• Transactions of the Korean Society of Mechanical Engineers
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• v.6 no.3
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• pp.261-270
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• 1982

In the previously reported Part I and Part II, the experimental results in the frictional machining under liquid atmospheres to obtain the best surface roughness were showed. In the present study the frictional machining was carried out in gas atmospheres such as air, oxygen, dioxide carbon and argon, and in solid lubricant atmosphere of graphite powder. The results were compared with those of Part I and Part II. The material to be tested and machining conditions were made identical with Part I and Part II. The best surface roughness obtained in the above gas and solid lubricant atmospheres was worse than the liquid atmospheres but the contact pressure to minimize the surface roughness was considerably low. The best surface roughness in the present study was obtained in the atmospheres of dioxide carbon and graphite powder and the worst one was in oxygen and argon gas.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.2
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• pp.71-75
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• 2006

The aggregates made of clay, carbon and $Fe_2O_3$ were prepared to investigate the mechanism of black core formation and the property differences at various sintering atmospheres. The aggregates were sintered at oxidized, neutralized and reduced atmospheres. The specific gravity, absorption rate, percent of black core area were measured at various compositions and sintering atmospheres. The aggregates sintered at oxidized atmosphere showed clear border between shell and black core area. Hence, the aggregates sintered at reduced and neutralized atmospheres showed only black core area in the cross-section of the aggregates. The specific gravity of the aggregates sintered at reduced atmosphere increased with increasing carbon contents and that was the lowest of all aggregates sintered at various atmospheres. Adsorption rate increased with increasing carbon contents at all atmospheres.

• Journal of The Korean Astronomical Society
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• v.42 no.3
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• pp.47-54
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• 2009

In this paper we present an independent FORTRAN code for calculating LTE-plane-parallel model atmospheres. The transfer equation has been solved using Avrett and Loeser method. It is shown that, using an approximate non-gray temperature distribution together with the iteration factors method (Simonneau and Crivellari) for correcting the temperature distribution reduce the number of iteration required to achieve the condition of radiative equilibrium. Preliminary results for pure helium model atmospheres are presented.

• Journal of Korean Institute of Fire Investigation
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• v.5 no.1
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• pp.25-28
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• 2004

Since the very first use of optical systems in the process industries there has been a tacit assumption that, because they are not electrical, they do not present an ignition risk when used in flammable atmospheres. This paper describes about an optical ignition mechanism from experimental work carnied out by Sira Safety Services Limited(UK) and whether there is sufficient of an ignition risk for precautions to be advisable when optical systems are used in flammable atmospheres.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2001.11a
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• pp.79-82
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• 2001

The studies of the radiation-induced ignition of combustible atmospheres are of particular importance due to increasing use of optical sensors in industries such as coal mining and petroleum production. Because of the alleged intrinsic safety of such systems, substantial optical power is transmitted through optical fibers in potentially explosive atmospheres. However, there has been little experimental or theoretical research on the safety of optical power delivered by optical fiber systems in combustible atmospheres.(omitted)

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.818-819
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• 2006

The effect of individual gas constituents in a sintering atmosphere is examined to optimize the sintered properties of Iron-Carbon P/M components. The influence of sintered properties is reviewed as a function of hydrogen percentages and dew point in the sintering zone. Microstructures, porosity, pore morphology and dimensional changes are the subject of this review. The effects of CO containing atmospheres are compared against the non CO atmospheres in terms of hardness, carbon control and dimensional changes.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.251-258
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• 1997

The detection of jovian hydrogen-hydrogen dimers through the clear telluric 2-micron window(Kim et al. 1995, Trafton et al. 1997( suggests possibility to detect noble gases in the form of dimer with hydrogen in jovian atmospheres. Since noble noble gases do not have spectral structures in the infrared, it has been difficult to derive their abundances in the atmospheres of jovian planets. If there is a significant component of noble gases other than helium in the jovian atmospheres. it might be detected through its dimer spectrum with hydrogen molecule. The relatively sharp spectral structures of hydrogen-argon and hydrogen-neon dimers compared with those of hydrogen-hydrogen dimers are useful for the detection, if an adequate signal-to-noise (S/N) is obtained. If we use a large telescope, such as the Keck telescope, with a long exposure time (>24 hours), then $H_2-Ar$ spectral structure may be detected.

• Journal of Astronomy and Space Sciences
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• v.18 no.2
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• pp.95-100
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• 2001

We have presented an ab initio model of the $2{mu}m$ spectral features of $(H_2)_2$ based on the far-infrared models of McKellar & Schaefer (1991). We have shown that the intensity variations of the $2{mu}m;(H_2)_2$ features depend on the ortho/para ratios of $H_2$ We have discussed the applicability of the variations to the atmospheres of the giant planets for the derivations of the ortho/para ratios. The signal to noise ratios of currently available spectra of the giant planets are not sufficient enough to derive accurate ortho/para ratios of these planets. Observations with longer exposure times and larger telescope apertures are required to obtain better spectra for the derivations of the ortho/para ratios of $H_2$ in the atmospheres of the giant planets.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.31-38
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• 2000

We have presented detected molecules, atoms, radicals, ions, and dimers in the atmospheres of planets and comets from Earth-based and spaceborne observatories during the last 3 decades. We have reviewed spectroscopic studies on the auroral emissions and air glows of the giant planets, and briefly summarized spectroscopic observations of dimers in the atmospheres of the giant planets and Titan. In particular, we highlighted the recent detections of new molecular emissions and absorptions in the spectra of the giant planets, Titan, and recent bright comets from spaceborne or ground-based observatories. We also reviewed current models and theories of the origin and evolution of the solar system, and implications of isotopic ratios in these atmospheres.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.4
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• pp.338-346
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• 1981

Honing, lapping, polishing and superfinishing are applied for a precision machining to finish the metal surface, but these precision machining are micro-cutting by hard and micro-abrasive grains. Frictional machining is the new method to finish mirrorlike surface without using those abrasive grains. The frictional machining produces high pressure and high temperature instantly by compressing a tool material against the metal surface in sliding motion. The metal surface is given plastic deformation and plastic flow by the above mentioned frictional motion, but the surface roughness of the metal surface is influenced by physical and chemical reaction in surrounding atmosphere. Therefore, the atmosphere around the metal optimum atmosphere in the frictional machining. The part 1 of the study was performed in liquid atmospheres. Diesel oil, lubricant, grease, lard oil, bean oil and cutting fluid were used as such atmospheres. Medium carbon steel SM 50 C was used as a workpiece and ceramic tip was applied as a frictional tool. The result of the experiment showed characteristic machining conditions to generate the best surface roughness in each atmospheres.