• 로봇학회논문지
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• 제6권2호
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• pp.130-140
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• 2011

This paper proposes an optimal posture for the task-oriented movement of dual arm manipulator. A stability criterion function which consists of three kinds of feature-representative parameters has been utilized to define the optimal posture. The first parameter is the force which is applied to the object. The torque of each joint and position of arm are attained from the current sensor and encoder, respectively. From these two data, the applied force to an object is estimated using sum of vectors of the joint torques estimated from the measured current. In order to investigate the robustness of each posture, the variation of the end-effector from the encoder information has been utilized as the second parameter. And for the last parameter for the optimality, the total energy consumption has been used. The total consuming energy of each posture can be computed from the current information and the battery voltage. The proposed robot structure consists of a mobile inverted pendulum and dual manipulators. In order to define the optimal posture for the each object, external disturbances are applied to the mobile inverted pendulum robot and the first and second parameters are investigated to find the optimal posture among the pre-selected most representative postures. Finally, the proposed optimal posture has been verified by the proposed stability criterion function which consists of total force to the object, the fluctuation of the end-effector position, and total energy consumption. The effectiveness of the proposed algorithms has been verified and demonstrated through the practical simulations and real experiments.

• 드라이브 ㆍ 컨트롤
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• 제17권2호
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• pp.38-44
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• 2020

Various efforts have been initiated to reduce the energy consumption of the compressor as it is one of the approaches to saving a large portion of the fixed cost of the production site. Various results of reducing the energy consumption of the compressor have been reported, but to reduce the energy consumption of the compressors fundamentally, regular management of the compressor should ensure optimum operation. This requires periodic on-site visits by experts, but is often overlooked as a cost issue, resulting in the use of the compressor in low-efficiency conditions. Thus, it is necessary to develop a low-cost evaluation technology for compressor condition monitoring and efficiency analysis to ensure that the compressor is always driven at the optimum efficiency without imposing undue burden on the compressor user. In this study, a sensor was installed at the inlet, outlet, and power supply of the compressor, and a method for evaluating the energy consumption of the compressor using the minimum sensor was derived. The experimental results are presented to show the validity of the proposed method. It was confirmed that the energy consumption of the compressor can be easily as well as efficiently evaluated by using the method developed in this study.

• 한국자동차공학회논문집
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• 제16권4호
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• pp.143-150
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• 2008

EGR(exhaust gas recirculation) is an attractive means of improving the fuel economy of spark ignition engines, as it offers the benefits of charge dilution (lower pumping and cooling losses) while allowing stoichiometric fuelling to be retained for applications using the three-way catalysts. However, the occurrence of excessive cyclic variation with high EGR normally prevents substantial fuel economy improvements from being achieved in practice. Therefore, the optimum EGR rate in Gasoline-Hybrid engine should be carefully determined in order to achieve low fuel consumption and low exhaust emission. In this study, 2 liters gasoline engine with E-EGR system was used to investigate the effects of EGR on fuel economy, combustion stability, engine performance and exhaust emissions. EGR tolerance with load variation was found to be more sensitive than with rpm variation. With optimal EGR rates, the fuel consumption was improved by 5.5% while a combustion stability was guaranteed.

• 설비공학논문집
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• 제27권6호
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• pp.313-320
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• 2015

In this paper, a method to obtain the probability distribution of room temperature and cooling load is presented, when the internal heat generation is applied to the system as a disturbance in the air conditioning system with slab cooling storage. The probability distribution of room temperature and the cooling load due to the disturbance were examined in one room of an office building. When considering only the electric power consumption as a probability component, it was found that the effect on room temperature and cooling load is small, because the probability component of the measured electric power consumption in the building is small. On the other hand, when considering the stochastic fluctuations of electric power consumption together with the heat generated by human bodies, the mean value of the cooling load was about 2,300 W and the ratio of the standard deviations was 19% (10 o'clock in second day). It was revealed that the stochastic effects of internal heat generation acting on the air conditioning system with slab cooling storage are not small.

• 전자공학회논문지CI
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• 제46권4호
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• pp.79-86
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• 2009

본 논문에서는 노드 밀도를 고려하여 클러스터를 형성함으로써 데이터 병합 효과를 최대화하고, 에너지 소모를 줄일 수 있는 새로운 클러스터링 기법을 제안한다. 이 기법은 최적의 데이터 병합율을 보장할 수 있도록 클러스터 크기를 결정하기 때문에 메시지 전송 반경을 줄이고, 클러스터간의 간섭을 최소화할 수 있다. 또한 지역적으로 인접한 다수의 노드들을 클러스터로 구성하고 멤버 노드로부터 수신된 데이터를 병합하여 전송함으로써 에너지 소모를 줄인다. 시뮬레이션을 통하여 센서 네트워크를 구성하는 노드의 에너지 소모를 최소화하면 센서 네트워크의 생존시간을 연장할 수 있음을 검증한다. 또한 제안한 클러스터링 기법이 기존의 LEACH 클러스터링 기법에 비해 성능이 우수함을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권6호
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• pp.2670-2685
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• 2020

Flying ad-hoc networks (FANETs) is a vibrant research area nowadays. This type of network ranges from various military and civilian applications. FANET is formed by micro and macro UAVs. Among many other problems, there are two main issues in FANET. Limited energy and high mobility of FANET nodes effect the flight time and routing directly. Clustering is a remedy to handle these types of problems. In this paper, an efficient clustering technique is proposed to handle routing and energy problems. Transmission range of FANET nodes is dynamically tuned accordingly as per their operational requirement. By optimizing the transmission range packet loss ratio (PLR) is minimized and link quality is improved which leads towards reduced energy consumption. To elect optimal cluster heads (CHs) based on their fitness we use k-means. Selection of optimal CHs reduce the routing overhead and improves energy consumption. Our proposed scheme outclasses the existing state-of-the-art techniques, ACO based CACONET and PSO based CLPSO, in terms of energy consumption and cluster building time.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.174-183
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• 2005

A train driving requires to n the fixed distance within given time, and it is desirable to consume low energy if necessary. Reducing energy consumption depends on the train operation modes by either manual or automatic operation. In this article, an operation to reduce energy consumption by changing modes of train operation by a driver without changing the train operation requirement is investigated. The powering model, braking model and consumed energy calculation model are developed, then simulated by using a Matlab software. The accuracy of the train dynamic model established by the simulations is verified by comparing with the real experimental data. Several simulations by various operations in the real track are executed, then the desirable pattern of train driving is found.

• 전기학회논문지
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• 제59권2호
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• pp.291-297
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• 2010

A system called demand response programs (DRP) is being introduced among various countries owing to the lack of new generation capacity and the higher fuel generation cost. It is a program which provides for the end-users to select their consumption of electricity by recognizing the value of their consumption in real time. That is, Demand Response can be defined as the changes in electric usage by end-use customers from their normal consumption patterns in response to changes in the price of electricity or other signals. It is expected that the effects of DRP are preventing price spike, improving supply reliability and social welfare and increasing option of customers. Considering the customer's thermal comfort zone, this paper determines the most profitable combination of optimal incentives and amounts of load reduction for a retailer to maximize profits according to predicted outdoor temperatures while implementing DRP.

• 한국통신학회논문지
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• 제37권5B호
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• pp.327-337
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• 2012

릴레이를 사용한 시스템에서 최적의 릴레이 위치에 대한 연구가 많이 진행되어 왔지만, 지금까지는 송신단과 릴레이의 전송 전력의 합이 제한된 경우에 전송 용량을 최대화하는 연구가 대부분이었다. 그러나 Ad-hoc 네트워크와 같이 릴레이가 제한된 용량의 배터리를 에너지원으로 사용하는 경우, 에너지 소모를 효율적으로 절약하는 것이 필요하다. 본 논문은 AF(Amplify-and-Forward) 릴레이를 사용한 두 홉 시스템에서 수신단의 신호 대 잡음비가 고정된 경우, 특정 전송 품질을 만족시키기 위해 릴레이에서 사용하는 전력을 최소화하는 최적 릴레이 위치 선정 방안을 제안한다. 모의실험을 통해 Ad-hoc 환경에서의 제안된 기법이 에너지 소모 측면에서 더 효율적임을 보이고, 다중 홉으로 확장된 시스템에서 제안된 기법의 경우 더 낮은 전송실패확률을 갖는 것을 확인한다.

• Journal of Magnetics
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• 제22권2호
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• pp.203-213
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• 2017

Magnetically suspended control & sensitive gyroscope (MSCSG) is a novel type of gyroscope with the integration of attitude control and attitude angular measurement. To improve the precision and reduce the power consumption of Lorentz Force-type Magnetic Bearing (LFMB), the air gap flux density distribution of LFMB has been studied. The uniformity of air gap flux density is defined to qualify the uniform degree of the air gap flux density distribution. Considering the consumption, the average value of flux density is defined as well. Some optimal designs and analyses of LFMB are carried out by finite element simulation. The strength of the permanent magnet is taken into consideration during the machining process. To verify the design and simulation, a high-precision instrument is employed to measure the 3-dimensional magnetic flux density of LFMB. After measurement and calculation, the uniform degree of magnetic flux density distribution reaches 0.978 and the average value of the flux density is 0.482T. Experimental results show that the optimal design is effective and some useful advice can be obtained for further research.