• 전기학회논문지
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• 제60권2호
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• pp.279-284
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• 2011

Harmonic distortions in current waveform may cause significant problems in electric power system facility and operation. This paper presents an adaptive parameter estimation method to detect harmonic current components caused by nonlinear loads. In addition, a coordination strategy for multiple inverter-interfaced distributed generators to compensate the harmonic currents is discussed. The coordination strategy is realized by distributing the harmonic compensation participation index to individual distributed generators. The harmonic compensation participation index can be determined by the amount of remaining power generation capacity of each distributed generator. Simulation results based on switching-level inverter models show that the proposed harmonic detection method has good performance and the coordination strategy can improve harmonic problems efficiently.

• 대한전기학회논문지:전력기술부문A
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• 제48권1호
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• pp.16-21
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• 1999

The analysis of distribution line faults is essential to the proper protections of the power system. A high impedance fault test, which was carried in Korean electric power systems, it was found that a arcing phenomenon occurred during the high level portion of conductor voltage in each cycle. In this paper, we propose a new method for detection of high impedance faults, which uses the arcing fault current difference during high voltage and low voltage portion of conductor voltage waveform. To extract this difference, we diveded one cycle fault current into equal spanned four data windows according to the magnitude of voltage waveform and applied fast fourier transform(FFT) to each data window. The frequency spectrum of current wavefrom in each portion are used as the inputs of neural network and is trained to detect high impedance faults. The proposed method shows improved accuracy when applied to staged fault data and fault-like load.

• KIEE International Transactions on Power Engineering
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• 제3A권2호
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• pp.85-92
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• 2003

When a current transformer (CT) is saturated, the wave-shape of the secondary current is distorted and contains points of inflection, which correspond to the start or end of each saturation period. Discontinuity in the first-difference function of the current arises at points of inflection, where the second and third differences convert into pulses that can be used to detect saturation. This paper describes the design and evaluation of a CT saturation detection technique using the third-difference function and includes the countermeasure for a spike signal. Test results clearly demonstrate that the algorithm successfully detects the start and end of each saturation period irrespective of the remanent flux and magnetization inductance in the saturated region. This paper concludes by describing the results of hardware implementation of the algorithm using a DSP.

• 전력전자학회논문지
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• 제17권5호
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• pp.445-452
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• 2012

The impurity detection method applied to existing discriminated the normality(R, L, C) and impurity(Metal) load using mutual RFID/ID method in the contactless power supply in which the primary side and the secondary side are completely separation by using the contactless transformer. However, this kind of system is caused the high cost of the system and complexity of control. Therefore, in this paper was proposed the contact-less power transfer using the primary current that determine normality or impurity load by compare the primary current Amplitude to reference quantity value and design the 3[W] contact-less power transfer and conduct an experiment for demonstrate the validity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.417-420
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• 2003

In this paper, we have designed the ground faults detection and disconnection algorithm at normal rendition of AC 120V to 240V rating voltage. Ground faults in electrical network have the characteristics of low current, 60Hz frequency to 2kHz frequency. The load rendition are no load and 20A load. The controller have the trip level are 6mA with ground faults. Conventional controller does not have the miswiring condition. The Controller algorithm using pic16c71 microprotessor.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권1호
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• pp.26-32
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• 2005

Rotor position information is essential in the operation of the switched reluctance motor(SRM) drive for generation the phase current switching signals. When an incremental encoder is used as a rotor position sensor, the initial rotor position can not be detected. Some sensorless rotor position estimation methods also have the same problem. In these systems, to initially align the rotor, the forced alignment method has a delay and reverse rotation before the motor can start. Therefore it can not be acceptable for unidirectional drive systems. So the forced alignment method is not desirable in all drive systems and the research on the SRM drives should be directed to a system without rotor alignment. In this paper, a new detection method of initial rotor position using the rate of change of current is suggested. Firstly, di/dt versus θ/sub R/ reference table, which is the relation between the rate of change of current and rotor position, is generated and then the squared Euclidean distance method is used to estimate the rotor position based on the table. The simulated and experimental results are presented demonstrating the feasibility and accuracy of this method.

• 상하수도학회지
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• 제34권5호
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• pp.357-371
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• 2020

Microplastics have become a rising issue in due to its detection in oceans, rivers, and tap water. Although a large number of studies have been conducted on the detection and quantification in various water bodies, the number of research conducted on the removal and treatment of microplastics are still comparatively low. In the current research, the inflow and removal of microplastics were investigated for various drinking water treatment plants around the world. Addition to the investigation of filed research, a survey was also conducted on the current research trend on microplastic removal for different treatment processes in the drinking water treatment plants. This includes the researches conducted on coagulation/flocculation, sedimentation, dissolved air flotation, sand filtration and disinfection processes. The survey indicated mechanisms of microplastic removal in each process followed by the removal characteristics under various conditions. Limitations of current researches were also mentioned, regarding the gap between the laboratory experimental conditions and field conditions of drinking water treatment plants. We hope that the current review will aid in the understanding of current research needs in the field of microplastic removal in drinking water treatment.

• 한국통신학회논문지
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• 제27권1C호
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• pp.96-102
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• 2002

전류 테스팅은 전류 테스팅은 CMOS 회로의 합선고장을 효과적으로 검출할 수 있는 기법이다. 그러나 합선고장의 복잡도가 O($n^2$)이고, 또한 전류 테스트 방식이 전압 테스트 방식에 비해서 상대적으로 긴 테스트 시간이 필요하기 때문에 두 합선된 노드가 항상 같은 값을 가지는 노드를 찾아내어 제거하는 효율적인 무해고장 검출기법이 필요하다. 이러한 무해고장은 보다 정확한 고장 검출율을 위해서 ATPG 툴을 이용하여 검출될 수 있어야 한다. 본 논문에서는 효율적인 전류 테스트를 위한 객체 기반의 무해고장 검출기법을 제안한다. ISCAS 벤치마크 회로에 대한 실험을 통해서 제안된 기법이 기존의 다른 방식보다 더 효과적임을 보여주었다.

• 한국압력기기공학회 논문집
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• 제11권2호
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• pp.61-67
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• 2015

3D FEM modeling based on 3D CAD data has been performed to evaluate the efficiency of CP system in a real operating nuclear power plant. The results of it successfully produced sophisticated profiles of electrolytic potential and current distributions in the soil of an interested area. This technology is expected to be a breakthrough for detection technology of damages on buried pipes when it comes into combining with a brand of area potential earth current (APEC) and ground penetrated radar (GPR) technologies. 2D current distribution and 2D current vectors on the earth surface from the APEC survey will be used as boundary conditions with exact 3D geometry data resulting in visualization of locations and extents of corrosion damages on the buried pipes in nuclear power plants.

• 산업기술연구
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• 제27권B호
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• pp.91-96
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• 2007

Electrical impedance tomography (EIT) is a technique for determining the electrical conductivity and permittivity distribution within the interior of a body from measurements made on its surface. One recent application area of the EIT is the detection of breast cancer by imaging the conductivity and permittivity distribution inside the breast. The present standard for breast cancer detection is X-ray mammography, and it is desirable that EIT and X-ray mammography use the same geometry. A forward model of a simplified mammography geometry for EIT imaging was proposed earlier. In this paper, we propose an iterative algorithm for computing the current pattern that will be applied to the electrodes. The current pattern applied to the electrodes influences the voltages measured on the electrodes. Since the measured voltage data is going to be used in the impedance imaging computation, it is desirable to apply currents that result in the largest possible voltage signal. We compute the eigenfunctions for a homogenous medium that will be applied as current patterns to the electrodes. The algorithm for the computation of the eigenfunctions is presented. The convergence of the algorithm is shown by computing the eigencurrent of the simplified mammography geometry.