• Journal of international Conference on Electrical Machines and Systems
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• 제2권3호
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• pp.269-274
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• 2013

Fault-tolerant capability, wide speed range and overload capability are required in electric motors used in electric vehicles. In this paper, based on the analysis of the all poles wound and alternate poles wound flux-switching permanent-magnet machines, an optimization method is studied to reduce torque ripple. The method takes account of both flux-leakage and cogging torque. The simulation result shows that the method can reduce the torque ripple effectively. This study lays the foundation for the further application of FSPM in electric vehicles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1023-1025
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• 1999

This paper provides the steady-state UPFC model referred as UPFC injection model for power flow control. The application of UPFC for the line overload alleviation is demonstrated through a numerical example. It is shown that UPFC has the capability of regulating the power flow, therefore alleviating the line overload.

• 디지털산업정보학회논문지
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• 제8권3호
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• pp.87-95
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• 2012

Up to now, industrial cranes play important roles as the effective machines to carry heavy loads in the manufacturing premise, in the construction field and so on. And, a crane is widely used not only to daily work but also to carry heavy materials efficiently in a construction site for prevention of accident. However, the crane operation is highly complicated even for experts. In this paper, we developed the content of the crane mounted on the controller. This content overload conditions in the operating environment for the crane operator to warn, and the operation of equipment has the capability to limit automatically. The content for crane controller is to alert the operator overload and to limit the operation of equipment for stabilizing capabilities. The content of the flexible algorithm is based on stabilizing controllers, PLC (Programmable Logic Controller) to connect for using the equipment and electrical control systems to ensure the safety of workers and to improve the ability to work possible.

• ETRI Journal
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• 제20권2호
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• pp.115-132
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• 1998

This paper proposes an extended service filtering technique to prevent overload in service control point (SCP) due to televoting (VOT) or mass calling (MAS) services with the heavy traffic characteristics. Also, this paper compares this extended technique with the existing overload control techniques, and calculates steady state call blocking probabilities in intelligent network (IN) under overload conditions. The proposed technique considers SCP overload and IN Capability Set (CS)-1 services (such as VOT or MAS service) that have to use the specialized resources of intelligent peripheral (IP). This technique uses first an activating step in which SCP requests service filtering to service switching point (SSP). Then, in the filtering step, SSP sends filtering results to SCP periodically or each N-calls. Also, when filtering time-out expires, SSP stops service filtering, and sends service filtering response to SCP in the deactivating step. This paper applies this technique to VOT/MAS service, and calculates SCP and SSP-IP (circuit) call blocking probabilities by using an analytical VOT/MAS service model. With the modeling and analyzing of this new technique, it shows that this technique reduces the traffic flow into SCP from SSP and IP prominently.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1046-1052
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• 2017

The load on the power grid of South Korea is expected to grow continuously until the late 2020s, and it is necessary to increase the transfer capacity from the Eastern grid to the Seoul-Gyeonggi region by reinforcing the transmission network for the electric power system to remain stable. To this end, the grid reinforcement by two bipole LCC HVDC transmission systems have been considered on account of the public acceptability and high growth of the fault current level, even though an additional 765kV system construction is more economical. Since the probability of the existing 765kV double circuit transmission line trip is extremely low, a dynamic simulation study was carried out to estimate the efficient HVDC capacity able to stabilize the transient stability by utilizing the HVDC overload capability. This paper suggests the application plan to reduce the HVDC construction capacity with ensuring the transient stability during the 765kV line trip.

• 대한전기학회논문지
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• 제36권4호
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• pp.231-239
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• 1987

Distribution system is one of large and complicated sytem, consisted of a great number of components. Therefore efficient operation based on precise analysis and computation methods is indispensable accommodating growing loads. This paper describes an optimal operation problem to relieve overload flow in radial distribution systems by using modified block model. The problem is formulated as a network problem of synthesizing the optimal spanning tree in a graph, branch and bound method is used for the optimization. Especially modified block model proposed in this paper is validated more practical than conventional model. These methods can be applied to two types of distribution system problems such as, 1) planning problem to check the capability of relieving overload at normal rating, 2) emergency operation problem to determine switching scheme for minimizing customer loads affected by a fault. Examples of application to these problems are discussed.

• 정보처리학회논문지D
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• 제15D권5호
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• pp.699-704
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• 2008

인터넷의 대중화로 웹에 대한 의존도가 높아지고 사용자가 증가로 인하여 웹 서비스 성능과 커뮤니케이션의 보안 문제가 중요한 이슈가 되고 있다. 기존의 웹 서비스 기술은 동시 클라이언트 개수의 제한과 서버 처리량의 감소 그리고 평균 응답 시간을 증가시켜 웹 어플리케이션 서버의 성능을 감소시킨다. 그리고 커뮤니케이션 보안을 위한 메시지 암호화 작업과 초기 handshake 비용은 연결에 필요한 계산 시간을 증가시켜 전송 속도와 서버 성능을 감소시킨다. 따라서 본 논문에서는 보안 요구사항을 만족하고 동시에 웹 서비스를 위하여 서버의 과부하를 개선하고 웹 서버 아키텍처의 신뢰성과 안전성을 위하여 타원곡선 암호화(ECC) 알고리즘을 이용하여 암호화 처리를 수행하고, 향상된 성능과 지연처리에 필요한 기술을 제공하는 개선된 모바일 웹 서버를 제안한다.

• The Journal of the Acoustical Society of Korea
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• 제17권4E호
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• pp.28-34
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• 1998

In most switching system, the processing unit is designed to work efficiently even at relatively high loads, but when the offered traffic exceeds a particular level, the rate of completed calls can fall drastically. A single call handled by the switching system consists of a sequence of events or messages that has to be processed by the control unit. The control unit is not only incapable of handling all of the offered calls, but also its call handling capability can drop as the offered load increases. The real time available for call processing is a critical resource that requires careful management. Therefore, the overloading of this resource must be detected by a subscriber in the from of a dial tone delay or an uncompleted call which is either blocked or mishandled. The subscriber may respond by either dialing prematurely or by re-attempting a call. This action can further escalate the processors load, which is spent for uncompleted calls. Unless a proper control is used, the switching system can finally break down. In this paper, we paper, we propose a fuzzy overload detection and control method for switching systems, which can by generating fuzzy rules via fuzzy aggregation networks. Simulation results involving a switching system is given.

• 융합보안논문지
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• 제16권7호
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• pp.41-49
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• 2016

오늘날 정보통신기술이 발달함에 따라 전산화된 의료정보의 유출 및 보호 문제가 사회적 이슈가 되었다. 더불어 정부에서도 의료기관의 정보보호를 위해 제도적 개선을 진행하고 있다. 그러나 의료기관의 정보보호 역량을 제고하기 위한 노력들은 자칫 의료기관 종사자들에게 스트레스를 증가시키고, 나아가 의료기관의 본질인 의료서비스의 질 하락을 야기할 수 있다. 따라서 의료기관이 관리하는 정보의 보호를 강화함에 있어서 의료기관 종사자들의 보안에 따른 스트레스 정도 및 그 선행요인들에 대해 연구할 필요성이 있다. 기존 연구를 분석하여 보안스트레스와 보안스트레스에 영향을 미치는 요인을 선정하였다. 이를 통해 업무 과중, 프라이버시 침해 그리고 업무 불확실성이라는 변수를 도출하였다. 본 연구는 국내 병원 종사자들 123명의 데이터를 수집, SPSS 21.0을 사용하여 검증하였다. 본 연구의 결과로 업무 과중, 프라이버시 침해, 그리고 업무 불확실성의 일부는 보안 스트레스에 정(+)의 영향을 미치는 요인으로 나타났다.

• 디지털산업정보학회논문지
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• 제12권4호
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• pp.71-79
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• 2016

This study proposes a performance model of a shared bus multi-processor system and analyzes the effect of input/output types on system performance and overload of shared resources. This system performance model reflects the memory reference time in relation to the effect of input/output types on shared resources and the input/output processing time in relation to the input/output processor, disk buffer, and device standby places. In addition, it demonstrates the contribution of input/output types to system performance for comprehensive analysis of system performance. As the concept of workload in the probability theory and the presented model are utilized, the result of operating and analyzing the model in various conditions of processor capability, cache miss ratio, page fault ratio, disk buffer hit ratio (input/output processor and controller), memory access time, and input/output block size. A simulation is conducted to verify the analysis result.