• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05b
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• pp.26-27
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• 1992

The effect of activation and electroless nickel plating conditions on contact properties were investigated for selective electroless nickel plating of Si farers in order to obtain an optimum condition of contact hole filling. According to RCA prosess, p-type si 1 icon (100) surface was cleaned out and activated. The effects of temperture, DMAB concentration, time, and stirring iwere investigated for activation of p-type Si(100) surface. The optimal activation condition obtained was 0.5M HF, 1mM PdCl$_2$, 2mM EDTA, 7$0^{\circ}C$, 90sec under ultrasonic vibration. In electroless nickel plating, the effect of temperature, DMAB concentration, pH, and plating ti me were studied. The optimal plating condition found was 0. 10M NiS0$_4$.$H_2O$, 0.lIM Citrate, pH 6.8, 6$0^{\circ}C$, 30 minutes. The contact resistence of fi]ms wascomparatively low. It took 30 minutes to obtain 1$\mu$m thick film with 8$\mu$M DMAB concentration. The film surface roughness was improved with increasing temperature and decreasing pH of the plating solution. The best quality of the film was obtained with the condition of temperature 6$0^{\circ}C$ and pH 6.8. The micro-victors hardness of film was about 600Hv and was decreased wi th increasing particle size of plating layer.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.624-635
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• 1990

Analytical study based on linear fracture mechanics was conducted on propagation behavior of inclined surface crack in semi-infinite elastic body. The analytical model was assumed to be inclined surface crack under plane strain condition upon which Hertzian stress was superimposed. Supposing continuous distribution of dislocation and applying Erdogan-Gupta's method to this crack problem, the stress intensity factors $K_{I}$ and $K_{II}$) at the crack-tip were obtained for various Hertzian contact positions. Analytic results have shown that driving force for crack growth is $K_{I}$ for non-lubricated condition and $K_{II}$ for fluid and boundary lubricated condition. The coefficient of friction at the hertzian contact and crack surfaces plays an important role in predicting the direction of crack propagation. It is also found that the maximum effective stress intensity factor exists at cracks of a certain specific length depending on lubricated condition.ion.n.

• Tribology and Lubricants
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• v.36 no.3
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• pp.147-152
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• 2020

This paper is within the framework of an adhered complete contact problem wherein the contact between a half plane and sharp edged indenter, both of which are elastic in character, is constituted. The eigensolutions of the contact shear and normal stresses, σ_rq and σ_q, respectively, are evaluated via asymptotic analysis. The ratio of σ_rq/σ_qq is investigated and compared with the coefficient of friction, μ, of the contact surface to observe the propensity to slip on the contact surface. Interestingly, there exists a region of |σ_rθ/σ_θθ| ≥ |μ|. Thus, slipping can occur, although the problem is solved under the condition of an adhered contact without slipping. Given that a tribological failure potentially occurs at the slipping region, it is important to determine the size of the slipping region. This aspect is also factored in the paper. A simple example of the adhered contact between two elastically dissimilar squares is considered. Finite element analysis is used to evaluate generalized stress intensity factors. Furthermore, it is repeatedly observed that slipping occurs on the contact surface although the size of it is extremely small compared with that of the contacting squares. Therefore, as a contribution to the field of contact mechanics, this problem must be further explained logically.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.47-54
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• 2006

In this study, an optimum support design problem is considered to minimize displacement of stacked plates under self weight condition. During the displacement analysis, several kinds of contact arise between the plates themselves and support bar. These can be easily considered if commercial analysis software, which provides capability to solve the contact problem, is used. It is found, however, that the computing time is extraordinarily long due possibly to the generality of the software and also to the ignorance of the control parameters used in the software. In this paper, the contact condition is imposed directly by the authors, while the software is used only to solve the ordinary displacement analysis problem. In this way, the computing time is decreased remarkably by more than 30 times, while yielding the same accurate results. Optimization is conducted based on this efficient analysis method to find minimum number of supporting bars using the response surface algorithm.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.385-386
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• 2002

The friction characteristics of contact region between vane tip and cam-ring is studied with an experimental device model. The radius of vane tip is less than 1 mm and sliding speed is lower than 10 m/s. The friction characteristics of the actual oil hydraulic vane pump is estimated on the basis of coefficient of friction. The coefficient of friction can be obtained by measuring the frictional forces in the contact region. The lubrication condition between vane and disk is modeled after the actual condition between the vane and cam-ring.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.115-118
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• 2007

The geometry of wheel and rail profiles is the primary contributor to wheel and rail interaction. These profiles interact to influence truck steering, vehicle lateral stability, wheel/rail wear and surface damage. Maintaining good control of the profiles is one of the keys to ensuring preferred wheel and rail interaction. Transportation Technology Center, Inc., Pueblo, Colorado, is developing an automated measurement system for wheel/rail contact condition inspections supported by AAR(Association of American Railroads). The system uses a modified version of $WRTOL^{TM}$ (Wheel/Rail Tolerances)--software that performs extensive analysis of wheel and rail contact conditions

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.10a
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• pp.102-108
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• 1995

Internal contact scheme between two free surfaces on one deforming body has been proposed by using the penalty method. It has been imposed to be internal boundary condition on two-dimensional thermo-viscoplastic finite element method so as to analyze one deforming body, which has two free surfaces penetrating each others. Analysis of side pressing with a circular void and a inclined elliptic hole have been carried out in order to verity the proposed contact scheme. A finite element code imposed internal boundary condition has been applied to two-dimensional analysis of free forging of large ingot with a void. Through the analysis, effects of working parameters in order to consolidate voids have been investigated.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.730-735
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• 2005

In this thesis, As electric railway vehicle's speed becomes faster and faster and functional, the conditions of operation (or running condition) of the vehicle also become complicated and diverse. As the number of electric vehicle increases by enhancement of the running condition, problems are also raised in circulation current, vibration and unstable contact caused by equipment(sporting part for making horizontal between Trolley wire and Messenger wire) and troubles in Ark by un secure contact. This articles shows a method to prevent or to have least problem of vibration, and unstable contact by having constant height of Trolley wire through adjusting the length of Hanger.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.3
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• pp.35-40
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• 2004

Since the scale of vessels is growing up recently, some troubles between the shaft and after bush bearing are frequently reported. Generally, mean pressure on bush bearing is used as a design criterion. However, in some case of the long bearing such as after bush bearing of the propulsion shaft, it might be liable to be locally under high pressure. As for the main engine bearings and the intermediate shaft bearing, it is reasonable to take the mean pressure as a design criterion. But, in case of after bush bearing, it is not sufficient because of the possibility of high pressure caused by local contact. In this study, Hertzian contact condition was applied to evaluation of the local pressure for after bush bearing. To reduce the local maximum pressure, the height of the after bush bearing was controlled. It was found that local maximum pressure could be reduced effectively by taking a partial slope on the white metal of the aft bush bearing.

• Korean Journal of Acupuncture
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• v.26 no.2
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• pp.1-13
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• 2009

Objective: Optical Coherence Tomography (OCT) has emerged as an important optical imaging modality in non-invasive medical diagnostics. Hence, the aim of this study is to measure the similarity of the diagnosis by a traditional method using doctor's hand for feeling of pulse and by the non-contact/non-invasive pulse analyzing system using OCT on Chon(寸), Kwan(關), Chuk(尺). Method: Four korean medical doctors and the non-contact/non-invasive pulse analyzing system using OCT have measured the rapidity, the dimension, and the power of pulse waves of 25 volunteers. First, four korean medical doctors measured pulse waves of volunteers. During measuring, four doctors were separated from each other and so were volunteers. And then, the pulse waves of volunteers were measured by OCT. This was performed on the right Chon(寸), Kwan(關), Chuk(尺). Results: The study showed that the traditional method and the OCT based method had the 88% matches on the values of the slow and rapid pulse condition (遲數), 64% matches on the values of the small and big pulse condition(微細弱緩大[洪]), and 72% matches on the values of the weak and strong pulse condition(虛實). Conclusions: Based on the high similarities of the measurements of two approaches, we suggest that the OCT based pulse diagnosis method is useful for compensating the traditional method for the pulse diagnosis.