• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.198-203
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• 1999

In this study, chip-tool friction and shear characteristics of cold drawn free machining steels in turning were assessed. To do this, a newly developed equivalent oblique cutting model was adopted. And for comparison with those of free machining steels, chip-tool friction and shear characteristics of conventional carbon steels were also investigated. The Pb-S free machining steel shows superior machinability to others. In case of the Bi-S free machining steel, the shear stress and the specific friction energy are relatively lower than those of conventional carbon steels, but its shear strain is relatively high, so it does not show any remarkable improvement of machinability.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.3
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• pp.90-96
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• 2001

Experimental investigations were carried out to find the characteristics of grinding of ceramics. Grinding mechanisms of ceramics were inspected through the microscopic examination. It has been found that the specific grinding energy of ceramics is relatively low as compared to that of steels. The specific grinding energy affects the surface roughness and the residual stress of ground surface. the experimental results indicate that the rougher surface finish and higher compressive residual stress are obtained at lower specific grinding energy. The surface roughness and the residual stress of the ground surface have significant effects on the strength of ground piece of ceramics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1032-1035
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• 1997

The purpose of this paper is to reduce the number of cutting tests and to predict the main cutting force and the specific cutting energy. By using the SOFM neural network, the most suitable cutting test conditions has been found. As a result, the number of cutting tests has been reduced to one-third. And by using MLP neural network and regression analysis, the main cutting force and specific cutting energy has been predicted. Predicted values of main cutting force and specific cutting energy are well concide with the measured ones.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.337-342
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• 2000

Experimental investigations were carried out to find the characteristics of grinding of ceramics. Grinding mechanisms of ceramics were inspected through the microscopic examination. It has been found that the specific grinding energy of ceramics is relatively low as compared to that of steels. The specific grinding energy affects the surface roughness and the residual stress of ground surface. The experimental results indicate that the rougher surface finish and higher compressive residual stress are obtained at lower specific grinding energy. The surface roughness and the residual stress of the ground surface have significant effects on the strength of ground piece of ceramics.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.17-24
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• 2004

In end milling process, undeformed chip thickness and cutting forces vary periodically with phase change of the tool. Recently, a model has been proposed to simulate the shear and friction characteristics of an up-end milling process in terms of the equivalent oblique cutting to this. In the current study, a down-end milling process has been replaced with the equivalent oblique cutting process. And shear and tool-chip friction characteristics variation of SM45C steel has been studied using the end-mills of different helix angles. The specific shear and friction energy consumed with helix angle of $50^{\circ}$ is somewhat larger than those of$30^{\circ}$ and $40^{\circ}$. The specific shear energy consumed is about 76-77% of the specific cutting energy regardless the helix angles.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.63-68
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• 1987

In this study, a pantograph leg of the four legged walking vehicle is analysed with regard to mechanical energy consumption. Energy efficiency of the vehicle is estimated in terms of specific resistance varying body height, stride length and walking speed. The interaction between specific resistance and the parameters is investigated.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.468-473
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• 2010

The purpose of this study is to derive the correlation between the Specific Phosphorus Release Rate (SPRR), Specific Phosphorus Uptake Rate (SPUR) and Specific Oxygen Uptake Rate (SOUR) at various Sludge Retention Time (SRT) condition in the A/O process. The laboratory scale reactor was operated on various SRT (10 day, 20 day, 30 day, 40 day). In this study, the SPRR, SPUR and SOUR tended to decrease with the SRT increase. Empirical equations was be obtained $y=4.54E-006x^2+0.0007x-0.0315$, $R^2=0.925$ (SOUR vs. SPRR) and $y=3.22E-006x^2+0.0004x-0.0173$, $R^2=0.928$ (SOUR vs. SPUR) from the relationship between SRT, SPRR and SPUR and SOUR. Therefore, the anaerobic tank design based on the research result such as SPRR, SPUR of a phosphorus design and SOUR would be possible.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1768-1775
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• 2004

The compressive axial collapse tests were performed to investigate collapse modes and energy absorption characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP(Carbon Fiber Reinforced Plastics) outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different CFRP orientation angles. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, specific energy absorption were the highest for Al/CFRP, CFRP in the middle, and aluminum the lowest. Also, specific energy absorption of circular tubes was higher than square tubes'. It turned out that CFRP orientation angle of Al/CFRP compound tubes influence specific energy absorption together with the collapse modes of the tubes.

• Journal of Energy Engineering
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• v.19 no.1
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• pp.1-7
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• 2010

This experimental study suggests some alternatives for stable growth and environmental conservation, responding to the unstability of global energy market and the regulations to greenhouse gas reduction. It introduces the energy-chain approach optimizing the whole processes extending energy production, transfer, and exploitation. And the alternatives are covered from low-carbon & environment-friendly energy-specific innovation system, transformation of major industries to low-carbon & environment-friendly industries, upgrading of energy efficiency, procurement of energy sources to policy cluster.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.305-309
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• 2001

Site-specific atmospheric dispersion characteristics have been analyzed. The northwest and the southwest wind prevail on nuclear sites of Korea. The annual isobaric surface averaged for twenty years around Korean peninsula shows that west wind prevails. The prevailing west wind is profitable in the viewpoint of radiation protection because three of four nuclear sites are located in the east side. Large scale field tracer experiments over nuclear sites have been conducted for the purpose of analyzing the atmospheric dispersion characteristics and validating a real-time atmospheric dispersion and dose assessment system FADAS. To analyze the site-specific atmospheric dispersion characteristics is essential for making effective countermeasures against a nuclear emergency.