• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.732-737
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• 2005

This paper performed pseudo static analysis and dynamic analysis for CFRD and evaluated reliability with the results of Shaking Table Test. The Seismic coefficient method, modified seismic coefficient method, Newmark method of Pseudo static analysis and frequency domain response analysis, time domain history analysis of dynamic analysis were used. The analysis results were differ between analysis method, but the trends of acceleration and displacement were good agreement with the results of shaking table test.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.1159-1164
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• 2005

Seismic analysis methods in use on ground structure are equivalentstatic analysis, response-displacement method and dynamic analysis etc. Equivalentstatic analysis does not considerdynamic effect, and dynamic analysis process is very complex. then 'Urbanrail transit earthquake-resistance design standard (2005.06)' is persuading that analyze by response displacement method that consider enough dynamic effect of ground structure statically. But, It is very complex and difficult to apply response-displacement method in the field. So, modified equivalentstatic analysis or pseudo static analysis that is easy to apply in the field and have rationality of design is practically used. In this study, I try to prescribe the applicable scale of structure and static analysis that have calculative effectiveness about response-displacement method by comparing and analyzing the result of each analysis method according to the scale of urban rail transit' box type concrete structure and by performing seismic analysis that apply modified equivalentstatic analysis, pseudo static analysis and response-displacement method changing the kind of ground, depth of bedrock, size of structure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.421-424
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• 2004

Model updating is a very active research field, in which significant efforts has been invested in recent years. Model updating methodologies are invariably successful when used on noise-free simulated data, but tend to be unpredictable when presented with real experimental data that are-unavoidably-corrupted with uncorrelated noise content. In this paper, Reanalysis using frequency response functions for correlating and updating dynamic systems is presented. A transformation matrix is obtained from the relationship between the complex and the normal frequency response functions of a structure. The transformation matrix is employed to calculate the modified damping matrix of the system. The modified mass and stiffness matrices are identified from the normal frequency response functions by using the least squares method. Full scale pseudo dynamic pier test is employed to illustrate the applicability of the proposed method. The result indicate that the damping matrix of correlated finite element model can be identified accurately by the proposed method. In addition, the robustness of the new approach uniformly distributed measurement noise is also addressed.

• Journal of Astronomy and Space Sciences
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• 제26권1호
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• pp.59-74
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• 2009

Relative navigation system is presented using GPS measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide the real-time inter-satellite relative positions as well as absolute positions for two formation flying satellites in low earth orbit. To improve the navigation performance, the absolute states are estimated using ion-free GRAPHIC (group and phase ionospheric correction) pseudo-ranges and the relative states are determined using double differential carrier-phase data and singled-differential C/A code data based on the extended Kalman filter and the unscented Kalman filter. Furthermore, pseudo-relative dynamic model and modified relative measurement model are developed. This modified EKF method prevents non-linearity of the measurement model from degrading precision by applying linearization about absolute navigation solutions not about the priori estimates. The LAMBDA method also has been used to improve the relative navigation performance by fixing ambiguities to integers for precise relative navigation. The software-based simulation has been performed and the steady state accuracies of 1 m and 6 mm ($1{\sigma}$ of 3-dimensional difference errors) are achieved for the absolute and relative navigation using EKF for a short baseline leader/follower formation. In addition, the navigation performances are compared for the EKF and the UKF for 10 hours simulation, and relative position errors are mm-level for the two filters showing the similar trends.

• 한국산학기술학회논문지
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• 제12권9호
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• pp.4239-4249
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• 2011

일본과 같은 지진 빈발국은 CFRD의 경우 지진시 댐제체 상류부의 Face Slab에 응력이 집중하여 파괴되는 경우를 대부분 상정하여 내진안정성을 평가한다. 그러나 우리나라에서는 현재까지 이에 대한 명확한 해석방법이 확립되어 있지 않다. 본 논문은 CFRD에 대하여 등가정적해석 및 동적해석 수행 후 진동대시험과 비교하여 그 신뢰성을 평가하였다. 등가정적해석은 진도법, 수정진도법, Newmark법을 적용하였고 동적해석은 주파수응답해석, 시간이력 해석법을 적용하였다. 해석결과 해석 방법별 편차는 발생하나 가속도 및 변위의 발생경향은 진동대시험 결과와 잘 일치하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.620-625
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• 2009

The seismic slope stability is most often evaluated by the pseudo-static limit analysis, in which the earthquake loading is simplified as static inertial loads acting in horizontal and/or vertical directions. The transient loading is represented by constant acceleration via the pseudostatic coefficients. The result of a pseudostatic analysis is governed by the selection of the value of the pseudostatic coefficient. However, selection of the value is very difficult and often done in an ad hoc manner without a sound physical reasoning. In addition, the maximum acceleration is commonly estimated from the design guideline, which cannot accurately estimate the dynamic response of a slope. There is a need to perform a 2D dynamic analysis to properly define the dynamic response characteristics. This paper develops the modified one-dimensional seismic site response analysis. The modified site response analysis adjusts the density of the layers to simulate the change in mass and weight of the layers of the slope with depth. Multiple analyses are performed at various locations within the slope to estimate the change in seismic response of the slope. The calculated peak acceleration profiles with depth from the developed procedure are compared to those by the two-dimensional analyses. Comparisons show that the two methods result in remarkable match.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2011년도 정기 학술대회
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• pp.324-327
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• 2011

The design requirement for ground mounted sign structures are fairly well defined in the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals and consists of applying an equivalent pseudo-dynamic loading to account for the dynamic effects of wind loads and ignores the dynamic effect due to moving vehicle loads. This design approach, however, should not be applied to the design of bridge mounted sign structures because ignoring the dynamic effects of the moving vehicle loads may produce non-conservative results, since the stiffness of the bridge structure can greatly influence the behavior. Not enough information is available in the literatures which provide guide lines to include the influence of moving vehicles in the design of the bridge mounted sign structures. This paper describes a theoretical methodology, Bridge-Vehicle Interaction Element, which can be utilized to account for the dynamic effect of moving vehicles. A case study is also included where this methodology was successfully applied. It was concluded that the bridge-vehicle interaction finite element developed can provide a more accurate representation of the behavior of bridge mounted sign structures. The result of these analysis enabled development of simple and effective retrofitting scheme for the existing support system of bridge-mounted-structure.

• 한국항공우주학회지
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• 제32권10호
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• pp.67-76
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• 2004

본 논문에서는 기존의 Fly-the-wire에 기초한 정지위성 자동위치유지 시스템을 보완하고 시뮬레이션을 통하여 그 성능을 분석하였다. 사용된 탑재용 자동위치유지 알고리즘은 지상의 두 지점에 위치한 장비로부터 Pseudo-Range 선호를 수신하여 실시간 궤도결정을 수행 한 다음, 이를 기준궤도를 추종하도록 궤도제어 명령을 생성한다. 본 논문에서는 기존의 Fly-the-wire 방식이 가지는 연료 사용의 비효율성을 해결하기 위하여 Modified fly-the-wire 방식을 제안하였는데 본 기법은 기준궤도로부터 벗어난 오차성분을 하모닉 성분과 선형증가 성분으로 분리한 다음, 하모닉 성분은 피드백제어기를 이용하여 제어하고 선형증가 성분은 기준기동을 수정하여 보정하는 방식을 취하였다. 마지막으로 시뮬레이션을 통하여 제안된 시스템의 추종성능 및 연료사용량을 분석하였다.

• 폴리머
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• 제24권3호
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• pp.366-373
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• 2000

본 연구에서는 poly(phenylene sulfide)(PPS)와 ABS의 물성을 상호보완하기 위하여 블렌드를 제조하였다. 각 성분간의 상용성을 증진시키기 위하여 소량의 무수말레인산을 ABS에 반응시켜 MABS (ABS-g-MAH)를 제조하였으며, PPS/ABS 및 PPS/MABS 블렌드는 이축 혼련 압출기를 이용하여 용융 흔합하였다. 블렌드에서 ABS의 화학적 개질이 블렌드의 모폴로지와 열적 성질에 미치는 영향을 관찰하였다. PPS/MABS 블렌드의 경우, 각 성분간에 강한 인력이 형성되는 것을 광학현미경과 SEM을 이용하여 확인하였으며, DMA 분석에서는 단일 유리전이 온도를 확인하였다. 또한 화학적으로 개질된 MABS를 사용한 PPS/MABS의 블렌드는 PPS/ABS보다 향상된 열적 성질을 나타내었다.

• Earthquakes and Structures
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• 제8권5호
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• pp.1241-1254
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• 2015

Spatially variable ground motions can be significant on the seismic response of a structure due to the incoherency of the incident wave. Incoherence of the incident wave is resulted from wave passage and wave scattering. In this study, wave passage effect on the response spectrum of a building structure built on a soft soil layer was investigated utilizing a finite element program of P3DASS (Pseudo 3-dimensional Dynamic Analysis of a Structure-soil System). P3DASS was developed for the axisymmetric problem in the cylindrical coordinate, but it is modified to apply anti-symmetric input earthquake motions. Study results were compared with the experimental results to verify the reliability of P3DASS program for the shear wave velocity of 250 m/s and the apparent shear wave velocities of 2000-3500 m/s. Studied transfer functions of input motions between surface mat foundation and free ground surface were well-agreed to the experimental ones with a small difference in all frequency ranges, showing some reductions of the transfer function in the high frequency range. Also wave passage effect on the elastic response spectrum reduced the elastic seismic response of a SDOF system somewhat in the short period range.