• Journal of Environmental Science International
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• v.26 no.10
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• pp.1167-1180
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• 2017

Numerical Weather Prediction (NWP) models such as the Weather Research and Forecasting (WRF) model are essential for forecasting one-day-ahead solar irradiance. In order to evaluate the performance of the WRF in forecasting solar irradiance over the Korean Peninsula, we compared WRF prediction data from 2008 to 2010 corresponding to weather observation data (OBS) from the Korean Meteorological Administration (KMA). The WRF model showed poor performance at polluted regions such as Seoul and Suwon where the relative Root Mean Square Error (rRMSE) is over 30%. Predictions by the WRF model alone had a large amount of potential error because of the lack of actual aerosol radiative feedbacks. For the purpose of reducing this error induced by atmospheric particles, i.e., aerosols, the WRF model was coupled with the Community Multiscale Air Quality (CMAQ) model. The coupled system makes it possible to estimate the radiative feedbacks of aerosols on the solar irradiance. As a result, the solar irradiance estimated by the coupled system showed a strong dependence on both the aerosol spatial distributions and the associated optical properties. In the NF (No Feedback) case, which refers to the WRF-only stimulated system without aerosol feedbacks, the GHI was overestimated by $50-200W\;m^{-2}$ compared with OBS derived values at each site. In the YF (Yes Feedback) case, in contrast, which refers to the WRF-CMAQ two-way coupled system, the rRMSE was significantly improved by 3.1-3.7% at Suwon and Seoul where the Particulate Matter (PM) concentrations, specifically, those related to the $PM_{10}$ size fraction, were over $100{\mu}g\;m^{-3}$. Thus, the coupled system showed promise for acquiring more accurate solar irradiance forecasts.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.231-243
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• 2015

Four different paddy soils collected around the Gyeongju nuclear site were treated with $^{99}TcO_4{^-}$ solution under the assumption of two contrasting contamination scenarios. Scenario I (SN-I) is for a pre-transplanting deposition of $^{99}Tc$ followed by plowing, whereas SN-II is for its deposition onto the water surface shortly after transplanting. Rice plants were grown in lysimeters in a greenhouse. Plant uptake of $^{99}Tc$ was quantified with the $TF_{area}$ ($m^2{\cdot}kg^{-1}-dry$). The SN-II $TF_{area}$ values for straws and brown rice, having been generally higher than the SN-I values, were within the ranges of $6.9{\times}10^{-3}{\sim}4.1{\times}10^{-2}$ and $5.2{\times}10^{-6}{\sim}7.3{\times}10^{-5}$, respectively. Sorption onto clay seems to have decreased $^{99}Tc$ uptake in SN-I, whereas it may have had an insignificant effect in SN-II. A phenomenon characteristic of submerged paddy soil, i.e., the development of a thin oxic surface layer may have greatly affected the rice uptake of SN-II $^{99}Tc$. The surface-water concentrations of $^{99}Tc$ were much higher in SN-II than in SN-I. For the percolating water, however, the opposite was generally true. At most 1.3% of the applied $^{99}Tc$ were leached through such percolation. The use of empirical deposition time-dependent $TF_{area}$ values was considered desirable in assessing the radiological impact of a growing-season deposition of $^{99}Tc$ onto paddy fields.

• Korean Journal of Materials Research
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• v.31 no.10
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• pp.552-561
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• 2021

For the purpose of manufacturing a high efficiency TiO₂ photocatalyst, B-doped TiO₂ photocatalysts are synthesized using a plasma electrolytic oxidation method in 0.5 M H₂SO₄ electrolyte with different concentrations of H₃BO₃ as additive. For the B doped TiO₂ layer fabricated from sulfuric electrolyte having a higher concentration of H₃BO₃ additive, the main XRD peaks of (101) and (200) anatase phase shift gradually toward the lower angle direction, indicating volume expansion of the TiO₂ anatase lattice by incorporation of boron, when compared with TiO₂ layers formed in sulfuric acid with lower concentration of additive. Moreover, XPS results indicate that the center of the binding energy peak of B1s increases from 191.45 eV to 191.98 eV, which suggests that most of boron atoms are doped interstitially in the TiO₂ layer rather than substitutionally. The B doped TiO₂ catalyst fabricated in sulfuric electrolyte with 1.0 M H₃BO₃ exhibits enhanced photocurrent response, and high efficiency and rate constant for dye degradation, which is ascribed to the synergistic effect of the new impurity energy band induced by introducing boron to the interstitial site and the improvement of charge transfer reaction.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.3
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• pp.33-43
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• 2022

South Korea's agricultural nitrogen balance and phosphorus balance rank first and second, respectively, among OECD countries, and proper nutrient management is required to preserve the water quality of rivers and lakes. This study evaluates the effects of furrow mulching on the reduction of non-point source pollution (NPS) load from a sloped upland. The study site was Wanju-gun, Jeollabuk-do, and the survey period was from 2018 to 2019. The slope of the testbed was 13%, and the soil type was sandy loam. The cropping system consisted of maize-autumn Chinese cabbage rotation. The testbed was composed of bare soil (bare), control (Cont.), furrow vegetation mulching (FVM), and furrow nonwoven fabric mulching (FFM) plots. Runoff was collected for each rainfall event with a 1/100 sampler, and the NPS load was calculated by measuring the concentrations of SS, T-N, and T-P. The NPS load was then analyzed for the entire monitoring and crop cultivation periods. During the monitoring period, the effect of reducing the NPS load was 1.5%~44.5% for FVM and 13.1%~55.2% for FFM. During the crop cultivation period, it was 1.2%~80.5% for FVM and 27.0%~65.1% for FFM, indicating that FFM was more effective than FVM. As the NPS load was fairly high during the crop conversion period, an appropriate management method needs to be implemented during this period.

• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.39-49
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• 2022

Bottom ash generated from thermal power plants is mainly disposed in landfills, from which metals may be leached by infiltrating water. To evaluate the effect of metals in leachate on soil and groundwater, we characterized bottom ash generated from burning cokes, bituminous coal, the mixture of bituminous coal and wood pellets, and charcoal powder. The bottom ash of charcoal powder had a relatively large particle size, and its wood texture was well-preserved from SEM observation. The bottom ash of charcoal powder and wood pellets had relatively high K concentration from total element analysis. The eluates of the bottom ash samples had appreciable concentrations of Ca, Al, Fe, SO₄, and NO₃, but they were not a significant throughout the batch test. Therefore, it is considered that there is low possibility of soil and groundwater contamination due to leaching of metal ions and anions from these bottom ash in landfills. To estimate the trend of various trace elements, long-term monitoring and additional analysis need to be performed while considering the site conditions, because they readily adsorb on soil and aquifer substances.

• Korean Journal of Environment and Ecology
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• v.24 no.3
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• pp.279-285
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• 2010

This study was conducted to evaluate the differences between the heavy metal contaminated and non-contaminated Artemisia princeps var. orientalis and Equisetum arvense in litter decomposition processes. The plant samples were collected from abandoned mine tailings and control sites in Cheongyang, South Korea. The abandoned mine tailings have high heavy metal concentration and low soil organic matter contents. The heavy metal contents of mine tailings were about 13 and 28 times higher in As and Cd, compared to those in control soils. Also, the contents of the Cr, Ni and Zn in mine tailings were about 3 to 6 times higher than those in control soil. Samples of two plant species from mine tailings have high heavy metal concentrations compared to those from control sites. The leaf of A. princeps var. orientalis and shoot of E. arvense collected from mine tailings have approximately 23 and 58 times more in As, and 25 and 11 times more in Cd. The mass loss rates of plant litter from mine tailings were slower than those from control sites. During the experimental period, the decomposition of A. princeps var. orientalis leaf from mine tailings and control site showed 50.4% and 65.7% mass loss on the control soil area, respectively. The decomposition of A princeps var. orientalis leaf from mine tailings and control site showed 31.6% and 57.5% mass loss on the mine tailings area, respectively. The decomposition of A. princeps var. orientalis stem from mine tailings and control site showed similar patterns with their leaf decomposition. The decomposition of E. arvense shoot from mine tailings and control site showed 77.8% and 89.3% mass loss on the control soil area, respectively. The decomposition of E. arvense shoot from mine tailings and control site showed 67.6% and 82.1% mass loss on the mine tailings area, respectively. Therefor, the higher contents of heavy metals showed slow decomposition. The results suggested that heavy metal contamination affected the plant litter decomposition processes.

• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.492-500
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• 2008

Since vegetation significantly influences on soil carbon and nutrient storage, vegetation change has been focused on terrestrial carbon and nutrient cycling studies. In this study we investigated soil carbon and major nutrient capitals at the abandoned fields, which had different vegetation composition: a three year abandoned field ($AGR_3$), two ten years abandoned fields ($PD_{10}$ dominant with Pinus densiflora and Fraxinus rhynchophylla and $PM_{10}$ dominant with Populus maximowiczii), and an over sixty years forest ($FOR_{60}$). which were located at Hongcheon-gun, Kangwon-do, South Korea. Both main effects for organic matter (%) were significant: shallow soil > deep soil and $FOR_{60}=PM_{10}$ > $AGR_3=PD_{10}$. Nitrogen concentrations at $PM_{10}$ were the highest, while the lowest at $PD_{10}$. Available phosphorus concentrations were the highest at $PD_{10}$, which were over 10 times of site $FOR_{60}$ and $AGR_3$ at 0-10 cm soil depth. The average organic matter ($173Mg\;ha^{-1}$) and nitrogen contents ($10Mg\;ha^{-1}$) of $PM_{10}$ and $FOR_{60}$ were higher than those of $AGR_3$ and $PD_{10}$ by 57% and 42%, respectively. The available phosphorus contents above 30 cm mineral soil at $PD_{10}$ ($3.8Mg\;ha^{-1}$) and $PM_{10}$ ($1.3Mg\;ha^{-1}$) were over 120 times and 40 times more than at $FOR_{60}$. Calcium ($3.7Mg\;ha^{-1}$) and magnesium contents ($2.8Mg\;ha^{-1}$) at $FOR_{60}$ were twice or three times higher than at other sites. Organic matter amounts in 0-10 cm and 10-30 em soil had significant positive relationships with nitrogen, calcium, and magnesium contents, but not available phosphorus and potassium contents. This study could not identify the effect of chronological factor and vegetation composition on soil carbon and nutrient capital owing to diverse topography as well as limited study sites. However, this study suggests the accuracy of investigation for regional carbon and nutrient sequestration can be achieved by considering the period of abandoned time on the fields and the land use types. These results may suggest the benefits of forest restoration for soil carbon and nutrient accumulation in marginal agricultural lands in South Korea.

• Journal of Environmental Science International
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• v.18 no.6
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• pp.655-665
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• 2009

This study aims to identify the impacts of air quality in the Korean Peninsula according to the China's environmental policies in preparation of the Beijing 2008 Olympic Games. The measurement of emission variations in China, aircraft measurement, and modelling were carried out. The reduction measures in Beijing, China and its emission changes resulted in $30{\sim}65%$ in decrease out of the total emissions within the Beijing region, whereas when it comes to the whole nation of China, the reduction rate was about $4{\sim}9%$. Comparing the concentration of the air pollutants in Seoul and Ganghwa in August 2008 during around the period of Beijing Olympic Games with one in $2004{\sim}2007$ showed that the $SO_2$ concentrations in the past was above 5ppb, while the concentration in the 2008 olympic period was 4ppb and below. The NOx at the Seokmori site in Ganghwa tended to be lower in concentration in 2008 than in between $2004{\sim}2007$. As for $O_3$ and $PM_{2.5}$, the concentration tended to be rather low since August 11. The air current track that showed during the period of aircraft measurement presented to be flowed into Korea through the Northeast part of China and the coast of Bohai Bay, while the concentrations of $SO_2$. NOx, and $O_3$ over the west sea on August 20 and 24 were 0.54 (0.28ppb), 0.86 (1.84ppb), and 54.0 (41.5ppb) respectively, similar or lower than the ones measured in the past in the similar current patterns. The modelling result showed similar patterns to the data of aircraft measurement, in particular in $SO_2$. Overall, the reduction measures in Beijing, China affected directly and indirectly the air quality in the Korean peninsular, but the impact was not significant as it was momentary and limited to the intended area.

• Journal of Environmental Science International
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• v.32 no.12
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• pp.899-914
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• 2023

Various seeding materials for cloud seeding are being used, and sodium chloride powder is one of them, which is commonly used. This study analyzed the experimental results of multi-aircraft cloud seeding in connection with Republic of Korea Air Force (CN235) and KMA/NIMS(Korea Meteorological Administration/National Institute of Meteorological Sciences) Atmospheric Research Aircraft. Powdered sodium chloride was used in CN235 for the first time in South Korea. The analysis of the cloud particle size distributions and radar reflectivity before and after cloud seeding showed that the growth efficiency of powdery seeding material in the cloud is slightly higher than that of hygroscopic flare composition in the distribution of number concentrations by cloud aerosol particle diameter (10 ~ 1000 ㎛). Considering the radar reflectivity, precipitation, and numerical model simulation, the enhanced precipitation due to cloud seeding was calculated to be a maximum of 3.7 mm for 6 hours. The simulated seeding effect area was about 3,695 km², which corresponds to 13,634,550 tons of water. In the precipitation component analysis, as a direct verification method, the ion equivalent concentrations (Na⁺, Cl^-, Ca²⁺) of the seeding material at the Bukgangneung site were found to be about 1000 times higher than those of other non-affected areas between about 1 and 2 hours after seeding. This study suggests the possibility of continuous multi-aircraft cloud seeding experiments to accumulate and increase the amount of precipitation enhancement.

• Journal of Korean Society of Forest Science
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• v.81 no.2
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• pp.117-123
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• 1992

In this study, the water soluble sulfur, lead and cadmium contents of Prunus yedoerais leaves were analysed. The water soluble sulfur content considered as a main pollution indicator was extracted by the conventional barium sulfate method and the concentrations were calculated. The results obtained are as follows ; 1. The water soluble sulfur contents of the leaves collected from the heavy traffic roadside trees were two time higher than that of control materials on average. It was presumed those trees has been under meaningful pollutants impact. The water soluble sulfur contents of leaves between Cheonju and Iri was higher than that between Iri and Kunsan. 2. The range of Pb contents from roadside trees was 11.9-34.5 ppm for exceeding the control. The trees grown on the right roadside were more heavliy Pb-contaminated. 3. The range of Cd contents from roadside trees grown between Iri and Kunsan, the site-to-site variations of Cd concentration was not significant.