• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.6
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• pp.709-718
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• 2017

The installation of the elevator ARD(Automatic Rescue Device) system has been forced into law in these days in order to safely rescue passengers during power failure. The configuration of the ARD system consists of energy storage device, power converter and control systems. The EDLC(Electric Double Layer Capacitor) are used as energy storage device for rapid charge/discharge purposes. The power conditioning system (PCS) consists of bi-directional converter, 3-phase converter and control system. The dead-beat control system is adopted for most systems however it requires complex mathematical calculations, the high performance microprocessors are mandatory and thus it can be a cause of high manufacturing cost. In this paper the new control method for average current mode control is presented for simple structure. The control algorithm is applied to the single phase system and then expands to three phase system to meet the sysem requirements. The mathematical modeling using average modeling method is presented and analysed by PSIM computer simulation to verifie the validity of the proposed control methods.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.754-758
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• 2002

In the fuel-cell electric vehicle system, the low-voltage output of unit fuel-cell demands a number of cells to be stacked In series to produce a DC link voltage which is high enough to drive the vehicle inverter system. However, this increases the complexity of the fuel-cell control system. This paper presents a design of high-efficiency boost converter employing the average current-mode control, which is able to convert a low voltage of a fuel-cell generator with a small number of unit cells to a stable and high DC link voltage for electric vehicle applications.

• Korean journal of applied entomology
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• v.60 no.4
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• pp.463-471
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• 2021

As a tropical plant, the neem tree (Azadirachta indica) has been used for a long time for disease and pest control and medical purposes. In this paper, we reviewed for the active ingredient of neem, the mode of action of azadirachtin in terms of insect growth regulation, repellent, feeding inhibition and oviposition against plant pests. And also we reviewed the current status of practical use in Korea. Among 57 products of neem-based eco-friendly organic agricultural materials distributed in Korea, seven products were certified for their efficacy. The average azadirachtin content of the seven products was 0.38%, which was 5.5 times less than the average content of 2.1% distributed worldwide. In the control effect on neem products in Korea, it showed some variation on aphids, but most showed a control effect of more than 90%. The treatment effects of Lycorma delicatula nymphs were 73-77%, and the control effects for thrips were obtained in the range of 50-72% mortality. The mortality effects against bug and moth species were generally low. It is expected that this review would provide important information necessary for the understanding of distributed neem products and the interpretation of experimental data.

• Journal of Electrical Engineering and Technology
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• v.1 no.1
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• pp.110-113
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• 2006

A high rate deposition sputtering process of magnesium oxide thin film in oxide mode has been developed using a 20 kW unipolar pulsed power supply. The power supply was operated at a maximum constant voltage of 500 V and a constant current of 40 A. The pulse repetition rate and the duty were changed in the ranges of $10\sim50$ kHz and $10\sim60%$, respectively. The deposition rate increased with rising incident power to the target. Maximum incident power to the magnesium target was obtained by the control of frequency, duty and current. The deposition rate of a moving state was 9 nm m/min at the average power of 1.5 kW. This result shows higher deposition rate than any other previous work involving reactive sputtering in oxide mode. The thickness uniformities over the entire substrate area of $982mm{\times}563mm$ were observed at the processing pressure of $2.8\sim9.5$ mTorr. The thickness distribution was improved at lower pressure. This technique is proposed for application to a high through-put sputtering system for plasma display panels.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.93-99
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• 2011

This paper proposes a novel network jitter estimation algorithm for robust VoIP communication system. The proposed method computes the current network environment mode using the differences of arrival time and generation time from sequential received packets. According to the current network environment mode, the jitter variance weights is adjusted to minimize the error for estimating the network jitter. The jitter average and variance are calculated by the autoregressive estimated algorithm, and then the network jitter is estimated by applying the jitter variance weights.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1560-1561
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• 2006

A high rate deposition sputtering process of magnesium oxide thin film in oxide mode has been developed using a 20 kW unipolar pulsed power supply. The power supply was operated at a maximum constant voltage of 500 V and a constant current of 40 A. The pulse repetition rate and the duty were changed in the ranges of $10{\sim}50\;kHz$ and $10{\sim}60%$, respectively. The deposition rate increased with rising incident power to the target. Maximum incident power to the magnesium target was obtained by the control of frequency, duty and current. The deposition rate of a moving state was 9 nm m/min at the average power of 1.5 kW.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.530-533
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• 2001

Interleaved Dual Boost(IDB) converter can reduce current ripple, switching loss and harmonics without filter in input power line. Moreover, this improve power factor. In this paper, we will use the state average methode and small signal analysis at the Interleaved dual boost converter. 4-type controllers were designed by using control transfer function. The result of these controller simulations is analyzed and proposed a proper controller at IDB

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.31-35
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• 2003

This paper presents a microprocessor controlled digital ballast for HID lamps, which gives intelligent features such as a precise power control, optimum ignition voltage and detection of end of life. Average current mode PFC is employed for reducing EMI and a universal input. Direct spread spectrum is done by applying 1 KHz triangular wave for removing acoustic resonance. This frequency modulation of 1 KHz gives also low EMI level and no ripple on lamp current. The microprocessor controls the voltage of DC-bus, the voltage of ignition pulses, the power of output and the bandwidth of spread spectrum. A 250W digital ballast is implemented with an efficiency of 93％ and a maximum EMI level of 55 ㏈${\mu}$V.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.160-163
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• 2004

A passive lossless turn-on/turn-off snubber network is proposed for the boost PWM converter. Previous AC/DC PFC Boost Converter perceives feed forward signal of output for average current-mode control. Previous Boost Convertor, the Quantity of input current will be decreased by the decrease of output current in light load, and also Power factor comes to be decreased. Also the efficiency of converter will be decreased by the decrease of power factor. The proposed converter presents the good PFC, low line current harmonic distortions and tight output voltage regulations using energy recovery circuit. All of the semiconductor devices in the converter are turned on under exact or near zero voltage switching(ZVS). No additional voltage and current stresses on the main switch and main diode occur. To show the superiority of this converter is verified through the experiment with a 640W, 100kHz prototype converter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.560-565
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• 2011

This paper proposes the design of micro energy harvesting system by using thermoplastic polyurethane(TPU), which harvests electric energy from the kinetic energy of pedestrian and drives the desired load, and applied it to the self-generating shoes. Also, we designed the buck-boost converter in discontinuous conduction mode(DCM) which functions as a resistor emulator(RE) such that converter's average input current is proportional to input voltage, and it results in transfer of maximum power to buck-boost converter according to control behavior that converter's input resistance is matched with TPU's internal resistance. Therefore, this paper confirms the validity of proposed control scheme and possibility of application for self-generating shoes, from the obtained characteristic of designed micro energy harvesting system by using a TPU and buck-boost converter in DCM.