• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.12
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• pp.624-630
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• 2001

The trend of the regulations on environmental issues are getting tight. Responding to this trend new technologies such as moving electrodes, wide pitch and pulsed power supply are also introduced in the electrostatic precipitator(EP) systems. The introduction of wide pitch and moving electrodes enhances the system performance of the EPs by improving air-flow and by improving the ash reentrainment on rapping. The power supplies for the EPs developed up to date include thyristor-based dc or intermittent type, SMPS(switching mode power supply) type and the pulsed-power supply type. The use of the pulsed ones is known to improve dust-collecting efficiency of high resistivity ash and reduces back corona occurrence in the collecting plate. There are two kinds of pulsed-power supplies; one with pulsed transformers and the other with direct dc switching devices. The latter uses rotary spark gap switches or semiconductor switches. Both have the merits and demerits: the spark gap switches are simple and robust but has short life time, hence, high maintenance cost, whereas the semiconductor switches have long life time but are costly. In this study, A high voltage power supply with superimposing voltage pulse on dc source was developed for EPs. This study describes circuit topology, operating principle of the scheme, and analysis of experimental results on Dong-Hae Power Plant. The pulsed power supply consists of a variable dc power supply with ratings of 60kV, 800mA and pulse generator which is made of high voltage thyristor-diode switch strings, an LC resonant tank and a blocking inductor. The pulse generator generates variable pulse-voltage up to 70kV using a high frequency resonant inverter with a variable dc source. Two prototypes were built and tested on 250MW DongHae power plant to verify the possibility of the commercial use and the normal operation in the transient states.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.2
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• pp.7-15
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• 2017

Recently, an electricity sensor system has been installed and operated to prevent failures and accidents by identifying whether a transformer is normal in advance of failure. This electricity sensor system is able to both measure and monitor the transformer's power and voltage remotely and send information to a manager when unusual operation is discovered. However, a battery is required to operate power detection devices, and battery systems need ongoing management such as regular replacement. In addition, at a maintenance cost, occasional human resources and worker safety problems arise. Accordingly, we apply a linear electromagnetic generator using vibration energy from a transformer for an electric sensor system's drive in this research and we conduct optimal design to maximize the linear electromagnetic generator's power. We consider design variables using the provided design method from Process Integration, Automation, and Optimization (PIAnO), which is common tool from process integration and design optimization (PIDO). In addition, we analyze the experiment point from the design of the experiments using "MAXWELL," which is a common electromagnet analysis program. We then create an approximate model and conduct accuracy verification. Finally, we determine the optimal model that generates the maximum power using the proven approximate kriging model and evolutionary optimization algorithm, which we then confirm via simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1808-1818
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• 2015

Recently, the wind power has experienced great attentions and growths among many renewable energy sources. To increase the power generation performance and economic feasibility, the size of wind turbine (WT) is getting bigger and most of wind power plants are being constructed on offshore. Therefore, the maintenance cost is relatively high because boats or helicopters are needed operators to reach the WT. In order to combat this kind of problem, remote monitoring and control system for the WT is needed. In this paper, the small-scale WT monitoring and control system is implemented using wireless sensor network technologies. To do this, sensor devices are installed to measure and send the WT status and control device is installed to receive control message for specific operation. The WT is managed by control center through graphic user interface (GUI) based monitoring and control software. Also, smart device based web-program is implemented to make the remote monitoring of the WT possible even though operators are not in control room.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.1
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• pp.50-54
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• 2016

A Wireless Sensor Network (WSN) is better than a conventional network for use in construction and Operations and Maintenance (O&M) because of its lower surveillance system cost. However, effective operation of a WSN is often difficult to obtain because the surveillance targets are usually fixed inside the building or underground. Therefore, this environmental constraint should be considered in the design of the WSN plant equipment surveillance system prior to installation. This study employs simulations of WSN-based fixed facility surveillance using the TinyOS TOSSIM simulator to investigate ideal types and setups of the WSN. Simulation target protocols included LEACH and flooding and gossiping protocols. The results show that the hierarchically-structured LEACH protocol demonstrated better load-balancing and efficiency than the flatly-structured flooding and gossiping protocol.

• Korean Journal of Construction Engineering and Management
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• v.7 no.6
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• pp.141-150
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• 2006

As the law on the private sector investment in social infrastructure was amended in January of 2005, the government is aggressively promoting BTL projects but many trials and errors and problems are occurring. Especially, the Value-For-Money evaluation conducted by the responsible agencies to judge the appropriateness of the project found there was a conspicuous difference between the computed cost and the final contract sum. Accordingly, this study is aimed to grasp the problems in the current Value-For-Money evaluation and to improve it in order to proceed with BTL projects efficiently. To achieve this, through a relative comparison to the final contract sum, a clear standard for the items of Value-For-Money evaluation was presented and thus, a model that can ensure accuracy in computing the Value-For-Money was established so that a delay in negotiations can be avoided. If the Value-For-Money evaluation established in this study is used in assessing the appropriateness of unit prices for BTL projects for education facilities, a reasonable result can be expected to be drawn in selection and negotiations with contractors, and maintenance and Post-Operation-Evaluation(POE) of education facilities as well.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.116-124
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• 2012

Wind is an abundant source of natural energy which can be utilized to generate power. Wind velocity does not remain constant, and as a result the output power of wind turbine generators (WTGs) fluctuates. To reduce the fluctuation, different approaches are already being proposed, such as energy storage devices, electric double layer capacitors, flywheels, and so on. These methods are effective but require a significant extra cost to installation and maintenance. This paper proposes to reduce output power fluctuation by controlling kinetic energy of a WTG system. A MW-class pitch-regulated permanent magnet synchronous generator (PMSG) is introduced to apply a power fluctuation reducing method. The major advantage of this proposed method is that, an additional energy storage system is not required to control the power fluctuation. Additionally, the proposed method can mitigate shaft stress of a WTG system. Which is reflected in an enhanced reliability of the wind turbine. Moreover, the proposed method can be changed to the maximum power point tracking (MPPT) control method by adjusting an averaging time. The proposed power smoothing control is compared with the MPPT control method and verified by using the MATLAB SIMULINK environment.

• Journal of IKEEE
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• v.24 no.2
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• pp.392-402
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• 2020

This paper proposes a solar tracking system without photo-sensors. The system can be classified into four modules: Solar Tracking, MPPT, ESS, and Real-Time Monitoring. Nine solar panels, as a basic unit, are adopted with grid structures of different heights to reduce wind influence and to enable solar tracking without photo-sensors. The low-cost MCU implements MPPT method which generates PWM switching signal for boost converter. The unit of ESS consists of three-series and four-parallel lithium-ion batteries in order to enable monitoring for abnormalities in temperature and electrical characteristics of battery. Four MCUs used in the system consists of two AVR Atmega128, and two Raspberry PI, and they exchanges operation informations. Experimental results of the proposed system show the solar tracking performance, the possibility of on-site and remote monitoring and the convenience of maintenance based on IoT technology.

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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• pp.167-175
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• 2015

The aim of this study is to establish resident-participative primary design of integrated rural development project with master planner by setting principals of open competition and transparent decision-making about village-to-village or business-to-business unit enterprise in Onui area, Hong-seong Gun. For effective processing, software projects such as residents education and rural landscape planning are simultaneously conducted for enhancing project understanding and comprehensive development plan including related post project. Above all, competition teams for individual project were organized to establish the resident-participative primary design using survey tables of residents demand. In 6 months resident-participative processing of primary design, continuous education and visiting to advanced area are conducted in team unit. Strengthened ability of team unit can be used in management and maintenance after project development. To do this, residents with the same opinions gathered as one competition team and identified business plans such as village asset, business location, size, program, and method for land securing. Favorable decision-making process by residents who are audience in project presentation of competition team has conducted. After selecting competition teams, continuos consulting are operated for establishing operation and management for developed or remodeled facilities through repetitive education and visiting advanced area. In this process, unit project suggested by competition team are completed. Preliminary selection was conducted by experts who were entrusted by residents. After residents agreement of project main stream such as major facilities and location, final detailed cost of projects are work out. Suggested process in this study which choose the final project by residents would improve residents' voluntary participation in integrated rural development project through open competition in establishing primary design.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.95-102
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• 2014

In this paper, we propose the high speed PLC-based automatic control system for a smart LED streetlight. The proposed the automatic control system were constructed of a power line modem part and monitoring part, streetlight controller part for the high speed communication frequency band and streetlight ballasts characterization and real-time remote control using a high-speed PLC network, and it was designed to meet to lighting grades conditions of KS road lighting standards. The proposed automatic control system were easy monitoring of the power consumption using PC through to the comparison result of the existing streetlight system. As a result, it was confirmed to the possibility of efficient operation for the real-time monitoring and maintenance by induction of reasonable power consumption through to the LED streetlight state checking and remote-control. In addition, we proved to improvement of expected effects for the power cost savings, the energy efficiency, and streetlight differentiation and advanced.

• Journal of KIISE
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• v.44 no.8
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• pp.832-841
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• 2017

Bug reports are essential documents for developers to localize and fix bugs. These reports contain information regarding software bugs or failures that occur during software operation and maintenance phase. Information Retrieval-based Bug Localization (IR-BL) techniques have been proposed to reduce the time and cost it takes for developers to resolve bug reports. However, if a low-quality bug report is submitted, the performance of such techniques can be significantly degraded. To address this problem, we propose a quality prediction method that selects low-quality bug reports. This process; defines a Quality property of a Bug report as a Query (Q4BaQ) and predicts the quality of the bug reports using machine learning. We evaluated the proposed method with 3 open source projects. The results of the experiment show that the proposed method achieved an average F-measure of 87.31% and outperformed previous prediction techniques by up to 6.62% in the F-measure. Finally, a combination of the proposed method and traditional automatic query reformulation method improved the MRR and MAP by 0.9% and 1.3%, respectively.