• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.58.4-59
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• 2017

Sanduleak's star is a suspected symbiotic binary located in the Large Magellanic Cloud. It is known that it has a giant jet with physical size ~ 14pc. Its spectrum shows two strong emission bands at $6825{\AA}$ and $7082{\AA}$, which are originated from Raman-scattering of O VI by neutral hydrogen atoms. We present the high-resolution spectrum of Sanudleak's star obtained with MIKE at the Magellan-Caly telescope to investigate the O VI emission region based on the profiles of the two Raman features. In this spectrum, it is noted that the Raman $6825{\AA}$ feature exhibits a single broad peak profile, which is in high contrast with a clear triple peak profile of the Raman $7082{\AA}$ feature. In our analysis we suggest that the O VI emission region consist of three main emission parts: an accretion disk, a bipolar outflow and an optically thick, compact component surrounding the white dwarf. By performing Monte Carlo simulation we constrain the representative column density of the H I scattering region N_HI ~1${\times}$10^23 cm^-2, which is in accordance with the observed flux ratio in the two Raman features F(6825)/F(7082) ~ 4.5.

• Journal of The Korean Society of Grassland and Forage Science
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• v.14 no.3
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• pp.223-229
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• 1994

To find out the effects of phosphatic fertilizer application levels on the botanical composition, mineral contents and mineral nutrient deprivation of grasses and the chemical properties of soil, this expriment was arranged as a randomized complete block design with six treatments(0, 50, 100, 150, 200 and 250kg $P_2O_5$/ha) and conducted at hilly land in Gwangju, Gyeonggi Province from September, 1989 to October, 1992. The results obtained are summarized as follows: The botanical composition of grasses without posphatic fertilizer application was poor but with 150kg $P_2O_5$/ha application, remarkably increased in legume of grasses and decreaed in weed. As the phophatic fertilizer levels increase, P, Ca and Mg content of grasses were increased but N and K content tended not to be regular, and Ca/p and K/Ca+ Mg equivalent ratio were lowered. Up to 150kg $P_2O_5$/ha application level, the mineral nutrient content deprived by dry matter yield was increased but with that over application, tend not to be increased. Most of applied mineral elements were accumulated at a subsurface of grassland and as the phosphatic fertilizer application levels increase, the available $P_2O_5$ and exchangeable Mg contents of the soil tended to be remarkably increased and exchangeable K content tended to be decreased, but pH, OM and exchangeable Ca content tended not to be regular.

• Journal of the Korean institute of surface engineering
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• v.41 no.1
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• pp.38-42
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• 2008

316L stainless steel welding tube was electrolytically polished and the inner surface characteristics of the tube were tested. Electro-polishing variables such as current, voltage, concentration of electrolyte and electropolishing time were changed to seek for optimum condition. These makes a optimum conditions for the electro-polishing as 4000 A, 9 V, 1.7 specific gravity of electrolyte, and 30 minute of electro-polishing time. It makes the surface roughness as Ra < $0.25{\mu}m$. XPS test resulted as the ratio of CrO/FeO equals or more to 3/1. AES test resulted as the thickness of CrO film of $38{\AA}$. DTA test resulted as the tube did not react with $N_2,\;H_2\;and\;O_2$ gas below 1073K. As summarize above results, the electro- polished 316L stainless steel welding tube satisfied the conditions to apply as a pipeline for semi- conductor production facility and clean room.

• Journal of Information Display
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• v.2 no.4
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• pp.29-33
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• 2001

The luminance and discharge characteristics of an AC PDP may be significantly affected by a small amount of impurity gas in working gas. Impurity gases such as $O_2$, O , C and $H_2$ can be mixed in the manufacturing and lor discharge processes. In this paper, a small amount of impurity gas in AC PDP are introduced intertimally and the relationship between the amount of impurity gas and the luminance/discharge characteristics are investigated. The luminous efficiency decreased seriously with the increase in the partial pressure of impurity gases, especially in $H_2$, $O_2$ and $CO_2$, Under the condition of the impurity gas ratio of 2x $10^{-3}$ for Ar, $N_2$, $H_2$, $CO_2$ and $O_2$, the luminous efficiency decreased to about 8%, 8%, 32%, 36% and 50%, respectively.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1712-1715
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• 2018

To study the applications for ferroelectric non-volatile memory and ferroelectric memristor, etc., deposition pressure dependent electric the properties of $(Hf,\;Zr)O_2$ thin films by RF sputtering deposition method were investigated. The bottom electrode was TiN thin film to produce stress effect on the formation of orthorhombic phase and top electrode was Pt thin film by DC sputtering deposition. Deposition pressure was varied along with the same other deposition conditions, for example, sputtering power, target to substrate distance, post-annealing temperature, annealing gas, annealing time, etc. The structural and electric properties of the above thin films were investigated. As a result, it is confirmed that the electric properties of the $(Hf,\;Zr)O_2$ thin films depend on the deposition pressure which affects structural properties of the thin films, such as, structural phase, ratio of the constituents, etc.

• Textile Coloration and Finishing
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• v.33 no.4
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• pp.238-249
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• 2021

In this study, the effect on flame retardancy and various physical properties when TiO₂ was added with a citric acid/phosphate complex acid catalyst together with Pyrovatex CP new (N-methylol dimethylphosphonopropionamide), a phosphorus-based flame retardant, was studied on cotton fibers. SEM-EDS analysis was performed to confirm the surface characteristics and surface element analysis of the flame-retardant treated cotton fibers, and a vertical carbonization test was performed to confirm the char formation capability and flame retardancy according to the phosphoric acid ratio. By comparing the LOI index before and after washing 10 times, the washing durability of the flame retardant solution containing the phosphoric acid catalyst and TiO₂ was tested by LOI index after ten washing cycles. In addition, the influence of the flame-retardant processing on the physical properties were compared including thermogravimetric analysis (TGA), tear strength and whiteness.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.149-152
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• 2002

SrZrO3 resistive oxide barriers on Ag sheathed Bi2223 tapes prepared by the sol-gel and dip coating method were evaluated with an aid of Taguchi method and orthogonal arrays to elucidate the effects of experimental parameters, such as ratio of starting solution, amount of additives, and heat treatment temperature and time on the properties of the thin films. Six experimental parameters were selected and then Ll8(21x37) orthogonal arrays were constructed. Finally, SEM and XRD results were related to signal to noise (S/N) ratio to evaluate the optimized experimental condition.

• Journal of Ocean Engineering and Technology
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• v.4 no.1
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• pp.87-87
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• 1990

Fatigue crack closure levels based on the behavior of residual displacements on crack surfaces, are determined analytically according to the microscopic crack closure mechanisms, i.e., whether the first contact of crack surfaces takes place at the very crack tip or on the surfaces near the tip. The comparative analysis on the two models is carried out empirically by the constant amplitude fatigue tests on 2024-T3 aluminum alloy plate, and it shows that under negative stress ratio, the case of the first contact at crack tip gives better agreement with the experimental results than the other.

• Journal of the Korean Society of Combustion
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• v.22 no.4
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• pp.51-56
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• 2017

The decomposition of tetrafluoromethane has been investigated with the reaction mechanism proposed for freely propagating $CH_4/CF_4/O_2/N_2$ premixed flames on the oxygen enrichment. The factors affecting on the removal efficiency of tetrafluoromethane were analyzed. The increase in flame temperature due to oxygen enrichment has a great influence on the removal efficiency of tetrafluoromethane. At the same oxygen enrichment condition, the removal efficiency in the rich flame is higher than one in the lean flame. The increase of the F/H ratio leads to decrease the flame temperature and the removal efficiency of tetrafluoromethan is decreased at the flame temperature of 2600 K or lower, The elementary reactions that dominate the consumption of tetrafluoromethane are (R1) $CF_4+M=CF_3+F+M$ and (R2) $CF_4+H=CF_3+HF$. (R1) has the greatest effect on the consumption of tetrafluoromethane under the oxygen enhanced flames.

• Journal of Ocean Engineering and Technology
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• v.2 no.1
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• pp.176-182
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• 1988

The exergy analysis on the heat storage performance of the senible heat storage unit which consists of the heat storage material in the concentric annulus and the hot fluid flowing through the inner tube is performed. Heat transfer characteristics which are necessary for the performance of the exergy analysis is obtained from the energy balance equations and the second law of thermodynamics. As the index of heat storage performance, the exergy lossnumber $N_{s}$, and exergy storage ratio from the concepts of the second law of thermodynamics are defined. Results are ovtained for the grometry of the storage unit, the Biot number Bi, ambient temperature $T_{o}$ as parameters. From these results the exergy storage ratio can be considered as the efficiency of the hat storage unit and is introduced as a guide to design.