• Progress in Superconductivity and Cryogenics
• /
• v.19 no.3
• /
• pp.40-43
• /
• 2017

Carbon coating approach is used to prepare carbon-doped $MgB_2$ bulk samples using low-cost naphthalene ($C_{10}H_8$) as a carbon source. The coating of carbon (C) on boron (B) powders was achieved by direct pyrolysis of naphthalene at $120^{\circ}C$ and then the C-coated B powders were mixed well with appropriate amount of Mg by solid state reaction method. X-ray diffraction analysis revealed that there is a noticeable shift in (100) and (110) Bragg reflections towards higher angles, while no shift was observed in (002) reflections for $MgB_2$ doped with carbon. As compared to un-doped $MgB_2$, a systematic enhancement in $J_c(H)$ properties with increasing carbon doping level was observed for naphthalene-derived C-doped $MgB_2$ samples. The substantial enhancement in $J_c$ is most likely due to the incorporation of C into $MgB_2$ lattice and the reduction in crystallite size, as evidenced by the increase in the FWHM values for doped samples.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.5
• /
• pp.519-524
• /
• 2005

Due to the low C/N ratio of domestic wastewater characteristic, addition of external carbon source for the effective N and P removal is necessary. High organic content of food waste can be used for the external carbon source in biological nutrient removal processes, The applicability of condensate of food waste (CFW), which is produced during the high-rate fermentation process, was examined in membrane bioreactor for the nutrient removal. Under the various operating conditions, nutrient removal efficiencies and membrane fouling characteristics were evaluated using synthetic wastewater. From nitrate utilization rate (NUR) test, denitrification rate was 0.19 g $NO_3-N/g$ VSS/day. With the addition of CFW increased, average removal efficiencies of T-N and T-P could be increased up to 64% and 41%, respectively. Also the optimal retention time was 3 hr/5 hr for anoxic/aerobic reactor. When applied to real sewage, membrane fouling resistance was increased up to 60%, which could be reduced from $10.4{\times}10^{12}m^{-1}$ to $5.9{\times}10^{12}m^{-1}$ with the control of influent suspended solid concentration. In summary, it was suggested that CFW could be used as an economical and effective carbon source for membrane assisted biological N and P removal.

• The Korean Journal of Mycology
• /
• v.24 no.4 s.79
• /
• pp.274-279
• /
• 1996

An isolate of Lepista nuda was cultivated on the solid media consisted of various cereal grains or those of the acacia sawdust mixed with other cereal grains. The mycelia grew well on the solid cultures made from millet cereals, but did not on those from sorghum or corn cereals. Thus, the millet and the acacia sawdust, as the solid media, were employed for the next experiments related to mycelial growths. For growth of this isolate, it was shown that the nitrogen source is needed for those of millet. Also, the rice bran or minerals were considered to be needed for the acacia sawdust. As minerals, however, the rice bran is shown as the best additive in the solid cultures of the acacia sawdust. The mycelia of L. nuda were cultivated directly through the solid cultures. Their growths were measured' by the production of carbon dioxide with gas chromatography.

• Journal of the Korean Institute of Gas
• /
• v.27 no.3
• /
• pp.27-34
• /
• 2023

Using ammonia as fuel for solid oxide fuel (SOFC) cells has become an attractive topic nowadays due to its high efficiency, environmental friendliness, and ease of storage and transportation. Several configurations of ammonia-fed SOFC systems have been proposed and investigated, demonstrating high electrical efficiency. However, to further enhance efficiency, it is crucial to understand the inefficient components of the system. The exergy concept is well-suited for this purpose, making exergetic analysis essential for ammonia-fed SOFC systems. This study conducts an exergetic analysis for three selected systems: a simple fuel cell system (FC), an anode off-gas recirculation system (RC-FC), and a recirculation system with water removal (RC-WR-FC). The results reveal that the exergetic efficiencies of the FC, RC-FC, and RC-WR-FC are 48.7%, 51.6%, and 58.4%, respectively. In all three systems, the SOFC stack is the main source of exergy destruction. However, other components with relatively low exergetic efficiency, such as the burner, air heat exchanger, and cooler/condenser, offer greater opportunities for improvement.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.11
• /
• pp.1503-1512
• /
• 2002

From the view of the environmental protection against the use of fossil fuels, a great of efforts have been exerted to find an alternative energy source. Hydrogen may become an alternative However the product species of the hydrogen flame is only $H_2O$, which emits only non-luminous radiation so the radiation from it is much smaller than that for a hydrocarbon flame. In this study, the authors designed and fabricated a laboratory scale test furnace to study thermal characteristics of hydrogen-air diffusion flame. In addition. the effects of addition of reacting as welt as non-reacting solid particles were experimentally investigated. Among the total heat flux to the wall, about 75 % was occupied by radiation while 25% by convection. When the aluminum oxide (Al$_2$O$_3$) particles were added, the radiative heat flux was reduced due to heat blockage effects. On the other hand, the total as well as the radiative heat flux was increased when the carbon particles were seeded, since the overall temperature increased. The effects of swirl and excess air ratio were also examined.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.10 no.1
• /
• pp.78-84
• /
• 2005

The purpose of this study was to optimize the solid state cultivation of Monascus ruber on sterile rice. A single-level-multiple-factor and a single-factor-multiple-level experimental design were employed to determine the optimal medium constituents and to optimize carbon and nitrogen source concentrations for lovastatin production. Simultaneous quantitative analyses of the ${\beta}$-hydroxyacid form and ${\beta}$-hydroxylactone for of lovastatin were performed by the high performance liquid chromatography (HPLC) method with a UV photodiode-array (PDA) detector. The total lovastatin yield ($4{\sim}6\;mg/g$, average of five repeats) was achieved by adding soybean powder, glycerol, sodium nitrate, and acetic acid at optimized levels after 14 days of fermentation. The maximal yield of lovastatin under the optimal composition of the medium increased by almost 2 times the yield observed prior to optimization. The experimental results also indicated that the ${\beta}$-hydroxylactone form of lovastatin (LFL) and the ${\beta}$-hydroxyacid form of lovastatin (AFL) simultaneously existed in solid state cultures of Monascus ruber. while the latter was the dominant form in the middle-late stage of continued fermentation. These results indicate that optimized culture conditions can be used for industrial production of lovastatin to obtain high yields.

• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.2
• /
• pp.93-104
• /
• 2020

As water resources are limited and legal regulations are strengthened, there is a growing need to reuse residuals in WTP(Water Treatment Plant). In this study, membrane filtration system was constructed and its operation method was studied for water quality stabilization and reuse of WTP residuals. The operation parameters were stable for 1 year and 6 months. Membrane fouling was identified as particulate pollution (activated carbon) and inorganic pollution (manganese). The membrane system was operated steadily with raw water of high concentration SS(Suspended solid) containing activated carbon because membrane fouling was reduced by the effect of End-Free type. In the case of inorganic contamination, dissolved manganese eluted by chemicals and acted as a membrane fouling source, and the operating conditions for minimizing membrane fouling. were confirmed by newly developing application methods and types of cleaning chemicals. Based on the results, design parameters for reducing manganese membrane fouling were derived.

• Mycobiology
• /
• v.28 no.1
• /
• pp.33-38
• /
• 2000

Mycelium of Hericium erinaceum isolate KU-1 was cultured in liquid medium (HL medium) and solid medium (Ko medium) at pH 4.0 in $28^{\circ}C$. 1.0% glucose or fructose was the most favorable carbon source, and 0.2% amonium acetate or $NaNO_3$ was an exellent nitrogen source for mycelial growth as well as production of antimicrobial substances. The mixture of saw dust 70% with rice bran 30% (SR medium) was the substrate for formation of sporophores. The active substrates in extracts from mycelium, culture filtrate and fruiting body were separated by TLC. The solvent for TLC was EtOAc: Chloroform: MeOH (10 : 5 : 10). Phenol-like substances appeared at Rf $0.5{\sim}0.9$, and fatty acid-like substances appeared at Rf $0.1{\sim}0.2$. The purified materials from the extracts showed antimicrobial effects to Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Aspergillus niger, Candida albicans and Microsporum gypseum. The S. aureus was the most inhibited. Minimal inhibitory concentration (MIC) of purified white powder and the Hercenone derivatives against S. aureus were $5.65\;{\mu}g/ml$ and $1.85\;{\mu}g/ml$, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.150-150
• /
• 2016

Mankind is enjoying a great convenience of their life by the rapid growth of secondary industry since the Industrial Revolution and it is possible due to the invention of huge power such as engine. The automobile which plays the important role of industrial development and human movement is powered by the Engine Module, and especially Diesel engine is widely used because of mechanical durability and energy efficiency. The main work mechanism of the Diesel engine is composed of inhalation of the organic material (coal, oil, etc.), combustion, explosion and exhaust Cycle process then the carbon compound emissions during the last exhaust process are essential which is known as the major causes of air pollution issues in recent years. In particular, COx, called carbon oxide compound which is composed of a very small size of the particles from several ten to hundred nano meter and they exist as a suspension in the atmosphere. These Diesel particles can be accumulated at the respiratory organs and cause many serious diseases. In order to compensate for the weak point of such a Diesel Engine, the DPF(Diesel Particulate Filter) post-cleaning equipment has been used and it mainly consists of ceramic materials(SiC, Cordierite etc) because of the necessity for the engine system durability on the exposure of high temperature, high pressure and chemical harsh environmental. Ceramic Material filter, but it remains a lot of problems yet, such as limitations of collecting very small particles below micro size, high cost due to difficulties of manufacturing process and low fuel consumption efficiency due to back pressure increase by the small pore structure. This study is to test the possibility of new structure by direct infiltration of SiC Whisker on Carbon felt as the next generation filter and this new filter is expected to improve the above various problems of the Ceramic DPF currently in use and reduction of the cost simultaneously. In this experiment, non-catalytic VS CVD (Vapor-Solid Chemical Vaporized Deposition) system was adopted to keep high mechanical properties of SiC and MTS (Methyl-Trichloro-Silane) gas used as source and H2 gas used as dilute gas. From this, the suitable whisker growth for high performance filter was observed depending on each deposition conditions change (input gas ratio, temperature, mass flow rate etc.).

• KSBB Journal
• /
• v.28 no.3
• /
• pp.213-215
• /
• 2013

A high-throughput screening strategy was developed to simplify the selection process for improved mannitol producing strain after chemical mutagenesis. Ethylmethyl sulfonate (EMS) was used as a chemical mutagen to alter the fructokinase-I gene which is an essential enzyme to metabolize fructose for growth. Leuconostoc mesenteroides treated with EMS were plated on the modified MRS solid medium containing fructose as a sole carbon source. Strains showing inhibited growth were primarily selected to evaluate the mannitol producing ability. By applying this strategy, L. mesenteroides ATCC 8293 M1, L. mesenteroides ATCC 9135 M3 and L. mesenteroides D1 M3 showed improvement in mannitol production.