• Title/Summary/Keyword: Contact condition

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Selective Contact Hole Filling by Electroless Ni Plating (무전해Ni도금에 의한 선택적 CONTACT HOLE 충진)

  • 김영기;우찬희;박종완;이원해
    • 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.

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Propagation Behavior of Inclined Surface Crack of Semi-Infinite Elastic Body under Hertzian Contact (반무한 탄성체의 헤르츠 접촉하의 경사진 표면균열의 전파거동)

  • 김재호;김석삼;박중한
    • 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.

On the Slipping Phenomenon in Adhesive Complete Contact Problem (응착 완전 접촉 문제에서 접촉면 미끄럼 현상에 관한 고찰)

  • Kim, Hyung-Kyu
    • 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, σrq and σq, respectively, are evaluated via asymptotic analysis. The ratio of σrqqq 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 |σθθ| ≥ |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.

A study on contact analysis and optimum support design using commercial analysis software (상용 해석 소프트웨어를 이용한 접촉문제의 효과적 해석 및 최적 지지점 설계)

  • Won June-Ho;Choi Joo-Ho
    • 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.

An Experimental Study on the Friction Characteristics of Oil Hydraulic Vane Pump

  • Cho, Ihn-Sung;Dong, Myeong-Seon;Jung, Jae-Youn
    • 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.

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AAR's R&D Status on An Automated Measurement System for Wheel/Rail Contact Condition Inspection (미국철도협회의 차륜/레일 접촉상태 차상 자동검측 기술 개발 현황)

  • Chung, Heung-Chai
    • 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

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Two-Dimensional Thermo-Viscopiastic Finite Element Analysis of Free Forginf for Large Ingot Considerinf Internal Contact Treament on One Deforming Body (변형하는 동일물체간의 접촉처리를 고려한 대형강괴 자유단조의 2차원 열점소성 유한요소해석)

  • 박치용;양동열
    • 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.

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A Suggestion for Improvement of Hanger length adjusting method in Trolley Wire Line (전차선로 행거의 길이조절방식 개선방안)

  • Kim Gyun-Sig;Park Han-Cheol;Park Han-Yong;Cha Kwang-Seok
    • 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.

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Pressure Distribution Analysis for After Bush Bearing of Ship Propulsion Shaft (선박 추진축 선미 베어링 압력 분포 해석)

  • 신상훈;최익흥
    • 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.

The study of non-contact/non-invasive pulse analyzing system using Optical Coherence Tomography (OCT) for oriental pulse diagnosis (비접촉식 광생체단층촬영 기술을 이용한 맥진 연구 -맥의 빠르기, 크기 및 맥력을 중심으로-)

  • Na, Chang-Su;Youn, Dae-Hwan;Kim, Young-Sun;Lee, Chang-Ho;Jung, Woon-Sang;Kim, Jee-Hyun;Choi, Chan-Hun
    • 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.

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