• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.241-245
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• 2006

In the examination of Steam Generator (SG) tube in Nuclear Power Plant (NPP) Eddy Current Testing (ECT) probes play an Important role in detecting the defects. Bobbin probe and Rotating Pancake Coil (RPC) probe is usually used for the inspection of SG tube. Bobbin probe is good at high speed inspection, but ability of detection of circumferential defect is very weak. On the contrary RPC probe, which moves for inspection in the direction of axial and circumferential simultaneously, has very slow inspection speed, but it was excellent detection capability fur small cracks, which is hardly detected by bobbin probe. Many examinations of SG tube examination of NPP are achieved during short period. Therefore, solution about this must develop probe of new form for examination performance and examination time shortening of other probe. In this paper, analyzed technological present condition of Bob-bin probe and RPC probe been using in Nondestructive Testing (NDT) for SG tube defect detection and Appeared about background theory and view of developed probe newly.

• Journal of Applied Reliability
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• v.17 no.3
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• pp.224-235
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• 2017

Purpose: Reliability is the most important factor to detect defects as wind turbines are deployed in large blades. The methods of detecting defects are various, such as non-destructive inspection and thermal imaging inspection. We propose the phased array ultrasonic testing method of non-destructive testing. Methods: We propose the active pressure mechanism for wind power blade. The phase array ultrasonic inspection method is used for fault detection inner blade surface. Controlled pressure of mechanism with respect to z-axis is important for guarantee the result of phase array ultrasonic inspection. The model based control and proposed mechanism are utilized for overall system stability and effectiveness of system. Result: The result of proposed pressure mechanism B is more stable than A. Convergence speed is also faster than A. Conclusion: We confirmed the performance of the proposed constant pressure mechanism through experiments. Non-destructive testing was applied to the specimen to confirm the reliability of detecting defects.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.16-24
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• 2021

Solar array simulator (SAS) is essential equipment in testing and evaluating the power processing performance of a power conditioning system. However, the nonlinearity in the current(I)-voltage(V) characteristic makes the control loop design of SAS a challenging task. Conventionally, only the inner loop is usually considered in the control design approach. However, this study proves that the reference generation loop also interacts with the inner loop and plays a key role in the overall performance of the SAS. In this paper, the performance of voltage-mode control and impedance control, which are two of the most popular architectures for the SAS system, are reviewed and compared by multi-loop analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1224-1230
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• 2007

In this paper, we study the classification of defects at steam generator tube in nuclear power plant using eddy current testing (ECT). We consider 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. In order to improve the classification performance, we propose new feature extraction technique. After extracting new features from the generated ECT signals, multi-layer perceptron is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves 100% classification success rate while the previous method yields 91% success rate.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.767-772
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• 2008

Korea Electric Power Research Institute in charge of the power IT project "Development of Prototype for Advanced Substation Automation System based on the Digital Control Technology", is performing the verification of performance of the substation automation system. In order to verify a system based BUS protection IED, the standardized document and procedures are required. But there is nothing to describe systematically how to verify IEC 61850 based IED in the system environment except an individual IED testing way and report. This paper presents the substation automation system based ways and procedures to verify the IED using UML(Unified Modelling Language).

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.348-350
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• 2003

In recent years, with the continuous development of modem power system, the need for high performance protection to meet the customers' requests for more stable and reliable power supply has become increasingly emphasized. So, there is urgent need for a proper testing platform about not only existing digital protection relay but also new digital protection relay on the transmission line. It is also dynamic-state test which can test the performance of digital relay. This paper suggests basic system model for testing transmission line protection using PSCAD/EMTDC, and presents the process of the component modeling in the basic system.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.567-569
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• 2000

대전력시험 설비 중 단락발전기는 시험에 필요한 에너지를 발생시키는 근원으로서 시험하고자 하는 피시품의 시험용량에 따라 설계되고 제작되어야 한다. 본 논문에서는 LG산전 대전력시험 설비 중 단락발전기에 대한 설계 개념, 전기적 및 기계적인 특성, 또한 일반 발전기와는 다르게 특별히 설계된 주요 특징 등에 대하여 기술하며, 피시품의 단락시험 중에 발생하는 시험 시퀀스 및 이에 대한 기술적인 내용을 기술한다. 또한, 단락발전기의 시운전 및 성능 확인 시험 결과에 대한 내용을 기술하고, 시험 중 발생할 수 있는 내용에 대하여 고찰하여 본다.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.559-565
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• 2009

Power dissipation during scan testing is becoming an important concern as design sizes and gate densities increase. The high switching activity of combinational circuits is an unnecessary operation in scan shift mode. In this paper, we present a novel architecture to reduce test power dissipation in combinational logic by blocking signal transitions at the logic inputs during scan shifting. We propose a unique architecture that uses dmuxed scan flip-flop (DSF) and transmission gate as an alternative to muxed scan flip-flop. The proposed method does not have problems with auto test pattern generation (ATPG) techniques such as test application time and computational complexity. Moreover, our elegant method improves performance degradation and large overhead in terms of area with blocking logic techniques. Experimental results on ITC99 benchmarks show that the proposed architecture can achieve an average improvement of 30.31% in switching activity compared to conventional scan methods. Additionally, the results of simulation with DSF indicate that the powerdelay product (PDP) and area overhead are improved by 28.9% and 15.6%, respectively, compared to existing blocking logic method.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.3
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• pp.379-386
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• 2022

The goal of this research is to verify a performance test system for a low speed, high torque, and harsh reducer at low cost. The reducer rotates a cooling fan with a diameter of 10 meters, in a high temperature (50℃) cooling tower in a geothermal power plant. It requires about 500 kgf·m torque and 47.75 kW power to rotate the fan at a maximum power condition. An expensive dynamometer is commonly used for performance test of a motor or a reducer. In this paper, a low cost system is developed using a hydraulic pump as a load unit to generate torque instead of a dynamometer. We accurately calculated the required power, the flow meter, and the pressure of the pump, and selected to design and optimize the system at minimal cost. The system also applied another reverse reducer and a gearbox to increase the rotational speed and to reduce the torque from the low speed and high torque target reducer. This allows low-cost systems to be built using inexpensive components. The developed system was able to successfully measure the high torque and the low rotational speed of the target reducer at high temperature.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.640-642
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• 2008

This paper presents the design, development and performance of a 250kW power conditioning system(PCS) for large scale photovoltaic power plant. The PV inverter consists of a three phase IGBT stack, L-C filter, transformer and HMI unit for monitoring. To verify the performance of the PV inverter a testing facility was designed and constructed to simulate the characteristics of the solar cell and grid.