• The KSFM Journal of Fluid Machinery
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• v.11 no.1
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• pp.33-39
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• 2008

Hybrid power generation systems combining a solid oxide fuel cell and a gas turbine is promising due to their high efficiency. In the pressurized hybrid system, the operating condition of the gas turbine may play a critical role in designing the hybrid system. In particular, prevention of surge of the compressor can be a critical issue. The existence of fuel cell between the compressor and the turbine may cause an additional pressure loss and thus compressor operating points tend to approach the surge if the original turbine inlet temperature is pursued. In this study, bypassing some of the turbine inlet gas directly to the turbine exit side is simulated. Its effects on suppressing the surge problem and change in performance characteristics are discussed.

• Journal of Hydrogen and New Energy
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• v.22 no.1
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• pp.51-59
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• 2011

Sulfur-Iodine (SI) cycle, which thermochemically splits water to hydrogen and oxygen through three stages of Bunsen reaction, HI decomposition, and $H_2SO_4$ decomposition, seems a promising process to produce hydrogen massively. Among them, the decomposition of $H_2SO_4$ ($H_2SO_4=H_2O+SO_2+1/2O_2$) requires high temperature heat over $800^{\circ}C$ such as the heat from concentrated solar energy or a very high temperature gas-cooled nuclear reactor. Because of harsh reaction conditions of high temperature and pressure with extremely corrosive reactants and products, there have been scarce and limited number of data reported on the pressurized $H_2SO_4$ decomposition. This work focuses whether the $H_2SO_4$ decomposition can occur at high pressure in a noble-metal reactor, which possibly resists corrosive acidic chemicals and possesses catalytic activity for the reaction. Decomposition reactions were conducted in a Pt-lined tubular reactor without any other catalytic species at conditions of $800^{\circ}C$ to $900^{\circ}C$ and 0 bar (ambient pressure) to 10 bar with 95 wt% $H_2SO_4$. The Pt-lined reactor was found to endure the corrosive pressurized condition, and its inner surface successfully carried out a catalytic role in decomposing $H_2SO_4$ to $SO_2$ and $O_2$. This preliminary result has proposed the availability of noble metal-lined reactors for the high temperature, high pressure sulfuric acid decomposition.

• The Journal of Korean Medicine
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• v.34 no.4
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• pp.12-20
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• 2013

Objectives: This study compared Gumiganghwal-tang (GGT) decoctions produced using different pressure levels for various extraction times to determine the optimal extraction conditions through hydrogen ion concentration (pH), total soluble solids content (TSSC), extraction yield, and content of chemical compounds. Methods: Decoctions were prepared by the pressure levels of 0 or $1kgf/cm^2$ for 30-180 min. The pH and TSSC were measured, the extraction yield was calculated, and the amounts of the chemical compounds were determined using high performance liquid chromatography. Results: The higher pressure and longer extraction time decreased the pH value, while those conditions increased TSSC and extraction yield: the decoction produced in 180 min by pressurized method showed the minimum value of pH, but maximum values of TSSC and extraction yield. The chemical compounds showed higher amounts in decoctions produced by non-pressurized methods than pressurized methods and their amounts were decreased over the peak extraction time in both pressurized and non-pressurized methods. The results of regression analysis confirmed the correlative influences of the pressure and extraction time on pH, TSSC, and extraction yield. Conclusions: This study suggests that pressure and extraction time influence the compositional constituents in GGT decoctions, and the non-pressurized method for 120 min should be chosen as the optimal extraction condition for the preparation of GGT decoction.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.546-552
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• 2009

Enzymatic ethanolysis of wheat germ oil with immobilized lipase was investigated for enhancing the function of wheat germ oil. Ethanolysis reactions were carried out in two different systems; non-pressurized and pressurized system. In non-pressurized system, the enzymatic ethanolysis was carried out in an erlenmeyer flask(25 ml) containing a mixture of wheat germ oil and 99.90% ethanol using 1~5 wt% immobilized lipase as Lipozyme TL-IM and Lipozyme RM-IM and the reaction mixtures were incubated at $40{\sim}70^{\circ}C$ with 120 rpm shaking. In pressurized system, the enzymatic ethanolysis was carried out at various condition; immobilized lipase concentration(2 wt%), reaction time(24 h), reaction temperature($40{\sim}60^{\circ}C$) and reaction pressure(75, 100, 150, 200 bars). The samples obtained from each fraction were analyzed by HPLC for analysing contents of monoglyceride, diglyceride, and triglyceride. The conversion of wheat germ oil relied on the reaction temperature and the concentration of immobilized lipase. The optimum condition of enzymatic ethanolysis in non-pressurized and pressurized systems was at $50^{\circ}C$ and 100 bar.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.3
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• pp.201-207
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• 2000

In this study, methodologies for checking the interference between in-core instrumentation (ICI) guide tubes for routing of ICI guide tubes in the reactor coolant system of typical Pressurized Water Reactor under cold and normal operation (NOP) conditions are presented. The closest points of ICI guide tubes under cold condition are calculated by using minimize technique and are used as data for NOP analysis. Movements of ICI guide tubes under NOP condition are performed by the commercial computer code, SUPERPIPE.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.5-9
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• 2013

Electrokinetics technology is proposed for improving the recovery metals ion and oil from clay-sandy soil. In order to restore or extract them from clay-sandy soil, the gas produced by anode chamber is re-injected to the clay-sandy soil(sample). Samples produced in this study were completed to verify the proposed performance for 7 days by gradually increasing the pressure to the final pressure of 30psi($2.11kgf/cm^2$) through the compression process. Before compression, the copper rings were inserted into the sample, allowing us to observe the changes in appearance of copper ring after the end of the experiment. In this study, pressurized module and non-pressurized module were tested, respectively. The condition of test is a continuous process and the voltage gradient is 2V/cm during 24 hours. As a result, the efficiency of pressurized module is better than non-pressurized module.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.49-63
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• 2008

The objectives of this research were to evaluate the pressurized/the main inlet water flowrate ratio which have been used as the most important parameter for operating the pump diffusion mixer until now, to suggest the alternative operating parameter and the relating criteria if the flowrate ratio was not inadequate. For the objectives of this research, computational fluid dynamics (CFD) simulation was conducted for 21 cases of flowrate ratio in full-scaled pump diffusion mixer. From the results of CFD simulation, the local velocity gradient values were calculated in each case in order to analyze the simulation results in more detail. For verifying CFD simulation, wet test was conducted. The wet test was to measure the factual coagulant dispersion distribution at a distance of 5.4m from deflector. From both results of CFD simulation and wet test, flowrate ratio was inadequate as operating parameter or criteria, on the other hand the pressurized/the main inlet velocity ratio(dimensionless) was useful in predicting the performance of pump diffusion mixer. Also, the injected coagulant could be dispersed evenly in overall cross section on the condition that pressurized/the main inlet velocity ratio(dimensionless) is over at least 20.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.791-793
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• 2009

Hydrogen has been recognized of the energy source for the future, in terms of the most environmentally acceptable energy source. A pressurized fluidized bed reactor made of carbon steel with 0.076 m I.D. and 1.0 m in height was employed for the thermocatalytic decomposition of methane to produce amount of $CO_2$ - free hydrogen with validity from a commercial point of view. The fluidized bed was proposed for withdrawing of product carbons from the reactor continuously. The methane decomposition rate with the carbon black N330 catalyst was rapidly reached a quasi-steady state and remained for several hour. The methane thermocatalytic decomposition reaction was carried out at the temperature range of 850 - 950 $^{\circ}C$, methane gas velocity of 2.0 $U_{mf}$ and the operating pressure of 1.0 -3.0 bar. Effect of operating parameters such as reaction temperature, pressure on the reaction rates was investigated and predicted the effect of a change in conditions on a chemical equilibrium thermodynamically, according to Le Chatelier's principle.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.286-291
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• 2000

The reactor pressure vessel is usually cladded with stainless steel to prevent corrosion and radiation embrittlement, and number of subclad cracks have been found during an in-service-inspection. Therefore assessment for subclad cracks should be made for normal operating conditions and faulted conditions such as PTS. Thus, in order to find the optimum fracture assessment procedures for subclad cracks under a pressurized thermal shock condition, in this paper, three different analyses were performed, ASME Sec. XI code analysis, an LEFM(Liner elastic fracture mechanics) analysis and an EPFM(Elastic plastic fracture mechanics) analysis. The stress intensity factor and the Maximum $RT_{NDT}$ were used for characterizing. Analysis based on ASME Sec. XI code does not completely consider the actual stress distribution of the crack surface, so the resulting Maximum allowable $RT_{NDTS}$ can be non-conservative, especially for deep cracks. LEFM analysis, which does not consider elastic-plastic behavior of the clad material, is much more non-conservative than EPFM analysis. Therefore, It is necessary to perform EPFM analysis for the assessment of subclad cracks under PTS.

• Journal of Hydrogen and New Energy
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• v.27 no.5
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• pp.589-596
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• 2016

Effects of pressure, temperature, gas velocity, and fuel flow rate on reduction of three oxygen carriers, SDN70, OC-1, OC-2, were measured and investigated in a pressurized bubbling fluidized bed reactor. Among three oxygen carriers OC-2 was selected as the best oxygen carrier in view of fuel conversion and $CO_2$ selectivity. However, all oxygen carriers showed good reactivity even at high pressure conditions. SDN70 particle showed maximum reactivity at $900^{\circ}C$ and low reactivity at $950^{\circ}C$. However, reactivity decay of OC-1 and OC-2 particles at high temperature condition was negligible. The fuel conversion and the $CO_2$ selectivity slightly decreased as the gas velocity increased, whereas they are slightly increased as the fuel concentration increased.