• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.115-118
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• 2000

In case of developing new motor, many examinations was tested to decide a motor efficiency and reliability. To give reliability judgment, traction motor winding insulation was tested by electrical method after appling electrical, heat, mechanical, environmental stress. In this study, stator form-wound winding of traction motor in urban transit E.M.U was tested by accelerative thermal degradation test. Stator form-wound winding was tested on the accelerative degradation composed of heat, vibration, moisture, overvoltage and researched insulation resistance, dielectric loss, partial discharge for insulation degradation properties, evaluated withstand voltage. Degradation temperature was $230[^\circ{C}]$, $250[^\circ{C}]$, $270[^\circ{C}]$, for stator form-wound winding respectively. On the test results of accelerative thermal degradation, insulation properties were relied all temperature until 10 times and expected life was evaluated by the rule of reducing $10[^\circ{C}]$ life into halves. Expected life was 31.8 years. It is guaranteed insulation reliability because of exceeding 25 years life times as considering.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.699-702
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• 2002

A DC current sensor is disclosed in which two pairs of saturable cores are provided so as enclose a conductor carrying a direct current to be measured. On each of the saturable cores, a bias winding, a feedback winding and an output winding are wound. Circuit for detection of an asymmetry in the magnetization current, generated by a reference alternating voltage, in a signal-conditioner. The reference alternating voltage is fed to the respective series circuits such that no resultant induction current is induced in the modulating current. The voltages over the resistor form input signals for two peak value detectors, the strength of the output signal of which represents the degree of asymmetry of magnetization current. This paper describes the development a DC current sensor and its signal-conditioner.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2073-2074
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• 2011

In this study, an algorithm for diagnosis of dc motor with winding open fault is suggested. A dc motor used in this paper, is consisted of a permanent magnet field stator, double 16-turn series winding rotating armature with 12-slot, brush and 12-commutator, etc. A current signal of dc motor which has brushes and commutatorswas considered for fault diagnosis. By commutation, this current signal shows different wave form according to the fault condition of the motor. In this study, operation of the data was easily through simplification of the current signal by the signal processing. Computation method is presented reference value($C_{dv}$) for diagnosis of winding open fault and verified through experiments that can be diagnosed using the reference value($C_{dv}$).

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.735-737
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• 2000

An axial-flux permanent-magnet machine(AFPM) topology with coreless winding is proposed. In the proposed AFPM configuration. the winding consists of a hexagon-shaped coils encapsulated in fiber-reinforced epoxy resin. Due to the lack of the iron core. the overall machine structure has high compactness and lightness. The simplified design calculation of the back emf was obtained. In this study, motor design was carried out using the software package Maxwell. This paper discusses the basic design of coil winding of AFPM motor. Experimental results were taken form a prototype machine rated 0.4 Nm, 2000 rpm.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.957-959
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• 2005

A noise reduction equipment in power systems was device combined in a passive element such as the form of L, R and C. A analysis of frequency characteristics for the transformer models shall be considered the additional capacitance between the windings($C_{ps}$), terminals($C_s$), and winding-ground($C_g$). A noise in transformer is modeled by take account into the different frequency. In case of the high frequency, transformer windings with stray capacitance have lower impedance. Therefore a noise is transferred from primary winding to secondary winding. Noise Cut Transformer(NCT) was the noise reduction device and was normally single phase two-winding type transformer. We analyzed frequency characteristics using the nodal network analysis with the equivalent circuit and the simulation of the MATLAB.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.1
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• pp.13-18
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• 1999

To fabricate a 0.7 FJ, 100 kVA $\mu$SMES device for improving power quality in sensitive electric loads, we developed a design code for a $\mu$SMES device and designed the 0.7 MJ $\mu$SMES device by using it. In this study special emphasis was placed in influence of winding tensions on quench currents of superconducting coils because dry superconducting coils are usually quenched by local disturbances due to strand motions. We first investigated the quench currents of a few kA class superconducting cables for various winding tensions experimentally. To prove the validity of the code and develop all techniques related to fabrication and test of the 0.7 MJ $\mu$SMES device, a smaller size superconducting coil was wound with high winding tension of about 15 kgf/$mm^2$ based on the test results of superconducting cables and tested. It isshown form the test results that designed parameters for the smaller size superconducting coil are in good agreements with measured ones and the quench current of the coil with high winding tension reaches nearly to the critical current of the superconducting cable without any training effects.

• Journal of Power Electronics
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• v.12 no.6
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• pp.960-973
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• 2012

The winding loss analysis of a flyback transformer is difficult and ambiguous because the primary side current and the secondary side current differs both in shape and phase, especially for DCM (Discontinuous Conduction Mode) operation. Meanwhile, the fringing field caused by the air gaps further makes the traditional 1-D loss analysis model not directly applicable. The paper gives a thorough investigation into the phase shift of winding currents, which indicates that the phase shift of the high order harmonics is still close to $180^{\circ}$ out-of-phase. Based on the analysis, a simplified 2-D winding loss analytical model for flyback transformers considering the effects of low order harmonics is proposed. By neglecting the y components of the fringing field, the proposed model has an acceptable accuracy and a simple form that is similar to the conventional 1-D model. The power loss calculated with the proposed analysis model is verified by FEA (Finite Element Analysis) simulations and experimental results.

• 전기의세계
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• v.25 no.5
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• pp.75-78
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• 1976

The most difficult problem encountered in impulse test of transformer is the determination of exact fauly for coil layer short. This paper is to establish one of improved standards in the above case by means of wave form analysis, based on the equivalent circuits and experimental investigation. During the fault occurs, the local oscillation in fault circuit is applicable where as the reflection wave is utilized to the main circuit. The result current wave form at neutral impeadance point is similar to the wave form by impulse test and has the singular wave form respectively.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.452-454
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• 1999

In this paper, sample coils for stator form-wound winding of traction motor were made for the accelerative thermal degradation composed of heat, vibration, moisture and overvoltage. In progress of test periods, diagnosis tests such as insulation resistance, dielectric loss and partial discharge were investigated. Reliability and expected life were evaluated on the insulation system for 200 class traction motor considering various environmental stress.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.93-101
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• 2002

In this study, the stator form-winding sample coils based on silicone resin and polyimide were made for fault prediction and reliability estimation on the C-Class(200$\^{C}$ ) insulation system of traction motors. The complex accelerative degradation was periodically performed during 10 cycles, which was composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, the condition diagnosis test such as insulation resistance '||'&'||' polarization index, capacitance '||'&'||' dielectric loss and partial discharge properties were investigated in the temperature range of 20 ∼ 160$\^{C}$. Relationship among condition diagnosis tests was analyzed to find a dominative degradation factor and an insulation state at end-life point.