• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.5
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• pp.15-27
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• 2022

Climate change is considered a severe global problem closely related to carbon storage. However, recent urbanization and land-use changes reduce carbon stocks in terrestrial ecosystems. Recently, the role of protected areas has been emphasized as a countermeasure to the climate change, and protected areas allow the area to continue to serve as a carbon sink due to legal restrictions. This study attempted to expand the scope of these protected areas to an evaluation-based environmental spatial information theme map. In this study, the area of each grade was compared, and the distribution of land cover for each grade was analyzed using the Ecological and Nature Map, Environmental Conservation Value Assessment Map and Urban Ecological Map of Sejong Special Self-Governing City. Based on this, the average carbon storage for each grade was derived using the InVEST Carbon model. As a result of the analysis, the high-grade area of the environmental spatial information generally showed a wide area of the natural area represented by the forest area, and accordingly, the carbon storage amount was evaluated to be high. However, there are differences in the purpose of production, evaluation items, and evaluation methods between each environmental spatial information, there are differences in area, land cover, and carbon storage. Through this study, environmental spatial information based on the evaluation map can be used for land use management in the carbon aspect, and it is expected that a management plan for each grade suitable for the characteristics of each environmental spatial information is required.

• Journal of Environmental Science International
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• v.25 no.4
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• pp.505-516
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• 2016

With the development of nanotechnology, nanomaterials are used in various fields. Therefore, the interest regarding the safety of nanomaterial use is increasing and much effort is diverted toward establishment of exposure assessment and management methods. Occupational exposure limits (OELs) are effectively used to protect the health of workers in various industrial workplaces. This study aimed to propose an OEL for domestic multi-walled carbon nanotubes (MWCNTs) based on animal inhalation toxicity test. Basic procedure for development of OELs was examined. For OEL estimation, epidemiological study and quantitative risk assessment are generally performed based on toxicity data. In addition, inhalation toxicity data-based no observed adverse effect level (NOAEL) and benchmark dose (BMD) are estimated to obtain the OEL. Three different estimation processes (NEDO in Japan, NIOSH in USA, and Baytubes in Germany) of OELs for carbon nanotubes (CNTs) were intensively reviewed. From the rat inhalation toxicity test for MWCNTs manufactured in Korea, a NOAEL of $0.98mg/m^3$ was derived. Using the simple equation for estimation of OEL suggested by NEDO, the OEL of $142{\mu}g/m^3$ was estimated for the MWCNT manufacturing workplace. Here, we used test rat and Korean human data and adopted 36 as an uncertainty factor. The OEL for MWCNT estimated in this work is higher than those ($2-80{\mu}g/m^3$) suggested by previous investigators. It may be greatly caused by different physicochemical properties of MWCNT and their dispersion method and test rat data. For setting of regulatory OELs in CNT workplaces, further epidemiological studies in addition to animal studies are needed. More advanced technical methods such as CNT dispersion in air and liquid should be also developed.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.554-561
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• 1999

A novel estimation method was investigated for determining the concentrations of residual biomass, poly-3-hydroxybutyrate (PHB), and main nutrients including carbon and nitrogen sources, phosphate, and mineral ions from the supplied amount of ammonia solution used for a pH-control solution and nitrogen source in a PHB fermentation. The estimation equations for a batch culture and a fed-batch culture were derived from the relationship between the growth rate of residual biomass and the feed rate of the pH-control solution, and then were applied to the batch culture and the fed-batch cultures of Alcaligenes latus. This method was successfully applied to estimate the concentrations of residual biomass, PHB, and nutrients.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.4
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• pp.411-422
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• 2012

Ground-based in-situ measurements of aerosol optical properties at Gosan climate observatory have been analyzed to investigate the optical contribution of Asian dust and polluted particles on light absorption in springtime 2011. During the Asian dust episode, the contribution of Asian dust particle to aerosol absorption coefficient estimated about 45% at 370 nm and about 23% at 520 nm. Especially, black carbon in dust plume contributes about 48% to aerosol light absorption at 520 nm since the airmass are transported from the Gobi and inner Mongolia deserts, and this airmass comes across the northeastern coast of China, near the Shandong Peninsula. In pollution case, the contributions of dust particle and black carbon to aerosol absorption coefficient estimated about 41% and 11% at 370 nm, respectively. However, pollution case shows the highest light absorption of 48% for brown carbon at 370 nm, which indicates the significantly high mass concentration of organic carbon ($6.3{\pm}2.2{\mu}g\;m^{-3}$) in pollution plume can contribute to the increase of light absorption at near-UV spectral region.

• Composites Research
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• v.16 no.2
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• pp.48-53
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• 2003

This paper presents a study on the permittivities of the I-glass fabric/epoxy composite laminates containing carbon black dispersions at microwave frequency. Measurements were performed at the frequency band of 5 GHz∼18 GHz. The results showed that the complex permittivities of the composites depend strongly on the natures and concentrations of the carbon black dispersion. A new scheme is proposed to obtain a mixing law for the estimation of the complex permittivities of the composite laminates as a function of concentration of carbon black. Simultaneously, the complex permittivity of carbon black itself was also calculated by the scheme. The experimental values of the complex permittivities of the composites were compared to those calculated.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.515-519
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• 2009

Carbon layers were fabricated on silicon carbide by chlorination reaction at temperatures between $1000^{\circ}C$ and $1500^{\circ}C$ with $Cl_2/H_2$ gas mixtures. The effect of reaction temperature on the micro-structures and tribological behavior of SiC derived carbon layer was investigated. Tribological tests were carried out ball-on-disk type wear tester. Carbon layers were characterized by X-ray diffractometer, Raman spectroscopy and surface profilometer. Both friction coefficients and wear rates were maintained low values at reaction temperature up to $1300^{\circ}C$ but increased suddenly above this temperature. Variation of surface roughness as a function of reaction temperature was dominant factor affecting tribological transition behavior of carbon layer derived from silicon carbide at high temperature.

• Journal of Korean Society of Forest Science
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• v.99 no.5
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• pp.673-681
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• 2010

This study examined the biomass data estimated from different allometric models and calculated the mean aboveground biomass, mean belowground biomass and root/shoot ratio values according to the forest types and age classes. These mean values and the forest inventories in 2009 were used to estimate the aboveground and total biomass carbon storage in different forest types (coniferous, deciduous and mixed forests). The aboveground and total biomass carbon storage for all forest types in Korea were 350.201 Tg C and 436.724 Tg C. Over the past 36 years, plantations by reforestation programs have accounted for more than 70% of the observed carbon storage. The carbon storage in Korean forest biomass was 436.724 Tg C, of which 175.154 Tg C for coniferous forests, 126.772 Tg C for deciduous forests and 134.518 Tg C for mixed forests, comprising approximately 1/20 of the total carbon storage of the East Asian countries. The total carbon storage for the whole forest sector in Korea was 1213.122 Tg C, of which 436.724 Tg C is stored in forest biomass if using the ratio of carbon storage in different pools examined from the United States. Such large carbon storage in Korean forests is due mainly to active plantations growth and management practices.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.39-45
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• 2010

Quantification of carbon absorption and understanding the human induced land use changes (LUC) forms one of the major study with respect to global climatic changes. An attempt study has been made to quantify the carbon absorption by LUC through remote sensing technology. The Landsat imagery four time periods was classified with the hybrid classification method in order to quantify carbon absorption by LUC. Thereafter, for estimating the amount of carbon absorption, the stand biomass of forest was estimated with the total weight, which was the sum of individual tree weight. Individual tree volumes could be estimated with the crown width extracted from digital forest cover type map. In particular, the carbon conversion index and the ratio of the $CO_2$ molecular weight to the C atomic weight, reported in the IPCC guideline, was used to convert the stand biomass into the amount of carbon absorption. Total carbon absorption has been modeled by taking areal estimates of LUC of four time periods and carbon factors for land use type and standing biomass. Results of this study, through LUC suggests that over a period of construction, 7.10 % of forest and 9.43 % of barren were converted into urban. In the conversion process, there has been a loss of 6.66 t/ha/y (7.94 %) of carbon absorption from the study area.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.3
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• pp.1-16
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• 2022

The purpose of this study is to quantitatively evaluate the amount of carbon storage for trees in forest ecosystem to support the foundation for carbon neutrality implementation in Korea National Park. It targeted 22 national parks designated and managed as national parks in Korea, and conducted research on forest trees in the terrestrial ecosystem among various natural and ecological carbon sink. The survey and analysis method followed the IPCC guidelines and the National Greenhouse Gas Inventory in Korea. The amount of tree carbon storage in the forest ecosystem of Korea National Park was confirmed to be about 218,505 thousand CO₂-ton and the amount of carbon storage per unit area was 570.8 CO₂-ton per hectare. Compared to 299.7 CO₂-ton per hectare, the average carbon storage per unit area of the entire Korean forest, it was found that about twice as much carbon was stored when assuming the same area. In other words, it means that the tree carbon storage function of the national park is about twice as high as that of the average tree carbon storage function of entire Korean forest. It has great implications in Korea National Park not only provides biodiversity promotion and exploration services as a national protected area, but also performs excellent functions as a carbon sink.

• Particle and aerosol research
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• v.9 no.4
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• pp.231-238
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• 2013

Carbon nanotubes (CNTs) are one of the nanomaterials that were discovered by Iijima in 1991 for the first time. CNTs have long cylindrical and axi-symmetric structures. CNTs are made by rolling graphene sheets. Because of their large length-to-diameter ratio, they are called nanotubes. CNTs are categorized as single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs) based on the shell structures. CNTs are broadly used in various fields, such as scanning probe microscopy, ultra fine nano balance and medicine, due to their extraordinary thermal conductivity, electrical and mechanical properties. Because long, straight CNTs have the same shape as asbestos, which cause cancer in cells lining the lung, there have been many studies on the effects of MWCNTs on human health that have been conducted. Stable atomization of CNTs is very important for the estimation of inhalation toxicity. In the present study, electro-static assisted axial atomizer (EAAA), which is the instrument that uses MWCNTs and aerosolizes them by transforming the single fiber shape using ultrasonic dispersion and electric field, was invented. EAAA consists of a ultrasonic bath for dispersion of MWCNTs and a particle generator for atomizing single fibers. The performance evaluation was conducted in order to assess the possibilities of 6-hour straight atomization with stability, which is the suggested exposure time in a day for the estimation of inhalation toxicity.