• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.9-14
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• 2007

In this paper, a rotating tool clamping device was developed based on a shape memory alloy(SMA) and its feasibility as a tool holder was experimentally explored. The SMA-based device was able to alter clamping to unclamping through temperature control within 1 second. The means and repeatability(${\sigma}$) of the tool clamping force were 185.5N and 6N respectively and its drifts were less than 3% for an hour. Considering the temperature hysteresis of the SMA-based tool clamping device, it is necessary to heat the SMA ring to around $50^{\circ}C$ after tool change to obtain more clamping force.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.581-589
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• 2019

Guided missiles assembled with the bolted joint are subjected to various shock loading conditions while flying in the air and operating on the ground or platform. Especially, It is important to analyze the effect of the shock load on the structure because it affects the structure for a short duration time while its acceleration magnitude is quite large. In this study, mechanical shock tests on the structure with the bolted joint have been carried out to measure the acceleration changes of the structure against external shock loads by electrical exciter. Variation of dynamic characteristics of a structure with fastening methods and fastening forces has been investigated through Shock Response Spectrum analysis.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.326-328
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• 2006

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.155-163
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• 2001

A number of screws are inevitably used for tightening flanges in constructing a vacuum system. A theoretical relation between the axial force and the torque exerted on a screw is easily obtained assuming that the friction force generated on the contacting plane is known, however, in practice the friction is influenced strongly by unknown detailed surface condition. It is difficult to tighten optimally and uniformly the flange seals if the screws commercially available have undefined surface conditions and scattered dimensions, and the axial force produced by the screws can not be expected properly. In this paper a scatter of the axial force over screws and the deviation from an expected one, depending on various fastening conditions, are investigated using a variety of M8, the most popular size for vacuum flanges, domestic stainless screws of hexagonal head and standard thread.

• International Commerce and Information Review
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• v.13 no.3
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• pp.97-118
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• 2011

The Korea-Chile FTA talks began in December 1999 and concluded in October 2002, with official endorsement in April 2004. This FTA of a first for Korea, went into effect on April 1 in 2004. The purpose of this study to measure the Chile product evaluation in the Korean consumer after Korea-Chile FTA signed. The major result of article can be summarized as the follows: This paper investigates the determinants of 'product attitude', 'quality recognition', 'price recognition', 'use safety', 'use convenience', and 'design(appearance)'. There are 500 sended samples and 487 returns, 476 of them are analyzed for a entry competitiveness. In the analysis result of the article, The first, multiple regression result shows that the Chile goods evaluation are positively affected by the 'product attitude', 'price recognition', 'use safety', 'use convenience', and 'design(appearance)'. However, The 'quality recognition' factor do not affect in Chile goods evaluation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1129-1134
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• 2007

Payload fairing protects satellites and electrical equipments from the external environment. Payload fairing is jettisoned before satellite separation. Assembly frame for the separation of payload fairing were assembled with shear bolts. The role of shear bolts is to support structural load during flight and they are cut by explosion of pyro. The assembly frame which is connected by shear bolts is separated after the cutting of shear bolts. In this paper, structural tests and analysis were done for the design of the shear bolt. Compression, bending and shear load apply to the hardware including assembly frame. Test results showed that design of the shear bolt satisfied both structural strength for the support of flight load and required low strength for the cutting of shear bolts.

• Computational Structural Engineering
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• v.7 no.3
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• pp.133-141
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• 1994

When a bolt is tightened up to the range of plastic deformation, yielding may be governed by the combined stresses due to the axial force developed in the bolt and the frictional torque induced on the thread by the contact with the nut. Consideration is taken account of the fact that the unengaged portion of the thread has least sectional area, being subject to initial yielding. Once yielding has taken place some strain hardening effect may result. Incremental stress-strain relations are used to treat the continued yielding, which is equivalent to treat continued yielding as if summing up the effects of thin walled cylinders subject to plastic deformation. M10 bolts of fine threads are used for both computational and experimental purposes. Variation of axial forces and frictional torques vs. the frictional coefficients are presented together with other plots showing some characterist of bolt under plastic deformation. Finally, a design and control aid for the tightening(i.e., kind of nomograph) is presented, showing the relationships among the torque factor and frictional coefficients for that particular bolt used in the experiment.

• Journal of Korean Society of Forest Science
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• v.94 no.1 s.158
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• pp.50-57
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• 2005

This paper examines the relative competitive position of korean forest products market over period of 1999 to 2003 and selects strategic exported goods from its position provide against concluding FTA agreement with China, Japan and ASEAN. The portfolio approach is used to develope competitiveness-market share matrix. The position of major export countries on the competitiveness-market share matrix will be in one of nine cells, with differing implications for their role in korean forest products market. Based the competitiveness-market share matrix, Major export countries are divided into first cell type, third cell type and ninth cell type and the items of ninth cell type are chosen as strategic exportable goods.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.190-196
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• 2005

The power steering hose assembly is usually manufactured through the swaging process, which is conducted to connect a hose with metal fittings. In this process the hose is inserted into metal components, the sleeve and the nipple, and compressed in the radial direction by the jaws to clamp the hose with metal components. In case that the clamping force is small, the oil in the hose can leak locally under the severe operating conditions. To confirm the clamping force requirements, the measurement of separation force in longitudinal direction of the hose is usually performed. In this study, the swaging process of a hose is simulated with the finite element method, to investigate the effect of friction coefficient on the separation fDrce. The results interpretations are ffcused on the inner rubber component, and also a formula is proposed to estimate the separation farces with respect to friction coefficients.

• Journal of Korean Society of Steel Construction
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• v.26 no.3
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• pp.231-240
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• 2014

The T-stub subjected to an axial tensile force shows various behavior characteristics according to the changes in the diameter and tightening force of the fastener, the geometric shape of the T-stub, and the material properties of the T-stub and fastener. Due to the influence of these changes, the T-stub shows three failure modes: plastic failure after the flexural yielding of the T-stub flange, flexural yielding of the T-stub fillet, and fracture of the fastener. In general, a T-stub with a thin flange and where the gauge distance of the fastener is long has a larger energy dissipation capacity than a T-stub with a thick flange and where the gauge distance of the fastener is short, due to the plastic deformation after flexural yielding. In this study, three-dimensional nonlinear finite element analysis was carried out to determine the effect of the fastener used for fastening the T-stub on the energy dissipation capacity of the T-stub. For the fastener of the T-stub analysis model, F10T-M20 high-tension bolts and ${\varnothing}19.05-mm$ (3/4-inch) SMA bars were modeled, and the geometric shape of the T-stub was selected to represent the flexural yielding of the T-stub fillet and the axial tensile failure of the fastener.