• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.859-866
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• 2001

During the Pre-service Inspection for Wolsong Unit 3&4 in 1997/1998 respectively, 17 Distorted Roll Transition indications(over expanded beyond tubesheet secondary face) were identified at the Unit 4 (S/G B, D). Six(6) tubes out of these tubes were plugged in 1998. However the first Periodic Inspection identified additional 110 indications in 1999 and 2000. The additionally identified 110 indication call, not reported at the Pre-service Inspection, are; 2 Not-Finally-Expanded-Tubes and 108 Distorted Roll Transition tubes. Design limit of each Steam Generator tube Plugging is 6.4%. Plugging was performed by the Steam Generator manufacturer under the warranty. When Distorted Roll Transition indications were first identified on the Unit 4 in 1998 the degree of Over-expansion was measured using an inner dial-gage to make the disposition of Nonconformance report. 2 Not-Finally-Expanded-Tubes were plugged and 10 tubes out of 108 Distorted Roll Transition Tubes were also plugged as a preventive measure.

• Journal of the Korean Statistical Society
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• 제36권2호
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• pp.257-274
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• 2007

This paper considers the tests for the presence of smooth transition non-linearity in the partially nonstationary vector autoregressive model. The transition parameters cannot be identified under the null hypothesis of linearity, and therefore this paper develops the tests for smooth transition nonlinearity, the associated asymptotic theory and the bootstrap inference. The Monte Carlo simulation evidence shows that the bootstrap inference generates moderate size and power performances.

• 대한전자공학회논문지SD
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• 제46권5호
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• pp.15-24
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• 2009

본 논문은 유사랜덤 방식의 BIST를 기반으로 하여 스캔 shifting시의 transition을 획기적으로 줄여 주었던 transition freezing 기법과 새롭게 제안하는 고장검출율 100%를 위한 pattern mapping 기법을 결합한 효과적인 저전력 BIST구조에 대해 제안한다. Transition freezing 기법으로 생성된 고연관의 저전력 패턴은 패턴 인가 초기에는 많은 수의 고장을 검출해 내지만, 패턴의 수가 점점 늘어날수록 랜덤 저항 고장의 증가로 인해 추가적인 고장 검출에는 한계가 있었다. 이러한 비검출 고장에 대해 ATPG를 통한 테스트 패턴을 생성하여, 고장을 검출하지 못하는 frozen pattern과 mapping을 함으로써 기 생성된 패턴을 재활용하여 인가되는 패턴의 수와 테스트 시간을 줄임으로써 전력 소모량을 줄일 수 있었다.

• 자원ㆍ환경경제연구
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• 제29권4호
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• pp.443-468
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• 2020

전기차 관련 기술 발달과 보급 확대로 화물, 이륜차 등 일반승용 부문을 넘어 육상수송 전반에 걸친 연료전환 효과가 발생하고 있다. 본 연구는 대도시에서 긴 주행거리를 운행하는 사업용 승용차(택시)의 연료전환에 따라 발생하는 대기환경편익을 택시의 운행특성과 충전전력의 발전원별 비중을 동시에 반영하여 추정하였다. 분석 결과 LPG를 연료로 하는 택시의 연료 전환 효과는 제8차 전력수급기본계획을 기초로 한 발전원별 비중을 고려했을 때 약 21.5원/km로 분석되었으며, 택시 한 대가 출고되어 폐차될 때까지의 전체 운행거리를 기준으로 할 때 약 860만 원 수준으로 추정되었다. 이러한 연구 결과는 최근 국내외에서 활발히 추진되고 있는 재생에너지발전 및 전기자동차 보급 확대 정책의 필요성 및 당위성을 보여준다.

• Journal of Power Electronics
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• 제19권3호
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• pp.691-701
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• 2019

To solve the problems in the contact charging of inspection robots, a wireless charging system for inspection robots and a control strategy are introduced in this paper. Circuit models of a wireless power system with a compound compensation circuit and a three-phase Class-D resonant inverter are set up based on circuit theory. An output voltage control method based on the equal spread regulation of the phase difference between adjacent phases and the parameter correction method in the primary compound compensation circuit are proposed. The dynamic characteristics of the key parameters varying with the secondary coil position are obtained to further investigate the adaptive location scheme during the access and exit processes of moving robots. Combining the output voltage control method and the adaptive location scheme, a transition control strategy for the standby and operation modes of the wireless charging systems for inspection robots is put forward to realize the system characteristics including the low standby power in the standby mode and the high receiving power in the operation mode. Finally, experiments are designed and conducted to verify the correctness of the theoretical research.

• 반도체공학회 논문지
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• 제1권1호
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• pp.14-22
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• 2023

본 논문에서는 dual change-sensing 기법을 사용하여 내부 노드 변환을 최소화시킨 저전력 플립플롭 회로를 제안한다. 제안하는 Dual Change-Sensing Flip-Flop(DCSFF)은 데이터 변환이 존재하지 않는 경우, 기존에 존재하던 플립플롭들 중 동적 전력 소모가 가장 낮다. 65nm CMOS 공정을 사용한 측정 결과에 따르면, conventional Transmission Gate Flip-Flop(TGFF)와 비교하여 data activity 가 0% 와 100% 일때, 각각 98%와 32%의 감소된 전력 소모를 보였다. 또한 Change-Sensing Flip-lop(CSFF)과 비교하여 제안하는 DCSFF 는 30% 의 낮은 전력 소모를 보였다.

• 전기학회논문지P
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• 제57권3호
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• pp.225-230
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• 2008

Reactor starting method has the advantage of simplicity and closed transition in spite of lower starting torque per kVA. This method allows a smooth start with almost no observable disturbance on transition and is suitable for applications such as centrifugal pumps or fans. Reactive power doesn't contribute to work but needs to sustain the electromagnetic field required for the induction motor to operate. Starting power factor of induction motor is specially lower than running power factor. Power factor application is needed to compensate for the lower power factor of induction motor. This power factor compensation systems is occasionally being hit by the effects of the starting reactor connection position at the starting, stopping of high-voltage induction motor. This paper describes voltage and current stress affected by the installation position of power factor compensation application at the reactor starting method.

• 동력기계공학회지
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• 제13권2호
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• pp.30-35
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• 2009

Numerical Calculations for dimensionless pressure drop (friction factor times Reynolds number) have been obtained for fully developed laminar flow of MPL(Modified Power Law) fluid in isosceles triangle pipes. The solutions are valid for Pseudoplastic fluids over a wide range from Newtonian behavior at low shear rates through transition region to power law behavior at higher shear rates. The analysis identified a dimensionless shear rate parameter which for a given set of operating conditions specifies where in the shear rate range a particular system is operating, i.e., Newtonian, transition or power law region. The numerical calculation data of the dimensionless pressure drop for the Newtonian and power law regions are compared with previously published asymptotic results presenting within 0.16 % in Newtonian region and 2.98 % in power law region.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.694-700
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• 1998

A novel zero-voltage-transition (ZVT) isolated PWM boost converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter[8]. A simple auxiliary circuit which includes only one active switch provides zero-voltage-switching (ZVS) condition to all semiconductor devices. (Two active switches are required for the previous ZVT converter) This leads to reduced cost and simplified control circuit comparing to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 kW, 100 KHz laboratory prototype.

• Journal of Power Electronics
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• 제2권4호
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• pp.312-324
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• 2002

This paper presents a new PWM DC/DC converter with dual output power using single power stage, which has the isolation characteristics between each dual output. The proposed converter topology consists of two switches ($S_B$ and $S_F$) and only single secondary winding. Therefore, the proposed converter has better advantages of not only low cost and small size but also high power density because of using minimum components and devices compared with conventional methods which use multi winding transformers or several converters. The operating principle of the proposed converter topology, which includes the conventional auxiliary ZVT (Zero-Voltage-Transition) circuit to implement soft switching of the main switch, is illustrated in detail and the validity of the proposed converter is verified through several simulated and experimental results.