• 대한환경공학회지
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• 제27권10호
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• pp.1065-1071
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• 2005

유체의 파속과 파형을 이용한 많은 누수탐지 기술들이 연구되고 있다. 본 연구에서는 파속을 계산하기 위해 천이류 방법을 이용하였고 누수지점의 탐지를 위해 주파수 분석방법을 개발하였다. 가압관망의 자료획득 시스템을 개발하였으며, 이를 통해 고주파 수압자료를 획득하였다. 이들 방법론은 측정과 모의 과정에서 발생되는 오차로 인한 불화실성을 적절히 처리할 수 있으며, 수압자료의 측정간을 근거로 누수의 예측지점을 추정할 수 있다. 본 연구에서 개발된 방법은 수압자료로부터 확보되는 정보를 기반으로, 누수가 동반된 천이현상에서 누수예측능력을 보여주고 있다.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2002년도 춘계 국제 학술대회
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• pp.33-36
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• 2002

This study was performed to investigate vibration generated from machines that were used at factories and construction works. Vibrations were measured at three points in a straight line based on distance from the vibration sources, and analyzed to assess the vibration levels. The average vibration level of factory machines was 65.4 dBV at 2 m, and that of construction machines was 74.0 dBV at 5m. Vibration attenuations was 4.0∼8.2 dBV by double distance. All such data were applied to gain coefficients of attenuation equations for predicting vibration level by distances from the vibration sources. Data recorded on tapes were analyzed to understand the characteristics of frequency because these characteristics are important factors to design a plan for installing the vibration-proof devices. Finally, considering results from these analysis, assessment, and prediction, the methods for reducing vibration generated from machines were discussed.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.483-486
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• 2006

The study describes the monitoring of the Bay of Bengal as a ballast water exchangeable sea using MODIS/Aqua-derived diffuse attenuation coefficient (K(490)) synchronized with in situ ballast water sampling and analysis along the LNG carrier's route between Japan and Qatar from 2002 to 2005. Based on the relationship between K(490) and corresponding in situ plankton cell densities, the Bay of Bengal is recognized as a ballast water exchangeable sea to meet the regulation of ballast water performance standard of International Maritime Organization (IMO). Furthermore the Bay of Bengal with more than 200m depth and more than 200 nautical mile distance from shore is extracted based on the regulation of ballast water exchange area of IMO. However, an anomalously high K(490) area is found off the coast of Sri Lanka during the northeast monsoon in 2005, which corresponds higher cell densities than the criterion set by the regulation of IMO. The phenomenon of high cell density in the Bay of Bengal seems to be related with the phytoplankton bloom during the northeast monsoon. Seasonal and annual variability of phytoplankton bloom will be investigated to establish an early routing system for avoiding the high cell density area in advance.

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.147-152
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• 2008

This paper has been fabricated the two different type of variable attenuators using a characteristics of a 3 dB directional coupler and pin diodes. One was not analyzed using the conventional even-odd modes but used simple two-port techniques. The resulting scattering parameters described operation characteristics for the general case where the terminating impedances are equal and unequal. After analyzing resistor role of the ${\pi}$ type fixed attenuator. this paper used a pin diode instead of a resistor. The variable attenuators were fabricated using pin diodes for current-controlled attenuation on the coupled ports of a 3 dB branch-line coupler and ${\pi}$ type fixed attenuator. The realized variable attenuators have more than 33 dB attenuation ranges at 2.1 GHz. and the input and output reflection coefficients are less than -13 dB. These results could be applied to mobile communication systems. It can be varied gain of the power amplifier according to change a outdoor environmental temperature and improved linearity.

• 한국수산과학회지
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• 제37권4호
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• pp.312-322
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• 2004

Physical and geoacoustic properties of inner shelf sediment in the South and Southeastern Seas of Korea have been studied based on six piston core samples. The sediments are largely composed of homogeneous mud except the core from the southeasternmost part of the area. Both physical and geoacoustic properties and mean grain size are relatively uniform with sediment depth, suggesting little effect of sediment compaction and/or consolidation. Mean grain size appears to be the most Important variable to determine the physical and acoustic properties. In contrast, the attenuation shows more or less fluctuations. Correlations between physical properties and sediment texture show slight deviations from those of the compared data, caused by the difference of sedimentary processes, mineral composition, and the difference of measurement system. In particular, the velocity is lower (approximately 20-30 m/s) than that of the previous data measured in the same area. This is probably due to the difference in velocity measurement system (particularly, error by a length of sample). We propose new relationships for physical and geoacoustic characteristics of shelf sediment in the study area.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2419-2431
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• 2023

Experiments related to Boron Neutron Capture Therapy (BNCT) accomplished at the Institute of Nuclear Techniques (INT), Budapest University of Technology and Economics (TUB) are presented. Relevant investigations are required before designing BNCT for vivo applications. Samples of relevant boron compounds (H₃BO₃, BDTPA) usually employed in BNCT were investigated with neutron beam. Channel #5 in the research reactor (100 kW) of INT-TUB provides the neutron beam. Boron samples are mounted on a carrier for neutron irradiation. The particle attenuation of several carrier materials was investigated, and the one with the lowest attenuation was selected. The effects of boron compound type, mass, and compound phase state were also investigated. To detect the emitted charged particles, a traditional ZnS(Ag) detector was employed. The neutron beam's interaction with the detector-detecting layer is investigated. Graphite (as a moderator) was employed to change the neutron beam's characteristics. The fast neutron beam was also thermalized by placing a portable fast neutron source in a paraffin container and irradiating the H₃BO₃. The obtained results suggest that the direct measurement approach appears to be insufficiently sensitive for determining the radiation dose committed by the Alpha particles from the ¹⁰B (n,α) reaction. As a result, a new approach must be used.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
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• pp.43-48
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• 2004

A pilot-scale system of 20t/h for the treatment of ship's ballast water and the setup of dissolved hydroxyl radical was introduced in this paper. With this experimental system, the kill efficiencies of bacteria, mono-algae, protozoan reach 100% within 2.67s when dissolved OHㆍconcentration is 0.6mg/L. At the same time, the effect of hydroxyl radicals on the photosynthesis pigments of phytoplankton was done. The results indicate that the contents of chi-a, chl-b, chl-c and carotenoid are decreased to 35~64% within 8.0s further to the lowest limit of test after 5 minutes. When dissolved OHㆍratio concentration is 0.68mg/L, the attenuation efficiencies of photosynthesis pigment are 100%. Therefore the invasive marine species can be killed in the process of the inputting and discharge ship's ballast water.

• 대한환경공학회지
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• 제22권2호
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• pp.385-399
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• 2000

매립지 침출수에 의한 지하수의 오염은 유입 오염물질 및 대수층의 특성에 의해 다양한 대수층의 환경변화를 유발하게 되며, 이러한 대수층 내의 환경변화는 유입 오염물질의 자연정화 현상에 많은 기여를 하는 것으로 알려지고 있다. 이러한 오염에 의한 대수층의 환경변화에 대한 이해는 지하수 오염의 정도와 위해성 평가, 그리고 적적한 복원 및 정화기법의 개발, 선정 및 정화 수준의 결정을 위해 필수적이다. 본고에서는 매립지 침출수에 의한 지하수 오염으로 발생하는 대수층 내의 환경변화, 즉 다양한 산화-환원대(redox zones)가 형성되는 현상과, 각 산화-환원대에서 발생하는 오염물질 저감 현상에 대한 연구 현황에 대해 정리함으로써 현재 전국적으로 산재되어 있는 많은 불량매립지의 오염 복원 및 정화를 위한 적절한 연구 및 대책 방안에 대해 제시하고 있다.

• 한국가스학회지
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• 제15권3호
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• pp.58-66
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• 2011

본 연구에서는 건설 현장에 매설된 삼중관이 항타 진동에 노출되었을 경우에 발생하는 동적 거동을 분석하였다. 항타 에너지는 7tonf의 램이 1.2m에서 낙하하였을 경우로 선정하였으며 이격 거리는 5∼30m로 변화하여 연구를 진행 하였다. 관의 길이 방향 중심에서의 진동 속도와 응력을 확인 하였고, 감쇠비를 고려하여 삼중관의 거동을 분석하였다. 매설 심도가 동일한 경우의 진동 속도에 대한 감쇠율은 이격 거리가 증가함에 따라 감소하는 추세를 보이며 내관에서 역시 이격 거리가 증가함에 따라 감소하는 추세를 보인다. 상하부에서 최대 응력값을 보이는 내관과 달리 외관은 불규칙한 응력 분포를 나타내는 것을 확인하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2005년도 공동학술대회 논문집
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• pp.37-42
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• 2005

한반도 남부 지각에서의 지진파 감쇠 양상을 나타내는 Q값을 구하기 위해 한국지질자원연구원(KIGAM)과 기상청(KMA)의 지진파 자료 중 진앙거리가 100km 이내이고 Sampling 비가 80Hz 이상인 NS방향의 540개 자료를 분석하였다. 각각의 자료에 대해 단일 산란 모델을 적용하여, S파 주시의 두 배부터 20초 길이를 가지는 시간창 위에서 1Hz, 1.5Hz, 3Hz, 6Hz, 9Hz, 12Hz, 15Hz, 18Hz의 주파수 별 coda Q 값을 구하였다. 이렇게 구한 각각의 coda Q, 즉 $Q_c$값으로부터 주파수 관계식(f> 1Hz 일 때 $Q_c=Q_{0}f^n$)을 이용하여 1Hz 에서의 coda Q, $Q_0$를 구하였다. 한반도의 $Q_0$값은 50과 250사이 그리고 n 값은 0.5 와 1.0 사이에 있고 그 지역적 분포는 반도 내 지질구조와 잘 연관됨이 밝혀졌다. 또한 반도 서해부근의 Q 값은 중국 동쪽의 값과 잘 연결되는 것을 볼 수 있었다.