• Journal of Wetlands Research
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• v.20 no.4
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• pp.363-369
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• 2018

One of the recent environmental problems is climate change due to the increase of atmospheric $CO_2$, which causes ecological changes and various environmental problems. Therefore, various studies are being carried out to reduce $CO_2$ in the world in order to solve various environmental problems caused by increase of $CO_2$. The $CO_2$ reduction using microalgae is an environmentally friendly method by using photosynthesis reaction of microalgae. However, most studies using single species. There is no study on the $CO_2$ fixing efficiency of microalgae in natural rivers. Therefore, this study was to identify the microalgae in the Sum river and to analyze the growth characteristics of microalgae in the river to obtain optimal culture conditions. And the changes of biomass and chlorophyll-a of microalgae were analyzed according to $CO_2$ concentration and injection rate. The purpose of this study was to investigate the fixing efficiency of carbon dioxide in microalgae in natural rivers. Six kinds of dominant species were observed as a result of the identification of microalgae in Sum river(Ankistrodesmus falcatus, Scenedesmus intermedius, Selenodictyum sp., Xanthidium apiculatum var. laeve, Cosmarium pseudoquinarium, Dictyosphaerium pulchellum). All of these species were green algae. Biomass and chlorophyll-a increased with the increase of $CO_2$ concentration and biomass and chlorophyll-a increased faster flow rate at the same $CO_2$ concentration. Also, the quantity of $CO_2$ fixation on the microalgae tended to be higher when the flow rate of injected gas was faster. This study can be referred as being significant in the micro-algae in river. In addition, the optimal conditions for $CO_2$ fixation of microalgae in rivers and the quantification of the quantity of $CO_2$ fixation from microalgae in rivers can be used as basic data for future policy of $CO_2$ reduction.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.375-388
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• 2019

Accurate evaluation of sea-to-air $CO_2$ flux and its variability is crucial information to the understanding of global carbon cycle and the prediction of atmospheric $CO_2$ concentration. $fCO_2$ observations are sparse in space and time in the East Sea. In this study, we derived high resolution time series of surface $fCO_2$ values in the southwest East Sea, by feeding sea surface temperature (SST), salinity (SSS), chlorophyll-a (CHL), and mixed layer depth (MLD) values, from either satellite-observations or numerical model outputs, to three machine learning models. The root mean square error of the best performing model, a Random Forest (RF) model, was $7.1{\mu}atm$. Important parameters in predicting $fCO_2$ in the RF model were SST and SSS along with time information; CHL and MLD were much less important than the other parameters. The net $CO_2$ flux in the southwest East Sea, calculated from the $fCO_2$ predicted by the RF model, was $-0.76{\pm}1.15mol\;m^{-2}yr^{-1}$, close to the lower bound of the previous estimates in the range of $-0.66{\sim}-2.47mol\;m^{-2}yr^{-1}$. The time series of $fCO_2$ predicted by the RF model showed a significant variation even in a short time interval of a week. For accurate evaluation of the $CO_2$ flux in the Ulleung Basin, it is necessary to conduct high resolution in situ observations in spring when $fCO_2$ changes rapidly.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.183-200
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• 2019

In this study, the characteristics of seasonal $PM_{2.5}$ behavior in South Korea and other Northeast Asian regions were analyzed by using the $PM_{2.5}$ ground measurement data, weather data, WRF and CMAQ models. Analysis of seasonal $PM_{2.5}$ behavior in Northeast Asia showed that $PM_{2.5}$ concentration at 6 IMS sites in South Korea was increased by long-distance transport and atmospheric congestion, or decreased by clean air inflow due to seasonal weather characteristics. As a result of analysis by applying BFM to air quality model, the contribution from foreign countries dominantly influenced the $PM_{2.5}$ concentrations of Baengnyeongdo due to the low self-emission and geographical location. In the case of urban areas with high self-emissions such as Seoul and Ulsan, the $PM_{2.5}$ contribution from overseas was relatively low compared to other regions, but the standard deviation of the season was relatively high. This study is expected to improve the understanding of the air pollutant phenomenon by analyzing the characteristics of $PM_{2.5}$ behavior in Northeast Asia according to the seasonal weather condition change. At the same time, this study can be used to establish the air quality policy in the future, knowing that the contribution of $PM_{2.5}$ concentration to the domestic and overseas can be different depending on the regional emission characteristics.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.90-104
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• 2019

In this study, CALPUFF modeling was performed, using a real surface and upper air meterological data to predict trustworthy modeling-results. Pollutant-releases from windscreen chambers of enclosed poultry farms, P1 and P2, and from a open poultry farm, P3, and their diffusing behavior were modeled by CALPUFF modeling with volume sources as well as by finally-adjusted CALPUFF modeling where a linear velocity of upward-exit gas averaged with the weight of each directional-emitting area was applied as a model-linear velocity ($u^M_y$) at a stack, with point sources. In addition, based upon the scenario of poultry farm-releasing odor and particulate matter (PM) removal efficiencies of 0, 20, 50 and 80% or their corresponding emission rates of 100, 80, 50 and 20%, respectively, CALPUFF modeling was performed and concentrations of odor and PM were predicted at the region as a discrete receptor where civil complaints had been frequently filed. The predicted concentrations of ammonia, hydrogen sulfide, $PM_{2.5}$ and $PM_{10}$ were compared with those required to meet according to the offensive odor control law or the atmospheric environmental law. Subsequently their required removal efficiencies at poultry farms of P1, P2 and P3 were estimated. As a result, a priori assumption that pollutant concentrations at their discrete receptors are reduced by the same fraction as pollutant concentrations at P1, P2 and P3 as volume source or point source, were controlled and reduced, was proven applicable in this study. In case of volume source-adopted CALPUFF modeling, its required removal efficiencies of P1 compared with those of point source-adopted CALPUFF modeling, were predicted similar each other. However, In case of volume source-adopted CALPUFF modeling, its required removal efficiencies of both ammonia and $PM_{10}$ at not only P2 but also P3 were predicted higher than those of point source-adopted CALPUFF modeling. Nonetheless, the volume source-adopted CALPUFF modeling was preferred as a safe approach to resolve civil complaints. Accordingly, the required degrees of pollution prevention against ammonia, hydrogen sulfide, $PM_{2.5}$ and $PM_{10}$ at P1 and P2, were estimated in a proper manner.

• Journal of Climate Change Research
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• v.2 no.4
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• pp.283-295
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• 2011

Many actions against climate change have been taken to reduce greenhouse gases (GHGs) emissions at home and abroad. As of 2007, the GHGs emitted from buildings accounted for about 23 % of Korea's total GHGs emission, which is the second largest GHG reduction potential following industry. In this study, we introduced Carbon Zero Building (CZB), which was constructed by the National Institute of Environmental Research to cut down GHGs from buildings in Korea, and evaluated the main applied technologies, the amount of energy load and reduced energy, and economic values for CZB to provide data that could be a basis in the future construction of this kind of carbon-neutral buildings. A total of 66 technologies were applied for this building in order to achieve carbon zero emissions. Applied technologies include 30 energy consumption reduction technologies, 18 energy efficiency technologies, and 5 eco-friendly technologies. Out of total annual energy load ($123.8kWh/m^2$), about 40% of energy load ($49kWh/m^2$) was reduced by using passive technologies such as super insulation and use of high efficiency equipments and the other 60% ($74.8kWh/m^2$) was reduced by using active technologies such as solar voltaic, solar thermal, and geothermal energy. The construction cost of CZB was 1.4 times higher than ordinary buildings. However, if active technologies are excluded, the construction cost is similar to that of ordinary buildings. It was estimated that we could save annually about 102 million won directly from energy saving and about 2.2 million won indirectly from additional saving by the reduction in GHGs and atmospheric pollutants. In terms of carbon, we could reduce 100 ton of $CO_2$ emissions per year. In our Life Cycle Cost (LCC) analysis, the Break Even Point (BEP) for the additional construction cost was estimated to be around 20.6 years.

• Journal of Climate Change Research
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• v.4 no.2
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• pp.115-126
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• 2013

Recently Korea considers the source of biomass burning emissions reflecting national characteristic, so that includes the inventory of emission source but preceding research is rarely implemented in Korea. Therefore, a study on characteristics of greenhouse gas emissions from biomass burning is necessary and it also makes the source management effectively when the climate-atmospheric management system takes effect. In this study, using the manufactured charcoal kiln and the number of experiment was three times to get a reliable experiment result. The sampling time was decided by changing degree in charcoal kiln and charcoal manufacturing process. The results of calculation greenhouse gas emission factor from charcoal kiln were $668g\;CO_2/kg$, $20g\;CH_4/kg$, $0.01g\;N_2O/kg$. Using the emission factor developed in this study, estimate the emissions from charcoal kiln in Korea. The results of calculation were $46,040ton\;CO_2/yr$, $1,378ton\;CH_4/yr$, $0.69ton\;N_2O/yr$ and greenhouse gas emissions applying GWP are as follows. $CH_4$ emissions was $28,947ton\;CO_2eq./yr$, $N_2O$ emissions was $214ton\;CO_2eq./yr$. As a results, Gross emissions of charcoal kiln in Korea was $75,201ton\;CO_2eq./yr$, but the oak used in this study is included to the biomass so emissions of $CO_2$ are excluded. Therefore the net emissions of charcoal kiln in Korea was $29,161ton\;CO_2eq./yr$.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1038-1047
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• 2018

This study confirmed possibility of cosmetic material for Espresso coffee grounds extracted at high temperature, high pressure, short time and Dutch coffee grounds extracted at low temperature, atmospheric pressure, long time. For this purpose, we evaluated the biological activities of antioxidant, anti-wrinkles and antimicrobial effects using ethanol extracts of Esproso and Dutch coffee grounds. The results of total polyphenolic compound contents was $90.39{\pm}0.04mg/g$ for Dutch coffee grounds extract, which was higher than $64.96{\pm}0.38mg/g$ for Espresso coffee grounds extract, based on $113.63{\pm}0.22mg/g$ for coffee beans extract as the reference one. DPPH radical scavenging activity and SOD-like activity of Dutch coffee grounds extract were found to be better than those of Espresso coffee grounds extracts, referenced on coffee bean extract. As a result of inhibition effect of Elastase activity, Dutch coffee grounds extract showed higher inhibition effect than Espresso coffee grounds extract, based on coffee bean extract. In addition, Dutch coffee grounds extract showed good anti-microbial effects at Escherichia coli, Bacillus, Propionibacterium acnes and there was little difference in the clear zone size between Dutch coffee grounds extract and coffee bean extract as a reference one. From the results of the experiments, it was confirmed that Dutch coffee grounds extract had excellent antioxidant, anti-wrinkle and antimicrobial effects and could be used as safe natural cosmetic material in the future.

• Clean Technology
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• v.25 no.3
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• pp.245-255
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• 2019

Pressurized oxy-fuel combustion is a promising technology for $CO_2$ capture with a benefit of improving power plant efficiency compared with atmospheric oxy-fuel combustion. Prior to $CO_2$ compression in this process, a flue gas condenser (FGC) is used to remove $H_2O$ while recovering the latent heat. At the same time, the FGC has a potential for high-efficiency removal of $SO_x$ and $NO_x$ by exploiting their good solubility in water. In this study, experiments were carried out in a lab-scale, direct contact FGC under different pressures varying between 1 and 20 bar to evaluate the removal efficiency of $SO_2$ and $NO_x$ for individual gases and their mixture. In the tests for individual gases, 20% and 76% of $NO_x$ was removed at 1 bar and 10 bar, respectively. Even higher removal efficiencies were achieved for $SO_2$, and also these were maintained for longer as the pressure increased. In the tests for $SO_2$ and $NO_x$ mixture, the removal efficiency of $NO_x$ increased from 13% at 1 bar to 56% at 20 bar because of higher solubility at elevated pressures. $SO_2$ in the mixture was initially dissolved almost completely and then increased by 1,219 ppm at 1 bar and by 165 ppm at 20 bar. Overall, the removal efficiency of $SO_2$ and $NO_x$ was increased at elevated pressures, but it was lower in the mixture compared with individual gases at identical conditions because of a lower pH and associated chemical reactions in water.

• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.251-263
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• 2019

Sentinel-2 Multi Spectral Instrument(MSI) launched by the European Space Agency (ESA) offered high spatial resolution optical products, enhanced temporal revisit of five days, and 13 spectral bands in the visible, near infrared and shortwave infrared wavelengths similar to Landsat mission. Landsat satellite imagery has been applied to various previous studies, but Sentinel-2 optical satellite imagery has not been widely used. Currently, for global coverage, Sentinel-2 products are systematically processed and distributed to Level-1C (L1C) products which contain the Top-of-Atmosphere (TOA) reflectance. Furthermore, ESA plans a systematic global production of Level-2A(L2A) product including the atmospheric corrected Bottom-of-Atmosphere (BOA) reflectance considered the aerosol optical thickness and the water vapor content. Therefore, the Sentinel-2 L2A products are expected to enhance the reliability of image quality for overall coverage in the Sentinel-2 mission with enhanced spatial,spectral, and temporal resolution. The purpose of this work is a quantitative comparison Sentinel-2 L2A products and fully simulated image to evaluate the applicability of the Sentinel-2 dataset in cultivated land growing various kinds of crops in Korea. Reference image of Sentinel-2 L2A data was simulated by airborne hyperspectral data acquired from AISA Fenix sensor. The simulation imagery was compared with the reflectance of L1C TOA and that of L2A BOA data. The result of quantitative comparison shows that, for the atmospherically corrected L2A reflectance, the decrease in RMSE and the increase in correlation coefficient were found at the visible band and vegetation indices to be significant.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2013.11a
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• pp.23-24
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• 2013

Micrometeorological fluxes measured over a tall forest in a complex terrain are difficult to interpret. $CO_2$ storage often makes significant contributions to net ecosystem exchange of $CO_2$ (NEE) in early morning and during nighttime due to calm and stable conditions. We measured the above-canopy $CO_2$ flux along with its concentration profiles at eight levels within and above the canopy to evaluate $CO_2$ storage term. Our question is whether or not the $CO_2$ storage term can be estimated accurately from a single level measurement of $CO_2$ concentration in a complex terrain. Our objectives are (1) to document vertical profiles of $CO_2$ concentration and (2) to compare the diurnal and seasonal variations of $CO_2$ storages estimated from single and multi-level $CO_2$ concentration data. Seasonally averaged Diurnal variations of $CO_2$ concentration ranged from 398 to 455 ppm near the forest floor at 0.1 m whereas they ranged from 364 to 395 ppm at 40 m in the atmosphere. The diurnal variation of vertical profiles of $CO_2$ concentration shows very interesting features with season. At all eight levels, diurnal variation of $CO_2$ concentration showed little change in winter. In spring, the diurnal variations of $CO_2$ concentration at 8 levels showed three distinct groups of layers with height: the first layer: 0.1m (near surface), second layer: 1.0 m and 4.0m (below canopy) and the third layer: 7.4m to 40.7 m (near canopy and above). In summer, these three groups of layers were further separated with larger variations whereas such distinction became smaller in fall. The diurnal variation of $CO_2$ concentration in the first three layers near surface always showed higher concentration with larger variability. Typically, $CO_2$ concentration showed peaks in early morning and in the evening. After the evening peak, $CO_2$ concentration gradually increased except for those near the surface (i.e., 0.1, 1.0 and 4.0 m) where the concentrations actually decreased. We suspect that this could be attributed to the drainage flow of $CO_2$ along the hill slope from the headwater to downstream, which is not taken into account for net ecosystem $CO_2$ exchange. In comparison to the results of other studies, the distinct and different vertical structures of $CO_2$ concentrations observed at our site may be due to complex terrain and weak turbulent mixing under calm conditions at the site. The annual mean of diurnal variation of $CO_2$ storage flux from single level ranged from -0.6 to $0.9{\mu}mol\;m^{-2}s^{-1}$ and from multi-level from -1.2 to $1.0{\mu}\;{\mu}mol\;m^{-2}s^{-1}$. When compared against the results from the multi-level concentrations, the storage flux estimated from a single-level concentration was generally adequate except for specific hours near sunrise and sunset. Further details and their implication will be discussed in the presentation.