• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.968-970
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• 2001

Recently, the power supply equipments have tendency to take multiple feedback loop paths. In this paper the state space averaging technique is applied for the analysis of flyback type current mode control circuit. We made real converter for the gurantee of stable output characteristic and proper design of feedback circuit. The validity of proposed method is verified from test results. The improvement of stability is confirmed by sinusoidal signal injection method with isolated transformer. It is known that phase margin is sufficient and gain crossover frequency $f_c$ is nearly 1/5 of switching frequency $f_s$, from the experimental result with frequency response analyzer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.570-572
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• 1999

An equivalent circuit model of vehicle charging-discharging system for simulation is developed. The vehicle electric power system consists of alternator and battery. The alternator must have adequate capacity for providing electric energy to all loads, and the battery supports the alternator by offering insufficient energy when the alternator output energy is not enough. The alternator model is simplified for the use of characteristic curve, which was provided by its manufacturer, and the battery model is separated in charging mode and discharging mode because of its complex characteristics. Developed circuit model is validated by comparing the simulation data and real experimental data.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.93-97
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• 2005

This paper proposes a design of stepper motor control in microstep driven mode using FPGA (Field Programmable Gate Array) for hardware implementation. The methods to drive stepper motor in microstep excitation mode are to control of the controlling currents in each phase windings of stepper motor with reference signals. These reference signals are used for controlling the current levels, the required variation of current levels with rotor position can be obtained from the ideal linear or sinusoidal approximations to the static torque-displacement ($T-{\theta}$) characteristic curve. In addition, the hardware implementation of stepper motor controller can be designed uses VHDL (Very high speed integrated circuits Hardware Description Language) and synthesis using an Altera FPGA, FLEX10K family, EPF10K20RC240-4 device as target technology and use MAX+PlusII program for overall development. A multi-stack variable-reluctance stepper motor of Sanyo Denki is used in the experiments.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2552-2556
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• 2005

In general, the forklift driven by DC motor drive system is used in the industrial field. Classically, the DC motor is controlled by current control using proportion control method, by output torque following the load on the plane like a manual operation. But in the industrial field, the forklift is demanded the robust drive mode. Some cases of the mode, there aretrouble in torque control following slope capacity. The control is sensitive concerning about slope angle and output speed, various control method is studied for stability of speed control. In this paper, I apply current control for the self-tuning using the fuzzy controller to obtain robust, stable speed control and use stable, high efficiency control using DSP as main controller for high speed processor, embody dynamic characteristic of control compared the PI controller to the fuzzy controller.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.469-472
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• 1998

InGaAsP/InP ridge waveguide(RWG) distributed feedback(DFB) lasers (LD) operating at 1.55.mu.m were fabricated by a two step MOCVD process. The CW laser threshold and the slope efficiency from these lasers are 22.5mA and 0.127mW/MA perfacet at room temperature. Single longitudinal mode operation with side mode suppression of more than 30dB is obtained at 5mW. The temperature sensitivity and characteristic temperature (T$_{0}$) from DFB lasers were obtained 1.0.angs./.deg. C and 50.3K between 20.deg. C and 70.deg. C, respectively.y.

• 전자공학회논문지S
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• 제34S권11호
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• pp.34-42
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• 1997

In this paper, we show an optimal structure of impedance control in high density layouts ina high multilayers PCB. The impedance control in a high multilayers FR-4 PCB is very portant isue because a dielectric layer's thickness is very thin. Especially, odd mode impedance control is more difficult than characteristic impedance control in high multilayers PCB. So, we show an optimal structure of odd mode impedance control in that dielectric thickness is about 0.1mm with limited state and discuss multilayers PCB's for swich circuti pack and backplane in developing algorith scale ATM witching system in next time.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.743-746
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• 2006

We have demonstrated a transflective liquid crystal display (LCD) with a single cell gap in a patterned vertically aligned mode. In our configuration, the different electrode structure in a transmissive and a reflective part was suggested to compensate an optical path difference of each region. As the result, the similar electro-optic characteristic of each region was obtained which results in an enhanced performance of the device. Moreover, suggested technique can be highly effective to realize the practical transflective LCD due to the simple fabrication process.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.539-542
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• 2003

We have studied cell gap-dependent electrode-optic characteristics of the FFS mode using the LC with negative dielectric anisotropy. In case of a small cell gap of 2 ${\mu}m$, the transmittance at the center of pixel and common electrodes is low due to stronger influence of surface anchoring that holds the LC to the initial state than twisting force induced by neighboring LCs. In case of a large cell gap of 4 ${\mu}m$, the influence of surface anchoring force becomes weak so that the LCs at the center of pixel and common electrode can be twisted enough by applied voltage, giving rise to high transmittance. Therefore, we conclude that the light efficiency in the device is dependent on the cell gap.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.93-96
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• 2004

An ultrasonic linear motor was composed of a slider and a stator vibrator including piezoelectric material and elastic material. The ultrasonic linear motors mainly consist of an ultrasonic vibrator which generates elliptical oscillations. L1-B4 ultrasonic linear motor use longitudinal and bending multi-vibration. In order to design stators which has high efficiency and driving characteristics, The finite element method was used to optimize dimension of ultrasonic vibrator and direction of vibratory displacement. stator vibrator of respectively width 3, 5, 7[mm] was fabricated and experimented. as results When width was 5[mm], the driving characteristics was good.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.730-733
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• 2004

An ultrasonic linear motor was composed af a slider and a stator vibrator including piezoelectric material and elastic material. The ultrasonic linear motors mainly consist of an ultrasonic vibrator which generates elliptical oscillations. $L_1-B4$ ultrasonic linear motor use longitudinal and bending multi-vibration. In order to design stators which has high efficiency and diriving characteristics. The finite element method was used to optimize dimension of ultrasonic vibrator and direction of vibratory displacement. stator vibrator of respectively width 3, 5, 7[mm] was fabricated an experimented. as results When width was 5[mm], the driving characteristics was good