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KIESSI-3D 프로그램을 이용한 대형 3차원 SSI 해석
이은행,김재민,서춘교,Lee, Eun-Haeng,Kim, Jae-Min,Seo, Choon-Gyo 한국전산구조공학회 2013 한국전산구조공학회논문집 Vol.26 No.6
단단한 암반이 아닌 지반에 건설된 구조물의 지진응답을 정확하게 평가하기 위해서는 지반-구조물 상호작용(SSI)의 영향을 고려하여야 한다. 최근에는 USNRC SRP 3.7.2와 같은 원전설계분야의 규제지침 강화로 인해 SSI 해석의 필요성이 증가되고 있다. 이 연구에서는 대형 3차원 SSI 해석에 KIESSI-3D 프로그램을 사용한 사례를 제시하고 해석시간 및 정확성에 대한 토의를 하였다. 이를 위하여 대형 3차원 구조물 예제에 대한 SSI 해석을 수행하고 해석결과와 해석시간을 ACS/SASSI 프로그램과 비교하였다. 비교결과 KIESSI-3D 프로그램과 ACS/SASSI 프로그램에 의해 구한 구조응답의 전달함수가 거의 동일함을 보여 KIESSI-3D 프로그램의 정확성을 확인할 수 있었다. 아울러 해석시간 측면에서는 다중 쓰레드를 사용한 KIESSI-3D 프로그램(8개 쓰레드)이 단일 쓰레드를 사용한 ACS/SASSI 프로그램 보다 약 30배~2000배 빠른 성능을 보였다. The soil-structure interaction(SSI) effect should be considered to accurately assess the seismic response of structure constructed on soft soil site other than the hard bedrock. Recently, the demand of SSI analysis has increased due to strengthening of the regulatory guidelines of nuclear power plant such as the USNRC SRP 3.7.2. In this study an accuracy and running time of the KIESSI-3D program for large-scale 3D SSI analysis were investigated. The seismic SSI analysis using the KIESSI-3D program was performed for several examples of large-scale three-dimensional soil-structure interaction system. The analysis results were compared with those of the ACS/SASSI program. Good agreements in transfer functions at selected locations showd that KIESSI-3D yields accurate solution for large-scale SSI problem. Moreover, it was found that running speed of the KIESSI-3D for large-scale 3D SSI analysis is much faster than that of the ACS/SASSI about 30~2000 times.
이인규,이은행,김재민,Rhee, Inkyu,Lee, Eun-Haeng,Kim, Jae-Min 한국지진공학회 2021 한국지진공학회논문집 Vol.25 No.3
A shake table test is conducted for the three-story reinforced concrete building structure using 0.28 g, 0.5 g, 0.75 g, and 1.0 g of seismic input motions based on the Gyeongju earthquake. Computational efforts are made in parallel to explore the mechanical details in the structure. For engineering practice, the elastic modulus of concrete and rebar in the dynamic analysis is reduced to 38% and 50%, respectively, to calibrate the structure's natural frequencies. The engineering approach to the reduced modulus of elasticity is believed to be due to the inability to specify the flexibility of the actual boundary conditions. This aspect may lead to disadvantages of nonlinear dynamic analysis that can distort local stress and strain relationships. The initial elastic modulus can be applied directly without the so-called engineering adjustment with infinite element models with spring and spring-dashpot boundary conditions. This has the advantage of imposing the system flexibility of the structure on the sub-boundary conditions of springs and damping devices to control its sensitivity in a serial arrangement. This can reflect the flexibility of realistic boundary conditions and the effects of system damping (such as the gap between a concrete footing and shake table, loosening of steel anchors, etc.) in scalar quantities. However, these spring and dashpot coefficients can only be coordinated based on experimental results, making it challenging to select the coefficients in-prior to perform an experimental test.
경계반력법에 의한 비선형 SSI 해석을 위한 선형 FE 해석모델 검증
이계희,홍관영,이은행,김재민,Lee, Gye Hee,Hong, Kwan Young,Lee, Eun Haeng,Kim, Jae Min 한국전산구조공학회 2014 한국전산구조공학회논문집 Vol.27 No.2
이 논문에서는 경계반력법을 이용한 비선형 지반-구조물 상호작용 해석을 위해 LS-DYNA나 MIDAS/Civil 등의 유한요소해석 프로그램과 연계하는 방법을 제시하였다. 경계반력법 적용시 유한요소프로그램에서 구조물과 지반은 선형 또는 비선형 유한요소를 이용하여 모델링하였다. 유한요소의 해석모델 외부의 무한영역으로 전달되는 탄성파를 최대한 흡수하기위해 유한요소 모델의 외측에 LS-DYNA의 경우에는 PML(Perfectly Matched Layer) 요소를, MIDAS/Civil의 경우에는 점성감쇠-스프링 요소를 적용하였다. 비선형 유한요소는 구조물영역에만 적용되는 것으로 가정하였다. 이 연구에서는 입사지진파에 의한 경계반력은 KIESSI-3D 프로그램을 이용하여 계산하였다. 선형 지반-구조물 상호작용 문제에 대해 일반적인 KIESSI-3D의 해석결과와 BRM해석결과를 비교하여 제시된 방법의 효율성을 제시하였다. 또한 수치적 비교를 통해 비선형 구조에 대해 보수적인 응답을 보이는 선형 SSI문제에 대하여 얻은 경계반력이 비선형 지반-구조물 상호작용해석에 효과적으로 적용 가능함을 알 수 있었다. In this paper, a coupling scheme for applying finite element analysis(FEA) programs, such as, LS-DYNA and MIDAS/Civil, to a nonlinear soil structure interaction analysis by the boundary reaction method(BRM) is presented. With the FEA programs, the structure and soil media are discretized by linear or nonlinear finite elements. To absorb the outgoing elastic waves to unbounded soil region as much as possible, the PML elements and viscous-spring elements are used at the outer FE boundary, in the LS-DYNA model and in MIDAS/Civil model, respectively. It is also assumed that all the nonlinear elements in the problem are limited to structural region. In this study, the boundary reaction forces for the use in the BRM are calculated using the KIESSI-3D program by solving soil-foundation interaction problem subjected to incident seismic waves. The effectiveness of the proposed approach is demonstrated with a linear SSI seismic analysis problem by comparing the BRM solution with the conventional SSI solution. Numerical comparison indicates that the BRM can effectively be applied to a nonlinear soil-structure analysis if motions at the foundation obtained by the BRM for a linear SSI problem excluding the nonlinear structure is conservative.
위장관 , 입원환자에서 Polyethylene Glycol 용액을 이용한 대장내시경 전처치 시 Bisacodyl을 병행하여 복용했을 경우의 효과 비교: 전향적 무작위 비교연구
방기배 ( Ki Bae Bang ),정은행 ( Eun Haeng Jeong ),정우신 ( Woo Shin Jeong ),채현범 ( Hyun Beom Chae ),김남희 ( Nam Hee Kim ),이태훈 ( Tae Hoon Lee ),김지연 ( Ji Yeon Kim ),정윤숙 ( Yoon Suk Jung ),박정호 ( Jung Ho Park ),손정일 ( 대한소화기학회 2014 대한소화기학회지 Vol.64 No.5
Background/Aims: Inpatient status can cause inadequate bowel preparation. The majority of previous studies regarding bowel preparation have focused on comparing the effects of different purgative regimens in outpatients. However, data on bowel preparation for inpatients are lacking. The aim of this study was to investigate whether bisacodyl plus polyethylene glycol (PEG) can improve bowel preparation in hospitalized patients. Methods: A prospective, randomized and observer-blind study was performed. A total of 196 hospitalized patients undergoing colonoscopy were randomized to receive 4 L PEG (PEG only group) or 4 L PEG+bisacodyl 10 mg (bisacodyl added group). The adequacy of bowel preparation was scored using the Ottawa bowel preparation scale. Results: One hundred and eighty-three subjects completed the study, 96 in the bisacodyl added group and 87 in the PEG only group. There were no significant differences between the bisacodyl added group and the PEG only group with respect to the score of bowel cleansing (3.59±2.81 vs. 3.82±3.03, p=0.607), quality of bowel cleansing (adequate preparation 89.6% vs. 85.1%, p=0.380), and overall adverse events (66.7% vs. 52.9%, p=0.057). However, a larger proportion of patients in the PEG only group were able to ingest the entire solution as prescribed than in the bisacodyl added group (98.9% vs. 75.0%, p<0.001). Conclusions: In hospitalized patients, the quality of bowel preparation did not differ depending on whether bisacodyl is added or not. In addition, patient compliance based on consumption of cleansing agent was better in the PEG only group. (Korean J Gastroenterol 2014,64:268-277)
면진 원전구조물의 기초 유연성을 고려한 간략 비선형 SSI 해석법
김철민 ( Kim Chul Min ),이은행 ( Lee Eun Haeng ),서춘교 ( Seo Choon Gyo ),김재민 ( Kim Jae Min ) 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.21 No.1
This paper addresses simplified method for nonlinear soil-structure interactions (SSI) analysis of base-isolated nuclear power plant (NPP) structure under incident seismic waves. The accuracy and applicability of the method are evaluated by comparing with nonlinear time history responses obtained by the boundary reaction method (BRM).