• Journal of Electrical Engineering and Technology
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• v.6 no.6
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• pp.786-792
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• 2011

The present paper presents an optimal capacitor placement (OCP) algorithm for voltagestability enhancement. The OCP issue is represented using a mixed-integer problem and a highly nonlinear problem. The hybrid particle swarm optimization (HPSO) algorithm is proposed to solve the OCP problem. The HPSO algorithm combines the optimal power flow (OPF) with the primal-dual interior-point method (PDIPM) and ordinary PSO. It takes advantage of the global search ability of PSO and the very fast simulation running time of the OPF algorithm with PDIPM. In addition, OPF gives intelligence to PSO through the information provided by the dual variable of the OPF. Numerical results illustrate that the HPSO algorithm can improve the accuracy and reduce the simulation running time. Test results evaluated with the three-bus, New England 39-bus, and Korea Electric Power Corporation systems show the applicability of the proposed algorithm.

• Bulletin of the Korean Mathematical Society
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• v.48 no.3
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• pp.555-574
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• 2011

It is well known that the mathematical models provide very important information for the research of human immunodeciency virus type. However, the infection rate of almost all mathematical models is linear. The linearity shows the simple interaction between the T-cells and the viral particles. In this paper, a differential equation model of HIV infection of $CD4^+$ T-cells with Crowley-Martin function response is studied. We prove that if the basic reproduction number $R_0$ < 1, the HIV infection is cleared from the T-cell population and the disease dies out; if $R_0$ > 1, the HIV infection persists in the host. We find that the chronic disease steady state is globally asymptotically stable if $R_0$ > 1. Numerical simulations are presented to illustrate the results.

• Journal of the Korean Operations Research and Management Science Society
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• v.19 no.2
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• pp.217-228
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• 1994

This paper presents a new integer formulation (Type III ALB) for a single model assembly line balancing problem. The objective of the formulation is to minimize the total idle time, which is defined as the product of the number of work stations and the cycle times minus the total work content. This formulation considers currently existing Type I (minimizing the number of work stations for a given cycle time) and type II (minimizing the cycle time for a given number of work stations) formulations as its special cases and provides the global minimum solutions of the cycle time and the number of work stations. This information would be of great value to line designers involved in designing new assembly lines and rebalancing old lines under flexible conditions. Solution methods based on combination of Type I and Type II approaches are also suggested and compared.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2393-2405
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• 2015

This paper considers a decentralized multiple faults detection and isolation (FDI) scheme for reconfigurable manipulators. Inspired by their modularization property, a global sliding mode (GSM) based stable adaptive fuzzy decentralized controller is investigated for the system in fault free, while for the system suffering from multiple faults (actuator fault and sensor fault), the decentralized sliding mode observer (DSMO) is employed to detect their occurrence. Hereafter, the time and location of faults can be determined by a fault isolation scheme via a bank of DSMOs. Finally, the effectiveness of the proposed schemes in controlling, detecting and isolating faults is illustrated by the simulations of two 3-DOF reconfigurable manipulators with different configurations successfully.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.196-202
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• 1999

Recent trend changes a criterion for evaluation of burner that environmental problem is raised as global issue. For efficient driving problem, the higher thermal efficiency and the lower oxygen in exhaust gas, burner is evaluated the better. For environmental problem, burner must satisfy $NO_{X}$ limit and CO limit. Consequently, 'good burner' means on whose thermal efficiency is high under the constraint of $NO_{X}$ and CO consistency. To make existing burner satisfy recent criterion, it is highly recommended to develop feedback control scheme whose output is the consistency of $NO_{X}$ and CO. This paper describes development of real time flame diagnosis technique that evaluate and diagnose combustion state such as consistency of components in exhaust gas, stability of flame in quantitative sense. This study focuses on wave length of luminescence from chemical reaction measurement of the luminescence via optical measuring apparatus and derive correlation with consistency of components in exhaust gas by image processing technique.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.713-716
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• 2007

Interests have been focused to the renewable energy because energy cost of fossil fuel increased and global climate change caused by CO2 evolution became severe. To overcome these problems, it is essential to develop the energy conversion technologies of renewable resources. Therefore, production and utilization state of wood and woody waste was firstly investigated and then various technologies (pyrolysis, gasification, and combustion) converting the wood and woody waste to energy were summarized. Some case studies of woody waste utilization in europe was introduced with the policy of EU countries. Economical aspect of woody waste was compared with the current fossil fuels and the energy policy of wood and woody waste was suggested.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.201-210
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• 2000

The worldwide economy has been changing to global and it's going to be put together as one market day by day. In addition the issue of industry has been advanced to automatic and unmanned systems by integration. Thus it is absolutely necessary to be develope and possess high-end technologies to survive in an age of unlimited competition. This development is the core technology of ship unmanned operating system that is very useful and applicable in many fields in addition to ship equipments. Thus it is required to design and develope our own systems which are more reliable compared with foreign products and easy to use and maintenance. We will make an progress of international competitive and contribute to the state economy.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.127-127
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• 2013

The quest for renewable energy requires us to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels. The ever-increasing demand to diversify the energy portfolio and to minimize environmental impact while supplying global energy needs, has intensified the urgency for developing alternative energy sources and carriers. Significant research efforts are under way and will continue in a broad range of materials synthesis, use-inspired and fundamental science with the use of light sources such as synchrotron and free electron lasers. Energy-related materials research faces urgent challenges today. We need to go beyond the Edisonian hit and trial approach to more systematic research with the use of advanced tools applicable under realistic in-situ and in-operando conditions capable of exploring electronic and atomic structure of catalysts and energy relevant materials. Through various scientific examples, I will explain the current state-of-the art and future directions in the aforementioned areas of research.

• IE interfaces
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• v.11 no.3
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• pp.219-225
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• 1998

Presented in this paper is a state-of-the-art review of VM(Virtual Manufacturing). To survive on a global competition, manufacturers must shorten the time to market for their products. To achieve this goal, many manufacturers have implmented CIM systems. VM is a new direction in the CIM system development having emphasis on enhancing the decision-making capability. VM can be defined an integrated, synthetic manufacturing environment exercised to enhance all levels of decision and control. Also, VM is the use of computer models and simulations of manufacturing processes to aid in the design and production of manufactured products. Currently, VP(Virtual Prototyping) and VF(Virtual Factory) are main theme to develop a VM. In this paper, the concept and current status of VP and VF are explained.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1586-1592
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• 2017

Voltage sourced converter (VSC) based direct-current (DC) grid has the ability to control power flow flexibly and securely, thus it has become one of the most valid approaches in aspect of large-scale renewable power generation, oceanic island power supply and new urban grid construction. To solve the optimal power flow (OPF) problem in DC grid, an adaptive particle swarm optimization (PSO) algorithm based on fuzzy control theory is proposed in this paper, and the optimal operation considering both power loss and voltage quality is realized. Firstly, the fuzzy membership curve is used to transform two objectives into one, the fitness value of latest step is introduced as input of fuzzy controller to adjust the controlling parameters of PSO dynamically. The proposed strategy was applied in solving the power flow issue in six terminals DC grid model, and corresponding results are presented to verify the effectiveness and feasibility of proposed algorithm.