• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.453-462
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• 2016

This paper proposes a torque control method for surface mounted permanent magnetic synchronous motor (PMSM) driven by a 2-level voltage source driven inverter, which has fast torque response and small torque ripple. The proposed torque control method follows the finite control set model predictive control (FCS-MPC) strategy. A reference state is derived at each time step for the given time varying torque reference and the cost index is defined so that the tracking error for this reference state should be penalized. The choice of an optimal output voltage vector is made first from the 6 possible active voltage vectors of the 2-level voltage source inverter. Then a modulation factor for the chosen optimal voltage vector is obtained so that the torque ripple can be reduced further. It is shown that the proposed FCS-MPC control method yields fast torque tracking response and small torque ripple through simulation and experiments.

• Journal of the Korean housing association
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• v.14 no.6
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• pp.1-13
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• 2003

Housing supply ratio in Ulsan area has soared up to 91% recently. Therefore, developing a successful marketing strategy is an essential part of apartment sales success in Ulsan area. The purpose of this study is identifying the status of satisfaction level, moving motivation, the level of housing choosing behavior, and housing needs of the apartments for making a marketing strategy. The survey uses questionnaires which are delivered to the 545 housewives who live in 20 pyoung or 30 pyoung apartment in Ulsan area. The research uses a survey questionnaire for gathering a set of statistically-reasonable number of data among one million population of Ulsan metropolitan area. The frequency test and F-test are used for the analysis of the results. The results of empirical analyses provide the following major findings： 1) housing satisfaction of Buk-ku residents is higher than that of the residents of the other area, 2) neighborhood environment improvement and physical environment improvement are important factors of housing moving motivations, 3) view and lighting are important requirements of the housing, 4) the level of housing choosing efforts are more active in the residents of Joong-ku and Dong-ku than those of Nam-ku and Buk-ku.

• Journal of Fashion Business
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• v.27 no.2
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• pp.88-107
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• 2023

This study aimed to understand the current status of practice for sustainability in luxury fashion brands. A total of five luxury brands (Louis Vuitton, Hermès, Gucci, Burberry, and Prada) were selected. Each company's official website, sustainability reports, and articles on sustainability practices were compiled. In addition, analysis was performed based on criteria of sustainability such as environmental, social, economical, and cultural dimensions. As a result, the biggest commonality of the five brands was that they promoted the most active change in the environment. These brands tried to reduce energy consumption in materials and production processes. Among them, Burberry, Gucci, and Louis Vuitton had their own departments for sustainability. However, there were differences in strategies of activities between brands for social, economical, and cultural sustainability. Among the five companies, Burberry and Gucci pursued sustainability strategies the most aggressively. They separated their sustainability strategies in terms of environmental, social, economical, and cultural aspects and shared them with consumers. A set of outcomes for the plan were provided as objective data. The sustainable management strategy has become a key strategy for long-term growth of the luxury brand market. To survive in the market, luxury brands should elaborate sustainable management strategies and actively share them with consumers.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1006-1017
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• 2015

This paper presents a finite control set model predictive control (FCS-MPC) strategy for the AC/DC matrix converter used in grid-connected battery energy storage system (BESS). First, to control the grid current properly, the DC current is also included in the cost function because of input and output direct coupling. The DC current reference is generated based on the dynamic relationship of the two currents, so the grid current gains improved transient state performance. Furthermore, the steady state error is reduced by adding a closed-loop. Second, a Luenberger observer is adopted to detect the AC input voltage instead of sensors, so the cost is reduced and the reliability can be enhanced. Third, a switching state pre-selection method that only needs to evaluate half of the active switching states is presented, with the advantages of shorter calculation time, no high dv/dt at the DC terminal, and less switching loss. The robustness under grid voltage distortion and parameter sensibility are discussed as well. Simulation and experimental results confirm the good performance of the proposed scheme for battery charging and discharging control.

• International Commerce and Information Review
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• v.11 no.2
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• pp.343-367
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• 2009

This research is about global investment for managing the important position, what Korea is doing in World's main market. Considering there are some differences between developed countries' model and developing countries' model in doing direct overseas investment, they target to get political agreement and develop the new invest plan and strategy by understanding changes of Korean manufacturing companies in direct overseas investment between 2000 and 2007 and analyzing the change of yearly investment motivation factors and determining factors for investment. The result from this result let us know that company should develop their own idea for their competitive advantage by doing direct overseas investment with the existing theory which convinces the need of competitive advantage for investing overseas. I set actual model and analyze results from it with the considering that it is so important to get knowledge and information for globalizing companies to invest overseas and companies, which want to be world leading ones for their field through innovation and changes, need to have more active strategy. And, the overseas investment, which was already done in other countries, 1. Review its realities and tendency in terms of investing countries, investing industries, and its scale. 2. Set up an actual model, based on strategic combination of investing location select and determination of Korean manufacturing companies and yearly investing factor-effect analysis. 3. Analyze how the situational factors have influenced and what factors would be considered for direct overseas investment. From the analyzing result, even though it is fairly true that raising wage and getting resources, avoiding customs, and developing alternating industries for export had influenced at the beginning, overseas investing companies' policy will be influenced by the results from studying marketing-pursuit type, which emphasizes to manage trade income and outgo, keeping the balance in the black, ensuring raw materials, local producing and manufacturing by using low-wage people for local sale, and situation for changing investing tendency as service industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.16-23
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• 2018

Chaos is one of the most significant topics in nonlinear science, and has been intensively studied since the Lorenz system was introduced. One characteristic of a chaotic system is that the signals produced by it do not synchronize with any other system. It therefore seems impossible for two chaotic systems to synchronize with each other, but if the two systems exchange information in just the right way, they can synchronize. This paper addresses the problem of synchronization in a modified Lorenz chaotic system based on active control, sliding mode control, and the Lyapunov stability theory. The considered synchronization scheme consists of identical drive and response generalized systems coupled with linear state error variables. For this, a brief overview of the modified Lorenz chaotic system is given. Then, control rules are derived for chaos synchronization via active control and slide mode control theory, with a strategy for solving the chattering problem. The asymptotic stability of the overall feedback system is established using the Lyapunov stability theory. A set of computer simulation works is presented graphically to confirm the validity of the proposed method.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.19-22
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• 2005

In order to achieve high capacity and reliable link quality in user communication, this paper proposes a new concept of virtual cell: the Dual Virtual Cell(DVC), and DVC employment strategy based on DWCS. The proposed system uses two kinds of virtual cell. One is the AVC(Active Virtual Cell) which exists for actual traffic and the other is the CVC(Candidate Virtual Cell) which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. And also this system aims to reduce MT's overloads and acheive a prompt link change successfuly by introducing DVC structure which makes it possible for network to monitor real-time channel and to conrol communication links. The proposed system constructs DVC by using antenna selection method and improves frame error performance with employing Space-Time Trellis Code(STTC).

• Journal of Power Electronics
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• v.8 no.1
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• pp.81-90
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• 2008

This paper presents an investigation of a voltage and frequency controller for an isolated asynchronous generator (IAG) driven. by a wind turbine and supplying 3-phase 4-wire loads to the isolated areas where a grid is not accessible. The control strategy is based on the indirect current control of the VSC (voltage source converter) using the frequency PI controller. The proposed controller consists of three single-phase IGBT (Insulated Gate Bipolar Junction Transistor) based VSC, which are connected to each phase of the IAG through three single phase transformers and a battery at their DC link. The controller has the capability of controlling reactive and active powers to regulate the magnitude and frequency of the generated voltage, harmonic elimination, load balancing and neutral current compensation. The proposed isolated system is modeled and simulated in MATLAB using Simulink and PSB (Power System Block-set) toolboxes to verify the performance of the controller.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.173-178
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• 1989

Optimal Power Flow (OPF) solution by the Newton's method provides a reliable and robust method to classical OPF problems. The major challenge in algorithm development is to identify the binding inequalities efficiently. This paper propose a simple strategy to identify the binding set. From the mechanism of penalty shifting with soft penalty in trial iteration, a active binding sit is identified automatically. This paper also suggests a technique to solve the linear system whore coefficients are presented by the matrix. This implementation is highly efficient for sparsity programming. Case study for 3,5,14,118,190 bus and practrical KEPCO 305 bus system are performed as well.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.45-52
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• 2005

A general approximate optimization technique by sequential design domain(SDD) did not save response values for getting an approximate function in each step. It has a disadvantage at aspect of an expense. In this paper, previous response values are recycled for constructing an approximate function. For this reason, approximation function is more accurate. Accordingly, even if we did not determine move limit, a system is converged to the optimal design. Size and shape optimization using approximate optimization technique is carried out with SDD. Algorithm executing Pro/Engineer and ANSYS are automatically adopted in the approximate optimization program by SDD. Convergence criterion is defined such that optimal point must be located within SDD during the three steps. The PLBA(Pshenichny-Lim-Belegundu-Arora) algorithm is used to solve approximate optimization problems. This algorithm uses the second-order information in the direction finding problem and uses the active set strategy.