• Journal of Industrial Technology
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• v.39 no.1
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• pp.7-14
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• 2019

Carbon nanotubes (CNT) on metal substrates are definitely beneficial because they can maintain robust mechanical stability and high conductivity between CNT and metal interfaces. Here, we report direct growth of CNT on Ni-based superalloy, Inconel 600, using thermal chemical vapor deposition (CVD) with acetylene feedstock in the growth temperature range of $400-725^{\circ}C$. Furthermore, we studied the effect of substrate pretreatment on the growth yield enhancement and growth temperature decrease of CNT on Inconel 600. Activation energy (AE) for CNT growth was estimated from the CNT height change with respect to the growth temperature. The AE values significantly decreased from 205.03 to 24.35 kJ/mol by the pretreatment of thermal oxidation of Inconel substrate at $725^{\circ}C$ under ambient. Higher oxidation temperature tends to have lower activation energy. The results have shown the importance of pretreatment temperature on CNT growth yield and growth temperature decrease.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3711-3716
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• 2021

The addition of ferric ferrocyanide (Prussian blue; PB) to adsorbents could enhance the adsorption performance of ¹³³Cs. Toward this goal, we present a heterogeneously integrated carbonaceous material platform consisting of PB in direct contact with CO₂-activated carbon filters (PB-CACF). The resulted sample retains 24.39% more PB than vice versa probed by the ultraviolet-visible spectrometer. We leverage this effect to capture ¹³³Cs in the aqueous environment via the increase in ionic strength and micropores. We note that the amount of PB was likely to be the key factor for ¹³³Cs adsorption compared with specific surface characteristics. The revealed adsorption capacity of PB-CACF was 21.69% higher than the bare support. The adsorption characteristics were feasible and spontaneous. Positive values of 𝜟H^o and 𝜟S^o show the endothermic nature and increased randomness. Based on the concept of capturing hazardous materials via hazardous materials, our work will be of interest within the relevant academia for collecting radionuclides in a sufficient manner.

• Journal of Microbiology and Biotechnology
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• v.29 no.1
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• pp.91-104
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• 2019

The taxonomic and functional characteristics of bacterial communities in the pre-chlorinated rapid filters and ozonated biological activated carbon (BAC) filters were compared using Illumina MiSeq sequencing of the 16S rRNA gene and community-level physiological profiling (CLPP) based on sole-carbon-source utilization patterns. Both the rapid filters and BAC filters were dominated by Rhizobiales within ${\alpha}-proteobacteria$, but other abundant orders and genera were significantly different in both types of filter. Firmicutes were abundant only in the intermediate chlorinated rapid filter, while Acidobacteria were abundant only in the BAC filters. Bacterial communities in the rapid filter showed high utilization of carbohydrates, while those in the BAC filters showed high utilization of polymers and carboxylic acids. These different characteristics of the bacterial communities could be related to the different substrates in the influents, filling materials, and residual disinfectants. Chlorination and ozonation inactivated the existing bacteria in the influent and formed different bacterial communities, which could be resistant to the oxidants and effectively utilize different substrates produced by the oxidant, including Phreatobacter in the rapid filters and Hyphomicrobium in the BAC filters. Bradyrhizobium and Leptothrix, which could utilize compounds adsorbed on the GAC, were abundant in the BAC filters. Ozonation increased taxonomic diversity but decreased functional diversity of the bacterial communities in the BAC filters. This study provides some new insights into the effects of oxidation processes and filling materials on the bacterial community structure in the biological filters of drinking water treatment plants.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.269-274
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• 2022

We prepared carbon nanotube (CNT) paper by a vacuum filtration method for the use of a chip-typed resistor as a precision passive device with a constant resistance. Hybrid resistor composed of the CNT resistor with a negative temperature coefficient of resistance (T.C.R) and a metal alloy resistor with a positive T.C.R could lead to a constant resistance, because the resistance increase owing to the temperature increase at the metal alloy and decrease at the CNT could counterbalance each other. The constant resistance for the precision passive devices should be maintained even when a heat was generated by a current flow resulting in resistance change. Performance reliabilities of the CNT resistor for the precision passive device applications such as electrical load limit, environmental load limit, and life limit specified in IEC 60115-1 must be ensured. In this study, therefore, the rated power determination and T.C.R tests of the CNT paper were conducted. -900~-700 ppm/℃ of TCR, 0.1~0.2 A of the carrying current capacity, and 0.0625~0.125 W of the rated power limit were obtained from the CNT paper. Consequently, we confirmed that the application of CNT materials for the precision hybrid passive devices with a metal alloy could result in a better performance reliability with a zero tolerance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.164-165
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• 2022

In order to solve problems such as acceleration of resource use and environmental pollution, experiments were conducted with the aim of producing indoor finishing materials that can adsorb fine dust and carbon dioxide using gelite and polymer, which are porous materials. Based on the previous experiment, gelite was substituted at each level in a matrix having a polymer S738P substitution rate of 12.5%, and the results are as follows. As the substitution rate of gelite increased, the amount of fine dust and carbon dioxide adsorption increased, which is believed to be due to physical adsorption due to the high porosity of gelite. However, further experiments are needed as the overall adsorption amount is not high due to the filling inside the matrix due to the polymer.

• Journal of Korea Foresty Energy
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• v.18 no.1
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• pp.37-45
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• 1999

The greenhouse effect becomes the most serious environmental problem due to excessive emission of carbon dioxide. This effect is aggravated with the deforestation, particularly cleaning of tropical forest for agricultural use. As trees sequester carbon dioxide from atmosphere, forest and forest products play an important role in the use and reduction of carbon dioxide. Wood and wood products require far less energy than the alternatives such as steel, aluminium and concrete for production. Considering high probability of increasing costs in the use of fossil fuel, the relatively low energy requirement for wood processing to very important. Also wood and wood products perform as a long-term storage of carbon. Wood is therefore an environmentally desirable resource. Recently, many alternatives have been introduced for industrial use. In selecting resources, many aspects should be taken into consideration. Wood and wood products have less harmful effects on the environment than the alternatives. We should utilize wood and wood products more efficiently, which should be provided based on the sustainable forest management.

• Investigative Magnetic Resonance Imaging
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• v.23 no.3
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• pp.241-250
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• 2019

Purpose: The purpose of this study was to determine the relation between quantitative magnetic resonance imaging biomarkers, and clinical performances in chronic phase of carbon monoxide intoxication. Materials and Methods: Eighteen magnetic resonance scans and cognitive evaluations were performed, on patients with carbon monoxide intoxication in chronic phase. Apparent diffusion coefficient (ADC) ratios of affected versus unaffected centrum semiovale, and corpus callosum were obtained. Signal intensity (SI) ratios between affected centrum semiovale, and normal pons in T2-FLAIR (fluid-attenuated inversion recovery) images were obtained. The Mini-Mental State Exam, and clinical outcome scores were assessed. Correlation coefficients were calculated, between MRI and clinical markers. Patients were further classified into poor-outcome and good-outcome groups based on clinical performance, and imaging parameters were compared. T2-SI ratio of centrum semiovale was compared, with that of 18 sex-matched and age-matched controls. Results: T2-SI ratio of centrum semiovale was significantly higher in the poor-outcome group, than that in the good-outcome group and was strongly inversely correlated, with results from the Mini-Mental State Exam. ADC ratios of centrum semiovale were significantly lower in the poor outcome group than in the good outcome group, and were moderately correlated with the Mini-Mental State Exam score. Conclusion: A higher T2-SI and a lower ratio of ADC values in the centrum semiovale, may indicate presence of more severe white matter injury and clinical impairment. T2-SI ratio and ADC values in the centrum semiovale, are useful quantitative imaging biomarkers for correlation with clinical performance in individuals with carbon monoxide intoxication.

• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.579-590
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• 2018

The lakes' metabolism bears important information for the assessment of the carbon budget due to the accumulation or loss of carbon in the lake as well as the dynamics of the food webs through primary production. A lake-scale metabolism is evaluated by Gross Primary Production (GPP), Ecosystem Respiration (R), and Net Ecosystem Production (NEP), which is the difference between the first two values. Methods for estimating GPP and R are based on the levels carbon and oxygen. Estimation of carbon is expensive because of the use of radioactive materials which requires a high degree of proficiency. The purpose of this study was to estimate Lake Daecheong ecosystem metabolism using high frequency water temperature data and DO measurement sensor, widely utilized in the field of water quality monitoring, and to evaluate the possibility of using the application method. High frequency data was collected at intervals of 10 minutes from September to December 2017 by installing a thermistor chain and a DO sensor in downstream of Daechung Dam. The data was then used to estimate GPP, R and NEP using the R public program LakeMetabolizer, and other metabolism models (mle, ols, kalman, bookkeep). Calculations of gas exchange coefficient methods (cole, crusius, heiskanen, macIntyre, read, soloviev, vachon) were compared. According to the result, Lake Daecheong has some deviation based on the application method, but it was generally estimated that the NEP value is negative and acts as a source of atmospheric carbon in a heterotrophic system. Although the high frequency sensor data used in this study had negative and positive GPP and R values during the physical mixing process, they can be used to monitor real-time metabolic changes in the ecosystem if these problems are solved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.157-164
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• 2021

Recently, a number of studies have been conducted on photocatalysts and adsorbents that can remove harmful substances to improve environmental problems related to fine particles. In this study, a porous foam composites were fabricated using palm-based activated carbon having a large amount of micro-pores and foam concrete with a significantly larger total pore volume compared to general construction materials. To evaluate the adsorption potential of fine particles, the pore structure of the foam composites were analyzed. For the analysis of the pore structure of the foam composite, BET and Harkins-jura theory were applied from the measured nitrogen adsorption isotherm. From the results of the analysis, the specific surface area and micro-pore volume of the foam composite containing activated carbon increased significantly compared to Plain. As thereplacement of activated carbon increased, the specific surface area and micro-pore volume of the foam composite tended to increase. It seems that the foam composite has high adsorption performance for gaseous fine particle precursor such as nitrogen oxides.

• Architectural research
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• v.18 no.4
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• pp.145-149
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• 2016

Recently, a goal was set globally to reduce the Carbon Dioxide ($CO_2$) emission at national levels by 30 % in comparison to the Business As Usual (BAU) pursuant to the United Nations Framework Convention on Climate Change. As construction industry accounts for as high as 40 % of the $CO_2$ emission by the entire industrial sector in Korea, efforts toward reducing emissions from the construction industry are essential. Buildings are mainly responsible for $CO_2$ emissions, and, to reduce the $CO_2$ emitted from the buildings, a fast and accurate calculation method is required to be introduced in the architectural design phase. If the standardized data based on Building Information Modelling (BIM) is utilized, $CO_2$ emissions can be calculated quickly and accurately during the design phase. However, it is difficult for the designers who lack the knowledge regarding $CO_2$ emissions to reduce and manage such emission during the planning and design phases of buildings by estimating the quantities of various materials and the corresponding $CO_2$ emissions. Accordingly, the objective of this study is to develop a BIM-based $CO_2$ emission estimation system for a rapid and objective analysis and verification of $CO_2$ emissions.