• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.29-32
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• 2016

본 논문에서는 나로호(KSLV-I) 비행상태의 실시간 감시를 목적으로 국내에서는 처음 개발된 우주센터 원격수신자료전시시스템(EDS)의 구축과 운용을 소개한다. EDS는 우주센터 발사통제시스템의 주요 시스템 중 하나이고 그 역할은 위성발사체의 비행에 중대한 영향을 주는 주요정보(QLM)와 궤적정보(TSPI)를 수신하여 실시간으로 처리함으로써 탑재 서브시스템별 전문가들이 위성발사체의 비행 상태를 감시할 수 있도록 지원하는 것이다. EDS는 3회에 걸친 나로호 비행시험에서 그 역할에 따라 매회 8대가 운영되었으며 임무를 성공적으로 수행하였다. 본 시스템을 기반으로 추후 발전된 형태의 한국형발사체(KSLV-II) 비행상태의 실시간 감시시스템의 구축이 가능할 것으로 예상된다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.267-268
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• 2011

인터넷데이터센터는 현대 IT산업의 중심설비로서 수십 MW의 전력을 소비하는 집중부하형태를 취하고 있다. 인터넷데이터센터의 특성상 전원의 신뢰성을 높이기 위하여 무정전전원장치(UPS)를 사용하는 것이 필수사항이다. 따라서 기존의 교류방식은 (교류-직류), (직류-교류), (교류-직류)의 3단계 전력변환이 필요하여 전체 급전계통의 효율저하를 가져온다. 이에 비하여 직류급전방식은 기존 계통 망에 연결하기 위한 (교류-직류) 1단계의 전력변환만 필요하므로 효율을 크게 개선할 수 있을 뿐만 아니라 전원의 신뢰도를 높일 수 있다고 알려져 있다. 본 논문에서는 인터넷데이터센터 내에 220V교류방식과 300V직류방식의 시험용 급전계통을 구축하고 똑같은 부하운전 조건에서 실제의 급전효율을 측정하였다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.199-202
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• 2010

우주발사체를 운용하는 발사장은 화재나 폭발의 위험에 많이 노출 되어 있다. 발사장은 비행시험전 발사체의 모든 상태를 점검 하고, 비행시험을 수행하는 곳이다. 또, 유사시에는 대량의 산화제와 연료가 누출 되어 화재 및 폭발사고로 이어질 가능성이 있는 곳이다. 나로우주센터에서 운용하는 우주발사체 나로호는 연료로 케로신(kerosene)을 사용하고, 산화제로 액화산소(LOX)를 사용한다. 발사대의 소화설비는 화재발생시 원격제어를 통해서 소화수와 소화약제를 분사하여 진화하는 방식으로 구성 되어 있다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.72-73
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• 2019

항로표지 분야의 시장은 소규모시장으로 산업체가 영세하여 기술개발 및 투자를 기피하고 있다. 또한 장비용품을 개발하더라도 실제 환경과 유사한 환경에서 성능을 검증하는 시설도 부족한 실정이다. 해양수산부와 한국항로표지기술원에서는 산업체에서 개발한 등부표, 등명기, 충방전조절기 등의 항로표지 장비용품의 성능시험을 위한 육 해상 항로표지 성능검증 테스트베드를 구축하였다. 테스트베드에서는 성능시험 및 제품개발 단계에서부터 컨설팅, 기술지원 등을 통한 문제점을 사전에 도출하여 개선을 유도하는 등 기술지원체계를 마련하였다. 본 논문에서는 항로표지기술지원센터의 구축 및 운영에 관한 사항을 기술하였다.

• Journal of Powder Materials
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• v.27 no.6
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• pp.503-508
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• 2020

The mechanical properties and microstructures of hexagonal boron nitride (h-BN)-reinforced cement composites are experimentally studied for three and seven curing days. Various sizes (5, 10, and 18 ㎛) and concentrations (0.1%, 0.25%, 0.5%, and 1.0%) of h-BN are dispersed by the tip ultrasonication method in water and incorporated into the cement composite. The compressive strength of the h-BN reinforced cements increases by 40.9%, when 0.5 wt% of 18 ㎛-sized h-BN is added. However, the compressive strength decreases when the 1.0 wt% cement composite is added, owing to the aggregation of the h-BNs in the cement composite. The microstructural characterization of the h-BN-reinforced cement composite indicates that the h-BNs act as bridges connecting the cracks, resulting in improved mechanical properties for the reinforced cement composite.

• Journal of Powder Materials
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• v.29 no.6
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• pp.505-510
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• 2022

The thermal shock resistance of cement composites with hollow glass microspheres (HGM) is investigated. Cement composites containing various concentrations of HGM are prepared and their properties studied. The density, thermal conductivity, and coefficient of thermal expansion of the composites decrease with increasing HGM concentration. A thermal shock test is performed by cycling between -60 and 50℃. After the thermal shock test, the compressive strength of the cement composite without HGM decreases by 28.4%, whereas the compressive strength of the cement composite with 30 wt% HGM decreases by 5.7%. This confirms that the thermal shock resistance of cement is improved by the incorporation of HGM. This effect is attributed to the reduction of the thermal conductivity and coefficient of thermal expansion of the cement composite because of the incorporation of HGM, thereby reducing the occurrence of defects due to external temperature changes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.426-433
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• 2020

This study aimed to compare the pretreatment methods of phytoplankton for type approval of the Ballast Water Treatment System (BWMS). The International Maritime Organization (IMO) and the United States Maritime Police (USCG) use two different test methods for this purpose. To compare the two methods, a test for concentration and non-concentration was performed with cultured and natural phytoplankton, and samples from the land-based BWMS test. The extent of damages caused by the process of concentration varied between cultured and natural species, indicating differences depending on the physiological and morphological characteristics of the species. In the land-based test, in the control water with a high biological population, the number of non-concentrated samples was about twice as high as that of the concentrated samples. There was no distinct difference between the two methods in the treated water with a low biological population. Thus, although there is a difference between concentration and non-concentration for phytoplankton sampling, the concentration method can be applied as a method of evaluating BWMS performance. However, a method for evaluating whether live species in treated water may be lost or damaged during the concentration process of sampling should be developed and validated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.453-459
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• 2006

This paper presents an experimental evaluation of wandering effect on asphalt concrete pavement responses. A laser-based wandering system has been developed and its performance is verified under various field conditions. The portable wandering system composed of two laser sensors with Position Sensitive Devices can allow one to measure the distance between laser sensors and tire edges of moving vehicle. Therefore, lateral position of each wheel on the pavement can be determined in a real time manner. Pavement responses due to different loading paths are investigated using a roll over test which is carried out on one of asphalt surfaced pavements in the Korea Highway Corporation test road. The pavement section (A5) consists of 5 cm thick surface course; 7 cm intermediate course; and 18 mm base course, and is heavily instrumented with strain gauges, vertical soil pressure cells and thermo-couples. From the center of wheel paths, seven equally-spaced lateral loading paths are carefully selected over an 140 cm wandering zone. Test results show that lateral horizontal strains in both surface and intermediate courses are mostly compressive right under the loading path and tensile strains start to develop as the loading offset becomes 40 cm from the wheel path. The development of the vertical stresses in the top layers of subbase and anti-frost is found to be minimal once the loading offset becomes 50 cm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.5
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• pp.507-517
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• 2010

The KOREAN AIR - R&D Center has developed a solar array for STSAT-2 Flight Model, SaTReC-KAIST, using a fully localized technology and has verified the performance through a launch vibration test, orbit environment test and electrical performance test. The solar array will be launched at NARO Space Center by KSLV-I which is the first Korean launch vehicle, in May 2010. In this paper, a current-voltage curve that shows the power characteristics of solar arrays was derived by applying elements that affects the power performance of STSAT-2's solar arrays to the solar cell equivalent models. The result was compared to LAPSS test results, and accuracy of the solar cell equivalent model and the power performance simulation has been analyzed.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.439-443
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• 2011

It was performed to test the combustive properties of low density polyethylene and ethylene vinyl acetate (LDPE-EVA) mixture by the addition of magnesium hydroxide. Flame retardant of natural magnesium hydroxide was added to the mixture of LDPE-EVA in 40 to 80 wt% concentration. The composite was compounded to prepare specimen for combustive analysis by cone calorimeter (ISO 5660-1). Comparing with virgin LDPE-EVA, the specimens including the magnesium hydroxide had lower combustive properties. It is supposed that the combustion-retardation properties in the composites improved due to the endothermic decomposition of magnesium hydroxide. The specimens with magnesium hydroxide showed both the lower peak heat release rate (PHRR) and lower effective heat of combustion (EHC) than those of virgin polymer. As the magnesium hydroxide content increases, time to ignition increased and the peak heat release rate decreased.