• Journal of Power Electronics
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• v.13 no.1
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• pp.77-85
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• 2013

This paper proposes a new dead time compensation method of independent six-phase permanent magnet synchronous motors (IS-PMSM). The current of the independent phase machines contains odd-numbered harmonics because of the dead time and the nonlinear characteristics of the switching devices. By using the d-q-n three-dimensional vector analysis, these harmonics can be extracted at the n-axis current. Thus, the current distortion can be compensated by controlling the n-axis current of the IS-PMSM to zero. The proposed method is simple and can be easily implemented without additional hardware setup. The validity of the proposed compensation method is verified with simulations and several experiments.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1380-1392
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• 2019

Input filters are very important to matrix converters (MCs). They are used to improve grid side current waveform quality and to reduce the input voltage distortion supplied to the grid side. Due to the effects of the input filter and the output power, the grid side power factor (PF) is not at unity when the input power factor angle is zero. In this paper, the displacement angle between the grid side phase current and the phase voltage affected by the input filter parameters and output power is analyzed. Based on this, a new grid side PF unity compensation method implemented in the indirect space vector pulse width modulation (ISVPWM) method is presented, which has a larger compensation angle than the traditional compensation method, showing a higher grid side PF at unity in a wide output power range. Simulation and experimental results verify that the analysis of the displacement angle between the grid side phase current and the phase voltage affected by the input filter and output power is right and that the proposed compensation method has a better grid side PF at unity.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.966-973
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• 2011

Power distribution onboard vessel is typically configured as ungrounded system due to the ability to continuously supply electric power even when an earth fault occurs. The impedance connections between 3 phase power lines and hull cause the line-to-hull voltages to become unstable and increased in case the impedances are unbalanced, bringing the situation susceptible to electric shock and deterioration of insulation material. Also the line-to-hull voltage can reach to a certain maximum value in the steady state depending on the distributed capacitances and grounding resistances between lines and hull. This study suggests how to find and calculate the maximum line-to-hull voltage in view of magnitude and phase angle based on the vector diagram.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.619-622
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• 2001

In this paper, an efficient approach to classification of transient and harmonic disturbances in power systems is proposed. First, the Stop-and-Go CA CFAR Detector is utilized to detect a disturbance from the power signals which are mixed with other disturbances and noise. Then, (i) Wigner Distribution, SVD(Singular Value Decomposition) and Fisher´s Criterion (ii) DWT and Fisher´s Criterion, are applied to extract an efficient feature vector. For the classification procedure, a combined neural network classifier is proposed to classify each corresponding disturbance class. Finally, the 10 class data simulated by Matlab power system blockset are used to demonstrate the performance of the proposed classification system.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.19-22
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• 2004

In this paper, we present a way that can implement the vector control Algorithm of induction motor and PWM signal generation on the basis of Matlab Simulink environment. The overall system model is designed by Simulink toolbox for vector control of induction motor, and then implement experiment with the DS1103 board of dSPACE. Although we are not coding the system, it is capable of doing simulation and experiment simultaneously. That is why Matlab and dSPACE board compiler can generate the '*.c' and '*.obj' files on the designed system automatically. After considering about hardware structure and driving system in Ds1103 board we verify the availability of Proposed method through in a comparison/analysis between simulation and experiment.

• Journal of Power Electronics
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• v.10 no.6
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• pp.686-693
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• 2010

In this paper, a fault diagnosis method based on fuzzy logic for the three-parallel power converter in a wind turbine system is presented. The method can not only detect both open and short faults but can also identify faulty switching devices without additional voltage sensors or an analysis modeling of the system. The location of a faulty switch can be indicated by six-patterns of a stator current vector and the fault switching device detection is achieved by analyzing the current vector. A fault tolerant algorithm is also presented to maintain proper performance under faulty conditions. The reliability of the proposed fault detection technique has been proven by simulations and experiments with a 10kW simulator.

• Journal of Korea Port Economic Association
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• v.21 no.1
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• pp.133-151
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• 2005

The purpose of this paper is to investigate the international competition power between Korean ports and Chinese ports according to the port efficiency scores of DEA(Data Envelopment Analysis) by newly introducing the priority vector of AHP(Analytic Hierarchy Process) to the DEA method. Empirical analysis shows the followings: First, there was not big changes of DEA rankings when we use the input-oriented CCR and BCC models after introducing the AHP priority vectors to the input variables. Yantian Port's competition power was declined, but that of Busan Port was up in the BCC model. Second, there was some changes of DEA rankings when we use the output-oriented CCR and BCC models after introducing the AHP priority vectors to the output variables. Rankings of Dalian, Qingdao, Shanghai Ports were up. But Shekou, Yantian Ports showed the declined ranking position in the CCR model. In the BBC model, rankings of Shanghai and Busan Ports were up. But those of Shekou and Yantian Ports were declined. The main policy implication based on the findings of this study is that The Ministry of Maritime Affairs & Fisheries in Korea and China should introduce AHP and DEA approaches when they measure the international competition power by using the porrt efficiency scores of DEA.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1420-1425
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• 2012

Nowadays, Interior permanent magnet synchronous motor(IPMSM) which having high power density is much used for the vehicles. However, IPMSM causes a lot of losses because of high-speed driving and high current density, and temperature rising by iron loss and copper loss could reduce torque characteristics and durability of IPMSM. Therefore, analysis about thermal characteristics of IPMSM is required at design stage. In this paper, temperature characteristics according to current vector control method were analyzed through calculate thermal equivalent circuit. And calculated results were verified through comparing with the experiments.

• Structural Engineering and Mechanics
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• v.3 no.2
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• pp.173-183
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• 1995

A new vector algorithm is presented for computing the stiffness matrices of layered reinforced concrete shell elements. Each element stiffness matrix is represented in terms of three vector arrays of lengths 78, 96 and 36, respectively. One element stiffness matrix is calculated at a time without interruption in the vector calculations for the uncracked or cracked elements. It is shown that the present algorithm is 1.1 to 7.3 times more efficient then a previous algorithm developed by us on a Cray Y-MP supercomputer.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.172-183
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• 2006

This paper analyzes instantaneous power compensation theory through comparing p-q theory and cross-vector theory which were proposed by Akagi and Nabae respectively in three-phase four-wire systems. The two compensation theories are identical when there is no zero-sequence voltage component in three-phase three-wire systems, However, when the zero-sequence voltage and/or current components exist in three-phase four-wire systems, the two compensation theories we different in definition on instantaneous real power and instantaneous imaginary power. Based on the analysis, this paper presents instantaneous power compensation method that can eliminate neutral current completely without using energy storage element when the zero-sequence current and voltage components exist in three-phase four-wire systems.