• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.424-432
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• 1989

A mathematical model is developed for determination of the dynamic cutting force from static cutting data. The dynamic cutting force is analytically expressed by the static cutting coefficient and the dynamic cutting coefficient which can be determined from the cutting mechanics. The proposed model is verified by the chatter stability charts. A good agreement was shown between the stability limits predicted by the theory and the critical width of cut determined by experiments. The static cutting coefficient dominates high speed chatter stability, while the dynamic cutting coefficient dominates low speed chatter stability.

• Journal of Biomedical Engineering Research
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• v.17 no.2
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• pp.215-220
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• 1996

Impact force and strains induced by impact between the occluder and the struts have been measured with force sensor and strain gages. The maximum reaction force was about 25N, and the calculated impact force on the root of the struts amount about 9-17W. Impact force on the inlet strut is greater than that of the outlet strut, but the strain on the outlet strut is much higher than that of the inlet strut. These values might cause severe damage on the valve in the critical cases. The results of this study may be extended for the analysis of the endurance limit and optimal design of the struts and occluder.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.7-12
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• 2008

A far field solution of the slowly varying force on an offshore structure by gravity ocean waves was shown as a function of the reflection and transmission of the body disturbed waves. The solution was obtained from the conservation of the momentum flux, which simply describes various wave forces, while making it unnecessary to compute complicated integration over a control surface. The solution was based on the assumption that the frequency difference of the bichromatic incident waves is small and its second order term is negligible. The final solution is expressed in term of the reflection and transmission waves, i.e. their amplitudes and phase angles. Consequently, it shows that not only the amplitudes but also the phase differences make critical contributions to the slowly varying force. In a limiting case, the slowly varying force solution gives the one of the mean drift force, which is only dependent on the reflection wave amplitude. An approximation is also suggested in a case where only the mean drift force information is available.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.1
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• pp.11-16
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• 2016

Lithography techniques are generally used to manufacture nano-patterns on silicon, however, it is difficult to make a V-shaped pattern using these techniques. Although silicon is a brittle material, it can be treated as a ductile material if mechanically machined at extremely low force scale. The manufacturing technique of nano-patterns on single crystal silicon using a mechanical method was developed in this study. First, the linear pattern was machined on the silicon with increasing thrust force. Then, the correlation between measured cutting force and machined pattern was analyzed. Based on the analysis, the critical thrust force was quantitatively determined, and then the silicon was machined at a force lower than the critical thrust force. The machined pattern was observed using SEM and AFM to check for the occurrence of brittle fractures. Finally, the sharp V-shaped nano-pattern was manufactured on the single crystal silicon.

• Journal of the Korean Geotechnical Society
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• v.31 no.2
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• pp.65-73
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• 2015

The bank revetment work which is conducted on the slope of river bank to protect against flowing water as a geotechnical structure has been applied as an average value of critical tractive force based on domestic and international standard design. Currently, an appropriate evaluation is needed for the hydraulic stability and geotechnical behavior analysis of bank revetments because of the effects of climate change and ambiguous design criterion. This study has compared the critical tractive forces of soil improvement material and conventional materials used for the bank revetment work. Through various experiments, the shear strength of mixtures with soil improvement material was investigated by curing time and mixture ratio. It was found that the critical tractive force of the mixture obtained from a scour test is suitable to the reinforcement of the slope of river bank which has problems such as seepage erosion and scour.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.788-792
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• 2003

Rotating machines are widely used in industrial world and especially motor and generator take up much part of it. As for this kind of motor and generator, electrical loss due to eddy current is the very important factor and that is also a primary factor causes heat generation. To solve this kind of problem like the above. insulated laminating silicon steel sheet is used to prevent eddy current effect. Laminated rotor is widely used as rotating shaft of motor and generator. Due to that, electrical loss and heat problem can be solved but designer meets another problem. In general. most of the motor and generator can be normally operated under 3,600 rpm because they are designed to have the first critical speed more than that speed. But nowadays, they should be operated more than the first critical speed as usual with the trend of high speed, large scale and high precision in industrial world. The critical speed can be determined from the inertia and stillness for the rotor and bearing of rotating systems. The laminated rotor stiffness can be hardly determined because it can be derived a lot factors for instance rotor material and shape, lamination material and shape, insulation material. lamination force and so on. In this paper, the change of the natural frequency of the motor was examined with the change of the lamination force as an experimental method and design criteria will be presented for motor & generator designer, who can apply the result of numerical analysis with equivalent diameter scheme with ease.

• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.3
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• pp.3114-3118
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• 1973

• Proceedings of the Korea Water Resources Association Conference
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• 1985.07a
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• pp.137-154
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• 1985

• Structural Engineering and Mechanics
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• v.60 no.2
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• pp.193-209
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• 2016

In this study, wave force tests were carried out for the four types of offshore support structures with scale factor 1:25 and wave forces to the support structure shapes were investigated. As the results of this study, it was found that, as the wave period increased at the normal wave condition, wave force decreased for the most cases. Extreme wave force was affected by the impact wave force. Impact wave force of this study significantly effect on Monopile and slightly on GBS and Hybrid type. Accordingly, Hybrid type indicated even lower wave force at the extreme and irregular wave conditions than the Monopile although Hybrid type indicated higher wave force at the normal wave condition of the regular wave because of the larger wave area of wave body. In respects of the structural design, since critical loading is extreme wave force, it should be contributed to improve structural safety of offshore support structure. However, since the impact wave force has nonlinearity and complication dependent on the support structure shape, wave height, wave period, and etc., more research is needed to access the impact wave force for other support structure shapes and wave conditions.

• Transactions of Materials Processing
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• v.6 no.6
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• pp.482-488
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• 1997

New carbon equivalent equation for the better prediction for the better prediction of roll force in a continuous hot strip mill has been formulated by applying a neural network method. In predicting roll force of steel strip, carbon equivalent equation which normalize the effects of various alloying elements by a carbon equivalent content is very critical for the accurate prediction of roll force. To overcome the complex relationships between alloying elements and operational variables such as temperature, strain, strain rate and so forth, a neural network method which is effective for multi-variable analysis was adopted in the present work as a tool to determine a proper carbon equivalent equation. The application of newly formulated carbon equivalent equation has increased prediction accuracy of roll force significantly and the effectiveness of neural network method is well confirmed in this study.