• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.3
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• pp.198-204
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• 2022

In this paper, the 5kW and 50kW vertical axis wind turbines were studied using the ANSYS flow analysis simulation program. The 5 kW vertical shaft wind turbine has 30 units of the number of main blades and sub-blades and the electrical characteristics were analyzed by changing the tip speed ratio (TSR) from 0.2 to 06. A 50kW vertical axis wind turbine was designed based on the electrical characteristics of a 5kW vertical axis wind turbine. When the tip speed ratio was 0.5, the 5 kW wind power generation showed the maximum output of 9.5 kW and the efficiency of 0.28. The calculation of the power current(Ip) and the power voltage(Ep) show that, as the tip speed ratio increases, the power current(Ip) decreases and the power voltage(Ep) increases. And even if the tip speed ratio was changed, 5kW wind power generation was measured for output of 5 kW or higher. When the tip speed ratio was changed from 0.3 to 0.6, 50 kW wind power generation was output more than 50 kW. When the tip speed ratio of 50kW wind power generation was 0.4, the output was 58.37 [kW] and the efficiency was 0.318, and it was confirmed that the proposed 50kW wind power generation satisfies the design conditions.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.2
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• pp.45-57
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• 1998

The object of this experiment was to determine the optimum mixing ratio of paper mill sludge and sewage sludge with woodchips as a bulking agent. The bulking agent was mixed with the mixture of paper mill sludge and sewage sludge(2:1 by dried weight) at the rates of 0(W-0), 20(W-20), 33(W-33), and 50(W-50)% on volume basis, and then the mixtures were composted by forced aerated static pile. The changes of physicochemical properties of the mixtures were measured during the composting in order to evaluate the maturity of composts. The temperatures of W-30 and W-50 treatments increased rapidly as soon as the composting started, and reached $60^{\circ}C$ in the fifth day of composting. Reduction of hot water soluble C/N ratio of W-33 and W-50 treatments showed faster than that of W-0 and W-20 treatments at early stage of the composting. The contents of hot water soluble $NO_3{^-}-N$ showed little change in the early stage of the composting in all treatments, but increased rapidly after 20 days of the composting, and the contents of W-0 among all treatments were lower than the others. The G.I. values of W-50 treatment were over 80 before 20 days after starting the composting, those of W-0 treatment were over 80 after 30 days. As a result of evaluation of compost, W-33 and W-50 treatments were found very reasonable at the mixing ratio of a bulking agent. But it is very difficult to aerate compost pile for W-50 treatment than W-33 treatment due to intensified fluctuation of temperature. Considering cost, availability of a bulking agent, and productivity of compost, W-33 treatments more efficient than W-50 treatment.

• Korean Journal of Food Science and Technology
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• v.46 no.5
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• pp.581-587
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• 2014

The antioxidant and alcohol-degrading enzyme activities of soybean sprout sugar solutions (oligosaccharide and sucrose, $50^{\circ}Bx$) were characterized under different soaking conditions. The ratio of sugar solution to sprout content was 25%, 50%, and 75% (w/w), and the soaking times studied were 1, 3, 6, 12, and 24 h. Higher 1,1-diphenyl-2-pycrylhydrazyl (DPPH) radical-scavenging activity was detected in case of the oligosaccharide solution, compared to the sucrose solution. A similar tendency was observed for alcohol-degrading enzyme activity. When the ratio of sugar solution to sprout content was 50% (w/w), the total phenol and flavonoid contents were found to be higher, compared to those observed at 20% (w/w). However, we did not observe a significant difference between 50% and 75% (w/w). Soaking time did not significantly affect the antioxidant and alcohol-degrading enzyme activities of the solutions. As a result, when oligosaccharide solution was used for soaking soy sprouts at a ratio of >50% (w/w), higher antioxidant and alcoholdegrading enzyme activities were observed.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.445-450
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• 1975

These experiments were carried out to obtain useful yeast for Korean grape wine brewing. The 213 strains of yeasts were isolated from grapes sampled in Daejeon city and suburbs and then 3 strains among the isolated yeasts were selected as useful strains and identified. The results obtained as follows; 1. The 3 strains of W-49, W-50 and W-127 selected as useful yeasts were clarified to grape wine mash rapidly. 2. In the mashes clarified after storage of 45 days, the value of optical density of the case of W-50 strain was highest and the color was very thick, compared with the case of another strains. 3. In the pannel test of the grape wines, the case of W-49 and W-50 strains were best, the case of the W-127 strain and control yeast, Hb were similar each other as next order. 4. Among 3 strains selected as useful yeasts it were identified that the strains of W-49, W-50 selected as useful strains were Saccharomyces cerevisiae and the strain of W-127 was Saccharinyces pretoriencis by the Ladder manual. 5. All of these useful yeasts were appeared red color on TT C stain.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.285-291
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• 2005

Effects of the aqueous or 50% ethanolic extracts prepared by various extraction procedures on macrophage activation were determined by using the mouse macrophage cell line RAW264.7 cells as a indicator cell. The results demonstrated that the fractions prepared by aqueous extraction for 2 h and by microwave extraction with 50% ethanol at 60 W for 3 min had the greatest inducing abilities for NO production, and that the greatest ROS scavenging abilities were found in the fractions prepared by hot water extraction for 2 h or 3 h, by microwave extraction with 50% ethanol at 60 W for 3 min and by 0.5% HCl extraction, respectively. Phagocytotic activities against Candida albicans were found to be highest for the 50% ethanolic extracts prepared by microwave extraction for 3 min at 60 W, 80 W and 12 W, respectively. Especially, we found that a extract prepared by microwave extraction with 50% ethanol at 60 W for 3 min enables to induce effectively overall functional activation of macrophage, such as NO production, ROS scavenging and phagocytosis of C. albicans, respectively. These results demonstrated that a 50% ethanolic extraction using microwave at 60 W for 3 min would be useful for enrichment of macrophage-activating components contained in Hericium erinaceus, implying participation of protein-bound polysaccharides as a active factor.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.314-319
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• 2002

Performance analysis and test of a 50kW micro gas turbine is carried out. The present study was initiated in 1996 by KIMM researchers to develope a 50kW class turbogenerator gas turbine engine for hybrid vehicle propulsion system. but with its low emission and compactness, it seemed that it can also be applied as a source of distributed power generation. In this study, general description of the KIMM's efforts to acquire performance test skills of the self-made 50kW micro gas turbine engine. At present, non-load performance test up to 615000 rpm was accomplished and is expected to make through 80,000 rpm by the end of year. Several revisions in design and manufacture were made during the course of experiments. The resulting outputs is thought to be valuable for the further refinement of the system for eventual commercialization of the product.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.4
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• pp.440-446
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• 2011

In this paper, a X-band 50 W pulsed solid state power amplifier(SSPA) is designed and fabricated for radar systems. The SSPA consists of a driver amplifier, a high power amplifier, and a pulse modulator. The high power stage employes four 25 W GaAs FET to deliver 50 W at X-band. To meet the stringent target specification for the SSPA, we used a new hybrid pulse switching method, which combine the advantage of pulse modulation and bias switching method. The fabricated SSPA shows a power gain of 44.2 dB, an output power of 50 W over a 1.12 GHz bandwidth. Also, pulse droop < 1 dB meet the design goals and a rise/fall time is less than 12.45 ns. Fabricated X-band pulsed SSPA size is compact with overall size of $150{\times}105{\times}30\;mm^3$.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.249-251
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• 2009

In this paper, we present a study on the 50kW class power station development using lithium-polymer battery. The 50kW class power station purposes to compensate for peak load using 326[V] lithium-polymer battery bank. The output voltage is 380[V] in three-phase, peak load compensation is controlled based on load power. Finally, a 50kW power station system is built to verify the experiment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.76-79
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• 2016

This paper describes the successful development and the performance of X-band 50 W pulsed power amplifier using a 50 W GaN-on-SiC high electron mobility transistor. The GaN HEMT with a gate length of $0.25{\mu}m$ and a total gate width of 12 mm were fabricated. The X-band pulsed power amplifier exhibited an output power of 50 W with a power gain of 6 dB in a frequency range of 9.2~9.5 GHz. It also shows a maximum output power density of 4.16 W/mm. This 50 W GaN HEMT and X-band 50 W pulsed power amplifier are suitable for the radar systems and related applications in X-band.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.31-33
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• 1999

In this paper, a operating characteristics of the 50 kW grid-connected Photovoltaic(PV) Power system which is by means of initial PV datum analyzing is reported. The development of a 50 kW class photovoltaic power generation system including a DC/AC inverter is suggested to investigate the system performance for grid connection. The results of the demonstration test of a 50 kW class grid-connected PV system show that the system utilization rate is 15.6% and the inverter efficiency is 94% at 80% load.