• 한국표면공학회지
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• 제56권6호
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• pp.386-392
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• 2023

In this work, we describe the reduction kinetics of gold nanoparticles synthesized by plasma discharge in aqueous solutions with varied voltages and precursor (HAuCl₄) concentrations. The reduction rate of [AuCl₄]^- was determined by introducing NaBr to the gold colloidal solution synthesized by plasma discharge, serving as a catalyst in the reduction process. We observed that [AuCl₄]^- was completely reduced when its characteristic absorption peak at 380 nm disappeared, indicating the absence of [AuCl₄]^- for ligand exchange with NaBr. The reduction rate notably increased with the rise in discharge voltage, attributable to the intensified plasma generated by ionization and excitation, which in turn accelerated the reduction kinetics. Regarding precursor concentration, a lower concentration was found to retard the reduction reaction, significantly influencing the reduction kinetics due to the presence of active H⁺ and H radicals. Therefore, the production of strong plasma with high plasma density was observed to enhance the reduction kinetics, as evidenced by optical emission spectroscopy.

• 한국산업융합학회 논문집
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• 제25권4_2호
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• pp.549-563
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• 2022

Continuous global warming is causing ecosystem destruction and direct damage to human life. The main cause of global warming is greenhouse gases, which account for more than 90 % of carbon dioxide. The leaders of each country signed the Paris Agreement at the United Nations Convention on Climate Change (UNFCCC) to reduce greenhouse gas emissions. Currently, the total amount of CO₂ emitted from South Korea is 664.7 million tons as of 2018, ranking eighth in the world. 37 % of South Korea's total CO₂ emissions come from the construction & building field, especially the cement production, which is a construction material. Carbon reduction technologies can be largely divided into four types: carbon reduction (CC), carbon reduction and storage technology (CCS), carbon reduction and utilization technology (CCU), and carbon reduction, storage and utilization technology (CCUS). Overseas, CCUS technology is mainly applied to reduce and store CO₂ emitted from construction and construction field. A technology for permanently storing CO₂ through mineralization by capturing CO₂ and utilizing CO₂ into a cement production process was developed, and this technology is applied to the entire cement industry. However, the development of CCUS technology applicable to the cement industry is still insignificant in South Korea. In this study, carbon dioxide reduction technology and methods for reducing carbon dioxide emitted during the cement manufacturing process, which is the main component of concrete mainly used in civil engineering construction, were investigated. Overseas, it has reached the commercialization stage beyond the demonstration stage as a way to reduce carbon dioxide by vomiting carbonation reactions. Accordingly, if carbon dioxide reduction plan technology generated during cement manufacturing is developed based on domestic technology differentiated from foreign technology, it is expected to contribute one more step to the carbon neutrality policy.

• 디지털융복합연구
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• 제16권10호
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• pp.11-26
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• 2018

국가 온실가스 감축수단의 확보를 위해 전략적으로 감축기술을 선택하는 것은 매우 중요한 문제이다. 특히, 공공의 기술선택은 다양한 요인들을 고려하는 포괄적인 접근의 필요성이 강조된다. 그러나 지금까지의 논의들은 기술적, 경제적 요인에 중심을 두고 기술선택을 다루고 있으며, 일관된 선택 기준이 적용되지 않고 있다. 본 연구는 국가 온실가스 감축기술을 선택하기 위한 지표를 개발하고자 전문가 22인을 대상으로 델파이 기법을 사용하였다. 이를 통해 타당성이 확보된 국가 온실가스 감축기술 선택 지표를 개발하였으며, 기술, 경제, 환경, 정책, 사회의 관점을 종합적으로 반영하는 것에 대한 적절성을 확인하였다. 상용화기술은 5개 항목의 16개 지표, 신기술은 5개 항목의 18개 지표로 구성되었다. 본 연구를 통해 제시된 기술선택 지표는 국가 온실가스 감축기술 선택을 위한 의사결정 도구로 활용될 수 있을 것이며, 국가 온실가스 감축기술의 적용과 확보에 관한 판단기준 연구에 토대를 제공할 것으로 기대한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.241-246
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• 2013

The regulation of the aircraft noise has been more strengthened with expansion of the environmental issue. This trend has encouraged the R&D of the noise reduction technology. In this paper, the international efforts for aircraft noise reduction and the related technology were investigated. The aircraft noise sources were also introduced briefly. Additionally, the noise prediction method was explained at the end of paper.

• 한국농공학회논문집
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• 제64권5호
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• pp.41-51
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• 2022

Carbon neutrality is emerging as a new paradigm for the international society by transiting from climate change to climate risk. This study proposes evaluation methods for the carbon reduction contribution of climate-related national R&D projects in order to introduce a green budget system in the agricultural sector. We considered the domestic and foreign green budget systems and classified national R&D projects into positive, negative, and neutral from the perspective of carbon reduction. The results of this study propose three methods to estimate the monetary costs and carbon benefits by adopting the framework for the economic evaluation of national R&D projects conducted by the Rural Development Administration. These methods support to evaluate the potential contribution to carbon reduction of national R&D projects in the agricultural sector. Finally, the proposed methods were tested and verified for the efficiency and validity of evaluating carbon reduction contribution. These evaluation methods of the carbon reduction contribution can be used as a basic methodology for the pre-budget calculations of national R&D projects and the contribution for the greenhouse gas reduction budget.

• Rapid Communication in Photoscience
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• 제4권3호
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• pp.73-75
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• 2015

Cr(VI) reduction was successfully achieved in the presence of cationic micelles (CMs) under visible light illumination. Micelle formation of cationic surfactants seems to be critical in Cr(VI) reduction. Cr(VI) was reduced very fast above the critical micelle concentration (cmc) of CTAB solutions, but was not reduced at all either below or around the cmc of CTAB. The reduction rate of Cr(VI) was enhanced in the absence of dissolved oxygen, supporting that the removal of Cr(VI) should be achieved via a reductive pathway. When CTAB was substituted by Brij 35 or SDS, the reduction of Cr(VI) was negligible. This indicates that the electrostatic interaction between Cr(VI) and headgroups of surfactants is important in the visible light-induced Cr(VI) reduction in micellar solutions.

• Carbon letters
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• 제1권1호
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• pp.17-21
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• 2000

Catalytic reduction and oxidation of NO over polyacrylonitrile based activated carbon fibers (PAN-ACF) under various conditions were carried out to develop removal process of NO from the flue gas. The effect of temperature, oxygen concentration and the moisture content for the reduction of NO with ammonia as a reducing agent was investigated. The reduction of NO increased with the oxygen concentration, but decreased with the increased temperature. The moisture content in the flue gas affects the reduction of NO as the inhibition of the adsorption of the other components and the reaction on the surface of ACE For the oxidation of NO to $NO_2$ over PAN-ACF without using a reducing gas, it showed the temperature and the oxygen concentration of the flue gas are the important factors for the NO conversion in which the conversion increased with oxygen concentration and decreased with the temperature increase and might be the alternative option for the selective catalytic reduction process.

• 한국유기농업학회지
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• 제23권3호
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• pp.455-467
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• 2015

This study analyzed the regional economic feasibility of greenhouse gases (GHGs) reduction technology in paddy rice. Firstly, the impact of GHGs reduction technology on productivity, emission reduction, and costs is different from region to region. Secondly, the water irrigation system contributes to productivity, GHGs reduction, and water reduction, but the profit of paddy rice will decrease because of increase in fixed costs and variable costs. Thirdly, the economic feasibility shows that water-savings plot has a 1.41 in a benefit-cost ratio.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권1호
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• pp.54-62
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• 2014

To better understand dissimilatory iron and sulfate reduction (DIR and DSR) by subsurface microorganisms, we investigated the effects of sulfate and electron donors on the microbial goethite (${\alpha}$-FeOOH) reduction. Batch systems were created 1) with acetate or glucose (donor), 2) with goethite and sulfate (acceptor), and 3) with aquifer sediment (microbial source). With 0.2 mM sulfate, goethite reduction coupled with acetate oxidation was limited. However, with 10 mM sulfate, 8 mM goethite reduction occurred with complete sulfate reduction and x-ray absorption fine-structure analysis indicated the formation of iron sulfide. This suggests that goethite reduction was due to the sulfide species produced by DSR bacteria rather than direct microbial reaction by DIR bacteria. Both acetate and glucose promoted goethite reduction. The rate of goethite reduction was faster with glucose, while the extent of goethite reduction was higher with acetate. Sulfate reduction (10 mM) occurred only with acetate. The results suggest that glucose-fermenting bacteria rapidly stimulated goethite reduction, but acetate-oxidizing DSR bacteria reduced goethite indirectly by producing sulfides. This study suggests that the availability of specific electron donor and sulfate significantly influence microbial community activities as well as goethite transformation, which should be considered for the bioremediation of contaminated environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권2호
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• pp.522-539
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• 2021

In order to solve the problems of the existing audio fingerprint method when extracting audio fingerprints from long speech segments, such as too large fingerprint dimension, poor robustness, and low retrieval accuracy and efficiency, a robust audio fingerprint retrieval method based on feature dimension reduction and feature combination is proposed. Firstly, the Mel-frequency cepstral coefficient (MFCC) and linear prediction cepstrum coefficient (LPCC) of the original speech are extracted respectively, and the MFCC feature matrix and LPCC feature matrix are combined. Secondly, the feature dimension reduction method based on information entropy is used for column dimension reduction, and the feature matrix after dimension reduction is used for row dimension reduction based on energy feature dimension reduction method. Finally, the audio fingerprint is constructed by using the feature combination matrix after dimension reduction. When speech's user retrieval, the normalized Hamming distance algorithm is used for matching retrieval. Experiment results show that the proposed method has smaller audio fingerprint dimension and better robustness for long speech segments, and has higher retrieval efficiency while maintaining a higher recall rate and precision rate.