• Journal of Power Electronics
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• 제16권6호
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• pp.2221-2230
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• 2016

Voltage and frequency stability issues occur in existing centralized power system due to the high penetration of renewable energy sources, which decrease grid absorptive capacity of them. The grid-connected inverter that mimics synchronous generator characteristics with inertia characteristic is beneficial to electric power system stability. This paper proposed a novel three-phase four-wire grid-connected inverter with an independent neutral line module that mimics synchronous generators. A mathematical model of the synchronous generator and operation principles of the synchronverter are introduced. The main circuit and control parameters design procedures are also provided in detail. A 10 kW prototype is built and tested for further verification. The primary frequency modulation and primary voltage regulation characteristics of the synchronous generator are emulated and automatically adjusted by the proposed circuit, which helps to supports the grid.

• Journal of Power Electronics
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• 제11권3호
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• pp.271-278
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• 2011

This paper presents a LLC resonant controller IC for secondary side control without external active devices to achieve low profile and low cost LED back light units. A gate driving transformer is adopted to isolate the primary side and the secondary side instead of an opto-coupler. A new integrated dimming circuitry is proposed to improve the dynamic current control characteristic and the current density of a LED for the brightness modulation of a large screen LCD. A dual-slope clock generator is proposed to overcome the frequency error due to the under shoot in conventional approaches. This chip is fabricated using 0.35 ${\mu}m$ BCD technology and the die size is $2{\times}2\;mm^2$. The frequency range of the clock generator is from 50 kHz to 500 kHz and the range of the dead time is from 50 ns to 2.2 ${\mu}s$. The efficiency of the LED driving circuit is 97 % and the current consumption is 40 mA for a 100 kHz operation frequency from a 15 V supply voltage.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.319-319
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• 2000

In this paper, A dead-time compensator (DTC) for the processes with long dead-time is proposed. The processes which consist of dead-time, time-constant, gain are estimated by the linear least squares method in the frequency domain. A Smith predictor(SP) modified by including a filter becomes a two degree of freedom DTC. So the proposed DTC can yield the desirable setpoint and load disturbance responses separately. PI controller is used for the primary controller and the filter is tuned to be robust. Simulation examples demonstrate the properties of the proposed DTC.

• 상하수도학회지
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• 제9권3호
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• pp.78-87
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• 1995

A study on the fouling control by periodical ozone-scrubbing was conducted in a membrane filtration process for drinking water treatment. Hydrophilic hollow fiber polyethylene membrane with pore size of $0.1{\mu}m$ and its surface area of $0.42m^2$ was used. Dead-End filtration method was selected to obtain high efficiency of energy. Laboratory prepared synthetic raw water with kaolin was used and the membranes were scrubbed by ozone once in an hour and once in two hours. When the duration of ozone scrubbing was increased from 10 seconds to 20 seconds, the rate of membrane fouling was significantly decreased. Although the frequency of ozone-scrubbing was reduced from once in an hour to once in two hours. the effect of fouling control was unchanged. However, ozone-scrubbing was not effective after a membrane was fouled and washed with detergent for reuse. Among several possible working effects of ozone, bactericidal effect was confirmed to be the primary reason of fouling control.

• 소음진동
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• 제7권2호
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• pp.301-310
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• 1997

This paper presents active noise control method to form the near-field quiet zone for passengers in an automobile. The actuator model including interior acoustic plant, speaker and amplifier is experimentally identified in forms of auto-regressive and moving average by means of least mean square algorithm, The digital controller is composed of the regulator and Kalman filter to be designed based on LQG (linear quadratic gaussian). If the actuator model is prefiltered with digital filter to be properly designed for concentrating control performance index on the frequency band of primary noise source, LQG design approach can be effectively applied for the design of headset controller. Experimental results demonstrate that near-field quiet zone showing about 10dB noise reduction at microphone position can be formed using the headset located at passenger seat.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.23-29
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• 1995

In this study, Active noise controlis implemented with single channel and multi-channel adaptive algorithm in 3 dimensional reverberant enclosure sound. field, which occurrs in complicated acoustic mode. First, for the one case excited with the resonant frequency of an enclosure, a target of control and the other cases excited with band-pass filtered random noise(100~400Hz), it is implemented to control reducing interior noise of enclosure with single channel and realtime multi-channel adaptive algorithm for global noise reduction in enclosure.

• Journal of Acupuncture Research
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• 제25권3호
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• pp.179-187
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• 2008

Objectives & Methods : This study was to investigate effect of low frequency electroacupuncture on NADPH-d positive neurons in the brain cortex of rat with adjuvant induced rheumatoid arthritis. Experimental groups were divided into 6 groups ; Normal, Control, $ST_{36}$, $SP_9$, $ST_{36}+SP_9$ and Non-Acupoint. Normal group, non-arthritic group, was injected normal saline, and the other groups were injected FCA. Each acupoint groups were treated by 2Hz electroacupuncture at each acupoints and NA group was treated by 2Hz electroacupuncture at non-acupoint. Each groups were evaluated by the number of NADPH-d positive neurons in primary somatosensory area(S1), secondary somatosensory area(S2), motor area and caudate putamen by using an image analyzer and a microscope. Results : 1. In S1, the number of NADPH-d positive neuron cells in the $ST_{36}$ group were significantly(p<0.05) increased compared with the control group. 2. In S2, the number of NADPH-d positive neuron cells in all electroacupuncture groups were not significantly changed compared with the control group. 3. In motor area, the number of NADPH-d positive neuron cells in $ST_{36}$ group, $SP_9$ group, NA group were significantly(p<0.05) increased compared with the control group. 4. In Caudate putamen, the number NADPH-d positive neuron cells in all electroacupuncture groups were significantly(p<0.05) decreased compared with the control group. Conclusions : Our result demonstrated that low frequency electroacupuncture on $ST_{36}$ & $SP_9$ normalized expression of NADPH-d positive neurons in the brain cortex of the rheumatoid arthritis model in rats.

• Radiation Oncology Journal
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• 제2권1호
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• pp.123-128
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• 1984

To determine the effectiveness of radiotherapy for pain control in metastatic bone disease, we retrospectively analyzed the treatment results in 126 patients who received short-course radiotherapr(2,000 rad/1wk vs 3,000 rad/2wks) in the Department of Therapeutic Radiology, Seoul National University Hospital from Feb. 1979 to July 1983. Pain relief was obtained in $82\%$ of patients and complete Pain relief was obtained in $35.3\%$ of patients. The incidence of metastatic bone tumor was highest in spine and pelvis, $43.7\%\;and\;26.3\%$>, respectively. Primary sites of metastasia were lung, breast, unknown primary, stomach, uterine cervix, in order of frequency. There was no significant difference in the response to treatment between 2,000 rad in 1 week and 3,000 rad in 2 weeks.

• 한국임상수의학회지
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• 제20권4호
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• pp.516-518
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• 2003

Six year-old female shihtzu was presented as primary epileptic seizure. We had been treated with high dose phenobarbital sodium (6.5 mg/kg), but could not achieved adequate control seizures. In an add-on therapy, the dog was given potassium bromide at a dose of 20 to 40 mg/kg daily for a period of 24 months. This dog has showed a greater than 50% reduction in seizure frequency. The therapeutic range of serum concentration of potassium bromide was from 0.7 to 1.3 mg/ml at 6weeks after treatment. To begin an add-on therapy with potassium bromide it can be recommended at a daily dose of 20 to 40 mg/kg.

• Journal of Power Electronics
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• 제16권6호
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• pp.2359-2367
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• 2016

Inductive power transfer (IPT) systems have become increasingly popular in recharging electric vehicle (EV) batteries. This paper presents an investigation of a series parallel/series (SP/S) resonant compensation network based IPT system for EVs with further optimized circular pads (CPs). After the further optimization, the magnetic coupling coefficient and power transfer capacity of the CPs are significantly improved. In this system, based on a series compensation network on the secondary side, the constant output voltage, utilizing a simple yet effective control method (fixed-frequency control), is realized for the receiving terminal at a settled relative position under different load conditions. In addition, with a SP compensation network on the primary side, zero voltage switching (ZVS) of the inverter is universally achieved. Simulations and experiments have been implemented to validate the favorable applicability of the modified optimization of CPs and the proposed SP/S IPT system.