• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.53-59
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• 2009

The purpose of this study was to clarify the clinical efficiency of tungsten carbide/carbon coating on obtaining optimal preload of abutment screw compared with non-coated screw in external-hex implant system. In the present work, rotational value and the compressive force between abutment and fixture of abutment screws without coating and with coating tightened to 30Ncm were measured. Mean compressive force of coated screw was 504.6N. Then uncoated screw was tightened to clamping the abutment and the implant to 504.6N, and the tightening torque value and the rotational value was recorded. The following conclusions were drawn within the limitation of this study. Compressive force of coated screw was higher than that of uncoated screw after tightening at 30Ncm. The tightening torque that was nedeed to clamping the uncoated screw equal to coated screw tightened to 30Ncm was 55.6Ncm. In case of equal compressive force, there was no significant difference in rotation value between coated and uncoated screw.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.8
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• pp.849-855
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• 2008

An experimental method based on contact resonance is developed to extract the contact parameters of mechanical joints under various clamped conditions. Mechanical joint parameters of shear contact stiffness and damping were extracted for different physical joint parameters such as surface finish of the mating surfaces, the presence of lubrication, the effect of the clamping pressure, and shear load. It was found that the shear contact stiffness values decreased with increasing clamping load and increased with increasing shear loading. Contact damping ratio values were almost constant with clamping load, but decreased with increasing shear load. Moreover, rough surfaces exhibited the highest shear stiffness and contact damping compared to smooth surfaces.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.259-268
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• 2000

In the friction-type joints the external applied load is transmitted by frictional force acting on the contact area of the plates fastened by the high strength bolts. This frictional force is proportional to the product of the bolt clamping force and slip coefficient of the faying surface. But the bolt clamping force is dependent on many factors when the turn-of-nut method is used. The preserved thread length and length-to-diameter ratios are one of the major factors governing the bolt clamping force. This paper presents the correct method of high strength bolt tightening through the experiment on the mechanical properties on sets of high strength bolts in accordance with preserved thread length and length-to-diameter ratios.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.173.2-173.2
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• 2005

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.951-952
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• 2011

발전소에 설치된 대용량 발전기는 고정자 권선을 지지하기 위해 축 방향으로 삽입된 슬롯 Wedge의 지지압력이 느슨해지면 절연파괴와 같은 각종 사고가 발생할 수 있다. 이를 예방하기 위해 주기적으로 Wedge 조임 상태를 점검하고 있으나 그동안 작업자의 손가락 감각으로 평가하던 방법을 가속도 진동 센서를 이용하여 주파수 스펙트럼을 분석함으로써 발전기 고정자 Wedge 조임 상태를 객관적으로 판정할 수 있도록 방법을 고안하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7166-7175
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• 2015

This paper is a study on using gas springs for reduced friction in the elevation of the large television stand. Target is applied to the operation of the elevation over 50-inch television that uses a gas spring. Gas seal lip technology is needed for development acting on the piston rod in order to obtain a reduction in friction in elevation operation. In order to acting on the gas seal lip technology, the improved friction force can be obtained through the inner diameter of gas seal lip, the design of cutting angle and the changes of material.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.95-101
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• 2000

The purpose of this study is to develop an improved measuring system, which allows for effectively measure spring clamping forces. This system consists of eight or twelve measuring points in order to acquire the clamping force distribution of the whole range of spring clamp. Each measuring point consists of load cells equipped with 4 strain gauges. Using different bearings, we calibrate the roundness of the measuring points. For quality control and database construction, a software system is established. furthermore, uncertainty is calculated to validate the confidence of this system. Various experiments confirm the effectiveness of this measuring system.

• 대한치과보철학회:학술대회논문집
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• 1996.11a
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• pp.95-95
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• 1996

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.131-138
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• 2006

Structural bracing concept equipped with a new and efficient friction based energy dissipation device is referred to Friction SliP Brace (FSB) where the behavior of the brace components is elastic until the axial resistant force in the brace exceeds the friction force developed at the frictional interface of the device. In this study, the FSB concept is modified and new type of hybrid energy dissipation device, the Active Friction SliP Braces (AFSB), is described. The FSB is by far improved in the AFSB by inclusion of an active clamping mechanism on the friction interface. The clamping action regulated by the developed algorithm is altered during the response of the building. The results indicate that the action of dissipating vibrational energy in the AFSB impacts on the response at later cycles by keeping the drift amplitudes at much lower levels, revealing overshooting problem due to its early slippage. Providing predetermined constant incremental strengths to the building by AFSB medium improves response by reducing drift amplitudes and base shear under small and medium amplitude ground accelerations.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.636-641
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• 2007

This research focuses on the development of an analytical model loosening mechanism of dental implant system. The model is utilized for predictions of preload values for internal and external types of implants. It identifies the effects of various parameters such as friction, geometric factors and mechanical properties on the loosening mechanism of the implant system. The results of analytical model are compared to those of the numerical method for validation.