• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.9
• /
• pp.781-787
• /
• 2014

A pressurized wire mesh heating reactor (PWMR) can provide high pressure and temperature experimental conditions up to 50 atm and 1750 K, respectively. This equipment was developed to evaluate the intrinsic reaction kinetics of $CO_2$ gasification. A PWMR utilizes a platinum (Pt) wire mesh resistance to generate heat with a direct current (DC) electricity supply. This DC power supply can then be controlled by computer software to reach the exact expected terminal temperature and heating period. In this study, BERAU (sub-bituminous Indonesian coal) was pulverized then converted into char with a particle size of $90-150{\mu}m$. This was used in experiments with various pressures (1-40 atm) and temperatures (1373-1673 K) under atmospheric conditions. The internal and external effectiveness factor was analyzed to determine the effects of high pressure. The intrinsic reaction kinetics of BERAU char was obtained using $n^{th}$ order reaction rate equations. The value was determined to be 203.8kJ/mol.

• Korean Chemical Engineering Research
• /
• v.52 no.3
• /
• pp.347-354
• /
• 2014

Economic evaluation of the manufacturing technology of high-value chemicals through the carbonation reaction of carbon dioxide contained in the flue gas was performed, and analysis of the IRR (Internal Rate of Return) and whole profit along the production plan of the final product was conducted. Through a carbonation reaction with sodium hydroxide that is generated from electrolysis and by using carbon dioxide in the combustion gas that is generated in the power plant, it is possible to get a high value products such as sodium bicarbonate compound and also to reduce the carbon dioxide emission simultaneously. The IRR (Internal Rate of Return) and NPV (Net Present Value) methods were used for the economic evaluation of the process which could handle carbon dioxide of 100 tons per day in the period of the 20 years of plant operation. The results of economic evaluation showed that the IRR of baseline case of technology was 67.2% and the profit that obtained during the whole operation period (20 years) was 346,922 million won based on NPV value. When considering ETS due to the emissions trading enforcement that will be activated in 2015, the NPV was improved to a 6,000 million won. Based on this results, it could be concluded that this $CO_2$ carbonation technology is an cost-effective technology option for the reduction of greenhouse gas.

• Applied Chemistry for Engineering
• /
• v.31 no.3
• /
• pp.323-327
• /
• 2020

The reaction characteristics of Ni/CeO_2-X which is highly efficient at a low temperature was investigated for an application to carbon dioxide methanation process. The CeO_2-X support was obtained by the heat treatment of Ce(NO₃)₃ at 400 ℃ and the catalyst was prepared by impregnation process. The operating parameters of the experiment were the internal pressure of the reactor, the composition of oxygen, methane, and hydrogen sulfide in the inlet gas and the reaction temperature. When Ni/CeO_2-X was used for the carbon dioxide methanation reaction, the CO₂ conversion rate increased by more than 25% as the pressure increased from 1 to 3 bar. The increase was large at a low reaction temperature. When both oxygen and methane were in the inlet gas, the CO₂ conversion rate of the catalyst decreased by up to 16 and 4%, respectively. As the concentration of oxygen and methane increased, the reduction rate of the CO₂ conversion rate tended to increase. In addition, the hydrogen sulfide in the inlet gas reduced the CO₂ conversion rate by up to 7% and caused catalyst deactivation. The results of this study will be useful as basic data for the carbon dioxide methanation process.

• Journal of Hydrogen and New Energy
• /
• v.33 no.6
• /
• pp.723-732
• /
• 2022

Cracking ammonia inside solid oxide fuel cell (SOFC) stack is a compact and simple way. To prevent sharp temperature fluctuation and increase cell efficiency, the decomposition reaction should be spread on whole cell area. This leading to a question that, how does anode thickness affect the conversion rate of ammonia and the cell voltage? Since the 0D model of SOFC is useful for system level simulation, how accurate is it to use equilibrium solver for internal ammonia cracking reaction? The 1D model of ammonia fed SOFC was used to simulate the diffusion and reaction of ammonia inside the anode electrode, then the partial pressure of hydrogen and steam at triple phase boundary was used for cell voltage calculation. The result shows that, the ammonia conversion rate increases and reaches saturated value as anode thickness increase, and the saturated thickness is bigger for lower operating temperature. The similar cell voltage between 1D and 0D models can be reached with NH₃ conversion rate above 90%. The 0D model and 1D model of SOFC showed similar conversion rate at temperature over 750℃.

• Journal of Yeungnam Medical Science
• /
• v.5 no.2
• /
• pp.47-52
• /
• 1988

The intradermal(ID) test has been widely used in Korea and several reports about the results of the ID test are known. We examined the egg of Clonorchis sinensis(C. s.) by ID test in 443, stool's egg-counting technique in 79 and direct smear(cellophane thick smear technique) in 1304 subjects. The results are as follows.: 1. The positive rate of C. s. was 3.8% out of 1304 persons. 2. The sensitivity of ID test was 82.1% out of 39 persons and, the specificity was 64.6% out of 404 persons. 3. The false positive of ID test 35.4% out of 404 persons and, the false negative was 17.9% out of 39 persons. Intradermal test is a rapid, sensitive and useful supplementary diagnostic tool for the detection of Clonorchiasis infection and must be used as screening test with direct smear of stool but cross reaction with other helminth infections and moderate false reaction are the main disadvantages in its practical application.

• Korean Chemical Engineering Research
• /
• v.47 no.6
• /
• pp.727-733
• /
• 2009

Effects of $Ca(OH)_2$ concentration(0.16~0.64 wt%), total volumetric flow rate(3~6 L/min) and $CO_2$ volume fraction(0.3~0.6) on morphology of the precipitated $CaCO_3$ and the mean particle size of the precipitated $CaCO_3$ were investigated in the slurry bubble column reactor. Experiments were carried out in acrylic reactor($0.11m-ID{\times}1.0m-high$) with a internal tube($0.04m-ID{\times}1.0m-high$). The calibration curve on the mass ratio of $CaCO_3$ to $Ca(OH)_2$ was obtained by FT-IR for the conversion of $Ca(OH)_2$ with the reaction time. The reaction rate of $Ca(OH)_2$ increased with increasing the volumetric flow rate of $CO_2$. From SEM images, the crystal size of $CaCO_3$ increased with increasing the reaction rate in the saturated concentration of $Ca(OH)_2$ (0.16 wt%). In addition, the crystal size of precipitated $CaCO_3$ decreased with increasing the concentration of $Ca(OH)_2$, but the mean particle size of precipitated $CaCO_3$ increased with increasing the concentration of $Ca(OH)_2$.

• The Journal of Internal Korean Medicine
• /
• v.11 no.2
• /
• pp.22-42
• /
• 1990

Sabaiksan has been prescribed to treat various allergic diseases in herbal medicine which were induced by various vasoactive amine released from the mast cells. The constituents of Sabaiksan are Mori Cortex Radices(MCR), Lycii Cortex Radicis(LCR) and Glycyrrhizae Radix(GR). Recently, simple models of compound 48/80 induced anaphylactic shock and cutaneous reaction in vivo were developed to test various agents employed in the field of allergy and toxicology research. The purpose of this study is to evaluate the effects of Sabaiksan on compound 48/80 induced anaphylactic stock, cutaneous reaction and mesenteric mast cell degranulation rate in ICR mice, and on compound 48/80 induced peritoneal mast cell degranulation and histamine release in vitro. Groups of ICR mice were intraperitoneally pretreated with $100{\mu}{\ell}$ of saline, $MCR(2g/m{\ell}),\;LCR(2g/m{\ell}),\;GR(g/m{\ell})$ or Sabaiksan itself(MCR+LCR+GR) at 24, 12 and 1 hour before compound 48/80 solution ($10{\mu}{\ell}/gm$ B. W) were peritoneally given into them, and then mortality within 72 hours after the compound 48/80 injection, and mesenteric mast cell degranulation rate at 15 minutes after compound 48/80 injection were calculated. In vitro experiment, $400{\mu}{\ell}$ of rat peritoneal mast cell suspension$(10^6cell/m{\ell})$ were pretreated with $50{\mu}{\ell}$ of saline, $MCR(2g/m{\ell}),\;LCR(2g/m{\ell}),\;GR(g/m{\ell})$ or Sabaiksan itself at room temperature for 30 minutes, and then $50{\mu}{\ell}$ of compound 48/80 solution $(100{\mu}g/m{\ell})$ were added into it. 30 minutes after the addition of compound 48/80 solution, histamine release assay in the supernatant of peritoneal mast cell suspension were performed employing radioisotope enzymatic assay and morphologic changes of mast cells in each regular time point were photographed. Compared with controls, compound 48/80 induced anaphylactic shock was significantly inhibited by MCR and GR pretreatment into the ICR mice. Significant inhibition of compound 48/80 induced cutaneous reaction, mesenteric mast cell degranulation rate in vivo and histamine release from the rat peritoneal mast cells in vitro was observed only in MCR pretreated group. From the above results, it is suggested that MCR component of Sabaiksan may playa key role to suppress mast cell function since it has been applied to various allergic diseases.

• Applied Chemistry for Engineering
• /
• v.10 no.5
• /
• pp.701-706
• /
• 1999

The effect of siloxane oligomer content on thermal stability and internal stress of DGEBA epoxy resin was investigated. Siloxane-epoxy polymers having terminal epoxy group were prepared by reaction of siloxane-DDM prepolymer with DGEBA epoxy resin. Thermal stability was studied in terms of the initial decomposition temperature(IDT), temperature of maximum rate of weight loss($T_{max}$), integral procedural decomposition temperature(IPDT), and decomposition activation energy($E_t$) using TGA data. The thermal stability increased with increasing the siloxane oligomer content and showed a maximum value in the case of 5 wt% siloxane oligomer content in the blend system. While, the coefficient of thermal expansion(${\alpha}_r$) and the flexural modulus($E_r$) allowed us to study internal stress of the blend system. As the content of siloxane oligomer increases, the internal stress systematically decreases as decreasing both ${\alpha}_r$ and $E_r$.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.12
• /
• pp.1257-1263
• /
• 2011

This paper is dedicated to the study on the external and internal mass transfers of glucose for succinic acid fermentation under substrate and product inhibitions using a bioreactor with stirred bed of immobilized Actinobacillus succinogenes cells. By means of the substrate mass balance for a single particle of biocatalysts, considering the kinetic model adapted for both inhibitory effects, specific mathematical models were developed for describing the profiles of the substrate concentration in the outer and inner regions of biocatalysts and for estimating the substrate mass flows in the liquid boundary layer surrounding the particle and inside the particle. The values of the mass flows were significantly influenced by the internal diffusion velocity and rate of the biochemical reaction of substrate consumption. These cumulated influences led to the appearance of a biological inactive region near the particle center, its magnitude varying from 0 to 5.3% of the overall volume of particles.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.2
• /
• pp.150-156
• /
• 2022

This study proposes a design method of fuel cell DC/DC converter using in 5-ton forklift. For efficient hydrogen usage, targeted fuel cell system recirculates discarded hydrogen after fuel cell reaction. Recirculating hydrogen contains much impurities that reduces output power, increasing pressure that can damage the internal fuel cell reaction system. The proposed DC/DC converter effectively converts fuel cell power considering the voltage drop rate to reflect the recirculating hydrogen. Then, frequency control method is used to regulate the current ripple amount for battery and fuel cell hybrid configuration. Proposed power converter system design and control methods are verified in a practical fuel cell system that implements recirculating hydrogen.