• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.342-344
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• 1999

This paper presents the analysis of core losses in capacitor-run single phase induction motors using the finite element methods. The double revolving field theory can be used for the analysis to assess the quantitative and qualitative performance of the single-phase induction motor. But it is difficult to evaluate accurately the core losses. It is more difficult to segregate stator and rotor core losses at no-load and load conditions. Numerical analysis such as FEM can be used effectively for the accurate calculation of core losses and motors performances. In this paper, the coupling method of core loss characteristic equation and FEM are proposed for the accurate calculation of core losses in the stator and rotor. The FFT is also used to calculate fundamental and harmonic components in the yoke and teeth parts of motor.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.11
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• pp.1691-1696
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• 2013

In this paper, an analysis of behavior is performed in the circular hybrid energy harvesting device. This analysis of behavior is to confirm with or without an existence of nonlinear system because its system is required to produce the more energy. To do this, first of all the phase portrait is reconstructed through Taken's embedding method, and then Poincare map is organized by using phase portrait and finally Lyapunov exponent is analyzed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1123-1129
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• 2012

This paper presents the fast steady state analysis using time-stepping finite element method for a high power three-phase transformer. The high power transformer spends huge computational cost of the time-stepping finite element method. It is because that the high power transformer requires a lot of time to reach steady state by its large inductance component. In order to reduce computational cost, in this paper, the adaptive time-step control algorithm combined with the embedded 2nd 4th singly diagonally implicit Runge-Kutta method and the analysis strategy using variation of the winding resistance are studied, and their numerical results are compared with those from the typical time-stepping finite element method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.29-38
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• 2005

The track pull-in behavior analysis in an optical disk drive (ODD) using plane phase and the evaluations for effecting parameters of it are discussed. Track pull-in, track capture procedure to do track following control, is a key factor to increase data transfer rate. First, the relative velocity between the beam spot of an optical pick-up and the target track of an optical disk is analyzed during the track pull-in procedure. In this process, it is showed that the track error signal has nonlinear characteristics which are depending on the time. Second, Runge-Kutta method to solve the nonlinear equation is applied to find the track pull-in behavior, and some optimal parameters to get stable and fast pull-in condition are obtained. Then, the phase plane analysis for track pull-in procedure is presented. Finally, some comments for the simulated results are discussed briefly.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.5
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• pp.604-610
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• 2014

In this paper, the analysis and the experiment of independent multi-phase BLDC motor are performed. The back-emf, iron loss analysis are performed by the finite element method and compared with experimental results. The independent multi-phase BLDC motor is manufactured and to measure the efficiency of the motor, evaluation system is also manufactured including the load generator. By comparing the analytic and the experimental results, the effectiveness of the analysis model is verified when calculating the efficiency of the motor.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.544-550
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• 2014

In this paper, we have proposed a novel method which can analysis the direction finding ambiguity analysis for array geometry in 3 channel and 4 channel multiple baseline direction finding system. Generally, the direction finding ambiguity in the 3 element and 4 element phase interferometer direction finding system is calculated by the simulation for the array spacing or by the probability with the selected antenna array spacing. There are some restrictions to obtain the ambiguity of direction finding system in these methods. The former performs a simulation with every antenna array spacing and the latter calculates the ambiguity with the selected antenna array spacing. To overcome those restrictions, This paper proposed the novel method to calculate the ambiguity using the imaginary antenna array spacing and the phase difference prior to the modular operation in direction finder. Using the proposed method, we obtain the ambiguity probability for each of array geometry composed of multiple baseline. After performing the simulation with the selected antenna array spacing to verify the proposed method, we compared the calculated result data with the simulation data.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.1
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• pp.59-66
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• 1998

The combustion instability analysis of solid propellants is generally done by the simplified governing equations for chemically inert condensed phase region with QSHOD assumption. Since the gas phase and surface reaction layer can be more rapidly relaxed to the external perturbations than the condensed phase, these regions are treated as quasi-steady manner in the analysis. In this paper, the classical ZN(Zeldovic-Novozhilov)approach was re-examined with the presence of radiation augmented burning enhancement in the combustion. Also, the surface reaction was assumed to partially absorb the incident radiant heat fluxes and pass the remaining to the chemically inert condensed phase. As a result of the analysis, the burning rate response function was obtained which consists of a pressure response function and a radiation response function. The response function was shown to be able to predict the results of T-burner tests.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.8-17
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• 2019

The main purpose of this study isto explore the potential of affective computing (AC) platforms in education through two phases ofresearch: Phase I - platform analysis and Phase II - classification of academic emotions. In Phase I, the results indicate that the existing affective analysis platforms can be largely classified into four types according to the emotion detecting methods: (a) facial expression-based platforms, (b) biometric-based platforms, (c) text/verbal tone-based platforms, and (c) mixed methods platforms. In Phase II, we conducted an in-depth analysis of the emotional experience that a learner encounters in online video-based learning in order to establish the basis for a new classification system of online learner's emotions. Overall, positive emotions were shown more frequently and longer than negative emotions. We categorized positive emotions into three groups based on the facial expression data: (a) confidence; (b) excitement, enjoyment, and pleasure; and (c) aspiration, enthusiasm, and expectation. The same method was used to categorize negative emotions into four groups: (a) fear and anxiety, (b) embarrassment and shame, (c) frustration and alienation, and (d) boredom. Drawn from the results, we proposed a new classification scheme that can be used to measure and analyze how learners in online learning environments experience various positive and negative emotions with the indicators of facial expressions.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.4
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• pp.9-16
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• 2018

This study described partial discharge(PD) distribution analysis between the XLPE(Cross-Linked PolyEthylene)and EPDM(Ethylene Propylene Diene Monomer) interface with unsupervised classification. The ${\phi}-q-n$ patterns were analyzed using phase resolved partial discharge(PRPD). K-means cluster analysis forms a cluster based on similarities and distances among scattered individuals, and analyzes the characteristics of the formed clusters, dividing the multivariate data into several groups according to the similarity of each characteristic, Is a statistical analysis that makes it easier to navigate. It was confirmed that the phase angle of the cluster with the maximum discharge charge was concentrated around $0^{\circ}$ and $180^{\circ}$ at 30 kV after the initial phase distribution localized around $90^{\circ}$ and $300^{\circ}$ expanded to the whole phase angle according to the voltage rise. The Euclidean distance between the center of gravity and the discharge charge in the ${\Phi}-q$ cluster increased with increasing applied voltage.

• Journal of Power Electronics
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• v.9 no.5
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• pp.736-747
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• 2009

A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.