• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.38-45
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• 2012

A novel kind of switched reluctance motor (SRM) with short flux path is proposed in this paper. Phase excitation in the SRM gives short flux paths, hence reducing the magnetomotive force required to drive the machine, resulting in significant reduction of copper wire and core losses compared to the typical SRM with diametric circulation of magnetic flux. To verify the performance, the characteristics analysis of a double-stator SRM, a 6/5 SRM with C-core structure, and a 4/5 two-phase SRM, which all have short flux paths, and a comparison with conventional SR motors are executed. The comparison demonstrates that the proposed motor offers some advantages in terms of torque and efficiency.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.4
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• pp.188-200
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• 2001

This paper presents a technique for reconstructing converter line currents using the information from a single current sensor in the DC-link for voltage-source PWM converters. When three-Phase input currents cannot be reconstructed, three methods to acquire the input current are compared. Two of them are methods of modifying the switching state (I, II), another is a method of using the predictive state observer. Also, compensation of sampling delay, and a simultaneous sample value of input currents in the center of a switching period are included. Suitable criteria for the comparison are identified, and the differences in the performance of these methods are investigated through experimental results for a typical V-S PWM converter rated at 10kVA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.539-544
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• 2016

This paper improves Sherman's two-pulse method for angle estimation of two unresolved targets in phase comparison monopulse radar. The proposed method provides the angle information with only a single-pulse measurement instead of two pulses. The proposed method can estimate a single-target angle by single-target indicator, in contrast with previous techniques. The accuracy of angle estimation for proposed method is demonstrated by simulations.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.721-722
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• 2008

This paper deals with comparison and analysis for rotor losses of permanent magnet synchronous generator using phase current harmonic analysis according to dc and ac load. On the basis of analytical field analysis, the rotor losses are analysed. Particularly, rated speed and ac load and the rated speed and dc load conditions are considered. This paper compared rotor losses considered dc load with rotor losses considered ac load. Although our analytical modes is low speed, the rotor losses must be considered by results.

• Journal of Power Electronics
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• v.12 no.6
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• pp.851-858
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• 2012

This paper presents resonant inverter tuning for current source parallel resonant induction heating systems based on a new self oscillating switching technique. The phase error is suppressed in a wide range of operating frequencies in comparison with Phase Locked Loop (PLL) techniques. The proposed switching method has the capability of tuning under fast changes in the resonant frequency. According to this switching method, a multi-frequency induction heating (IH) system is proposed by using a single inverter. In comparison with multi-level inverter based IH systems, the advantages of this technique are its simple structure, better transients and wide range of operating frequencies. A laboratory prototype was built with an operating frequency of 35 kHz to 55 kHz and 300 W of output power. The performance of the IH system shows the validity of the new switching technique.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.31-32
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• 2007

In this paper, a fault section detection method is proposed for ungrounded system in the case of a single line-to-ground fault. A conventional method is used for faulted feeder selection according to the angular relationship between zero-sequence currents of the feeders and zero-sequence voltage of the system. Fault section detection is based on the comparison of phase angle of zero-sequence current. Proposed method has been testified in a demo system by Matlab/Simulink simulations. Based on Distribution Automation System(DAS), Feeder Remote Terminal Unit(FRTU) is used to collect those necessary data, at present a demo system is under developing using Manufacturing Message Specification (MMS) in IEC61850 standard.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.17-19
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• 2010

In this paper, new PWM method is proposed to reduce input current THD of PWM Rectifier. In general, the carrier comparison PWM method is used for PWM rectifier in which triangle wave is used as a carrier wave. However, large d-axis current ripple by this method can be a source of large THD. In this paper, new carrier comparison PWM method is proposed in which sawtooth wave is used as a carrier wave. Depending on the phase of the voltage commands, the rising or falling sawtooth wave is selected to reduce the THD. The simulation results verified the performance of the proposed method.

• Journal of the Korean Society of Combustion
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• v.7 no.4
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• pp.1-9
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• 2002

The morphology of deposits on $15-{\mu}m$ thin SiC filaments has been investigated with SEM and compared with UV-excited laser induced broadband fluorescences in co-flowing, propane laminar diffusion flames in a reduced oxidizer environment. The homogeneous morphology of droplet-like deposits inner flame zone and the agglomeration of condensed-phase deposits and the transition to soots from grown up droplet-like precursors with approaching the flame surface can be observed in a barely sooting flame. The average size of the mature soots deposited in the luminous flame edge is scarcely dependent on their axial position in a confined flame under reduced oxidizer condition. A double structure of PAH fluorescence is observed in near-extinction flames with further decreasing of oxidizer. A comparison of the PAH fluorescence with the morphologies of deposits indicates that appearance of the "dark" hollow zone is caused by a decreased number density of developed liquid-phase large molecules and the outer weak fluorescence zone is caused by the diffusion of gas-phase small molecules.

• Journal of Pharmaceutical Investigation
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• v.37 no.2
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• pp.85-94
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• 2007

The objective of this study is to prepare a stable delivery systems containing polyethoxylated retinamide(PERA) - derivatives of retinoic acid, effective anti-wrinkle and anti-acne agent. Cubic liquid crystalline phase gel (CLCPG) and cubosomes containing various concentrations of PERA were prepared to investigate the physicochemical properties. Furthermore, stability and transdermal absorption efficacy of the CLCPG containing PERA were investigated in comparison with oil-in-water (O/W) emulsions which are predominantly used as a topical formulation. CLCPG increase the stability of PERA in comparison with O/W emulsion. For tropical application, CLCPG containing PERA shows higher moisturizing effect than that of O/W emulsion. In skin permeation test, CLCPG shows higher PERA deposit on epidermis. With its specific physicochemical property caused by the glyceryl oleate, CLCPG itself could be used for stabilizer of various actives and applied as an effective delivery system for topical application. Cubosome, nano-sized dispersed CLCPG, is also expected to be applied in a various field of industry like food, cosmetics and pharmaceuticals.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.484-490
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• 2008

In this paper, an integrated fault section detection and isolation strategy is proposed based on the application of the Distribution Automation System(DAS) utilizing advanced IT and communication technologies. The Feeder Remote Terminal Unit(FRTU) has been widely used to collect data in the Korean distribution system. The achieved data is adopted in this method for detecting multiple fault types. Especially in the case of single phase-to-ground fault, the fault section is detected by comparison of the zero-sequence current phase angle. The test results have verified the effectiveness of the proposed method in a radial distribution system through extensive simulations in Matlab/Simulink. Furthermore, a communication-based demo system identical to the simulation model has been developed, and it can be applied as an online monitoring and control program for fault section detection and isolation.