• Journal of Power Electronics
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• v.16 no.4
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• pp.1306-1315
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• 2016

Modern power systems driven by high-power converters have become inevitable in view of the ever increasing demand for electric power. The total power loss can be reduced by limiting the switching losses in such power converters; increased power efficiency can thus be achieved. A reduced switching frequency that is less than a few hundreds of hertz is applied to power converters that produce output waveforms with high distortion. Selective harmonic elimination pulse width modulation (SHEPWM) is an optimized low switching frequency pulse width modulation method that is based on offline estimation. This method can pre-program the harmonic profile of the output waveform over a range of modulation indices to eliminate low-order harmonics. In this paper, a SHEPWM scheme for three-phase three-leg neutral point clamped inverter is proposed. Aside from eliminating the selected harmonics, the DC capacitor voltages at the DC bus are also balanced because of the symmetrical pulse pattern over a quarter cycle of the period. The technique utilized in the estimation of switching angles involves the firefly algorithm (FA). Compared with other techniques, FA is more robust and entails less computation time. Simulation in the MATLAB/SIMULINK environment and experimental verification in the very large scale integration platform with Spartan 6A DSP are performed to prove the validity of the proposed technique.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1729-1742
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• 2017

In designing System Protection Schemes (SPSs) in power systems, protecting transmission network against extreme undesired conditions becomes a significant challenge in mitigating the transmission line overloading. This paper presents an intelligent Special Protection and Control Scheme (SPCS) using of Differential Evolution with Adaptive Mutation (DEAM) approach to obtain the optimum generation rescheduling to solve the transmission line overloading problem in system contingency conditions. DEAM algorithm employs the attraction-repulsion idea that is applied in the electromagnetism-like algorithm to support the mutation process of the conventional Differential Evolution (DE) algorithm. Different N-1 contingency conditions under base and increase load demand are considered in this paper. Simulation results have been compared with those acquired from Genetic Algorithm (GA) application. Minimum severity index has been considered as the objective function. The final results show that the presented DEAM method offers better performance than GA in terms of faster convergence and less generation fuel cost. IEEE 30-bus test system has been used to prove the effectiveness and robustness of the proposed algorithm.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.1067-1075
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• 2009

The Bimodal Tram being developed in Korea is a new transit system that provides both benefits of rail and bus systems in terms of accessibility and fixed time schedule. This study accomplished a feasibility study for introducing the Bimodal Tram system by considering the travel demand and existing transit system at a city level based on its population. The feasibility of Bimodal Tram system varies depending on cities with respect to demographic scale, mode shares, and operational distances. The strategies introduced here will help any cities where transport agencies are trying to introduce the Bimodal Tram as a new transit system.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2257-2259
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• 2004

Water Treatment Operation System is applied in most water treatment plants with DCS(Distributed Control System) or PLC(Programmable Logic Controller) system. But it has a lot of problems in viewpoint of cost and expansibilities. Therefore, we rose demand about a system that it was easier, convenient and a few costs. So, It was appeared at a Fieldbus as an alternative about this. It is used in ail industrial fields, but because of the economic reality that we can't removes the existing system, and cannot introduce new technology. Because it is actual to be hard to find an actual implementation reward and way of domestic fieldbus technology, we cannot be acknowledged with reliability in the industrial spot. Therefore, We is going to look into a fieldbus application reward in this paper. That is, We recognize structure and a kind of a fieldbus in a Chapter 2. And we is going to look into difference between a PLC method and fieldbus methods in a Chapter 3. Also, We are going to compare the system that used PLC with the system that used fieldbus (LonWorks). And the objects are JinAn and Wonju where a field bus was applied to.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2335-2341
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• 2009

High technique growth of modem times and high industrial facility in consequence of buildings demand for electric power of an extensive scale with stability supply and maintenance of high quality. But, power system always have risk of network contingency. When power system break out disturbance, it circumstantially happen like uncontrolled loss of load developing from of cascading. Severely which would be raised wide area blackout, plan to prevent, which make stability through a little of load shedding and multi-level UnderVoltageLoadShdding should work. This paper presents target, sensitivity of bus voltage have choose appropriating load shedding location and load shedding decision making logic with considering rate of change of voltage have studied multi-level under voltage load shedding scheme. Calculation of rate of change of voltage applied method of least square. As a result, we are studied an dynamic analysis of 2008 summer peak data. We have been known that network analysis is a little development and developing UnderVoltageLoadShedding scheme.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.155-164
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• 2017

PURPOSES : Owing to the growth of income and socio-economic levels, demands from road users have diversified. Accordingly, new road policies are being actively sought. The metropolitan city government of Busan has been focused on constructing and expanding roads to accommodate the increasing traffic demand. Given the increase in functional characteristics, we need to re-evaluate the hierarchy and function of roads, and specifically remodel the road planning and operations that fit into their functions. METHODS : First, this study focuses on introducing the minimum condition required to redefine the hierarchy of the roads. Second, the authors propose a new model that identifies the impact level of road hierarchy adopting discriminated analysis technique. RESULTS : Authors suggest that we redefine the hierarchy of roads in the central business distinct in Busan, and specifically the arterial roads in Busan, namely, Joonang-daero and Gaya-ro. These roads need to be reequipped with cross walks, a lower speed limit, and exclusive bus lanes to improve their accessibility. CONCLUSIONS : The authors found that the sub-arterial and collector roads have been subjected to excessive loads, owing to inappropriate functions being assigned to the main arterial road. Moreover, given that through traffic is concentrated on the sub-arterial and collector roads, over-speeding and other safety issues are consequently created.

• Land and Housing Review
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• v.11 no.2
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• pp.1-14
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• 2020

The aim of this study is to empirically identify the differentiating characteristics of determinant factors on sing-person households' commuting mode choice compared to multi-person households' one in order to establish the customized police directions to decrease private car use in commuting. While the study use the 2% sample survey data on the population and housing in 2015, it employ multinomial logit models on relative choice probability of such alternative commuting modes as bus, subway or rail, and walking, rather than driving. As potential determinant factors, the study employs demographic, socio-economic, and housing and residential one for both models of single-person and multi-person households. The study finds that the behavior of commuting mode choice has distinctive difference by gender, marriage status, physical activity constraint, job type, residential period in current housing of the single-person household's workers compared to the multi-person households' ones. Based on the findings, the study deduce ten commuting policy directions customized for the single-person household.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1805-1816
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• 2009

The Bimodal Tram being developed in Korea is a new transit system that provides both benefits of rail and bus systems in terns of accessibility and fixed time schedule. The Bimodal Tram will change the role of transit system in Korea. This study developed a strategy of introducing the Bimodal Tram system by considering the travel demand and existing transit system at a city level. The transport/transit system varies depending on cities with respect to demographic characteristics, financial capabilities, etc. The strategies introduced here will help any cities where transport agencies are trying to introduce the Bimodal Tram as a new transit system.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1936-1942
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• 2009

Shinbundang-line is new Metropolitan Railway which was invested by private capital and is under construction for opening in 2010. Now Shinbundang-line pursues various innovation, for example, an express train which uses long distance of each station, and an unmanned operation. And it may be independent of existing metropolitan railway system from a viewpoint of line and fare system. So according to the present plan, Shinbundang-line will be not able to get sufficient demand because of weak connection with existing lines and monotonous function of the line. And it may be difficult to deliver various innovation which Shinbundang-line prepares to passengers. Hereupon, in this paper, I propose 3 methods for increasing competitive power of Shinbundang-line railway. First, making Shinbundang-line a trunk railway line of southern metropolitan area was proposed in relation to northern and southern extension of it. In addition connection with bus and light rail was discussed. Second, multipurpose usage of Shinbundang-line was proposed as express train and conventional passenger train in that line in addition to simple metropolitan railway. Finally, an effective operation method which Shinbundang-line must have was proposed from unmanned driving and fare system side. These methods can improve Shinbundang-line and then it will solve traffic congestion of southern metropolitan area effectively.

• KIEE International Transactions on Power Engineering
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• v.4A no.2
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• pp.100-105
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• 2004

Installed capacity markets in the northeast of the United States ensure that adequate generation exists to satisfy regional loss of load probability (LOLP) criterion. LOLP studies are conducted to determine the amount of capacity that is needed, but they do not consider several factors that substantially affect the calculated distribution of available capacity. These studies do not account for the fact that generation availability increases during periods of high demand and therefore prices, common-cause failures that result in multiple generation units being unavailable at the same time, and the negative correlation between load and available capacity due to temperature and humidity. A categorization of incidents in an existing bulk power reliability database is proposed to analyze the existence and frequency of independent failures and those associated with resource dynamics. Findings are augmented with other empirical findings. Monte Carlo methods are proposed to model these resource dynamics. Using the IEEE Reliability Test System as a single-bus case study, the LOLP results change substantially when these factors are considered. Better data collection is necessary to support the more comprehensive modeling of resource adequacy that is proposed. In addition, a parallel processing method is used to offset the increase in computational times required to model these dynamics.