• 한국수소및신에너지학회논문집
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• 제34권2호
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• pp.141-148
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• 2023

The thermodynamic performance of the electrochemical hydrogen compressor was analyzed to perform a comparative analysis with the performance of the mechanical compressor. The performance was analyzed through the applied current and the measured voltage value. The test results showed that the efficiency of the electrochemical hydrogen compressor was high in the low current density range. In addition, it was confirmed that the amount of increasing compress work of the electrochemical hydrogen compressor is smaller than that of the mechanical compressor. Therefore, it is expected to have higher efficiency than mechanical compression when compressed with a sufficiently high-pressure range.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.625-630
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• 2005

In this paper, several energy recovery circuits (ERC) for the plasma display panel (PDP) are reviewed and classified in a manner of operation characteristics. A typical ERC using the Regenerative Transformer (RT) is introduced and compared with conventional ones. RT-ERC can achieve zero-voltage-switching (ZVS) for main full-bridge switches and zero-current-switching (ZCS) for the resonant switches and diodes. The charging/discharging energy of panel capacitance is efficiently recovered with the RT and without a sub-circuit. The presented circuit is verified with simulation and experimental results.

• 조명전기설비학회논문지
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• 제27권2호
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• pp.62-68
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• 2013

The dynamic voltage restorer (DVR) is an effective protection device for wind turbine generators based on doubly-fed induction generator (DFIG) that is operated under unbalanced voltage dip conditions. The compensating voltages of the DVR depend on the voltage dips and on the influence of the zero sequence component. The zero sequence component results in high insulation costs and asymmetry in terminal voltages. This paper proposes the use of a proportional-resonant controller in stationary reference frames for controlling zero sequence components in the DVR to protect the DFIG during unbalanced voltage dips. To enhance the proposed control method, a comparison is carried out between two cases: with and without using the control of a zero sequence component. Simulation results are presented to verify the effectiveness of the proposed control method by using the Psim simulation program.

• 물과 미래
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• 제22권4호
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• pp.441-451
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• 1989

한반도 주변해상에 큰 영향을 미친 태풍 LEE, VERA, THELMA 통과시의 파랑관측 자료에 대하여 zero-up & down crossing법 및 Tucker-Draper법으로 구한 유의파고를 파랑스펙트럼법으로 구한 유의파고와 비교분석하였다. 그리고 zero-up crossing법으로 구한 개별파의 파고분포를 Rayleigh, Weibull, Gluhovski, Ibrageemov, Goda의 분포와 비교한 후 Chi-square 검증을 실시하였다. 분석결과 zero-crossing법으로 구한 유의파고가 스펙트럼에서 구한 유의파고와 가장 잘 일치하였으며, 파고분포는 Rayleigh와 Goda 분포가 관측치에 가장 잘 맞는 것으로 나타났다.

• 제어로봇시스템학회논문지
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• 제17권10호
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• pp.1029-1036
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• 2011

An energy-efficient reference walking trajectory generation algorithm is suggested utilizing allowable ZMP (Zero-Moment-Point) region, which maxmizes the energy efficiency for cyclic gaits, based on three-dimensional LIPM (Linear Inverted Pendulum Model) for biped robots. As observed in natural human walking, variable ZMP manipulation is suggested, in which ZMP moves within the allowable region to reduce the joint stress (i.e., rapid acceleration and deceleration of body), and hence to reduce the consumed energy. In addition, opimization of footstep planning is conducted to decide the optimal step-length and body height for a given forward mean velocity to minimize a suitable energy performance - amount of energy required to carry a unit weight a unit distance. In this planning, in order to ensure physically realizable walking trajectory, we also considered geometrical constraints, ZMP stability condition, friction constraint, and yawing moment constraint. Simulations are performed with a 12-DOF 3D biped robot model to verify the effectiveness of the proposed method.

• 한국농촌건축학회논문집
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• 제26권2호
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• pp.1-8
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• 2024

Carbon neutrality refers to a state in which there is no global increase in CO₂ emissions due to human activities. In Korea, for carbon neutrality, green remodeling of existing buildings and customized support tasks for zero energy in new buildings are presented. Germany is showing fundamental changes in energy supply, such as applying renewable energy and higher energy efficiency from nuclear and fossil fuels, which were the existing energy sources. In this study, how Germany establishes policies for carbon neutrality at each state level and the cases applied to increase the energy efficiency of the actually applied residential complexes are analyzed based on this. As a result of the case complex analysis, it was found that the construction direction was being promoted as a zero-energy complex or a carbon-neutral complex by gradually reducing the energy demand in buildings and supplying additional energy with new and renewable energy in the low-energy building distribution in the 1990s. In Germany's ecological complex, energy standards have been strengthened from low-energy architecture to plus-energy architecture over time, and annual heating energy consumption standards and heat transmittance rates for each structure have been achieved at a higher level. The results of this analysis will serve as basic data and derivation of applicable items when planning residential complex development and remodeling of existing buildings for the domestic carbon-neutral goal in the future.

• 지열에너지저널
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• 제5권1호
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• pp.34-39
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• 2009

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권10호
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• pp.501-507
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• 2001

In this paper, new high-efficiency zero voltage switching (ZVS) AC-DC boost converter is proposed to achieve power factor correction by simplifing energy recovery circuit. A lot of high power factor correction circuits have been proposed and applied to increase input power factor and efficiency. Most of these circuits may obtain unity power factor and achieve sinusoidal current waveform with zero voltage or/and zero current switching. However, it is difficult for them to obtain low cost, small size, low weight, and low noise. The topology proposed to improve these problems can compact the devices in circuit and can achieve high efficiency ZVS AC-DC boost converter. Simulation and experimental results show that this topology is capable of obtaining high power factor and increasing the efficiency of the system.

• 전산구조공학
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• 제1권2호
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• pp.83-90
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• 1988

본 연구에서는 평판 구조물의 해석을 위한 개선된 유한요소를 제시하였다. 이 요소는 Mindlin 평판이론에 의하여 수식화되었으며, 'Heterosis'평판요소의 변위장에 비적합변위형을 추가함으로써 유도되었다. 본 연구에서 제시한 평판요소는 요소의 강체운동과 관련된 Zero Eigenvalue만을 갖고 있으므로 Spurious Zero Energy Mode를 보이지 않는다. 대표적인 문제에 대한 수치해석을 해 본 결과 본 연구에서 제시한 평판요소는 우수한 수렴도를 보여 주었으며, 아주 얇은 평판문제에서도 요소의 형상에 관계없이 Shear Locking현상을 극복하였다.

• Journal of Power Electronics
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• 제17권2호
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• pp.422-431
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• 2017

The equivalent circuit of a three-leg, four-wire voltage source converter (VSC) is derived using switching functions. Simulations and experiments are conducted (i) to investigate the effects of the zero sequence on VSCs when a three-phase imbalance exists and (ii) to use the consistency of simulations and laboratory experiments to validate the equivalent circuit. The impact of a three-phase imbalance on the VSC has yet to be fully investigated because of the lack of an equivalent circuit to show rigorously how the zero sequence currents flow through the VSC.