• Microbiology and Biotechnology Letters
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• v.26 no.5
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• pp.465-469
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• 1998

The quantitative and rapid method for measuring the biodegradation of polymer materials in soil was developed. In this study, cellophane film was used as a model biodegradable polymer and the biodegradation was assayed by measuring the amount of glucose which was produced by a hydrolysis reaction using HCl after collecting the film from soil. Cellophane film was degraded 41.2% in 4 months during winter while it was degraded 76.5% in 2 months during summer. It means that biodegradation in soil is affected by environmental conditions. The biodegradation was also measured in an incubator (30$^{\circ}C$, humidity 50-55%) to exclude the environmental variations. Cellophane film was degraded 94% in that condition in 40 days. The biodegradation showed the first order kinetics and the rate constant was 0.067 (1/day). Acceleration of the biodegradation in soil was also studied. We added cultured soil microorganisms or nutrients such as N, P, and S into the soil. While the addition of microorganisms showed the temporary increase of rate constant, the addition of nutrients not only showed the increase of rate constant from 0.096 (1/day) to 0.21 (1/day) but also maintained the effect continuously.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.35-40
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• 2016

Recently, bacterial angular leaf spot disease, caused by Xanthomonas fragariae, causes severe damage in strawberry production and its' export to other countries, since the pathogen has been classified as an A2 quarantine pathogen. Typical the Angular Leaf Spot (ALS) disease represent that water-soaked angular spots symptoms, bacteria ooze exudate under relatively high humidity condition and later the spot become reddish brown on the leaf surface. The pathogen disseminated by irrigation water, infected mother plant and farmer's hand. In this study, we reported that rubbing inoculation method showed more effective in the pathogen dissemination than infiltration with needles, regardless the strawberry cultivars. Additionally, Dichloroisocyanurate (NaDCC) treatment in commercial strawberry fields provided reliable efficiency to reduce the bacterial angular leaf spot disease incidency and severity.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.20-26
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• 2010

Water soluble organic and inorganic species are important components in atmospheric aerosol particles and may act as cloud condensation nuclei to indirectly affect the climate. To characterize organic and elemental carbon(OC and EC), water-soluble organic carbon(WSOC) and inorganic ionic species contents, daily $PM_{2.5}$ measurements were made during the wintertime at an urban site of Gwangju. Average concentrations of WSOC, $NO_3^-$, $SO_4^{2-}$ and $NH_4^+$, which are major components in the water-soluble fraction in PM2.5, are 2.11, 5.73, 3.51 and $3.31{\mu}g/m^3$, respectively, representing 12.0(2.9~23.9%), 21.0(12.9~37.6%), 11.6(2.5~25.9%) and 11.7%(3.8~18.6%) of the $PM_{2.5}$, respectively. Abundance of water soluble organic compounds ranged from 5.4 to 35.9% of total water soluble organic and inorganic components with a mean of 17.6%. Even though the sampling was performed during the winter, the average contributions of secondary OC and WSOC, as deduced from primary OC/EC(or WSOC/EC) ratio, were relatively high, accounting for 17.9%(0~44.4%) of the total OC and 11.2%(0.0~51.4%) of the total WSOC, respectively. During the sampling period, low $SO_4^{2-}/(SO_4^{2-}+SO_2$) ratio of 0.14(0.03~0.32) and relative humidity condition in the winter time suggest an possibility of impact of long-range transport and/or aqueous transformation processes such as metal catalyzed oxidation of sulfur, in-cloud processes, etc.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.304-310
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• 2015

The moisture content of sawdust must be measured accurately and controlled appropriately during storage and transportation because biological degradation could be caused by improper moisture. In this study, to measure the moisture contents of Larix kaempferi sawdust, the near-infrared reflectance spectra (Wavelength 1000-2400 nm) of sawdust were used as detection parameter. After acquiring the NIR reflection spectrum of specimens which were humidified at each relative humidity condition ($25^{\circ}C$, RH 30~99%), moisture content prediction model was developed using mathematical preprocessings (e.g. smoothing, standard normal variate) and partial least squares (PLS) analysis with the acquired spectrum data. High reliability of the MC regression model with NIR spectroscopy was verified by cross validation test ($R^2$ = 0.94, RMSEP = 1.544). The results of this study show that NIR spectroscopy could be used as a convenient and accurate method for the nondestructive determination of moisture content of sawdust, which could lead to optimize wood utilization.

• Journal of the Korean Wood Science and Technology
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• v.38 no.4
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• pp.349-358
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• 2010

This study was carried out to investigate the optimum condition for sap exudation of Acer mono Max. tree in a site of Mt. Jiri, Hamyang-gun, Korea. Amount of sap exudation, air temperature, relative air humidity, tree diameter at breast height (DBH) and sugar content in sap were monitored during the early springtime, and correlation analysis of several factors was carried out to explain tree-to-tree and date-to-date variations in sap exudation. The correlation, linearlyassociated between DBH and sap amount, was strengthened as daily amount of sap increased, but there was no significant tree-to-tree variation in time and period for sap exudation. When amount of sap exudation was above 10 liter/day, the mean air-temperature was averaged at $1.2{\pm}1.6^{\circ}C$, the minimum at $-4.3{\pm}1.5^{\circ}C$ and the maximum at $11.8{\pm}1.9^{\circ}C$. The maximum air temperature and mean air temperature were significant (p < 0.05) factors for amount of sap in correlation analysis to explain date-to-date variation in sap exudation. Sucrose content in sap was in the range of 1.5 and 1.7% during exudation days, but sharply reduced to 0.6% level at the end of exudation period.

• Food Science and Preservation
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• v.5 no.3
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• pp.224-230
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• 1998

In order to establish proper storage conditions for ginger, the quality changes of gingers stored at three different temperatures(7$^{\circ}C$, 12$^{\circ}C$ and 20$^{\circ}C$) and three different relative humidities(75%, 85% and 95%RH) were investigated during 150 days of storage. Gingers stored at 7$^{\circ}C$ and 20$^{\circ}C$ showed rapid quality deterioration due to chilling injury and spouting respectively in any range of relative humidity. Ginger stored at 7$^{\circ}C$ was staled to show symptoms of the chilling injury such as moldiness, shrivelling, discoloration etc after 30 days of storage ; then it was deteriorated after 90 days of storage. Ginger stored at 20$^{\circ}C$ was completely lost its storage-life after 30 days of storage because of high sprouting ratio. However ginger stored at 12$^{\circ}C$, 75%RH showed better quality than ones stored at both 7$^{\circ}C$ and 20$^{\circ}C$, but it was not so good as the one at 7$^{\circ}C$, 95%RH. Consequently storage conditions of 12$^{\circ}C$, 95%RH was observed the best effecive condition for keeping rhizomes in good quality from weight loss, spouting, mouldiness and so on.

• Membrane Journal
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• v.18 no.4
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• pp.282-293
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• 2008

Partially sulfonated poly(aryl ether sulfone) membranes were prepared from the sulfonated sulfone monomer, which was synthesized by a nucleophilic substitution, non-sulfonated monomers and potassium carbonate by a direct polymerization method and a subsequent solution casting technique with mixed solvents of N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc). To investigate the effect of mixed solvent, the volume ratios of NMP and DMAc were varied in the range of $0{\sim}100%$ and the degrees of sulfonation of the copolymers were fixed as 50%. The surface properties of the resulting membranes were examined by scanning electron microscope (SEM) and atomic force microscope (AFM), and a comparative study of the morphology changes and the physicochemical properties such as proton conductivity and methanol permeability was achieved. It was found that proton conductivities depend on the volume ratio of NMP-DMAc mixed solvents, and the proton conductivity determined at the condition of $25^{\circ}C$ and 100% relative humidity was $1.38{\times}10^{-1}\;S/cm$ for the membrane prepared in the 50:50 v/v-% of NMP : DMAc mixed solvent.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.813-822
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• 2002

The purpose of the present study is first to refine the mathematical material models for moisture and temperature distributions in early-age concrete and then to incorporate those models into finite element procedure. The three dimensional finite element program developed in the present study can determine the degree of hydration, temperature and moisture distribution in hardening concrete. It is assumed that temperature and humidity fields are fully uncoupled and only the degree of hydration is coupled with two state variables. Mathematical formulation of degree of hydration Is based on the combination of three rate functions of reaction. The effect of moisture condition as well as temperature on the rate of reaction is considered in the degree of hydration model. In moisture transfer, diffusion coefficient is strongly dependent on the moisture content in pore system. Many existing models describe this phenomenon according to the composition of mixture, especially water to cement ratio, but do not consider the age dependency. Microstructure is changing with the hydration and thus transport coefficients at early ages are significantly higher because the pore structure in the cement matrix is more open. The moisture capacity and sink are derived from age-dependent desorption isotherm. Prediction of a moisture sink due to the hydration process, i.e. self-desiccation, is related to autogenous shrinkage, which may cause early-age cracking in high strength and high performance concrete. The realistic models and finite element program developed in this study provide fairly good results on the temperature and moisture distribution for early-age concrete and correlate very well with actual test data.

• The Journal of Sustainable Design and Educational Environment Research
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• v.16 no.3
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• pp.69-76
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• 2017

Indoor Air Quality(IAQ) affects physical and mental state of person who is residing indoor. Also, it manages daily life condition of Indoor Air in the building. According to the study, office workers spend 23 hours and 12 minutes, about 97% of his/her day indoor. Therefore, Indoor air quality affects not only the health of the person whose staying inside for a long hours but also the productivity and efficiency of work. This study conduct investigations on employees' awareness of indoor air quality of office in university. By doing so, we are able to determine current situation and provide basic data of improvement for derived problems. As a result, most of the respondents were not satisfied with ventilation and moisture which are elements of Indoor Air Quality. These led people to struggle with symptoms of health. Therefore, to improve the indoor air quality of a university office, it is necessary to exchange the air six times an hour according to recommendation of Refrigeration and Air Conditioning Engineers (ASHRAE)in the United States. Also, plan for Ventilation system that consider temperature, humidity and air flow indoor shall be provided for high quality conformability. furthermore, It is necessary to consider the multilateral in factors of generation of revenue through health care savings of workers and improvement of productivity.

• Journal of Periodontal and Implant Science
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• v.24 no.3
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• pp.661-670
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• 1994

It is well known that the application of dressings after periodontal surgery have benefits to provide the comforts to patient and to promote the healing process with action of bleeding control and temporary stabilization for the operated mobile teeth. But until recently the relationship between periodontal dressings and cells which are composed of periodontium has not been clear. The purpose of this study was to evaluate the cytotoxic effect of soluble extracts from the four different kinds of periodontal dressings, two of them were eugenol type (K.H.pack, Wondrpak) and the others were non-eugenol type (Coe-pak, Periocare), on the human gingival fibroblasts in vitro. Human gingival fibroblasts were primarily cultured from gingiva around third molar during the extraction for preventive purposes. Extracts solution were prepared with culture medium by means of imersing the consistent size of periodontal dressing made from plastic mold. Cell were inoculated into the 24 well plate with $3\;{\times}\;10^4\;cells/well$ of medium at $37\;^{\circ}C$, 100% of humidity, 5% of $CO_2$, incubator for 24 hours. After discard of the supernatant of medium, those cells were cultured with original, 1/2, 1/5, 1/10 diluted soluble extract for 24, 48 and 72 hours, and counted the number of cells using the hemocytometer at each designed time and concentration. Also, the cytotoxic effect of soluble extract was measured by Wataha's MTT assay method. In briefly, cells were inoculated and cultured into 96 well culture plate with $2\;{\times}\;10^4\;cells/well$ for 24 hours. Soluble extracts were applied to cultured cells and incubated for 48 hours at same condition. $50\;{\mu}l$ of MTT solution and DMSO were added into each well for the detection of absorbance with ELISA reader. The measured data were calculated by value of colorimetric assay for survival rate. The results were as follows ; In the case of eugenol type of dressing, original, 1/2 and 1/5 diluted extracts of K.H.pack showed very low survival rate. And original extract of Wondrpak showed strong cytotoxic effect and 1/2 diluted extract showed moderate cytotoxic effect. In the case of Non-eugenol type of dressings, only original extract of Coe-pak revealed strong cytotoxic effect and Periocare had little cytotoxic effect. It is concluded that eugenol type of dressings showed more cytotoxic effect than non-eugenol types. This study suggest that use of non-eugenol dressings after periodontal surgery is recommended.