• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.65-74
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• 2003

In this Paper, we propose a downlink service admission strategy that considers users QoS requirements by using a novel service quality prediction index for multi-service WCDMA mobile systems. The Proposed downlink service admission strategy is obtained by computing average received Power of each service, assuming a relative other-cell interference factor. With the proposed method we obtain a downlink service admission region where users of different services properly can be admitted. And adding the fairness at the proposed downiinh service admission strategy, we Propose another downlink service admission strategy. In the numerical examples, the downlink service admission region with fairness and the downlink service admission region without fairness of voice service and data services are obtained by proposed downlink service admission strategies, respectively.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1855-1865
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• 2018

This paper presents a control strategy for voltage-controlled multi-function distributed generation (DG) combined with an active power filter (APF) and a reactive power compensator. The control strategy is based on droop control. As a result of local nonlinear loads, the voltages of the point of common coupling (PCC) and the currents injecting into the grid by the DG are distorted. The power quality of the PCC voltage can be enhanced by using PCC harmonic compensation. In addition, with the PCC harmonic compensation, the DG offers a low-impedance path for harmonic currents. Therefore, the DG absorbs most of the harmonic currents generated by local loads, and the total harmonic distortion (THD) of the grid connected current is dramatically reduced. Furthermore, by regulating the reactive power of the DG, the magnitude of the PCC voltage can be maintained at its nominal value. The performance of the DG with the proposed control strategy is analyzed by bode diagrams. Finally, simulation and experimental results verify the proposed control strategy.

• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.13-18
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• 2023

A subway station is a prominent multi-purpose facility where the quantitative management of fine dust, generated by various factors, is conducted. Recently, eco-friendly air purification methods using air-purifying plants are being discussed, with the focus on biofiltration through vegetation. Previous research in this field has confirmed the reduction effects of transition metals such as Fe, which have been identified as harmful to human health. This study aimed to identify the sources of fine dust dispersion within subway stations and derive an efficient operational strategy for air-purifying plants that takes into account the behavior characteristics of fine dust within multi-purpose facilities. The experiment monitored regional fine dust levels through IAQ stations established based on prior research. Also, the data was analyzed through time-series and correlation analyses by linking it with passenger counts at subway stations and the frequency of train stops. Furthermore, to consider energy efficiency, we conducted component-specific power consumption monitoring. Through this study, we were able to derive the optimal operational strategy for air-purifying plants based on time-series comprehensive analysis data and confirm significant energy efficiency.

• Smart Structures and Systems
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• v.26 no.3
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• pp.373-390
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• 2020

Hybrid simulation (HS) is a versatile tool for structural performance evaluation under dynamic loads. Although real structural responses are often multiple-directional owing to an eccentric mass/stiffness of the structure and/or excitations not along structural major axes, few HS in this field takes into account structural responses in multiple directions. Multi-directional loading is more challenging than uni-directional loading as there is a nonlinear transformation between actuator and specimen coordinate systems, increasing the difficulty of suppressing loading error. Moreover, redundant actuators may exist in multi-directional hybrid simulations of large-scale structures, which requires the loading strategy to contain ineffective loading of multiple actuators. To address these issues, lately a new strategy was conceived for accurate reproduction of desired displacements in bi-directional hybrid simulations (BHS), which is characterized in two features, i.e., iterative displacement command updating based on the Jacobian matrix considering nonlinear geometric relationships, and force-based control for compensating ineffective forces of redundant actuators. This paper performs performance validation and application of this new mixed loading strategy. In particular, virtual BHS considering linear and nonlinear specimen models, and the diversity of actuator properties were carried out. A validation test was implemented with a steel frame specimen. A real application of this strategy to BHS on a full-scale 2-story frame specimen was performed. Studies showed that this strategy exhibited excellent tracking performance for the measured displacements of the control point and remarkable compensation for ineffective forces of the redundant actuator. This strategy was demonstrated to be capable of accurately and effectively reproducing the desired displacements in large-scale BHS.

• Journal of IKEEE
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• v.22 no.2
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• pp.455-459
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• 2018

In this paper, proposed a multi-channel charging control strategy for electric vehicle. This control strategy can adjust the charging power according to the calculated state-of-charge (SOC). Electric vehicle (EV) charging system using Particle Swarm Optimization (PSO) algorithm is proposed. A stochastic optimization algorithm technique such as PSO in the time-of-use (TOU) price used for the energy cost minimization. Simulation results show that the energy cost can be reduced using proposed method.

• Proceedings of the Korea Database Society Conference
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• 1995.12a
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• pp.191-196
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• 1995

PC에서 가상 현실을 구현하고 사용자가 원하는 대로 장면을 이동시키고, Movie 화면을 돌려보면서 원하는 물체를 누르면 필요한 정보와 멀티미디어 효과를 얻도록 오쏘링 할 수 있다면 PC에서의 멀티미디어는 한단계 진보 할 수 있을 것이다. 그것이 바로 QuickTime V.R인 것이다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.411-412
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• 2011

• Journal of Information Processing Systems
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• v.8 no.3
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• pp.471-482
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• 2012

For disaster exploration and surveillance application, this paper aims to present a novel application of a multi-robot agent based on WSN and to evaluate a multi-hop communication caused by the robotics correspondingly, which are used in the uncertain and unknown subterranean tunnel. A Primary-Scout Multi-Robot System (PS-MRS) was proposed. A chain topology in a subterranean environment was implemented using a trimmed ZigBee2006 protocol stack to build the multi-hop communication network. The ZigBee IC-CC2530 modular circuit was adapted by mounting it on the PS-MRS. A physical experiment based on the strategy of PS-MRS was used in this paper to evaluate the efficiency of multi-hop communication and to realize the delivery of data packets in an unknown and uncertain underground laboratory environment.

• Journal of the military operations research society of Korea
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• v.24 no.1
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• pp.98-109
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• 1998

This study develops a maintenance strategy for a reparable 2-unit standby system. The maintenance strategy implies the waiting time to call the repair facility when the unit-1 fails. Almeida and Souza set up the multi-attribute utility function consisting of system availability and repair cost for several maintenance strategies and decide the optimal maintenance strategy that maximize the expected value of the utility function. We decide the optimal maintenance strategy satisfying the following two criteria about the utility function : maximum variance using Almeida and Souza's utility function. It both criteria are not satisfied at the same time for every strategies, the strategy maximizing the lower confidence limit for expected utility function is regarded as an optimal one.

• Asia Marketing Journal
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• v.15 no.4
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• pp.187-200
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• 2014

The case study of OB shows dramatic market dynamics between leader brand vs. follower brand similar to Kirin vs. Asahi in Japan for two decades. Almost 20yrs ago, the brand status of OB was dramatically fallen because of the environmental pollution of subsidiary company and harsh competition of rivalry brand. But OB made a ground change in its brand strategy. OB departed from the pride in its past to bet on the new. OB decided to vitalize Cass brand through brand portfolio strategy. They deployed 3 phase articulated marketing plans; Phase I, Acquisition of Cass brand through M&A and strategic segmentation/targeting (1993-2005), Phase 2 - Mega Brand Strategy through Line Extension(2006-2009), Phase 3 - Experiential Marketing focused on Young Culture (2010- present). Finally, OB restored not only brand reputation of Cass and other brands but dominant market position in beer market. Now Cass has been growing rapidly in the last 20 years achieving 50% M/S. The three phases shows the typical successful process of brand management and revitalization adopting brand concept management and S-T-P strategy of manufacturing company.