• 상하수도학회지
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• 제26권3호
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• pp.361-372
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• 2012

In order to establish the methodology for estimating an emergency drinking water supply in Korea, overseas cases and accidents history of cutting off water supply were investigated, and questionnaire was conducted. Investigating accidents history of cutting off water supply in Korea, actual cutting off times of most cases were less than 13hours. Also, cases related with water quality and facility failure have been not enough to derive useful information for estimating an emergency water. From the results of questionnaire and cross-tabulation analysis, about 1,066 lpcd(liter per capita${\cdot}$day) as an emergency water and 14 days as tolerable outages time could be estimated. The results of water quality simulation could tell us that it might take 5-16 days for pollutant matter to travel from 15 contamination points to source water intake point in the selected reservoir(D-dam). This travel time was in good accordance with the estimated tolerable outage time, 14days.

• 한국전기전자재료학회논문지
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• 제33권3호
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• pp.177-180
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• 2020

This paper focuses on the 1,200-V level reverse conducting-insulated gate bipolar transistor (RC-IGBT). The structure of the RC-IGBT has an n+ collector at the collector terminal. The breakdown voltage, V_th, V_ce-sat, and turn-off time, and the electrical characteristics of a field-stop IGBT (FS-IGBT) and RC-IGBT are compared and analyzed using simulations. Based on the results, the RC-IGBT obtained a turn-off time of 320.6 ㎲ and a breakdown voltage of 1,720 V, while the FS-IGBT obtained a turn-off time of 742.2 ㎲ and a breakdown voltage of 1,440 V. Therefore, RC-IGBTs have faster on/off transitions and a higher breakdown voltage, which can reduce the size of the element.

• 한국구조물진단유지관리공학회 논문집
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• 제4권1호
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• pp.147-155
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• 2000

Five reinforced concrete rigid frame and masonry infilled wall and cut off type masonry infilled wall were tesed during vertical and cyclic loads simultaneously. Experimental programs were accomplished to improve and evaluate the structural performance of test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility etc. Test variables are hoop reinforcement ratio, with or without masonry infilled wall, and masonry method. All the specimens were constructed in one-third scale size. Based on the test results, the following conclusions can be made. For masonry infilled wall(IFB-1), maximum horizontal capacity was increased by 1.45 time in comparision with that of rigid frame(FB-0). For cut off masonry infilled wall (IFBC-1~3), maximum horizontal capacity was increased by 1.73~1.98 time in comparision with that of rigid frame(FB-0). For cut off masonry infilled wall(IFBG-1~3), ductility was increased by 1.48~2.08 time in comparision with that of masonry infilled wall (IFB-1).

• 한국정보전자통신기술학회논문지
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• 제6권3호
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• pp.168-173
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• 2013

본 연구는 IGBT(Insulated Gate Bipolar Transistor)의 전기적 특성을 향상시키기 위해 새로운 구조의 IGBT를 제안하였다. 첫 번째 구조는 기존 IGBT 구조의 P-베이스 영역 우측 부분에 N+영역을 추가한 방법으로 기존 구조에 비해 빠른 Turn-off 시간과 낮은 전도 손실을 갖는 구조이다. 또한, 두 번째 구조는 게이트 우측 하단에 P+를 형성함으로써 Latching 전류를 향상시킨 구조이다. 시뮬레이션 결과 제안된 첫 번째 구조는 빠른 Turn-off 시간(3.4us), 낮은 순방향 전압강하(3.08V)의 특성을 보였으며, 두 번째 구조는 높은 Latching 전류(369A/?? ) 특성을 보였다. 따라서 본 논문은 제안된 두 가지의 구조를 하나로 결합한 구조로써 기존 IGBT보다 향상된 특성을 시뮬레이션을 통하여 확인하였다.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3692-3697
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• 2012

Landsat 7은 SLC의 기계적 결함으로 인해 2003년 5월 31일 이후로 SLC-off 상태에서 영상을 취득하고 있으며, 이로 인해 Landsat 7 영상을 활용하기 위해서는 추가적인 보정작업이 필요하다. 본 연구에서는 SLC-off 영상을 보정할 수 있는 Gapfill 함수를 이용하여 Landsat 7 SLC-off 영상을 보정하고, 비슷한 시기의 Landsat 5 영상과 비교하였다. 기준영상 없이 SLC-off 영상을 복원하여 보정영상을 제작함으로써 SLC-off로 인한 누락 영역의 화소가 대부분 복원되었으며, 부자연스러운 노이즈가 없는 영상을 얻을 수 있었다. 또한 보정영상의 토지피복분류를 수행하고, 기준영상을 이용한 분류결과와 비교를 통해 기준영상 없이 보정된 SLC-off 영상의 활용 가능성을 제시할 수 있었다. Landsat 7 SLC-off 보정영상은 주기적인 Landsat 영상의 취득이 어려운 여건을 개선할 수 있을 것이며, 대규모 지역의 변화탐지 및 영상분류는 물론 소규모 구름 등과 같이 국지적으로 발생한 영상 손실의 복원이 가능할 것이다.

• Corrosion Science and Technology
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• 제13권5호
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• pp.186-194
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• 2014

Establishment of adhesion strength measurement procedure for marine epoxy coatings was conducted in order to ensure reliability of the test results. It was found that (1) the increase in thickness of the substrates would induce increase of pull-off strength. Especially, the increase in adhesion strength with the substrate thickness increment was attributed to the transition of stress mode to the pure tensile mode excluding bending effect. (2) The longer curing time, the higher pull-off strength. It may be due to higher cross-linking density of the coating (3) The pull-off strength increases as coating thickness increases due to the diminishment of bending effect (4) The longer drying time after water immersion, the higher pull-off strength. It may be due to the evaporation of water molecule at the coating-substrate interface.

• 한국통신학회논문지
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• 제32권5B호
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• pp.247-256
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• 2007

본 논문에서는 무선 센서 네트워크를 위한 위치 정보의 시간차를 이용한 라우팅 프로토콜(Geo-Back)을 제안한다. Geo-Back은 기존의 위치 기반 라우팅 알고리즘과 달리 주기적인 이웃 노드들의 위치 정보 혹은 하나의 홉 내에 있는 이웃 노드들 수의 정보를 이용하지 않고, 오직 소스와 목적지 노드의 위치 정보만을 이용하며, 최적의 back-off 시간 메커니즘을 사용하여 패킷 전송을 결정한다. 빈번한 토폴로지 변화 환경 하에서, 제안하는 Geo-Back 프로토콜은 업데이트를 위한 브로드캐스트 알고리즘을 사용하지 알고 빠르게 목적지까지 전송하기 위한 최적의 다음 홉을 찾을 수 있으며, 분석 결과 밀집 환경의 무선 센서 네트워크에서 확장성과 향상된 성능을 확인 하였다.

• International Journal of Advanced Culture Technology
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• 제3권2호
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• pp.34-41
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• 2015

Bonding strength of a thermal sprayed coating is difficult to measure using a conventional pull-off test method. Scratch test is a potential alternative testing method. An adhesive and a cohesive bond strength of the coating can be measured by the pull-off test while the scratch test performed on the cross-section of the thermal sprayed coating can only demonstrate the cohesive bond strength of the coating. Nevertheless, it is still beneficial to perform the scratch testing on the cross-section of the coating for the sake of comparison thus providing an alternative to the pull-off test. The scratch test method can reduce testing time and cost in the long run due to a significant cost reduction in consumables and energy and time saving from the curing step of the glue used in the pull-off test. This research investigates the possibility of using the scratch test to measure the cohesive bond strength of Mo/NiCrBSi composite coating. The results from the pull-off test and the scratch test indicate that the cohesive bond strengths of the Mo composite coating show similar trend and that the cohesive bond strength are increased when increasing NiCrBSi content.

• 한국운동역학회지
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• 제15권3호
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• pp.9-19
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• 2005

The purpose of this study was to analyze the effects of three different types of preparatory movement(squat, countermovement and hopping) in sideward responsive propulsion movement. 7 healthy subjects performed left and right side movement task by external output signal. 3D kinematics were analyzed The results were followed First, performance time in the countermovement and hopping conditions was shorter(10-20%) than that in the squat condition. The hopping condition that is more related to pre-stretch showed excellent performance. Second, time difference between after turned on the external signal and until take off was the primary factor in performance results among movement conditions. The preparatory phase before the propulsive phase in the squat condition produced more time than that in other conditions. The hopping condition showed the most short time in both the preparatory and the propulsive phase, therefore it was advantage for performance result Third, significant difference was not found in take-off velocity among movement conditions although there was difference of the time required in the propulsive phase. The maximum acceleration in the propulsive phase was larger in order of the hopping. countermovement, and squat condition. The countermovement and hopping conditions showed high take-off velocity although the propulsive phase in those conditions was shorter than that in squat condition. The pre-stretch by preparatory countermovement was considered as the positive factor of producing power in concentric contraction. Fourth, the hopping condition produced large angular velocity of joints. In hopping condition, large amount of moment for rotation movement was revealed in relatively short time and it was considered to cause powerful joint movements. In conclusion, the hopping movement using countermovement is advantage of responsive propulsion movement. It is resulted from short duration until take off and large amount of joint moment and joint power in concentric contraction by pre-stretch.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.200-200
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• 2011

Although the cut-off probe, a precise measurement method for the electron density, is widely used in the industry, the physics on the wave spectrum of the cut-off is not understood yet, only cut-off point frequency containing the information of electron density has been analyzed well. This paper analyzes the microwave frequency spectrum of the cut-off probe to see the physics behind using both microwave field simulation (CST Microwave Studio) and simplified circuit simulation. The result shows that the circuit model well reproduces the cut-off wave spectrum especially in the low frequency regime where the wavelength of the driving frequency is larger than the characteristic length and reveals the physics of transmission characteristics with frequency as resonances between vacuum, plasma and sheath. Furthermore, by controlling the time domain in solver of the microwave simulator, the cut-off like transmission peaks above the cut-off frequency which has been believed as cavity effect is verified as chamber geometry effect. The result of this paper can be used as the basis for the improvement of cut-off probe.