• Structural Engineering and Mechanics
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• 제44권5호
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• pp.681-704
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• 2012

The dynamic response of Euler-Bernoulli beams to resonant harmonic moving loads is analysed. The non-dimensional form of the motion equation of a beam crossed by a moving harmonic load is solved through a perturbation technique based on a two-scale temporal expansion, which permits a straightforward interpretation of the analytical solution. The dynamic response is expressed through a harmonic function slowly modulated in time, and the maximum dynamic response is identified with the maximum of the slow-varying amplitude. In case of ideal Euler-Bernoulli beams with elastic rotational springs at the support points, starting from analytical expressions for eigenfunctions, closed form solutions for the time-history of the dynamic response and for its maximum value are provided. Two dynamic factors are discussed: the Dynamic Amplification Factor, function of the non-dimensional speed parameter and of the structural damping ratio, and the Transition Deamplification Factor, function of the sole ratio between the two non-dimensional parameters. The influence of the involved parameters on the dynamic amplification is discussed within a general framework. The proposed procedure appears effective also in assessing the maximum response of real bridges characterized by numerically-estimated mode shapes, without requiring burdensome step-by-step dynamic analyses.

• 한국지진공학회논문집
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• 제27권1호
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• pp.1-12
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• 2023

Structures of high-rise buildings are less prone to earthquake damage. This is because the response acceleration of high-rise buildings appears to be small by generally occurring short-period ground motions. However, due to the increased construction volume of high-rise buildings and concerns about large earthquakes, long-period ground motions have begun to be recognized as a risk factor for high-rise buildings. Ground motion observed on each floor of the building is affected by the eigenmode of the building because the ground motion input to the building is amplified in the frequency range corresponding to the building's natural frequency. In addition, long-period components of ground motion are more easily transmitted to the floor or attached components of the building than short-period components. As such, high-rise buildings and non-structural components pose concerns about long-period ground motion. However, the criteria (ASCE 7-22) underestimate the acceleration response of buildings and non-structural components caused by long-period ground motion. Therefore, the characteristics of buildings' acceleration response amplification ratio and non-structural components were reviewed in this study through shake table tests considering long-period ground motions.

• 한국농공학회논문집
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• 제60권2호
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• pp.95-101
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• 2018

The objective of this study is to evaluate the liquefaction cyclic shear stress ratio considering the soil uncertainty. In this study, the probabilistic ground response analysis and the cyclic shear stress ratio analysis for the liquefaction potential evaluation are performed considering the soil variability. The statistical properties of input ground parameters were analyzed to investigate the parameters affecting the seismic response analysis. The Probabilistic analysis was carried out by Monte Carlo Simulation method. The ground response analysis was performed considering the soil variability and the probability distribution characteristics of the ground acceleration. The probability distribution of the peak ground acceleration by seismic characteristics was presented. The differences of liquefaction shear stress ratio results according to soil variability were compared and analyzed. The maximum acceleration of the ground by the deterministic method was analyzed to be overestimation of the ground amplification phenomenon. Also, the shear stress ratio was overestimated.

• Asian Pacific Journal of Cancer Prevention
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• 제13권1호
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• pp.329-337
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• 2012

Considerable attention has been given to the accuracy of HER-2 testing and the correlation between the results of different testing methods. This interest reflects the growing importance of HER-2 status in the management of patients with breast cancer. In this study the detection of HER-2 gene and centromere 17 status was evaluated using dual-colour primed in situ labelling (PRINS) in comparison with fluorescence in situ hybridization (FISH). These two methods were evaluated on a series of 27 formalin fixed paraffin embedded breast carcinoma tumours, previously tested for protein overexpression by HercepTest (grouped into Hercep 1+/0, 2+ and 3+). HER-2 gene amplification (ratio${\geq}2.2$) by PRINS was found in 3:3, 6:21 and 0:3 in IHC 3+, 2+ and 1+/0 cases, respectively. Comparing FISH and IHC (immunohistochemistry), showed the same results as for PRINS and IHC. Chromosome 17 aneusomy was found in 10 of 21 IHC 2+ cases (47.6%), of which 1 (10%) showed hypodisomy (chromosome 17 copy number per cell${\leq}1.75$), 7 (70%) showed low polysomy (chromosome 17 copy number per cell=2.26 - 3.75) and 2 (20%) showed high polysomy (chromosome 17 copy number per cell ${\geq}3.76$). The overall concordance of detection of HER-2 gene amplification by FISH and PRINS was 100% (27:27). Furthermore, both the level of HER-2 amplification and copy number of CEN17 analysis results correlated well between the two methods. In conclusion, PRINS is a reliable, reproducible technique and in our opinion can be used as an additional test to determine HER-2 status in breast tumours.

• 한국강구조학회 논문집
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• 제22권1호
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• pp.87-97
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• 2010

본 연구는 비대칭 비가새 골조를 대상으로 강구조 설계기준에서 제시하고 있는 하중증폭계수를 적용한 2차 해석법의 타당성을 해석적 방법을 통해 평가하는데 그 목적이 있다. 이를 위해 KBC 2005에서 제안하고 있는 B1 및 B2 계수를 적용한 2차 해석과 KBC 2009에서 제안하고 있는 하중증폭계수를 적용한 직접해석을 5층 2스팬 및 5층 4스팬 비대칭 비가새 강구조 골조에 대해 실시하고, 그 해석 결과를 2차 비탄성 해석 결과와 비교하여 기준에서 제안된 2차 해석법들을 평가하였다. 해석의 주요 변수로는 골조 형상, 기둥 축력비, 해석방법, 기둥수평위치 등이 적용되었다. 연구 결과 구조물의 비대칭성은 B2 계수 및 제안된 해석법의 유효성에 영향을 미치는 것으로 나타났으며, 특히 기둥삭제 및 경사 기둥의 경우 오차의 범위가 증가하는 것으로 나타났다.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.3074-3080
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• 2013

평면 수리실험을 통해 경사식구조물의 오목부 구간에 대한 파고 증폭을 검토하였다. 실험에 적용된 경사식 구조물 단면은 1:1.5의 경사면에 테트라포드가 2층 피복되어 있는 형상이다. 실험파는 Bretschneider-Mitsuyasu 스펙트럼을 적용한 불규칙파를 적용하였으며, 오목부의 중심각도는 $120^{\circ}$, $140^{\circ}$와$160^{\circ}$를 적용하였다. 실험결과에 따르면 오목부 구간에서의 입사파고에 대한 파고증폭비는 본 실험에서 적용한 실험조건 내에서 최대 1.5배로 계측되었으며, 상대파고비의 분포형태는 오목부의 중심에서 최대가 되고, 오목부를 중심으로 거리가 멀어질수록 감소했다 다시 증가하는 형태인 W자 형태를 나타내었다.

• 한국지반신소재학회논문집
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• 제19권4호
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• pp.51-63
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• 2020

본 연구에서는 지진가속도 계측기의 계측 데이터를 사용하여 저수지의 동적해석방법에 대한 모형 검정 및 저수지 높이에 따른 지진가속도 증폭 특성을 분석하였다. 모형을 검정하기 위해 댐 기초의 계측 데이터를 입력 데이터로 사용하였고 해석 결과를 댐 상부의 계측 데이터와 비교한 결과 수치해석을 이용해 출력된 지진파와 계측 지진파의 최댓값과 그 파형이 비슷하게 나타났고 지진가속도 증폭 특성의 경우 지진가속도 증폭비는 저수지의 높이와 지진의 크기에 비례하는 것으로 나타났다. 본 연구를 통해 저수지에 설치된 가속도계에서 얻은 계측 데이터를 활용하여 반복 탄소성 구성식을 이용한 동적해석방법은 지진파 특성 분석이 적절하게 수행될 수 있는 기법임을 확인하였고 향후 이러한 기법을 적용해 저수지의 지진가속도 계측기의 활용도를 제고할 수 있을 것으로 판단된다.

• 한국광학회지
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• 제12권6호
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• pp.507-510
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• 2001

간단한 비선형 증폭 루프에서의 평균 솔리톤 전송의 안정성을 비선형 Schroedinger방정식에 기초한 수치해석법을 이용하여 솔리톤 주기에 대한 증폭 주기의 비율과 루프에서의 erbium doped광섬유의 길이 비율을 변화시켜가며 계산하고 그 결과를 분석하였다. 계산 결과 루프에서의 erbium doped광섬유의 길이 비율이 작을 경우 증폭 주기가 솔리톤 주기에 비해 많이 작아야 한다는 기존의 평균 솔리톤 형성 조건이 완화됨을 알 수 있었다.

• 대한임베디드공학회논문지
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• 제14권2호
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• pp.71-78
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• 2019

As the capacity of SSDs rapidly increases, the amount of DRAM to keep a mapping table size in SSDs becomes very huge. To address a Demand-based FTL (DFTL) scheme that caches part of mapping entries in DRAM is considered to be a feasible alternative. However, owing to its unpredictable behaviors, DFTL fails to provide consistent I/O response times. In this paper, we a) analyze a root cause that results in fluctuation on read latency and b) propose a new demand-based FTL scheme that ensures guaranteed read response time with low write amplification. By preventing mapping evictions while serving reads, the proposed technique guarantees every host read requests to be done in 2 NAND read operations. Moreover, only with 25% of a cache ratio, the proposed scheme improves random write performance and random mixed performance by 1.65x and 1.15x, respectively, over the traditional DFTL.

• Structural Engineering and Mechanics
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• 제82권4호
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• pp.503-515
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• 2022

The multi-rigid-body matrix method (MRBMM) is a generalized modeling method for obtaining the displacements, forces, and dynamic characteristics of a compliant mechanism without performing inner-force analysis. The method discretizes a compliant mechanism of any type into flexure hinges and rigid bodies by implementing a multi-body mass-spring model using coordinate transformations in a matrix form. However, in this method, the deformations of bodies that are assumed to be rigid are inherently omitted. Consequently, it may yield erroneous results in certain mechanisms. In this paper, we present a multi-compliant-body matrix-method (MCBMM) that considers a rigid body as a compliant element, while retaining the generalized framework of the MRBMM. In the MCBMM, a rigid body in the MRBMM is segmented into a certain number of body nodes and flexure hinges. The proposed method was verified using two examples: the first (an XY positioning stage) demonstrated that the MCBMM outperforms the MRBMM in estimating the static deformation and dynamic mode. In the second example (a bridge-type displacement amplification mechanism), the MCBMM estimated the displacement amplification ratio more accurately than several previously proposed modeling methods.