• 전력전자학회논문지
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• 제27권5호
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• pp.376-383
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• 2022

The improved performance of computer parts, such as graphic card, CPU, and main board, has led to the need for power supplies with a high power output. The dynamic load profile rapidly changes the usage of power consumption depending on load operations, such as PC power and air conditioner. Under dynamic load profile conditions, power consumption can be classified into maximum, normal, and standby power. Several problems arise in the case of maximum power. Peak power is generated at the system power source in the maximum-power situation. Frequent generation of peak power can cause high-frequency problems and reduce the life of high-pressure parts (especially high-pressure capacitors). For example, when a plurality of PCs are used, system overload occurs due to peak power generation and causes problems, such as power failure and increase in electricity bills due to exceeded contract power. To solve this problem, a system peak power limit/compensation power circuit is proposed for a power supply under dynamic load profile conditions. The proposed circuit detects the system current to determine the power situation of the load. When the system current is higher than the set level, the circuit recognizes that the system current generates peak power and compensates for the load power through a converter using a super capacitor as the power source. Thus, the peak power of loads with a dynamic load profile is limited and compensated for, and problems, such as high-frequency issues, are solved. In addition, the life of high-pressure parts is increased.

• E2M - 전기 전자와 첨단 소재
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• 제11권10호
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• pp.1-5
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• 1998

Complex dynamic relaxation processes of mechanical as well as dielectric character in polymeric anelastic solids are closely related through the movement of molecular chain segment in morphological structure, and the morphology can easily be modified by the treatments such as mechanical drawing or irradiation, those of which result, in turn, the complicated change on the appearance of the observed complex relaxation peak. In order to extract any meaningful understanding from the modified appearance of the peak, the relaxation peak must be resolved into the sum of the dynamic single relaxation peaks, each of which can be characterized respectively by three factors such as activation energy, magnitude of peak height and peak point temperature on the temperature dependent characteristics.

• Journal of Power Electronics
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• 제10권6호
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• pp.680-685
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• 2010

Although LLC resonant converters have the advantages of a wide operation range and high efficiency, the lack of an analytical solution for the peak gain makes it difficult to optimize the resonant tank design, when considering not only the normal condition but also the holdup time requirement. In this paper, based on a mathematical analysis of a LLC resonant converter at the peak gain point, an analytical solution for the peak gain has been developed. By using the developed analytical solution, the peak gain with given resonant tank parameters can be obtained. To confirm the validity of the developed analytical solution, simulations and experimental results are compared.

• 한국통신학회논문지
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• 제18권7호
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• pp.1036-1043
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• 1993

대기압 MOCVD방법으로 이중 장벽 구조의 공명 투과 소자를 제작하여 상온과 77K에서의 부저항 특성을 특정하였다. GaAs 양자 우물과 spacer, AIGaAs 장벽을 사용하여 성장온도를 변화시켜 공명 투과 소자를 제작한 결과 상온에서 2.35, 77K에서 15.3의 높은 peak-to-valley 전류비를 얻었다 컴퓨터 모의 실험에서는 coherent 투과만을 고려하여 peak 전류를 계산해서 실험치와 잘 일치하는 것을 알 수 있었다. AlGaAs 장벽에 InGaAs 양자 우물과 spacer를 사용하여 전자의 공급량을 증가시킨 구조에서는 상온에서 8.6KA/cm의 높은 peak 전류와 4.0의 큰 peak-to-valley 전류비를 얻었다.

• 대한전기학회논문지:전력기술부문A
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• 제53권2호
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• pp.87-96
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• 2004

This paper summarizes the research results of the load management for pole transformers done in 1997-1998 and 2000-2002. The purpose of the research is to enhance the accuracy of peak load estimation in pole transformers. We concentrated our effort on the acquisition of massive actual load data for modifying the load regression coefficients, which related to the peak load estimation of lamp-use customers, and adjusting the demand-factor coefficients, which used for the peak load prediction of motor-use customers. To enhance the load regression equations, the 264 load data acquisition devices are equipped to the sample pole transformers. For the modification of demand factor coefficients, the peak load currents are measured in each customer and pole transformer for 13 KEPCO (Korea Electric Power Corporation) distribution branch offices. Case studies for 50 sample pole transformers show that the proposed coefficients could reduce estimating error of the peak load for pole transformers, compared with the conventional one.

• 한국분무공학회지
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• 제21권3호
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• pp.155-161
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• 2016

Injected fuel pressure waves of a common rail injector with various current profiles supplied to the injecor were measured using Bosch method. In order to drive the common rail injector, the current in the solenoid should be controlled using what is known as a peak and hold pattern, which consists of a high current level with a short time duration (peak) in the first step and a low current level with a long time duration (hold) in the subsequent step. The current profile can be shaped by swithcing an injector driving power source with the peak and hold waves. The capture, compare and PWM (CCP) pin in the microprocessor was used to generate the combined peak and hold waves. The PWM square wave generated from the CCP pin has a duty ratio of 100% for the peak current and 10% or 30% for the hold pattern. Five patterns of the current profile were generated by combining the peak and hold wave. The common rail pressure is controlled at 75, 100, and 130 MPa. As the fuel rail pressure increases, the variations of the measured fuel injection pressure wave according to the current profiles decrease.

• 한국환경과학회지
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• 제11권10호
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• pp.1081-1087
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• 2002

This study was performed to research the characteristics of suspended particulate for Yellow Sand of January, 1999 in Busan. Yellow Sand frequency during 13 years(1988~2000) in Busan showed maximum in April(57%), next to March(21%), May(16%). According to result of 850hPa weather map and backward isentropic trajectory, this event originated from the Gobi Desert and the Loess Plateau of China. And three mode was found in time series of TSP and PM10 concentration, primary peak showed the maximum hourly concentration at ali station. Gamjeondong as industrial site showed the highest TSP concentration and also had the longest high concentration($geq700\mu\textrm{g}/m^3$). In PM10, concentration of primary peak showed maximum value at Yeonsandong, maximum concentration of secondary and third peak was Deokcheondong. Lasted time from primary peak to secondary peak was about 30 hours, between secondary peak and third peak was 18 hours in Busan, The traveling time between occurrence of Yellow Sand the finding of it was 8~9 hours in Busan and 4~5 hours in central area.

• 전력전자학회논문지
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• 제14권5호
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• pp.415-422
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• 2009

본 논문은 기존의 시스템에 비해 시스템의 전력회로 구조의 큰 변경 없이 밧데리와 같은 전력저장 장치 디바이스의 추가와 개선된 운용방법을 적용한 첨두부하 삭감효과를 갖는 계통연계형 태양광발전시스템(UIPV)을 제안하였다. 개선된 운용방법과 에너지 저장장치의 추가로 기존 시스템에 비해 PV-array 용량을 작게 설치하여도 첨두부하 삭감효과를 크게 할 수 있으며, 가격 및 설치공간 등의 면에서 평가하여 기존시스템보다 더 나아짐을 확인하였다.

• International Journal of Concrete Structures and Materials
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• 제9권1호
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• pp.55-60
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• 2015

In this study, influence of different stone powders (SP), including limestone powders (LP), quartzite powders (QP), and granitic powders (GP), on the hydration behaviors of portland cement, for example, setting time, hydration heat, and hydration products, were discussed. The initial and the final setting time both shorten when the content of LP is 5 %, however, they are slightly delayed by the other two SPs. The LP has no obvious influence on the arrival time of the first peak in the exothermal curves, and it makes the peak value decrease; the other two SPs postpone the appearance of the first peak, and they also make the peak value decrease. For the second peak, LP shifts the peak position to the left, QP has no effect on this peak position, and GP makes the appearance of this peak delayed by 143 min. Similarly, three kinds of SPs have different influence on the hydration products of portland cement. The LP precipitates the formation of hydrated calcium carbo aluminate, the QP the formation of hydrated garnet, and the GP makes the amount of Tobermorite increase.

• 대한교통학회지
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• 제19권4호
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• pp.97-108
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• 2001

기존의 동적 통행배정모형은 출발시간 선택에 있어서 도착시간제약을 고려하지 못하고 있으며, 이를 고려하더라도 수단분담을 고려하지 못하거나 별도의 문제로 다루고 있다. 따라서 대중교통의 수단분담비가 높고, 도착시간에 대한 제약이 따르는 출근·통학통행이 주류를 이루는 오전첨두시의 교통관리·분석을 위해서는 이들을 동시에 고려하는 동적 통행배정모형이 요구된다. 본 연구에서는 Ran과 Boyce가 구축한 모형에 기반하여 통행수단과 도착시간 제약에 따른 출발시간 선택을 경로선택과 동시에 고려할 수 있는 통합모형을 제시하였다. 모형의 풀이를 위해 Ran과 Boyce가 사용한 시·공간 확장 가로망을 새롭게 설계하여 사용하였으며, 가상 가로망에 적용하여 모형의 적합성을 검증하였다. 사례연구 결과 본 연구에서 제시한 모형이 동적 사용자최적 통행배점상태를 나타내는 것을 확인할 수 있었고, 이를 통해 오전 첨두시의 교통관리·분석을 위해 적용 가능함을 입증하였다.