• 한국안광학회지
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• 제10권2호
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• pp.127-132
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• 2005

칼라콘택트렌즈는 의료용으로 사용되기 시작하여 최근 들어 미용의 목적으로 그 수요가 급격히 증가하고 있는 추세이다. 칼라콘택트렌즈의 제조방법으로는 pigment application method, pigment inlay method, sandwich method, binding method 등이 있는데 현재 국내에서는 binding method가 주로 사용된다. 칼라 콘택트렌즈의 용도와 제조 방법 면에서 채색(tinted)과 착색(cosmetic)으로 크게 분류되는데 채색은 염색방식으로 널리 알려진 방법이며, 착색은 박막공법에 의해 제조된다. 이에 따라 본 해설의 목적은 칼라콘택트렌즈의 제조방법 및 방법에 따른 특성을 비교하고, 칼라콘택트렌즈의 특성을 이해하는데 도움을 주기 위함이다.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1631-1637
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• 2002

This paper presents a method for calculating contact force between bodies on plane. At each integration time step, the proposed method finds expected contact point on their outlines and then calculates penetration, velocity of penetration and contact force. This paper adopts continuous analysis method and multi-point contact method to calculate contact force. To obtain the accurate expected contact point on their outlines, a new algorithm is developed. The accuracy of the proposed algorithm is demonstrated by comparing the numerical results of the proposed method and DADS.

• 한국전산구조공학회논문집
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• 제22권5호
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• pp.439-444
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• 2009

본 논문에서는 경계요소법의 평면 접촉해석에 사용될 수 있는 효율적인 접촉면 검출 알고리즘을 제시하였다. 접촉면 검출 알고리즘을 경계요소법에 적용하기 위하여, 경계요소법이 가지는 자료구조를 분석하였다. 경계요소법의 특징 중 하나인 모퉁이 문제를 고려하여 전역검색, 지역검색, 접촉관계식 설정의 3단계로 접촉면 검출기법을 구현하였다. 전역검색은 접촉 주요소, 부요소 개념을 도입하였으며, 지역검색에 있어서는 공간분할기법인 사지트리를 이용하였다. 접촉관계식의 설정을 위하여 요소수준에서 절점의 접촉여부를 검토하고 최종계의 방정식에 구속조건을 할당하도록 하였다. 제시된 알고리즘을 이용한 프로그램의 정확성과 효율성을 입증하기 위하여 수치해석을 실시하여 결과를 비교하였다.

• Tribology and Lubricants
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• 제31권4호
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• pp.163-169
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• 2015

This paper describes a design method for the corner radius of a contacting body using the theoretical approach of contact mechanics. A complete contact, as in the case of a sharp-cornered punch, produces singular contact traction: whereas, in an incomplete contact, the singular contact traction disappears because of the rounded corners, and the contact edges are within the rounded regions. The design method aims to determine the conditions of the contact force as well as the material properties in an incomplete contact. The incomplete contact changes into the complete contact again when the contact edges exceed the rounded regions owing to either an increased contact force or the compliance of the materials. The contact length of a rounded punch is used as a parameter to derive the required conditions. As a result, a design formula is obtained, which provides a minimum allowable radius when the materials, normal contact force, and the length of a flat region of the punch are predetermined. This work consists of two parts: Part I includes a theoretical background, design method, and formula, and Part II describes the actual process with the investigation of design parameters.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.281-285
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• 2002

A new method of dynamic contact force measurement between a pantograph and a contact wire is proposed in this paper The method does not require design modification of an original pantograph in order to install sensors such as load cells. Contact forces can be expressed as the sum of vertical shear forces at the support points and inertial forces. Using specially-designed strain gage rosettes. vertical shear forces at the supported points can be measured without noise mixing and thermal effects. In order to obtain contact forces from shear forces, 3 inertial force compansation methods are proposed and compared in this paper. By validation process, the new proposed measurement method is verified to be applicable to the on-line current collection test.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.84-87
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• 2009

Electrowetting is a versatile tool to handle tiny droplets and forms a backbone of digital microfluidics. Numerical analysis is necessary to fully understand the dynamics of electrowetting, especially in designing electrowetting-based devices, such as liquid lenses and reflective displays. We developed a numerical method to analyze the general contact-line problems, incorporating dynamic contact angle models. The method is based on the conservative level set method to capture the interface of two fluids without loss of mass. We applied the method to the analysis of spreading process of a sessile droplet for step input voltages and oscillation of the droplet for alternating input voltages in electrowetting. The result was compared with experimental data. It is shown that contact line friction significantly affects the contact line motion and the oscillation amplitude. The pinning process of contact line was well represented by including the hysteresis effect in the contact angle models.

• 보건교육건강증진학회지
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• 제4권1호
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• pp.65-75
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• 1987

This study was conducted (i) to recommend the high-scored education method as a adaptable method, and (ii) to find the most influential factor among the three acceptability components (feasibility factor, stimulation factor and reliability factor) to urban or rural residents. The accept-ability score of each health education method currently existing in urban and rural area was estimated. A total of 257 households in Guro 6-dong, Seoul, and 233 households in Jeomdong-myeon, Yeoju-gun, were sampled by interview survey using questionnaire. The four types of health education methods used in this study are; printed matter method, mailing service method. personal contact method, and group contact method. The major findings obtained from this research are as follows; 1) In urban area, the highest-scored in terms of acceptability is the personal contact method, followed by the mailing service, the printed matter, and the group contact. The mailing service method is found to be effective especially for the intelligent group people. 2) In rural area, the highest-scored in terms of acceptability is also the personal contact method, followed by the group contact, and printed matter method. In general, the group contact method is effective toward both urban-poor and rural housewives (especially in stimulation factor). To improve the health consciousness of the residents, there arises the need for the existing education program into better organized and diversified one and for educating health-educators by providing in-depth health knowledge.

• 한국공작기계학회논문집
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• 제16권3호
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• pp.75-80
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• 2007

It is necessary to analyze the contact phenomena in order to effectively design the machine components with contact surfaces. In general, the contact action is highly nonlinear and irreversible because we cannot predict the contact regions and conditions. Recently, the finite element method is used to analyze the contact problem. In this paper, the contact element method is applied to avoid the mesh refinement and iterative calculation of general contact algorithms. By use of it, the deformation and stress concentration of turbo compressor rotor are computed. It shown that the contact element is convenient analysis and the results are relatively accurate.

• 대한기계학회논문집
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• 제17권7호
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• pp.1658-1667
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• 1993

In this research, a numerical algorithm has been developed, which can be applied to the large deformation and large displacement contact problems between two deformable bodies. The contact conditions expressed in terms of the rate of angle change have been proposed considering the change in geometric shape and rate of contact force. A set of linear simultaneous equations is constructed by adding the geometric shape change and contact conditions to the original stiffness matrix. A new method to determine time increment has been proposed based on Euler method, in which the condition to prevent the contact bodies from penetrating and overrunning each other has been taken into consideration. Practical application to contact problem is extrusion in which bodies are sliding along the contact boundary.

• Structural Engineering and Mechanics
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• 제24권2호
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• pp.155-180
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• 2006

Many applications in mechanical design involve elastic bodies coming into contact under the action of the applied load. The distribution of the contact pressure throughout the contact interface plays an important role in the performance of the contact system. In many applications, it is desirable to minimize the maximum contact pressure or to have an approximately uniform contact pressure distribution. Such requirements can be attained through a proper design of the initial surfaces of the contacting bodies. This problem involves a combination of two disciplines, contact mechanics and shape optimization. Therefore, the objective of the present paper is to develop an integrated procedure capable of evaluating the optimal shape of contacting bodies. The adaptive incremental convex programming method is adopted to solve the contact problem, while the augmented Lagrange multiplier method is used to control the shape optimization procedure. Further, to accommodate the manufacturing requirements, surface parameterization is considered. The proposed procedure is applied to a couple of problems, with different geometry and boundary conditions, to demonstrate the efficiency and versatility of the proposed procedure.