• Tribology and Lubricants
• /
• 제5권1호
• /
• pp.28-35
• /
• 1989

The wear tests of ceramic materials in dry rolling contact were carried out at room temperature to investigate their macroscopic wear characteristics. Both point contact and line cootact were adapted in the wear tests of them. Ceramic materials used in these tests were silicon nitride, silicon carbide, cermet of TiN and TiC, titania, and alumina. The wear test of the bearing steel was carried out to compare to the wear test results of the ceramic materials. The results showed that the wear rate of silicon nitride was smaller than any other ceramic materials and bearing steel. In the steady wear, the wear volume of ceramic materials increases linearly with the rolling distance. It was also found from the experimental results that fracture toughness and surface roughness dominate the wear process of ceramic materials in dry rolling contact.

• E2M - 전기 전자와 첨단 소재
• /
• 제8권2호
• /
• pp.136-143
• /
• 1995

With the contact angle of phase dropping epoxy resin on the inorganic filler(glass plate) surface treated with air plasma, we have studied about the interfacial wettability between epoxy resin and glass plate as a simple model of glass fiber reinforced composite materials. The contact angle on the inorganic filler surface varied with surface treatment conditions. The contact angle significantly depends on plasma treating time and environment temperature in the oven. From the view point of plasma treatment condition in this work, when discharge conditions were pressure 200mtorr, voltage 800V, magnetic flux density 8OGauss, optimum treatment time were proved as 3,4 and 5 minutes for the environment of >$80^{\circ}C$, >$100^{\circ}C$ and >$120^{\circ}C$, respectively.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 1999년도 춘계학술대회 논문집
• /
• pp.151-158
• /
• 1999

In this study, we developed the simulation program of an overhead catenary-pantograph system, The overhead catenary is modeled with point mass and the pantograph is replaced with 3 d. o. f. model which is composed of mass, spring and damper. Using the developed program, we analyzed the static structure of the overhead catenary and the dynamic characteristics of an overhead catenary-pantograph system such as uplift displacement of contact wire and contact force. we compared the analysis results with the results of GASENDO software developed at RTRI in Japan. The behaviors of uplift displacement of contact wire and contact force were similar with the results of GASENDO software.

• 한국공작기계학회논문집
• /
• 제12권5호
• /
• pp.24-33
• /
• 2003

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of transmission contact element using 2-dimension model considered near the tooth by root stress. Determination of root stress is carried out far the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. The predicted results of boundary element method are good accordance with that of finite element method.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
• /
• pp.293-300
• /
• 1999

A mathematical model for the analysis of roll gap phenomena in strip temper rolling process is described. The mechanical peculiarities of temper rolling process, such as high friction value and non-circular contact arc, low reduction and non-negligible entry and exit elastic zones as well as central restricted deformation (preliminary displacement or sticking) zone etc., are all taken into account. The deformation of work rolls is calculated with the influence function method and arbitrary contact arc shape is permitted. The strip deformation is modeled by slab method and the entry and exit elastic deformation zones are included. The restricted deformation zone near the neutral point is also considered. The concept and the calculation method of limiting preliminary displacement are used to determine the length of the central restricted deformation zone. The comparison of the model results with the measured mill data is also made.

• 한국중재학회지:중재연구
• /
• 제27권4호
• /
• pp.179-198
• /
• 2017

The OECD Guidelines for Multinational Enterprises (The Guidelines) was initially promulgated in 1976 as a form of annex to the OECD Declaration on International Investment and Multinational Enterprises. The Guidelines aims at accomplishing the implementation and dissemination of the Responsible Business Conduct. The latest version of The Guidelines, as revised in 2011, directed 47 adhering countries to The Guidelines to set up their respective National Contact Points (NCPs). NCPs are The Guidelines' dispute resolution mechanism for specific instances arising from breach by multinational enterprises of The Guidelines. Korea to date has its own NCP performing its role to offer good offices and facilitates settlement between the parties to the specific instances regarding The Guidelines. However, there has been strong criticism from NGOs and civil society that Korea NCP has not performed well due to lack of transparency and impartiality, especially in the context of the governance of Korea NCP. Under this circumstance, this paper ⅰ) examines current status and problems of Korea NCP, ⅱ) evaluates the core criteria for function and governance of NCPs through a comparative overseas cases study, and ⅲ) suggests improvement plans for Korea NCP.

• 한국정밀공학회지
• /
• 제16권7호
• /
• pp.203-209
• /
• 1999

In this paper, we present the methods to predict the milled surface shapes in profile milling process. In the cutting process, tools are deflected due to the cutting forces varying with the imposed depth of cut and feedrate. Thus, the final shapes of the milled surface, generated by the nominal tool trajectory, are different from the required profile. In order to predict the milled surface shapes, we present two methods based on: (1) the deflected tool profile and (2) the trace of contact point between the tool and the workpiece. In the first method, we make an assumption that the milled surface corresponds to the deflected tool profile. In another method, we make we make an assumption that the milled surface is generated by the trace of the contact point between the cutting edge of the tool and workpiece. We present the surface generation process by calculating the trajectory of the contact points on the workpiece. Several simulations and experiments are performed to verify the proposed milled surface prediction methods.

• 한국정밀공학회지
• /
• 제19권8호
• /
• pp.47-54
• /
• 2002

A barrel cam is used as a very important part of an index drive unit. The index drive unit must have an intermittent-rotational motion. The barrel typed cam and roller gear mechanism has the advantages of high reliability to perform a prescribed motion of a follower. This paper proposes a new method for the shape design of the barrel cam and also a CAD program is developed by using the proposed method. As defined in this paper, the relative velocity method for the shape design calculates the relative velocity of the follower versus cam at a center of roller, and then determines a contact point by using the geometric relationships and the kinematic constraints, where the direction of the relative velocity must be parallel to a common tangential line at the contact point of two independent bodies, i.e. the cam and the follower Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. This paper presents two examples for the shape design of the barrel cam in order to prove the accuracy of the proposed methods.

• 한국기계가공학회지
• /
• 제16권1호
• /
• pp.51-57
• /
• 2017

In the present study, the long-pitch roller-chain of a continuous ship unloader is studied. It is the vertical excavating and transporting the cargo has carried in bulk amount. The size of the pitch in the long-pitch roller chain is about 350 mm. The finite element technique is used for the structural safety of the roller chain. The objective of the study is to perform a dynamic analysis of the load at the point of contact with the sprocket of the roller chain, and analyze each point in the stress of the chain's components by using load. From the tooth sprocket optimization analysis, the results show an optimal design. Static structural analysis was safe. Contact analysis results show the greatest stress on the sprocket. By increasing the tooth size, the stress was reduced.

• 한국전기전자재료학회논문지
• /
• 제21권5호
• /
• pp.486-491
• /
• 2008

The plasma processing is applied to many industrial fields as thin film deposition or surface treatment technique. In this study, we investigated large-area uniformed surface treatment of PET film at low temperature by using Scanning Plasma Method(SPM). Then, we measured difference and distribution of temperature on film's surface by setting up a thermometer. We studied the condition of plasma for surface treatment by examining intensity of irradiation of uniformed plasma. And we compared contact angles of treated PET film by using Ar and $O_2$ plasma based low temperature. In our result, surface temperature of 3-point of treating is low temperature about $22^{\circ}C$, in other hands, there is scarcely any variation of temperature on film's surface. And by using Ar plasma treatment, contact angle is lower than untreatment or $O_2$ plasma treatment. In case of PET film having thermal weak point, low temperature processing using SPM is undamaged method in film's surface and uniformly treated film's surface. As a result, Ar plasma surface treatment using SPM is suitable surface treatment method of PET film.