• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1259-1261
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• 1993

Amorphous chalcogenide glasses are highly transparent in the near $1{\mu}m$ wavelength region, which corresponds to the wavelength region of the optical communication system. Optical properties of these materials, including the transmittance, the optical gap, and the shift associated with reversible photostruction change, were measured. Thereafter, optical waveguide was fabricated by the laser lithographic technique and then, guide modes were measured by utilizing the end-fire coupling technique. The field patterns of both the single mode and the multimode waveguide were observed.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.39-42
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• 2004

주변압기실에 Water Mist 소화설비의 적용을 위하여 과거 화재사례 분석, 변압기의 형태, 변압기실의 구조 등을 검토하여 3가지 화재유형을 상정하였고, 발생 가능한 화재규모 및 종류를 검토하여 소화성능 평가를 위한 6가지 화재 시나리오를 제시하고 이를 검증하기 위한 모의실험을 수행하였다. 본 연구를 통하여 주변압기실에 적용 가능한 최적의 Water Mist 소화설비의 시험기준을 정립하였으며, 향후 본 시험기준에 의한 전력공급용 주변압기실 Water Mist 소화설비가 화재에 의한 대형 재난을 예방함과 동시에 안정적인 전력공급에 이바지할 것으로 기대된다.

• Proceedings of the KIEE Conference
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• summer
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• pp.276-279
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• 2004

The purpose of this paper is to describe and demonstrate how a utility-connectable inverter for photovoltaic or fuel-cell applications can be well modeled using PSCAD/EMTDC. In this paper, a single-phase IGBT inverter using SPWM is modeled. Simple voltage magnitude and phase controls are implemented using PSCAD's Pl controller, PLL, and a 'user defined' component called Modulo (found in their extensive collection of example circuits). The circuit model also takes advantage of PSCAD's interpolated firing pulse option, which provides improved simulation results by preventing errors from being introduced when switches fire between time simulation steps. Additionally, SCAD's Online Frequency Scanner for FFT is utilized for a demonstration of PSCAD's frequency-domain analysis capabilities.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.9-11
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• 2018

This paper studies on the development of an electric fire prevention system with the detection and alarm in case of parallel arc fault occurrence in low voltage distribution lines. The proposed detector has the characteristics of high speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. The line voltage is always feedback, and when an arc or a spark occurs, these are detected by the microcomputer. In addition, we design and develop algorithms using high speed and high precision microcomputer. A new conceptual control technique is adopted that RCD cuts-off by forming a forced short circuit between the phase voltage and ground in the event of an electrical accident. Some experimental tests of the proposed system also confirm practicality and the validity of the analytical results.

• Journal of IKEEE
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• v.26 no.2
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• pp.196-204
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• 2022

Electrostatic discharge (ESD) protection devices of P-type embedded silicon-controlled rectifier (PESCR) structure were analyzed for high-voltage operating input/output (I/O) applications. Conventional PESCR standard device exhibits typical SCR characteristics with very low-snapback holding voltages, resulting in latch-up problems during normal operation. However, the modified device with the counter pocket source (CPS) surrounding N⁺ source region and partially formed P-well (PPW) structures proposed in this study could improve latch-up immunity by indicating high on-resistance and snapback holding voltage.

• Fire Science and Engineering
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• v.15 no.4
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• pp.78-85
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• 2001

This dissertation is research on the fireproof characteristic of molded transformer and the extinguishable characteristics of the NAF S-III. As the research method, a theoretical examination has been made for the combustion process of epoxy resin, which was the main material of molded transformer, and extinguishing process of NAF S-III, which has recently been used in the clean extinguishable chemicals. Furthermore, for its proof, the experiments on combustion and extin-guishment on molded transformer has been performed. By installing the actual molded transformer in and artificial the horizontal heating furnace which has similar conditions with the electrical substation, and after subsequently ignited, the extinguishing process has been observed by classifying it into the natural extinguishment of the ignited transformer, and extinguishable chemical in NAF S-III has been injected. The volume of injected extinguishable chemical was the economical amount which was equipped with the extinguishable capability on the molded transformer under combustion, and it was calculated with the Announcement of the Ministry of Government Administration and Home Affairs as the basis. With the injection of the calculated extinguishable chemicals, the ignited transformer has completely extinguished within one minute.

• Journal of Energy Engineering
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• v.15 no.3 s.47
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• pp.181-187
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• 2006

This paper is proposed to a solar cell power system used in fire emergency equipment. Also it is designed with a high efficiency power converter in order to increase efficiency of power system. The controlling switches used in DC-DC booster chopper and DC-AC inverter are operated with soft switching, which is applied to resonant circuit method to reduce switching loss. The result is that the system gets to high efficiency. In this paper, A detection circuit of maximum power point of solar cell is described in this paper. And the performance evaluations for the photovoltaic power system of high efficiency are examined by the analysis of a new tracking controller with a maximum power $P_{max}$ detection of solar cell.

• Fire Science and Engineering
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• v.18 no.4
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• pp.57-63
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• 2004

We investigated heat properties of connection terminal in residual current protective devices(RCD) according to contact pressure for low voltage appliance. And we analyzed voltage and current waveform and oxide propagation when the poor-contact happened between terminal and wire. When contact pressure between terminal and connection wire was not applied, the heat was generated and an oxide was formed on the surface of the wire. The temperature of the insulation surrounding terminal was ascended sharply by poor-contact, micro-sparks and continuous arc sound happened in interior terminal. When the poor-contact by vibration occurred inner conductor of terminal and wire, an oxide was propagated on contact surface and the temperature was increased at 869℃. Thus, we found that the risk of electrical disaster is high in terminal and connection wire parts.

• Journal of IKEEE
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• v.24 no.2
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• pp.536-542
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• 2020

This paper presents a nature-inspired wideband sprout-leaf shaped antenna with end-fire radiation pattern. A sprout-leaf shape angled-radiator was designed for wide beamwidth radiation patterns for motion detection sensors. An extended and truncated ground plane was used as a reflector for end-fire radiation patterns. To feed the balanced radiator, a broadband microstrip (MS) to coplanar stripline (CPS) balun was utilized with excellent amplitude and phase balance. The proposed antenna demonstrates wide frequency bandwidth from 8.5 to 14.5 GHz with wide beamwidth and the radiation efficiency of 90%. The measured gain is from 4 to 5 dBi and front-to-back ratio was 10 to 20 dB. It has been shown that the proposed antenna can be used for imaging sensors, phased array systems, and radars that require a wide bandwidth and a directional radiation pattern.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.15-22
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• 2011

Explosion and fire cause about 30 reported industrial major accidents a year by ignition source which discharge of electrostatic generated to flammable gas, vapor, dust and mixtures. It brings economically and humanly very large loss that accident was caused by fire and explosion from electrostatic discharge. Thus, it is very important that electrostatic discharge energy is to be control below not to be igniting flammable mixtures. There are two kinds of analysis model for electrostatic discharge, human body model and machine model. Human body model is available the parameter of human's electrical equivalent that capacitance is 100 pF, resistance is $1.5k{\Omega}$. To simulate and visualize the electrostatic discharge from human body need a very expensive and high voltage simulator. In this paper, we measured the value of capacitance and resistance concerned with test materials and sizing of specimen and the value of charged voltage concerned with test specimen and distance to develop an electrostatic charge/discharge simulating tool for teaching with which concerned industrial employee and students. The result of experiments, we conformed that the minimum ignition energy of methane-oxygen mixtures meets well the equation $W=1/2CV^2$, and found out that the insulating material and sizing of equivalent value having human body mode are the poly ethylene of 200 mm and 300 mm of diameter. Developed electrostatic charge/discharge simulating tool has many merits; simple mechanism, low cost, no need of electric power and so on.