• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1873-1878
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• 1991

An high-speed isothermal calorimeter which can trace the progress of a liquid phase reversible reaction was constructed using analog and digital computer. By means of a set point change of the calorimeter, the thermal energy capacity and the heat of reaction in reversible reaction mixture can be measured. The heat of reaction between 2-methyl furan and maleic anhydride and the heat capacities of the adduct were 61,200 J/mol and 2.38 J/ g K, respectively. Also reaction equilibrium constant and reaction rate constants can be estimated from the response curves of the calorimeter.

• 한국생산제조학회지
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• 제6권1호
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• pp.77-83
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• 1997

In this paper, we have studied internal quality including chemical compositions, microscopic structure and nonmetalic inclusion of test materials. We have analyzed dynamic characteristics of cutting force of milling including tensile strength value, hardness etc. Test materials are used in the tempered carbon steel and the non-tempered carbon steel. The obtained results are as follows: 1. In analyzing internal quality, the tempered carbon steel have typical martensite structure and the non-tempered carbon steel have ferrite + pearlite structure. 2. Yield strength, tensile strength and hardness value are in the non-tempered carbon steel but elongation is maximum value in the tempered carbon steel. 3. Cutting force is smaller non-tempered carbon steel than tempered carbon steel when feed speed and depth on cut is constant. 4. Cutting force is smaller non-tempered carbon steel than tempered carbon steel when cutting speed and depth of cut is constant.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.641-644
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• 1991

Constant slip frequency operation of linear infliction motor is essential for the stable levitation. Control scheme for the constant slip frequency with general purpose frequency inverter is proposed, Speed sensing scheme with proximitity switch for the speed feedback is also proposed. Optimal slip frequency, at which normal force is equal to 0, is selected by the experiment. This slip frequency is a comand to the controller. It shows good characteristic during acceleration and deceleration.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.600-604
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• 1991

In this paper, an advanced PWM modulation strategy for driving a variable-speed induction motor is introduced. According to this method, the technique of efficiently eliminating harmonics component is achived. A switching pattern was computed making use of the near-proportionality of voltage and frequency in AC machines operating with constant flux. At low magnitudes and low frequencies of the foundamental, many more harmonics are eliminated than at high magnitudes and frequencies. In order to keep the inverter switching frequency constant over the output frequency range, chopping times diminishes as the frequency of the fundamental increases.

• 전기학회논문지
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• 제59권12호
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• pp.2179-2189
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• 2010

This paper deals with analytical techniques for performance evaluation of small scaled wind power generator with outer permanent magnet rotor. In part (1), using transfer relations theorem, magnetic field distribution characteristics by PM and armature reaction field are derived. Moreover, electrical parameters such as back-EMF, inductance and resistance are calculated from the obtained field characteristic equations. The proposed analytical techniques are validated by nonlinear finite element method using commercial software 'Maxwell' and performance experiments of the manufactured generator. In part (2), generating characteristics analysis such as constant speed characteristics and constant resistive load characteristics, and performance evaluation according to variation of wind speed will be accomplished using the derived electrical parameters.

• 대한기계학회논문집B
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• 제32권7호
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• pp.513-517
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• 2008

A parametric study was made to understand the fundamentals of combustion of CNG fuel in a constant volume chamber in the respect of swirl effect, and the numbers of spark ignition. Optical devices were applied for the visualization of the physics of combustion, and combustion pressures and exhaust emission were measured at several equivalence ratios by controlling speeds of a swirling motor. When the speed of a swirling motor was raised the combustion conditions were improved. The corresponding maximum combustion pressure and heat release rate were increased and the speed of flame propagation was getting faster. This research may contribute to improve the performance of CNG engine and reduce emissions in future.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권7호
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• pp.356-363
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• 2001

A SRG (Switched Reluctance Generator) has many advantages such as high efficiency, low cost, high-speed capability and robustness compared with other of machine. But the control methods that have been adopted for SRGs are complicated. This paper proposes a simple control method using the PID controller which only controls turn-off angles while keeping turn-on angles of SRG constant. In order to keep the output voltage constant, the turn-off angle for load variations is controlled by using linearity between the generated current and turn-off angle since the reference generated current can be led through the voltage errors between the reference and the actual voltage. The suggested control method enhances the robustness of this system and simplifies the hardware and software by using only the voltage and the speed sensors. The proposed method is verified by experiments.

• Journal of Power Electronics
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• 제10권5호
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• pp.563-571
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• 2010

A model of an advanced aircraft electric power system is developed and studied under variable-speed constant-frequency (VSCF) operation. The frequency of the generator's output voltage is varied from 400-Hz to 800-Hz for different loading scenarios. Power conversions are obtained using 12-pulse power converters. To reduce the harmonic contents of the generator output waveforms, two high-pass passive filters are designed and installed one at a time at the generator terminals. The performance of the two passive filters is compared according to their losses and effectiveness. The power quality characteristics of the studied VSCF aircraft electric power system are presented and the effectiveness of the proposed filter is demonstrated through compliance with the newly published aircraft electrical standards MIL-STD-704F.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.62-64
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• 2007

This paper deals with design of high speed linear switched reluctance motor(LSRM). First, we derived design factor from pole arc ratio of stator and mover, and calculated time constant using inductance and resistance. Second, we decided design parameter from design factor using time constant. Finally, analyze characteristics for LSRM using finite element analysis.

• Journal of Advanced Marine Engineering and Technology
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• 제15권2호
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• pp.53-63
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• 1991

This study suggests a new type shaft generator driven by hydraulic power suitable for small size vessels. Since the shaft generator system is very easy to be affected by disturbances such as speed variation of main engine and load variation of the generator, a robust servo control must be implemented to obtain stable electric power with constant frequency. Thus, in this study two types of controller design method-the reference following optimal control method and robust servo control method-are adopted to the controller design. In the experiment, static and dynamic characteristics of the shaft generator system according to the variation of input frequency setting, the speed variation of the pump and the load variation of the generator are investigated. From the considerations on the computer simulation results and experimental results, it is ascertained that the shaft generator system proposed in this study has good control performances.