간행물
한국환경과학회지 KCI 등재 Journal of Environmental Science International
- 발행기관 한국환경과학회
- 자료유형 학술지
- 간기 월간
- ISSN 1225-4517 (Print)2287-3503 (Online)
- 수록기간 1992 ~ 2023
- 주제분류 자연과학 > 자연과학일반 자연과학 분류의 다른 간행물
- 십진분류KDC 539DDC 628
권호리스트/논문검색
제26권 제9호 (2017년 9월) 10건
ORIGINAL ARTICLE
1.
2017.09
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In this study, the Chiu-2D velocity-flow rate distribution based on theoretical background of the entropy probability method was applied to actual ADCP measurement data of Gangjung Stream in Jeju from July 2011 to June 2015 to predict the parameter that take part in velocity distribution of the stream. In addition, surface velocity measured by SIV (Surface Image Velocimeter) was applied to the predicted parameter to calculate discharge. Calculated discharge was compared with observed discharge of ADCP observed during the same time to analyze propriety and applicability of depth of water velocity average conversion factor. To check applicability of the predicted stream parameter, surface velocity and discharge were calculated using SIV and compared with velocity and flow based on ADCP. Discharge calculated by applying velocity factor of SIV to the Chiu-2D velocity-flow rate distribution and discharge based on depth of water velocity average conversion factor of 0.85 were 0.7171 m3/sec and 0.5758 m3/sec, respectively. Their error rates compared to average ADCP discharge of 0.6664 m3/sec were respectively 7.63% and 13.64%. Discharge based on the Chiu-2D velocity-flow distribution showed lower error rate compared to discharge based on depth of water velocity average conversion factor of 0.85.
2.
2017.09
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Exposure to Diesel Particulate Matter (DPM) potentially causes adverse health effects (e.g. respiratory symptoms, lung cancer). Due to a lack of data on Elemental Carbon (EC) exposure levels in underground copper ore mining (unlike other underground mining industries such as non-metallic and coal mining), this case study aims to provide individual miners’ EC exposure levels, and information on their work practices including use of personal protective equipment. EC measurement was carried out during different work activities (i.e. drilling, driving a loader, plant fitting, plant operation, driving a Specialized Mining Vehicle (SMV)) as per NIOSH Method 5040. The copper miners were working 10 h/day and 5 days/week. This study found that the most significant exposures to EC were reported from driving a loader (range 0.02-0.42 mg/m3). Even though there were control systems (i.e. water tanks and DPM filters) on the diesel vehicles, around 49.5% of the results were over the adjusted recommendable exposure limit (0.078 mg/m3). This was probably due to: (1) driver’s frequently getting in and out of the diesel vehicles and opening the windows of the diesel vehicles, and (2) inappropriate maintenance of the diesel vehicles and the DPM control systems. The use of the P2 type respirator provided was less than 19.2%. However, there was no significant difference between the day shift results and the night shift results. In order to prevent or minimize exposure to EC in the copper ore mine, it is recommended that the miners are educated in the need to wear the appropriate respirator provided during their work shifts, and to maintain the diesel engine and emission control systems on a regular basis. Consideration should be given to a specific examination of the diesel vehicles’ air-conditioning filters and the air ventilation system to control excessive airborne contaminants in the underground copper mine.
3.
2017.09
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We studied the distribution of air temperature using the high density urban climate observation network data of Daegu. The observation system was established in February 2013. We used a total of 38 air temperature observation points (23 thermometers and 18 AWSs). From the distribution of monthly averaged air temperatures, air temperatures at the center of Daegu were higher than in the suburbs. The daily minimum air temperature was more than or equal to 25℃ and the daily maximum air temperature was more than or equal to 35℃ at the elementary school near the center of Daegu. Also, we compared the time elements, which are characterized by the diurnal variation of surface air temperature. The warming and cooling rates in rural areas were faster than in urban areas. This is mainly due to the difference in surface heat capacity. These results indicate the influence of urbanization on the formation of the daily minimum temperature in Daegu.
4.
2017.09
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Recently severe drought caused the water shortage around the western parts of Chungcheongnamdo province, South Korea. A Diversion tunnel from the Geum river to the Boryong dam, which is the water supply dam for these areas has been proposed to solve this problem. This study examined hydraulic impacts on the Geum river associated with the diversion plan assuming the severe drought condition of 2015 would persist for the simulation period of 2016. The hydraulic simulation model was verified using hydrologic and hydraulic data including hourly discharges of the Geum river and its 8 tributaries, fluctuation of tidal level at the mouth of the river, withdrawals and return flows and operation records of the Geum river barrage since Feb. 1, 2015 through May 31, 2015. For the upstream boundary condition of the Geum river predicted inflow series using the nonlinear regression equation for 2015 discharge data was used. In order to estimate the effects of uncertainty in inflow prediction to the results total four inflow series consisting of upper limit flow, expected flow, lower limit flow and instream flow were used to examine hydraulic impacts of the diversion plan. The simulation showed that in cases of upper limit and expected flows there would be no problem in taking water from the Geum river mouth with a minimum water surface level of EL(+) 1.44 m. Meanwhile, the simulation also showed that in cases of lower limit flow and instream flow there would be some problems not only in taking water for water supply from the mouth of the Geum river but also operating the diversion facility itself with minimum water surface levels of EL(+) 0.94, 0.72, 0.43, and 0.14 m for the lower limit flow without/with diversion and the instream flow without/with diversion, respectively.
5.
2017.09
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Characterization of spatio-temporal variations in PM2.5 in Gyeongnam (GN) province during 2015-2016 was investigated to assess the air quality in this area in terms of fine particles. Yearly mean concentrations of PM2.5 ranged from 19.1 to 29.5 μgm-3. High concentrations of PM2.5 were observed in spring (21.2-30.3 μgm-3) and winter (20.2-30.3 μgm-3). Low concentrations of PM2.5 were generally observed in fall (16.2-23.2 μgm-3). PM2.5 concentration was highest in the morning (10 AM). The fractions of PM2.5 in PM10 were 0.51-0.62 and two were significantly correlated (r=0.779-0.830), suggesting common sources (fossil fuel combustion, mobile sources, etc). CO was significantly correlated with PM2.5 in highly urbanized areas such as the city of Changwon (CW, r=0.711), compared to other air pollutants (SO2, NO2, and O3), suggesting dominance of industrial combustion sources.
6.
2017.09
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In order to investigate the effect of air temperature reduction on an urban neighborhood park, air temperature data from five inside locations (forest, pine tree, lawn, brick and pergola) depending on surface types and three outside locations (Suwon, Maetan and Kwonsun) depending on urban forms were collected during the summer 2016 and compared. The forest location had the lowest mean air temperature amongst all locations sampled, though the mean difference between this and the other four locations in the park was relatively small (0.2-0.5℃). In the daytime, the greatest mean difference between the forest location and the two locations exposed to direct beam solar radiation (brick and lawn) was 0.5-0.8℃ (Max. 1.6-2.1℃). In the nighttime, the mean difference between the forest location and the other four locations in the park was small, though differences between the forest location and locations with grass cover (pine tree and lawn) reached a maximum of 0.9-1.7℃. Comparing air temperature between sunny and shaded locations, the shaded locations showed a maximum of 1.5℃ lower temperature in the daytime and 0.7℃ higher in the nighttime. Comparing the air temperature of the forest location with those of the residential (Kwonsun) and apartment (Maetan) locations, the mean air temperature difference was 0.8-1.0℃, higher than those measured between the forest location and the other park locations. The temperatures measured in the forest location were mean 0.9-1.3℃ (Max. 2.0-3.9℃) lower in the daytime than for the residential and apartment locations and mean 0.4-1.0℃ (Max. 1.3-3.1℃) lower in the nighttime. During the hottest period of each month, the difference was greater than the mean monthly differences, with temperatures in the residential and apartment locations mean 1.0-1.6℃ higher than those measured in the forest location. The effect of air temperature reduction on sampling locations within the park and a relatively high thermal environment on the urban sampling locations was clearly evident in the daytime, and the shading effect of trees in the forest location must be most effective. In the nighttime, areas with a high sky view factor and surface types with high evapotranspiration potential (e.g. grass) showed the maximum air temperature reduction. In the urban areas outside the park, the low-rise building area, with a high sky view factor, showed high air temperature due to the effect of solar (shortwave) radiation during the daytime, while in the nighttime the area with high-rise buildings, and hence a low sky view factor, showed high air temperature due to the effect of terrestrial (longwave) radiation emitted by surrounding high-rise building surfaces. The effect of air temperature reduction on the park with a high thermal environment in the city was clearly evident in the daytime, and the shading effect of trees in the forest location must be most effective. In the nighttime, areas with high sky view factor and surface types (e.g., grass) with evapotranspiration effect showed maximum air temperature reduction. In the urban areas outside the park, the high sky view factor area (low-rise building area) showed high air temperature due to the effect of solar (shortwave) radiation during the daytime, but in the nighttime the low sky view factor area (high-rise building area) showed high air temperature due to the effect of terrestrial (longwave) radiation emitted surrounding high-rise building surfaces.
7.
2017.09
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Manufacturing and technology industries produce large amounts of air pollutants. Ulsan Metropolitan City, South Korea, is well-known for its large industrial complexes; in particular, the concentration of SO2 here is the highest in the country. We assessed SO2 monitoring sites based on conditional and joint entropy, because this is a common method for determining an optimal air monitoring network. Monthly SO2 concentrations from 12 air monitoring sites were collected, and the distribution of spatial locations was determined by kriging. Mean absolute error, Root Mean Squared Error (RMSE), bias and correlation coefficients were employed to evaluate the considered algorithms. An optimal air monitoring network for Ulsan was suggested based on the improvement of RMSE.
8.
2017.09
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The present study was conducted for the purpose of analyzing the growth response of Dracaena braunii treated with chloride ions and to evaluate its salt tolerance. Distilled water (CON) was spiked with 1 (C1), 2 (C2), 5 (C5), 10 (C10) and 15 g/L (C15) CaCl2, respectively. Acidity (pH) and electrical conductivity of hydroponic solution, and leaf width, leaf length, root length, number of leaves, fresh weight, dry weight and the water content of Dracaena braunii were measured. Acidity and electrical conductivity remarkably increased commensurate with increasing concentrations of CaCl2. Growth in the C1 treatment was better than that in CON, whereas the C10 or C15 treatments caused either slow growth or withering of the plants. Fresh weight, dry weight and water content were significantly decreased in response to CaCl2 concentration, compared with those in the control. These results showed that CaCl2 concentration less than 1 g/L may be used as a hydroponic solution for D. braunii, as long as the water quality is not too saline. The chlorine ion has a negative effect on the growth.
9.
2017.09
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Emergy methodology was used to analyze the biophysical basis of Korean agriculture and assess its sustainablility. Total yearly emergy input into Korean agriculture was 7.72×10²² sej/yr in 2013. Purchased inputs were the dominant emergy source, accounting for 90.1% (6.95×10²² sej/yr) of the annual input. This clearly indicates that the Korean agriculture is a modern, industrialized system that depends mostly on market goods and services derived from nonrenewable resources. The monetary equivalent of the total emergy input was 18.9 trillion ₩/yr, 1.5 times greater than the total production cost from farm expense surveys. Emergy return on investment of Korean agriculture was low, with an emergy yield ratio of 1.11. Korean agriculture appears to exert pressure on the environment as revealed by the high environmental loading ratio of 9.30. With very low emergy input from renewable sources (9.7%) and high environmental pressure, Korean agriculture is not sustainable, with an emergy sustainability index of 0.12. This study suggests that higher use efficiency of and lower dependence on nonrenewable purchased inputs need to be prioritized in an effort to enhance the sustainability of Korean agriculture.
TECHNICAL NOTE
10.
2017.09
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In this study, we analyze changes in soil heat flux and air temperature in August (summer) and January (winter) according to net radiation, at a mud flat in Hampyeong Bay. Net radiation was observed as -84.2~696.2 W/m2 in August and -79.4~352.5 W/m2 in January. Soil heat flux was observed as -80.7~139.5 Wm-2 in August and -49.09~137 W/m2 in January. Air temperature was observed as 24.2~32.9˚C in August and -1.5~11.1˚C in January. The rate of soil heat flux for net radiation (HG/RN) was 0.17 in August and 0.34 in January. Because the seasonal fluctuation in net radiation was bigger than the soil heat flux, net radiation in August was bigger than in January. We estimated a linear regression function to analyze variations in soil heat flux and air temperature by net radiation. The linear regression function and coefficient of determination for the soil heat flux by net radiation was y=0.19x-7.94, 0.51 in August, and y=0.39x-11.69, 0.81 in January. The time lag of the soil heat flux by net radiation was estimated to be within ten minutes in August 2012 and January 2013. The time lag of air temperature by net radiation was estimated at 160 minutes in August, and 190 minutes in January.
