• Fibers and Polymers
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• 제7권3호
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• pp.310-316
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• 2006

In this article, an attempt has been made to explain the failure mechanism of spun yams. The mechanism includes the aspects of generation and distribution of forces on a fibre under the tensile loading of a yam, the free body diagram of forces, the conditions for gripping and slipping of a fibre, and the initiation, propagation, and ultimate yam rupture in its weakest link. A simple mathematical model for the tenacity of spun yams has been proposed. The model is based on the translation of fibre bundle tenacity into the yam tenacity.

• 한국안전학회지
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• 제8권4호
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• pp.139-148
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• 1993

Thermosyphons are simple devices that can passively transport thermal energy over relatively long distance with little temperature degradation. These attributes permit the use of low grade thermal energy for thermal control of structures including the snow melting and deicing to the pavement surface. The thermosyphon system requires no costly energy input and Is completely maintenance free. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to transfer the geothermal energy to the pavement to obviate slipping traffic accidents due to freezing of pavement in winter.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.475-478
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• 2004

In this paper, a magnet-type automatic pipe cutting machine that binds itself to the surface of the pipe using magnetic force and executes unmanned cutting process is proposed. During pipe cutting process when the machine moves around the pipe laid vertical to the gravitational field, the gravity acting on the pipe cutting machine widely varies as the position of the machine varies. That is, with same driving force from the driving motor the cutting machine moves faster when it climbs down the surface of the pipe and moves slower when it climbs up to the top of the pipe. To maintain a constant velocity of the pipe cutting machine and improve the cutting quality, the authors adopted a conventional PID controller with a feedforward effort designed based on the encoder measurement of the driving motor. It is, however, impossible for the encoder at the motor to measure the absolute position and consequently the absolute velocity of the cutting machine in the case where the slip between the surface of the pipe and wheel of the cutting machine is not negligible. As an attempt to obtain a better estimation of the absolution angular position/velocity of the machine the authors proposes the use of the MEMS-type accelerometer which can measure static acceleration as well as dynamic acceleration. The estimated angular velocity of the cutting machine using the MEMS-type accelerometer measurement is experimentally obtained and it indicates the significant slipping of the machine during the cutting process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.131-136
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• 2004

The limited slip differential(LSD) is a device which enables the driving force to be transmitted from one slipping wheel to another wheel in such case that the car is stuck in clay or snow. When the unwanted slipping occurs on one wheel, the LSD temporarily restraints the differential motion to transmit the driving force in the other wheel. So far, many types of LSD were developed such as mechanical lock type, disk clutch type, viscous coupling type, torsion type and multiple clutch type. However these types of LSD is too complicated and expensive, so it is used only for 4WD outdoor vehicles, military vehicles, and a portion of deluxe car. So, many studies has been devoted to improve new types of LSD to cover those demerits of existing LSDs that the hydraulic LSD is developed as arepresentative result of that. The hydraulic LSD which uses the principle of gear pump is packed with viscous oil in tight container. When a slip occurs on one wheel, the hydraulic LSD generates torque caused by high oil pressure in the container. This study has been devoted to suggest an improved hydraulic LSD. In order to achieve it, we designed a new type of hydraulic LSD, produced it and did a rig test with it on real vehicle. From the rig test, it has been confirmed that the new type of hydraulic LSD can be directly applied to exiting vehicles without changing the design criteria

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2013년 춘계학술대회
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• pp.19-29
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• 2013

Slips and falls are associated with many occupational injuries in Korea. It is also estimated that slipping are major contributors to slip, trip and fall injury burden. So "LOCAL RULE ON OCCUPATIONAL SAFETY AND HEALTH STANDAR D" must be improved, especially article 3(prevention of slip, trip and fall). 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 another regulation 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. The article 3 was revised as below. 1. The floors of the traffic route in workplace shall have no hole or slope, or be uneven or slippery so as, in each case, to expose employees to slip, trip and fall risk, except if adequate measures have been taken to prevent a employees falling. 2. The employer shall design, install and fix the drain for effective drainage if fluid contaminants were frequently occurred. So far as is reasonably practicable, An employer shall keep the workplace clean, sanitary, and dry so that employees won't have any risk to tripping or slipping at the workplace. 3. To facilitate cleaning, every floor, workplace, and passageway shall be, so far as is reasonably practicable, kept free from protruding objects, splinters, holes, etc. Also, some criteria was developed in this study. Standard and criteria developed in this study will help to prevent slip, trip, and fall injuries.

• 한국인터넷방송통신학회논문지
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• 제20권5호
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• pp.79-88
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• 2020

본 연구에서는 태양광 패널 청소 로봇이 진공 패드 압력을 이용하여 경사진 패널 위를 미끄러짐 없이 효율적으로 주행하는 방법을 제안한다. 이 방법에서는 로봇을 경사로 패널에 고정시키기 위해 로봇 발에 부착된 고무 패드의 압력을 진공으로 만들게 된다. 구동 방식으로 Linkage 매커니즘을 적용하여 미끄러짐을 방지함과 동시에 중량을 감소하여 소모전력을 낮추는 방법을 제안하였다. 로봇의 안전한 구동을 위하여 솔레노이드 밸브, 근접 센서, 엔코더를 사용하여 로봇의 움직임을 감지하며, 주행할 때 고무 패드의 압력을 제어하여 안전한 경사로 주행을 가능하게 하였다. 로봇의 전진 동작을 위하여 다중의 솔레노이드 밸브들의 동작 시퀀스를 완성하여 양쪽 발에 부착된 6개의 진공패드가 진공 및 대기압을 정확하게 형성 할수 있도록 제어하여 이동 중 미끄러짐 없이 전진할 수 있게 하였다. 마지막으로 주행 및 회전 실험을 통해 36도의 태양광 패널에서 직진 및 회전 동작을 수행할 수 있음을 확인하였다.

• Journal of Korean Neurosurgical Society
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• 제30권sup1호
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• pp.61-67
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• 2001

Objectives : To demonstrate the preventive effect on post-operative spinal deformity of the laminoplasty compared with laminectomy for spinal cord tumor. Methods : Sixteen patients who underwent laminoplasty and 89 patients who underwent lamenectomy were reviewed retrospectively after removal of spinal cord tumors between February 1981 and December 1999. The mean follow-up period after laminoplasty and laminectomy were 29 months(range, 12-49 months) and 66 months(range, 6-120 months) respectively. Patients were observed neurologically and radiologically. Results : Postoperative kyphosis was observed 17 patients(19%) in the laminectomy group, but was not observed in the laminoplasty group. Postoperative slipping was observed 16 patients(18%) in the laminectomy group, but was not observed in the laminoplasty group. Complications such as postoperative scoliosis, rotation, and swan-neck deformity were observed in the laminectomy group, but were not observed in the laminoplasty group. Conclusions : Laminoplasty prevented postoperative spinal deformities after removal of spinal cord tumors, and afforded anatomic reconstruction of the vertebral arch. Additionally, appropriate patient selection maximizes the chance of optimal neurologic outcomes and minimizes complications. Laminoplasty appears to warrant further evaluation as an alternative to wide laminectomies for exposure of intraspinal tumors.

• Geomechanics and Engineering
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• 제28권4호
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• pp.335-346
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• 2022

Buckling failure is a typical slope instability mode that should be paid more attention to. It is difficult to provide systematic guidance for the monitoring and management of such slopes due to unclear mechanism. Here we examine buckling failure as the potential instability mode for a slope above a railway tunnel in southwest China. A comprehensive model test system was developed that can be used to conduct buckling failure experiments. The displacement, stress, and strain of the slope were monitored to document the evolution of buckling failure during the experiment. Monitoring data reveal the deformation and stress characteristics of the slope with different slipping mass thicknesses and under different top loads. The test results show that the slipping mass is the main subject of the top load and is the key object of monitoring. Displacement and stress precede buckling failure, so maybe useful predictors of impending failure. However, the response of the stress variation is earlier than displacement variation during the failure process. It is also necessary to monitor the bedrock near the slip face because its stress evolution plays an important role in the early prediction of instability. The position near the slope foot is most prone to buckling failure, so it should be closely monitored.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.38-46
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• 1999

Numerical methods are procured for evaluating the contact stresses, the dissipation of friction energy density and the fatigue cracking emanated from the contact surface under the partial slip condition. A rounded punch is used for the indenter pressing and slipping on the elastic half plane. Plane strain condition is assumed for the present analysis. Several sample calculations are carried out to investigate the effect of the punch roundness, the shear load path, and the crack obliquity and closure on the failure. It is found that the present methods can be a useful tool for studying the physical failure of the of the contacting materials such as fretting wear and fretting fatigue cracking.

• 대한인간공학회지
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• 제10권2호
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• pp.51-55
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• 1991

Since slipping has been identified as a major hazard, it is important to understand the mechanism of a slip. Many researches, based on biomechanical studies, had been attempted to do that. Thowever, the correlation between the mechanism of a slip and psychophysical behaviors of people had rarely been verified. For example, the existence of small slips in a forward direction, which do not normally perceived by human subjects, has been established by several experimenters. However, the term "microslips are not perceived by the walkers[4]." has not been examined precisely by any experiments. The objective of this study is, using a Signal Detection Theory (SDT), to define a microslip and slip more quqntitatively with the biomechanical measurement of slip distance. The results showed that, the slip distance around the 3 centimeters, there was a obvious change in the accident detectability of the subject. The conclusion is that it is possible to identify the boundary of a microslip and slip around the 3 centermeters of slip distance.