• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.587-592
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• 2006

This paper presents expansion and contraction in accordance with temperature change of contact wire and messenger wire. The tensioning device is designed and installed to pull the contact wire and messenger wire straight at all times. Pulling a contract wire straight ensures that smooth contract is maintained between the contact wire and pantograph of an electric train, and this makes it possible to ensure a stable supply of electricity to the train. Normally, tensioning devices are installed at two positions over a distance of 1.0[km] to 1.6[km] per line. In installing the tensioning device, therefore, it is necessary to study the stroke(the range of the extension/contraction rate of the tensioning device compatible with that of the contact wire and messenger wire due to change in temperature). This paper introduces and discusses this topic.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.462-465
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• 2009

This study described the design and construction of uninterruptible power supply(UPS) system for supercomputering system. KISTI's supercomputer system is served for all 24 hours, and power be achieved in stable voltage and frequency range. We analyzed the electric power usage for 4 years, and we considered cost and stability and we contructed UPS for supercomputer system.

• Advances in nano research
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• 제4권1호
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• pp.45-50
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• 2016

Data of Raman spectroscopy from graphene and few-layer graphene (FLG) irradiated by SEM electron beam in the range of energies 0.2 -30 keV are presented. The obvious effect of damaging the nanostructures by all used beam energies for specimens placed on insulator substrates ($SiO_2$) was revealed. At the same time, no signs of structural defects were observed in the cases when FLG have been arranged on metallic substrate. A new physical mechanism of under threshold energy defect production supposing possible formation of intensive electrical charged puddles on insulator substrate surface is suggested.

• Journal of Power Electronics
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• 제17권2호
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• pp.476-489
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• 2017

Under partial shading conditions (PSCs), multiple maximums may be exhibited on the P-U curve of string inverter photovoltaic (PV) systems. Under such conditions, heuristic methods are invalid for extracting a global maximum power point (GMPP); intelligent algorithms are time-consuming; and model-based methods are complex and costly. To overcome these shortcomings, a novel hybrid MPPT (MPF-IP&O) based on a model-based peak forecasting (MPF) method and an improved perturbation and observation (IP&O) method is proposed. The MPF considers the influence of temperature and does not require solar radiation measurements. In addition, it can forecast all of the peak values of the PV string without complex computation under PSCs, and it can determine the candidate GMPP after a comparison. Hence, the MPF narrows the searching range tremendously and accelerates the convergence to the GMPP. Additionally, the IP&O with a successive approximation strategy searches for the real GMPP in the neighborhood of the candidate one, which can significantly enhance the tracking efficiency. Finally, simulation and experiment results show that the proposed method has a higher tracking speed and accuracy than the perturbation and observation (P&O) and particle swarm optimization (PSO) methods under PSCs.

• Journal of Radiation Protection and Research
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• 제22권4호
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• pp.263-272
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• 1997

방사선 작업자의 과피폭을 방지하기 위해 방사선 작업 도중 이상 사태가 발생할 경우 광 음경보가 발생한 후 이상 사태 발생 90분, 발생 30분간의 방사선량과 방사선량율 변화를 저장하고 외부 PC로 데이터를 전송한 후 사고를 분석하여 차후에 같은 유형의 방사선 사고를 사전에 예방할 수 있도록 고안된 방사선 경보장치를 개발하였다. 이 방사선 경보장치의 특징은 넓은 방사선 측정 범위(10mR/h $\sim$ 100 R/h), 방사선 준위의 기록 및 기억, PC와의 data처리 기능, 휴대성, 교정 기능에 의한 높은 정밀도(${\pm}5%$), 인지도가 높은 강력한 경보기능 채택 등이다. 개발된 방사선 경보장치의 물리적 환경 적응시험을 가장 엄격한 ANSI N42.17A의 표준 시험조건에 의거하여 온도, 습도, 진동, 전자기파 간섭 등에 관해 한국표준과학연구원에서 수행하였으며 모든 시험항목을 통과하였다.

• 한국융합학회논문지
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• 제5권3호
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• pp.23-27
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• 2014

최근에 스마트폰과 디바이스의 무선충전에 대한 관심이 높아지고 있으며, 많은 기업들이 무선충전을 개발하고 있다. 무선충전은 앞으로 모바일기기뿐만 아니라 노트북 청소기 등 거의 모든 전자제품으로 적용 범위가 확대될 것이다. 무선충전 전기자동차도 올해 본격적으로 선을 보일 예정이다. 이렇듯 무선충전은 연관시장이 무궁무진하다. 세계 10대 유망기술에 포함되어 있는 무선충전은 매년 100% 이상 급성장할 전망이라고 한다. 하지만 그에 따라 존재하는 기술적 한계점과 인체 유해성에 대한 보안위협을 분석해 안전한 환경에서 사용할 수 있도록 해야 하고 각종 제도적 보안도 마련해야 한다. 무선충전에 대한 표준화와 보안대책요구사항은 체계적이지 않다. 본 논문은 모바일기기에서 자기공진방식의 무선충전의 보안 위협과 보안요구사항을 정의해 분석하고자 한다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권9호
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• pp.516-522
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• 2000

The mechanical and electrical properties of the hot-pressed and annealed $\beta-SiC-ZrB_2$ electroconductive ceramic composites were investigated as a function of the liquid forming additives of$Al_2O_3+Y_2O_3$ Phase analysis of composites by XRD revealed $\alpha-SiC(6H) ZrB_2\; and YAG(Al_5Y_3O_{12})$ The relative density of composites were increased with increased Al2O3+Y2O3 contents. The Flexural strength showed the highest value of 390.6MPa for composites added with 20wt% Al2O3+Y2O3 additives at room temperature. Owing to crack deflection crack bridging phase transition and YAG of fracture toughness mechanism the fracture toughness showed the highest value of 6.3MPa.m1/2 for composites added with 24wt% Al2O3+Y2O3 additives at room temperature. The resistance temperature coefficient showed the value of$ 2.46\times10^{-3}\;, 2.47\times10^{-3},\; 2.52\times10^{-3}/^{\circ}C$ for composite added with 16, 20, 24wt% Al2O3+Y2O3 additives respectively. The electrical resistivity of the composites was all positive temperature coefficient resistance(PTCR) in the temperature range of $256{\circ}C\; to\; 900^{\circ}C$.

• 한국지열·수열에너지학회논문집
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• 제18권3호
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• pp.7-18
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• 2022

Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△H_TNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

• 동굴
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• 제86호
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• pp.25-30
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• 2008

동굴내 환경보존을 위해서는 동굴내 관광객 통로 안내용 전기 조명을 계속 켜고 있는 것을 유도 등이나 윙카로 교체하고, 동굴내 관광객을 위하여 설치한 전기조명을 콘센트에 센서등을 추가로 설치하여 사용한다면, 현재보다 더 많은 전기 절감을 할 수 있으며 특히 성수기보다 비수기에는 더욱 더 많은 전기 절감을 할 수 있을 것으로 예상된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.357-360
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• 2000

Ferroelectric 0.05PZN-xPZT(90/10)-(0.95-x)PZT(10/90) (x=0.65, 0.85) specimens were fabricated by the mixed-oxide method and cold-pressing method using sol-gel derived PZT(90/10) and PZT(10/90) powders. All specimens show a uniform ferroelectric grain without the presence of the pyrocholre phase. Average grain size increased with an increase in sintering temperature, the value for the x=0.65 specimen sintered at 125$0^{\circ}C$ was 14.4${\mu}{\textrm}{m}$. The dielectric constant and dielectric loss of the x=0.65 specimen sintered at 125$0^{\circ}C$ were 1247, 2.05%, respectively. All specimens showed fairly good temperature and frequency stability of dielectric constant with the range from -2$0^{\circ}C$ to 6$0^{\circ}C$ and 100Hz to 10MHz. The coercive electric field and the remanent polarization of x = 0.65 specimen sintered at 125$0^{\circ}C$ were 8.5 kV/cm and 13 $\mu$C/cm$^2$, respectively.