• 한국소음진동공학회논문집
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• 제20권4호
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• pp.355-360
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• 2010

In this study, a modeling process of a 3-axis planar alignment stage is suggested. Vibration tests using a laser vibro-meter is performed to find the modeling parameters of the stage. By analyzing the result of the test, the stiffness of prismatic joints and revolute joints, as well as the contact conditions of the thrust bearings, can be calculated. The modeling of the stage was validated by comparing six normal mode shapes, which are acquired from experiments and simulations.

• 한국건축시공학회지
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• 제16권4호
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• pp.341-348
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• 2016

이 연구에서는 폭발원점으로부터 보호시설의 결정적 피해경감을 위해 설치되는 방호벽의 설계요구조건을 제안한다. 이를 위하여 일부지역에 구축된 방호벽과 관련한 현장조사 및 설계도서 검토를 수행한다. 규명된 방호벽 제원을 바탕으로 구조해석에 사용될 방호벽을 모델링하고, 방호벽에 대한 실질적인 위협을 판단한다. 구조 모델링 및 폭발위협 분석이 완료되면, 방호벽 및 보호시설의 손상정도를 충격, 관입, 파쇄 및 폭압효과 측면에서 수치해석을 통해 계산한다. 해석결과에 따르면, 방호벽의 두께는 최소 45cm 이상이어야 하며, 현재 설치된 방호벽은 단면증설을 통해 구조보강이 필요한 것으로 나타났다.

• Journal of Computational Design and Engineering
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• 제1권1호
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• pp.27-36
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• 2014

Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors affecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteristics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufacturability (and its limitation in logarithmic spiral bevel gears) is analyzed using precision forging and multiaxis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multiaxis freeform milling also need to be solved in a further study.

• 한국측량학회지
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• 제24권1호
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• pp.1-8
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• 2006

효율적인 3차원 모델링은 건설, 기계 그리고 디자인과 같은 폭넓은 설계분야에서 필수적으로 되고 있다. 특히, 역설계를 가능케 하는 툴로써 발전하고 있다. 3차원 모델링은 신속성, 정확성 그리고 명확성이 요구된다. 모델링을 위한 데이터 획득은 접촉식 좌표측정기, 레이져스캐너, 패턴스캐너 그리고 수치사진측량방법을 이용한다. 본 연구에서는 모델링 기법을 분석하고 패턴스캐너를 이용한 3차원 모델링기법을 소개하고자 한다. 또한, 본 연구는 OPTO-Top 패턴스캐너를 이용하여 3차원 모델링을 시도하고 신속성과 효율성을 수치사진측량기법과 비교분석하였다. 아울러 3차원으로 사용자가 웹환경에서 시뮬레이션 할 수 있는 환경구축을 시도하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1992년도 춘계학술대회 논문집 92
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• pp.115-130
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• 1992

The analysis of thermoplastic automotive bumpers needs not only characterizations of the thermomechanical properties of thermoplastic materials but also the finite element method which can solve the problems with a large deflection, an elastic-inelastic deformation, and a change of a contact state. This paper describes the modeling techniques in the finite element analysis in order to get a good prediction of thermoplastic bumper behaviors. Simplification effects of a complex geometry of thermoplastic bumpers are studied by comparing the results from static loading tests and the finite element analysis.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.489-494
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• 2001

This paper deals with a dynamic modeling of artillery system loaded by gun charge explosion during firing condition. Geometric and elastic gun data are used to modify a projectile interaction model. The maximum impact force on gun barrel was 15,000 N and the gun barrel moved about 1.3 m. A cannon bal] was presented to travel in the flexible gun, the traveling distance was about 23,000 m, and the angular velocity was about 10rad/sec. The artillery dynamic system using the multi-body dynamics enables us to obtain the data for the fatigue analysis.

• 한국항공우주학회지
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• 제30권2호
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• pp.108-114
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• 2002

본 연구에서는 KSR-Ⅲ 로켓의 날개-동체 조인트에 대한 비선형 유한요소해석을 수행하므로 적절한 설계 개선을 제시하였으며, 최종 설계의 검증을 위해 수행된 구조 시험 결과와 비교하여 해석의 타당성을 평가하였다. 날개-동체 조인트는 동체 프레임 상에 존재하는 체결 홈에 날개의 체결부가 끼워짐으로 연결되는 방식으로 설계되었다. 이 방식은 연결 구조물간의 하중 전달을 주로 구조물간의 접촉면을 통해 이루어지게 하며, 체결 볼트를 통해서는 구조물을 고정하되 전달 하중은 최소화하기 위한 것이다. 조인트 구조의 정확한 해석을 위해 연결 구조물간의 접촉 및 체결 볼트를 통한 하중 전달을 묘사할 수 있는 세심한 구조 모델링을 적용하였다. 해석 결과에 의해 제시된 설계 개선은 구조시험을 통해 안전성이 검증되었으며, 해석 및 시험 결과가 잘 일치하였다.

• Interaction and multiscale mechanics
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• 제5권4호
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• pp.399-405
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• 2012

A dissipative particle dynamics (DPD) simulation was presented to analyze surface wettability and contact angles of a droplet on a solid platform. The many-body DPD, capable of modeling vapor-liquid coexistence, was used to resolve the vapor-liquid interface of a droplet. We found a constant density inside a droplet with a transition along the droplet boundary where the density decreased rapidly. The contact angle of a droplet was extracted from the isosurfaces of the density generated by the marching cube and a spline interpolation of 2D cutting planes of the isosurfaces. A wide range of contact angles from $55^{\circ}$ to $165^{\circ}$ predicted by the normalized parameter ($|A_{SL}|/B_{SL}$) were reported. Droplet with the parameters $|A_{SL}|>5.84B{_{SL}}^{0.297}$ was found to be hydrophilic. If $|A_{SL}|$ was much smaller than $5.84B{_{SL}}^{0.297}$, the droplet was found to be superhydrophobic.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.607-612
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• 2004

Disc brake noise continues to be a major concern throughout the automotive industry despite efforts to reduce its occurrence. Eliminating vibrations during braking is an important task for both vehicle passenger comfort and reducing the overall environmental noise levels. There are several classes of disc brake noise, the major ones being squeal, judder, groan, and moan. In this study, analytical model for moan noise of rear disk brake is investigated. Modeling of the disc brake assembly to take account of the effect of different geometrical and contact parameters is studied through the use of multi-body model. The contact stiffness of the caliper and torque member plays an important role in controlling brake vibration. Therefore, a suitable material pair at the caliper/body contact has been made. An ADAMS model of a rear disc brake system was integrated with a flexible suspension trailng arm from MSC/NASTRAN. A fully non-linear dynamic simulatin of brake system behavior, containing rigid and flexible bodies, was performed for a Prescribed set of operating conditions. Simulation results were validated using data from vehicle experimental testing.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.115-123
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• 2007

In this paper, an analytical model is developed to describe the dynamic characteristics of a roller bearing. In order to obtain accurate dynamic response of roller bearing, each roller is modeled as a rigid body, which has radial and axial movement and rotational constraints. Beam element between outer race segments is used to consider flexibility of outer race. Beam deflection is calculated from beam forces and used for contact between roller and outer race. The efficient contact search kinematics and algorithms in the context of the compliance contact model are implemented to detect the interactions between roller and race for the sake of speedy and robust solutions. The numerical results are validated with another analysis results which are calculated using waviness condition. Increasing rollers, dynamic responses are compared with each other. In order to confirm dynamic behavior and nonlinear characteristic of roller bearing, Poincare map is used.