• Journal of the Korean Institute of Gas
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• v.23 no.4
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• pp.1-9
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• 2019

Large-scale industrial boilers operating at high temperature and high pressure, have a large amount of water, and a large amount of energy is released at the time of explosion. Currently, most industrial boilers use gas fuel such as LNG and LPG, etc. and fuel exists in the same space as equipment, so there is a high possibility of secondary damage such as fire or explosion in the event of a boiler accident. Both special care and management are required to operate the very dangerous equipment that causes casualty 2.51 per accident. For boilers of a certain size or more, the Korea Energy Agency conducts inspections in accordance with the Energy Usage Rationalization Act, KS, and public notice of the Ministry of Industry, Trade and Resources. In this research, based on the results of the inspection, the hazard factorss are configured, and a questionnaire is conducted to the inspector, the equipment manager, the maintenance person, and the person in charge of the manufacturer. We analyzed the results by using AHP (Analytic Hierarchy Process). As a result of analysis, generally recognized hazard factorss are not good management, measurement failure, specification failure, water leak, leak analysis, but connection, welding, scale, and corrosion, etc. are relatively less important. It is judged that the adverse factors that are recognized to be highly important among all groups and careers are already well managed, but less important and adverse factors should be well managed to ensure that the safe usage of the boiler.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1772-1780
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• 2003

An optimal soot blowing system has been developed for an optimal operation of power utility boilers by both minimization of the use of steam and the number of soot blowers worked during soot blowing. Traditionally, the soot blowing system has been operated manually by operators. However, it causes the reduction of power and thermal performance degradation because all soot blowers installed in the plant should be worked simultaneously even there are lots of tubes those are not contaminated by slagging or fouling. Heat transfer area is divided into four groups, furnace, convection area including superheater, reheater and economizer, and air preheater in the present study. The condition of cleanness of the tubes is calculated by several parameters obtained by sensors. Then, a part of soot blowers works automatically where boiler tubes are contaminated. This system has been applied in a practical power plant. Therefore, comparison has been done between this system and manual operation and the results are discussed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.101-101
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• 2016

DLC(Diamond Like Carbon)막은 그 물성의 다양함으로 인하여 산업기계, 금형, 공구, 광학 및 수송기기의 파워셀 부품등 많은 산업분야에 활용되고 있다. 일반적으로 DLC막은 증착에 사용되는 카본의 원료에 따라 크게 두 가지로 나눌 수 있는데, 이는 탄화 수소계 가스(CxHy)를 사용하여 증착된 a-C:H(amorphous Hydro-Carbon)과 고체 카본을 사용하는 a-C(amorphous Carbon)이다. 또한 a-C 중 진공 아크 공법으로 제작된 막(ta-C : tetrahedral amorphous-Carbon)은 다이아몬드 성분인 sp3의 분률이 높아, 그 경도는 40 - 85 GPa 이상이며, 무수소화로 500도 이상의 고온에서도 그 물성의 변화가 적어 그 활용도가 높아지고 있다. 하지만 높은 경도와 더불어 막의 잔류응력이 높아 3 um 이상 후막화하는 것은 어렵다. 이는 높은 잔류응력으로 인한 막의 증착시, 막 자체가 파손되거나, 기판과 막사이의 계면 밀착력이 약하여 박리되거나, 또는 높은 밀착력으로 인하여 모재가 파손되는 등 다양한 문제를 발생한다. 본 연구에서는 이 고경도 무수소 DLC막(ta-C)의 후막화하는 방안으로 주요 코팅 변수와 잔류응력과의 관계를 에너지 관점에서 파악하고 이를 활용 잔류응력을 제어하여 할 수 있는 방법을 제시하고자 한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.339-341
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• 2009

Surge Protective Device(SPD) is installed by increasing information and communication equipments and home network equipments by individual home, and the amount of SPD used is increasing by revision industry regulations and strengthening equipotential grounding system. Parts of SPD installed in residential distribution board has ZnO varistor, voltage constraint type devices, but it is exposed to Temporary Overvoltage Characteristic. This thesis analyzes products through Thermal Stability test for SPD for general house and suggests the better method. As results of analysis, Gas Discharge Tube(GDT) to cut off from a leakage current and more than two kinds of safety devices to protect Thermal Runaway were needed.

• The Optical Journal
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• s.158
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• pp.55-57
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• 2015

여기저기서 드론이 뜨고 있다. 아마존이 날아오른 드론으로 고객의 문 앞까지 배달하는 모습은 일대 장관이었다. 이제 웬만한 방송에서 하늘 높이 오른 드론으로 내려다본 모습을 전송하는 것은 그저 일상일 뿐이다. 뿐만 아니라, 사람이 직접 닿을 수 없는 곳에서 드론으로 사람을 찾는다거나, 드론을 통해 고층건물의 안전도를 검사한다거나, 정찰을 하는 등 다양한 활용도가 돋보인다. 라스베가스의 세계가전전시회(CES)에서 바르셀로나의 모바일월드콩그레스(MWC)에서 그리고 뉴욕의 장난감전시회 에서도 드론은 스타로 부상했다. 이제 드론은 대중화와 상업적 성공의 기로에 서 있다. 이를 위해서는 기계적 성능이상으로 중요한 것이 드론과 사용자간의 상호작용을 통해 이루어내는 사용자 경험이다. 즉 드론을 얼마나 쉽고 편하고 정확하고 안전하게 조종할 수 있도록 만드는가가 차별화와 경쟁력의 시작이다. 만약 드론이 지금처럼 조종하기 어렵고 심지어 인명과 재산을 위협한다고 인식되면 산업적 잠재성은 그저 한여름 밤의 꿈으로 사그러들 수밖에 없다. 몇 가지 사례를 보자. 지난 2월 미국 Fox TV 생방송에서 Popular Science 잡지 편집장 Dave Mosher는 드론의 안전성에 관해서 말하고 있었다. 그 때 데모를 위해 날던 드론이 갑자기 균형을 잃으면서 추락하였다. 이 사고로 인해 드론이 안전하지 않을 수 있다는 인식이 퍼지게 되었다. 경미한 사고지만 심각한 위협감을 일으키기도 한다. 레이더에 탐지되지 않던 드론이 미국 백악관 앞마당에 추락한 것이 그런 예이다. 어떤 사용자는 재미삼아 드론을 구름 위까지 날려 보냈다. 그러더니 드론이 제어력을 상실하였고, 결국 추락하고 말았다. 다행히도 누군가의 머리 위로 떨어지지는 않았다.

• Design & Manufacturing
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• v.14 no.2
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• pp.34-41
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• 2020

Typical characteristics of medical device parts are that they can not be reused and there are many disposable products. Therefore, there is a need for an injection molding machine having excellent repeatability of molding conditions and a precision injection mold for mass production. Recently, the performance of an injection machine has made a remarkable evolution compared to the past. However, defects such as short-shot, flash, weld line, gas burning, warpage, and deformation, which are typical defects, still do not disappear at all. This is due to the lack of gas ventilation from the product cavities, even if the gas is smoothly vented from the sprue and runner of the mold. For this reason, the internal pressure of the cavity rises and is directly connected to the quality defects. In this study, an active gas vent system was designed to prevent defects due to trapped gas in the cavity. Since it can be easily adjustable in response to the molding conditions and the mold temperature changes, it is expected to improve productivity due to the reduction of the defective ratio.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.659-661
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• 2012

볼텍스 튜브란 압축가스의 흐름을 뜨거운 공기와 차가운 공기로 전환 시켜주는 냉각 장치이다. 본 논문에서는 볼텍스 튜브에서 발생되는 소음의 특성을 파악하고자 하였다. 1/2in 소음기와 3/8in 소음기는 소음기를 장착하지 않은 경우 보다 평균8~10dB 감소되었고, 1/4in 소음기는 약15dB정도 감소하였다. 출구를 가공한 1/2in 소음기의 소음은 소음기를 장착하지 않은 경우와 비슷하고 3/8in 소음기는 소음 감소폭이 적었다. 1/4in 소음기기의 소음은 압력이 커질수록 소음이 급격히 커지는 것을 알 수 있다. 기존의 소음기와 출구를 가공한 소음기를 비교 하였을 경우 1/2in 소음기에서는 평균 9dB정도 기존 소음기의 성능이 좋고, 3/8in 소음기에서는 평균 7.5dB정도 성능이 좋은 것을 알 수 있다. 1/4in 소음기에서는 평균 9.5dB정도 기존 소음기가 소음 감소폭이 크며 압력에 따른 소음의 감소폭이 차이가 큰 것을 알 수 있다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.9
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• pp.538-544
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• 2004

This paper presents the interruption capability of serial-hybrid type GCB (gas circuit breaker) compared with that of puffer type. First a puffer type model interrupter which has the stroke length of 80 mm has been designed and manufactured. And also, a serial-hybrid type interrupter which has the same design parameters as the puffer type interrupter except the serially arranged thermal-expansion chamber and puffer cylinder has been fabricated. Using a simplified synthetic test facility, the critical interruption capabilities of the two GCBs have been estimated. The critical di/dt, the critical dV/dt of ITRV (initial transient recovery voltage) and the minimum arcing time of the puffer type model GCB were 10.7 A/${\mu}\textrm{s}$, 5.5 kV/${\mu}\textrm{s}$, and 15.0 ms respectively. In the case of serial-hybrid type model GCB, each of the values was 16.6A/${\mu}\textrm{s}$, 11.5 kV/${\mu}\textrm{s}$ and 13.0 ms. As a conclusion of this work, it has been quantitatively confirmed that the hybrid type interrupter can obtain the sufficient interruption capability at the operating force which is so low that puffer type interrupter has not the interruption capability.

• Proceedings of the KIEE Conference
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• summer
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• pp.622-624
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• 2004

To reduce the effect of fault on power systems, like GIS and transformers, power system authorities are using various technologies to monitor and diagnose there facilities. Developing On-Line monitoring systems by using IT technology is main issue of nowadays for power system authorities. Among various monitoring and diagnosis technologies, gas sensing technologies can be most useful candidate because large power systems are using gas and oils for there insulation and analyzing density of gases that are included in the gas and oils for insulation purpose tell us what kind of reaction were arisen. In this paper, we describe on the gas sensing technology that are used for power systems monitoring and diagnosis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.12
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• pp.725-731
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• 2004

In this study, the three type hybrid interrupters according to the arrangement of the thermal expansion chamber and the puffer cylinder(they are called 'serial type', 'parallel/exchanged type', and 'parallel/separated type' respectively in this work) were designed and manufactured. This paper presents the tested results of the thermal recovery characteristics on the interrupters using a simplified synthetic test facility. The 'serial type' hybrid interrupter which is to obtain more easily the pressure rise for the thermal recovery compared with the others has the best capability in the thermal recovery characteristics. In order to investigate the stress on the operating mechanism, the distortion of the stroke wave in on-load test was examined to the stroke curve in no-load test. The biggest distortion was occurred in the 'parallel/exchanged type' hybrid interrupter. Finally, the small interruption capability on the three type interrupters was estimated by a theoretical form and the 'parallel/separated type' hybrid interrupter has the advantage of the others in the view of structure.