• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.9-16
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• 2022

Syngas, also known as synthesis gas, synthetic gas, or producer gas, is a combustible gas mixture generated when organic material (biomass) is heated in a gasifier with a limited airflow at a high temperature and elevated pressure. The present research was aimed at modifying the existing LPG engine generator for fully operated syngas. During this study, the designed gasifier-powered woodchip biomass was used for syngas production to generate power. A 6.0 kW LPG engine generator was modified and tested for operation on syngas. In the experiments, syngas and LPG fuels were tested as test fuels. For syngas production, 3 kg of dry woodchips were fed and burnt into the designed downdraft gasifier. The gasifier was connected to a blower coupled with a slider to help the air supply and control the ignition. The convection cooling system was connected to the syngas flow pipe for cooling the hot produce gas and filtering the impurities. For engine modification, a customized T-shaped flexible air/fuel mixture control device was designed for adjusting the correct stoichiometric air-fuel ratio ranging between 1:1.1 and 1.3 to match the combustion needs of the engine. The composition of produced syngas was analyzed using a gas analyzer and its composition was; 13~15 %, 10.2~13 %, 4.1~4.5 %, and 11.9~14.6 % for CO, H₂, CH₄, and CO₂ respectively with a heating value range of 4.12~5.01 MJ/Nm³. The maximum peak power output generated from syngas and LPG was recorded using a clamp-on power meter and found to be 3,689 watts and 5,001 watts, respectively. The results found from the experiment show that the LPG engine generator operated on syngas can be adopted with a de-ration rate of 73.78 % compared to its regular operating fuel.

• Journal of Hydrogen and New Energy
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• v.34 no.3
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• pp.316-326
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• 2023

Development of carbon-neutral fuel production technologies to solve climate change issues is progressing worldwide. Among them, methane can be produced through the synthesis of hydrogen produced by renewable energy and carbon dioxide captured through a CO₂ methanation reaction, and the fuel produced in this way is called synthetic methane or e-methane. The CO₂ methanation reaction can be conducted via biological or thermochemical methods. In this study, a 30 Nm³/h thermochemical CO₂ methanation process consisting of an isothermal reactor and an adiabatic reactor was used. The CO₂ conversion rate and methane concentration according to the temperature measurement results at the center and outside of the adiabatic reactor were analyzed. The gas flow into the adiabatic reactor was found to reach equilibrium after about 1.10 seconds or more by evaluating the residence time. Furthermore, experimental and analysis results were compared to evaluate performance of the reactor.

• Journal of Mushroom
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• v.2 no.2
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• pp.88-96
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• 2004

This study was executed to decide the physiological characteristics of Ferule mushroom. Four strains of Ferule mushroom were tested to select a superior strain in its mycelial growth. The pertinent substrates, temperature and pH ranges for the growth of selected strain were determined. And then, the wood rotting ability and type of the Ferule mushroom were determined. The superior strain F-2 among four strains was selected, on the basis of its vegetative mycelial growth and density on agar media. Mycelial growth of F-2 was the best on MYPA among other tested synthetic or semi-synthetic media. The temperature range for pertinent mycelial growth was about $25{\sim}34^{\circ}C$ and best at $30^{\circ}C$. The optimum pH range on MYPA was 5.0~6.0. The mycelial growth was mostly stimulated by soluble starch at cont. 1% (w/w) and secondly, maltose among several carabon sources and by mixed solution of YE(0.25%) and ME(0.25%) but not by ME alone. Cell thining and erosion of Pinus rigida wood by the mycelia of Ferule mushroom were found only on a few cell but largely at wood block test, indicating that the softwood rotting ability of Ferule mushroom mycelia was not so good. The result of polarized light microscopy appeared that cellulose of some tracheides showing the S3 layer lost brifringence was degraded by Ferule mushroom. But only part of cellulose of P. rigida wood was degraded by Ferule mushroom, because most of wood cells continued to showing briefingence. A largely degraded ray parenchyma and longitudinal parenchyma cell and partly thinning and erosion of hardwood(Quercus serrata) cell was found and it indicates that the rotting ability of Ferule mushroom mycelia on hardwood was higher than on softwood. It could be concluded that the difference in the wood rot by Ferule mushroom between the hardwood and softwood was made by the difference of chemical constitutions between them, especially in the contents and the types of lignin. Ferule mushroom was considered as white rotter as a result of bavendam test, although more research should be required.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.84-91
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• 2020

The efficiency of the synthetic magnesium silicate used in basic polyols and edible oil purification is evaluated by its purification ability and filtration rate and is affected by the particle size and surface area of magnesium silicate. In this study, it was investigated the change on the particle size of magnesium silicate was influenced by the reaction temperature, injection rate, injection order (Si, Mg) and Mg/Si reaction mole ratio. The synthesized magnesium silicate was compared and analyzed for the synthesis, grinding, and refining processes. In the synthesis process, the reaction temperature and feed rate did not affect the average particle size change of magnesium silicate, while the reaction molar ratio of Mg / Si and the order of injection acted as main factors for the change of average particle size. The average particle size of magnesium silicate increased by 8.7 ㎛ from 54.4 ㎛ to 63.1 ㎛ at Mg injection when Mg molar ratio increased from 0.125 to 0.500, and increased by about 4.8 ㎛ from 47.3 ㎛ to 52.1 ㎛ at Si injection. The average particle size according to the order of injection was 59.1 ㎛ for Mg injection and 48.4 ㎛ for Si injection and the difference was shown 10.7 ㎛, therefore the filtration rate was about 2 times faster under the condition of Mg injection. That is, as the particle size increases, the filtration time is shortened and washing filtration rate can be increased to improve the productivity of magnesium silicate. The cake form of separated magnesium silicate after filtration becomes a solid through drying process and is used as powdery adsorbent through the grinding process. As the physical strength of the dried magnesium silicate increased, the average particle size of the powder increased and it was confirmed that this strength was affected by the reaction molar ratio. As the reaction molar ratio of Mg / Si increased, the physical strength of magnesium silicate decreased and the average particle size after grinding decreased by about 40% compared to the average particle size after synthesis. This reduction of strength resulted in an improvement of the refining ability due to the decrease of the average particle size and the increase of the amount of fine particle after the pulverization, but it resulted in the decrease of the purification filtration rate. While the molar ratio of Mg/Si was increased from 0.125 to 0.5 at Mg injection, the refining ability increased about 1.3 times, but the purification filtration rate decreased about 1.5 times. Therefore, in order to improve the productivity of magnesium silicate, the reaction molar ratio of Mg / Si should be increased, but in order to increase the purification filtration rate of the polyol, the reaction molar ratio should be decreased. In the synthesis parameters of magnesium silicate, the order of injection and the reaction molar ratio of Mg / Si are important factors affecting the changes in average particle size after synthesis and the changes of particle size after grinding due to the changes of compressive strength, therefore the synthetic parameter is an important thing that determines productivity and refining capacity.

• The Korean Journal of Mycology
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• v.10 no.2
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• pp.75-83
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• 1982

As a primary study for cell growth and alcohol production of a cider yeast, Saccharomyces sp. R-11, cultural and nutritional characteristics of the strain were investigated. The results obtained were as follows: The optimum culture medium for this strain was a synthetic medium, Henneberg B, and sucrose was the best carbon source for yeast growth and alcohol production. Optimum sugar concentrations for yeast growth and alcohol production were 15% and 25%, respectively. Optimum pH and temperature of the basal medium for growth of this strain were 4.5 and $30^{\circ}C$ respectively. The yeast growth was enhanced by the addition of 100 ppm of $Mg^{2+}$, but significantly inhibited by the addition of 100 ppm of $Co^{2+}$. Lower temperature and maintenance of optimum pH for yeast growth increased the final alcohol concentration. Under optimum condition for cell growth at stationary culture, generation time and specific growth rate of the strain were 7.5 hr and 0.092 $hr^{-1}$, respectively. At 8% initial alcohol concentration, yeast growth was inhibited about 50% and this strain could not be grown at more than 12% initial alcohol. The strain could be grown at less than 125ppm $SO_2$without alcohol addition, and at less than 75 ppm $SO_2$ with 8% initial alcohol. The higher sulfur dioxide concentration of a medium, the longer lag phase in yeast growth was observed. This strain could induced alcoholic fermentation at less than 10% initial alcohol concentration with 0 and 25 ppm $SO_2$, at less than 8% initial alcohol with 50 and 75 ppm $SO_2$, and at less than 6% initial alcohol with 100 and 125 ppm $SO_2$.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.303-309
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• 2004

Pyrochlores were known as promising materials for the immobilization of radioactive actinide. Accordingly, we synthesized pyrochlores with Gd$_2$Ti$_2$$O_7$ and Gd$_2$Zr$_2$$O_7$compositions by sintering method, and studied its properties and phase relations in Gd-Ti-O and Gd-Zr-O system. The mixed powders were pressed into pellets under 200-400 kgf/cm$^2$ at room temperature. and then sintered at 1000-1$600^{\circ}C$ for 0.5-40 hours. The synthesized samples were analyzed and were identified with XRD and SEM/EDS analyses. The optimal synthetic conditions of pyrochlores with Gd$_2$Ti$_2$$O_7$composition were at 140$0^{\circ}C$/0.5hrs, 130$0^{\circ}C$/3hrs and 120$0^{\circ}C$/20hrs. Its chemical composition was $Gd_{2.0-2.1}$$Ti_{1.9-2.0}$$O_7$ and similar to the stoichiometric composition without any relationship in temperature and atmosphere. The optimal synthetic conditions of pyrochlores with $Gd_{2}$$Zr_{2}$$O_7$composition were at 155$0^{\circ}C$/40hrs and 1$600^{\circ}C$/30hrs. The compositions of pyrochlore synthesized from these optimal conditions were irregular with $Gd_{1.5-2.4}$$Zr_{1.7-2.4}$$O_7$. Such heterogeneity indicates that the reaction rate of pyrochlore with Gd$_2$Zr$_2$$O_7$composition is very low, and then its equilibrium state could not be attained even for 40 hours which was the longest sintering time in this research.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.103-111
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• 2012

One of the basic physical properties of the hardened cement paste, the rigidity, is deteriorated during concrete matrix forming, depending on the replacement rate of the crushed stone powder, and due to drying shrinkage. Therefore, the concrete containing crushed stone powder has been limitedly used as non-structural construction material. To improve these disadvantages, a hydrothermal reaction employing method can be considered. High-temperature and high-pressure water is involved in the hydrothermal reaction in the mixing with specific materials. The rigidity improving mechanism is related to the synthesis of calcium silicate. The calcium silicate is produced through reaction between calcium compounds and the silicic acid. Various kinds of calcium silicate can be produced depending on the CaO/$SiO_2$ mole ratio, the temperature of the hydrothermal synthesis, the pressure, and the reaction time. The product of the synthesis mechanism, tobermorite crystal, plays a pivotal role for the rigidity reinforcement. The crushed stone powder, analyzed in this study, contains 50 to 60% of $SiO_2$ and 10 to 20% $Al_2O_3$. The composite rate is appropriate to create the tobermorite crystal through formation of hardened cement matrix under the hydrothermal synthetic conditions and with the CaO in the cement. Moreover, further reinforcement was promoted using the property of material under the identical density through promoting the formation of tobermorite crystal.

• The Journal of Korean Academy of Prosthodontics
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• v.22 no.1
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• pp.51-68
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• 1984

The purpose of this study is primarily to test the use value of tooth ash as an alternative material of the synthetic hydroxyapatite. For this purpose the author performed the experimental study to investigate the phsyical properties of sintered tooth ash and its histocompatibility in vitro. The tooth ash was made by incinerating procedure at $650^{\circ}C,\;750^{\circ}C,\;850^{\circ}C,\;950^{\circ}C\;and\;1050^{\circ}C$ respectively. The composition of tooth ash was analyzed and X-ray diffraction was done. The experimental specimens were molded to the cylinderical form 1 cm high, 1 cm in diameter under the pressure of $1000kg/cm^2$, which were divided into two groups; the one is sintered tooth ash at $1100^{\circ}C$ and the other is fired mixture of tooth ash and dental porcelain mixed to the weight ratio of 4:6, 5:5, 6:4 and 7:3. The physical propoerties of the sintered specimens were examined and their microstructure was observed under the Scanning Electron Microscope. The results obtained were as followings: 1. The difference of the tooth ash composition depending on incinerating temperature was of no significance, but the $CO_2$ disappeared from $950^{\circ}C$. 2. X-ray diffraction showed the tooth ash was mainly composed of hydroxyapatite and a small amount of - white lockite. But phase transformation was not disclosed. 3. The microstructure of the sintered specimens of the ashed tooth powder was of no difference in the structure and grain size accompanying the ashed temperature, but sintering ability seemed to be the best in the specimen incinerated at $950^{\circ}C$. 4. There was good wettability in the mixed sintered specimens of the ashed tooth powder and the porcelain powder. 5. The compressive strength of the sintered specimens of the tooth ash incinerated at $950^{\circ}C$ was the highest with $589.75kg/cm^2$ and the porosity and the absorption were the lowest as well. 6. The mixed sintered specimens of the tooth ash and porcelain powder was good in the physical properties in the case of mixed weight ratio of 6:4. 7. The animal fibroblast cultures with porcelain showed increase in the cell number, whereas the tooth ash showed a small degree of growth inhibition. But the difference of cell multiplication efficiency between control cultures and test cultures with tooth ash was not observed.

• KSBB Journal
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• v.11 no.3
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• pp.303-310
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• 1996

The marine microalga Isochrysis galbana Parke was studied to optimize its growth conditions in flask culture. Important medium components studied include nitrogen source, buffer, trace elements and vitamins. Environmental conditions include pH, temperature, light intensity, mixing extent and working volume. The medium prepared from natural sea-waters gave a higher final cell density than the medium prepared from synthetic sea-water Nitrate was a better source than ammonium. In the range of 0.4∼2mM, the final cell density was proportional to the initial nitrate concentration and the cell yield was estimated to be 8.5g dry cell wt/g N. For phosphate, optimal growth was observed in 0.1∼1.0mM but a considerable variation in pH was resulted. The addition of Tris at 5mM or 7mM could stabilize the medium pH, but this significantly reduced both growth rate and final cell density, The effect of trace elements and vitamins was negligible. Optimal temperature and initial pH were $20^{\circ}C$ and 8. When the intensity of incident light was varied in the range of 400∼2100 lux, the growth rate increased from 10mL to 70mL, the final cell density decreased although the initial growth rate did not change. Optimal agitation speed was 100rpm when working volume was 30mL. With optimal conditions, the maximum specific growth rate obtained was 0.021hr-1 and the final cell density was 1.1g/L.

• Resources Recycling
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• v.22 no.1
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• pp.55-63
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• 2013

Considering considerable contents of vanadium and tungsten in spent SCR DeNOx catalysts, separation and recovery of those metals are required. In this respect, commercial anion exchange resin (MP600) was employed to recover vanadium from the synthetic solution of ammonium metavanadate. Experimental results indicated that vanadium exist as anion under the acidic condition (pH 2 ~ 6) and adsorbed on the resin. Although the adsorption rate was increased with temperature, the maximum amount of adsorption was not affected by temperature. Desorption took place under either strong acidic (less than pH 1) or strong caustic (higher than pH 13) condition. However, desorption seldom took place under moderate conditions (pH 3~11). Furthermore, adsorption equilibrium results agreed well with Freundlich isotherm and pseudo-second-order reactions. And, adsorption energy was evaluated using Dubinin-Radushkevich and Temkin isotherm.