• Particle and aerosol research
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• v.5 no.3
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• pp.123-131
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• 2009

This paper presents simulation results of particle transport in low-pressure, low-temperature plasma environment. The size dependent transport of particles in the plasma is investigated with a two-dimensional simulation tool developed in-house for plasma chamber analysis and design. The plasma model consists of the first two and three moments of the Boltzmann equation for ion and electron fluids respectively, coupled to Poisson's equation for the self-consistent electric field. The particle transport model takes into account all important factors, such as gravitational, electrostatic, ion drag, neutral drag and Brownian forces, affecting the motion of particles in the plasma environment. The particle transport model coupled with both neutral fluid and plasma models is simulated through a Lagrangian approach tracking the individual trajectory of each particle by taking a force balance on the particle. The size dependant trap locations of particles ranging from a few nm to a few ${\mu}m$ are identified in both electropositive and electronegative plasmas. The simulation results show that particles are trapped at locations where the forces acting on them balance. While fine particles tend to be trapped in the bulk, large particles accumulate near bottom sheath boundaries and around material interfaces, such as wafer and electrode edges where a sudden change in electric field occurs. Overall, small particles form a "dome" shape around the center of the plasma reactor and are also trapped in a "ring" near the radial sheath boundaries, while larger particles accumulate only in the "ring". These simulation results are qualitatively in good agreement with experimental observation.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.276-278
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• 2001

In recent years, both electric utilities and end users have expressed their deep concerns about the quality of electric power. Especially, voltage sag which is one of power quality disturbance is very serious power quality problem on the power system. Voltage sag is a decrease to between 0.1 and 0.9 pu in rms voltage magnitude on the power system for durations from 0.5 cycles to 1 minute. These voltage sags are usually caused by fault conditions, overloads, and starting of large motors. The wavelet transform has attracted considerable attention in the field of power quality analysis recently. It has proved to be a powerful tool to study those transients that have time-localized information. In this paper, different types of voltage sags are simulated by using EMTP. This paper proposes the effective technique for voltage sag detection using wavelet transform.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1180-1185
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• 2009

In this paper, the Low Pass Filter (LPF) using the equivalent circuit of T-junction microstrip line is proposed. And we derived the formulas for lumped-elements of the equivalent circuit of T-junction microstrip line to solve the frequency shift characteristic. T-junction microstrip line is de-embedded by Electromagnetic simulation tool and exact lumped element value of T-junction microstrip line is calculated by the equation of Z-parameter. We can get excellent agreement between lumped-element LPF frequency response and transmission line LPF frequency response.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.1033-1038
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• 2005

As a global effort to conservate the environment, life cycle assessment(LCA) which considers the environmental impact through the life cycle of a product, from acquiring of resources to scrapping, has been actively applied. The LCA is a tool to calculate quantitatively the environmental impacts caused by products or services through their life cycles. The list of numerous data should be analyzed, stored and conducted in order to assess the environmental impacts. Therefore, it is necessary to develop a software for LCA, which can perform the interpretation as well as the environment impact assessment to execute the analysis of such a large number of data effectively. At this time, for the existing some kinds of general LCA softwares, the information about all of input and output should be fed directly and the conclusion is deduced by linking to the database from the public authorized organizations. That makes it possible to evaluate the environmental grades accurately, but it is too slow and difficult for general users to operate and applied it into an electric motor unit(EMU). Therefore, in this research, the basic model was designed, which is based on construction of database structure of the software and organization of architecture, to develop an advanced software for EMU according to user and purpose of it by benchmarking of domestic and international softwares. The result of this study would be applied to develop the LCA software in the future.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.4
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• pp.151-155
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• 2006

HVAC transmission lines must be designed to satisfy environmental regulations. Therefore it is necessary to pre-evaluate environmental problems for transmission line designer using prediction program. In this study, environmental design software, TLCALC(Transmission Line CALCulation) for transmission lines was developed as a comprehensive window program. It has 6 modules that are audible noise, radio noise, television noise, magnetic field, electric field and conductor surface gradient. TLCALC solved a few problems in use of the existing foreign tools and took several advantages as follows; (1) It is a common tool that solves calculating limitations of foreign formulas, (2) It has wide application ranges and enhances accuracy of prediction. (3) It can be applied to almost transmission line configurations in Korea. (4) Experienced designers can get the results of calculation within about 15 minutes. Because the use of TLCALC is easy and practical, this program will be usefully applied to the environmental friendly design and construction of transmission lines. In the future, it is expected that public complaints and social environmental cost will be reduced by the use of TLCALC.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.823-825
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• 1996

This paper proposes a preventive maintenance scheduling system which is a user-friendly decision-making support system. The objective of the development of the package is to supply KEPCO's working experts with a useful tool for gaining a practical maintenance schedule. This program based on the MS Windows is made up of two main modules. The first is an interactive decision-making support module(IDSM). The main objective of this module is to provide various useful text and graphic information to users, and enable practicing engineers with sensitivity analysis of a targeting maintenance schedule. The second is a mathematical optimization module(MOM). In this module, the objective function of levelizing net reserve ratio with daily time-increment is optimized using the relaxation method.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.260-265
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• 1996

The purpose of this study was to implemented a general purpose programmable nerve stimulator system as a research tool for studying psychophysiological performance associated with various stimulation waveform. This system is composed of hardware and software, the former are the personal computer(180586) and control unit(one-chip microprocessor, D/A converter, digital output), the latter are programmed in VISUAL BASIC and ASSEMBLY Which are programmed for the programmable nerve stimuli pattern editor and communication interface, waveform preprocessing, and stimuli generator. The control unit which is entrolled by the personal computer is capable of delivering the programmable nerve stimuli waveform. This system has research potential for determining the effect of various neuromuscular blockade in alternated physiological stat is.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1501-1510
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• 2014

Low voltage direct current (LVDC) distribution system is a suitable techno-economic candidate which can create an innovative solution for distribution network development with respect to rural electrification. This research focuses on the use of LVDC distribution system to replace some of KEPCO's existing traditional medium voltage alternating current (MVAC) distribution network for rural electrification in South Korea. Considering the technical and economic risks and benefits involved in such project, a comparative techno-economic analysis on the LVDC and the MVAC distribution networks is conducted using economic assessment method such as the net present value (NPV) on a discounted cash flow (DCF) basis as well as the sensitivity analysis technique. Each would play a role in an economic performance indicator and a measure of uncertainty and risk involved in the project. In this work, a simulation model and a computational tool are concurrently developed and employed to aid the techno-economic analysis, evaluation, and estimation of the various systems efficiency and/or performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1121-1127
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• 2016

In this paper, modeling of overcurrent relay(OCR) to protect domestic AC electric railway Auto Transformer(AT) feeding system and operation characteristic analysis on overload condition are described. The target system of this paper is actual site where overload trip of circuit breaker occurs frequently. Because this AT feeding system is made of parallel single track which had a load(electric train) respectively, and is connected with only T phase of Scott Transformer. In addition, this system has been feeding 66kV voltage by KEPCO, not 154kV. We focus on protective coordination of Scott Transformer primary side and secondary side OCR for Korea single track AC electrical railway system in operation currently. We modeled single track AT feeding system and OCR. Also we performed faults and overload analysis for verification of OCR's setting values and system modeling. To analyze above mentioned research, we used PSCAD/EMTDC software tool.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.10
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• pp.1411-1417
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• 2015

The installation of PV system to the power distribution system is being increased as one of solutions for environmental pollution and energy crisis. However, the efficiency of PV system is getting decreased because of the aging phenomenon and several operation obstacles. Therefore, The technology development of aging diagnosis of PV modules are required in order to improve operation performance of PV modules. This paper proposes evaluation algorithm for aging state in PV modules by using the electrical characteristics of PV modules and environmental factors. And also, this paper presents a operation evaluation system of PV modules based on the proposed aging diagnosis algorithm of PV modules. From the simulation results of proposed evaluation system, it is confirmed that the proposed algorithm is a useful tool for aging diagnosis of PV systems.