• Journal of Korean Neurosurgical Society
• /
• v.37 no.4
• /
• pp.313-315
• /
• 2005

A 66 year-old woman was admitted to our hospital for progressive weakness of both lower extremities since a month ago. Imaging study, based on plain X-ray, computed tomography and magnetic resonance image revealed spinal stenosis owing to anterior slipping of T10/11 segment. Degenerative spondylolisthesis is common in the lumbar spine and rarely occurs in the cervical spine. But there was no report of degenerative spondylolisthesis in thoracic spine. The authors experienced a case of degenerative spondylolisthesis in the thoracic spine. And we achieved a satisfactory result with posterior decompressive laminectomy alone.

• Transactions on Control, Automation and Systems Engineering
• /
• v.3 no.2
• /
• pp.111-116
• /
• 2001

A neural network compensator for stick-slip friction phenomena in meashartonics servo systems is practically proposed to supplement the traditionally available position and velocity control loops for precise motion control. The neural network compensa-tor plays the role of canceling the effect of nonlinear slipping friction force. It works robustly and effectively in a real control system. This enables the mechatronics servo systems to provide more precise control in the digital computer. It was confirmed that the con-trol accuracy is improved near zero velocity and points of changing the moving direction through numerical simulation. However, asymptotic property on the steady state error of the normal operation points is guaranteed by the integral term of traditional velocity loop controller.

• Steel and Composite Structures
• /
• v.2 no.5
• /
• pp.315-330
• /
• 2002

This paper proposes a model for analysing the non-linear behaviour of steel concrete composite beams prestressed by external slipping cables, taking into account the deformability of the interface shear connection. By assuming a suitable admissible displacement field for the composite beam, the balance condition is obtained by the virtual work principle. The solution is numerically achieved by approximating the unknown displacement functions as series of shape functions according to the Ritz method. The model is applied to real cases by showing the consequences of different connection levels between the concrete slab and the steel beam. Particular attention is focused on the limited ductility of the shear connection that may be the cause of premature failure of the composite girder.

• Structural Engineering and Mechanics
• /
• v.4 no.3
• /
• pp.313-329
• /
• 1996

A mathematical model of a cable as a system of interacting wires with interwire friction taken into account is presented in this paper. The effect of friction forces and the interwire slip on the mechanical properties of tension cables is investigated. It is shown that the slip occurs due to the twisting and bending deformations of wires, and it occurs in the form of micro-slips at the contact patches and macro-slips along the cable. The latter slipping starts near the terminals and propagates towards the middle of the cable with the increase of tension, and its propagation is proportional to the load. As the result of dry friction, the load-elongation characteristics of the cable become quadratic. The energy losses during the extension are shown to be proportional to the cube of the load and in inverse proportion to the friction force, a result qualitatively similar to that for lap joints. Presented examples show that the model is in qualitative agreement with the known experimental data.

• Journal of Mechanical Science and Technology
• /
• v.14 no.2
• /
• pp.131-140
• /
• 2000

For a walking robot with high constant body speed, the dynamic effects of the legs on the transfer phase are dominant compared with other factors. This paper presents a new force distribution algorithm to maximize walkable terrain without slipping considering the dynamic effects of the legs on the transfer phase. Maximizing the walkable terrain means having the capability of walking on more slippery ground under the same constraint, namely constant body speed. A simple force distribution algorithm applied to the proposed walking model with a pantograph leg shows an improvement in the capability of preventing foot-slippage compared with one using a pseudo-inverse method.

• Proceedings of the IEEK Conference
• /
• 1999.11a
• /
• pp.629-632
• /
• 1999

In this paper, color coordinate system transformation based visual servo controller has been considered. Mobile robot always has a position error and an orientation error resulted from wheel slipping etc.. Even more, the errors have accumulative properties. So feedback from environments is important. In this paper, by using color model faster land mark extraction can be achieved. And the global position and the orientation of mobile robot can be known by only two land marks positions in image coordinate system. Finally, the adoption of visual information in path tracking problem makes visual servo control.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.3
• /
• pp.317-326
• /
• 2014

Slips and falls are associated with many public injuries in Korea. It is also estimated that slipping are major contributors to slip, trip and fall injury burden. The primary purpose of the present study is to determine if, and to what extent, the standard could be improved in present environment. In order to fulfill our objective, the regulations in Korea and foreign countries were investigated and reviewed. Many kind of standard, mandatory documents and guideline were also reviewed. And then, regulations, standard, guideline etc. reviewed were compared with each others. Also, some criteria was developed in this study. Standard and criteria developed in this study will help to prevent slip, trip, and fall injuries.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2005.03a
• /
• pp.55-61
• /
• 2005

The seismic response tests of a spent fuel dry storage cask model of 1/8 scale are performed for an typical 1940 Elcentro earthquake. This paper focuses on the seismic response test data generation to check the overturing possibility of a storage cask and the slipping displacement on concrete slab bed. A simplified cask model is used to take into account the variations in seismic load magnitude and cask/bed interface friction. The test results show that the model gives an overturning response for an extreme condition.

• Journal of the Ergonomics Society of Korea
• /
• v.10 no.1
• /
• pp.23-28
• /
• 1991

A major inhibition of past work in a slip/fall accident study has been due to the lack of a facility and a methodology to experimentally investigate such behavior without expowting human subjects to the natural danger of injury resulting from a fall. In order to carry out a slip/fall research, a unique facility must be created specially to investigate falling and slipping behavior. One component of this facility will be used to focus a research towards experimental investigations of the basic mechanisms involved in falls. Especially, this compo- nent must be designed, developed, and fabricated to provide passive, reactive support at the point of loss of ba- lance. This component must allow both normal and reduced friction surfaces to be designated to investigate human falling in the experimental conditions. This study will address how a fall arresting system was designed and it would be implemented in actual case of a slip/fall study.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.08a
• /
• pp.252-261
• /
• 1999

The troubles such as slipping, pinching and other behaviors in the service of cold rolling mills often induce thermal shock crack on the surface of work roll, and considerably reduce their service lives. In order to evaluate thermal shock resistibility we use thermal shock tester generating frictional heat caused by a rotating disc contacting with test specimens. Thermal shock produces two heat affected layers below the roll surface, one is rehardened layer and the other is succeeding tempered layer. The maximum depth of crack occurred in a thermal shocked area is a criterion for the thermal shock resistibility. This paper describes on the investigation to the influence of hardness and residual stress.