• International Journal of Naval Architecture and Ocean Engineering
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• 제3권2호
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• pp.116-121
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• 2011

The Spectral Fatigue Analysis is representative fatigue life assessment method for vessels. This Analysis is performed generally for the whole vessel and many assessment sites. The spectral fatigue analysis is performed through the process of hydrodynamic response analysis, global structural analysis, local structural analysis and calculation of fatigue damage. In these processes, fatigue damage is affected by many variables. The representative variables are S-N curve data, wave scatter data, wave spectrum, bandwidth effect and etc. In this paper, the effects of these variables to the fatigue damage are analyzed through the spectral fatigue analysis for 170k LNGC.

• 한국지진공학회논문집
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• 제4권3호
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• pp.11-21
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• 2000

구조물에 내진설계를 적용하는 목적은 지진에 노출되는 구조물에 안전성과 경제성을 고려한 파괴메카니즘을 부여하는 것이다. 내진설계에 보편적으로 적용하고 있는 응답스펙트럼해석법은 선형해석법으로 구조물의 비선형 동적거동에 의한 영향은 특정 계수로 반영한다. 그러나 기존의 내진설계시방서들이 강진지역에 있는 나라들에 의해 제정 및 개정되어 왔기 때문에 응답스펙트럼 해석법 뿐만 아니라 기타의 적용규정이 강진지역에 위치한 구조물의 상황만을 고려하여 제시되었다. 따라서 중약진지역에 위치한 구조물의 내진설계에 대한 별도의 연구가 요구되고 있다. 이 연구에서는 중약진지역에 위치한 콘크리트 교량을 선정하여 비선형 동적거동을 반영하는 계수를 결정하고 응답스펙트럼 해석법을 적용하였다. 연구 결과 바탕으로 중약진지역의 교량에 대해 내진설계의 목적을 만족하는 개선된 내진설계 절차를 제시하였다.

• 한국생산제조학회지
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• 제24권1호
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• pp.87-93
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• 2015

The dynamic responses of a telescope loaded on an STSAT-3 satellite were analyzed, and environmental tests were conducted to verify the reliability of the design. The space use telescope COMIS (compact imaging spectrometer) is a major payload of the STSAT-3 launched on November 21, 2013. Vibration responses such as the acceleration, displacement, and velocity with respect to random vibration and shock impulse inputs were obtained based on theoretical fundamentals in conjunction with finite element analysis. The main focus of this study was on developing technology for accurate and/or favorable modeling and analysis of the structure and fitting the results to that of experiments. Cutting-edge technology for manipulating the vibrations of a space use telescope is suggested.

• Computers and Concrete
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• 제18권6호
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• pp.1195-1211
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• 2016

In this study, seismic behaviour of reinforced concrete buildings using the pushover and incremental dynamic analysis method was investigated. A numerical study was performed for a reinforced concrete frame building. Pushover analysis according to uniform and triangular load shapes and incremental dynamic analyses were performed for selected building. For the nonlinear analysis, three ground motion records were selected to ensure compatibility with the design spectrum defined in the Turkish Seismic Code. The maximum response, dynamic pushover curve, capacity curves, interstorey drifts and moment rotation curves for various element ends of the selected building were obtained. Results were compared each other and good correlation was obtained between the dynamic analyses envelope with static pushover curves for the building.

• Computers and Concrete
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• 제25권4호
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• pp.343-354
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• 2020

In this paper, vibration characteristics of chiral double-walled carbon nanotubes entrenched on Kelvin's model. The Eringen's nonlocal elastic equations are being combined with Kelvin's theory to observe small scale response. A nonlocal model has been formulated to explore the frequency spectrum of chiral double-walled CNTs along with diversity of indices and nonlocal parameter. Wave propagation is proposed technique to establish field equations of model subjected to four distinct end supports. The significance of scale effect in relevance of length-to-diameter and thickness- to- radius ratios are discussed and displayed in detail.

• Earthquakes and Structures
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• 제10권1호
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• pp.191-209
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• 2016

Seismic codes are the best available guidance on how structures should be designed and constructed to ensure adequate resistance to seismic forces during earthquakes. Seismic provisions of Indian standard code, International building code and European code are applied for buildings with ordinary moment resisting frames and reinforced shear walls at various locations considering the effect of site soil conditions. The study investigates the differences in spectral acceleration coefficient ($S_a/g$), base shear and storey shear obtained following the seismic provisions in different codes in the analysis of these buildings. Study shows that the provision of shear walls at core in low rise buildings and at all the four corners in high rise buildings gives the least value of base shear.

• 한국재료학회지
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• 제32권8호
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• pp.333-338
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• 2022

In this work, we developed silver nanowires and a silicon based Schottky junction and demonstrated ultrafast broadband photosensing behavior. The current device had a response speed that was ultrafast, with a rising time of 36 ㎲ and a falling time of 382 ㎲, and it had a high level of repeatability across a broad spectrum of wavelengths (λ = 365 to 940 nm). Furthermore, it exhibited excellent responsivity of 60 mA/W and a significant detectivity of 3.5 × 10¹² Jones at a λ = 940 nm with an intensity of 0.2 mW cm^-2 under zero bias operating voltage, which reflects a boost of 50 %, by using the AC PV effect. This excellent broadband performance was caused by the photon-induced alternative photocurrent effect, which changed the way the optoelectronics work. This innovative approach will open a second door to the potential design of a broadband ultrafast device for use in cutting-edge optoelectronics.

• Structural Engineering and Mechanics
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• 제51권3호
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• pp.487-502
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• 2014

In buildings structures, the flexural stiffness reduction of beams and columns due to concrete cracking plays an important role in the nonlinear load-deformation response of reinforced concrete structures under service loads. Most Seismic Design Codes do not precise effective stiffness to be used in seismic analysis for structures of reinforced concrete elements, therefore uncracked section properties are usually considered in computing structural stiffness. But, uncracked stiffness will never be fully recovered during or after seismic response. In the present study, the effect of concrete cracking on the lateral response of structure has been taken into account. Totally 120 cases of 3 Dimensional Dynamic Analysis which considers the real and accidental torsional effects are performed using ETABS to determine the effective structural system across the height, which ensures the performance and the economic dimensions that achieve the saving in concrete and steel amounts thus achieve lower cost. The result findings exhibits that the dual system was the most efficient lateral load resisting system based on deflection criterion, as they yielded the least values of lateral displacements and inter-storey drifts. The shear wall system was the most economical lateral load resisting compared to moment resisting frame and dual system but they yielded the large values of lateral displacements in top storeys. Wall systems executes tremendous stiffness at the lower levels of the building, while moment frames typically restrain considerable deformations and provide significant energy dissipation under inelastic deformations at the upper levels. Cracking found to be more impact over moment resisting frames compared to the Shear wall systems. The behavior of various lateral load resisting systems with respect to time period, mode shapes, storey drift etc. are discussed in detail.

• 융합정보논문지
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• 제12권3호
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• pp.151-157
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• 2022

차량의 진행을 근사화한 외부 가진력을 고려한 강제 진동에서의 주파수 특성을 알아보고자 하였고, 다양한 가진 진폭과 주파수를 갖는 외력이 작용하면서 차량이 둔턱을 넘어갈 때에 차량에서 일어나는 주파수 영역의 진동특성을 분석하였다. 응답은 수치해석을 통하여 변위, 속도 및 가속도 등의 응답을 구하였고 이들을 FFT 처리하여 각 시간 응답의 FRF(Frequency response function) 주파수 특성을 분석하였다. 특히, 차량 고유모드와 외부 가진 모드의 발생 위치를 확실하게 비교하여 밝혔고 외부 가진력에 의한 강제진동 모델에서 변위, 속도 및 가속도의 거동과 주파수 응답함수에서의 고유모드의 위치와 주변의 가진 모드 분포 및 파워 스펙트럼, 실수부와 허수부의 FRF도 나타났으며 각 FRF에서 근접 모드 특성도 분석하였다. 외부 가진력으로 정현파의 가진력과 임펄스 가진력에 의한 둔턱 주파수를 고려하여 가정한 근사 모델에서 발생 모드를 구별할 수 있었다. 상당하는 질량, 감쇠 및 강성을 변화하는 여러 시스템에서 강제진동의 응답특성을 체계적으로 다루었다.

• 토지주택연구
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• 제5권2호
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• pp.115-120
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• 2014

현재 국내 내진설계기준에서 제시하고 있는 지반분류 방법 및 지반 증폭계수는 기반암이 주로 30m 이내에 위치하는 일반적인 국내 지반특성을 제대로 반영하지 못하고 있다. 따라서, 본 연구에서는 점성토 지반에 근입된 비정형 말뚝기초(PHC 500, 중심 간격 3D)에 대한 동적 원심모형 실험을 실시하여 자유장과 기초판의 응답 스펙트럼 결과를 비교하였다. 장주기 영역에서는 SE 지반의 설계 스펙트럼 가속도보다 기초와 자유장에서 계측된 실제 스펙트럼 가속도가 작게 나타났고, 기초에서 발생한 스펙트럼 가속도는 지진 하중이 커지면 SD 지반의 설계 스펙트럼 가속도와 유사해지는 것을 확인할 수 있었다. 이것은 연약한 지반(SE 지반)에 대한 현행 설계기준이 지진 하중을 과대평가하고 있으며 비경제적 설계를 할 수 있음을 의미한다. 1.5초 이상의 장주기 영역에서는 실험에서 측정된 스펙트럼 가속도가 SC 지반의 표준설계응답스펙트럼 가속도보다 작게 나타났고 기초 및 자유장 조건에 의한 스펙트럼 가속도 차이가 거의 발생하지 않았다. 따라서, 실제 아파트에 해당하는 1.5초 이상의 장주기에서는 국내 지반조건을 고려하여 실험에서 측정된 스펙트럼 가속도를 설계에 적용하면 표준설계스펙트럼을 적용할 때 보다 경제적인 설계가 가능한 것으로 나타났다.