in modern society, such as being used in various industries. However, the rate of fires occurring on electric wiring to deal with it is very high. In this work, we implemented a system to predict the temperature change of an electric circuit through analysis using various regression models. To do so, we collected the temperature data of 27 types of magnetic switches which control electric circuits as well as trained the regression models by using the collected temperature data. In our experiments, we confirmed that the regression models can be trained at a sufficiently usable level since the difference between the actual temperature and predicted temperature is about 4℃. The results of our work will be useful to predict the temperature of electric circuits and preventing fires on them.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.81-87
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• 2006

The rubblization technique is breaking the aged concrete pavement slab into rubblized concrete aggregate, and use it as an base material at its original position, then builds overlay above the rubblized base. This method has been successively used in USA due to the advantage of good constructibility, cost-effectiveness as well as the capability of preventing of reflection cracks. However, constructibility and economic performance of rubblization on typical Korean concrete pavements needed to be investigate since to typical Korean concrete pavements have thick slab, as well include lean concrete subbase course. Multi-head type breaker suitable for Korean condition was designed and developed. This multi-head type breaker was designed to rubblize old concrete to the suggested optimum rubblized-depth and rubblized-concrete-aggregate size to prevent reflection crack and maintain high bearing capacity. This machine was used for the test of rubblization of old concrete pavement on a non-use old concrete and a in-serviced road. In these two tests, engineering properties of rubblized base and constructability and cost were investigated. In both tests, the old concrete rubblized to targeted size and depth, and high-level bearing capacity was achieved. Also, superior constructability and lower cost compared with traditional reconstruction was examined.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.610-620
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• 2023

The interest in the aircraft interior market is gradually growing due to technological development based on the 4th industrial revolution and competition for airlines to attract customers, and as part of that, Cabin Display System (CDS) for FAA Part.25 civil aircraft is being developed in Korea. The CDS is a system that provides various multimedia services to passengers by utilizing Flexible and Transparent Organic Light Emitting Diodes (OLED) with Integrated Display Processing Module (IDPM). This paper presents a new method for efficient Data Load Process of large-sized files and deals with their implementation and performance. The results of this study are expected to be applied to Data Load Process development of avionics that require reliable large-capacity file transmission along with reducing the costs of development compared to existing ARINC-615A.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.329-352
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• 2005

Long term observations of full-disk Lyman-o irradiance have been made by the instruments on various satellites. In addition, several sounding rockets dating back to the 1950s and up through the present have measured the $Lyman-{\alpha}$ irradiance. Previous full disk $Lyman-{\alpha}$ images of the sun have been very interesting and useful scientifically, but have been only five-minute 'snapshots' obtained on sounding rocket flights. All of these observations to date have been snapshots, with no time resolution to observe changes in the chromospheric structure as a result of the evolving magnetic field, and its effect on the Lyman-o intensity. The $Lyman-{\alpha}$ Imaging Solar Telescope(LIST) can provide a unique opportunity for the study of the sun in the $Lyman-{\alpha}$ region with the high time and spatial resolution for the first time. Up to the 2nd year development, the preliminary design of the optics, mechanical structure and electronics system has been completed. Also the mechanical structure analysis, thermal analysis were performed and the material for the structure was chosen as a result of these analyses. And the test plan and the verification matrix were decided. The operation systems, technical and scientific operation, were studied and finally decided. Those are the technical operation, mechanical working modes for the observation and safety, the scientific operation and the process of the acquired data. The basic techniques acquired through the development of satellite based solar telescope are essential for the construction of space environment forecast system in the future. The techniques which we developed through this study, like mechanical, optical and data processing techniques, could be applied extensively not only to the process of the future production of flight models of this kind, but also to the related industries. Also, we can utilize the scientific achievements which are obtained throughout the project And these can be utilized to build a high resolution photometric detectors for military and commercial purposes. It is also believed that we will be able to apply several acquired techniques for the development of the Korean satellite projects in the future.

• 전기의세계
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• v.24 no.4
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• pp.3-5
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• 1975

우리 인간은 그들이 개발한 과학과 기술에 의하여 자연 중에 존재하는 많은 자원을 그들의 생활에 도움이 되는 물체로 바꾸어 왔고 각종 에너지를 그들이 필요로 하는 형태로 바꾸었으며 또 그들이 사는 환경을 더욱 안락하도록 개조하여 왔다. 인간에 계속해서 현재와 같이 생활상태를 향상시키며 번영을 시도한다면 과학기술개발은 영원히 계속될 것이다. 이 과학기술개발에 관한 노력은 과거에는 가치관의 차이로 국가간의 노력의 차이가 있었으나 현재는 선후진국을 막론하고 과학기술에 의한 공업진흥이 국가사회의 경제개발의 원동력이며 그 생활향상의 열쇠가 된다는 것을 다 깨닫고 있다. 이와 같은 과학기술과 인간생활과의 숙명적인 관계중에서도 전기학술과 인간관계는 타과학과의 관계보다 훨씬 깊은 바가 있다. 우리는 호수에 물의 위치 에너지, 석탄이 가지고 있는 열에너지, 바람이 가지고 있는 운동에너지 등을 비롯하여 최근에 발견된 원자에너지까지도 이를 전기에너지로 변환시켜서 이용하고 있다. 장래 어떠한 에너지가 새로 개발되더라도 전기에너지로 변환되어 현재와 같이 우리 생활에 기여할 것은 틀림없다. 이는 전기에너지의 사용편리성으로 볼 때 이의를 제기할 사람은 없을 것이다. 따라서 각종에너지를 전기에너지로 바꾸는 발전기술과 이 장치의 제조공업, 이를 수요지까지 수송하는 송변전기술과 이 장치의 제조공업, 공장에서 사용되는 전기기기들의 운전사용기술과 가정에서 소요되는 전기기기의 제조공업 이상 전기공업의 여러 방치에 소요되는 원자재의 제조공업 등 소위 전기기술은 인간생활과 절대 불가분의 기술이며 앞으로도 인류의 존재와 더불어 영원한 발전을 계속할 것이다. 전기기술발전없이 인간사회와 국가의 산업발전을 기대한다는 것은 어리석은 일이라 아니할 수 없다. 가까운 장래 우리나라 계통이 당면하여야 할 계통제어에 관한 몇가지 문제를 고찰하고저 한다. 단 개개의 문제에 관한 구체적인 해석 또는 검토에 관하여는 다음 기회에 미루기로하고, 우선 여기서는 당면문제로서 대처하지 않으면 안될 자동주파수제어문제및 계통의 경제운용문제만에 한정하여, 이것을 우리나라의 현상과 관련시켜 개설하고, 이들의 자동화에 관한 기본적인 문제를 간단히 적어 보겠다. 가능하다. 제작완료된 ASIC은 기능시험을 완료했으며 실제 line-of-sight(LOS) 시스템 구현에 적용중이다. 시대를 살아 갈 회원들이다. '컨텐츠의 시대'가 개막되는 것이며, 신세기통신과 SK텔레콤은 선의의 경쟁 과 협력을 통해 이동인터넷 서비스의 컨텐츠를 개발해 나가게 될 것이다. 3배가 높았다. 효소 활성에 필수적인 물의 양에 따른 DIAION WA30의 라세미화 효율에 관하여 실험한 결과, 물의 양이 증가할수록 그 효율은 감소하였다. DIAION WA30을 라세미화 촉매로 사용하여 아이소옥탄 내에서 라세믹 나프록센 2,2,2-트리플로로에틸 씨오에스터의 효소적 DKR 반응을 수행해 보았다. 그 결과 DIAION WA30을 사용하지 않은 경우에 비해 반응 전환율과 생성물의 광학 순도는 급격히 향상되었다. 전통적 광학분할 반응의 최대 50%라는 전환율의 제한이 본 연구에서 찾은 DIAION WA30을 첨가함으로써 성공적으로 극복되었다. 또한 고체 염기촉매인 DIAION WA30의 사용은 라세미화 촉매의 회수 및 재사용이 가능하게 해준다.해준다.다. TN5 세포주를 0.2 L 규모 (1 L spinner flask)oJl에서 세포간의 응집현상 없이 부유배양에 적응,배양시킨 후 세포성장 시기에 따른 발현을 조사한 결과 1 MOI의