• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.66-72
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• 2009

The detection methods are required to monitor and diagnose the abnormality on the insulation condition inside a gas-insulated switchgear (GIS). Due to a good sensitivity to the products decomposed by partial discharges (PDs) in $SF_6$ gas, the development of a SWNT gas sensor is actively in progress. However, a few numerical studies on the diffusion mechanism of the $SF_6$ decomposition products by PD have been reported. In this study, we modeled $SF_6$ decomposition process in a chamber by calculating temperature, pressure and concentration of the decomposition products by using a commercial CFD program in conjunction with experimental data. It was assumed that the mass production rate and the generation temperature of the decomposition products were $5.04{\times}10^{-10}$ [g/s] and over 773 K respectively. To calculate the concentration equation, the Schmidt number was specified to get the diffusion coefficient functioned by viscosity and density of $SF_6$ gas instead rather than setting it directly. The results showed that the drive potential is governed mainly by the gradient of the decomposition concentration. A lower concentration of the decomposition products was observed as the sensors were placed more away from the discharge region. Also, the concentration increased by increasing the discharge time. By installing multiple sensors the location of PD is expected to be identified by monitoring the response time of the sensors, and the information should be very useful for the diagnosis and maintenance of GIS.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.385-392
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• 2009

This study was conducted to reclassify Namweon series, black volcanic ash soils, in Jeju Island based on the second edition of Soil Taxonomy : A Basic System of Soil Classification for Making and Interpreting Soil Surveys. Morphological properties of typifying pedon of Namweon series were investigated and physicochemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Namweon series has black (10YR 2/1) silt loam Ap horizon (0~11 cm) and black (10YR 2/1) silt loam BA horizon (11~72 cm). Bw horizon (72~100 cm) is very dark brown (10YR 2/2) silt loam. That occurs on lava plain derived from volcanic ash materials. The typifying pedon contains 5.2~6.4% oxalate extractable (Al + 1/2 Fe), over 85% phosphate retention, and lower bulk density than $0.90Mg\;m^{-3}$. Ap, BA, and Bw horizons of the pedon have andic soil properties. That can be classified as Andisol. The typifying pedon has an udic soil moisture regime and has a 1,500 kPa water retention of 15% or more on air-dried samples throughout all horizons, and can be classified as Udand. Ap and BA horizons (0~72 cm) have a color value, moist, and chroma of 2 or less, melanic index of 1.70 or less, and 6% or more organic carbon. That meets the requirements of melanic epipedon. That keys out as Melanudand. That has more than 6.0% organic carbon and the colors of mollic epipedon throughout a layer 50 cm or more thick within 60 cm of the mineral soil surface.. Thus, that keys out as Pachic Melanudand. The pedon has a fine-earth fraction that has a water content at 1,500 kPa tension of 12% or more on air-dried samples and has less than 35% (by volume) rock fragments. Thus, the substitute for particle-size class is medial. That has a sum of 8 times the Si (percnt by weight extracted by acid oxalate) plus 2 times the Fe (percnt by weight extracted by acid oxalate) of 5 or more, and 2 times the Fe is more than 8 times the Si. Thus, the mineralogy class is ferrihydritic. Namweon series can be classified as medial, ferrihydritic, thermic family of Pachic Melanudands, not as ashy, thermic family of Typic Melanudands.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.4
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• pp.11-19
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• 2018

This study was conducted to develop the manufacturing method of biochar using pruned stems of pear tree and its application effect on the crop growth and soil physico-chemical properties. In this study, biochar derived from pruned stems of pear tree at heating temperature of $300^{\circ}C$, $500^{\circ}C$ and $700^{\circ}C$ in heating times of 2, 3 and 4 hours, were tested in the changes of their chemical properties during biochar processing. The pH, Exch. K, Exch. Mg and cation exchange capacity (CEC) increased as the pyrolysis temperature increased during the production of biochar, and the change of these properties rapidly occurred at $500^{\circ}C$. However, as the pyrolysis temperature increased, ash content increased and total carbon (T-C), yield decreased. And the change of the properties in response to the heating time was not shown. It was thought that it would be desirable to set the production conditions of biochar at $500^{\circ}C$ for 2 hours in consideration of the change of chemical properties and the ash content and yield. And also, were conducted the experiments to establish manufacturing method of farm-made biochar using drum biochar manufacturing machine and investigate the application effects of biochar on the cultivation of chinese cabbage and tomato. Application of biochar derived from pruned stems of pear tree could enhance pH, organic matter (OM), total carbon (T-C) of soil. On the other hand, soil electrical conductivity (EC), NO3-N were lowered compared to the control which has no application. The bulk density, porosity and aggregate formation of soil were improved by biochar application. The fresh matter yields of chinese cabbage and tomato were significantly increased in proportion to the application rate of biochar. This study demonstrated the effect of the biochar derived from agricultural byproduct to be as a low cost potential soil ameliorant by physico-chemical properties in eco-friendly greenhouse cultivation.

• Journal of Mushroom
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• v.20 no.3
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• pp.168-172
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• 2022

This study was conducted to investigate the optimum supplementation ratio when replacing cotton seed meal with rapeseed meal for cultivating oyster mushrooms. The chemical properties among the treatments were pH 4.5~4.7, total carbon content was 46.3~46.5%, total nitrogen content was 1.6~1.7%, and carbon-nitrogen ratio was 27.0~27.8. These did not differ significantly from the control. Mycelial growth was 85.1 mm (Heuktari), and 72.8 mm (Suhan-1Ho) in medium containing 5% rapeseed meal, with no significant difference in mycelial density between cultivars. Fruiting body characteristics are as follows: In 'Heuktari', the color of the pileus was darker than control with an L value of 32.5, and pileus thickness and diameter were 3.2 mm and 27.6 mm, respectively. Stipe length and diameter were 86.0 mm and 9.1 mm, respectively. Valid stipe number per bottle (1,100 cc) was 25.9, and a yield of 189.7 g/1,100 cc was recorded in mixed medium containing 5% rapeseed meal (higher than control). In mixed medium containing 10% rapeseed meal, the yield was 184.5 g/1,100 cc (comparable to control). In 'Suhan-1Ho', supplemented with 5% rapeseed meal, pileus color was darker than control color, with an L value of 28.8. Pileus thickness was 4.5 mm. Stipe diameter was 12.3 mm (higher than control), and yield was 145.5 g/1,100 cc (comparable to control).

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.73-82
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• 2023

This study was conducted to investigate the effect of soil physico-chemical properties and crop growth responses for application of biochar derived from substrate with post harvest of oyster mushroom. The biochar was produced at 450~600℃ using a top-light up draft gasifier (TLUD) production system. As a result of elemental analysis, the biochar used was C 76.2%, H 2.5%, N 3.2%, and H/C was 0.39, which met the international certification standards for biocarbons (IBI) below 0.7. The chemical properties were 10.1 for pH, 1.0% for P₂O₅, 1.8% for K₂O, and 2.5% for CaO. The application rates of biochar were 0, 100, 200, 300, and 500 kg/10a. For cultivation of chinese cabbage and welsh onion, soil organic matter (OM), total nitrogen (T-N), total carbon (T-C), Ex.cation K contents and cation exchange capacity (CEC) in the treatments were increased compared to the no treatment. In addition, the bulk density was lowered and the porosity was increased, improving the soil physical properties in the treated soil. The growth of chinese cabbage and green onion increased with the application of biochar, but the yields of chinese cabbage and green onion did not significantly different among the treatments. Soil carbon sequestration in the treatments enhanced with increasing the amount of biochar application. It is expected to apply the biochar derived from spent oyster mushroom substrate in the eco-friendly farm soil management, improving soil physico-chemical properties.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.426-438
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• 2023

Lithium-sulfur batteries, recently attracting attention as next-generation batteries, have high energy density but are limited in application due to sulfur's insulating properties, shuttle phenomenon, and volume expansion. This study used an economical and simple vacuum filtration method to prepare a freestanding electrode without a binder and collector. Carbon nanotubes (CNTs) are used to improve the electrical conductivity of sulfur, where CNT also acts as both collector and conductor. In addition, metal oxides (MO_x, M=Ni, Mg), which are easy to adsorb lithium polysulfide, are added to the CNT/S electrode to suppress the shuttle reaction in lithium-sulfur batteries, which is a result of suppressing the loss of active sulfur material due to the excellent adsorption of lithium polysulfide by metal oxides. The MO_x@CNT/S electrode exhibited higher capacity characteristics and cycle stability than the CNT/S electrode without metal oxides. Among the MO_x@CNT/S electrodes, the NiO@CNT/S electrode displayed a high discharge capacity of 780 mAh g^-1 at 1 C and an extreme capacity decrease to 134 mAh g^-1 after 200 cycles. Although the MgO@CNT/S electrode exhibited a low discharge rate of 544 mAh g^-1 in the initial cycle, it showed good cycle stability with 90% of capacity retention up to 200 cycles. Further, to achieve high capacity and cycle stability, the Ni_0.7Mg_0.3O@CNT/S electrode, mixed with Ni:Mg in the ratio of 0.7:0.3, manifested an initial discharge rate of 755 mAh g^-1 (1 C) and a capacity retention rate of more than 90% after 200 cycles. Therefore, applying binary metal oxides to CNT/S provides a freestanding electrode for developing economical and high-performance Li-S batteries, effectively improving lithium polysulfide's high capacity characteristics and dissolution.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.3
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• pp.201-207
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• 2007

To reduce both the floatation of the seedling of rice and the failure in standing in the paddy field when the barley straw was applied to paddy field before planting the rice, we tested the effect of rice rooting with plowing methods and irrigation rates for 2 years from 2003 to 2004. This study was carried out in paddy field with Fluvio-Marine deposit in Jeonbug series and the operating accuracy and the change of soil physico-chemical properties depending on plowing methods and irrigation rates following the barley straw applying were examined. There was a less floatation of barley straw in the dry-rotaryI+water-rotaryI(DRI+WRI) plot than in the plowing+water-rotary(PL+WRI) plot. The ratio of miss-planted and floating seedling also decreased by 1.7%, 2.6% in the DRI+WRIplot compared with PL+WRI plot. The soil physical property was improved with the decreasing soil hardness, bulk density and increasing soil porosity after the application of barley straw, especially enhanced greatly in the increase of porosity, gaseous phase and with the decrease of soil hardness, bulk density of subsurface soil in DRI+WRI plot. And the change of soil chemical property were increased the content of total carbon$^{\circ}{\S}$nitrogen$^{\circ}{\S}$organic matter and available phosphate while decreased the content of exchangeable cations and available silicate after the application of barley straw. Also the content of organic matter, available phosphate and cation exchangeable capacity were increased, whereas caron/nitrogen ratio was decreased in DRI+WRI plot compared with PL+WRI plot. The number of panicles, spikelets per square meter were increased and 1,000 grains weight of hulled rice was gained more in DRI+WRI plot at irrigation rate of $500ton\;ha^{-1}$, in DRI+WRII plot at irrigation rate of $700ton\;ha^{-1}$. So the rice yields were increased by 7%, in DRI+WRI and 5% in DRI+WRII plot, respectively compared with PL+WRI plot. The result of this study indicated that the most appropriate plowing method with barley straw application on rice cultivation at double cropping in normal paddy field plain land was DRI+WRI.

• Microbiology and Biotechnology Letters
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• v.26 no.5
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• pp.435-441
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• 1998

Optimal conditions for the production of natural color, betacyanin were investigated by varying light intensity, C/N ratio, concentrations of phosphate and kinds of elicitors. Batch cultivation was employed to characterize cell growth and betacyanin production of 32 days. The maximum specific growth rate, ${\mu}$$\sub$max/, was 0.3 (1/day) for batch cultivation. The maximum specific production rate, q$\^$max/$\sub$p/, was enhanced 0.11 (mg/g-cell/day) at 3 klux. A light intensity of 3 klux was shown to the best for both cell growth and betacyanin production. The maximum specific production rate was 0.125 (mg/g-cell/day) at 0.242 (1/day), the maximum specific growth rate. The dependence of specific growth rate on the light lintensity is fit to the photoinhibition model. The correlation between ${\mu}$ and q$\sub$p/ showed that the product formation parameters, ${\alpha}$ and ${\beta}$$\sub$p/ were 0.3756 (mg/cell) and 0.001 (mg/g-cell/day), respectively. The betacyanin production was partially cell growth related process, which is different from the production of a typical product in plant cell cultures. In C/N ratio experiment, high carbon concentration, 42.1 (w/w) improved cell growth rate while lower concentration, 31.6 (w/w) increased the betacyanin production rate. The ${\mu}$$\sub$max/ and q$\^$max/$\sub$p/ were 0.26 (1/day) and 0.075 (mg/g-cell/day), respectively. Beta vulgaris L. cells under 1.25 mM phosphate concentration produced 10.15 mg/L betacyanin with 13.46 (g-dry wt./L) of maximum cell density. The production of betacyanin was elongated by adding 0.1 ${\mu}$M of kinetin. This also increased the cell growth. Optimum culture conditions of light intensity, C/N, phosphate concentration were obtained as 5.5 klux, 27 (w/w), 1.25 mM, respectively by the response surface methodology. The maximum cell density, X$\sub$max/, and maximum production, P$\sub$max/, in optimized conditions were 16 (g-dry wt./L), 12.5 (mg/L) which were higher than 8 (g-dry wt./L), 4.48 (mg/L) in normal conditions. The ${\mu}$$\sub$max/ and q$\^$max/$\sub$p/ were 0.376 (1/day) and 0.134 (mg/g-cell/day) at the optimal condition. The overall results may be useful in scaling up hairy root cell culture system for commercial production of betacyanin.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.327-339
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• 2001

Community structure of macrobenthos was studied at forty one stations of Hampyung Bay, southwest coast of Korea. Three replicate sediment samples were taken at each station in October 1997, using a van Veen grab (surface area $0.1\;m^2$). The types of surface sediment in the sampling area were muddy sandy gravel between bay mouth and bay proper, and gravelly sandy mud between bay proper and inner bay stations. The particulate organic carbon content in the surface sediment was $0.23\sim0.69\%\;(0.44\pm0.10\%)$. A total of 168 species collected during the study period is composed of 58 of polychaetes, 54 of crustaceans, 34 of molluscs and 22 of miscellaneous. The former two taxa together were accounted for $66.6\%$ of the total number of species. The mean density was $1,168 ind./m^2$, comprising $684 ind./m^2$of molluscs ($58.6\%$), $381 ind./m^2$of polychaetes ($32.6\%$), and $90 ind./m^2$of crustaceans ($13.2\%$). The mean biomass was $358.65 g/m^2$, which is consisted of $302.97 g/m^2$of molluscs ($84.5\%$), $24.20 g/m^2$of echinoderms ($6.7\%$), and $19.16 g/m^2$of crustaceans ($5.4\%$). Major dominant species at the inner stations of the study area was Ruditapes philippinarum with a density of $520ind./m^2$($44.5\%$), and Lumbrineris lontifolia with $183ind./m^2$($15.7\%$), while that at bay mouth stations Pitar indecoroides with $56ind./m^2$. Reticunassa festiva, Heteromastus sp., Praxillella affinis, Chone sp. and Tharyx sp. were at from all stations. Based on the cluster analysis, the macrobenthic community in the bay was classified into five station groups depending on sediment types: Group A, a high gravel content in the sediment; Group B, stations with high mud content from bay mouth to bay proper, Group C, stations with fine and poorly sorted sediment from bay proper to the inner bay. The distribution pattern of the number of species, abundance and biomass is discussed in relation to environmental variables.

• Journal of Periodontal and Implant Science
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• v.26 no.2
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• pp.469-490
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• 1996

The initial events required for periodontal regeneration is the attachment, spreading, and proliferation of appropriated cells at the healing sites. These have been reported that minocycline stimulates the attachment of periodontal ligament cells, and also $TGF-{\beta}1$ enhances the proliferation of periodontal ligament cells. The purpose of the present study was to evaluate the effects of $TGF-{\beta}1$ on the cellular activity of minocycline treated human periodontal ligament cells. Periodontal ligament cells were obtained from the explants of healthy periodontal ligaments of extracted 3rd molars or premolar teeth extracted from the patients for orthodontic treatment. The cells were cultured in minimal essential medium(${\alpha}-MEM$) supplemented with 10.000units/ml penicillin, $10,000{\mu}g/ml$ streptomycin and 10% FBS(fetal bovine serum) at $37^{\circ}C$ in a humidified atmosphere of 5% carbon dioxide and the 5th to the 8th passages of the cells were used. To evaluate the effect of minocycline on cell attachment, the cells were seeded at a cell density of $1.5{\times}10^4$ cells/well in 24-well culture plates and treated with $20{\mu}g/ml$ and $100{\mu}g/ml$ of minocycline for 1.5 h. After trypsinization, the cells were counted with hemocytometer and were taken photographs for observation of cellular morphology. To evaluate the effect of $TGF-{\beta}1$ on minocycline-pretreated periodontal ligament cells, the cells were seeded at a cell density of $1{\times}10^4$ cells/ well in 24-well culture plates and treated with $20{\mu}g/ml$ and $100{\mu}g/ml$ of minocycline for 1.5 h. After incubation, 1 and 10ng/ml of $rh-TGF-{\beta}1$ were also added to the each well and incubated for 1 and 2 days, respectively. Then, MTT assay, DNA synthesis($^3H-thymidine\;assay$), and protein and collagen assay(3H-proline assay) were carried out. In the MIT assay, after 200ul MTT solutionlconeentration of 5mg/ml) were added to the each well of the 24-well plates and incubated for 3 hours, and 200 ul DMSO were added so as to dissolve insoluble blue formazan crystals which was formed in incubated period. Then it read plates on a ELISA reader. For mitogenic assay, 1 uCi/ml $^3H-thymidine$ was added to each well for the final 2 hours of the incubation periods. After labeling, the wells were washed 3 times with ice cold PBS and 4 times with 5% TCA to remove unincorporated label and precipitate the cellular DNA. DNA, with the incorporated $^3H-thymidine$, was solubilized with 500 ul of 0.1% NaOH/0.1% SDS. A 250 ul aliquot was removed from each well and placed in a scintillation vial with 4ml of scintillation cocktail. Using an liguid scintillation counter, counts per minute(CPM) were determined for each samples. 3 uCi/ml $^3H-proline$ was added to each well for the final 4 hours of the incubation periods and total protein and percent collagen synthesis were carried out. The results indicate that minocycline treated group with $100{\mu}g/ml$ concentration for 1.5 hours significantly increased than that of control in cell attachment, and cell process is also evident compared with that of control in cell morphology, and the cellular activity and DNA synthesis rate of cells treated minocycline and $TGF-{\beta}1$ significantly increased than that of control values, but were below to values of the $TGF-{\beta}1$ only treated group in MIT assay and $^3H-thymidine\;assay$, and the total protein synthesis of minocycline and $TGF-{\beta}1$ treated group also significantly increased than that of control values, but the percent collagen synthesis of tested group significantly decreased to compared with control. On the above the findings, the tested group of minocycline and $TGF-{\beta}1$ did not increase the effect on the cell activity than $TGF-{\beta}1$ only tested group and the tested group of minocycline inhibited cell activity. This results indicate that minocycline was effective on cell attachment in early stage, but it is harmful to cell activity, that inhibitory effect of minocycline was compensated with stimulatory effect of $TGF-{\beta}1$.