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이도근,옥승용 한국안전학회 2020 한국안전학회지 Vol.35 No.3
In comparison with the existing static reliability analysis methods, the dynamic reliability analysis(DyRA) method is more suitable for estimating the failure probability of a structure subjected to earthquake excitations because it can take into account the frequency characteristics and damping capacity of the structure. However, the DyRA is known to have an issue of numerical stability due to the uncertainty in random sampling of the earthquake excitations. In order to solve this numerical stability issue in the DyRA approach, this study proposed two earthquake-scale factors. The first factor is defined as the ratio of the first earthquake excitation over the maximum value of the remaining excitations, and the second factor is defined as the condition number of the matrix consisting of the earthquake excitations. Then, we have performed parametric studies of two factors on numerical stability of the DyRA method. In illustrative example, it was clearly confirmed that the two factors can be used to verify the numerical stability of the proposed DyRA method. However, there exists a difference between the two factors. The first factor showed some overlapping region between the stable results and the unstable results so that it requires some additional reliability analysis to guarantee the stability of the DyRA method. On the contrary, the second factor clearly distinguished the stable and unstable results of the DyRA method without any overlapping region. Therefore, the second factor can be said to be better than the first factor as the criterion to determine whether or not the proposed DyRA method guarantees its numerical stability. In addition, the accuracy of the numerical analysis results of the proposed DyRA has been verified in comparison with those of the existing first-order reliability method(FORM), Monte Carlo simulation(MCS) method and subset simulation method(SSM). The comparative results confirmed that the proposed DyRA method can provide accurate and reliable estimation of the structural failure probability while maintaining the superior numerical efficiency over the existing methods
지진하중을 받는 단자유도 구조물의 신속한 동적 신뢰성 추정 방법
이도근,옥승용 한국안전학회 2020 한국안전학회지 Vol.35 No.5
This study proposes a fast estimation method of dynamic reliability indices or failure probability for SDOF structure subjected to earthquake excitations. The proposed estimation method attempts to derive coefficient function for correcting dynamic effects from static reliability analysis in order to estimate the dynamic reliability analysis results. For this purpose, a total of 60 cases of structures with various characteristics of natural frequency and damping ratio under various allowable limits were taken into account, and various types of approximation coefficient functions were considered as potential candidate models for dynamic effect correction. Each reliability index was computed by directly performing static and dynamic reliability analyses for the given 60 cases, and nonlinear curve fittings for potential candidate models were performed from the computed reliability index data. Then, the optimal estimation model was determined by evaluating the accuracy of the dynamic reliability analysis results estimated from each candidate model. Additional static and dynamic reliability analyses were performed for new models with different characteristics of natural frequency, damping ratio and allowable limit. From these results, the accuracy and numerical efficiency of the optimal estimation model were compared with the dynamic reliability analysis results. As a result, it was confirmed that the proposed model can be a very efficient tool of the dynamic reliability estimation for seismically excited SDOF structure since it can provide very fast and accurate reliability analysis results.
이도근,박지은,김미주,김현중,김해영 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.4
As of 2020, 11 GM canola events have beenauthorized as food for humans in Korea. However, thereare no simultaneous multiplex detection methods for 3 GMcanola events (DP-073496-4, MON88302, and MS11). Thus, we established the multiplex polymerase chainreaction (PCR) method coupled with capillary electrophoresisto detect 3 GM canola events. To verify thespecificity of event-specific primers, various GM crops of 3GM soybean events, 6 GM maize events, 2 GM cottonevents and 11 GM canola events were prepared. The limitof detection of the developed multiplex PCR was approximately0.0125% for 3 GM canola events. Certified GMcanola and stacked events were analyzed to validate thedeveloped multiplex PCR. This study focuses on establishingmultiplex PCR coupled with capillary electrophoresisfor newly approved GM canola events andcontributes to efficient monitoring GM canola samples inKorea.
이도근,이경찬,이치동,신경준 한국건설순환자원학회 2019 한국건설순환자원학회 논문집 Vol.7 No.4
Drying shrinkage in the hardened cement is known to change in volume by decreasing the moisture content in the hardened body, and it is known that the higher the W / C and the higher the content of the paste, the larger the drying shrinkage. In the case of ECC, more drying shrinkage occurs compared to concrete, since it does not contain coarse aggregate. Since ECC is an important material for tensile performance, the effect of restrained tensile stress on mechanical tensile behavior should be considered. The purpose of this study is to analyze the effect of stress caused by restraint on the tensile behavior of ECC. The mechanical properties of the specimens were tested by uniaxial tension tests with different restraints. As a result, the difference of tensile behavior according to restraint stress was observed and the cause was analyzed.
콘크리트표준시방서에 따른 콘크리트의 염해 내구성 설계 도표
이도근,신경준 한국콘크리트학회 2017 콘크리트학회논문집 Vol.29 No.6
해안에 인접한 지역의 콘크리트 구조물은 염해에 의하여 내구성능의 저하가 발생할 수 있기 때문에 구조물의 설계단계에서 소요의 피복두께를 확보하거나 염해저항성이 우수한 재료를 사용해야 하는 등 염해에 대한 내구성능을 확보하기 위한설계를 하여야 한다. 이러한 염해 내구성 설계는 일련의 복잡한 계산을 필요로 하거나, 관련 소프트웨어로 해석을 수행하기 때문에 일반 설계 기술자들이 쉽게 접근하기에는 어려움이 있다. 본 논문에서는 콘크리트표준시방서와 기존의 염해 내구성 설계 절차를 분석하여, 설계도표를 제안하였다. 구조물의 환경 조건과 노출 조건 등의 고정 설계변수를 결정하면, 그에 따라 내구성능을확보하기 위해 요구되는 피복두께 및 확산계수를 결정하여 설계에 활용할 수 있도록 하였다.