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구조물 동적해석을 위한 현행 내진설계기준의 입력 지반 운동 선정 조건 타당성 평가 – II 지진응답
하성진,한상환,오장현 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.4
Current seismic design provisions such as ASCE 7-10 provide criteria for selecting ground motions for conducting response history analysis. This study is the sequel of a companion paper (I – Ground Motion Selection) for assessment of the ASCE 7-10 criteria. To assess of the ASCE 7-10 criteria, nonlinear response history analyses of twelve single degree of freedom (SDF) systems and one multi-degree of freedom (MDF) system are conducted in this study. The results show that the target seismic demands for SDF can be predicted using the mean seismic demands over seven and ten ground motions selected according to the proposed method within an error of 30% and 20%, respectively
목표스펙트럼의 평균과 분산을 고려한 지반운동 선정과 배율조정계수 결정방법
하성진,박미영,한상환 한국지진공학회 2016 한국지진공학회논문집 Vol.20 No.5
It is important to select proper ground motions for obtaining accurate results from response history analyses. The purpose of this study is to propose an accurate and efficient method that does not require excessive computation for selecting and scaling ground motions to match target response spectrum mean and variance. The proposed method is conceptually simple and straightforward, and it does not use a simulation algorithm that requires a sophisticated subroutine program. In this method, the desired number of ground motions are sequentially scaled and selected from a ground motion library. The proposed method gives the best selection results using Sum of Square Error and has the smallest value(=0.14). Also, The accuracy and consistency of the proposed method are verified by comparing the selection results of the proposed method with those of existing methods.
분산제의 종류 및 사용량에 따른 CNT 보강 시멘트 복합체의 강도변화
하성진,강수태,이종한 한국구조물진단유지관리공학회 2015 한국구조물진단유지관리공학회 논문집 Vol.19 No.2
This study was aimed to investigate the difference in strength of Carbon Nanotube (CNT) reinforced cement mortars with different types of surfactants and doses. In the experimental program, CTAB, SDBS and TX10 which were common surfactants adopted to improve CNTs dispersion in fabricating CNT composites in many industrial fields were included and superplasticizer which was revealed to be effective to disperse CNTs especially in CNT reinforced cementitious composites were added as well. Superplasticizer presented less strength reduction in cement mortar and more strength gain by adding CNTs among four types of surfactants. Higher dosage of superplasticizer caused lower strength of cement mortar. Adding CNTs of 0.4 wt.% or less to cement didn’t show strength enhancement by adding CNTs but 0.8 wt.% of CNTs resulted in strengthening effect after all. Finally, a combination of 0.1 wt.% of CNTs, superplasticizer and sonication treatment could lead to strength improvement by adding CNTs in cement mortar. 이 연구는 탄소나노튜브의 우수한 역학적 특성을 시멘트재료에 활용하여 역학적인 특성을 향상시키고자 현재 탄소나노튜브를 활용하고있는 분야에서 탄소나노튜브의 분산성을 향상시키는데 사용되고 있는 계면활성제인 CTAB, SDBS, TX10 및 문헌조사를 통하여 유효하다알려진 고성능감수제와 탄소나노튜브를 혼합한 모르타르 강도 시험체를 제작하여, 계면활성제 종류에 따른 특성 및 사용량에 따른 복합체의 강도변화를 평가하였다. 계면활성제 중에서는 고성능감수제가 작은 강도저하 현상 및 CNT 보강에 따른 높은 강도향상 효과를 나타내었다. 고성능감수제의 사용량에 따른 강도변화에서는 사용량 증가에 따라 실험체의 강도는 감소하였으며, CNT 보강에 따른 강도향상 효과는시멘트 중량 대비 0.4% 이하에서는 나타나지 않으며 0.8%이상의 사용량에서 나타났다. 마지막으로 CNT의 사용량을 감소시키고 초음파로처리한 탄소나노튜브를 보강한 시험체의 경우 탄소나노튜브를 혼합하지 않은 실험체보다 강도가 증가하는 결과를 얻을 수 있었다.
점지진원 모델을 이용한 경주 지진으로 인한 지반운동 생성
하성진,지현우,한상환 한국지진공학회 2016 한국지진공학회논문집 Vol.20 No.7
In low to moderate seismic regions, there are limited earthquake ground motion data recorded from past earthquakes. In this regard, th e Gyeongju earthquake (M=5.8)occurred on September 12, 2016 produces valuable information on ground motions. Ground motions w ere recorded at various recording stations located widely in Korean peninsula. Without actual recoded ground motions, it is impossible t o make a ground motion prediction model. In this study, a point source model is constructed to accurately simulate ground motions rec orded at different stations located on different soil conditions during the Gyeongju earthquake. Using the model, ground motions are ge nerated at all grid locations of Korean peninsula. Each grid size has 0.1°(latitude)x0.1°(longitude). Then a contour hazard map is constr ucted using the peak ground acceleration of the simulated ground motions
구조물 동적해석을 위한 현행 내진설계기준의 입력 지반 운동 선정 조건 타당성 평가 – I 선정방법
하성진,한상환,지현우 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.4
For estimating the seismic demand of buildings, most seismic design provisions permit conducting linear and nonlinear response history analysis. In order to obtain reliable results from response history analyses, a proper selection of input ground motions is required. In this study, an accurate algorithm for selecting and scaling ground motions is proposed, which satisfies the ASCE 7-10 criteria. In the proposed algorithm, a desired number of ground motions are sequentially scaled and selected from a ground motion library without iterations.
세라믹 LDH 나노하이브리드를 이용한 MRI 조영제의 최신 연구동향
하성진(Seongjin Ha),김문희(Wenji Jin),박대환(Dae-Hwan Park) 한국세라믹학회 2019 세라미스트 Vol.22 No.3
Ceramic layered double hydroxide (LDH) nanohybrids have attracted considerable interest in biomedical science due to their unique structural feature and characteristics in biological condition. Many studies on LDH nanoparticles have been reported in diagnosis applications including magnetic resonance imaging (MRI) contrast agents in order to not only provide better imaging performance through multimodal imaging strategy, but realize therapeutic function which treat cancers in one platform. This review highlights the recent progress in MRI T 1 contrast agent, dual modal imaging system, and MRI-guided drug delivery systems ranging from synthetic method and characterization to evaluation in vitro and in vivo based on the ceramic LDH nanohybrids. Future research directions are also suggested for next-generation bio-imaging contrast agent.
3차원 시간이력해석을 위한 내진설계기준의 설계지진파 요구조건 타당성 평가
하성진(Ha, Seong Jin) 대한건축학회 2020 대한건축학회논문집 Vol.36 No.7
To obtain reliable results for time history analysis of structure under earthquake loads, it is required to selecting proper input ground motions and constructing numerical model for the structure. Especially, for high-rise or irregular building, structural engineers should conduct three dimensional dynamic analysis. The purpose of this study was to evaluate of seismic design criteria for selecting ground motions to conducting three dimensional time history analysis of structures. For this purpose, 134 earthquake records which are composed of two horizontal ground motions, respectively, were collected. Then, several three dimensional time history analyses for 3, 9-story steel moment resisting structures with or without irregularities. Input ground motions were selected according to KDS 41 17 00 criteria for design ground motions using proposed method from a companion paper. The results show that one can predict seismic responses of three dimensional structure within an error of 20% using more than 10 ground motions. However, if less than 7 ground motions are used, the responses may be overestimated.