• Title/Summary/Keyword: 장기구조성능

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A Study on Promoted High.Durability Concrete Applied to Coastal Landfill Underground Structures and long Time Monitoring (고내구성 콘크리트(PHDC)의 현장적용 성능 및 장기 모니터링에 관한 연구)

  • Kim, Woo-Jae;Kim, Do-Su;Khil, Bae-Su;Choi, Se-Jin;Hong, Seok-Beom
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.457-458
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    • 2010
  • PHDC(Promoted High Durability Concrete) is developed for preventing the chlroide attack to concrete structure on the reclaimed ground. In this study, the basic characteristics and the field application of PHDC is examined through experiments, the durability standard of the company is suggested. the long-term monitoring experiment for measuring the chloride penetration is also performed.

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A Method of Automatic Segmentation in 3-Dimensional CT image (3차원 CT 영상을 위한 자동 :Segmentation 기법)

  • Seong, Won;Kim, Jae-Pyeong;Park, Jong-Won
    • Proceedings of the Korean Information Science Society Conference
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    • 2002.04b
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    • pp.634-637
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    • 2002
  • 오늘날 CT나 MR등을 통한 의학 영상 기술과 컴퓨터 성능의 향상으로 인체 내부 장기의 영상을 비교적 용이하게 얻을 수 있으며 얻어진 영상 정보는 컴퓨터로 수치와 되므로 데이터의 조작 및 가공이 용이하다. 그러나, 이 데이터는 2D 슬라이스들의 연속으로 표현되므로 이것을 보다 편리하게 가시화. 조작, 분석이 용이한 상태로 바꾸기 위해서는 3차원 구조로의 재구성이 필요하게 된다. 이것을 위하여 무엇보다도 먼저 CT나 MR을 통하여 얻어진 영상을 분석하여 특정 장기의 영상 부분를 다른 조직의 영상부분으로부터 분리(segmentation)할 필요가 있다. 이러한 Segmentation방법에는 여러가지가 있는데, 수작업의 결합 등으로 인해서 비효율적인 문제점을 가지고 있다. 이에 본 논문은 보다 효율적인 segmentation의 처리를 위하여 region-based 기법을 응용하여 새로운 segmentation 방법을 개발하였다. 그리하여, 본 논문이 제안한 알고리즘을 슬라이스 간격이 큰 2차원 복부 CT 영상에 적용시켜 간(liver)의 추출을 시도하였고 향상된 성능을 확인할 수 있었다.

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Assessment of Reservoir Operation Module in Swat Model (SWAT 모형의 저수지 운영모듈 평가)

  • Lee, Jeong Eun;Kim, Nam Won;Kim, Hyeonjun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2020.06a
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    • pp.244-244
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    • 2020
  • 일반적으로 실제 유역에서의 계절 유출예측을 위해서는 계절 기상예측에 기반한 장기유출모델링을 수행하고 있다. 그러나, 대부분의 하천에는 하천유량의 자연적인 흐름체계에 인위적인 영향을 야기하는 댐이 건설되어 운영되고 있는 실정이다. 즉, 자연상태의 유역이 아닌 댐이 위치하고 있는 복잡한 유역에서는 반드시 저수지 운영이 고려된 유출모델링이 수행되어야 한다. 따라서, 본 연구에서는 장기유출모형의 대표적인 모형 중 하나인 SWAT의 저수지 운영모듈의 성능을 평가하고자 하였다. 한강에 위치한 다목적댐인 소양강, 충주댐을 대상으로 SWAT에 탑재되어 있는 저수지 운영모듈의 적용시 한계점을 검토하고, 이를 극복하기 위한 모듈개선을 시도하였다. 또한, 각 댐의 방류량, 저수지 수위를 중심으로 모듈개선 전후의 모의능력을 검증하였다. 저수지 운영과 관련된 모의성능은 인위적인 저류시설물이 위치하는 복잡한 유역의 유출분석시 반드시 검토되어야 하는 사항이며, 모델링을 통한 저수지 운영의 평가와 가뭄대응을 위한 비구조적 대책 수립시 매우 중요한 기능 요소이다.

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A Prediction of the Long-Term Deflection of RC Beams Externally Bonded with CFRP and GFRP (CFRP와 GFRP로 외부 부착된 철근콘크리트보의 장기 처짐 예측)

  • Kim, Sung-Hu;Kim, Kwang-Soo;Han, Kyoung-Bong;Song, Seul-Ki;Park, Sun-Kyu
    • Journal of the Korea Concrete Institute
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    • v.20 no.6
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    • pp.765-772
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    • 2008
  • For RC structures, long-term deformation occurs due to the inherent characteristics, which are creep and shrinkage. In terms of serviceability, it is important to limit deflection caused by the deformation to the allowable deflection. In the recent years, various repair and strengthening methods have been used to improve performance of the existing RC structures. One of the typical methods is FRP externally bonded method (EBR). Fiber reinforced polymer (FRP) has been used worldwide as repair and strengthening materials due to its superior properties. Besides, it has to offer improved strengthening performance not only under instantaneous load but sustained load. Therefore, accurate prediction method of deflection for the RC members externally bonded with FRP under sustained load is required. In this paper, three beams were fabricated. Two beams were externally strengthened with one of CFRP plate and GFRP plate respectively. Total three beams were superimposed under sustained load of 25 kN. During 470 days, deflections at midspan were obtained. Moreover, creep coefficients and shrinkage strains were calculated by using ACI-209 code and CEB-FIP code. In order to predict the deflection of the beams, EMM, AEMM, Branson's method and Mayer's method were used. Through the experiment, it was found that the specimen with CFRP plate has the most flexural capacity and Mayer's method is the most precise method to predict total long-term deflections.

Application of High-precision Accelerometer Made in Korea to Health Monitoring of Civil Infrastructures (국산 고정밀 가속도계의 건설 구조물 적용성 평가)

  • Kwon, Nam-Yeol;Kang, Doo-Young;Sohn, Hoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.3
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    • pp.277-283
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    • 2016
  • A high-precision force-feedback 3-axes accelerometer developed in Korea has been investigated and studied for the verification of feasibility in the computational analysis and health monitoring of civil infrastructures. Through a series of experiment, the nonlinearity, bandwidth, low-frequency signal measurement accuracy and bias characteristics of the accelerometer has been thoroughly compared to those of two accelerometers produced by two market leaders in domestic and global accelerometer market. The experiment results shows that the overall measurement performance of the accelerometer has superiority over the performance of the two accelerometers from global market leader companies. Especially, the accelerometer shows a better low-frequency signal measurement accuracy and constant bias characteristic, which are mostly required in the computational analysis and the long-term health monitoring of large-scale civil infrastructures.

A Study on the Performance Evaluation System of Conventional(ASSM) Road Tunnels (재래식(ASSM) 도로터널의 성능평가 체계 연구)

  • Park, Kwang-Rim;Chung, Jee-Seung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.27-36
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    • 2018
  • Although the current evaluation system has been revised four times since it was revised in 1996, it is insufficient to utilize it as a basis for predicting the performance degradation from the long-term viewpoint and prioritization decision for the budget input due to the evaluation system limited to securing the structural safety. Therefore, this study proposes a new evaluation system suitable for the performance evaluation of conventional (ASSM) tunnels among the various types of existing road tunnels using Delphi technique and AHP technique. Since the existing evaluation systems and evaluation items in domestic and overseas are limited in scope of evaluation criteria, the survey was conducted in conjunction with closed questionnaires on existing items and open questionnaires for eliciting new items. The validity of the questionnaire results were verified and the performance evaluation factors suitable for conventional (ASSM) tunnels were derived. After calculating weighted value of the derived evaluation item using AHP technique, a new evaluation system is proposed to meet the characteristics of the ASSM tunnel, so that they can be used as reference materials for revising and supplementing detailed guidelines of performance evaluation in the future.

Test-bed Development for Long-term Monitoring of Small Bridge Asset Management (소규모 교량 자산관리를 위한 계측 테스트베드 구축)

  • Park, Jae-Woo;Chae, Myung-Jin;Lee, Giu;Cho, Moon-Young
    • Korean Journal of Construction Engineering and Management
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    • v.13 no.6
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    • pp.13-23
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    • 2012
  • While Category 1 and Category 2 bridges are intensively inspected and carefully managed, many small bridges that are not in the Category 1 and 2 are often forgotten until they decay in serious condition. Since many of these small bridges located in the populated city, failure of them would cause huge negative impact on the community. This paper focuses on the small size concrete bridges for timely repair and rehabilitation work for the effective operation and management. Test bed is developed to define the key parameters to forecast the long term performance of the bridges, mostly concrete box bridges. Key parameters suggested in this paper are cumulative fatigue due to repetitive heavy traffic loads and the acid attacks for concrete material deterioration. The cumulative fatigue is measured by the use of the mileage concept. For the long term data collection and inspection, stable and easy to use data collection system is installed as a test bed. The contribution of this research work is on the development of the test bed to define the key parameters of bridge deterioration.

Structural Performance of Y Type Plate Connection between Circular CFT Column and H Shape Steel Beam (Y형 플레이트를 적용한 원형 CFT 기둥-H형강 보 접합부의 구조성능)

  • Jo, Hyun-Kook;Choi, Chang-Sik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.6
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    • pp.112-118
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    • 2015
  • These days, there are lots of skyscrapers being constructed in downtown areas. However, it requires columns which have a way heavier load. and far more extensive cross sections of column as well. Therefore, it is hard to lay the foundation in downtown areas. This being the case, composite columns such as CFT column are primarily being used. However, CFT column is occurred of difficult beam-column connection development and lower performance since CFT column is closed cross-section. Especially, the result of the study concerning development of connection details with CFT column and exterior diaphragms are very low in current state. In this study, through developing CFT column-H shape steel beam applicating Y shape plate, set width and depth of Y shape plate which affect structural performance of connection details applicating Y shape plate as main variables, and evaluate structural performance through experiments. And also, design Y shape plate used at experiments as setting allowable stress for tension suggested at design criteria lower than axial force of tension side flange connected Y shape plate, through shape of destruction, verify the structural safety and performance of Y shape plate.

고온 및 고온고습 가속시험에 의한 CIGS PV 모듈의 열화거동

  • Lee, Dong-Won;Nam, Song-Min;Kim, Yong-Nam
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.421-421
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    • 2012
  • Cu(In,Ga)$Se_2$ (CIGS) 화합물은 직접천이형 반도체로 열적으로 매우 안정하고 에너지밴드갭이 1.04 eV로 이상적인 값에 가깝고, 특히 높은 광흡수계수를 가지기 때문에 박막 태양전지로서 커다란 응용 잠재력을 갖고 있는 광흡수층 재료이다. CIGS 화합물 박막 태양전지의 효율은 연구실에서는 ~20%를 높은 효율을 보고하고 있으며, 모듈급에서도 ~13%의 효율을 보이고 있다. 그러나 CIGS 박막 태양전지를 대면적 또는 양산화에 적용하기 위해서는 20년 이상의 장기적인 수명을 보장할 수 있는 내구성을 갖추어야 한다. 본 연구에서는 CIGS 모듈의 장기적인 신뢰성을 평가하기 위해 CIGS PV 모듈을 대상으로 대표적인 고온 고습 조건인 IEC-61646 규격을 이용하여 $85^{\circ}C$/85% RH에서 1000시간 동안 가속시험이 수행되었고, 고온 환경하에서 모듈의 성능 저하에 미치는 영향을 고찰하기 위해 모듈을 $85^{\circ}C$에서 1000시간 노출시켰다. 두 종류의 가속 스트레스시험 후에 모듈들의 외형적인 노화현상 및 전기적 열화 성능을 분석하였다. 또한 모듈의 효율저하의 원인을 규명하기 위해 모듈 구성 재료 중 충진재료로 사용하는 EVA sheet와 투명전극 AZO를 대상으로 고장분석을 수행하였다. AZO의 미세구조 관찰, 결정상 분석, XPS 분석 및 전기적 분석과 EVA sheet의 FT-IR 분석과 TG-DSC 분석들을 종합하여 CIGS PV 모듈의 성능저하의 원인을 규명하였다.

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Techniques for Characterizing Surface Deterioration of Epoxy Exposed to Ozone Damage (오존에 노출된 에폭시 코팅재의 표면 열화특성 평가기술)

  • Choi, Sung-Min
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.3
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    • pp.167-177
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    • 2014
  • New technologies for water purification are continuously emerging to address global water quality problems, and one such technology involves advanced hermetic water purification facilities made by concrete that utilize ozone treatment processes. Better knowledge about surface deterioration of epoxy coating exposed to ozone treatment is needed as a foundation for development of improved methods and materials in the future. This study utilized atomic force microscopy (AFM), nanoindentation methods, and existing indirect methods such as visual observation, changes in mass, surface observation and chrominance analysis, to evaluate epoxy water-resistance and anti-corrosiveness. This study considered six different epoxy formulations to assess typical degradation characteristics of epoxy surfaces with regard to water-resistance/anti-corrosiveness. AFM and nanoindentation techniques emerged as promising direct methods with potential to provide quantitative measures of surface quality that are improvements upon existing indirect methods. The experiments also confirmed that some of the epoxy-coatings were severely iMPacted by ozone exposure, and thus the results demonstrate that concern about such deterioration is justified.