• Composites Research
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• 제36권3호
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• pp.141-153
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• 2023

본 리뷰 논문에서는 일반 접촉 역학 이론과 더불어 유기탄성체 마찰에 관한 이론 및 배경을 소개한다. 특히 Greenwood & Williamson 접촉 역학 이론을 확장하여 거친 표면을 자기-아핀(self-affine) 특성으로 고려한 접촉 역학 및 마찰의 수학적 모델을 제시한 Klüppel & Heinrich 이론을 중심으로 유기탄성체 복합재료의 마찰 거동에 대해 살펴본다. 자기-아핀 특성에 의한 노면의 멀티스케일 거칠기로 인해 미끄러짐 마찰 시 유기탄성체 복합재료는 다양한 주파수에 따른 동적 변형이 가해지며 이때 재료가 나타내는 점탄성이 마찰 거동에 주요한 영향을 미친다. 따라서 유기탄성체 복합재료의 비선형 점탄성을 고려하여 광범위한 주파수 영역에서의 점탄성 거동인 마스터커브를 구축하는 원리 및 방법을 제시하였다. 마지막으로 유기탄성체 복합재료 마찰 이론을 타이어 트레드 컴파운드와 노면 간의 마찰에 응용한 실험적 결과와 그 물리적 의미를 이론과 접목하여 설명하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.1103-1104
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• 2009

• 한국노년학
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• 제38권3호
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• pp.409-433
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• 2018

본 연구는 어린이가 일상에서 노인과의 접촉을 통해 노인에 대한 차별적 태도(Ageist attitude)를 완화할 수 있는지, 해당 태도의 개선방안을 탐색하였다. 명시적 태도(Explicit attitude)의 측정에 사용되는 자기보고식(Self-reported) 척도가 의식에서 여과된 수준의 편견만 반영하는 한계를 고려해, 내면의 차별적 인식을 나타내는 '암묵적 태도(Implicit attitude)'를 측정하였다. 명시적 태도 측정에는 웃는 얼굴 5점 척도를, 암묵적 태도 측정에는 어린이용 암묵적 연령 연합검사(Children Implicit Age-association Test)를 사용하였다. 서울 및 수도권 초등학교 4~6학년 초등학생 503명의 자료를 수집했으며 기술통계, 다항 및 서열 로지스틱 회귀분석 방법으로 분석하였다. 분석결과는 크게 세 가지로 요약된다. 첫째, 노인에 대한 어린이의 명시적 태도와 암묵적 태도의 예측요인이 달랐다. 이는 편견의 '표출'을 완화하는 요소를 이용해 '내적 편견'을 예측하고 개선하는 데는 한계가 있으며 따라서 암묵적 편견에 대한 별도의 접근이 필요함을 보여준다. 둘째, 어린이의 연령차별적 태도와 노인 접촉경험의 관계는 어린이와 노인의 관계특성, 그리고 접촉의 양적 측면과 질적 측면에 따라 다소 복잡한 관계를 보였다. 종합적으로 요약하면 노인을 많이 그리고 긴밀하게 만나는 아이들이 표면적으로 또는 내면적으로 연령차별적일 가능성이 낮았다. 마지막으로, 접촉질이 중요한 명시적 태도와 달리 암묵적 태도는 접촉량과 약한 관련을 보였으며, 접촉질과는 관계가 없었다. 이는 편견 완화에 접촉량보다는 질의 효과를 강조해온 집단 간 접촉이론(Intergroup contact theory)으로 설명되지 않는 결과로, 접촉의 암묵적 태도에 대한 영향을 전반적으로 검토하고 이론을 보완할 필요가 있다.

• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.685-692
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• 2001

This paper reports on the mixed lubrication characteristics between the cam and the tappet contact surface of direct acting type valve train systems. First, the dynamic characteristics are solved by using the lumped mass method to determine the load conditions at the contact point. Then, the minimum oil film thickness is calculated with consideration of elastohydrodynamic line contact theory and the friction force is obtained by using the mixed lubrication model which separates the hydrodynamic and the boundary friction. Finally, the average surface temperatures are calculated by using the flash temperature theory. The results show that, there are some peaks in the friction force due to the asperity contact friction, and flash temperature at the position of minimum oil film thickness. It is thought that there is a relationship between the surface temperature and cam surface wear, and therefore, the analysis on the worn cam profile has been performed.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.17-34
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• 2001

The frictionless contact problem for a layered composite which consists of two elastic layers having different elastic constants and heights resting on two simple supports is considered. The external load is applied to the layered composite through a rigid stamp. For values of the resultant compressive force P acting on the stamp vertically which are less than a critical value $P_{cr}$ and for small flexibility of the layered composite, the continuous contact along the layer - the layer and the stamp - the layered composite is maintained. However, if the flexibility of the layered composite increases and if tensile tractions are not allowed on the interface, for P > $P_{cr}$, a separation may be occurred between the stamp and the layered composite or two elastic layers interface along a certain finite region. The problem is formulated and solved for both cases by using Theory of Elasticity and Integral Transform Technique. Numerical results for $P_{cr}$, separation initiation distance, contact stresses, distances determining the separation area, and the vertical displacement in the separation zone between two elastic layers are given.

• Computers and Concrete
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• 제31권2호
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• pp.163-171
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• 2023

Face gear transmission is widely used in aerospace shunt-confluence transmission system. Tooth wear is one of the main factors affecting its bearing transmission performance. Furthermore, the installation errors of face gear are inevitable. In order to study the wear mechanism of face gear tooth surface with installation errors, based on tooth contact analysis numerical method and Archard wear theory, the UMESHMOTION subroutine in ABAQUS is developed.Combining with Arbitrary Lagrangian-Eulerian adaptive mesh technology, the finite element mesh wear model of abraded face gear pair is established.The preprocessing conditions are set to generate the inp files.Then,the inp files for each corner are imported and batch processed in ABAQUS.The loading tooth contact problem at each rotation angle is solved and the load distribution coefficient among gear tooth, tooth root bending stress, tooth surface contact stress and loaded transmission error are obtained. Results show that the tooth root wear is the most serious and the wear at the pitch cone is close to 0.The wear law of tooth surface along tooth width direction is convex parabola and the wear law along tooth height direction is concave parabola.

• 대한음성학회:학술대회논문집
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• 대한음성학회 1996년도 10월 학술대회지
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• pp.176-181
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• 1996

This paper investigates patterns of manner assimilation in Toba Batak, Sanskrit, Ponapean and Korean. Based on cross-linguistic patterns of manner assimilation, I develop the constraint, Syllable Contact (SyllCon), as a type of a markedness constraint in Correspondence Theory. With the establishment of high-ranking SyllCon, I argue that several patterns of manner assimilation result from the interaction of high-ranking SyllCon and correspondence constraints such as Ident[sonorant].

• Structural Engineering and Mechanics
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• 제64권4호
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• pp.505-513
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• 2017

In this paper, a receding contact problem for an elastic layer resting on a half plane is considered. The layer is pressed by two rectangular stamps placed symmetrically. It is assumed that the contact surfaces are frictionless and only compressive traction can be transmitted through the contact surfaces. In addition the effect of body forces is neglected. Firstly, the problem is solved analytically based on theory of elasticity. In this solution, the problem is reduced into a system of singular integral equations in which half contact length and contact pressures are unknowns using boundary conditions and integral transform techniques. This system is solved numerically using Gauss-Jacobi integral formulation. Secondly, two dimensional finite element analysis of the problem is carried out using ANSYS. The dimensionless quantities for the contact length and the contact pressures are calculated under various stamp size, stamp position and material properties using both solutions. The analytic results are verified by comparison with finite element results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.154-159
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• 1995

To achieve a high aspect ration of metal contact, buried contact solar cell scribe the silicon surface using laser. The Q-switched NdLYAG laser which has 1.064$\mu\textrm{m}$ wavelength use for silicon scribing with 25~40$\mu\textrm{m}$ width and 20~200$\mu\textrm{m}$ depth capabilities. The 2~3% shading losses are very low campared to the screen printing solar cell. In this paper, we investigate the silicon scribing theory and pratice, scribing system for BCSC processing.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.139-142
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• 1996

This paper presents a method of controlling contact force for deburring tasks. The cope with the nonlinearities and time-varying properties of the robot and the environment, a neural network control theory is applied to design the contact force control system. We show that the contact force between the hand and the contacting surface can be controlled by adjusting the command velocity of a robot hand, which is accomplished by the modeling of a robot and the environment as Mass-Spring-Damper system. Simulation results are shown.