• Journal of Korea Foundry Society
• /
• v.25 no.6
• /
• pp.226-232
• /
• 2005

Contact material is widely used in the field of electrical parts. Ag-CdO material has a good wear resistance and stable contact resistance. In order to establish optimizing heat treatment condition, rolling temperature and oxidation process, we studied the microstructure of Ag-CdO material with various conditions. The experimental procedure were melting using high frequency induction, heat treatment, rolling and internal oxidation. And we experimented on difference process, Post-oxidaion. In this study, we obtained the optimizing heat treatment condition was $700^{\circ}C$ for 15 min. and the optimizing rolling temperature was $730^{\circ}C$. In investigation of the microstructure of oxidized material, coarse oxide and depleted oxidation layer existed. The hardness was average Hv 70. When we used Post-oxidation, oxides were finer than prior process and depleted oxidation layer did not exist. The hardness of Post-oxidation material was average Hv 80. And the optimizing rolling temperature was $800^{\circ}C$.

• Journal of the Korean institute of surface engineering
• /
• v.34 no.1
• /
• pp.56-61
• /
• 2001

In this work, the surface treatment of aluminum/composites (graphite-epoxy composites) was investigated. The surface of composites was treated by $Ar^{+}$ ion beam under oxygen environment. The surface of aluminum was treated by DC plasma. The optimal condition of surface treatment for the composites was determined by measuring the contact angle as a function of ion dose. The optimal treatment condition of the aluminum was determined by measuring the contact angle and T-peel strength as a function of mixture ratio of acetylene gas to nitrogen gas. The mixture ratios used were 1:9, 3:7, 5:5, 7:3, and 9:1. The results showed that the contact angle of composites decreased from$ 81^{\circ}$ to $8^{\circ}$ as the ion dose increased from zero to $1$\times$10^{17}$ions/$\textrm{cm}^2$. The optimal condition of ion dose was $1$\times$10^{16}$ions/$\textrm{cm}^2$. The results also showed that the contact angle of aluminum was a minimum for the mixture ratio of 5:5. Similarly, the T-peel strength was a maximum for the mixture ratio of 5:5, which indicates that the optimal condition of mixture ratio of acetylene gas to nitrogen gas is 5:5.

• KSTLE International Journal
• /
• v.1 no.1
• /
• pp.8-11
• /
• 2000

A surface crack in a semi-infinite body under Hertzian contact was considered. The simplified method used to estimate stress intensity factor K for specimen was extended to the model which is chosen in this paper. Very satisfactory results are obtained comparing with those known and it is proved that the method is more convenient than other methods. The results of the analysis show that due to the presence of $K_I$ for unlubricated condition, mode I fracture is active in the field below the surface and the maximum $K_{I}$ is obtained when the trailing edge of Hertzian contact reaches a position over the crack. The magnitudes of stress intensity factors $K_I$ and $K_Il$ increase with increasing friction forces. For a surface crack perpendicular to the contact surface, the stress intensity factor $K_I$ reaches its maximum value at a depth very close to the surface. Driving forve fer crack initiation and propagation is $K_I$ for unlubricated condition and $K_Il$ for both fluid and boundary lubricated condition.n.

• The Journal of the Society of Korean Medicine Diagnostics
• /
• v.17 no.3
• /
• pp.225-232
• /
• 2013

Objectives The aim of this study is to design a part in contact with the face of computerized tongue diagnosis system (CTDS), so that external light is effectively shielded even if the facial appearance and degree of protrusion differ when a patient opens or closes his/her jaws. Methods Each of the 4 researchers manually produced clay models of the part in contact with the face of CTDS. Shielding and contact feeling of the clay models were evaluated by 20 assessors. Based on the evaluation, we selected the appropriate model and produced the final silicon model. Then we evaluated the performance of the shielding of the completed silicon model. We took tongue pictures of 60 participants with a CTDS applying the silicon model in condition with external light and without it. The color values in RGB color model and gray scale of the tongue pictures in condition with external light were compared with those without external light. Results There was no significant difference between the color values of the picture taken in condition with external light and those without external light. Conclusions We concluded that the produced part in contact with the face of CTDS can effectively block out the external light.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.255-256
• /
• 2002

In this paper, the frictional behavior according to the contact geometry was investigated using a micro-tribotester built inside a Scanning Electron Microscope (SEM) and an Atomic Force Microscope (AFM). FFT (Fast Fourier Transform) analysis for friction was conducted as a method to interpret the contact condition. From the experimental results, it could be concluded that the relative dimensions and distribution of contact asperities on the surface could be predicted by the power spectrum and main frequency in the FFT analysis of the friction signal.

• Journal of Mechanical Science and Technology
• /
• v.19 no.11
• /
• pp.1967-1974
• /
• 2005

The subsurface stress field caused by both normal loads and tangential loads has been evaluated using the rectangular patch solution. The effect of tangential loading on the subsurface stress field has been investigated in detail for both the cylinder-on-cylinder contact and a spur gear teeth contact. For the cylinder-on-cylinder contact, the subsurface stress fields are moved more to the direction of tangential loads and the positions where the maximum stress occur are getting closer to the surface with the increasing tangential loads. The subsurface stress fields of the gear teeth contact are expanded more widely to the direction of tangential loads with the increasing tangential loads. The friction coefficient of a gear teeth contact is low because they are operated in a lubricated condition, and therefore surface tractions in the EHL condition hardly affect on the subsurface stress field.

• International Journal of Railway
• /
• v.2 no.4
• /
• pp.187-192
• /
• 2009

Running test of the Korean High-Speed Train using remote controlled measuring system have been executed on the high speed track in order to evaluate and verify the performance of the train. In this paper, influencing factors on the contact force which represents dynamic characteristics between the pantograph and contact wire are analyzed, according to the track condition, span type and running condition. By the analytical study on the test data, we figured out that contact force and dynamic characteristics of the pantograph are mainly affected by running behavior of the train and the span distance which the train passes.

• Tribology and Lubricants
• /
• v.16 no.4
• /
• pp.289-294
• /
• 2000

This paper present the contact stresses, which considers the shear stress at the cam and follower interface in the direct acting type valve train system of a high speed engine. To determine the contact condition, the normal contact forces are calculated by using the lumped mass dynamic modeling. The line contact is considered between the cam and follower interface. The variations of dynamic stresses are presented as a function of camshaft rotational angle. Also the effects of various design parameters are investigated.

• Communications of the Korean Mathematical Society
• /
• v.17 no.3
• /
• pp.519-529
• /
• 2002

In this paper. We Study (n + 1)-dimensional Contact CR-submanifolds of (n - 1) contact CR-dimension immersed in a Sasakian space form M$\^$2m+1/(c) (2m=n+p, p>0), and especially determine such submanifolds under additional condition concerning with shape operator.

• Tribology and Lubricants
• /
• v.18 no.2
• /
• pp.160-166
• /
• 2002

In case of rough contact fatigue, the accurate calculation of surface tractions is essential to the prediction of crack initiation life. Accurate Surface tractions influencing shear stress amplitude can be obtained by contact analysis based on the morphology of contact surfaces. In this study, to simulate rough contact under sliding condition, gaussian rough surface generated numerically in the previous study was used and to calculate clack initiation life in the substrate, dislocation pileup theory was used.