• KSBB Journal
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• v.17 no.3
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• pp.295-301
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• 2002

The effects of nonionic surfactant (SPAN 20) on the desulfurization process by Rhodococcus sp. strain IGTS8 have been investigated at various oil/water ratios, pHs and concentrations of surfactant. The hexadecane containing DBT was employed as model oil. The presence of surfactant in the oil/water mixture stabilized the oil/water interface, thus enhanced the efficiency of desulfurization. The volume percentages of oil in the oil/water mixture were 30, 50 and 70%. The concentrations of surfactant were varied from 0 to 0.33 wt% relative to water phase. In general, the biodesulfurization efficiencies were decreased as the concentration of SPAN 20 and the volume percentage of oil phase increased.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.16-21
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• 2005

In paper, propose new partial resonance ZCS PWM controlled High frequency insulating Full-bridge DC/DC converter not using exciting current of high frequency transformer. It is compared with the existing principles in characteristics. It also realizes a widely stabilized ZVS operating using new ON-OFF control method at synchronized power rectification MOSFET of high frequency insulating transformer secondary. Besides, it is brought over 97[%] measurement efficiency by proposed DC-DC converts. It is proved effectiveness of new methods using DC UPS PWM rectifier as switching power supply.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.14-21
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• 2007

In order to enhance combustion efficiency, oxygen-enriched combustion is used by increasing the oxygen ratio in the oxidizer. However, since the flame temperature increases, NOx formation in the furnace seriously increases for low oxygen enrichment ratio. In this case, reburning is a useful technology for reducing nitric oxide. In this research, experimental studies have been conducted to evaluate the hybrid effects of reburning/selective non-catalytic reaction (SNCR) and reburning/air staging on NOx formation and also to examine heat transfer characteristics in various oxygen-enriched LPG flames. Experiments were performed in flames stabilized by a co-flow swirl burner, which were mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The paper reported data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. Overall temperature in the furnace, heat fluxes to the wall and NOx generation were observed to increase by low level oxygen-enriched combustion, but due to its hybrid effects of reburning, SNCR and Air staging, NOx concentration in the exhaust have decreased considerably.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.10
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• pp.367-376
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• 2018

University IT center usually has led IT system and headquarters have been working as a separate organization. If we apply the governance framework that is unique to the university system for IT governance in university IT project, IT transparency and efficiency are increased, and IT is no longer a simple tool but a university IT governance it will be stabilized. To improve existing problems, UCC was developed a unique framework of university organization based on CobiT Cube. So it can use effectively University IT on various side. I propose a method that can be applied to university information system sequentially through UCSP spiral process so that information service is classified into 5 areas and process is gradually applied.

• Journal of Hydrogen and New Energy
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• v.19 no.3
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• pp.217-225
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• 2008

A new micro reformer system consisted of a micro reformer, a microcombustor and a micro evaporator was studied experimentally and computationally. In order to satisfy the primary requirements for designing the microcombustor integrated with a micro evaporator, i.e. stable burning in a small confinement and maximum heat transfer through a wall, the present microcombustor is simply cylindrical to be easily fabricated but two-staged (expanding downstream) to feasibly control ignition and stable burning. Results show that the aspect ratio and wall thickness of the microcombustor substantially affect ignition and thermal characteristics. For the optimized design conditions, a premixed microflame was easily ignited in the expanded second stage combustor, moved into the smaller first stage combustor, and finally stabilized therein. A micro reformer system integrated with a modified microcombustor based on the optimized design condition was fabricated. For a typical operating condition, the designed micro reformer system produced 22.3 sccm hydrogen (3.61 W in LHV) in an overall efficiency of 12%.

• Journal of the Korean Ceramic Society
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• v.27 no.7
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• pp.934-942
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• 1990

The quarternary system ceramics 0.5[yPb(Zn1/3Nb2/3)O3-(1-y)Pb(Ni1/3Nb2/3)O3]-0.5[xPbTiO3-(1-x)PbZrO3](PZN-PNN-PT-PZ) was fabricated by the columbite precursor method to obtain a stabilized perovskite structure and by conventional method to evaluate the efficiency of the former methd. Dielectric and piezoelectric properties were investigated and the stability of the perovskite phase was studied as a function of PZN and PT contents and firing temperature. In the samples prepared by the columbite precursor method, the pyrochlore phase, which is detrimental to both the dielectric and piezoelectric properties, was not observed in the absence of PZN, and electric properties were improved even when fabricated at low temperature. By adding PZN, some pyrochlore phase appeared and the morphotropic phase boundary of the samples shifted to more Zr-rich composition. The temperature dependence of piezoelectric constant decreased with the addition of PZN, due to the rising of the Curie point.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.158-163
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• 2013

In this paper, thermal analysis of heatsink for 30 W class Chip-on-Board (COB) LED light source is performed by using SolidWorks Flow Simulation package. In order to increase the convection heat transfer, number of fin and shape of the heatsink is optimized. Furthermore, a copper spread is applied between the COB LED light source and the heatsink to mitigate the heat concentration on the heatsink. With the copper spread, the junction temperature between the COB LED light source and the heatsink is $50.9^{\circ}C$, which is $5.4^{\circ}C$ lower than the heatsink without the copper spread. Due to the improvement of the junction temperature, the light output is improved by 5.8% when the LED light source is stabilized. The temperature difference between the simulation and measured result of the heatsink with the copper spread is within $2^{\circ}C$, which verifies the validity of the thermal design method using a simulation package.

• Korean Journal of Poultry Science
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• v.22 no.2
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• pp.117-128
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• 1995

Vitarnin A levels of egg yolk from hens fed diets supplemented with vitamin A increased slowly up to Week 4, while the values rapidly increased thereafter. The highest value(360% of initial value) was observed at Week 8 in birds fed 64,000 IU of vitamin A/kg diet. On the other hand, the contents of vitamin E in egg yolk rapidly increased in the first 2 weeks of the experiment and then stabilized up to Week 8. However, the efficiency of egg transfer decreased(P<0.05) as dietary vitamins A and E levels increased. It took at least 4 weeks for the increased levels of vitamin A and E in eggs from hens fed diets supplemented with each vitamin to recover the normal levels. Vitamin E levels of egg yolk in hens fed the vitamin A supplemented diets decreased as dietary vitamin A level increased (P<0.05). On the other hand, a slightly reduced levels of vitamin A levels of egg yolks from hens fed the vitamin E supplemented diet for 4 weeks of experiment was recovered back to control level at Week 8(P<0.05). Supplemental vitamin A markedly decreased the yolk deposition of vitamin F when two vitamins were supplemented simultaneously. The yolk deposition of vitamin A decreased as high level of vitamin B was supplemented, suggesting an antagonistic interactions between the two vitamins.

• Carbon letters
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• v.6 no.3
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• pp.166-172
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• 2005

The objective of this study was to investigate the possibility of application for water treatment using the zeocarbon. The zeocarbon was mixture of zeolite and activated carbon. In general, the application of commercial zeocarbon to water treatment is difficult because of weak strength in water and the high pH value of effluents after water treatment. Therefore, we have modified the surface of zeocarbon. For the surface modification, we used the acid treatment to make surface functional group. As a result of modification, was created functional group on zeocarbon surface and was formed mesopore in zeocarbon. The surface modified zeocarbon was applied to removal of nitrogen. In removal experiments of nitrogen, removal efficiency was very high. And, strength of zeocarbon after water treatment and pH of effluents were stabilized. This indicates that the surface modified zeocarbon was easy to recover and reuse. Consequently, our results were shown the possibility of application for water treatment using the surface modified zeocarbon.

• KSBB Journal
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• v.29 no.4
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• pp.225-231
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• 2014

A microbial fuel cell (MFC) and bioelectrochemical systems are novel bioprocesses which employ exoelectrogenic biofilm on electrode as a biocatalyst for electricity generation and various useful chemical production. Previous reports show that electrogenic biofilms of MFCs are time varying systems and dynamically interactive with the electrically conductive media (carbon paper as terminal electron acceptor). It has been reported that maximum power point tracking (MPPT) method can automatically control load by algorithm so that increase power generation and columbic efficiency. In this study, we developed logic based control strategy for external load resistance by using $LabVIEW^{TM}$ which increases the power production with using flat-plate MFCs and MPPT circuit board. The flat-plate MFCs inoculated with anaerobic digester sludge were stabilized with fixed external resistance from $1000{\Omega}$ to $100{\Omega}$. Automatic load control with MPPT started load from $52{\Omega}$ during 120 hours of operation. MPPT control strategy increased approximately 2.7 times of power production and power density (1.95 mW and $13.02mW/m^3$) compared to the initial values before application of MPPT (0.72 mW and $4.79mW/m^3$).