• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.318-324
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• 2010

In this study, commercial pellet type sorbents for the collection of $CO_2$ from a local municipal waste incinerator were prepared and characterized in terms of adsorption efficiency by varying the operating conditions of a field process. The concentration of $CO_2$ in the flue gas ranged from 8 to 10%, which entered the test packed bed. As a result of this experiment, the sorbent procured from A-company, which is mainly composed of calcium compounds, showed the highest adsorption efficiency. The regeneration efficiency was fairly low, however. It also was found that based on adsorption breakthrough time, the relatively low flow rate of 10 LPM into the bed allowed higher collection efficiency. The higher flow rate of 40 LPM, on the other hand, tended to decrease the retention of the adsorption.

• Journal of the Korean Wood Science and Technology
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• v.52 no.1
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• pp.47-57
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• 2024

Solar energy is one of the most promising options for renewable energy and biomass is one of them. One of the main biomass sources, sugarcane bagasse, is produced annually in more than hundreds of nations worldwide exceeding 4.25 billion tons. To dry a 900-mm deep fixed bed of wet sugarcane bagasse, a solar air heater with a collector area of 2 m² was installed. Between October 10^th to 19^th in Gwangju, South Korea, a 9-day drying period, the solar collector received a total of 496,145 kJ of solar radiation. During this time, 54.5 kg of water was extracted from 133 kg of wet sugarcane bagasse (average green moisture content of 47.6%_w.b.). The estimated net heat from the evaporation of water removed during the dying period accounted for approximately 27% of the total solar radiation on the solar collector.

• Journal of Korean society of Dental Hygiene
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• v.12 no.1
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• pp.1-15
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• 2012

Objectives : The purpose of this study was to examine the effect between job stress in jobholders and xerostomia. Methods : 250 jobholders living in Jecheon city were the subjects of this questionnaire. The questionnaire was made up of three contents and 37 items: general characteristic(13), job stress(14), degree & behavior of xerostomia(10). The data were analyzed by two-sample t-test, one-way ANOVA to examine the subjects general characteristics, job stress and degree of xerostomia and were analyzed by Chi-square test to examine the subjects general characteristics, job stress and behavior of xerostomia. Results : Only 215 jobholders were evaluated due to inadequate responses. The results were as follow. 1. As general characteristic of jobholder, male(83.7%) were more than women(16.3%), 30~39 year-old(47%) in age variable, university graduation(63.7%) in the last educational background variable, 2~3 million won(31.2%) in the month average income variable, 1~5 year(33.5%) in tour of duty variable, non-smoker(47.9%) in smoking variable were most. Married(58.6%) were more than unmarried(39.5%). Alcoholic(69.8%) were more than non-alcoholic(30.2%). 2. As classification of job stress, high strain group was 28.4%, active group was 26%, low strain group was 24.2%, passive group was 21.4%. 3. Analysis of effect between general characteristic and degree & behavior of xerostomia showed smoker were statistical significantly higher than non-smoker on 'dry eat', 'Am-sal', 'Night awake', 'Slip-liq'and 'Gumcandy'(p<0.05) and showed alcoholic were statistical significantly higher than non-alcoholic on 'Dry PM', 'Night awake, $H_2O$-bed'(p<0.05). 4. Analysis of effect between job stress and degree & behavior of xerostomia showed hight strain group were statistical significantly higher than low strain group on 'Dry PM', 'Dry-day', 'Am-sal', 'Eff-life'and 'Night awake'(p<0.05). Conclusions : As high strain group were higher than other groups on degree & behavior of xerostomia, stress would be factor that have an effect on xerostomia. Thus consider and management of stress is necessary for diagnosis and treatment of xerostomia.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.100-108
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• 1988

This research was performed to estimate the influence of relative light intensity, planting density, growth period on the growth of fresh and dry weight of the stem and branches, and root in the pretreatment transplanting bed. 1. The growth of fresh and dry weight of the stem and branches per seedling varied in the order of 63%>100%>37%>19% in relative light intensity, and increased with decrease of planting density, and grew highly during the period from May to June. The contribution rates to the growth of fresh and dry weight of the stem and branches were 49.4% and 39.6% in shading treatment, and 4.3% and 6.4% in planting density, and 34.2% in growth period respectively. Of the three factors, that is, shading, density and period, all of the interactions between two factors, and among the three factors in the growth of fresh and dry weight of stem and branches were significant. The growth of fresh and dry weight of root per seedling increased with light intensity and decreased with increase of density. The best growth of root, showed during the period from May to June in fresh weight, but during the period from July and August in dry weight of root. For the three factors, that is, shading, density and growth period, all the interactions between any two factors, and among the three factors in the growth of fresh and dry weight of root were significant.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.25-31
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• 2018

In this study, the Controlled Low Strength Material (CLSM) was investigated to utilize the bottom ash and fly ash generated in the Circulating Fluidized Bed Combustor (CFBC). It was confirmed that the CFBC fly ash (CFBC-F) and CFBC bottom ash (CFBC-B) had an irregular particle shape through SEM measurement. According to the results of the hazard analysis, it was also confirmed that they were environmentally safe. In the case of mixing with CFBC-F, the unit quantity was increased. Regarding the rate of change of length, shrinkage in the range of -0.05~0.50% occurred in the air dry curing condition and expansion in the range of 0.1~0.6% in the sealed curing condition. Compressive strength was increased in the sealed curing condition compared to the air dry curing condition because there was enough moisture for hydration reaction in the long term. Therefore, the results of this study are likely be used as basic research data of mine filler materials.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.405-410
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• 1996

To elucidate the pattern of nutrient absorption and endosperm consumption as the seedling age of rice, Dongjinbyeo was raised in the seedling box with different nitrogen levels. Absorption of nitrogen and phosphorus were high in the order of artificial seed bed soil, sand with N-1g /box and sand without N from 3 and 5 days after seeding but, potassium wasn't significantly different between sand＋N-1g /box and sand. Endosperm consumption rate was high in the order of artificial seed bed soil, sand ＋ N-1g /box and sand but, endosperm dependence rate (endosperm consumption /top dry weight) was vice versa. Seedling height and dry weight were higher in the order of artificial seed bed soil, sand+N-1g /box and sand from 3 days after seeding, number of leaves were more from 5 days after seeding in same order.

• Journal of Environmental Science International
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• v.15 no.6
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• pp.513-525
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• 2006

In recent decades, biofiltration has been widely accepted for the treatment of contaminated air stream containing low concentration of odorous compounds or volatile organic compounds (VOCs). In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various amounts of pulverized activated carbon (PAC) were synthesized for the biofilter media and tested for toluene removal. Four biofilter columns were operated for 60 days to remove gaseous toluene from a contaminated air stream. During the biofiltration experiment, inlet toluene concentration was in the range of 0-150 ppm and EBRT (i.e., empty bed residence time) was kept at 26-42 seconds. Pressure drop of the biofilter bed was less than 3 mm $H_2O/m$ filter bed. The maximum removal capacity of toluene in the biofilters packed with PU-PAC foam was in the order of column II (PAC=7.08%) > column III (PAC=8.97%) > column I (PAC=4.95%) > column IV (PAC=13.52%), while the complete removal capacity was in the order of column II > column I > column III > column IV. The better biofiltration performance in column II was attributed to higher porosity providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-PAC foam with 7.08% of PAC content had higher maximum removal rate ($V_m$=14.99 g toluene/kg dry material/day) than the other PU-PAC foams. In overall, the performance of biofiltration might be affected by the structure and physicochemical properties of PU foam induced by PAC content.

• Journal of Korea Water Resources Association
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• v.44 no.2
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• pp.145-156
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• 2011

Two dimensional numerical model of high-order accuracy is developed to analyze complex flow including transition flow, discontinuous flow, and wave propagation to dry bed emerging at natural river flow. The bed slope term of two dimensional shallow water equation consisting of integral conservation law is treated efficiently by applying quasi-steady wave propagation scheme. In order to apply Finite Volume Method using Fractional Step Method, MUSCL scheme is applied based on HLL Riemann solver, which is second-order accurate in time and space. The TVD method is applied to prevent numerical oscillations in the second-order accurate scheme. The developed model is verified by comparing observed data of two dimenstional levee breach experiment and dam breach experiment containing structure at lower section of channel. Also effect of the source term is verified by applying to dam breach experiment considering the adverse slope channel.

• Environmental Engineering Research
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• v.10 no.4
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• pp.191-198
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• 2005

A novel technology for the removal of nitrogen from wastewater, an autotrophic denitrification process with sulfur particles, has been developed. A respirometer was employed to monitor the nitrogen gas produced in the reactor, while 4',6-diamidino-2-phenylindole staining was employed to investigate the biomass distribution in terms of cell number according to the reactor height. From the respirometric monitoring, the denitrification reaction was defined as a first order reaction. The reactor was divided into 7 sections and biomass was analyzed in each section where cell number was ranged from $4.8\;{\times}\;10^6\;to\;8.7\;{\times}\;10^7$ cells/g dry weight of sulfur. Cells placed mostly in the lower layer ( < 10 cm of height). A function for biomass distribution was obtained with non-linear regression. Then a mathematical model has been developed by combining a plug-flow model with the biomass distribution function. The model could make a vertical profile of the up-flow packed-bed reactor resulting in a reasonable comparison with measured nitrate concentration with 5% of error range.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.176-183
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• 2010

Endosulfan degrading ability of Klebsiella oxytoca KE-8 immobilized by entrapment with activated carbon was examined. Endosulfan degradation by the immobilized bacterial strains on several different activated carbon based support materials was investigated. Based on results, activated carbon ($8\times30$ mesh) was chosen as a support material. The immobilized Klebsiella oxytoca KE-8 with the cell density of 4 mg $g^{-1}$ (dry weight) degraded 22.18 ug $ml^{-1}$ endosulfan within 5 days at pH 7.0, $30^{\circ}C$ in batch shake flask cultures. Also, we an experimented recycle packed bed column mode and continuous packed bed column mode for endosulfan degradation. Under optimum operation condition, the immobilized cells in a laboratory scale pack bed column with support beads were able to degrade endosulfan completely in defined minimal salt medium at a maximum rate of 129.6 ug $ml^{-1}$ per day. Moreover, the endosulfan degradation activity could be demonstrated at $4^{\circ}C$ for one month without significant decrease in activity. Results of this study suggest that immobilized cells of Klebsiella oxytoca KE-8 might be applicable to endosulfan contaminated site.