• 전자공학회논문지SC
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• 제40권6호
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• pp.16-23
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• 2003

본 논문에서 보청기를 위한 개별 BJT 소자의 효과적인 바이어스 회로를 제안한다. 보청기에 널리 사용되는 컬렉터 귀환 바이어스 회로는 부귀환 저항을 가지고 있다. 이 저항은 AC와 DC에 동시에 영향을 줌으로서 DC 바이어스 점의 변화 없이 증폭기의 이득을 변화시키기 어렵다. 또한 기존회로는 보청기의 이득이 높을 경우 전원 잡음의 정귀환으로 발진할 수 있는 단점이 있다. 제안된 회로는 컬렉터 귀환 바이어스회로에 베이스와 전원 사이에 컬렉터 저항보다 β배 더 큰 저항을 추가하여 기존회로의 두 가지 단점을 줄일 수 있다. 제안된 회로에서 DC 바이어스 점의 변화 없이 증폭기의 이득을 변경 할 수 있고 모의실험에서 기존회로보다 전원 잡음 이득을 18.5%정도 감소시킬 수 있다.

• 한국전기전자재료학회논문지
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• 제25권1호
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• pp.53-57
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• 2012

In this paper, by designing 20 W class driving circuit for driving high-power LED (Light Emitting Diode), we are going to comparatively carry out the analysis of characteristics for power circuit according to each design method. In this case, 200 V 60 Hz was performed as input data. The electrical characteristics such as voltage, current and ripple are checked for constant current circuit and constant voltage circuit in the LED module. In addition, as the ripple has an influence on illumination of LED light, low temperature working (-20 [$^{\circ}C$]) and high temperature working(80 [$^{\circ}C$]) are measured to make sure the ripple characteristics in accordance with temperature. In low temperature operation -20 [$^{\circ}C$] measurements, both constant current circuit and constant-voltage circuit were less impacted on input fluctuation, whereas in the high temperature operation 80 [$^{\circ}C$], current voltage in constant voltage circuit was surge after 430 [hour]. Voltage current ripple of constant current circuit was much less than constant voltage circuit, therefore we can show that constant current circuit is more stable.

• 한국정보통신학회논문지
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• 제13권6호
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• pp.1117-1122
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• 2009

본 논문에서는 온도 센서 및 온도 측정을 위한 제어회로를 설계하였다. 설계된 회로는 기존의 방법들과는 달리 일반적인 CMOS(Complementary Metal Oxide Semiconductor) 공정에서 추가 공정없이 제작 가능하도록 설계하였으며, 온도는 디지털 값으로 출력 되도록 구성하였다. 설계되어진 회로는 5volts 공급전압을 사용하였으며, 0.5${\mu}m$ CMOS 공정을 사용하였다. 온도 측정을 위한 회로는 PWM(Pulse Width Modulation) 제어회로, VCO(Voltage controlled oscillator), 카운터 그리고 레지스터로 구성되어 있다. PWM 제어회로의 동작 주파수는 23kHz 이며, VCO의 동작 주파수는 416kHz, 1MHz, 2MHz를 사용하였다. 회로의 동작은 SPICE(Simulation Program with Integrated Circuit Emphasis)를 사용하여 확인 하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권11호
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• pp.540-546
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• 2005

This paper presents a boost circuit topology driving in high - frequency It solves the problem which arised from hard-switching in high-frequency using a period of resonant circuit and operating under the principle of ZCS turn-on and ZCZVS turn-off commutation schemes. In the existing circuit, it has the high voltage and current stress in free- wheeling diode. But in the proposed circuit, it has voltage and current stress which is lower than voltage and current stress of existing circuit with modifing a location of free-wheeling diode. In this paper, it explained the circuit operation of each mode and the waveform of each mode. Also the experiment results compare the voltage and current stress of free-wheeling diode in the existing circuit with the voltage and current stress of that in the proposed circuit. Moreover, it compares and analyzes the proposed circuit's efficiency with the existing circuit's efficiency according to the change of load current.

• 대한방사선기술학회지:방사선기술과학
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• 제35권4호
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• pp.315-319
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• 2012

본 연구는 위치 민감형 광 증폭 다이오드로부터 나오는 신호를 증폭 및 파형 변화 후 신호의 크기를 검출하여 일정시간 동안 유지시키는 뒷단 회로 개발에 관한 연구이다. 신호발생기에서 발생한 소신호를 증폭 소자를 통한 안정적인 증폭 후 미분회로를 통하여 신호 파형을 검출하기 수월한 형태로 변형 하고, peak/hold 회로에서 피크의 최대점을 일정시간 유지하여 신호의 수집을 원활하게 하였다. 본 회로에 대한 독립적인 성능 평가를 위하여 상용 장비로부터의 검사신호를 입력으로 사용하였다.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.875-880
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• 2018

This paper proposes a novel combined compensation structure in the infrared receiver chip. For the infrared communication chip, the current-voltage (I-V) convert circuit is crucial and important. The circuit is composed by the transimpedance amplifier (TIA) and the combined compensation structures. The TIA converts the incited photons into photocurrent. In order to amplify the photocurrent and avoid the saturation, the TIA uses the combined compensation circuit. This novel compensation structure has the low frequency compensation and high frequency compensation circuit. The low frequency compensation circuit rejects the low frequency photocurrent in the ambient light preventing the saturation. The high frequency compensation circuit raises the high frequency input impedance preserving the sensitivity to the signal of interest. This circuit was implemented in a $0.6{\mu}m$ BiCMOS process. Simulation of the proposed circuit is carried out in the Cadence software, with the 3V power supply, it achieves a low frequency photocurrent rejection and the gain keeps 109dB ranging from 10nA to $300{\mu}A$. The test result fits the simulation and all the results exploit the validity of the circuit.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.138-139
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• 2017

This paper describes the design and implementation of a trigger circuit which can be series connected with main pulse circuit for a xenon flash lamp driver. For generating high voltage, the trigger circuit is designed as an inductive energy storage pulsed power modulator with 2 state step-up circuit consisting of a boost converter and a flyback circuit. In order to guarantee pulse width, a resonant capacitor on the output side of the flyback circuit is designed. This capacitor limits the output voltage to protect the flyback switch. In addition, to protect another power supply of xenon flash lamp driver from trigger pulse, the high voltage transformer which can carry the full current of main pulse is designed. To verify the proposed design, the trigger circuit is developed with the specification of maximum 23 kV, 0.6 J/pulse output and tested with a xenon flash lamp driver consisting of a main pulse circuit and a simmer circuit.

• Journal of Welding and Joining
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• 제23권5호
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• pp.14-19
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• 2005

In high speed $CO_2$ welding, it has been blown to produce no sound bead with undercut or humping bead. In this study welding phenomena through synchronized high speed camera and output welding voltage and current waveform has been analyzed. For the purpose to improve a welding bead, effect of short circuit current rise slope has been examined. With commercial power source it was produced no sound bead by instantaneous short circuit, long arc period and stubbing at welding speed 2.5mm/min Humping bead or undercut were showed by instantaneous short circuit and long arc period. Also, the weld bead was not formed during the long short circuit period after stubbing start and long arc extinguishment period after wire sticking by failure of arc regeneration, because the droplet was not transferred to weld pool. With increasing short circuit current rise slope the frequency of stubbing was decreased and the normal short circuit rate was increased. A control of short circuit current rise slope was effective factor in high speed welding.

• Journal of Welding and Joining
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• 제16권3호
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• pp.95-101
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• 1998

Waveforms of $CO_2$ gas shielded arc welding in short circuit transfer mode was studied with the waveform analysis program, which can calculate various waveform factors such as number of short circuit event, mean and standard deviation of short circuit time and arc time. The calculated values of these factors were correlated independently or in combination with the spatter generation rate to figure out the most reliable index for evaluating spatter generation and further for arc stability. As a result this study, it was confirmed that the spatter generation tends to decrease with the increase of short circuit frequency. Further to this, it was also found that as the short circuit frequency increases the short circuit event becomes more uniform resulting in the decrease of standard deviations ($\sigma$values) of short circuit time and arc time. This result demonstrated that these factors are strongly correlated with each other and thus any one of these factors can be used for the evaluation index. In the discussion, however, short circuit frequency was proposed for the most practical index in evaluating the arc stability of short circuit transfer mode since it is the one which could be monitored in-process condition without any complex caculation process.

• 전력전자학회논문지
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• 제26권3호
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• pp.176-182
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• 2021

This research proposes a high-frequency circuit that can accurately predict the differential mode noise of single-phase inverters at the circuit design stage. Proposed single-phase inverter high frequency circuit in the work is a form in which harmonic impedance components are added to the basic single-phase inverter circuit configuration. For accurate noise prediction, parasitic components present in each part of the differential noise path were extracted. Impedance was extracted using a network analyzer and Q3D in the measurement range of 150 kHz to 30 MHz. A high-frequency circuit model was completed by applying the measured values. Simulations and experiments were conducted to confirm the validity of the high-frequency circuit. As a result, we were able to predict the resonance point of the differential mode voltage extracted as an experimental value with a high-frequency circuit model within an approximately 10% error. Through this outcome, we could verify that differential mode noise can be accurately predicted using the proposed model of the high-frequency circuit without a separate test bench for noise measurement.