• 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.

• 한국광학회지
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• 제5권1호
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• pp.37-44
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• 1994

유도 브릴루앙 반사광을 고출력 레이저에 응용할 때 요구되는 반사광 특성이 실험적으로 조사되었다. 집속 렌즈의 초점거리에 따른 유도 브릴루앙 반사광의 peak power 반사율과 위상공액도가 측정되었다. 또한 반사광 가운데 펄스압축된 부분만의 위상공액도가 측정되었다. 초점거리가 긴 경우(f=100cm) 반사광의 peak power가 입사광의 약 2배에 이르렀다. 이때 반사광 중에서 압축된 선두펄스만의 위상공액도는 약 90%로 다른 시간의 펄스보다 위상공액도가 우수했다. 공간적으로는 유도 브릴루앙 이득이 가장 큰 광축부분의 바사관이 최대의 펄스압축, peak power 반사율, 위상공액도를 보여서 유도 브릴루앙 산란을 응용할 때 가장 유용한 부분으로 확인되었다.

• 전기학회논문지
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• 제63권1호
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• pp.27-34
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• 2014

The paper proposed a sizing method of an energy storage system(ESS) for peak shaving of high-speed railway substations based on load profile patterns of substations. A lithium based battery ESS was selected since it can produce high-power at high speed that peak shaving requires, and also takes up a relatively smaller space for installation. Adequate size of the ESS, minimum capacity which can technically meet a peak shaving target, was determined by collectively considering load patterns of a target substation, characteristics of the ESS to be installed, and optimal scheduling of the ESS. In case study, a local substation was considered to demonstrate the proposed sizing method. Also economic analysis with the determined size of ESS was performed to calculate electricity cost savings of the peak shaving ESS, and to offer pay-back period and return on investment.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.7-8
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• 2008

It is well-known that one of the most serious problems of Orthogonal Frequency Divison Multiplexing (OFDM) is its high Peak-to-Average Power Ratio (PAPR) which seriously limits the power efficiency of High Power Amplifier (HPA). This paper introduces various methodologies to cope with this problem.

• 조명전기설비학회논문지
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• 제28권9호
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• pp.20-27
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• 2014

The power consumption pattern of high-speed railway has rarely during night time. But, during service time, the power is consumed irregularly related to train operation. Especially certain unusual about 1-2 days of service time interval to indicate the power consumption is rapidly growing phenomenon, which causes the capacity of the power contract is the annual electricity bill to rise rapidly as the cause. Normally, amount of peak power consumption bill rate at railway substation is over 20% of total electrical bill. Therefore, high-speed railway substation is expected to be considerably larger savings by reducing the peak power of the default charge(demand power).

• Physical Therapy Rehabilitation Science
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• 제10권4호
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• pp.457-462
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• 2021

Objective: This study analyzed the correlation between uni-standing balance ability, jumping ability, and anaerobic lower extremity power of high school Taekwondo players. Design: Cross-sectional study Methods: Two high schools recruited 36 taekwondo players, but 5 were dropped due to personal circumstances and preparations for the tournament, so the number was counted as 31. In order to test uni-standing balance ability, the Romberg test was performed using Biorescue to measure the sway area. In order to test jumping ability, standing long jump and standing highjump were measured. For anaerobic lower extremity muscle power test, the peak power and average power were measured through 30-second pedaling using a Wingate system bicycle. Results: Participants did not show any correlation with other measures in the uni-standing balance ability test (p>0.05). Looking at the correlation in the standing long jump, standing high jump (r=0.892, p<0.05), anaerobic peak power (r=0.698, p<0.05), anaerobic average leg power (r=0.662, p<0.05) showed a positive correlation. Looking at the correlations in the standing high jump, anaerobic peak power (r=0.663, p<0.05), anaerobic average power (r=0.697, p<0.05) showed a positive correlation. Looking at the correlation in the anaerobic peak power, average power (r=0.785, p<0.05) showed a positive correlation. Conclusions: This study shows that balance ability and anaerobic leg strength are independent of each other. The results of this study can be used as basic data for the training plan of high school taekwondo players in the future.

• 전기학회논문지
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• 제65권3호
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• pp.404-410
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• 2016

This paper proposed a program of an energy storage system(ESS) for peak shaving of high-speed railway substations The peak shaving saves cost of equipment and demand cost of the substation. To reduce the peak load, it is very important to know when the peak load appears. The past data based load profile forecasting method is easy and applicable to customers which have relatively fixed load profiles. And an optimal scheduling method of the ESS is helpful in reducing the electricity tariff and shaving the peak load efficiently. Based on these techniques, MS. NET based peak shaving program is developed. In case study, a specific daily load profile of the local substation was applied and simulated to verify performance of the proposed program.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1550-1551
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• 2006

An L-band linear accelerator system for e-beam sterilization is under design for bio-technology application. The klystron-modulator system as RF microwave source has an important role as major components to offer the system reliability for long time steady state operation. A PFN line type pulse generator with a peak power of 71.5-MW, $7{\mu}s$, 285 pps is required to drive a high-power klystron. The high power pulse transformer has a function of transferring pulse energy from a pulsed power source to a high power load. The pulse transformer producing a pulse with a peak voltage of 275 kV is required to produce 30-MW peak and 60 kW average RF output power at the frequency of 1.3-GHz. We have designed the high power pulse transformer with 1:13 step-up ratio. The peak and average power capability is 71.5-MW (275 kV, 260 A at load side with $7{\mu}s$ pulse width) and 130 kW, respectively. In this paper, we present a system overview and initial design results of the high power pulse transformer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1079-1081
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• 2007

An L-band Linear Accelerator System for E-beam sterilization is under construction for bio-technology application. The klystron-modulator system as an RF microwave source has an important role as major components to offer the system reliability for long time steady-state operations. A PFN line type pulse generator with a peak power of 71.5-MW, $7\;{\mu}s$, 285 pps is required to drive a high-power klystron. The high power pulse transformer has a function of transferring pulse energy from a pulsed power source to a high power load. The pulse transformer producing a pulse with a peak voltage of 275 kV is required to produce 30-MW peak and 60 kW average RF output power at the frequency of 1.3-GHz. We have designed the high power pulse transformer with 1:13 step-up ratio. The peak and average power capability is 71.5-MW (275 kV, 260 A at load side with $7\;{\mu}s$ pulse width) and 130 kW, respectively. In this paper, we present measurements and its analysis on the design parameters, and an initial test result as well as a design concept on the high-power pulse transformer.

• 전기학회논문지
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• 제63권1호
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• pp.191-196
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• 2014

For the large scale of electricity consumer, since the price for the electricity consumption depends on the peak power, the issue for peak power reduction have been being studied widely. Electric railway systems, which is one of the most representative large scale of loads, also has assignment to reduce the peak power since they have high peak power and low energy consumption load characteristics. In the aspect of the economic operation through reduction of peak power, this paper proposes a novel algorithm for power management system in electric railway systems using energy storage.