• Journal of Power Electronics
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• v.15 no.1
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• pp.268-277
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• 2015

In this paper, a dual-converter three-phase pulse width modulation (PWM) rectifier based on unbalanced one-cycle control (OCC) strategy is proposed. The proposed rectifier is used to eliminate the second harmonic waves of DC voltage and distortion of line currents under unbalanced input grid voltage conditions. The dual-converter PWM rectifier employs two converters, which are called positive-sequence converter and negative-sequence converter. The unbalanced OCC system compensates feedback currents of positive-sequence converter via grid negative-sequence voltages, as well as compensates feedback currents of negative-sequence converter via grid positive-sequence voltages. The AC currents of positive- and negative-sequence converter are controlled to be symmetrical. Thus, the workload of every switching device of converter is balanced. Only one conventional PI controller is adopted to achieve invariant power control. Then, the parameter tuning is simplified, and the extraction for positive- and negative-sequence currents is not needed anymore. The effectiveness and the viability of the control strategy are demonstrated through detailed experimental verification.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2107-2114
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• 2009

It is impossible to take the instant action in the distribution system When fault occures in a substation because operation of the substation and the distribution system are separated. However the power system automation has been studying about unity operation and co-operation between SCADA and DAS(Distribution Automation System). In this paper proposes a new algorithm of efficiency restoration using a outage load switching to a healthy MTR a fault occurrence at a MTR in united system between DAS and SCADA. In addtion, proposed algorithm includes a outage restoration method which keeps MTR optimal capacity with reorganization of distribution network in case it can not restore outage state loads caused by shortage of healthy MTR remain capacity. In case that proposed sequence still can not complete restoration, this paper suggests a efficiency outage restoration with objective function included priority in outage loads. In the case studies, the proposed algorithm have been verified in 2 MTR and 3 MTR substation

• Transactions of Materials Processing
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• v.23 no.2
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• pp.75-81
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• 2014

Progressive dies are used for metal stamping during which multiple operations are performed in a sequence. Material is fed automatically from a coil into the press and advances from one die station to the next with each press stroke. Transfer dies are used in high-volume manufacturing for round, deep-drawn, and medium-to-large parts. Several different operations may be incorporated within a transfer die such as blanking, bending, piercing, trimming, and deep drawing. The main challenge in the current study is how to deform a seat cushion panel meeting the design specifications without any defects. A complex automation die manufacturing technology for the automotive seat cushion panel, mixing both semi-progressive die and transfer die for continuous production, was developed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.10a
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• pp.48-56
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• 1995

A manufacturing process for the axle-housing is analyzed by the rigid-plastic finite element method. The process contains five stages for the final product. During the simulation, remeshings are done four times due to severe mesh distributions. FE Analysis is performed mainly for strain distributions and load-stroke relationships. Those results are to be an useful design criteria for designing a new process sequence in future.

• International Journal of Control, Automation, and Systems
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• v.1 no.4
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• pp.444-452
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• 2003

An integration system with multi-measurement sets can be realized via combined application of a centralized and federated Kalman filter. It is difficult for the centralized Kalman filter to remove a failed sensor in comparison with the federated Kalman filter. All varieties of Kalman filters monitor innovation sequence (residual) for detection and isolation of a failed sensor. The innovation sequence, which is selected as an indicator of real time estimation error plays an important role in adaptive mechanism design. In this study, the centralized Kalman filter with adaptive measurement fusion is introduced by means of innovation sequence. The objectives of adaptive measurement fusion are automatic isolation and recovery of some sensor failures as well as inherent monitoring capability. The proposed adaptive filter is applied to the GPS/SDINS integration system with an additional sensor. Simulation studies attest that the proposed adaptive scheme is effective for isolation and recovery of immediate sensor failures.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.31-32
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• 2007

In this paper, a fault section detection method is proposed for ungrounded system in the case of a single line-to-ground fault. A conventional method is used for faulted feeder selection according to the angular relationship between zero-sequence currents of the feeders and zero-sequence voltage of the system. Fault section detection is based on the comparison of phase angle of zero-sequence current. Proposed method has been testified in a demo system by Matlab/Simulink simulations. Based on Distribution Automation System(DAS), Feeder Remote Terminal Unit(FRTU) is used to collect those necessary data, at present a demo system is under developing using Manufacturing Message Specification (MMS) in IEC61850 standard.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.129-134
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• 2013

Previous research is focus on testcase generation automation using message sequence diagram based on metamodel. but that research is not enough for testcase genaeration automation using state diagram based metamodel. so in this paper is adopt Model Driven Architecture (MDA) mechanism for using metamodel and model transformation. and we suggest testcase automation mechanism using state diagram in UML. we will decrease cost of embedded software design and testcase genaration and increase quality of embedded software using metamodel mechanism.

• Proceedings of the KIEE Conference
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• summer
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• pp.339-341
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• 2004

전력 계통은 거대한 네트워크화되고 있으며, 전력계통을 신뢰성 있게 운용하는 것이 어려워지고 있다. 이에 따라 전력계통에 대한 숙련된 운전기술이 필요하게 되고, 실제 전력계통 모의를 통한 미경험 고장의 처리기술을 습득해야할 필요성이 생기게 되었다. 그러한 취지에서 각종 유틸리티는 운용자 지원 소프트웨어나 고장의 발생과 복구를 훈련할 수 있는 시뮬레이터를 대부분 구비하고 있다. 이러한 프로그램의 핵심적인 기능은 고장의 시나리오를 실제 계통에서 발생할 수 있는 고장으로 상정하고, 전문가 그룹에 의해 도출된 복구절차에 의해 복구 과정을 훈련하는 것이다. 전력계통이 복잡화되고 거대화됨에 따라 복구절차 또한 복잡화되고 있으므로 기존의 Case-by-case에 의해 복구절차를 생성하는데는 한계가 있다. 그러므로 본 연구에서는 Lex라는 구문분석기와 Yacc라는 파서를 이용하여 복구절차 생성시 복구 절차를 적절한 그룹을 만들고, 과 그룹을 통해서 조합 가능한 모든 복구 조작 순서를 생성하기 위한 그룹핑 알고리즘을 구현하고자한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.10
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• pp.1418-1425
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• 2015

In this paper, an filtering method of FI(Fault Indication) information generated by FRTU(Feeder Remote Terminal Unit)s is proposed for the present DAS(Distribution Automation System). In order to find fault area, correct FI information should be generated. But when a single line-to-ground fault occurs, FI information is generated in downside of the fault in some circumstance because existing FI algorithm considers only magnitude. These wrong FI information can be removed by changing existing algorithm. An improved algorithm considers both the direction of zero-sequence current and the phase of three-phase current&voltage. But many FRTUs are distributed in DAS and Changing the algorithm all of FRTU will spend a lot of time and cost. On the other hand, an filtering algorithm proposed in this paper can substitute for it. The filtering algorithm also considers both the direction of zero-sequence current and the phase of three-phase current&voltage. In case study, the proposed method has been shown the reasonability in filtering the fault indication information.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.56-61
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• 2019

In this country, mackerel landing, sorting, and packing are mostly performed manually, which is time consuming and labor intensive. An unloading automation system saves time and labor by automating the landing, sorting, and packing processes. Casers are devices for manufacturing packing boxes for fish used by unloading automation systems. The caser design in this study is for mackerel packing boxes. This caser makes a packing box based on a press using the caser's slide crank. When the caser makes a packing box, the manufacturing sequence is determined by the caser's production guide and assisting rod. The caser design in this study is simulated using a multi-body dynamics program. The simulation is used to analyze the caser and to visualize the box-making sequence.