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Hybrid 구조물의 비선형 불안정 거동에 관한 연구(I) -초기형상 불완전에 의한 정적 면내비틀림 좌굴 특성-
김승덕,손수덕,김형석,강문명,Kim, Seung Deog,Son, Su Deok,Kim, Hyung Seok,Kang, Moon Myung 한국강구조학회 2001 韓國鋼構造學會 論文集 Vol.13 No.5
연속체 쉘을 이산화한 구조시스템은 돔형 구조물을 만들기 위해 많이 이용되고 있으며, 이러한 구조물은 하중레벨이 어느 임계값에 도달하면 구조물의 형상에 따라 뜀좌굴(snap-through) 또는 분기좌굴(bifurcation)에 의한 불안정 현상이 일어난다. 케이블 돔의 구조거동 특성은 초기장력 및 외력에 다라 비선형성이 강하게 나타나며 또한 초기조건에 매우 민감하게 반응한다. 본 연구에서는 케이블 돔의 불안정 문제를 파악하기 위해 Geiger 모델을 대상으로 하여 초기 장력도입에 의한 형상결정 문제를 다루고 이를 이용하여 완전형상 및 초기형상 불완전을 도입하여 외력에 의한 불안전성현상을 규명한다. The structural system that discreterized continuous shells is frequently used to make dome-type structures and these structures show the unstable phenomena by snap-through or bifurcation when a load level reaches certain critical value. The characteristic structural behaviour of a cable dome shows a strong nonlinearity and very sensitive according to the initial imperfection. In this study the shape finding problem by applying initial tension stress is investigated and using this the unstable phenomena of perfectly shaped and initially imperfected shape model by external forces are examined to grasp the unstable behavior of cable dome using the Geiger-type model.
스텝하중을 받는 얕은 정현형 아치의 연속 응답 스펙트럼에 의한 동적 좌굴 특성 분석
김승덕,윤태영,손수덕(KIm Seung-Deog),Yun Tae-Young,Shon Su-Deok 대한건축학회 2004 大韓建築學會論文集 : 構造系 Vol.20 No.10
Many researches have been performed for investigating dynamic instability of shell-like structures under STEP excitations, but most of them do not deal with the essential phenomenon of dynamic buckling by phase plane to investigate for occurrence of chaos. Dynamic buckling process in a phase plane is very important issue for understanding why unstable phenomena are sensitively originated in nonlinear dynamic by various initial conditions.<br/> Fundamental mechanisms of the dynamic instability are studied when the sinusoidally shaped arch structures are subjected to sinusoidally distributed excitations with pin-ends. Especially the mechanisms of dynamic indirect snapping of shallow arches are investigated under STEP function excitations. The dynamic nonlinear responses are obtained by the numerical integration of the geometrically nonlinear equation of motion.<br/> Finally, nonlinear displacement responses are obtained using Newmark - β method and the characteristics of dynamic instability are analyzed through the running response spectrum by FFT(Fast Fourier Transform)
김승덕 ( Seung Deok Kim ),정동건 ( Dong Geon Jung ),권순열 ( Soon Yeol Kwon ),최영찬 ( Young Chan Choi ),이재용 ( Jae Yong Lee ),구성모 ( Seong Mo Koo ),공성호 ( Seong Ho Kong ) 한국센서학회 2020 센서학회지 Vol.29 No.2
Total organic carbon (TOC) analysis equipment, which was previously used to prevent eutrophication in advance, is heavy, bulky, and expensive; therefore, so it is difficult to be carried and has been used as an experimental unit. In this study, a through-carbon analysis chip that integrates pretreatment through photocatalytic oxidation and carbon dioxide measurement using a pH indicator was investigated. Both the total carbon - inorganic carbon method and the nonpurgeable organic carbon (NPOC) measurement method require an acidification part for injecting an acid solution for inorganic carbon measurement and removal, an oxidation part for total carbon or NPOC oxidation and a measurement part for Carbon dioxide (CO<sub>2</sub>) measurement. Among them, the measurement of oxidation and CO<sub>2</sub> requires physical technology. The proposed TOC analysis chip decomposed into CO<sub>2</sub> as a result of the oxidizing of organic carbon using a photocatalyst, and the pH indicator that was changed by the generated CO<sub>2</sub> was optically measured. Although the area of the sample of the oxidation part and the pH indicator of the measurement part were distinguished in an enclosed space, CO<sub>2</sub> was quantified by producing an oxidation part and a measurement part that shared the same air in one chip. The proposed TOC analysis chip is less expensive and smaller, cost and size are disadvantages of existing organic carbon analysis equipment, because it does not require a separate carrier gas to transport the CO<sub>2</sub> gas in the oxidation part to the measurement part.