• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.145-150
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• 2020

Water wall tube is one of the major factors consisting of a fluidized bed boiler and it plays very important role for the generation of electricity within the boiler. But these water wall tubes within the fluidized bed boiler are subject to the ware and corrosion caused by the high temperature gas and the flowing medium. If water leak is occurred, the secondary damage by the water leak will occur. As a result of that, the power generation efficiency decreases noticeably. Therefore, the maintenance of the water wall tube is very important. In this study, we designed a exciter sensor based on simulation and composed a remote field eddy current system for the defect evaluation of the outer water wall tube. Starting from the shape design of exciter, we conducted simulations for various design factors such as the water wall tube size, material, frequency, lift-off and so on. Based on the results, we designed the optimum exciter sensor for the water wall tube test within the fluidized bed boiler.

• Korean Journal of Microbiology
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• v.44 no.4
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• pp.352-357
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• 2008

We evaluated cultivation methods to obtain pure cultures of previously uncultivated bacteria from soil. Soil bacteria (suspensions) were inoculated onto various oligotrophic media with one of the following additives: 1) soil extract; 2) anthraquinone disulfonate (humic acid analogue); 3) acyl homoserine lactones (quorum-signaling compounds); 4) catalase (for the protection of bacteria from exogenous peroxides). After the relatively long period (60 days) of incubation with elevated concentrations of $CO_2$ (5%, v/v), the media containing catalase showed the highest colony count. We purified 147 randomly selected colonies from the media and the isolates were subjected to the phylogenetic analyses of their 16S rRNA gene sequences. Phylogenetic analysis revealed that approximately 30% of the isolates might belong to novel species or novel family, suggesting that the media and incubation conditions used could be useful for the cultivation of as-yet-uncultured bacteria. Especially, bacteria belonging to the phylum Acidobacteria, ubiquitous bacterial taxon known as an uncultured bacterial group (at least difficult to culture from environmental samples), were successfully cultured in this study.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.883-887
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• 1998

Protease activities were measured in vegetables used as cooking material or a side dish. Proteases of green pepper (Kwari and Chungyang), perilla leaves, soybean sprout and mungbean sprout were showed high activities. Especially, protease in soybean sprout was the highest activity among them. After dialysis, remaining activities in mungbean sprout, green pepper (Kwari and Chungyang) and perilla leaves were 12, 23, 45% and 37%. In the results of thawing after freezing the proteases, remaining activities in sprout of mungbean and soybean were 100% and 65%. Protease in soybean sprout was showed higher activity and stability than others. Proteolytic effects of soybean sprout on myofibrillar and sarcoplasmic protein were showed higher than stroma protein. In SDS-PAGE, myosin heavy chain, actin and tropomyosin were hydrolyzed with increasing time. Protease activity was rapidly increased with increasing meat concentration in a early proteolysis reaction, but was slightly increased in later.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.92-95
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• 2019

In this paper, a novel laser-based non-contact and non-destructive stress measurement technique is newly proposed for measuring stress in steel structural members. As the demand of stress monitoring in structural members is increased, various non-destructive techniques are being applied to the field of structural health monitoring. Spectroscopic techniques are non-contact technique and widely used for chemical identification of target materials. Especially, piezospectroscopic technique is a residual stress measurement technique in thermal barrier coatings. Although the piezospectroscopic technique has high possibility of measuring structural stress in steel members, the technique has been rarely applied to this field. In this paper, piezospectroscopy-based stress measurement technique is, therefore, proposed for measuring stress in steel structural member. To do that, alumina particles have been coated onto a specimen of a structural steel rod using a thermal spray coating technique. And then, an uniaxial compression test has been conducted to the specimen to collect each fluorescence spectrum under different loading conditions. Finally, the linear relation of spectral shift and applied compressive stress of the specimen has been experimentally established.

• Applied Biological Chemistry
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• v.18 no.4
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• pp.203-218
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• 1975

In order to investigate the compositional change oil composts during the growing of cultivated mushroom (Agaricus bisporus), composts and mushrooms during the period of filling to ending under commercial conditions were subjected to chemical analyses. The results are summarized as follows and the mechanism of composting for mushroom cultivation was proposed. 1) The temperature change of growing bed and room was observed and the yield of mushroom for each cropping time was recorded to get $15.6kg/m^2$ in total crops. 2) Composts after filling showed pH 8.2 which dropped to 6.4 after casing and continued so up to ending. 3) On the dry weight basis of composts, crude ash increased whereas total nitrogen, ether extract and crude fibre decreased gradually to bring about the lowering of organic matter. 4) Total nitrogen of composts decreased gradually and more insoluble nitrogen was lost than soluble nitrogen. The C/N ratio of composts was initially 21 which was gradually lowered to 16. 5) The losses of ${\alpha}-cellulose$, pentosan and lignin in composts were 87%, 75%, and 60%, respectively, in which ${\alpha}-cellulose$ decreased markedly after casing. 6) Free reducing sugars of composts increased continuously. Gradually increased free amino acids till second cropping decreased again thereafter. Composts at the filling stage contained alanine, glutamic acid, glycine and serine in which glycine decreased markedly whereas proline increased remarkably upon mushroom cultivation. 7) Among minerals of composts, phosphorus and zinc tended to decrease, potassium and copper tended to increase anti sodium showed no marked change. 8) In comparison of mushrooms from different cropping time with respect to proximate composition, minerals, free reducing sugars and amino acids, no marked difference was observed. However, a little higher values were observed in crude fat, free reducing sugars and sodium content for early crops and in free amino acids and phosphorus content for late crops. Twelve free amino acids including alanine, serine, threonine, and glutamic acid were detected in the cultivated mushroom. 9) According to above experimental results, it was possible to support the mechanism of compositing that the formation of ammonia and decomposition of carbohydrates by mesophiles are followed by protein biosynthesis, formation of microbial bodies and nitrogen-rich lignin humus complex by thermophiles, thus supplying necessary nutrients for mushroom growth, along with residual carbohydrates.

• Journal of Bio-Environment Control
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• v.9 no.3
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• pp.166-170
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• 2000

Three methods for heat collection, which were the flat solar collector, two fan with radiator, and square pipe method, were studied to sue efficiently solar energy in the three different glasshouses for two years. The flat plate solar collector method was made use of the commercial solar collector with collection area of 24$m^2$, the method of two fans with radiators collected solar energy at the top of the glasshouse. An thermal storage tank was constructed underneath in teach glasshouses. When an area of 1,000$m^2$ was heated to the minimum temperature of 9$^{\circ}C$, the decrease rate of heating fuel for the flat plate solar collector, the fan attached radiator and the square pipe methods were 7%, 19% and 28% respectively. The flat plate solar collector method, which could be heated approximately 40-50$m^2$, was currently used by most of the farmer. Under the condition, the decrease rate of annual heating fuel was 14% which was not better for an economic annual heating fuel. If the fan with radiator method was operated, the use of installation and maintenance were required. So, it could not be good economic efficiency of solar heating. The heating efficiency of the square pipe method was relatively better thant those of the flat plate solar collector or the fan attached radiator. Since the cost of materials and its installation of the use of square pipe method was lower than any other method. However, corrosion of the pipe, greater shade in the greenhouse and strength against the square pipe were problems that should be overcome in the square pipe method.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.326-340
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• 2016

GHS was compared with that of current RDA directives in skin and eye irritation for plant protection products (PPPs). According to the result of evaluation and classification of skin and eye irritation by RDA directives and GHS for 59 PPPs, 25.5% of PPPs were changed the classification of skin irritation from slightly and moderately by RDA directives to Not Classified by GHS, and 45.8% of PPPs were changed the classification of eye irritation from slightly by RDA directives to Not Classified by GHS. 6.8% of PPPs in skin irritation and 5.1% in eye irritation were classified more highly as category 1 by GHS because of irreversible effect. According to the result of comparison with GHS classification by data of irritation study for PPPs and by GHS classification and concentration of active substances, 25.5% was changed more lowly and 3.4% more highly in skin irritation, and 25.4% was changed more lowly and 11.9% more highly in eye irritation. It is needed to draw a plan to supplement for other results between GHS and RDA directives.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.2
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• pp.115-120
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• 1999

This experiment was carried out to investigate the effects of additives on the quality of alfalfa(Medicago sativa L.) silage at the forage experimental field, National Livestock Research Institute, RDA, Suwon in 1996. The experiment was arranged in a randomized block design with three replications. The treatments consisted of different additives(control, formic acid, molasses, inoculant A and inoculant B). Crude protein(CP) and Nitrogen free extract(NFE) content of alfalfa silage with additives were higher compared with those obtained control, but Crude ash(CA) and Crude fiber(CF) content of control(11.5 and 39.6%) were higher than those of additive treated plots. ADF and NDF contents of control silage were the highest as 36.2 and 48.6%, respectively, and increased by 4% compared with those obtained before ensiling. The acidity(pH) of control was the highest(5.45), but the lowest in inoculant A(4.32). Inoculant teratment significantly reduced acidity of silage compared with control. DM content of control silage was the lowest but DM loss of control silage was higher than that of additive treated silage. Ammonia-N content was the highest at formic acid treatment and level of Lactobacillus was decreased at control and formic acid treated silage. Total organic acid and lactic acid content of inoculant A and inoculant B were higher than those of other treated plots. The results of this study indicate that the treatment of LAB(Lactic acid bacteria) could be recommended as producing high quality of alfalfa silage.

• Korean Journal of Environmental Agriculture
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• v.22 no.2
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• pp.148-152
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• 2003

The phosphorus(P) adsorption capacities of various filter media were investigated in relation to the size and types of fitter media to screen the optimum condition. The objective of this study was to evaluate the constructed wetland longevity by improving P adsorption capacity. The maximum P adsorption capacities of filter media A($4{\sim}10\;mm$), B($2{\sim}4\;mm$) and C($0.1{\sim}2\;mm$) were 8, 10 and 22 mg/kg, respectively, showing those increased as the filter media size decreased. Among the experimental media, the optimum filter media size was $0.1{\sim}2\;mm$. When the filter Medium was supplemented with organic materials which were piled up and decayed in the constructed wetland, the P adsorption capacity was significantly enhanced Under the conditions of optimum fitter media size, the respective Maximum P adsorption capacities of filter media C when supplemented with Ca, Mg, Al and Fe were higher than that of filter media C. However the addition of Ca, Mg, Al and Fe to constructed wetland were not recommended because of the possibility of their secondary pollution. The maximum P adsorption capacity of filter media C was 22 mg/kg, but this was increased to 36 mg/kg when filter media C was supplemented with 2% oyster shell.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.765-773
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• 2000

The degradation of humic acid using $TiO_2$ coatings was studied, $TiO_2$ coatings were prepared by dip-coating method. Sol solutions for coating were prepared by mixing the gel, which can be produced by the reaction of $TiOCl_2$ and $NH_4OH$ solution, and hydrogen peroxide solution, and hydrolysis of titanium tetraisopropoxide (TTIP). It was shown from XRD that coatings from sol aged at $100^{\circ}C$ for 18h with titanium peroxo solution were crystallized to anatase in the range of temperatures of $25^{\circ}C$ to $500^{\circ}C$. In contrast, those coated from TTIP were crystallized to anatase at temperature above $400^{\circ}C$. So the sols originated from $TiCl_4$ can be applied for not only on the heat-resistance substrates but on the plastic substrates. Thickness and the quality of the films were dependent on the withdrawing speed, the concentration of sol, and the number of coating. The films showed various interference colors depending on the thickness of them. In the case that the films coated 2 times at withdrawing speed of 2.5cm per minute by 0.2M sol, the films had a transparent light blue color with thickness of around 50nm. It was known from the result of photo-degradation by $TiO_2$ coatings using humic acid that the removal efficiency of $COD_{cr}$ was over 85% after illumination of $UV/H_2O_2$ for 40min. and that of UV/VIS absorbable materials was over 95%.