• 한국태양에너지학회 논문집
• /
• 제25권1호
• /
• pp.27-34
• /
• 2005

This study aims to evaluate application of a heat recovery ventilator(HRV) using photovoltaic(PV) system. To this end, we analyzed performance of a PV system, which it was evaluated by monthly power wattage and conversion efficiency according to design capacity of a HRV. The results of this study can be summarized as follows. (1) A conversion efficiency of the PCS was evaluated about 86% in rated power. (2) A maximum, minimum and average output power were respectively analyzed 49.2W, 47.3W, and 48.8W. (3) Total power wattage of 200W PV system was 211kW and it was 316kW in case of 300W PV system. (4) Insufficient electrical power of a duct and window type ventilation system was respectively calculated 133.5kW and 147.7kW.

• Journal of Oral Medicine and Pain
• /
• 제20권2호
• /
• pp.269-281
• /
• 1995

To study the characteristics of EMG power spectrum of masticatory muscles during sustained isometric contraction and recovery at various contraction times, the author analysed the EMG signals of anterior temporal and masseter muscles before, during, and after sustained isometric contraction at 50% level of maximum voluntary contraction (MVC) for 15,30,60 seconds. Twelve normal subjects were included in this study. The author came to following conclusions from the results. 1. MMF of anterior temporal muscle in the contraction period was significantly higher than that of masseter muscle during sustained isometric contraction regardless of isometric contraction times (p<0.05). 2. MMF in the contraction period decreased as the contraction time increased during sustained isometric contraction in both temporal and masseter muscles(p<0.05). 3. SMF in the contraction period increased as the contraction tie increased during sustained isometric contraction in both temporal and masseter muscles(p<0.01). 4. MMF in the first part of recovery period (20 seconds) decreased as the contraction time increased during sustained isometric contraction(p<0.05). However, MMF in the later parts of recovery period (20-120 seconds) showed no significant differences. 5. MMF of anterior temporl muscle in the recovery period was significantly higher than that of masseter muscle after sustained isometric contraction regardless of isometric contraction times (p<0.05). 6. The recovery rate of MF reached 100% in 100 seconds after the isometric contraction regardless of isometric contraction times.

• Journal of Electrical Engineering and Technology
• /
• 제8권4호
• /
• pp.911-919
• /
• 2013

This paper reports the development of test bed with the energy recovering technique using two-step boost converter. The device is utilized for LDC aging test of Hyundai Motor's LPI AVANTE HEV in mass production. The developed power recycle type test bed is designed as 1.5 kW class to test up to the maximum load power of LDC and is also designed to supply scant power supply up to 500 W after power recycle. The theoretical design analysis and operational characteristics analysis results of test bed are reported, and its practicality and reliability are verified through the test result. Also, the finally developed test bed confirms approximately 79~85 % energy saving effect compared to the usual traditional aging test system.

• 한국통신학회논문지
• /
• 제34권2B호
• /
• pp.151-161
• /
• 2009

PULSE 프로토콜은 센서 노드의 슬립을 통해 소모 전력량을 크게 줄인다. 그러나 이 프로토콜은 싱크 노드의 이동을 고려하지 않는 문제가 있다. 모바일 싱크 노드를 가진 센서 네트워크를 위한 라우팅 프로토콜은 빠른 경로 복구와 전력 소모 최소화를 모두 달성해야 한다. 본 논문은 두 목적을 달성하기 위해 모바일 PULSE 프로토콜을 제안한다. 또한, 실험을 통해 제안한 프로토콜의 경로 복구 능력과 전력 소모량을 확인하였다. 이 프로토콜은 기존의 PULSE 프로토콜에 비해 약 40% 정도 경로 복구 시간을 단축하였고, 드롭되는 패킷의 양도 약 1/2 수준으로 줄였다. 전력 소모량 면에서는 최대 0.8%의 증가만이 나타남으로써, 기존의 PULSE 프로토콜의 전력 효율적인 특징을 그대로 유지함을 보였다. 본 논문은 모바일 PULSE 프로토콜의 경로 복구 능력과 전력 소모량을 확인함으로써 모바일 센서 네트워크에 적합한 프로토콜로서의 가능성을 보여준다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제13권3호
• /
• pp.10-13
• /
• 2011

The power demand is steadily increasing due to rapidly develop of industrial field. The ratio of prospected increment of power consumption is over 2.2 % per year from 2007 to 2020 year. The superconducting fault current limiters(SFCLs) should be suggested to be one of promising machines to protect power grid. Four basis tests such as resistivity, short-circuit tests, ac losses and recovery time were investigated according to various reached maximum temperature, operating temperature. This paper deals with investigation of the various commercial high temperature superconductor for applying resistive type SFCLs.

• 전력전자학회논문지
• /
• 제18권5호
• /
• pp.485-491
• /
• 2013

A new passive lossless snubber for boost converter based on magnetic coupling is proposed. It is composed of a winding coupled with boost inductor, one snubber inductor, two snubber capacitor and three additional diodes. Especially, the snubber inductor can not only limit the reverse recovery current of output diode but also minimize switch turn-on losses greatly. Moreover, all of the energy stored in the snubber is transferred to the load in the manner of resonance. To confirm the validity of proposed system, theoretical analysis, design consideration, and verification of experimental results are presented.

• 전력전자학회논문지
• /
• 제19권1호
• /
• pp.23-30
• /
• 2014

This paper proposes a single power-conversion ac-dc converter with a dc-link capacitor-less and high power factor. The proposed converter is derived by integrating a full-bridge diode rectifier and a series-resonant active-clamp dc-dc converter. To obtain a high power factor without a power factor correction circuit, this paper proposes a suitable control algorithm for the proposed converter. The proposed converter provides single power-conversion by using the proposed control algorithm for both power factor correction and output control. Also, the active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. Moreover, it provides zero-voltage turn-on switching of the switches. Also, a series-resonant circuit of the output-voltage doubler removes the reverse-recovery problem of the output diodes. The proposed converter provides maximum power factor of 0.995 and maximum efficiency of 95.1% at the full-load. The operation principle of the converter is analyzed and verified. Experimental results for a 400W ac-dc converter at a constant switching frequency of 50kHz are obtained to show the performance of the proposed converter.

• Journal of Power Electronics
• /
• 제15권1호
• /
• pp.86-95
• /
• 2015

An active clamp high step-up boost converter with a coupled inductor is proposed in this paper. In the proposed strategy, a coupled inductor is adopted to achieve a high voltage gain. The clamp circuit is included to achieve the zero-voltage-switching (ZVS) condition for both the main and clamp switches. A rectifier composed of a capacitor and a diode is added to reduce the voltage stress of the output rectifier diode. As a result, diodes with a low reverse-recovery time and forward voltage-drop can be utilized. Since the voltage stresses of the main and clamp switches are far below the output voltage, low-voltage-rated MOSFETs can be adopted to reduce conduction losses. Moreover, the reverse-recovery losses of the diodes are reduced due to the inherent leakage inductance of the coupled inductor. Therefore, high efficiency can be expected. Firstly, the derivation of the proposed converter is given and the operation analysis is described. Then, a steady-state performance analysis of the proposed converter is analyzed in detail. Finally, a 250 W prototype is built to verify the analysis. The measured maximum efficiency of the prototype is 95%.

• 한국태양에너지학회 논문집
• /
• 제31권6호
• /
• pp.23-31
• /
• 2011

The wind energy is one of the most prospective resources in renewable energy. However, the WTGS shouldn't be installed indiscriminately because the power system can be negatively influenced by a variable and uncertain nature of the wind energy. It is the reason why it has to be limited to install the WTGS thoughtlessly mentioned above that support the importance of the maximum penetration limit of wind power. It may required that power system operators suggests a new way of power system operation as percentage of the WTGS increase in the existing power system. The wind power is fixed in a limited area, so using rate of the wind power will be increased by installing additional WTGS. In this paper, we have studied on economic evaluation of the wind capacity increased by restricting the output of the WTGS as the way to increase the wind capacity.

• 대한기계학회논문집B
• /
• 제34권4호
• /
• pp.383-390
• /
• 2010

본 연구에서는 폐열 회수를 위한 열전 발전 시스템을 구성하였다. 열전 모듈은 스테인레스 스틸덕트 내부에 부착되고, 뜨거운 공기를 불어넣는 장치가 덕트의 입구에 마주한 형태를 취하였다. 이 때 고온부의 온도가 균일한 상태에서 낼 수 있는 최대 파워를 구해내었다. 결과적으로 모듈에 가해지는 최적화된 압력이 있었다. 또한 열전 발전의 성능을 열전 모듈의 저온부의 열 싱크에 의하여 결정되었다. 자연대류 형식의 열 싱크에서 낼 수 있는 파워가 5배 가량 차이가 났다.