• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1479_1480
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• 2009

부분방전시험은 고전압 고정자 권선의 절연상태를 검사, 평가 할 수 있는 중요한 수단이다. 전동기와 발전기에서 일어나는 절연 악화의 징후로써 부분방전이 발생되며 이러한 부분방전 결함의 정확한 위치 확인이 필요하다. 본 논문에서는 회전기 고정자권선의 결함위치를 판정하기위한 Prototype의 코로나 프로브를 설계하고자 Ferrite core를 이용한 Corona Probe를 제작하였으며 모의 결함을 가지는 6.6[kV] 회전기 고정자권선에 적용하여 부분방전펄스를 측정 하였으며 설계된 Probe의 신뢰성을 확인하고자 상용 HFCT센서와 PPM97(Corona Probe)센서를 통하여 검출감도를 비교분석하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.19-22
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• 2009

Design and performance evaluation of $H_2O_2$ monopropellant thrusters to be used at attitude control of space launch vehicles were presented in this paper. Flight model thrusters were designed after two reactors for 100, 250 Newton were conformed at engineering model. Each thruster was evaluated by measurement of characteristic velocity, thrust, specific impulse, and pulse response times.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5B
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• pp.632-638
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• 2001

본 논문에서는 AMR(Adaptive Multi-Rate)를 이용하여 광대역 음성부호화기를 설계하였다. 16kHz로 샘플링된 입력 신호를 QMF 필터에 의해 두 개의 대역으로 나누어, 각각 decimation하여 두 개의 8kHz 샘플링 신호로 변환시킨 후 저대역(0Hz-3400Hz)의 신호와 고대역(3400Hz∼7000Hz)의 신호로 나누어 각각 부호화한다. 나누어진 두 개의 협대역 음성신호는 AMR(Adaptive Multi-Rate)과 ATC(Adaptive Transform Coding)을 사용하여 각각 부호화되어 전송된다. 두 대역으로부터 부호화된 정보는 20.2kbps에서 12.75kbps까지의 전송률을 갖고, 수신단에서는 각 대역을 AMR과 ATC 방법으로 역부호화하여 음성신호를 합성한다. 설계된 광대역 음성부호화기의 성능을 평가하기 위해 ITU-T의 표준안인 G.722를 포함하여 MOS 시험을 하였다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.93-95
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• 2019

본 논문에서는 높은 스위칭 주파수에서의 SiC HEMT의 병렬 운전을 다룬다. 이를 위해 300 V/600 A SiC HEMT을 이용한 병렬 풀브릿지 시스템을 설계하고 검증한다. 병렬 운전시 발생하는 전류 불균형을 제한하기 위해 병렬 소자간 인덕턴스를 설계한다. 또한 최대 순시 손실을 계산하여 이를 방열할 수 있는 냉각 시스템을 구성한다. 더블 펄스 시험을 통해 설계된 시스템의 동적(dynamic) 전류 균형과 정적(static) 전류 균형을 평가한다. 60 kHz 스위칭 주파수에서의 500 Hz 600 A 교류 제어 실험을 통해 제어 성능과 순시 손실을 검증한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2015.07a
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• pp.103-106
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• 2015

본 논문에서는 비상전원 기능을 가지는 가정용 3kW 스마트그리드 홈 에너지 시스템을 관리하는 에너지 모니터링 시스템 설계 및 구현을 제안한다. 제안하는 시스템은 3kW 스마트그리드 홈 에너지 시스템으로 인터넷을 통해 전력 정보를 수집하고, 수집된 전력 정보를 효율적으로 사용하기 위해서 모니터링과 스케줄러를 통한 관리하는 방법에 대한 설계 및 구현하고, 시험 및 평가를 통해서 에너지 절감을 확인할 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.561-564
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• 2009

This paper present design and implementation of U-city infrared image surveillance system based on the digital media processor. The hardware is designed and implemented by using commercial chips such as DM642 processor and video encoder, video decoder and the functions of software are to analyze temperature distribution of a monitoring image and to monitor disaster situation such as fire. The required functions and performances are confirmed by testing of the prototype and we verified practicality of the system.

• Journal of the Korean Geotechnical Society
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• v.35 no.8
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• pp.17-30
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• 2019

Based on pile load test results for various pile types that were constructed in-situ and pile design data of prebored PHC piles, the ratio of skin friction to total capacity (SRF) was analyzed. A SRF distribution range from the pile load test results for pilot test prebored PHC piles was 42~99% regardless of relative penetration lengths, soil types, and pile load test types. However, a SRF distribution range from the pile design data for prebored PHC piles was 20~53% regardless of relative penetration lengths and pile diameters. Also, a SRF distribution range from the restrike dynamic pile load test results for pretest working prebored PHC piles was a scattered range of 4~83% regardless of pile diameters, relative penetration lengths and soil types. The scattered SRF of pretest working piles was caused to the quality control issue on the filling of cement milk around piles and this quality control issue should be improved. The average SRF calculated by the current design method was estimated to be 2.2 times lower than the average SRF of the pilot test piles. It is because skin friction resistance is calculated at a very low level. Therefore, a new design method for skin friction will be proposed based on this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.181-186
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• 2022

Dam slope RIM is a highly important contact interface where the main body and the base surface are connected. In general, when the grouting for the slope of the dam structure is designed, it is planned using limited data (drilling, geological map, etc.). This makes it very difficult to accurately consider the original ground characteristics of the slope RIM grouting target, In addition, when the grouting volume planned during the design is drilled and injected into the original ground where the waterstop is secured, there is a possibility that the original ground with the waterstop is disturbed and the effect of the waterstop is rather diminished. In order to overcome such problems, it is more suitable to first consider geological conditions and determine whether to perform optimal grouting on the original ground through on-site repair tests before performing RIM grouting. In this paper, to determine the grouting of the RIM unit, a pilot hole water pressure test was performed on the rock of the slope in the target section. The analysis shows grouting volume of 1 Lugeon or less, and the cement injection amount also shows the injection result of 1 kg/m or less. In this case, performing grouting is rather counterproductive. This result can be evaluated through a rock of which some degree of order of mass is secured, as it is a dam design standard of 1 Lugeon or less when analyzed, using the results of visual observation and geological map creation during slope cutting. Therefore, in conclusion, it is preferable to make the decision for using RIM grouting on the slope of the dam body structure, based on 1 Lugeon in a rock state, and the cement injection amount also at 1 kg/m.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.509-523
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• 2023

The high-level nuclear waste (HLW) repository is exposed to complex environmental conditions consisting of high temperature, high humidity, and radiation, resulting in structural deterioration. Therefore, structural health monitoring is essential, and piezo sensors are used to detect cracks and estimate strength. However, since the monitoring sensors installed in the disposal tunnel and disposal container cannot be replaced or removed, the quantitative life of the monitoring sensor and its suitability must be assessed. In this study, the life of a piezo sensor for monitoring was assessed using an accelerated life test (ALT). The failure mode and mechanism of the piezo sensor under high temperature conditions were determined, and temperature stress's influence on the piezo sensor's life was analyzed. ALT was conducted on temperature stress and the relationship between temperature stress and piezo sensor life was suggested. The life of the piezo sensor was assessed using the Weibull probability distribution and the Arrhenius acceleration model. The suggested relationship can be used in multiple stress ALT designs for more precise life assessment.

• International Journal of Highway Engineering
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• v.7 no.2 s.24
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• pp.87-95
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• 2005

To prevent the lowering of structural capability due to freezing and thawing in cold winter, numerous researches on frost heaving have been performed. As the result, the freezing index contour map of the Korea peninsula has been made for the design of the anti-freezing layer of pavements. However, the validity of the anti-freezing layer needs to be evaluated because systematic investigations on the variation of freezing depth with the thickness and material types of pavement layers and the configuration of the ground have been rarely performed. The freezing index of the Korea Highway Corporation test road site was calculated and the freezing depths of the concrete and asphalt pavements of the test road were investigated using the ambient and pavement temperature and water content. In addition, the investigated freezing depths were compared to the values estimated by existing freezing depth models. This is the preliminary study on the freezing-related data measured at the test road. The results with higher reliability will be produced by the long-term accumulation of the data and the analysis on it.