• The Korean Journal of Ceramics
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• v.2 no.4
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• pp.251-256
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• 1996

Effect of mixed grinding with a planetary ball mill of starting materials before heat treatment on the crystal structure and superconduction properties in the YBaCu composite oxide was studied. The size reduction of powders too place in the early stage of grinding, followed by aggregation of the resultant fine particles. The uniformity of the composition in the mixture was improved with grinding, which later decreased in the crystal grain size and well distribution of twin phase in the sintered bodies. The critical current density of the sintered bodies obtained from the mixture ground for 60 minutes showed the maximum value about 150 A/$\textrm{cm}^2$, while critical temperatures were around 90K and were independent of the grinding time.

• Child Health Nursing Research
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• v.13 no.1
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• pp.81-89
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• 2007

Purpose: This study was conducted to identify the degree of Internet addiction and factors influencing this addiction among high school students in Korea. Method: A total of 405 high school students in the Gyeoung-gi, Daegu and Gyeoung-buk areas were surveyed using questionnaires for data collection. Results: Internet addiction among high school students in Korea was relatively low. In the overall ratio distribution, however, the students who were classified as either addicted or at risk of addiction accounted for a high percentage of the students, 31.1%. Positive or negative relationships were found between internet addiction and the research variables but multiple regression analysis revealed that the most powerful predictor of Internet addiction was depression. Conclusion: Using the above results, it is necessary to develop Internet addiction prevention programs for adolescents. There should be a more comprehensive study in the future for an in-depth understanding of internet addiction of adolescents.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.73.1-73.1
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• 2013

It is believed that the current census of star clusters in the Milky Way is far from being complete, because of high extinction. Taking advantage of recent wide-field infrared surveys (the WISE as well as 2MASS, UKIDSS GPS, and VVV), we search for new star clusters in the central region of the Milky Way (720 $deg^2$-wide area at |1| < $30^{\circ}$ and |b| < $6^{\circ}$). We find 1840 candidates by visual inspection of the WISE images. The spatial distribution of these candidates show a strong concentration along the Milky Way, showing that most of them belong to the Milky Way. Among them, 26 are probably star clusters, considering their morphology, color-magnitude diagrams, and the degree of central concentration of stars. Eighteen of them appear to be very young in the embedded phase, and six of them are considered to be relatively old, showing a developed red giant branch. Implications of the primary results will be discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.5
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• pp.648-656
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• 2003

An experimental research was performed to study turbulent flow characteristic in a $90^{\circ}$ circular bend by using the PIV(Particle Image Velocimetry) method, this study found the time-mean velocity distribution, time-mean turbulent intensity with turbulent flow for Re = 10,000, 15,000, 20,000, and 25,000 along the test bend. It was found that the highest streamwise velocity of turbulent flow occurs near y/D = 0.5 and the flow moved to y/D =0.15. The peak turbulence intensity shifted toward the concave wall from $\theta= 45 and as \theta$ increased. the intensity decayed along the test tube.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1158-1161
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• 2004

Shell shaped hollow carbon nanoparticles are synthesized in the oxygen-hydrogen diffusion flame with $C_{2}H_{2}$ as precursor when it is irradiated with $CO_{2}$ laser of certain power. Below this power of laser, we couldn't get any other but amorphous soot. This shell shaped hollow carbon nanoparticles shows outer wall of high degree of crystallinity with void space inside of itself. And size distribution of these nanoparticles is measured with TEM image analysis. Also the structural comparison between this carbon nanoparticle and soot is done by Raman and XRD measurement. These results show this carbon nanoparticles are of grapheme structure, which means it has good crystallinity when compared with soot.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.57-66
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• 1985

This paper deals with an experimental study on a liquid atomization to investigate the break- up mechanism of a liquid film flow which is formed by a high speed air flow in parallel direction and an atomization characteristics of a liquid film flow in order to provide the basic data for the development of the twin fluid atomizer. Authors had built the simplified, transparent new devices which can form a uniform thickness of liquid film and an electrical measuring circuit of the liquid film thickness. By introducing the new devices and the measuring circuit, the time variation of a liquid film thickness the mean diameter of the droplets, the droplet size distribution, the degree of the dispersion and the atomization rate of a liquid film are measured experimentally. As the analysis of the study, it can be said the experimental investigation will fairly contribute for further study in this field of study.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2005.09a
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• pp.263-266
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• 2005

We made a stepping stone for asthma study by analyzing an asthma-specific protein-protein interaction network. It follows the power-law degree distribution and its hub nodes and skeleton frame of the network agreed with the prior knowledge about asthma pathway. This study is providing a systematic approach to analyze the complex effect of genes or to represent the frame of their relations associated with specific disease.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.588-590
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• 2008

The thermal signature of nucleation process is characterized by the induction time, the degree of supercooling, and the equilibrium temperature depression. The initiation of nucleation presents stochastic characteristics. The factors that affect nucleation are mechanical impact, ionic concentration, mineral surface characters, and pore size. Hydrate-bearing sediments behave mechanically like other cemented sediments. The data set has important implications for the calibration and interpretation of geophysical measurements and downhole logs collected in gas hydrate provinces, providing particular insight for the interpretation of P- and S-wave data and resistivity logs. In addition, laboratory formation history and ensuing pore-scale spatial distribution likely have a more pronounced effect on the macroscale mechanical properties of hydrate-bearing sediments

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1182-1189
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• 2010

The mechanical behavior of a granular material is governed by the applying effective stresses and its skeletal structure which is considered to be the packing of particles giving overall density and degree of anisotropic. Factors that affect soil packing are the particle size, size distribution and shape, and the arrangement of grain contact. Soil particle size and shape are the most important factor, but difficult to quantify. In this study, 2D Fourier analysis is applied to quantify the shape of granular particles. Jumunjin sand was used in the experiment and particle images are captured using an optical microscope. The results showed that three lower order Fourier descriptor are closely related with roundness, sphericity of the granular particle. Also statistical approach is used to determine roundness, form factor, elongation ratio, roughness of Jumunjin sand.

• Journal of Environmental Science International
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• v.5 no.3
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• pp.387-398
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• 1996

Granular sludge formation and it's activity change are the most important factors in achieving successful start-up and operation of UASB reactor. Nevertheless, the detailed mechanism is still unknown. On the basic of the experiments in laboratory-scale UASB reactor, the effect of hydrogen partial pressure on sludge granulation was evaluated. Size distribution method and specific metabolic activity of the sludge with the operation time were used as a means for estimating the degree of the sludge granulation. At the constant hydrogen loading, the granulation increased as starvation periods in hydrogen supply increased, resulting in high organic removal efficiency. It was evidient that hydrogen play very important role in granulation and sludge granulation was achieved through mutual symbiosis between hydrogen utilizing bacteria and hydrogen producing bacteria under the hydrogen dificient conditions. Key words : granular sludge, UASB reactor, hydrogen partial pressure.