• 한국항해항만학회지
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• 제32권10호
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• pp.765-770
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• 2008

본 논문은 하이브리드 전기 추진 시스템의 전력 제어에 관한 연구를 수행하였다. 하이브리드 전기 추진 시스템은 기본적으로 발전기와 축전지 전원을 이용하여 선박을 추진하는 시스템이다. 하이브리드 추진 시스템은 공급되는 전력을 최소화하기 위한 제어 알고리즘으로 동작한다. 본 논문에서는 하이브리드 전기 추진 시스템의 효율을 증가시키기 위한 축전지 충전 알고리즘을 제안한다. 실험을 통하여 제어 알고리즘이 하이브리드 전기 추진 시스템에서 정상적으로 동작하는 것을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권10호
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• pp.4865-4886
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• 2017

The user experience of practical indoor power line communication (PLC) applications is greatly affected by the system quality-of-service (QoS) criteria. With a general broadcast-and-multi-access (BMA) relay scheme, in this work we investigate the joint source and relay power optimization of the amplify-and-forward (AF) relay systems used under indoor broad-band PLC environments. To achieve both time diversity and spatial diversity from the relay-involved PLC channel, which is time-varying in nature, the source node has been configured to transmit an identical message twice in the first and second signalling phase, respectively. The QoS constrained power allocation problem is not convex, which makes the global optimal solution is computationally intractable. To solve this problem, an alternating optimization (AO) method has been adopted and decomposes this problem into three convex/quasi-convex sub-problems. Simulation results show the fast convergence and short delay of the proposed algorithm under realistic relay-involved PLC channels. Compared with the two-hop and broadcast-and-forward (BF) relay systems, the proposed general relay system meets the same QoS requirement with less network power assumption.

• 한국통신학회논문지
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• 제29권10B호
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• pp.849-856
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• 2004

본 논문은 시분할 슈퍼프레임을 사용하는 무선 네트워크에서 슈퍼 프레임을 형성하는 새로운 알고리듬을 제안하고 있다. 제안된 알고리듬은 높은 성능과 안정성, 오류 저항성을 제공할 뿐만 아니라, 전력 절약을 쉽게 하는 특징도 가지고 있다. 다양한 종류의 트래픽 아래서의 시뮬레이션을 통해 제안된 알고리듬의 성능을 응답시간, 비콘손실에 대한 오류 저항성 등의 성능지수로 분석하였다. 분석결과, 제안된 알고리듬이 기존에 제안된 알고리듬들의 장점을 이어받으면서도, 단점을 크게 줄였음을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1884-1903
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• 2019

Device-to-Device (D2D) communications can provide proximity based services in the future 5G cellular networks. It allows short range communication in a limited area with the advantages of power saving, high data rate and traffic offloading. However, D2D communications may reuse the licensed channels with cellular communications and potentially result in critical interferences to nearby devices. To control the interference and improve network throughput in overlaid D2D cellular networks, a novel channel assignment approach is proposed in this paper. First, we characterize the performance of devices by using Poisson point process model. Then, we convert the throughput maximization problem into an optimal spectrum allocation problem with signal to interference plus noise ratio constraints and solve it, i.e., assigning appropriate fractions of channels to cellular communications and D2D communications. In order to mitigate the interferences between D2D devices, a cluster-based multi-channel assignment algorithm is proposed. The algorithm first cluster D2D communications into clusters to reduce the problem scale. After that, a multi-channel assignment algorithm is proposed to mitigate critical interferences among nearby devices for each D2D cluster individually. The simulation analysis conforms that the proposed algorithm can greatly increase system throughput.

• 한국정보통신학회논문지
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• 제24권7호
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• pp.925-934
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• 2020

본 연구는 선박의 에너지 효율을 향상시키기 위하여 에너지 절감 시스템 (ESS, Energy Saving System)의 알고리즘을 선박운항 특성에 적합하게 설계하고, 특정 시스템을 탑재한 선박의 운항 특성을 바탕으로 에너지 소비 양상을 분석하여 운항 비용을 절감할 수 있도록 하는 기법에 대하여 연구한다. 이를 위해 발전체계를 기반으로 선박의 추진 체계 특성을 반영한 에너지 효율을 높일 수 있는 효율적인 시스템을 구현한다. 연구대상 선박은 LNG 운반선에 탑재된 HVACS(Heating, Ventilation and Air Conditioning) 대상으로 연구를 진행하며, 이를 기반으로 미래형 기반 선박인 전기추진선박 및 자율운항선박 등에 적용할 수 있도록 확장성을 가진 에너지 절감 기법을 제안한다.

• 한국산학기술학회논문지
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• 제13권10호
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• pp.4902-4909
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• 2012

본 논문에서는 TOU 요금제 기반에서 제어구간 설정방법을 사용한 건물 냉방시스템 실내온도 제어 알고리즘을 제안한다. 건물 실내온도를 최적제어하기 위한 제어구간 설정은 스위칭방법과 선형계획법을 사용하고 냉방시스템 사용요금은 TOU와 피크 요금을 포함하여 산정한다. 시뮬레이션을 통해 제안한 제어구간 설정방법을 적용하면 전력 사용에 따른 비용의 절감과 피크 전력 절감을 확인할 수 있다.

• 한국산학기술학회논문지
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• 제14권5호
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• pp.2536-2543
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• 2013

본 논문에서는 단일존 빌딩의 모델링과 PSO 알고리즘을 이용한 냉방시스템 제어구간 건물 실내온도 제어 알고리즘을 제안한다. 최적제어를 하기 위한 제어구간 설정은 스위칭방법과 PSO 알고리즘을 사용하고 냉방시스템 사용요금은 TOU와 피크요금을 포함 하여 산정한다. 시뮬레이션을 통해 제안한 제어구간 설정방법을 적용하면 전력 사용에 따른 비용의 절감과 피크전력 절감을 확인할 수 있다.

• 한국공작기계학회논문집
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• 제17권6호
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• pp.35-42
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• 2008

Most of tasks for vertical surface work in shipyard have been accomplished by human workers. However, such manual work often causes injury to workers, also the production cost becomes high due to increasing individual wage. To cope with the circumstance, shipbuilding companies try to introduce wall-climbing robots for carrying out such kind of tasks. In designing a wall-climbing robot, it is essential to minimize its own weight to improve the performance such as moving speed and power saving. For such purpose. this study proposes a method of optimal design for a wall-climbing robot using a genetic algorithm with multi-objective function. Specifically, the thickness of the robot base is minimized to reduce the weight while maintaining the allowable strength and avoiding the resonance frequencies. The proposed method is applied to the design of a wall-climbing robot, and the result shows that the method is useful at an early design stage.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.159-162
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• 2001

This paper is proposed an efficiency optimization operation algorithm for synchronous reluctance motor (SynRM) using current phase angle control technique. The SynRM has to controlled with the optimal current phase angles with load and operation speed variation, to obtain high efficiency over the wide speed ranges. An efficiency optimization condition in SynRM which minimizes the copper and iron losses is derived based on the equivalent circuit model of the machine. The objective of the efficiency optimization control algorithm compensating the optimum current angle, is to seek a combination of d and q-axis current components which provides minimum losses at a certain operating point in steady state. The usefulness of the proposed efficiency optimization control is verified through vector-controlled inverter system with the SynRM.

• Environmental Engineering Research
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• 제21권4호
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• pp.409-419
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• 2016

As a major energy consumption province, the issue about the carbon emissions in Hebei Province, China has been concerned by the government. The carbon emissions can be effectively reduced due to a more rational energy consumption structure. Thus, in this paper the constraint of low carbon emissions is considered as a foundation and four energies--coal, petroleum, natural gas and electricity including wind power, nuclear power and hydro-power etc are selected as the main analysis objects of the adjustment of energy structure. This paper takes energy cost minimum and carbon trading cost minimum as the objective functions based on the economic growth, energy saving and emission reduction targets and constructs an optimization model of energy consumption structure. And empirical research about energy consumption structure optimization in 2015 and 2020 is carried out based on the energy consumption data in Hebei Province, China during the period 1995-2013, which indicates that the energy consumption in Hebei dominated by coal cannot be replaced in the next seven years, from 2014 to 2020, when the coal consumption proportion is still up to 85.93%. Finally, the corresponding policy suggestions are put forward, according to the results of the energy structure optimization in Hebei Province.