• Korean Journal of Soil Science and Fertilizer
• /
• v.43 no.3
• /
• pp.363-373
• /
• 2010

"Curve number" (CN) indicates the runoff potential of an area. The US Soil Conservation Service (SCS)'s CN method is a simple, widely used, and efficient method for estimating the runoff from a rainfall event in a particular area, especially in ungauged basins. The use of soil maps requested from end-users was dominant up to about 80% of total use for estimating CN based rainfall-runoff. This study introduce the use of soil maps with respect to hydrologic and watershed management focused on hydrologic soil group and a case study resulted in assessing effective rainfall and runoff hydrograph based on SCS-CN method in a small watershed. The ratio of distribution areas for hydrologic soil group based on detailed soil map (1:25,000) of Korea were 42.2% (A), 29.4% (B), 18.5% (C), and 9.9% (D) for HSG 1995, and 35.1% (A), 15.7% (B), 5.5% (C), and 43.7% (D) for HSG 2006, respectively. The ratio of D group in HSG 2006 accounted for 43.7% of the total and 34.1% reclassified from A, B, and C groups of HSG 1995. Similarity between HSG 1995 and 2006 was about 55%. Our study area was located in Sosu-myeon, Goesan-gun including an approx. 44 $km^2$-catchment, Chungchungbuk-do. We used a digital elevation model (DEM) to delineate the catchments. The soils were classified into 4 hydrologic soil groups on the basis of measured infiltration rate and a model of the representative soils of the study area reported by Jung et al. 2006. Digital soil maps (1:5,000) were used for classifying hydrologic soil groups on the basis of soil series unit. Using high resolution satellite images, we delineated the boundary of each field or other parcel on computer screen, then surveyed the land use and cover in each. We calculated CN for each and used those data and a land use and cover map and a hydrologic soil map to estimate runoff. CN values, which are ranged from 0 (no runoff) to 100 (all precipitation runs off), of the catchment were 73 by HSG 1995 and 79 by HSG 2006, respectively. Each runoff response, peak runoff and time-to-peak, was examined using the SCS triangular synthetic unit hydrograph, and the results of HSG 2006 showed better agreement with the field observed data than those with use of HSG 1995.

• The Journal of Society for e-Business Studies
• /
• v.25 no.1
• /
• pp.135-176
• /
• 2020

This study is to investigate the factors affecting the usage intentions of 5G service between 5G service subscribers and non-subscribers based on the Integratively Extended Technology Acceptance Model in the initial B2C 5G service market. We designed the integratively extended technology acceptance model to find the more specific factors to affect the usage intentions by integrating the exogenous factors including the technical factors, the social factors, and the personal factors with the ETAM(Extended Technology Acceptance Model). Referring to the previous studies, we constructed the hypotheses of structural influence relationship from the exogenous factors to the dependent usage intentions factors through the mediating belief factors. We designed the 5G service usage intentions model based on these hypotheses and operational definitions of the factors. Using the analysis of SEM(Structural Equation Model), the proposed model and the hypotheses were empirically tested by the data collected from 245 subscribed respondents and 245 non-subscribed respondents. As a result, the perceived ease of use has an effect on the perceived usefulness and enjoyment, and the perceived usefulness/enjoyment and the personal innovativeness have positive effects on the usage intentions of both groups.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.26 no.1
• /
• pp.38-47
• /
• 2016

Objectives: The objective of this study was to determine the exposure levels of forklift operators to diesel engine exhaust(DEE) using black carbon(BC), elemental carbon(EC), and nitrogen dioxide($NO_2$) as indicators. Methods: A total of eight forklift operators in six collection companies were assessed over a period of two months from July to September 2015. BC was measured using a real-time monitor and respirable EC samples were analyzed using the NIOSH method 5040. $NO_2$ samples were collected using a passive badge-type sampler. Results: The geometric mean of BC, EC and $NO_2$ were $3.1-19.1{\mu}g/m^3$, $2.1-23.8{\mu}g/m^3$, and 12.5-166.6 ppb at all companies. When forklifts were operating both outside and inside, BC concentrations increased 2.0-5.6 times. The highest increase was observed when forklifts were operating indoors. The increase in BC concentrations varied by company(company A: 2.0 times, B: 3.2 times, C: 5.6 times, D: 2.1 times, E: 5.1 times, F: 2.6 times). The geometric mean of BC, EC, and $NO_2$ for the forklift operators was $9.6{\mu}g/m^3$, $7.9{\mu}g/m^3$, and 48.9 ppb, respectively. The geometric mean of BC, EC, and $NO_2$ for manufacturing workers was $9.3{\mu}g/m^3$, $0.9{\mu}g/m^3$, and 85.2 ppb, respectively. The mean BC and EC exposure levels for the forklift operators were slightly higher than those for manufacturing workers, but $NO_2$ levels for manufacturing workers were higher than those for the forklift operators(p>0.05). Multiple regression analysis revealed that diesel exhaust emissions standard, forklift weight and forklift manufacturer were the most influential factors in determining worker exposure. Conclusions: In the DEE work environment, workers who perform tasks within the workplace as well as inside forklifts as operators are likely to be exposed to a lack of ventilation. Further study of forklift operators' exposure to DEE indicators should be conducted to include a wider range of occupational and environmental situations, such as collection procedures, seasonal situations, types of fuel used, and number of forklifts.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.9
• /
• pp.1476-1485
• /
• 2004

Of solvent-extracts prepared from the 90 kinds of Korean traditional tea and rice gruel plants, cold-water extract from peels of Citrus unshiu (CUI-0) showed the most potent intestinal immune system modulating activity through Peyer’s patch whereas other extracts did not have the activity except for cold-water extracts of Laminaria japonica, Polygonatum japonicum, Poncirus trifoliata, and hot-water extracts of Gardenia jasminoides, Lycium chinense having intermediate activity. CUI-0 was further fractionated into MeOH-soluble fraction (CUI-1), MeOH insoluble and EtOH-soluble fraction (CUI-2), and crude polysaccharide fraction (CUI-3). Among these fractions, CUI-3 showed the most potent stimulating activity for the proliferation of bone marrow cells mediated by Peyer’s patch cells, and contained arabinose, galacturonic acid, galactose, glucose, glucuronic acid and rhamnose (molar ratio; 1.00:0.53:0.45:0.28:0.28:0.19) as the major sugars, and a small quantity of protein (9.4%). In treatments of CUI-3 with pronase and periodate (NaIO₄), the intestinal immune system modulating activity of CUI-3 was significantly reduced, and the activity of CUI-3 was affected by periodate oxidation particularly. The potently active carbohydrate-rich fraction, CUI-3IIb-3-2 was further purified by anion-exchange chromatography on DEAE-Sepharose FF, Sepharose CL-6B and Sephacryl S-200. CUI-3IIb-3-2 was eluted as a single peak on HPLC and its molecular weight was estimated to be 18,000 Da. CUI-3IIb-3-2 was consisted mainly of arabinose, galactose, rhamnose, galacturonic acid and glucuronic acid (molar ratio;1.00:0.54:0.28:1.45:0.63) in addition to a small amount of proteins (3.2%). In addition, CUI-3IIb-3-2 showed the activity only through Peyer’s patch cells, but this fraction did not directly stimulate proliferation of bone marrow cells. It may be concluded that intestinal immune system modulating activity of peels from C. unshiu is caused by pectic polysaccharides having a polygalacturonan moiety with neutral sugars such as arabinose and galactose.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.42 no.10
• /
• pp.1682-1689
• /
• 2013

The objective of the present study is to elucidate the physicochemical and microbial properties of Korean traditional rice wine, Makgeolli, supplemented with mulberry during the fermentation process. Four hundred grams of mulberries (20% of the total amount of rice) were ground and incorporated into the rice solution (3.5 L of distilled water, 2.0 kg of rice, 28.0 g of yeast, and 80.0 g of nuruk). The rice solution was then placed in a water bath set at $28^{\circ}C$ and left to ferment for 7 days. The alcohol contents between the control and mulberry Makgeolli were not significantly different. The pH values of the control and mulberry Makgeolli decreased and the total acidity values were elevated after a 7-day fermentation. In the microbial analysis, the total viable cell count, lactic acid bacteria count and yeast count increased considerably through the 7-day fermentation process. For all the samples, the glucose and succinic acid contents were highest among all free sugars and organic acids, respectively. Forty-eight different volatile compounds were found in all the samples after the 7-day fermentation process.

• Korean Journal of Health Education and Promotion
• /
• v.12 no.2
• /
• pp.48-61
• /
• 1995

This study attempted to analyze the health habits affecting health status of industrial workers. Data was collected from 57 industries of 900 workers at Inchon. The research has been carried out through self-administered questionnaire and from the analysis of the health examination records and the results were as follows: 1. Among 861 respondents, men were 81.2%, women were 18.8%, 42, 6% were of the 30-40 age group, the married were 65.7%, the single were 32.5%, the high school graduates were 62.4% and 37.3% were of people who worked between 1 and 5 years. 2. As far as the seven health habits, current smokers were 54.9%, people who regularly exercise was 31.7%, 7-8 hour of sleep, on the average were 74.0%, people eating breakfast nearly every day were 8.0%, and people eating between meals almost every day were 54.2%. Heavy drinkers who drink 3-4 times or more per week were 13.2%, 1-2 times per week were 26.8% and the obese were 4.6%, 3. Health status of A and B, estimated by doctors in the health examination were 81.7% and C, D1, D2, the unhealthy were 18.3%. Men were reported more than women in unhealthy groups and the results regarding health status reflect gender, educational level and age, That is to say that, lower educational level group and over 30 years of age group perceive their health to be worse than the higher educational level and under 30 age group, And these differences were statistically significant. 4. The relationship between health habits and health status, expressed in terms of the odds ratio. Current smokers had a consistently worse health status than a nonsmokers with a 1.36 odds ratio. The workers who reported eating breakfast rarely or never were more associated with the unhealthy group than the regular breakfast eating group with a 2.48 odds ratio. One or more drink per week had a worse health status than a never or a little drinker with a 1.42 odds ratio. 5, The Health habits score and duration of work were selected as significant factors influencing health status based on logistic analysis. According to the results of this model, the odds ratio of good health status was 2.06 for good health habit score, 1.55 for population who worked seven years or more duration of work. As we have seen, good practices were found to be associated with better health and the effect of the health habits was cummulative;those who followed 6-7 health habits were in better health, even though they were older than those who failed to do so. Therefore, in order to provide the health promotion of workers it is necessary to establish a health management plan for an effective health education and health service. If we use this type of study as a prospective study design, we can get a precise basic data for health promotion and a management plan for industrial workers.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.2
• /
• pp.103-109
• /
• 2009

Soils originated from limestone, located at the southern part of Kangwon province and Jecheon, Danyang of Chungbuk province are mainly composed of fine texture, and have different properties from soils originated from granite and granite gneiss, especially for water movement. This study was conducted for classification of hydrologic soil group (HSG) of soils originated from limestone by measuring the infiltration rate of surface soils and percolation rate of sub soils. Soils used for the experiment were 6 soils in total : Gwarim, Mosan, Jangseong, Maji, Anmi and Pyongan series. Infiltration and percolation rate were measured by a disc tension infiltrometer and a Guelph permeameter, respectively. Particle size distribution and organic matter content of the soils were analyzed. HSG, which was made by USDA NRCS(National Resources Conservation Service) for hydrology, of Gwarim series with O horizon of accumulated organic matter was classified as type A which show the properties of low runoff potential, rapid infiltration and percolation rate. HSG of Mosan series, which has high gravel content and very rapid permeability, was classified as type B/D because of the impermaeble base rock layer under 50cm from surface. HSG of Jangseong series with shallow soil depth was classified as type C/D owing to the impermaeble base rock layer under 50cm from surface. HSG of Maji series was type B, and HSG of Anmi series used as paddy land was type D because of slow infiltration and percolation rate caused by the disturbance of surface soil by puddling. HSG of Pyeongan series having a sudden change of layer in soil texture was type D because of the slow percolation rate caused a the layer.

• Journal of Korean Society of Forest Science
• /
• v.77 no.1
• /
• pp.32-42
• /
• 1988

This research was to establish the fundamental materials for the preservation and multiple-purpose management of forest vegetation of Dong Hwa Sa area located in the south facing slope of Mt. Pal-Gong. Analysis of forest vegetation of this area was studied by the method of Gentaro Toyohara, based on ZM School method and Pfister. The results obtained were summarized as follows. (1). Forest vegetation in this area divided into mountain forest and valley forest. (2). Mountain forest divided into A. Pinus densiflora community, B. Carpirtus laxiflora community, C. Quercus mongolica community. (3). Valley forest was formed mostly of Zelkova serrata community. (4). Piraus densiflora community divided into 1. Pines densiflora typical group, 2. Pines densiflora-Alnus hirsuta group, 3. Pines densiflora-Ilex macropoda group. (5). Quercus mongolica community divided into 1. Pinus densiflora-Carpinus cordata group, 2. Prunus sargentii-Hydrangea serrata for. acuminata group, (6). Zelkova serrata community divided into 1. Acer mono group, 2. Vine plant group. A vegetation analysis based on concepts and methods developed by Robert, D. Pfister and Gentaro Toyohara was considered to be effective on providing a guiding principle for a multiple-purpose management of forestry and a three-dimensional utilization of forest, but it is not easy for us to utilize such a analysis method because we are not rich in the materials of analysis of vegetation to our forest. Thus, It is necessary that we should collect much materials to various parts of forest in order that may utilize this method of analysis of vegetation.

• Korean Journal of Food Science and Technology
• /
• v.45 no.2
• /
• pp.227-234
• /
• 2013

The purpose of this study was to determine the possibility of using Oenanthe javanica as a natural health food source. To accomplish this, its general and biological activities were measured. Its carbohydrate, crude protein, crude lipid, and ash contents were 44.7, 9.8, 8.9, and 27.8%, respectively. The K content was largest for minerals followed by Ca, P, and Mg, which means that Oenanthe javanica is an alkali material. The concentrations of total phenol and flavonoids of OJE were $88.9{\pm}0.46$ mg GAE/g, and $28.6{\pm}0.64$ mg QE/g, respectively. Gallic acid, catechin, chlorogenic acid, and caffeic acid in OJE as measured by using HPLC were $0.9{\pm}0.23$, $1.2{\pm}0.19$, $227.1{\pm}0.62$, and $4.0{\pm}0.35$ mg/g. The DPPH and ABTS radical scavenging activities of OJE were 72.2%, and 66.1%, respectively, at $1,000{\mu}g/mL$. The FRAP and reducing power of OJE were 0.79, and 0.41 absorbance units value respectively, at $1,000{\mu}g/mL$. OJE possessed significant antioxidant properties, which suggests its great potential as a functional ingredient for food applications.

• International Journal of Highway Engineering
• /
• v.15 no.4
• /
• pp.85-94
• /
• 2013

PURPOSES: The performance of tack coat, commonly used for layer interface bonding, is affected by application rate and curing time. In this study, bonding strength tests were performed according to the application rate and curing time of asphalt emulsion. Based on finding from this study, optimum application rates and curing times are proposed. METHODS: In order to investigate bonding characteristic of asphalt emulsion, tests were performed on both asphalt concrete pavement and portland concrete pavement. Also, asphalt emulsions were tested at the application rate of 0, 0.2, 0.4, 0.6, and $0.8{\ell}/m^2$ and at the curing time of 0, 0.5, 1, 2, and 24 hours. Pull-off test and shear bonding strength test, which commonly used for bonding strength measurement of asphalt emulsion, were adopted for this study. To assess field performance under different testing condition, asphalt emulsions were applied to in-service pavement. Throughout coefficient of determination analysis between material index properties from asphalt emulsion and mechanical response from bonding strength tests, performance correlativity was analyzed. RESULTS: Test results show that optimum application rate for asphalt overlay on asphalt concrete pavement (AOA) and asphalt overlay on concrete pavement (AOC) was $0.4{\sim}0.5{\ell}/m^2$ and $0.3{\sim}0.5{\ell}/m^2$, respectively. According to the curing time increment, tensile strength and shear strength of AOC were increased to 22~44% and 20~39%, respectively. AOA case also show strength increment in tensile strength (42%) and shear strength (9%). We tested the applicability of tack coat materials at the field sites, and our findings demonstrated that the bonding (for D and E) and rapid curing (for B, C, and D, E) performances were superior than others. Among material index properties, there was a high correlation between penetration ratio and bonding strength test result. CONCLUSIONS : Result show that interlayer bonding strength was affected by asphalt emulsion type, application rate and curing time. AOC required slightly higher application ($0.1{\ell}/m^2$) than AOA. Both AOA and AOC cases show higher strength at longer curing time. Up to 2hours of curing, rapid strength increments were observed, but strength increment ratio was decreased after 2hours of curing. From the observed correlation between penetration ratio and bonding strength, it is expected that penetration ratio can be used as one of important factors affecting bonding strength analysis.