• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.1
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• pp.69-76
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• 1999

This paper proposed a design of intelligent supervisory control systems for maintenance of highway traffic information equiprrent and processing algorithm of equiprrent fault data. The fault data of highway traffic equipment are transmitted from rerrnte supervisory controller to central supervisory system by real time, the transmitted fault data are anaIyzed the characteristic using evaluation algorithm of fault data in central supervisory system. The evaluation algorithm includes a neural network and fault knowlOOge-base for processing the multi-generated fault data. For validating the evaluation algorithm of intelligent supervisory control systems, the rrethod of analysis used to the five pattern of binary signal by transmitted real time and the opTclting user-interface constructed in central supervisory system.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.953-960
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• 2002

Rel-time application programs have constraints which need to be met between media-data. It is client-leading synchronization that is absorbing variable transmission delay time and that is synchronizing by feedback control and palyout control. It is the important factor for playback rate and QoS if the buffer level is normal or not. This paper, The method of maintenance buffer normal state transmits in multimedia server by appling feedback of filtering function. And synchronization method is processing adaptive playout time for smooth presentation without cut-off while media frame is skip. When audio frame which is master media is in upper threshold buffer level we decrease play out time gradually, low threshold buffer level increase it slowly.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.448-457
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• 2013

This paper proposes a control method under stand-alone operating mode for distributed-module type photovoltaic power conditioners. In conventional schemes, there are some problems of a controller saturation in the DC-link (or load) voltage controller when overly-heavy load, light load, and the generated PV power reduction occurs, as well as when a transition occurs from an overly-loaded to normal conditions. To overcome these problems, the proposed controller method switches the main control target from DC-link voltage to the maximum power point, which is closer to the stable operating point when it returns to normal operating conditions. For the analysis, a state-plane trajectory was given and the circuit analysis by PSIM simulation was done. For the verification, a prototype hardware with 110[W] and 50[W] dual photovoltaic modules has been implemented. From the results, it can be seen that PV power tracking is successfully done with the proposed method even under a stand-alone operation mode.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1193-1203
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• 2016

This paper proposes a droop control scheme to compensate the unbalanced line-to-line voltage of unbalanced 3-phase load which is coupled with two inverter-based distributed generations through unequal impedance lines. Unbalanced line-to-line load voltages occur due to using single-phase loads, which brings about bad effects on the coupled inverters and the distributed generations. In order to compensate the unbalanced line-to-line voltages, a positive sequence voltage control was used for sharing the active and reactive power and a negative sequence control was used for reducing the negative sequence voltage. The feasibility of the proposed scheme was first verified by computer simulations, and then experiments with a hardware set-up built in the lab. The experimental results were compared with the simulation results to confirm the feasibility of the proposed scheme.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.154-154
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• 2009

본 연구는 고전압 전력기기인 몰드형변압기와 계기용 변성기인 CT, PT 절연특성에 유용한 Epoxy/Nano-Micro Mixture Composites(이하,ENMMC)를 개발하기위해 무엇보다 중요한 것은 Nano입자인 $SiO_2$_10nm입자의 표면을 제어하여 즉, 표면의 소수성을 크게 하여 나노입자의 균질한 분산을 얻은것이 무엇보다 중요하다. 개발된 Epoxy/$SiO_2$_10nm Nanocomposites와 Microcomposites을 기계적 전단응력을 이용하여 균질 혼합을 실시하였다. 이런 조건을 이용한 전기적특성을 측정하기위해 구대구 전극이 완전함침된 평등전계하에서 절연파괴전압을 측정하기 시편을 제조하였다. 마이크로입자의 충진함량을 일정하게 유지하여 나노입자 충진함량비율을 4가지로 변화시켜 절연파괴특성을 연구하였다. 충진함량이 나노입자의 경우 1wt%이하의 값이 상대적으로 우수한 절연파괴특성으로 와이블 플롯을 통하여 알수있었다. 상대적으로 멀티나노콤포지트의 형상파라미터가 큰 결과값을 얻을수 있었다. 그리고 스케일파리미터는 누적확률 밀도함수로서 63.2%에서 대단히 큰 초절연성의 절연소재를 개발할수 있었다.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.5
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• pp.424-431
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• 2007

This thesis proposed H-Bridge Multi-Level Inverter for Fluidized Bed Combustion Boiler Secondary Air Fan in 200MW thermal power plant. The adjustable speed drive systems improve the efficiency in lightly load condition and extend the life span of motor by limiting the over current at starting. H-Bridge Multi-level Inverter is composed of the several series low voltage power cell inverters, which have the independent isolated do link, in each phase. KEPRI(Korea Electric Power Research Institute) has successfully completed to develop, install, and commission H-Bridge Multi-level Inverter(6.6kV, 1MVA). This thesis gives a full detail about H-Bridge Multi-level Inverter, proposed boiler DCS(Distributed Control System) logic, and commissioning test result.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.4
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• pp.1-9
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• 2015

Since logical ground and method to deduct location to install Integrated Standard Controller under development to combine physically and functionally multiple enclosures of controllers for various ITS equipments on streets into one enclosure, there are much difficulty to apply it to site. Particularly we need to establish standardized methodology to deduct optimal location to integrate individual controllers installed dispersedly on streets such as node part and line part. Accordingly this study has the purpose of suggesting more reasonable and efficient methodology to determine location for Integrated Standard Controller to be developed newly. For this, new solution has been searched by using centroid which is utilized to decide facility location in urban planning. As the result of analysis, central point among centroid, in which equal connection to each equipment is possible is proved to be the most reasonable and correct coordinate and zone is proposed as installation location through designating coordinate system. The methodology suggested by this study seems to have high degree of utilization in site according to expansion of integrated standard controller market.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.1
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• pp.73-77
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• 2012

In this article, we designed a wide bandpass filter in order to apply microwave reflectometry for KSTAR. The proposed wide bandpass filter consists of a metamaterial structure which is to get a wide band, a lower insertion loss, and a high skirt. This is applied to VCO's output to enhance the linearity. A pass band is 18-28 GHz and the out of pass band is stopped over 20 dB. To confirm of the metamaterial, we suggest a dispersion diagram. The proposed filter in lower band and upper band of pass band is respectively a left handed and right handed characteristics. A group delay is below 0.5 ns.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.181-186
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• 2017

The system optimization is a technique that changes the structure of the program in order to extract the duplicated modules without changing the source code, reuse of the extracted module. Structure-oriented development and object-oriented development are efficient at crosscutting concern modular, however can't be modular of crosscutting concept. To apply the crosscutting concept in an existing system, there is a need to a extracting technique for distributed system optimization module within the system. This paper proposes a method for extracting the redundant modules in the completed system. The proposed method extracts elements that overlap over a source code analysis to analyze the data dependency and control dependency. The extracted redundant element is used to program dependency analysis for the system optimization. Duplicated dependency analysis result is converted into a control flow graph, it is possible to produce a minimum crosscutting module. The element extracted by dependency analysis proposes a system optimization method which minimizes the duplicated code within system by setting the crosscutting concern module.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.569-576
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• 2011

This paper proposes a new dead time compensation method for a PWM inverter. Recently, PWM inverters are extensively used for industry applications, such as ac motor drives, distributed grid-connected systems and a static synchronous compensator (STATCOM). Nonlinear characteristics of the switch and the inverter dead time cause a current distortion and deterioration of power quality. The dominant harmonics in the output current are the $5^{th}$ and $7^{th}$ harmonics in the stationary frame, and the $6^{th}$ harmonics in the synchronous rotating frame. In this paper, a resonant controller which compensates the $6^{th}$ harmonics in the synchronous rotating frame is proposed. This method does not require any off-line experimental measurements, additional hardware and complicated mathematical computations. Furthermore, the proposed method is easy to implement and does not cause any stability problem.