• Korean Journal of Computational Design and Engineering
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• v.17 no.5
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• pp.312-323
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• 2012

Planetary gearing is a gear system consisting of one or more planet gears, revolving about a sun gear. While the planetary gear system has many advantages- for example, high power density, large reduction in a small volume, multiple kinematic combinations, pure torsional reactions, and coaxial shafting, it has not been widely used because of its high bearing loads, inaccessibility, and design complexity. It is also necessary to shift several pairs of gear profiles at a same time. Therefore, designing profile shifted planetary gear system is a difficult and know-how dependent job. This study provides a practical solution to design a profile shifted gear system by the procedural design scheme, and proposes a bearing integrated structure of the dual stage profile shifted gear system with a robust output end. A dual stage profile shifted gear system with the bearing integrated structure is manufactured by the proposed design scheme in this study. This gear system is verified that it is good enough to commercialize, because it has high performance with high gear ratio and robust output end against axial and radial directional runouts in a small space.

• Korean Journal of Food Science and Technology
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• v.35 no.1
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• pp.72-76
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• 2003

Ultrafiltration (UF) tests performed on traditional soy sauce (kanjang) using UF flat membrane test cell unit with thin film laminar flow similar to the spiral type membrane module in batch operations revealed reduction in permeate flux is proportional to the logarithm values of volume reduction ratio of the retentate kanjang at different feed rate of kanjang. Feed rate of 1.5 L/min was found to be adequate for long-term UF operation of kanjang using the test unit attached with MW cut-off size of 200,000 dalton polyoleffin plastic membrane in batch operation with the least concentration polarization. The higher the feed rate of kanjang, the lower the permeability of total nitrogen and NaCl, resulting in lower optical density at 500 nm and lower permeability of minerals such as Cu, Mn, and Mg. Microbial cells were completely rejected regardless of the feed rate, whereas most free amino acids were not.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.417-420
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• 2008

In this study, the characteristics of strength development and hydration heat on high volume fly ash concrete(HVFAC) was experimentally investigated. Two levels of W/B were selected. Seven levels of fly ash replacement ratios and two levels of silica fume replacement ratios were adopted. In the concrete mix, the water content of $125kg/m^3$ was used, which is less than that of usual water content. As a result, it appeared that the compressive strength gradually decreased with increasing fly ash replacement ratio at the early age, but the difference of strength up to replacement ratio of 50% was little at the age of 91 days because of the pozzolanic reaction of fly ash. The effect of hydration heat reduction on the concrete was affected by the fly ash replacement ratio. When the replacement ratio was over 30%, the reduction efficiency of hydration heat was large.

• Korean Journal of Agricultural Science
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• v.37 no.3
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• pp.501-508
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• 2010

A swirl chamber type diesel engine attachable to 18 kW agricultural tractors was improved to reduce exhaust emissions. Compression ratio and throat area ratio of the combustion chamber were varied to determine optimum combustion conditions. Tests were composed of full load and 8-mode emission tests. Compression ratio was fixed as 21, but the swirl chamber volume was increased by 3.8%. Output power, torque, specific fuel consumption, exhaust gas temperature, and smoke level were not considerably different for compression ratios of 21.5 (reference condition) and 21 (test condition), while NOx, HC, CO and PM levels for the compression ratio of 21 were decreased by 11%, 46%, 28%, 11%, respectively, from those for the compression ratio of 21.5. The tests were also conducted with a compression ratio of 22 and 4.3% increased chamber volume. Output power, torque, exhaust gas temperature and smoke level were greater, while specific fuel consumption was less for the compression ratio of 22 than those for the compression ratio of 21.5. Increase of compression ratio decreased HC and CO levels by 24%, 39%, but increased NOx and PM levels by 24%, 39%. Based on these results, a compression ratio of 21 was selected as an optimum value. Then, full load tests with the selected compression ratio of 21 were carried out for different throat ratios of 1.0%, 1.1%, 1.2%. Output power and torque were greatest and smoke was lowest when throat area ratio was 1.1%, which satisfied the target values of specific fuel consumption (less than 272 g/$kW{\cdot}h$) and exhaust gas temperature (less than $550^{\circ}C$). Therefore, a throat area ratio of 1.1% was selected as an optimum value.

• Journal of the Mineralogical Society of Korea
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• v.27 no.4
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• pp.311-320
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• 2014

A magnetic separation study was conducted for a soil sampled from a landfill site where steel slag had been dumped for a long time. Heavy metal concentrating effect was evaluated by analyzing heavy metal content of magnetically separated soil and passed through soil. The effect was compared between soil after soil-washing process and original landfill soil and the effect was also tested between wet condition-magnetic separation and dry condition-magnetic separation. Separated ratio was relatively higher in non-soil washed sample. The water content has no significant effect on the separation rate. The concentrating effect of Fe, Pb, Cu, and Cd were 3.2, 2.1, 12.1, 2.5, 1.5 and 17.4, 7.0, 15.7, 9.6, 7.0 respectively for non-soil washed sample and soil washed sample. We can expect a bigger volume reduction effect from soil-washed samples. The volume reduction effect was obtained from the separation in dry condition. However, when the separation ratio is too high the volume reduction effect decreases. The magnetic separation leads to a volume reduction and concentration of heavy metals into a portion of soil in case of paramagnetic particles contained soil.

• Journal of Information Display
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• v.12 no.2
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• pp.77-83
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• 2011

The memory compression algorithm CCC-LCP (color-count-controlled local color palette) reduces flicker in the liquid crystal display (LCD) overdrive. Its compression ratio is 1:5.4 for 10-bit images, with a 33 dB PSNR peak signal-to-noise ratio and with five times flicker reduction compared with the block truncation coding. The authors' two-alternative forced choice subjective tests proposed two new soundness properties, the 'CMP harmlessness' and 'OD non-lost (or OD liveliness)', to clarify the functional interaction between the overdrive functionality OD and the compression functionality CMP. The tests verified that CCC-LCP is practically applicable (at a 1.2H viewing distance threshold) for 42" 37-ppi WXGA TVs.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2090-2091
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• 2007

We investigated the characteristics of transformer type SFCL with neutral line. The transformer type SFCL having neutral line has achieved the simultaneous quench because the secondary winding has acted as parallel reactor. The fault current of SFCL was limited according to ratio of turn number between primary and secondary windings. Therefore, the power burden of superconducting element can be reduced by reduction of ratio of turn number between primary and secondary windings. As a result, we could expect reduction of it's volume in the transformer type SFCL.

• Bulletin of the Korean Chemical Society
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• v.8 no.2
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• pp.79-83
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• 1987

The reduction of a series of 1-substituted benzyl-3-cyanoquinolinium ions (p-$cH_3$, H, p-Br, m-F, p-CN) by sodium borohydride has been investigated. In all cases the products from these reactions were found to be 1, 2-dihydroquinolines over 82% yields. Rates of reduction were measured in basic condition and in solvent system consisting of 4 parts of isopropyl alcohol and 1 part of water by volume. Second order rate constants were obtained for these reactions. When the ratio of [$OH^-$] to [$BH_4^-$] becomes large the observed rate constants ($K_{obs}$) decrease by a small factor. Reaction scheme and rate law are discussed. Bronsted ${\alpha}(=\frac{d\;In\;k}{d\;In\;K})$ obtained by using the value of equilibrium constant K, which was obtained previously, was not 0. Instead, a value of 0.36 was obtained which indicated that the reduction by borohydride was structure-dependent according to the Marcus formalism even though the reaction rate was close to the diffusion limit.

• The Journal of Internal Korean Medicine
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• v.21 no.4
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• pp.605-613
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• 2000

Objective : The investigation had been performed since from January 1st to August 31th of 1998. The patients for the experiment were mainly composed of patients who had trouble in breathing due to the pneumonectasis, asthmas, pneumonias. The percent of men is 67% in sex distribution and the ratio of persons over 50's was 85%, The effect was invastgated for the labored respiration who had Keumsuyukunjeon. Methods : In this research, some remarkable results are referred which were detected by measuring the variations of the breathing volume of 20 patients after taking Keumsuyukunjeon. Picrometer is used for the measurement of the volume. Results : From the relations between the breathing volume before treatment and the enhancement ratio, the increase of the enhancement ratio and the better response to the medicine were shown to the more serious patients. The period of treatment was 27.5 days average. The enhancement ratio of smoker was 23, and that of non-smoker was 50. At the test of relation between the trouble rate in breathing and the enhancement ratio, Grade ill shows the highest enhancement value 50%. conclusions : It is found that Keumsuyukunjeon gives a noticeable benefit for the patients whose main symptom was breathing problem. Long-term treatments for the serious and aged patients will make much more efficient to the reduction of the symptoms.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.164-173
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• 2011

In the present study, the stability of a compressed air energy storage cavern was numerically assessed by concrete plug shapes in order to investigate the optimal shape of concrete plug. The concrete plugs were cylindrical, embedded cylindrical, tapered, and wedged in shape. The stability assessment was carried out based on factor of safety through a strength reduction method and a volume ratio which refers to the ratio of the volume of yield regions in concrete induced by internal pressure to all concrete volume. The results from the present study indicated that the embedded cylindrical and taper shaped plugs were mechanically more stable than the cylindrical and wedge shaped plugs. However, from a comparison of stress distributions in rock mass between the embedded cylindrical and taper shaped plugs, the taper shaped plug was found to be more optimal than the embedded cylindrical plug, since the embedded cylindrical plug caused more stress concentration in the interface between the plug and rock mass than the taper shaped plug.