• 생물환경조절학회지
• /
• 제1권1호
• /
• pp.28-36
• /
• 1992

The wind pressure distributions were analyzed to provide fundamental criteria for the structural design on e single-span arched house according to the wind directions through the wind tunnel experiment. In order to investigate the wind force distributions, the variation of the wind force coefficients, the mean wind force coefficients, the drag force coefficients and the lift force coefficients were estimated by using the experimental data. The results obtained are as follows: 1. When the wind direction was normal to the wall, the maximum positive wind pressure along the height of the wall occurred approximately at two-thirds of the wall height because of the effects of boundary layer flow. 2. When the wind direction was 30$^{\circ}$ to the wall, the maximum positive wind force occurred at the windward edge of the wall. When the wind direction was parallel to the wall, the maximum negative wind force occurred at the windward edge of the wall. 3. The maximum negative wind force along the width of the roof appeared around the width ratio, 0.4, and that along the length of the roof appeared around the length ratio, 0.5. 4. According to the results of the mean wind force coefficients analysis, the maximum negative wind force occurred on the roof at the wind direction of 30$^{\circ}$. 5. The wind forces at the wind direction of 30$^{\circ}$ instead of 0$^{\circ}$ are recommended in the structural design of supports for a house. 6. To prevent partial damage of a house structure by wind forces, the local wind forces should be considered to the structural design of a house.

• 한국강구조학회 논문집
• /
• 제18권6호
• /
• pp.697-706
• /
• 2006

타워크레인의 횡방향 지지와 마스트의 횡강성 및 강도를 확보하기 위하여 횡하중 저항요소로서 사용되는 것이 월타이(wall tie)이다. 본 연구에서는 국내에서 가장 많이 사용되고 있는 독일 립헬사의 T형 타워크레인(기종 290HC, 작업반경: 70m, 인양하중: 12tf)을 대상으로 하고 마스트 및 월타이의 사용부재는 H형강보 구조의 구조물을 모델로 선정하여 월타이의 부재력, 월타이의 각도변화 및 각도범위에 따른 부재력의 변화를 분석하여, 실용적이고 안전한 월타이의 각도범위를 제안하여 현장기술자가 최적의 월타이를 배치할 수 있도록 하였다. 본 연구를 통하여 건축용 타워크레인의 훅크양정을 증대시키기 위하여 설치되는 횡방향지지요소인 월타이의 부재력 계산식을 구하고, 이를 프로그래밍하여 마스트 중심과 월타이 브라켓 간 거리를 변화시키면서, 월타이 각도별 월타이 부재력을 반복계산하여 월타이 부재력 특성곡선을 그리고 이를 분석하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 추계학술대회논문집
• /
• pp.246-251
• /
• 2003

This paper presents an experimental study on the energy dissipation characteristics of viscous damping wall (VDW). VDW is consisted of a plate floating in a thin case made of steel plated filled with highly viscous silicone oil. Because VDW demonstrates both viscous damping and stiffness characteristics, the viscous resisting force can be expressed as the sum of velocity dependant viscous damping force and displacement dependant restoring force. The viscous resisting force and energy absorbing capacity can be easily adjusted by changing three factors, i.e. viscosity of the fluid, gap distance and area of the wall plates. VDW was tested using a series of harmonic (sinusoidal) displacement history having different frequency and amplitude and the force-displacement relationship was recorded. The relationship between dissipated energy with three factors and the influence of exciting frequency on resisting force were Investigated

• 대한기계학회논문집B
• /
• 제30권8호
• /
• pp.806-817
• /
• 2006

The motion of a small rigid particle in the shear flow near a stationary flat wall is investigated in the context of Stokes flow. The lift force proposed by Saffman and later modified by Mclaughlin and Mei is considered in the prediction of the particle motion far away from the wall. Later, the expression of the lift force is modified to take into account the effect of wall. In the analysis, gravity, lift and drag acting on a small rigid particle near the wall are taken into account. Both analytical and numerical results for the terminal velocities, distances from the wall and trajectories of the particle are presented. In addition, we extended the present analysis to turbulent near-wall flow in the vicinity of the wall.

• 한국지반공학회논문집
• /
• 제19권2호
• /
• pp.107-121
• /
• 2003

중력식 안벽의 내진 안정성을 분석할 때, 중력식 안벽에 발생하는 하중성분의 크기와 위상관계를 명확히 결정하는 것이 중요하다. 일반적으로 안벽에 발생하는 하중성분은 안벽 관성력, 토압 그리고 수압으로 구성되어 있으며, 각 하중성분들의 크기와 위상관계는 배면지반에 발생하는 과잉간극수압의 크기에 따라 변한다. 벽체배면과 뒤채움 토체 사이의 접촉면에서 발생하는 동적작용력은 이러한 힘들의 상호작용에 의하여 발생한다 본 연구에서는 벽체 작용하중 산정식들로부터 구한 각 하중성분들의 크기를 조합하여 배면 동적작용력의 크기와 위상변화를 배면 과잉간극수압의 함수로써 산정하는 간단한 하중산정 모델을 제안하였으며, 진동대 실험결과와 이 모델의 예측결과를 비교하여 모델의 적용성을 검증하였다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1998년도 춘계학술대회논문집
• /
• pp.53-57
• /
• 1998

In order to investigate the effects of the variables during the stamping process upon the side wall curl behavior, experiments and finite element analyses were done using a 90 degree draw-bending test. The variables considered were the die radius, the forming speed, the restraint force, the lubrication and the sheet grade. The experiments and simulation conditions were selected according to the design of experiment (DOE) approach. The effects of the restraint force, the lubrication and the forming speed were the same for both high strength and mild steels, but the effects of the die radius on the side wall curl were dependent on the magnitude of the die radius and the sheet grade. A straight side wall was observed for both high strength and mild steels when the die radius was about 2∼3 times of the sheet thickness. It was recommended that the restraint force, the forming speed and the friction be increased in order to reduce the side wall curl.

• Geomechanics and Engineering
• /
• 제16권3호
• /
• pp.309-320
• /
• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• 한국콘텐츠학회논문지
• /
• 제18권1호
• /
• pp.441-451
• /
• 2018

이번 논문의 주요 관점은 코리올리힘(Corioli's force)의 원리와 손끝의 감각을 이용하여 고속회전(RPM)에 의해서 기벽 표면에 흠집을 내어 스트라이프(Stripe)의 질감(texture)을 안쪽에서 외벽으로 밀어 늘리는 방식과 코리올리힘(원심력)의 다변화된 아름답고 다이나믹한 독특한 외벽 질감 표현이 관건인데 이를 코리올리힘 기법이라고 정하였다. 또한 전통적인 옹기(onggi)의 평저굽(Flat Bottom Foot)성형 방식을 전기물레를 이용하여 빠른 회전력으로 원통 안쪽에서 밖으로 밀어 외벽을 늘림과 동시에 바닥의 밑면을 평평하게 굽을 펴는 새로운 방식의 평저굽을 개발하였는데 이러한 기법들을 융합하여 새롭고 현대적이면서 독특한 인테리어 작품을 만드는 것이 목적이다.

• Coupled systems mechanics
• /
• 제7권4호
• /
• pp.407-420
• /
• 2018

In solid-liquid two phase flow, the knowledge of how descending solid particles affected by the presence of downstream wall is important. This work studies at what interstitial distance the velocity of a vertically descending sphere is affected by a downstream wall as a consequence of wall-modified hydrodynamic forces through a validated dynamic model. This interstitial distance-the hydrodynamic coupling distance ${\delta}_c-is$ found to decay monotonically with the approach Stokes number St which compares the particle inertia to viscous drag characterized by the quasi-steady Stokes' drag. The scaling relation ${\delta}_c-St-1$ decays monotonically as literature below the value of St equal to 10. However, the faster diminishing rate is found above the threshold value from St=10-40. Furthermore, an empirical relation of ${\delta}_c-St$ shows dependence on the drop height which clearly indicates the non-negligible effect of unsteady hydrodynamic force components, namely the added mass force and the history force. Finally, we attempt a fitting relation which embedded the particle acceleration effect in the dependence of fitting constants on the diameter-scaled drop height.

• Nuclear Engineering and Technology
• /
• 제54권4호
• /
• pp.1495-1507
• /
• 2022

The improvement of thermal-hydraulic analysis techniques is essential to ensure the safety and reliability of nuclear power plants. The one-dimensional two-fluid model has been adopted in state-of-the-art thermal-hydraulic system codes. Current constitutive equations used in the system codes reach a mature level. Some exceptions are the partition method of wall friction in the momentum equation of the two-fluid model and the interfacial drag force model for a horizontal two-phase flow. This study is focused on deriving the partition method of wall friction in the momentum equation of the two-fluid model and modeling the interfacial drag force model for a horizontal bubbly flow. The one-dimensional momentum equation in the two-fluid model is derived from the local momentum equation. The derived one-dimensional momentum equation demonstrates that total wall friction should be apportioned to gas and liquid phases based on the phasic volume fraction, which is the same as that used in the SPACE code. The constitutive equations for the interfacial drag force are also identified. Based on the assessments, the Rassame-Hibiki correlation, Hibiki-Ishii correlation, Ishii-Zuber correlation, and Rassame-Hibiki correlation are recommended for computing the distribution parameter, interfacial area concentration, drag coefficient, and relative velocity covariance of a horizontal bubbly flow, respectively.