• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.110-113
• /
• 2006

This paper describes the development process of body and full vehicle for reduced idle vibration through the data level of frequency and sensitivity. The vibration mode map is used to separate body structure modes from resonance of engine idle nm and steering system. This paper describes the analysis approach process to reduce the variation of uncertainties for idle vibration performance at initial design stage. The robust design method is performed to increase the stabilization performance under vehicle vibration. It is used to predict the effects of the stiffness deviation according to the spot welding condition of the body structure. The tolerance associated with hood over slam bumper is analyzed for the quality deviation of the moving system in full vehicle. And the glass sealant stiffness and weight difference is considered for the deviation characteristic. The design guideline is suggested considering sensitivity about body and full vehicle by using mother car at initial design stage. It makes possible to design the good NVH performance and save vehicles to be used in tests. These improvements can lead to shortening the time needed to develop better vehicles.

• Geomechanics and Engineering
• /
• 제24권3호
• /
• pp.295-305
• /
• 2021

In this study, design charts for estimating consolidation settlement are proposed according to finite strain consolidation theory using a nonlinear constitutive relationship equation. Results of parametric sensitivity analysis shows that the final settlement, initial height, and initial void ratio exerted the greatest effect, and the coefficients of the void ratio-effective-stress. Proposed design charts were analyzed for three regions using a representative constitutive relationship equation that enables major dredged-reclaimed construction sites in Korea. The regional design charts can be calculated accurately for the final settlement because it is applied directly to the numerical analysis results, except for reading errors. A general design chart applicable to all marine clays is proposed through correlation analysis of the main parameters. A final self-weight consolidation settlement with various initial void ratios and initial height conditions should be estimated easily using the general design chart and constitutive relationship. The estimated final settlement using the general design chart is similar to the results of numerical analysis obtained using finite strain consolidation theory. Under an overburden pressure condition, design charts for estimating consolidation settlement are proposed for three regions in Korea.

• 한국수소및신에너지학회논문집
• /
• 제8권4호
• /
• pp.145-154
• /
• 1997

Pd, Pd-Rh 게이트 MOS센서의 $H_2$, $H_2S$ 검지특성과 Pd박막의 중착조건이 감지특성에 미치는 영향에 대해서 조사하였다. rf power의 증가와 증착온도의 증가는 모두 센서의 감도와 초기반응속도를 감소시켰으며 rf power의 변화보다는 증착온도의 변화에 의한 효과가 현저하였다. Pd-Rh 센서의 경우 순수한 Pd 센서에 비해 감도가 낮았으며 Rh의 양이 증가할수록 감도는 감소하였다. Pd-Rh 센서에서 $H_2$가 $H_2S$보다 더 뛰어난 감도를 보여주었다. rf power, 증착온도, 기판의 변화가 MOS센서의 감도나 초기반응속도 등의 센서특성에 영향을 미친다는 사실을 확인할 수 있었다.

• 소성∙가공
• /
• 제19권8호
• /
• pp.494-501
• /
• 2010

The main objective of this study is to examine the sensitivity of calibration curves of FEA of ring compression test to frictional shear factor. Ring compression test has been investigated by measuring dimensional changes at different positions of ring specimen and they include the changes in internal diameter at the middle and top section of the specimen, outer diameter at the middle and top section, surface expansion at the top surface, respectively. Initial ring geometries employed in analysis maintain a fixed ratio of 6 : 3 : 2, i.e. outer diameter : inner diameter : thickness of the ring specimen, which is generally known as 'standard' specimen. A rigid plastic material for different work-hardening characteristics has been modeled for simulations using rigid-plastic finite element code. Analyses have been performed within a definite range of friction as well as over whole range of friction to show different sensitivities to the interfacial friction for different ranges of friction. The results of investigation in this study have been summarized in terms of a dimensionless gradient. It has been known from the results that the dimensional changes at different positions of ring specimen show different linearity and sensitivity to the frictional condition on the contact surface.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
• /
• pp.508-513
• /
• 1997

One of the moot important constants to be Installed In COLSS, a monitoring system in CE typed reactors, is ROPM which would limit the operating space. This static ROPM was calculated from digital transient analysis assuming that every design basis transient was initiated from the most severe initial condition combination (LCO). Once It could be assured that core condition would not be located at none other than LCO, this static ROPM could be replaced with dynamic ROPM calculated at that condition and the dynamic ROPM would be definitely less than the static ROPM. In order to do, It must be required to calculate the transient discrete sensitivity parameters and parameters change distribution. The purpose of this report is just to propose the enlargement method for thermal margin.

• 한국습지학회지
• /
• 제23권4호
• /
• pp.342-351
• /
• 2021

이 연구의 목적은 MODFLOW를 이용하여 신규 지하수 관정 추가로 인한 영향을 예측하기 위해 지하수의 변화와 지하수두 또는 매개변수 민감도에 미치는 영향을 평가하는 것이다. 이 연구에서는 동해시의 전천유역 하류지역을 대상으로 두 가지 조건을 모의하였다. 첫 관측된 지하수위값을 이용하여 자연상태 정류 흐름을 모의 할 수 있는 매개변수를 결정한 후, 이미 설치되어 있는 관정까지 포함하여 모형을 구축하였다. 구축된 모형을 이용하여 지하수 관정의 추가 설치에 따른 영향을 모의하였다. 두 번째는 동해시의 물 부족 문제를 해결하기 위한 방법으로 관정을 계획하고 모의하였다. 모의 결과, 최대 지하수위 저하는 첫 번째 대수층에서 약 0.35m로 나타났으며, 이는 해수의 침입은 발생하지 않는다는 것과 관정의 계획이 물 부족의 해결책으로 무리가 없다는 것을 나타낸 것이다. 마지막으로 MODFLOW에서 사용되는 매개변수의 민감도 분석을 실시하였다. 민감도 분석 결과에서 초기 수두, 비등방성 계수, 수리전도도 및 일반수두경계가 민감한 매개변수로 판명되었다.

• 대한전자공학회논문지SP
• /
• 제39권4호
• /
• pp.361-369
• /
• 2002

제한된 구역내의 고정(static)된 감시 카메라를 통해 입력된 영상 데이터에 대해 움직임이 있는 물체를 검출하기 위해서는 주위 잡음(noise)에 대한 민감성(sensitivity)과 상황변화에 대해 대처할 수 있는 강인한 알고리즘이 요구된다. 본 논문에서는 이러한 잡음이나 갑작스런 상황의 변화에 적절히 대응하여 움직임 물체를 추출하고 추적하는 효율적인 알고리즘을 제안한다. 초기 배경 모델(background model) 영상에 의해서 입력되는 영상 내에 이동 물체가 존재할 경우 각 화소의 주변의 변화를 고려하여 움직임 영역을 검출하였다. 움직임 영역의 화소들의 잡음 제거를 위해 형태학적 필터(morphological filter)를 사용하였고, 8-연결 성분 표시(connected component labeling)에 의해 개별적인 물체의 움직임을 검출하였다. 마지막으로 다양한 환경과 모델에 따른 실험결과와 통계적인 분석을 제시하였다.

• Coupled systems mechanics
• /
• 제12권4호
• /
• pp.365-389
• /
• 2023

Dynamic analysis of a typical concrete gravity dam-reservoir system is formulated by FE-(FE-TE) approach (i.e., Finite Element-(Finite Element-Truncation Element)). In this technique, dam and reservoir are discretized by plane solid and fluid finite elements. Moreover, the H-W (i.e., Hagstrom-Warburton) high-order condition imposed at the reservoir truncation boundary. This task is formulated by employing a truncation element at that boundary. It is emphasized that reservoir far-field is excluded from the discretized model. The formulation is initially reviewed which was originally proposed in a previous study. Thereafter, the response of Pine Flat dam-reservoir system is studied due to horizontal and vertical ground motions for two types of reservoir bottom conditions of full reflective and absorptive. It should be emphasized that study is carried out under high order of H-W condition applied on the truncation boundary. The initial part of study is focused on the time harmonic analysis. In this part, it is possible to compare the transfer functions against corresponding responses obtained by FE-(FE-HE) approach (referred to as exact method). Subsequently, the transient analysis is carried out. In that part, it is only possible to compare the results for low and high normalized reservoir length cases. Therefore, the sensitivity of results is controlled due to normalized reservoir length values.

• 전산구조공학
• /
• 제10권3호
• /
• pp.167-174
• /
• 1997

계가 혼돈거동을 나타낼 경우에는 변수들의 미소변화에 의해서도 계가 전혀 다른 거동을 나타낼 수 있기 때문에 비선형계의 설계 및 해석시에는 이를 고려해야 한다. 따라서 본 연구에서는 구형 쉘의 중앙에 충격하중이 수직방향으로 작용하는 경우, 쉘의 기하학적 비선형성과 재료적 비선형성으로부터 기인되는 혼돈거동을 해석하였다. 쉘의 탄소성거동을 유한요소법을 이용하여 구한 후 계의 거동을 변위-시간이력, 프앙카레 맵, phase diagram등의 표준적인 방법들을 이용하여 쉘의 혼돈거동을 규명하였다. 해석결과, 계는 혼돈거동을 나타내었으나 탄소성보의 경우와는 달리 초기조건의 미소변화에 대한 극도의 민감도는 나타나지 않았으며 시간에 대한 쉘의 거동특성도 크게 변하지 않았다. 프앙카레 맵은 한정된 영역에 결쳐서 점들이 분포되었기 때문에 계의 거동이 혼돈거동임을 보여 주고 있지만 혼돈계의 프앙카레 맵에서 나타나는 기하학적 구조는 나타나지 않았다. 에너지선도를 이용하여 쉘이 하중의 작용방향 또는 반대방향으로 불규칙적으로 snap-through되는 원인을 규명하였다.

• 한국도로학회논문집
• /
• 제19권4호
• /
• pp.19-25
• /
• 2017

PURPOSES : In this paper, the flow of construction material was simulated using computational fluid dynamics in a 2D axisymmetric condition to evaluate the effect of initial or varying material properties on the final shape of a specimen. METHODS : The CFD model was verified by using a well-known analytical solution for a given test condition followed by performing a sensitivity analysis to evaluate the effect of material properties on the final shape of material. Varying dynamic viscosity and yield stress were also considered. RESULTS : The CFD model in a 2D axisymmetric condition agreed with the analytical solution for most yield stress conditions. Minor disagreements observed at high yield stress conditions indicate improper application of the pure shear assumption for the given material behavior. It was also observed that the variation of yield stress and dynamic viscosity during curing had a meaningful effect on the final shape of the specimen. CONCLUSIONS : It is concluded that CFD modeling in a 2D axisymmetric condition is good enough to evaluate fluidal characteristics of material. The model is able to consider varying yield stress and viscosity during curing. The 3D CFD-DEM coupled model may be required to consider the interaction of aggregates in fluid.