• Convergence Security Journal
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• v.8 no.4
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• pp.167-179
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• 2008

As ubiquitous technology develops, there are many studies to provide various contents proper to users through a mobile device. However, there is a limit of information provision due to a small user interface of a mobile device. This study proposes a system that can solve a problem and provide an intelligent agent model appropriate to a mobile environment and job information positively that an individual user is interested. It is composed of a personalization engine to monitor users' behavior patterns and a learning algorithm to provide information to a mobile device. Analysis shows that preferred job items are different by sex, age and education, while a region affects job searching significantly.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.359-365
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• 2002

Three-phase four-wire electrical distribution systems have been widely employed in manufacturing plants, commercial and residential buildings. Due to the nonlinear loads, the neutral conductor carries excessive harmonic currents resulting in wiring failure of the neutral conductor, overloading of the distribution transformer and a voltage drop between the neutral and the ground. This paper proposes a reduced rating active power filter to suppress neutral current harmonics in three-phase four-wire electrical distribution systems. The proposed system is simple in control and the VA rating of the inverter could be significantly reduced since only the fundamental current due to unbalanced loading flows through the inverter switch. The experimental results on a prototype validate the proposed control approach.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.504-505
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• 2008

정보통신기기 및 컴퓨터시스템 등은 순간정전, 전압변동, 노이즈, 정전기, 고조파전류 등의 영향을 쉽게 받는다. 따라서 이러한 점을 충분히 고려하여 신뢰성과 안전성을 확보하도록 구성되어야 한다. 전력 품질이 강조되는 이유는 컴퓨터는 물론 각종 가전제품 등이 복잡하고 정밀한 전자회로로 구성되어 있어 조그만 전압변동이나 정전사고에도 전자회로가 오작동을 일으키거나 고장날수 있기 때문이다. 이에 본 논문에서는 분산형 태양광 발전이 계통에 연계되었을 경우 발생할 수 있는 전력품질에 영향을 끼치는 요인 중 하나인 고조파를 저감시키기 위한 능동형 필터 모델을 제안한다. 본 논문에서의 필터 모델은 PSIM을 이용하였으며, 능동형 필터 시스템의 장착 전 후의 고조파 및 잡음성분을 FFT를 이용하여 분석하여 시스템의 적용 가능성과 효용성을 본 논문에서 증명하였다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.11
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• pp.563-571
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• 2003

In this paper, the control algorithm and control method for a combined system of shunt passive filter and series active filter in 3-phase 4-wire system are discussed. Moreover, the three-phase four-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and its 3th harmonics are termed as triple and zero sequence components that do not cancel each other in the system neutral. Consequently, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control algorithm for a series hybrid active system, whereas the control approach it adopts may directly influence its compensation characteristics. Hence, the advantage of this control algorithm is direct extraction of compensation voltage reference and the required rating of the series active filter is much smaller than that of a conventional shunt active filter. Some experiments were executed and experimental results from a prototype active power filter confirm the suitability of the proposed approach.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.83-89
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• 2009

The environment of electrical power industry is now faced on problems such as electric rates, an increasing sensitivity in society with environmental issues and energy factors. Up to now, reliability is greatly influenced by maintenance and environmental factors that are unique to the electric utilities. The reliability is a characteristic assigned to the electric power systems's function which is related to the concept of installment of equipment. Therefore this reports's key finding is that it is important that the utilities track their individual components' value over investment expense of their installed components. This can be accomplished to consider the cases of foreign electric power companies and take into account the various possible installment ways of equipment in Korea. These results are expected to be used as a reference material for design underground distribution facilities and future applications.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.41-46
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• 2013

IIn this paper, active trasfemoral prosthesis leg is designed for the handicapped who lost their legs upon knee. It is important to design proper knee joint to mimic walking motion of hyman. 1 degree-of-freedom active trasfemoral prosthesis leg is designed with knee joint. Operating angle and torque have been calculated using kinematics of three linkages in prosthesis leg. Finite element analysis of major components is performed to evaluate the safety under operating condition and to reduce weights. Minimum volumes of components are obtained by optimization as satisfying safety requirements. The results show that about 35% of weight of components is reduced.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.2
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• pp.255-265
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• 1999

Recently the necessity of MMIC is increasing because clock frequency goes up by digital data transmission of Gbps class being demanded and the density of circuits gets high for the purpose of lightening and miniaturizing system, owing to the development of ultra high speed. When massing lines in a MMIC and super high speed integrated circuit cause the crosstalk and dispersion of signal, a digital signal is distorted and EMI is occurred. To solve this problems, It is necessary to analyze the equivalent parameters of transmission lines. This paper represent the results of the equivalent parameters of transmission lines for single and hi-level structure by using moment method.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.78-84
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• 2016

The FHX (Forced-draft sodium-to-air Heat Exchanger) employed in the ADHRS (active decay heat removal system) is a shell-and-tube type counter-current flow heat exchanger with M-shape finned-tube arrangement. Liquid sodium flows inside the heat transfer tubes and atmospheric air flows over the finned tubes. The unit is placed in the upper region of the reactor building and has function of dumping the system heat load into the final heat sink, i.e., the atmosphere. Heat is transmitted from the primary cold sodium pool into the ADHRS sodium loop via DHX (decay heat exchanger), and a direct heat exchange occurs between the tube-side sodium and the shell-side air through the FHX tube wall. This paper describes the DHRS and the structural design of the FHX.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.137-140
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• 2007

전력계통의 환경변화(분산전원 연계, 구역전기사업자 출연 등)에 능동적으로 대응할 소비자-공급자간 양방향 통신/서비스 인프라의 핵심으로 Consumer Energy Portal의 필요성이 점점 증대되고 있다. 이는 에너지 서비스 사업자와 수용가 설비 및 기기들 사이의 양방향 통신을 가능하게 하는 H/W 및 S/W의 결합 또는 수용가의 In-Building Network와 Wide-Access Network를 연결하는 물리적인 Link이자 논리적인 결합 등과 같은 의미를 지닌다. 즉, Consumer Energy Portal은 전력에너지 체인의 운영방식을 물리적인 것에서 웹 방식으로 전환한 것으로 전력사업자와 소비자 사이의 양방향 상호작용을 가능케 하고 최종 소비자의 모든 기기들을 서로 네트워킹하며 이를 통해 과거 물리적인 방식의 운영과는 차원이 다른 다양한 서비스와 운영이 가능하게 하는 Service Portal이다. 본 논문은 수용가의 실시간 원격검침 데이터를 지그비(ZigBee) 통신기술을 이용하여 수집하는 것과 물리적으로 연결된 설비들을 제어할 수 있는 양방향 Network Access 망을 구축하여 전력사업자의 통합자원관리, 수요관리, 부가서비스제공에 기여하고자 한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.345-348
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• 2012

본 논문은 만성질환 환자를 위한 인체 삽입형 시스템을 구현하기 위해서 의료용 통신 기술을 사용한 생체신호의 송수신 및 제어가 가능하며, 무선전력전송 기술을 통해 반영구적 사용을 가능하게 하는 IT융합형 인체 삽압형 시스템 플랫폼 원천기술을 개발하고 생리기능(혈당, 혈압, 심장박동 등) 감시가 가능한 이식형 융복합 시스템 기술에 관하여 분석하였다. 인체삽입형 생리기능 자동감시 시스템은 사후진단 및 치료에서 능동적인 조기진단과 예방으로 진화하고 있으며 신기술 및 융합 기술이 의료기기의 응용 범위를 더욱 확대하는 방향으로 가고 있다. 미국/유럽 등 선진국이 대부분의 시장을 차지하고 있으므로 국내개발 성공시 수입대체 효과뿐만 아니라 기술적 격차 극복을 통한 세계 시장 진출도 가능하다. 이 분야는 세계적 경쟁력을 가진 국내 IT 산업과의 강한 시너지를 통하여 복합 기술형 첨단 의료기기의 기술경쟁력을 제고하고, 진입장벽이 높은 미래 첨단산업 시장 진출에 의한 국가전략산업 육성에 기여할 수 있을 것으로 기대된다.