• 대한기계학회논문집B
• /
• 제30권4호
• /
• pp.381-388
• /
• 2006

The objective of this study is to predict the etching characteristics using spray characteristics for the optimization on the etching process of Lead-Frame. The etching characteristics such as etching factor, uniformity were investigated on the actual operating conditions. The correlation between the etching characteristics and the spray ones obtained by measurement were analyzed to simulate the etching characteristics according to actual conditions of lead-frame etching process. These conditions of lead-frame process were spray pressure, distance from nozzle tip to substrate, pipe pitch, and nozzle pitch. To improve the etching characteristics in the lead-frame process, effects of the various operating conditions should be understood in detail. The spray characteristics obtained by experiment using PDA system were simulated by the Monte-Carlo method. The etching process model was coded by Java language. It was found that simulation results generally agreed well with the measured results of etching characteristics in lead-frame etching process. The optimal operating parameters were successfully found under variable conditions.

• Structural Engineering and Mechanics
• /
• 제46권5호
• /
• pp.645-672
• /
• 2013

The differential settlements and rotations among footings cannot be avoided when the frame-footing-soil system is subjected to seismic/dynamic loading. Also, there may be a situation where column(s) of a building are located near adjoining property line causes eccentric loading on foundation system. The strap beams may be provided to control the rotation of the footings within permissible limits caused due to such eccentric loading. In the present work, the seismic interaction analysis of a three-bay three-storey, space frame-footing-strap beam-soil system is carried out to investigate the interaction behavior using finite element software (ANSYS). The RCC structure and their foundation are assumed to behave in linear manner while the supporting soil mass is treated as nonlinear elastic material. The seismic interaction analyses of space frame-isolated footing-soil and space frame-strap footing-soil systems are carried out to evaluate the forces in the columns. The results indicate that the bending moments of very high magnitude are induced at column bases resting on eccentric footing of frame-isolated footing-soil interaction system. However, use of strap beams controls these moments quite effectively. The soil-structure interaction effect causes significant redistribution of column forces compared to non-interaction analysis. The axial forces in the columns are distributed more uniformly when the interaction effects are considered in the analysis.

• International Journal of Concrete Structures and Materials
• /
• 제10권4호
• /
• pp.479-497
• /
• 2016

Many experimental studies have evaluated the in-plane behavior of reinforced concrete frames in order to understand mechanisms that resist progressive collapse. The effects of transverse beams, frames and slabs often are neglected due to their probable complexities. In the present study, an experimental and numerical assessment is performed to investigate the effects of transverse beams on the collapse behavior of reinforced concrete frames. Tests were undertaken on a 3/10-scale reinforced concrete sub-assemblage, consisting of a double-span beam and two end columns within the frame plane connected to a transverse frame at the middle joint. The specimen was placed under a monotonic vertical load to simulate the progressive collapse of the frame. Alternative load paths, mechanism of formation and development of cracks and major resistance mechanisms were compared with a two-dimensional scaled specimen without a transverse beam. The results demonstrate a general enhancement in resistance mechanisms with a considerable emphasis on the flexural capacity of the transverse beam. Additionally, the role of the transverse beam in restraining the rotation of the middle joint was evident, which in turn leads to more ductile behavior. A macro-model was also developed to further investigate progressive collapse in three dimensions. Along with the validated numerical model, a parametric study was undertaken to investigate the effects of the removed column location and beam section details on the progressive collapse behavior.

• Korea-Australia Rheology Journal
• /
• 제18권4호
• /
• pp.171-181
• /
• 2006

We present a short review for authors' previous work on direct numerical simulations for inertialess hard particle suspensions formulated either with a Newtonian fluid or with viscoelastic polymeric fluids to understand the microstructural evolution and the bulk material behavior. We employ two well-defined bi-periodic domain concepts such that a single cell problem with a small number of particles may represent a large number of repeated structures: one is the sliding bi-periodic frame for simple shear flow and the other is the extensional bi-periodic frame for planar elongational flow. For implicit treatment of hydrodynamic interaction between particle and fluid, we use the finite-element/fictitious-domain method similar to the distributed Lagrangian multiplier (DLM) method together with the rigid ring description. The bi-periodic boundary conditions can be effectively incorportated as constraint equations and implemented by Lagrangian multipliers. The bulk stress can be evaluated by simple boundary integrals of stresslets on the particle boundary in such formulations. Some 2-D example results are presented to show effects of the solid fraction and the particle configuration on the shear and elongational viscosity along with the micro-structural evolution for both particles and fluid. Effects of the fluid elasticity has been also presented.

• 대한기계학회논문집A
• /
• 제37권9호
• /
• pp.1077-1082
• /
• 2013

경기력 향상을 위한 자전거 프레임을 제작하기 위하여 주행 시 자전거 프레임에 발생하는 항력을 고려한 공기역학적 설계가 필요하다. 이를 위해 국제 사이클연맹 규격에 맞추어 초기 프레임을 설계 및 제작을 하였고 프레임에 발생하는 항력을 정량적 척도로 판단하기 위하여 항력계수를 이용하였다. 자전거 프레임의 공기저항을 최소화하기 위해 프레임 단면의 파라미터 설계를 실시하여 최적의 프레임의 형상을 도출하였다. 또한 자전거 프레임은 주행 시 선수에 의한 하중을 견딜 수 있어야 한다. 구조적인 측면에서 안정성을 갖춘 프레임을 제작하기 위하여 국제 사이클 연맹규격에서 제시하는 하중조건을 근거로 프레임의 강성을 평가하였고 이를 통해 선수용 자전거 프레임을 개발하였다.

• 생물환경조절학회지
• /
• 제8권3호
• /
• pp.202-208
• /
• 1999

김과 이(1997, 1998a, 1998b)가 개발한 컴퓨터 시뮬레이션 모형을 이용하여 온실의 골조율과 동길이가 직달일사 및 산란일사 투과율에 미치는 영향을 분석한 결과를 요약하면 다음과 같다. 글조율의 증가에 따라 산란일사 투과율이 조금씩 감소하였으나, 산란일사 투과율에 미치는 골조율의 영향은 작게 나타났다. 동일한 골조율에서 산란일사 투과율에 미치는 동수의 영향은 거의 없는 것으로 나타났다. 단동 또는 연동온실의 기본 골조물을 14.9%로 설정하였을 때 11.3%의 골조율에서 직달일사 투과율은 약 1.5∼3.0% 증가하였으며, 골조율이 18.3%일 때에는 1. 5∼3.0% 낮게 나타났다. 연동 온실에서 골조율의 증가 또는 감소가 직달일사 투과율에 미치는 효과는 동서동과 남북동 온실에서 유사하게 나타났다. 직달일사 투과율의 차이가 동계에 온실내의 식물 생육에 미치는 영향이 크기 때문에, 온실을 설계할 때 구조물의 안전이 유지되는 범위 내에서 내구력을 지닌 경량의 구조재를 사용하여 일사 투과를 각 대화시키는 것이 바람직하다 한편, 동길이가 24.5m 이상인 경우 동서동 또는 남북동에서 직달일사 투과율에 미치는 동길이의 영향은 거의 없는 것으로 나타났다.

• Structural Engineering and Mechanics
• /
• 제10권5호
• /
• pp.479-489
• /
• 2000

Based on the stiffness equation of the tapered beam element involving the effects of axial force and shear deformation, numerical investigations are carried out on elastic instability for web-linearly tapered columns with I-section of steel portal frames. Effects of shear deformation on the effective length of the tapered columns with I-section are studied. An efficient approach for determining the effective length of the tapered portal frame columns considering effects of shear deformation is proposed.

• Earthquakes and Structures
• /
• 제16권4호
• /
• pp.425-436
• /
• 2019

Successive ground motions having short time intervals have occurred in many earthquakes so far. It is necessary to investigate the effects of this phenomenon on different types of structures and to take these effects into consideration while designing or retrofitting structures. The effects of seismic sequences on the structures with combined reinforced concrete shear wall and moment resisting frame system have not been investigated in details yet. This paper has tried to analyse the seismic performance of structures with such structural systems subjected to mainshock-aftershock sequences. The effects of the seismic sequences on the investigated models are evaluated by strong measures such as IDA capacity and fragility and vulnerability curves. The results of this study show that the seismic sequences have a significant effect on the investigated models, which necessitates considering this effect on designing, retrofitting, decision making, and taking precautions.

• 인지과학
• /
• 제24권2호
• /
• pp.173-201
• /
• 2013

한국의 대학생을 대상으로 문화성향(개인주의-집단주의, 또는 수평적-수직적 사고)과 종결욕구 수준(저-고집단)의 조합에 따른 틀효과에서의 차이를 살펴보았다. 이를 위해 Singelis 등[1]의 INDCOL 척도와 이성수[2]의 NFC 척도를 사용하여 문화성향과 종결욕구 수준에 따라 집단을 분류한 후, 다섯 가지의 의사결정 시나리오에 대한 위험추구와 위험회피의 틀효과 차이를 비교하였다. 본 연구의 결과를 요약하면 다음과 같다. (1) 이득틀 조건에서는 위험회피 대안의 선택 비율이, 반면 손실틀 조건에서는 위험추구 대안의 선택 비율이 상대적으로 더 높았다. (2) 두 가지 문화성향(개인주의-집단주의, 수평적-수직적 사고성향)에 따른 틀효과 차이는 각각 유의하지 않았으나, 종결욕구가 높은 집단은 종결욕구가 낮은 집단에 비해 손실틀 조건에서 위험추구 대안에 대해 상대적으로 더 높은 선호도를 보였다. 마지막으로 (3) 개인주의 문화성향과 수평적 사고성향에서는 종결욕구 수준에 따른 틀효과 차이가 유의하지 않았으나, 집단주의 문화성향과 수직적 사고성향에서는 종결욕구 수준에 따른 틀효과의 차이가 유의하였다. 즉, 틀효과에 대한 집단주의 문화성향과 수직적 사고성향의 영향은 종결욕구 수준이 낮은 집단보다는 높은 집단에서만 관찰되었다.

• 국제초고층학회논문집
• /
• 제6권1호
• /
• pp.1-9
• /
• 2017

The Pertamina Energy Tower (PET) and Manhattan West North Tower (MWNT) are two supertall towers recently designed and engineered by Skidmore, Owings & Merrill (SOM). The structural system for both buildings consists of an interior reinforced concrete core and a perimeter moment frame system, which is primarily structural steel. As is typical for tall towers with both concrete and steel elements, staged construction analysis was performed in order to account for the long term effects of creep and shrinkage, which result in differential shortening between the interior concrete core and steel perimeter frame. The particular design of each tower represents two extremes of behavior; PET has a robust connection between the perimeter and core in the form of three sets of outriggers, while the perimeter columns of MWNT do not reach the ground, but are transferred to the core above the base. This paper will present a comparison of the techniques used during the analysis and construction stages of the design process with the goal of understanding the differences in structural behavior of these two building systems in response to the long term effects of creep and shrinkage. This paper will also discuss the design and construction techniques implemented in order to minimize the differential shortening between the interior and exterior over the lifespan of these towers.