• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2527-2545
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• 2016

Measuring the similarity of given samples is a key problem of recognition, clustering, retrieval and related applications. A number of works, e.g. kernel method and metric learning, have been contributed to this problem. The challenge of similarity learning is to find a similarity robust to intra-class variance and simultaneously selective to inter-class characteristic. We observed that, the similarity measure can be improved if the data distribution and hidden semantic information are exploited in a more sophisticated way. In this paper, we propose a similarity learning approach for retrieval and recognition. The approach, termed as LDA-FEK, derives free energy kernel (FEK) from Latent Dirichlet Allocation (LDA). First, it trains LDA and constructs kernel using the parameters and variables of the trained model. Then, the unknown kernel parameters are learned by a discriminative learning approach. The main contributions of the proposed method are twofold: (1) the method is computationally efficient and scalable since the parameters in kernel are determined in a staged way; (2) the method exploits data distribution and semantic level hidden information by means of LDA. To evaluate the performance of LDA-FEK, we apply it for image retrieval over two data sets and for text categorization on four popular data sets. The results show the competitive performance of our method.

• Journal of Communications and Networks
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• v.12 no.2
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• pp.130-139
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• 2010

Environmental issues and the need to reduce energy consumption for lowering operating costs have pushed power efficiency to become one of the major issues of current research in the field of wireless networks. This paper addresses a number of multiple input multiple output (MIMO) precoding and scheduling techniques across the PHY and MAC layers that can operate under a reduced link budget and collectively improve the transmit power efficiency of a base station, while maintaining the same levels of service. Different MIMO transmission and precoding schemes proposed for LTE, achieving varying degrees of multiuser diversity in both the time, frequency as well as the space domain, are examined. Several fairness-aware resource allocation algorithms are applied to the considered MIMO schemes and a detailed analysis of the tradeoffs between power efficiency and quality of service is presented. This paper explicitly examines the performance of a system serving real-time, VoIP traffic under different traffic loading conditions and transmit power levels. It is demonstrated that by use of efficient scheduling and resource allocation techniques significant savings in terms of consumed energy can be achieved, without compromising QoS.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.315-320
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• 2009

Thermoeconomics or exergoeconomics can be classified into the three fields of cost estimating, cost optimization, and internal cost analysis. The objective of cost estimating is to estimate each unit cost of product and allocate each cost flow of product such as electricity or hot water. The objective of optimization is to minimize the input costs of capital and energy resource or maximize the output costs of products under the given constraints. The objective of internal cost analysis is to find out the cost formation process and calculate the amount of cost flow at each state, each component, and overall system. In this study, a new thermoeconomic methodology was proposed in the three fields. The proposed methodology is very simple and obvious. That is, the equation is only each one, and there are no auxiliary equations. Any energy including enthalpy and exergy can be applied and evaluated by this equation. As a new field, the cost allocation methodology on cool air or hot air produced from an air-condition system was proposed. Extending this concept, the proposed methodology can be applied to any complex system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.21-29
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• 2012

Person characteristics and the perception of organization climate affect on the performances associated with causes of job stress, and may induce various types of human errors. For incidence, a person's adaptation to organizational traits can influence on a person's performance with tasks assigned as well as job satisfaction, a change of occupation, etc. There are several evaluation methods such as an aptitude test to evaluate the suitability of department allocation. However, only person's traits such as an aptitude has been associated with department allocation and job assignment for the personnel management. This paper shows not only an evaluation result on the job-stress of the workers in nuclear power plants (NPPs), but also the relationships between the job-stress and the coincidences of group-personal, team-personal traits. Then, we systematically deduct a basic information on the factors to be considered to manage the organizational traits and job stress. We expect this result can contribute to enhance the organizational management against to the human errors as well as for the promotion of safety and efficiency of NPPs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.964-973
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• 2015

Ship Area Network(SAN) can monitor the status of ship in real time and minimize the maintenance costs by connecting various devices to the network. In particular, among researches on SAN, Wireless Sensor Network using sensor nodes that is low-cost, low-power, and multifunctional has a number of advantages. In this paper, we propose cluster-based multi-channel algorithm considering the energy efficiency in wireless sensor network in a ship. The proposed algorithm shows the result of improvement of throughput and energy efficiency, because it reduces interference between clusters by using channel allocation algorithm that is distributed and dynamic.

• Journal of Platform Technology
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• v.11 no.1
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• pp.3-10
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• 2023

Unmanned Aerial Vehicles (UAVs) have gained significant attention in 5G and 6G wireless networks due to their high flexibility and low hardware costs. However, UAV communication is still challenged by blockage and energy consumption issues. Reconfigurable Intelligent Surfaces (RISs) have emerged as a promising solution to these challenges, enabling improved spectral efficiency and reduced energy consumption by transmitting signals to users who cannot receive signals because of the obstacles. Many previous studies have focused on minimizing power consumption and data transmission delay through phase shift and power optimization. This paper proposes an algorithm that maximizes the sum rate by including bandwidth optimization. Simulation results demonstrate the effectiveness of the proposed algorithm.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.9-16
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• 2013

An experiment was conducted to evaluate the biochemical adverse effect of increased carbon dioxide in seawater on marine polychaete, Perinereis aibuhitensis. We measured the available energy reserves, Ea (total carbohydrate, protein, and lipid content) and the energy consumption, Ec (electron transport activity) of Perinereis aibuhitensis exposed for 7-d to a range of $CO_2$ concentration such as 0.39 (control =390 ppmv), 3.03 (=3,030 ppmv), 10.3 (=10,300 ppmv), and 30.1 (=30,100 ppmv) $CO_2$ mM, respectively. The cellular energy allocation (CEA) methodology was used to assess the adverse effects of toxic stress on the energy budget of the test organisms. The results of a decrease in CEA effect of increased carbon dioxide in seawater from all individual in Ea and Ec. Increase of carbon dioxide reduced pH in seawater, significantly. The chemical changes in sea- water caused by increasing $pCO_2$ might cause stresses to test organisms and changes in the cellular energy allocations. Results of this study can be used to understand the possible influence of $CO_2$ concentration increased by the leakage from sub-sea bed storage sites as well as fossil fuel combustion on marine organisms.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.1
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• pp.79-95
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• 1993

MARKAL (MARKet ALlocation) Model, one of the most sophisticated energy technology assessment model is applied to finding the optimum mix of energy sources and evaluating energy technology competitiveness in Korea. The model is capable of handling Multiple Objective Linear Programming to test the related cost minimization and environmental control function. In this paper three environmental regulation scenarios are observed including 10% and 20% reduction of carbon dioxide emission level. For the purpose of establishing the basic data base, Korea Reference Engergy System is also developed on the base of the year 1989 with technology utilization and energy flow analysis.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.511-515
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• 2012

At the moment, with an interest in renewable energy sources (RES) that continue to grow its penetration will be expected to considerably increase in the future power system. However, this penetration of RES leads to new challenges to be solved in electric power systems. In this paper, optimal configuration of renewable energy resources and operation strategy is presented. By using this methodology for allocation of the optimal sizes and types, system operational efficiency and stability of the microgrid will be maximized.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.256-264
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• 2015

Energy harvesting devices have been proposed for sensor networking applications where batteries cannot be replaced, and cooperative communication schemes have been used to increase energy efficiency for wireless systems. Here, we develop transmission scheduling schemes for multi-terminal cooperative energy harvesting networks that maximize the packet delivery ratio, i.e., the probability that an event is reported successfully. We see that the proposed scheme provides virtually the same performance as the state-of-the-art threshold-based scheme, but does not require auxiliary parameter optimization. The proposed scheme also permits extensions to multiple cooperating nodes and sources, and it can be modified to accommodate fairness constraints.