• Membrane Journal
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• v.25 no.5
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• pp.373-384
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• 2015

In the past few decades, polymeric membrane has played an important role in gas separation applications. For the separation of $CO_2$, one of greenhouse gases, high permselectivity, long-term stability and scale-up are needed. However, conventional polymeric membranes have shown a trade-off relation between permeability and selectivity while inorganic materials are highly permeable but expensive. Mixed matrix membranes (MMMs) combining the advantages of both polymeric and inorganic materials have become a possible breakthrough for the next-generation gas separation membranes. The MMMs could be either symmetric or asymmetric but the latter is more preferred to improve the permeance. Important factors influencing the MMM fabrication include homogeneous distribution of inorganic particles and good interfacial contact between inorganic filler and organic matrix. Recently, metal organic frameworks (MOFs) have received much attention as a new class of porous crystalline materials and a potential candidate for $CO_2$ separation. Zeolitic imidazolate frameworks (ZIFs), a sub-branch of MOFs, are the most widely used in MMMs due to small particle size and appropriate pore size for $CO_2$ separation. One of the major issues associated with the incorporation of porous particles in a polymeric membrane is to control the microstructure of the porous particle materials such as particle size, orientation, and boundary conditions etc. In this review, major challenges surrounding MMMs and the strategies to tackle these challenges are given in detail.

• Korean Journal of Microbiology
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• v.40 no.1
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• pp.54-59
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• 2004

$\beta$-Glucan has been efficiently produced with higher yield by the optimization of liquid cultivation conditions. The optimal composition of medium for batch culture was 5% (w/v) of glucose as a carbon source, 0.5% (w/v) of yeast and 0.5% (w/v) of malt extract as a nitrogen source, 0.1% (w/v) of $KH_2PO_4$ and 0.05% (w/v) $MgSO_4{\cdot}7H_2O$, which had been the base medium for determination of other conditions. The set-up conditions are pH 5.0, $28^{\circ}C$, 1 vvm for aeration and 300 rpm for agitation. In order to minimize the inhibition effect of glucose on the initial growth of mycelia and to maximize the production of extracellular $\beta$-glucan, we have reduced the initial glucose feed to 4% and added 2nd feed at the point of 70 hr from the initial feed. The 2nd feed was composed of glucose 3%, yeast extract 0.1 % and malt extract 0.1 %. It improved the $\beta$-glucan yield upto 5.2 g/L in comparison with 2.8 g/L resulted from batch cultivation. Moreover, the serial treatment of a cell wall lytic enzyme and bromelain to the mycelia was effective for extraction of the cell wall bound $\beta$-glucan. The yield of $\beta$-glucan extraction by the enzyme treatment was 3.5 g/L, which was almost 4 times higher than that by hot-water extraction.

• Horticultural Science & Technology
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• v.18 no.1
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• pp.18-21
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• 2000

This study was carried out to investigate the MA response of fresh lemongrass (Cymbopogon citratus) depending upon film sources and storage temperatures. The fresh weight loss was significantly lower at 5 and $0^{\circ}C$ than those of higher temperatures. And ceramic $80{\mu}m$ film (CE 80) was more effective in preventing weight loss than CE40. The contents of $CO_2$ and ethylene were much higher in CE 80 wrapping than those in CE 40 ones. Rapid accumulation of $CO_2$ was observed at high storage temperature. However, the ethylene content during whole storage period was higher at $0^{\circ}C$ than those at $5^{\circ}C$, but the level of ethylene was remained below 1ppm and did not adversely affected to lemongrass quality. The treatment of CE 80 at $5^{\circ}C$ was most effective on keeping visual quality and chlorophyll content. The storage durations were up to 48 days at $5^{\circ}C$ and 35 days at $0^{\circ}C$, respectively. Results indicated that CE 80 at $5^{\circ}C$ is an optimal condition for MA storage of lemongrass.

• Journal of Climate Change Research
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• v.9 no.2
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• pp.181-195
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• 2018

On December 12, 2015, the Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) adopted the Paris Agreement, in which several developed and developing countries all committed to participating in the reduction of greenhouse-gas (GHG) emissions. South Korea has submitted an intended nationally determined contribution (INDC) proposal with a target to cut down 37% greenhouse gas business as usual (BAU) until 2030 in preparation for the 2030 GHG BAU. Under the post-2020 regime, which will be launched from 2021 as the agreement entered into force early, it is expected that efforts to support GHG reduction and adaptation to climate change in developing countries will be accelerated with the utilization of technologies and financial resources of developed countries. South Korea has established the Basic Plan for Climate Change Response and the Basic National Roadmap for Greenhouse Gas Reductions by 2030 to promote the response to climate change at the government level. The Ministry of Science and ICT, as the National Designated Entity designated by the UNFCCC, has come up with middle and long-term strategies for climate technology cooperation. South-Korea has an abundance of energy-consuming industries to support its export-oriented industrial structure; it is thus expected that achieving the GHG reduction target will incur a considerable cost. Moreover, in order to meet the reduction target (11.3%) of the intended nationally determined contribution proposed by South Korea, it is necessary for South Korea to actively promote projects that can achieve GHG reduction achievements, and financial resources are needed as leverage to reduce risks that can occur in the early stages of projects and attract private sector investment. This paper summarizes the theoretical discussions on climate finance and conducted a comparative analysis on the status of the funds related to climate change response in the UK, Germany, Japan and Denmark. Through this, we proposed the legal and policy tasks that should be carried forward to raise public funds that can be used for creation of new industries related to climate change as well as to reduce GHG emissions in South Korea. The Climate Change Countermeasures Act, which has been proposed by the National Assembly of South-Korea, stipulates the establishment of funds but there is no additional funding except for general account. In this regard, it is also possible to take measures such as the introduction of carbon tax or the collection and use of royalties through technology research and development projects for climate change, such as Industrial Technology Innovation Promotion Act. In addition, since funds are used in various fields such as domestic greenhouse gas reduction, technology development, and overseas projects, it is necessary to establish a system in which various ministries cooperate with the operation of the fund.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.12 no.2
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• pp.20-52
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• 1999

In order to investigate the effect of Naetakchungumsankamibang(NTCGS) water extract on the skin tumor induced by 3-MCA and immunological responses in mice, the cytotoxicity against SK-MEL-2 cells and total number of tumors induced by 3-MCA were measured. The numbers of WBC, platelets and RBC, plaque forming cells, hemagglutinin titer, hemolysis titer, carbon clearance, proliferation of splenocyte by thymidine uptake assay, splenic leukocyte by FACS analysis and $TNF-{\alpha}$ were also measured for the evaluation of the immunological responses. The results were obtained as follows: 1. In cytotoxicity against SK-MEL-2 cells, concentration inhibiting cell growth up to below $20\%$ of control was recognized at 1mg/ml of NTCGS. 2. In Inhibitory effect on the skin tumor induced by 3-MCA, the results showed a strong inhibitory effect of NTCGS. 3. In hematological changes in the tumor bearing mice, the numbers of WBC decreased significantly in NTCGS treated group as compared with control. 4. In hematological changes in the tumor bearing mice, the numbers of platelets increased significantly in NTCGS treated group as compared with control. 5. In hematological changes in the tumor bearing mice, the numbers of RBC increased with no significance in NTCGS treated group as compared with control. 6. Effects of the plaque forming cells in the tumor bearing mice, NTCGS treated group exhibited a significant effect compared with control. 7. In terms of the effects on hemagglutinin titer, NTCGS treated group showed higher level than control, without significance. 8. In terms of the effects on hemolysis titer, NTCGS treated group showed higher level than control, without significance. 9. In terms of the effects on phagocytic index K in Balb/C mice, NTCGS treated group showed significant difference from control. 10. In terms of the effects on proliferation of splenocyte by thymidine uptake assay, NTCGS showed significant effect at the concentration of 0.5mg/ml. 11. In terms of the effects on splenic leukocyte of Balb/C mice by FACS analysis, NTCGS treated group showed significantly higher level of helper T cell, B cell and macrophage than in control. 12. In terms of the effects on the secretion of $TNF-{\alpha}$, the treated group showed significant effect at the concentration of 1mg/ml of NTCGS. Based on the results summarized above, NTCGS is considered to have antitumor activity and immunological responses against skin tumor, and to be usable fur the treatment.

• Food Science and Preservation
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• v.6 no.4
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• pp.357-364
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• 1999

Modified atmosphere packaging(MAP) technology was applied to ‘Tsugaru’apple (Malus domestica Borkh) in order to extend the shelf-life of apples during distribution. ‘Tsugaru’apples were packed with the PE film of 40 $\mu\textrm{m}$ thickness(40LD), the PE film modified by the addition of 5% (w/w) zeolite (40CK), and the PE film bags containing the ethylene absorbent (40LP). Quality indices of ‘Tsugaru’apples during storage at 10$^{\circ}C$ were measured in terms of weight loss, soluble solids content, pH, titratable acidity, flesh firmness, peel color and sensory properties. Oxygen, carbon dioxide and ethylene concentration in the film bags changed rapidly at the early stage of storage. Weight loss of the control increased up to 3.0% after 60 days storage while those of the packed apples remained less than 0.6%. No significant differences in soluble solids content and titratable acidity could be found in all the treatments, but significant differences in pH between the control and the packed apples. Higher firmness was kept in 40LD and 40LD than other treatments during storage. Color of the peel changed rapidly in control but slowly in 40LD and 40LP. ‘Tsugaru’apples Packed with Packaging films showed a good visual and sensory quality. Results suggest that packaging treatment with LDPE of 40 $\mu\textrm{m}$ thickness and ethylene absorbent can be used for extending the shelf-life of ‘Tsugaru’apples during distribution.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.417-424
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• 2021

Algal bloom is an ongoing issue in the management of freshwater systems for drinking water supply, and the chlorophyll-a concentration is commonly used to represent the status of algal bloom. Thus, the prediction of chlorophyll-a concentration is essential for the proper management of water quality. However, the chlorophyll-a concentration is affected by various water quality and environmental factors, so the prediction of its concentration is not an easy task. In recent years, many advanced machine learning algorithms have increasingly been used for the development of surrogate models to prediction the chlorophyll-a concentration in freshwater systems such as rivers or reservoirs. This study used a light gradient boosting machine(LightGBM), a gradient boosting decision tree algorithm, to develop an ensemble machine learning model to predict chlorophyll-a concentration. The field water quality data observed at Daecheong Lake, obtained from the real-time water information system in Korea, were used for the development of the model. The data include temperature, pH, electric conductivity, dissolved oxygen, total organic carbon, total nitrogen, total phosphorus, and chlorophyll-a. First, a LightGBM model was developed to predict the chlorophyll-a concentration by using the other seven items as independent input variables. Second, the time-lagged values of all the input variables were added as input variables to understand the effect of time lag of input variables on model performance. The time lag (i) ranges from 1 to 50 days. The model performance was evaluated using three indices, root mean squared error-observation standard deviation ration (RSR), Nash-Sutcliffe coefficient of efficiency (NSE) and mean absolute error (MAE). The model showed the best performance by adding a dataset with a one-day time lag (i=1) where RSR, NSE, and MAE were 0.359, 0.871 and 1.510, respectively. The improvement of model performance was observed when a dataset with a time lag up of about 15 days (i=15) was added.

• Membrane Journal
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• v.29 no.1
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• pp.51-60
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• 2019

In order to improve gas separation properties of polymeric membranes which have been widely applied in the industry field, aluminosilicate hollow nanoparticles named as allophanes were synthesized by sol-gel method and formulated in Poly(dimethylsiloxane) (PDMS) matrix to investigate the gas separation properties of PDMS membrane. Transmission electron microscope (TEM), Energy dispersive X-ray analysis (EDX), X-ray diffractometer (XRD), Surface area and pore size analyzer (BET) and Fourier transform infrared spectrophotometer (FTIR) were carried out to characterize the synthetic allophanes. Then the PDMS mixed matrix membranes were prepared by adding different volume fraction of allophanes. To examine the effect of allophanes addition in PDMS matrix using unmodified allophane and modified ones, the gas permeation experiments were performed using oxygen, nitrogen, methane and carbon dioxide. As the volume fraction of modified allophane increased up to 4.05 Vol% the permeability of four test gases through PDMS mixed matrix membranes increased. Also, the selectivity of $O_2/N_2$ and $CO_2/CH_4$ increased with the contents of the modified allophane. Further improvement of gas separation properties of PDMS mixed matrix membranes containing higher volume percent of allophanes can be expected as long as well dispersion of allophanes in PDMS matrix can be achieved for better PDMS membranes.

• Journal of Korea Water Resources Association
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• v.52 no.9
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• pp.637-645
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• 2019

Among various ecosystem services provided by the basin, this study deals with water yield (WY) estimation in the Bagmati basin of Nepal. Maps of where water used for different facilities like water supply, irrigation, hydropower etc. are generated helps planning and management of facilities. These maps also help to avoid unintended impacts on provision and production of services. Several studies have focused on the provision of ecosystem services (ES) on the basin. Most of the studies have are primarily focused on carbon storage and drinking water supply. Meanwhile, none of the studies has specifically highlighted water yield distribution on sub-basin scale and as per land use types in the Bagmati basin of Nepal. Thus, this study was originated with an aim to compute the total WY of the basin along with computation on a sub-basin scale and to study the WY capacity of different landuse types of the basin. For the study, InVEST water yield model, a popular model for ecosystem service assessment based on Budyko hydrological method is used along with ArcGIS. The result shows water yield per hectare is highest on sub-basin 5 ($15216.32m^3/ha$) and lowest on sub-basin 6 ($10847.15m^3/ha$). Likewise, built-up landuse has highest WY capacity followed by grassland and agricultural area. The sub-basin wise and LULC specific WY estimations are expected to provide scenarios for development of interrelated services on local scales. Also, these estimations are expected to promote sustainable land use policies and interrelated water management services.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.371-378
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• 2019

Graphene nanoplatelet (GnP)/reused phenolic foam (re-PF)/wood composite boards were fabricated with different GnP content as 5, 10 and 20 w/w% to investigate the effect of GnP on thermal- and flame retardant properties of wood-based composite boards. The thermal- and flame retardant properties of fabricated composite boards were investigated by thermogravimetric analysis (TGA) and limiting oxygen index (LOI), respectively. The thermal stability of the composite boards increased proportionally with respect to the amount of GnP, and the char yield of these boards increased up to 22% compared to that of the pure wood board. The LOI values of composite boards were about 4.8~7.8% higher than those of using pure wood boards. It was also confirmed that the flame retardant properties of composite boards were remarkably improved by the addition of re-PF and GnP. These results were because of the fact that the re-PF and GnP with a high thermal stability delayed the initial thermal degradation temperature of composite boards and made their char layers denser and thicker which led the overall combustion delay effect of the composite board. Especially, GnP as a carbon-based material, facilitated the char layer formation and increased remarkedly the char yield, which showed higher effect on flame retardant properties than those of the re-PF.