• Title, Summary, Keyword: Slip

Search Result 2,998, Processing Time 0.218 seconds

Backward Slip as a Measure of Floor Slipperiness (미끄럼 측정치로서의 뒤로미끄러짐)

  • Myung, Rohae
    • Journal of the Ergonomics Society of Korea
    • /
    • v.20 no.2
    • /
    • pp.47-57
    • /
    • 2001
  • To simulate an actual slip to measure floor slipperiness, slip resistance testers simulate slip in only forward direction because forward slip in the landing phase was found to be the most important factor for loss of balance. Backward slip in the take off phase was possible but was excluded in the friction test protocol because it was not dangerous. However, backward slip was tested in the friction test protocol without any theoretical background of the significance in generating dangerous slips and falls and was proven to be as good as forward slip in measuring floor slipperiness. Therefore, this study was designed to investigate the significance of backward slip in generating dangerous slips and falls with different combinations of floor and shoe sole. The results showed different tendency of backward slip in take off phase being significant in generating dangerous slips and falls because backward slip in the takeoff phase affected gait pattern disturbances seriously. resulted in dangerous falls. Fast toe velocity increased the severity of backward slip and confirmed the significance of backward slip in generating dangerous slips and falls. As a result, this study recommends the utilization of backward slip in the measurement of floor slipperiness.

  • PDF

Influence of Stick-Slip Behavior on the Friction Force under Fretting Conditions (프레팅 조건 하에서 스틱-슬립 현상이 마찰력에 미치는 영향)

  • Lee Young-Ze;Jeong Sung-Hoon;Yong Suk-Ju
    • Tribology and Lubricants
    • /
    • v.21 no.1
    • /
    • pp.16-20
    • /
    • 2005
  • Friction and wear characteristics between two steel surfaces under fretting condition are investigated experimentally. The fretting damage caused by low-amplitude oscillatory sliding can be classified into three regimes of gross-slip, mixed-slip and partial-slip due to stick-slip phenomenon. One of the most important characteristics of fretting wear is the transition from gross-slip to mixed-slip. This study was focused on getting the degree of stick-slip out of the friction transition under fretting condition. Fretting wear is divided into three conditions of gross-slip/mixed-slip/partial-slip. The criteria for the division are friction and displacement amplitude, wear scar morphology and dissipated energy. In this test, friction force and displacement were measured for detecting the transition from mixed-slip to gross-slip and qualitatively predicting the degree of the wear.

Effects of viscosities of slip on slip casting and properties of sintered bodies of cordierite (Slip의 점도가 slip casting 및 casting 및 cordierite 소결체의 특성에 미치는 영향)

  • Baik Yong-Hyuck;Chang Pok-Kie;Kwak Hyo-Sup
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.15 no.5
    • /
    • pp.202-207
    • /
    • 2005
  • We have investigated the relationship between a viscosity of the slip prepared from kaolin, quartz, $Mg(OH)_2$, etc and its influence on the speed of slip casting and the microsturcture of a sintered body. The speed of slip casting decreases as a viscosity of a slip decreases. The optimized viscosity range of a slip was found to be around $3.0\~17.0\;cP$. By careful controlling a viscosity of slip, homogeneous microstructure of outer surface layers, inner surface layers, intermediate layers, and inside layers were obtained by casting process. The specimen sintered at $1350^{\circ}C$ consists of a cordierite crystalline phase only as a constituent mineral.

Design and Analysis of a Dual Round-Robin based iSLIP (DiSLIP) Scheduling Scheme for IP Switching System (IP 스위칭 시스템을 위한 iSLIP 스케줄링에 기반의 Dual 라운드로빈 설계 및 분석)

  • Choi, Jin-Seek;Yang, Mi-Jung;Kim, Tae-Il
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.44 no.3
    • /
    • pp.41-50
    • /
    • 2007
  • In this paper, a new Dual Round-Robin (DRR) based iterative SLIP (iSLIP) scheduling scheme, called DiSLIP is proposed for IP switching systems. By using DRR followed by iSLIP, DiSLIP can exploit desynchronization effect of DRR and high performance of iSLIP, while the drawbacks of two schemes are minimized. 'Through computer simulation, we verify the switch throughput and total waiting time of the proposed scheme under nonuniform and correlated self-similar traffic. Moreover, the proposed scheme can considerably reduce the complexity of parallel matching logics compared to iSLIP. From the result, we observe that the proposed scheme outperforms DRR on throughput as well as iSLIP schemes on complextiy.

Numerical Analysis of the Slip Velocity and Temperature-Jump in Microchannel Using Langmuir Slip Boundary Condition (미소채널내의 Langmuir 미끄럼 경계조건을 통한 미끄럼 속도 및 급격한 온도변화에 관한 수치해석)

  • Kim, Sang-Woo;Kim, Hyun-Goo;Lee, Do-Hyung
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.33 no.3
    • /
    • pp.164-169
    • /
    • 2009
  • The slip velocity and the temperature jumps for low-speed flow in microchannels are investigated using Langmuir slip boundary condition. This slip boundary condition is suggested to simulate micro flow. The current study analyzes Langmuir slip boundary condition theoretically and it analyzed numerically micro-Couette flow, micro-Poiseuille flow and grooved microchannel flow. First, to prove validity for Langmuir slip condition, an analytical solution for micro-Couette flow is derived from Navier-Stokes equations with Langmuir slip conditions and is compared with DSMC and an analytical solution with Maxwell slip boundary condition. Second, the numerical analysis is performed for micro-Poiseuille flow and grooved microchannel flow. The slip velocity and temperature distribution are compared with results of DSMC or Maxwell slip condition and those are shown in good agreement.

TECHNIQUE OF SEPARATE MEASURING SIDE SLIP FOR TOE ANGLE AND CAMBER ANGLE

  • Nozaki, H.
    • International Journal of Automotive Technology
    • /
    • v.7 no.6
    • /
    • pp.681-686
    • /
    • 2006
  • The current flat type side slip tester measures only the total side slip. Therefore, measurement techniques which can be used to determine the side slip for each alignment element were examined. Because the side slip related to the camber angle varies depending on the unit load per travel wheel while the side slip related to the toe angle does not on the unit per travel wheel, but depends only on the direction of the tire, the side slip for each alignment element can be determined separately.

Maximum Braking Force Control Using Wheel Slip Controller and Optimal Target Slip Assignment Algorithm in Vehicles (휠 슬립 제어기 및 최적 슬립 결정 알고리즘을 이용한 차량의 최대 제동력 제어)

  • Hong Dae-Gun;Hwang In-Yong;SunWoo Myoung-Ho;Huh Kun-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.30 no.3
    • /
    • pp.295-301
    • /
    • 2006
  • The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional ABS systems. In order to achieve the superior braking performance through the wheel-slip control, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance, stability enhancement, etc. In this paper, a robust wheel slip controller is developed based on the adaptive sliding mode control method and an optimal target slip assignment algorithm. An adaptive law is formulated to estimate the longitudinal braking force in real-time. The wheel slip controller is designed using the Lyapunov stability theory and considering the error bounds in estimating the braking force and the brake disk-pad friction coefficient. The target slip assignment algorithm is developed for the maximum braking force and searches the optimal target slip value based on the estimated braking force. The performance of the proposed wheel-slip control system is verified In simulations and demonstrates the effectiveness of the wheel slip control in various road conditions.

Bond Stress-Slip Model of Reinforced Concrete Member under Repeated Loading (반복하중을 받는 철근콘크리트 부재의 부착응력-슬립 모델)

  • Oh, Byung-Hwan;Kim, Se-Hoon;Kim, Ji-Sang
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.104-107
    • /
    • 2004
  • The crack widths of reinforced concrete flexural members are influenced by repetitive fatigue loadings. The bond stress-slip relation is necessary to estimate these crack widths realistically. The purpose of the present study is, therefore, to propose a realistic model for bond stress-slip relation under repeated loading. To this end, several series of tests were conducted to explore the bond-slip behavior under repeated loadings. Three different bond stress levels with various number of load cycles were considered in the tests. The present tests indicate that the bond strength and the slip at peak bond stress are not influenced much by repeated loading if bond failure does not occur. However, the values of loaded slip and residual slip increase with the increase of load cycles. The bond stress after repeated loading approaches the ultimate bond stress under monotonic loading and the increase of bond stress after repeated loading becomes sharper as the number of repeated loads increases. The bond stress-slip relation after repeated loading was derived as a function of residual slip, bond stress level, and the number of load cycles. The models for slip and residual slip were also derived from the present test data. The number of cycles to bond slip failure was derived on the basis of safe fatigue criterion, i.e. maximum slip criterion at ultimate bond stress.

  • PDF

Predictions of Microscale Separated Flow using Langmuir Slip Boundary Condition (Langmuir 미끄럼 경계조건을 이용한 미소 박리유동의 예측)

  • Lee, Do-Hyung;Meang, Joo-Sung;Choi, Hyung-Il;Na, Wook-Sang
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.27 no.8
    • /
    • pp.1097-1104
    • /
    • 2003
  • The current study analyzes Langmuir slip boundary condition theoretically and it is tested in practical numerical analysis for separation-associated flow. Slip phenomenon at the channel wall is properly implemented by various numerical slip boundary conditions including Langmuir slip model. Compressible backward-facing step flow is compared to other analysis results with the purpose of diatomic gas Langmuir slip model validation. The numerical solutions of pressure and velocity distributions where separation occurs are in good agreement with other numerical results. Numerical analysis is conducted for Reynolds number from 10 to 60 for a prediction of separation at T-shaped micro manifold. Reattachment length of flows shows nonlinear distribution at the wall of side branch. The Langmuir slip model predicts fairly the physics in terms of slip effect and separation.

Fretting Wear Mechanisms of Zircaloy-4 and Inconel 600 Contact in Air

  • Kim, Tae-Hyung;Kim, Seock-Sam
    • Journal of Mechanical Science and Technology
    • /
    • v.15 no.9
    • /
    • pp.1274-1280
    • /
    • 2001
  • The fretting wear behavior of the contact between Zircaloy-4 tube and Inconel 600, which are used as the fuel rod cladding and grid, respectively, in PWR nuclear power plants was investigated in air. In the study, number of cycles, slip amplitude and normal load were selected as the main factors of fretting wear. The results indicated that wear increased with load, slip amplitude and number of cycles but was affected mainly by the slip amplitude. SEM micrographs revealed the characteristics of fretting wear features on the surface of the specimens such as stick, partial slip and gross slip which depended on the slip amplitude. It was found that fretting wear was caused by the crack generation along the stick-slip boundaries due to the accumulation of plastic flow at small slip amplitudes and by abrasive wear in the entire contact area at high slip amplitudes.

  • PDF