• Proceedings of the Korean Nutrition Society Conference
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• 1995.05c
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• pp.21-21
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• 1995

Absorption of fat-soluble vi tamin, retinol occurs mainly in the proximal part of small intestine. But its intestinal transport mechanism isn't yet clear. The aim of the present study was to investigate on the mechanism of absorption of retinol by determining a concentration-dependent kinetic of retinol absorption in rats. The study was carried out by applying in vivo technique in which vitamin solution was infused to intestinal lumen and at the same time thoracic duct and choledochus duct were canulated to collect samples. The investigations showed that retinol is absorbed in the small intestine by a saturable, carrier-mediated transport system, i.e. wi thout signi ficant differences between the proximal and distal halves of the small intestine. The transport of retinol taken up by the enterocytes occured via different mechanisms: while the main vitamin A transport via the thoracic duct was saturated by limiting transport factors such as retinol-CRBP-II-complex formation and retinol esterification with increasing substrate concentrations, the transport of retinol metabolite product via the portal vein was proportional to the substrate concentration.ration.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.392-397
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• 2000

Mono-disperse particles generated by a condensation particle generator are widely used to meet the experimental and industrial needs. The characteristics of particles generated by homogeneous nucleation have been studied experimentally using a laminar flow condensation particle generator. Dry nitrogen gas saturated with oleic acid vapor was cooled well below the saturation temperature causing the highly supersaturated vapor to nucleate. The dependence of GSD(Geometric Standard Deviation), GMD(Geometric Mean Diameter), and the mass concentration of particles on the temperature at the evaporator, flow rate and the temperature condition at condenser was studied. The experimental results show that the mass concentration of particles is affected by the radial temperature profile at condenser. Nucleation at the center of the condenser causes the mass concentration of particles to increase. The experimental results also show that the suppression of additional nucleation by a constant temperature condition at the condenser increases the mean diameter of particle.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.2
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• pp.150-156
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• 1997

The effect of variation of pack activators, compositions, temperature and time on the thickness and structure of aluminide coatings formed on the TiAl alloy was studied in one-step packs and two-step packs containing aluminum for the purpose of improvement of oxidation resistance. The thickness of coating layer was increased with increasing $NH_4Cl$ content up to 3wt% and then it was saturated. Oxidation resistance of coating layers carried out at one step pack was superior to that of ones through of two step pack. The improvement of high temperature oxidation resistance was due to the formation of a protective $Al_2O_3$ surface layers and coating the alloys with $TiAl_3$ phase.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.418-418
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• 2012

We fabricated a new type of hybrid film using molecular layer deposition (MLD). The MLD is a gas phase process analogous to atomic layer deposition (ALD) and also relies on a saturated surface reaction sequentially which results in the formation of a monolayer in each sequence. In the MLD process, polydiacetylene (PDA) layers were grown by repeated sequential surface reactions of titanium tetrachloride and 2,4-hexadiyne-1,6-diol with ultraviolet (UV) polymerization under a substrate temperature of $100^{\circ}C$. Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of the hybrid films. Polymerization of the hybrid films was confirmed by infrared (IR) spectroscopy and UV-Vis spectroscopy. Composition of the films was confirmed by IR spectroscopy and X-ray photoelectron (XP) spectroscopy. The titanium oxide cross-linked polydiacetylene (TiOPDA) hybrid films exhibited good thermal and mechanical stabilities.

• Nuclear Engineering and Technology
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• v.41 no.10
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• pp.1285-1292
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• 2009

The effects of the narrowed upside gap on nucleate pool boiling heat transfer in a vertical annulus were investigated experimentally. For the study, a stainless steel tube with a diameter of 25.4 mm and saturated water that kept an atmospheric condition were used. The ratio between the gaps measured at the upper and the lower regions of the annulus ranged from 0.18 to 1. Two different lengths of the modified gap also were investigated. The change in heat transfer due to the modified gap became evident as the gap ratio decreased and the length of the gap increased. As the gap ratio became less than 0.51, a significant decrease in heat transfer was observed compared to the plain annulus. The longer gap size resulted in an additional decrease in heat transfer. The major cause for the tendency was attributed to the formation of lumped bubbles around the upper region of the annulus followed by the increased flow friction between the fluid and the surface around the modified gap.

• KSBB Journal
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• v.8 no.4
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• pp.397-404
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• 1993

Two strains were isolated from the vinegar of Korean traditional fermented rice wine and the vine gar of fermented persimmon, respectively. These strains, designated as KM and BPV, were identified as the genus Acetobacter with respect to morphological, physiological, and biochemical characteristics. The Isolates oxidized ethanol to acetate and over-oxidized acetate or lactate to CO2 and H2O. They were positive in catalase test, while being negative in oxidase, gelatin liquefaction, VP test, H2O production and indole formation tests. No ${\gamma}$-pyrones ware produced from glucose and fructose. KM was tolerant of 11% ethanol while BPV was relatively sensitive to ethanol at a higher concentration than 5%. The guanine-plus-cytosine contents of the DNA of KM and BPV strains were 53.8 and 56.6 mol%, respectively. The cellular fatty acid compositions contained in these isolates were saturated straightchain C14:0 and C16:0,, and unsaturated straight-chain C18:1. Major ubiquinone system of KM was Q-9, but that of BPV was Q-10. In morphophysiological and biochemical aspects, KM strain was similar to Acetobacter pasteurianus. However, BPV strain was different from other Acetobacter type strains.

• Journal of The Korean Astronomical Society
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• v.45 no.6
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• pp.157-166
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• 2012

Using the Submillimeter Array (SMA), we identified two bright hot subcores, MM1a and MM1b (size ~ 1" and mass ~ 0.5 $M_{\odot}$) separated by about 1.600, in the 230 GHz continuum emission toward the massive star-forming region DR21(OH). Both display typical hot core characteristics but have slightly different chemical properties. For example, highly saturated species show stronger emission toward MM1a and seem to be evaporating directly from the grain mantles. In contrast, simple sulfur-bearing species have brighter emission at MM1b. These features indicate that MM1a is at an earlier stage than MM1b, and the small-scale chemical differences between these two cores may result from the age difference of the order of $10^4$ years.

• Journal of the Korean Ceramic Society
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• v.37 no.8
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• pp.774-780
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• 2000

In order to improve luminescence prperty of phosphors, we have synthesized Zn2SiO4:Mn phosphors by a new chemical synthetic route, i.e., the homogeneous precipitation method. This method has featured that the formation of phosphoris completed at relatively low temperature of 105$0^{\circ}C$ and the particle morphology exhibits spherical shape to be well-dispersed and uniform size. At all the Mn concentration explored, phosphors prepared by this method have exhibited the improved emission intensities. In particular, the emission intensities of phosphors with Mn doping contents between 1 at% and 3.5 at% were higher about 40% than that of commercial phosphor. On the other hand, the decay time has been decreased from 23 ms to 11 ms with increasing Mn concentration. In addition, the phosphor composition containing 3 at% Mn has displayed the most saturated color.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.6
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• pp.199-204
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• 1983

In this paper, we investigated that the Al-Amorphous Se-Al structure had a large photovoltage and a Dark EMF (DEMF). This DEMF phenomena did not show just after the fabrication of a sample. However, it was shown after a few days, and it was increased with time, and was saturated after 30 days. Just after the fabrication of a sample, by appling the positive voltage on a sample for 100mins, we observed almost the same effect as had shown in a aging experiment. As the results, we found that Al3+ ions has related to a DEMF by migrating into amorphous Se, and form a trap in amorphous Se. We have also observed the photocapacitance effect to identify this trap formation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.105-106
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• 2008

Nanotube morphology change of Ti-Ta-Zr alloy as Zr content increase has been researched using various experimental methods. Ti-Ta-Zr(3, 7 and 15 wt%) alloys were prepared by arc melting and nano-structure controlled for 24 hr at $1000^{\circ}C$ in argon atmosphere. Formation of oxide nanotubes are conducted by anodizing a Ti-Ta-Zr alloy in $H_3PO_4$ electrolytes with small amounts of fluoride ions at room temperature. Electrochemical experiments were carried out with conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. The samples were embedded with epoxy resin, leaving a square surface area of $10mm^2$ exposed to the anodizing electrolyte, 1.0M $H_3PO_4$ containing 0.8wt% NaF.