• Journal of Energy Engineering
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• v.18 no.1
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• pp.37-48
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• 2009

Recently, the significance of Green-Energy led by low-carbon Green-Development is increasing as well in Korea. Among them, the most practical solution is the cogeneration which performs the best energy efficiency. This paper addresses the two of RCS(Regional Cogeneration System) connecting heat each other. It is conducted to quantitatively evaluate algorithm that optimally operate the heat transaction considering various operating modes. The proposed method is tested using the real system. Through the case studies, it is verified that the proposed algorithm of heat transaction can evaluate availability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.953-959
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• 2012

There are a number of idle nodes in sensor networks, these can act as detector nodes for anomaly detection in the network. For detecting node selection problem modeled as optimization equation, the conventional method using centralized genetic algorithm was evaluated. In this paper, a method to improve the convergence of the optimal value, while improving energy efficiency as a method of considering the characteristics of the network topology using parallel genetic algorithm is proposed. Through simulation, the proposed method compared with the conventional approaches to the convergence of the optimal value was improved and was found to be energy efficient.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.6
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• pp.49-53
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• 2002

This paper provides the systematic procedure to determine the weighting matrices of optimal controllers considering structural energy. Optimal controllers consist of LQR and ILQR. The weighting matrices are needed first in the conventional optimal control design strategy. However, they are in general dependent on the experienced knowledge of control designers. Applying the Lyapunov function to total structural energy and using the condition that its derivative is negative, we can determine the weighting matrices without difficulty. It is proven that the control efficiency with using determined weighting matrices is achieved well for LQR and ILQR controllers.

• Environmental and Resource Economics Review
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• v.20 no.2
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• pp.335-356
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• 2011

In this paper, we attempted to suggest a way to evaluate appropriateness and efficiency for the energy consumption structure. For this, based on Markowitz (1952)' mean-variance portfolio model, we constructed an optimal fossil fuel mix. In constructing the optimal mix, we first defined returns on fossil fuels (oil, coal and natural gas) as TOE (Ton of Oil Equivalent) per $1. Then, by using the dynamic latent common factor model, we decomposed the growth rates of the returns on each fossil fuel into two parts : the common part and the idiosyncratic part. Finally, based on the results from the dynamic latent common factor model, we constructed the optimal fossil fuel mix implied by the mean-variance portfolio model. Our results indicate that for the fossil fuel mix to be on the efficient frontier, it is crucial to reduce oil consumption as low as possible. Moreover, our results imply that it is more efficient to increase natural gas consumption rather than coal consumption in reducing oil consumption. These results are in line with the strategies for the future energy consumption structure pursued by Korea and indicate that reduction in oil use can improve overall efficiency in energy consumption.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.133-135
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• 2020

배터리의 가용 영역에 따른 효율적인 운영 방법을 판단하기 위해 방전 깊이(Depth of Discharge; DOD)에 따라 배터리의 노화 상태 및 에너지를 계산하여 최적의 가용 영역을 판단한다. 배터리의 상태를 판단하기 위한 지표로써 건강 상태(State of Discharge; DOD)와 출력 상태(State of Power; SOP)의 분석을 통해 비교한다. 노화 파라미터 및 DOD에 따른 노화 차이를 반영한 알고리즘 구현 및 배터리팩과 시스템 레벨의 효율적인 운영 방안에 관해 연구한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.95-98
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• 2006

Data collected by sensors in field are transmitted to the base station gathering all of data. Because sensors have to gather data in surroundings and periodically transmit data to the base station, it makes energy consumed much. In this paper, we propose the scheme that is to avoid traffic congestion with achievement of energy efficiency, so collected data is transmitted efficiently. This is to adjust transmission rate differently in case of increasing or decreasing traffic and minimize the energy consumption with setting ideal options up basic CSMA(Carrier Sense Multiple Access) protocol in each sensor. Through the simulation, we find the ideal CSMA options and apply the proposed scheme of traffic control mechanism to them, then show energy efficiency and effective traffic control mechanism.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.682-684
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• 2000

에너지 절약과 환경 공해분제 그리고 최근에 부각되고 있는 지구온난화 문제 등을 해결하기 위해 고효율 발전시스템인 연료전지가 주목을 받고 있다 연료전지는 연소과정 없이 화학에너지를 전기 화학적으로 직접 전기로 변환시키는 시스템으로 효율이 높고 공해 물질의 배출이 거의 없기 때문에 매우 이상적인 발전장치이다. 연료전지 발전시스템의 철거 제어기 설계를 위해 필요한 운전 조건 즉 운전온도 압력 등의 운전조건과 연료 농도 공급량이 전지의 성능에 미치는 영향에 대한 특성을분석하였고 이들을 정리하여 최적제어를 위한 기본방식을 얻기 위해 이용하였다 실재 스택에 적용하기 위한 관련 측정시스템과 제어기는 dSPACE-1103과 ControlDesk를 사용하여 구성하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.5
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• pp.499-505
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• 2015

To properly design and assess a piezoelectric vibration energy harvester, it is necessary to consider the application of an efficiency measure of energy conversion. The energy conversion efficiency is defined in this work as the ratio of the electrical output power to the mechanical input power for a piezoelectric vibration energy harvester with an impedance-matched load resistor. While previous research works employed the electrical output power for approximate impedance-matched load resistance, this work derives an efficiency measure considering optimally matched resistance. The modified efficiency measure is validated by comparing it with finite element analysis results for piezoelectric vibration energy harvesters with three different values of the electro-mechanical coupling coefficient. New findings on the characteristics of energy conversion and conversion efficiency are also provided for the two different impedance matching methods.

• Journal of Energy Engineering
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• v.4 no.3
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• pp.344-353
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• 1995

화력발전기의 주간운용계획을 수립함에 있어 여러 에너지사용에 관련된 제약조건의 지배를 받는 발전기를 효율적으로 고려할 수 있는 새로운 방법을 개발하였다. 우선 이를 위하여 에너지제약을 고려한 운용계획문제를 Lagrangian Relaxation법에 의해 모델링하였다. 또한 에너지제약을 만족하는 최적의 화력발전기의 기동정지계획 및 발전출력을 원문제 내에서 구할 수 있도록 하였으며, 쌍대문제를 효율적으로 풀 수 있는 알고리즘을 개발하여 보다 빠르고 정확한 해를 구할 수 있도록 하였다. 제안한 방법을 시험계통 및 대규모 실계통에 적용하여 유용성을 검증하였다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.39-43
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• 2004

국제적인 환경 규제 문제($CO_2$, SF$_{6}$(육불화황), PFC (과불화화합물) 등)가 새로운 무역장벽으로 등장하여 우리나라 주요 산업 부문에 미치는 영향이 점차 현실로 나타나고 있다. 이러한 환경 규제에 적절한 대처를 하기 위해 에너지 소비 증가와 이에 따르는 에너지 소비 패턴 및 인식에 대한 새로운 접근 방법이 요구되고 있다. 그동안 전력기기의 고효율화, 에너지 효율 향상과 수요관리 강화, 미활용 에너지원의 이용률 제고, 집단에너지 보급 확대 등 하드웨어적인 기술개발에 중점을 두고 추진되었으나, 앞으로는 전원설비, 전력전송 설비, 부하설비 등의 최적 설계기술을 통한 에너지절약 기술개발과 같은 소프트웨어적인 기술 개발이 요청되고 있다. (중략)