• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2578-2582
• /
• 2008

In predicting the critical heat flux (CHF) in pool boiling systems, the contact angle between the boiling surface and the liquid and the surface roughness are considered to be the important parameters. From the microscopic viewpoint, those are affected by the micro/nano structure of the surface. Several studies have been reported on the dependence of CHF on the surface microstructure such as height and width of the cavities and distances between them. In this paper, the effects of the boiling surface characteristics on CHF are reviewed and the future research issues are discussed for better prediction of CHF.

• Journal of the Semiconductor & Display Technology
• /
• v.7 no.1
• /
• pp.53-57
• /
• 2008

$Pb(ZrTi)O_3$ thin films were prepared on transparent conducting oxides, through sol-gel processing. The processing variables such as spin velocity, spin time and annealing temperature were investigated using a statistical design of experiments. Dielectric properties were determined through capacitance-voltage measurements and electrical characterizations evaluated using current-voltage characteristics. The leakage currents is determined mainly by annealing. The capacitance and breakdown voltage is found to be independent of the processing variables. The sophisticatedly controlled PZT thin films have been confirmed through microscopic images.

• YAKHAK HOEJI
• /
• v.39 no.6
• /
• pp.593-599
• /
• 1995

Erythromycin was formulated as enteric-coated pellets in order to reduce degradation in stomach and gastromtestmal irritation, and to maximize the absorption in intestine followmg its oral administration. Core pellets were prepared using fluid-bed granulator with two different methods (powder layering and solvent spraying) and enteric-coated with two different coating polymers (HPMCP and Eudragit E30D). Physical characteristics md dissolution rates of core pellets and enteric-coated pellets were evaluated to optimize the formulation. Powder layering method resulted in shorter initial dissolution time than solvent spraying method, but physicochmical properties of the product were worse than solvent spraying method with respect to hardness, ftiability and density. The dissolution rate of the drug was increased with the addition of surfactants, showing concentration-dependence. The scanning electron microscopic observation of pellets revealed significant differences on the surface appearances prepared with solvent spraying method. The core pellet made with powder layering method had crystals on the surface, which resulted in poor physical properties of the pellets. The dissolution profiles of erythromycin pellets coated with HPMCP or Eudragit L30D were close to that of commercially available erythromycin enteric-coated product.

• Journal of ILASS-Korea
• /
• v.3 no.4
• /
• pp.16-24
• /
• 1998

The fuel injection type, in the gasoline engines of atomization of fuel droplet and its distribution hae influenced directly on the decision of engine performance and harmful emission. In this paper, atomization characteristics of fuel spray is investigated with microscopic visualization system. Particle motion analysis system is used to measure the SMD from fuel spray of air-assisted injector by initial factors such as temperature of ambient air and air-assisted pressure. As air-assist pressure and ambientair temperature increase, the SMD is decreased, and its variation is more stable.

• Microbiology and Biotechnology Letters
• /
• v.24 no.5
• /
• pp.591-596
• /
• 1996

In the course of screening lipid peroxidation inhibitor from basidiomycetes, a mushroom, which was collected at O-Dae mountain in Kangweon- Do, was found to have active compound. The mushroom was identified as Polyzellus multiplex, which belongs to Aphylloporalles Thelephoraceae, on the basis of macroscopic and microscopic characteristics of the fruiting body. The methanol extract of fruiting body was extracted with benzene and ethylacetate, sequentially. By using various kinds of chromatographies, PM1, and PM2 and PM3, were purified from the ethylacetate extract and the benzene extract, respectively. Color reaction and analyses of IR, UV, and NMR spectra indicated that PM1 was a derivative of thelephoric acid, and PM2 and PM3 were linoleic acid and oleic acid, respectively. IC$_{50}$ of PM1 for inhibition of lipid peroxidation was 1.96 ppm and LD$_{50}$ was 500 mg/kg.

• 한국연소학회:학술대회논문집
• /
• 2013.06a
• /
• pp.69-72
• /
• 2013

This study investigates the characteristics of biochar by slow pyrolysis at $500^{\circ}C$ for various biomass residues. Six biomass materials were tested: Tree bark, Tree stem, bagasse, cocopeat, paddy straw and palm kernel shell. In the biochar yield, the effect of ash in the raw biomass was significant for paddy straw. Excluding the ash content, the timber bark, bagasse and paddy straw had a similar biochar yield of 26-29 wt.%. Tree stem and bagasse had well developed pores in a wide size range and large surface area over $200m^2/g$. Cocopeat and PKS has significantly higher biochar yield due to the increased content of lignin, but the development of intra-particle pores and microscopic surface area was very poor. The elemental composition, pH and other properties of the biochar samples were also compared.

• Journal of Biosystems Engineering
• /
• v.17 no.2
• /
• pp.132-142
• /
• 1992

The main objective of this paper is to evaluate and modify the existing algorithms for the automatic threshold selection. Four existing algorithms were evaluated quantitatively using test images of coffee droplets and an apple. The images had the different area ratio of the object to the image size, different average gray values between the object and the background, and different S/N ratio of the Gaussian noise. The result showed that Histogram Clustering Method and Maximum Entropy Method were better than Moment Preserving Method and Simple Image Statistic Method in automatic thresholding.

• Journal of Chest Surgery
• /
• v.29 no.11
• /
• pp.1281-1283
• /
• 1996

We describe the case of a 58-year-old woman who has coexisting intrapulmonary and mediastinal leiomyomas. Initially, she was seen with a single mass in the right lower hilar area in a simple chest roentgenogram. But computed tomography demonstrated another mass in the right posterior mediastinum. Microscopic examination and immunohistochemical staining of the resected specimens showed the characteristics of the leiomyoma.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2000.11a
• /
• pp.310-317
• /
• 2000

Tribological properties of friction materials containing different volume ratios of solid lubricants (graphite and MoS$_2$) were studied using a pad-on-disk type friction tester. Morphology and thickness of the friction film were carefully examined to correlate the friction performance with the property of the friction film. Results showed that the friction materials containing 16vo1. % of graphite and 5 vol. % of MoS$_2$exhibited best friction stability among others. In particular, the thickness of the friction film decreased as the amount of MoS$_2$increased and severe friction oscillation was observed when the friction material contained MoS$_2$only (21 vol. %). Microscopic observations and friction tests suggested that the coherent thick transfer film improved the friction stability.

• Journal of Veterinary Clinics
• /
• v.25 no.6
• /
• pp.466-470
• /
• 2008

The purpose of this study is to investigate whether the effects of topically applied petrolatum and glycerin on the barrier repair of acetone-induced skin damage in 6 beagle dogs. To confirm the effects of petrolatum and glycerin on acetone disrupted skin models, we performed to evaluate the characteristics of transepidermal water loss and SC hydration and scanning electron microscopic observations. TEWL and SC hydration measurements were carried out 3, 6, 12, 24, 48h after applying petrolatum and glycerin during recovery from acute disruption. Our results showed that there were some different effects between petrolatum and glycerin on the acetone damaged skin such as barrier function repair process and SC hydration status. The results indicate that the significant improvement could be observed in glycerin apply more than petrolatum after acetone damages, and further study will be required.