• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.251-255
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• 1997

The conventional high frequency phase-shifted full bridge dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of transformer and switching devices are increased. To alleviate this problem, this paper provides a circulating current free type high frequency soft switching phase-shifted full bridge (FB) dc/dc converter with energy recovery snubber (ERS) attached at the secondary side of transformer. The energy recovery snubber (ERS) adopted in this study is consisted of three fast recovery diode(Ds1, DS2, Ds3), two resonant capacitor (Cs1, Cs2)

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.157-158
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• 2011

An active-clamped current-fed half-bridge converter is used for front-end converter for grid-connection of low voltage energy sources. In this paper, theoretical analysis on the loss and efficiency for an active-clamped current-fed half-bridge converter is presented. To analyze the loss of the presented converter, the RMS current of each device is derived and it's loss is calculated. The comparison between simulation result and computed value is presented to verify the validity of the theoretic results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1569-1571
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• 2000

The ageing process was checked by leakage current monitoring in Salt Fog Method. In order to monitor leakage current, DAS with 12-bit, 8-channel A/D converter was prepared. The monitored components of leakage current were averages of the rms and peak, max peak, cumulative charge, and the cumulative number of peak pulses. The acquired data were stored to the disc periodically. And, surface conductivity was measured to investigate loss of hydrophobicity. The results suggest that surface conductivity and leakage current are well corresponding to initial loss of hydrophobicity.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.121-124
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• 2002

The conventional three-level high frequency phase-shifted dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due In this circulating current and RMS current stress, conduction losses of transformer and switching devices increases. To alleviate these problems, we propose an improved three-level Zero Voltage and Zero Current Switching (ZVZCS) dc/dc converter using a tapped inductor, a snubber capacitor and two snubber diodes attached at the secondary side of transformer The proposed ZVZCS converter is verified on a 7kW, 30kHz experimental prototype.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.689-693
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• 2001

The conventional three-level high frequency phase-shifted dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current and RMS current stress, conduction losses of transformer and switching devices increases. To alleviate these problems, we propose an improved three-level Zero Voltage and Zero Current Switching (ZVZCS) dc/dc converter using a tapped inductor, a snubber capacitor and two snubber diodes attached at the secondary side of transformer. The proposed ZVZCS converter is verified on a 10 kW, 30kHz experimental prototype.

• 한국조명전기설비학회지:조명전기설비
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• 제1권1호
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• pp.75-82
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• 1987

종래, 위상제어의 전력전자 회로는 전원에서 고주파분이 많이 포함되고 역율을 저하시키는 원인이 되었다. 그러므로, 본 연구에서는 이러한 영향을 개선시키기 위하여 Optimal PWM 방식을 제시하였다. Optimal PWM 콘버어터는 전원에서 실효 고주파분을 최소화하는 것이며, Optimal PWM 인버어터와 쌍대성이 있음을 알 수 있었다. Optimal PWM 콘버어터의 전류패턴은 Optimal PWM 인버어터의 전압패턴과 같은 스위칭패턴과 제어방법을 얻을 수 있었다. 이러한 PWM방식을 실현하기 위하여 고속 스위칭소자가 필요하게 되었다. 이전에는 강제 전류회로인 싸이리스터가 사용되었으나, 최근에 와서는 전류용 TR 또는 GTO 소자 등을 사용함으로써 이와같은 PWM 특성을 쉽게 실현할 수 있었다. 본 연구에서의 전원에서 실효 고주파 전류를 최소화하기 위한 제어방법, 회로 및 결과를 제시하였다.

• The Journal of Korean Physical Therapy
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• 제18권2호
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• pp.25-34
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• 2006

Purpose: This study conducted quantitative sensory test and nociceptive flexion reflex(NFR) measurement to examine degree of pain depending on polarity of high voltage pulsed current(HVPC) of hyperalgesia site in hyperalgesia rat by local thermal injury. mechanical pain threshold, thermal pain threshold and root mean square of NFR were measured. Methods: This study was conducted with control group I of hyperalgesia rat at hind paw by thermal injury and experimental groups divided into cathodal HVPC group II, anodal HVPC group III and alternate HVPC group IV. It measured pain threshold and root mean square(RMS) of NFR and obtained the following results. Results: Mechanical pain threshold of hyperalgeisa site was significantly increased at groups II, III and IV applying HVPC group compared to control group, but there was no difference among HVPC groups. Thermal pain threshold of hyperalgesia site showed a significant increase in group II. Group III showed significant difference after 4 days of hyperalgesia. RMS of NFR at hyperalgeisa site was significantly reduced in group II after 2 days of hyperalgesia. Group III showed significant decrease after 5 and 6 days of hyperalgesia. Conclusion: Consequently it was found that application of HVPC of hyperalgesia site increased pain threshold at hyperalgesia site by mechanical stimuli and thermal stimuli. NFR by electrical stimuli was similar to pain threshold by mechanical stimuli. Effects by polarity of HVPC showed the greatest reduction of hyperalgesia when cathodal electrode was used.

• 한국환경과학회지
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• 제6권5호
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• pp.541-550
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• 1997

해양의 몇몇 정점에서 관측된 유속자료로부터 속도 유선함수를 최소자승 회귀분석법을 응용하여 산출하였다. 유선함수는 삼각함수의 합으로 표현되며 이들 함수의 상수들은 2차원 유속장의 비발산 부분을 최소화하여 구하였다. 위의 방법은 기존의 방법들이 요구하는 관측치의 보강이 필요치 않으며 관측 및 흐름장의 발산에 기인하는 오차를 계산할 수 있는 장점이 있다. 연안역의 복잡한 해안경계 문제를 쉽게 표현하기 위하여 연안을 경계로 하는 곡선직교좌표를 도입하여 유선함수를 구하였다. 텍사스-루이지아나 대륙붕 순환 및 수송 연구(LATEX)를 위하여 31개 정점에서 관측된 해류계자료를 이용 텍사스-루이지아나 대륙붕상의 속도유선함수를 성공적으로 산출하였다. 위의 해역에서 유선함수 산출오차는 비교적 적게 나타나 유선함수가 표층 유속장을 잘 나타냄을 알 수 있다.

• 한국수산과학회지
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• 제19권3호
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• pp.274-280
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• 1986

대, 소조기에 마산만에서 연속관측한 자료를 사용하여 만구 단면의 유속 변동특성을 구명하기 위하여 net velocity와 RMS속도의 등양선 및 순 유출입량을 계산하여 검토하였다. 최강유속은 수도 중앙과 서부의 4m 이하의 표층에서 나타나고, 최대 유입속도 24cm/sec 최대 유출속도는 15 cm/sec이다. 최강유속 시간임에도 불구하고 4m 이심에서는 유속이 약하여 $0{\sim}2cm/sec$에 불과하다. 만구 단면의 가장자리의 상층에 역류가 존재한다. net velocity는 비가 오지 않은 대조기의 경우 유출유속은 만구단면 서부에서 나타나며, 유입유속은 단면 동부에서 나타난다. 비온 직후의 소조기에는 이와 정반대로 흐른다. RMS속도의 최대 세기는 대조기에 $11.3{\sim}15.0cm/sec$, 소조기에 $7{\sim}10.3cm/sec$로서 단면 서부의 표층에 있으며, 매 조석주기마다 거의 동일위치에서 계속 존재한다. 순 통과유량은 건기에 $-39.7m^3/sec$, 우기 $-170m^3/sec$로서 유출이 탁월하다. 항유성분은 건기에는 조석잔차류가 우세하지만, 소조기의 강우시에는 밀도류가 우세한 것으로 추리된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.104-107
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• 2005

Recently, according to the development of semiconductor industry, needed to high-integration and high-functionality. These changes are required for silicon wafer of large scale diameter and precision of TTV (Total Thickness variation). So, in this research, suggest that the method of monitoring system is using motor current. This method is needed for observation of silicon wafer grinding process. Motor current sensor is consisted of hall sensor. Hall sensor is known to catching of change of current. Received original signal is converted to the diginal, then, it is calculated RMS values, and then, it is analysed in computer. Generally, the change of force is relative to the change of current, So this reason, in this research tried to monitoring of motor current change, and then, it will be applied to analysis for silicon wafer grinding process. using motor current sensor.