• 한국표면공학회지
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• 제53권1호
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• pp.22-28
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• 2020

In this study, manganese dioxide (MnO₂) nanoparticles were synthesized from KMnO₄ and MnCl₂·4H₂O without any dispersing agents and oxidant via ultra-high pressure homogenization process. We investigated various physicochemical properties and CO oxidation reactions of the MnO₂ nanoparticles as a function of the number of passes at 1,500 bar in a high pressure homogenizer nozzle. The observed X-ray diffraction patterns and scanning electron microscopy images revealed that the synthesized MnO₂ nanoparticles had a hexagonal structure and a uniform spherical shape. It was found from the Brunauer-Emmett-Teller measurements that the pore size of the MnO₂ nanoparticles ranged from 23.6 to 7.2 nm and their specific surface area ranged from 24 to 208 m²g^-1. In particular, it was confirmed from the measurements of CO conversion into CO₂ that CO oxidation reaction over the MnO₂ nanoparticles exhibited excellent catalytic activity at low temperatures below 100℃.

• 한국포장학회지
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• 제28권3호
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• pp.217-221
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• 2022

저온에서 신선육을 보관 저장하는 용기의 기체조성을 고CO₂/저O₂ 농도로 자동적으로 제어하는 용기 시스템을 제작하고, 0℃에서 21일간 돼지고기 삼겹살을 담아 저장하면서 품질보전의 측면에서 진공 포장과 함기 대조구 조건과 비교하였다. CO₂ 주입 시간 프로그램에 의하여 CO₂ 농도는 47~60%, O₂ 농도는 7~10%로 유지될 수 있었고, 이는 호기적 세균 증식과 pH 증가의 억제의 효과와 함께 관능적 품질유지에 기여하였다. 진공포장은 함기 대조구에 비하여 낮은 미생물 성장과 pH 증가를 보여주었으나 높은 drip 손실의 단점을 보였다. 전체적 품질보존의 측면에서 고안된 고CO₂ 치환 용기는 육류의 품질유지에 효과적이며, 육류의 종류와 특성에 맞게 기체 농도 조건을 변경하여 활용범위를 확장할 수 있을 것이다.

• KSBB Journal
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• 제11권3호
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• pp.295-302
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• 1996

Rubisco의 parameter들을 측정하는 것은 광합성 연구에 대단히 중요한데, 본 연구에서는 방사성통위 원소를 사용하는 방법 이 아닌 photometric assay 방 법을 사용하여 parameter를 측정하였다. Rubisco 의 activation과 carbamylation에 미치는 고 CO2 놓도의 효과를 연구하기 위하여, 정상 $CO_2$ 농도 (350 ppm)와 고 $CO_2$ 농도(650 ppm)에서 기른 kidney bean (Phaseolus vulgaris L.) 잎을 각각 재료로 하여, dual beam(334 nm9-} 405 nm) spectro­p photometer를 사용하여 rubisco의 initial activity 와 total activity, carbamylation rate 및 量을 측정 비교하였으며, SDS-PAGE에 의해 rubisco의 전기 영통 profile을 분석하였다. 정상 $CO_2$ 농도에서의 initial activity와 total activity는 $41.2{\mu}M/m^2/s 와 52.2{\mu}M/m^2/s$이며, 고 $CO_2$ 농도에서는 $27.4{\mu}M/m^2/s 와 46.1{\mu}M/m^2/s$로서, 350 ppm에서 650 ppm으로 $CO_2$ 농도를 증가시키면 rubisco의 initial activity와 total activity가 갑소되었다. 또한 carbamylation율도 정상 $CO_2$ 농도에서는 79%이며, 고 $CO_2$ 농도에서는 58.9%로서, $CO_2$ 농도의 증가에 따라 감소되 었다. Rubisco 의 量은 정상 $CO_2$농도에서는 $1.94 {\mu}M/m^2$$ 임에 반해 고 $CO_2$ 농도에서는 $1.58{\mu}M/m^2$ 로서, $CO_2$2 농도는 증가되었는데 그 量은 감소되었다. 이와 같이 고 $CO_2$농도에셔 rubisco의 activity가 감소되는 것은 rubisco의 carbamylation에 기인되는 것으로 생각된다. SOS-PAGE 분석에서 50kO 분자량의 large s subunit와 14.5 kO의 분자량을 가지는 small subu n mt를 동정하였는데, 고 $CO_2$ 농도와 정상 $CO_2$ 농도 의 50kD와 14.5 kO band의 intensity를 비교하면 두 구 사이에 큰 차이가 발견되지 않았다. 고 CO2 농도에서 정상 $CO_2$ 농도로 switch한 rubisco의 parameter는 정상 $CO_2$ 농도에서의 pa­r rameter와 거의 비슷한 값을 나타내였는데, 이는 350 ppm의 정상 $CO_2$ 농도에 의해 rubisco의 acti­v vity가 회복되었음을 의미한다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제29권1호
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• pp.1-9
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• 2024

As part of monitoring technology aimed at verifying the stability of CO₂ geologic storage and mitigating concerns about leakage, a method for measuring the pH and alkalinity of high-pressure fluid samples was established to obtain practical technology. pH measurement for high-pressure samples utilized a high-pressure pH electrode, and alkalinity was measured using the Gran titration method for samples collected with a piston cylinder sampler (PCS). Experimental samples, referencing CO₂-rich water and CO₂ geologic storage studies, were prepared in the laboratory. The PCS controls the piston, preventing CO₂ degassing and maintaining fluid pressure, allowing mixing with KOH to fix dissolved CO₂. Results showed a 6.1% average error in high-pressure pH measurement. PCS use for sample collection maintained pressure, preventing CO₂ degassing. However, PCS-collected sample alkalinity measurements had larger errors than non-PCS measurements, limiting PCS practicality in monitoring field settings. Nevertheless, PCS could find utility in preprocessing for carbon isotope analysis and other applications. This research not only contributes to the field of CCS monitoring but also suggests potential applications in studies related to natural analogs of CCS, CO₂-rock interaction experiments, core flooding experiments, and beyond.

• 한국가스학회지
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• 제24권6호
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• pp.77-82
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• 2020

본 논문에서는 자연냉매로 주목받고 있는 이산화탄소(CO2) 를 이용하여 냉동탑차용 고효율 냉동시스템을 개발하였다. 기존의 디젤 차량을 LNG 차량으로 개조하여, 화물차의 배출가스를 개선하고, LNG 연료의 기화 잠열을 활용하여 CO2 냉동시스템의 효율을 높인 친환경적인 냉동탑차를 개발하였다. 그 결과 가스 쿨러에 LNG연료의 기화 잠열을 활용하여 냉동탑차의 COP를 144%로 향상 시켰다.

• 한국도로학회논문집
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• 제18권5호
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• pp.83-93
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• 2016

PURPOSES : The aim of this article is to compare and identify eco-friendly competitiveness between (regional) motorway and high-speed rail(HSR) from the perspective of $CO_2$ emission in the Republic of Korea. METHODS : In order for an analysis of low-carbon competitiveness between the two modes, $CO_2e$ emission, $CO_2eppk$ (equivalent $CO_2$ gram per passenger kilometer), is employed as a comparison index. As for HSR, the index is calculated based on the passenger transport data and the gross of $CO_2e$ produced by Kyungbu high-speed line in 2013. Additionally, the gross of $CO_2e$ is computed by the greenhouse gas emission factors of domestic electricity generation mix. Regarding the index of motorway, it is directly calculated using both the official $CO_2e$ emission factor and the passenger-car occupancy of motorway. RESULTS : The results revealed, in the case of inter-regional transport, that the $CO_2e$ emission of displacement-based cars is 54.9% less than that of HSR, as the domestic electric power systems heavily relies on the thermal power plants over 66%. Note that internal combustion engines commonly used for vehicles are more energy-efficient than steam-driven turbines usually utilized for thermal power generation. CONCLUSIONS : It can be seen, at the very least in our study, that HSR has no superiority over motorway in the case of $CO_2e$ emission under the situations of domestic electricity generation mix. In addition, advanced eco-friendly vehicles have strong advantages over HSR. Therefore, all-out efforts should be made to develop and harvest renewable energy sources in order to achieve low-carbon HSR, sparing fossil fuels.

• 한국표면공학회지
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• 제39권3호
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• pp.129-136
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• 2006

The high velocity oxy-fuel sprayed coatings of 38Ni-23Co-20Cr-11Al-3Y-5Ta, 25Ni-34Co-20Cr-11Al-3Y-2Re and 32Ni-34.5Co-22Cr-11Al-0.5Ir (in wt%) were oxidized at 1000 and $1100^{\circ}C$ in air in order to find the alloying effect of Ta, Re and Ir on the oxidation properties of the NiCoCrAlY-base coatings. The primary phase of the coatings was $Ni_3Al$. The oxides formed on the coatings consisted primarily of ${\alpha}-Al_2O_3$, together with some $CoCr_2O_4,\;CoAl_2O_4$, and $Al_5Y_3O_{12}$. Tantalum oxidized to $Ta_2O_5$ and $Ta_2O_{22}$. However, no oxides of Re and Ir were detected by XRD owing to their thermodynamic inertness and/or their small amount.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.683-689
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• 2014

Since $CO_2$ concentrations in industrial flue gases are usually 10%-20%, one of the prerequisites for efficient $CO_2$ removal by algae is the level of tolerance of microalgal species to exposure to high concentrations of $CO_2$. A newly isolated microalgal strain, Chlorella sp. MRA-1, could retain growth with high concentrations of $CO_2$ up to 15%. The highest lipid productivity for Chlorella sp. MRA-1 was 0.118 g/l/day with a 5% $CO_2$ concentration. Octadecenoic acid and hexadecanoic acid, the main components of biodiesel, accounted for 70% of the total fatty acids. A lipid content of 52% of dry cell weight was achieved with limited amounts of nitrogen. Chlorella sp. MRA-1 seems to be an ideal candidate for biodiesel production when cultured with high concentrations of $CO_2$.

• Bulletin of the Korean Chemical Society
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• 제9권6호
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• pp.333-337
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• 1988

Spinel $CoFe_2O_4$ solid solutions containing up to 50 mol% CoO were synthesized with spectroscopically pure CoO and ${\alpha}-Fe_2O_3$ polycrystalline powders. The spinel structures of the $CoFe_2O_4$ solid solutions were analyzed from XRD patterns and the Mossbauer spectra showed that the quenched $CoFe_2O_4$ had a partially inversed spinel structure ($Co_{0.23}Fe_{0.77}$) < $Co_{0.77}Fe_{1.23}$ > $O_4$, while the slowly cooled $CoFe_2O_4$ was completely inversed spinel ($Co_{0.04}Fe_{0.96}$) <$Co_{0.96}Fe_{1.04}$ > $O_4$. The $CoFe_2O_4$ specimens containing 10, 20, 30 and 40 mol% CoO turned to be a mixture of corundum and spinel structures. Electrical conductivities were measured as a function of temperature from 300 to $900^{\circ}C$ under oxygen partial pressures from $10^{-3}$ to 1 atm. The temperature dependencies of the electrical conductivity show different behaviors in the low- and high-temperature regions. The average activation energies are 0.23 eV and 0.80 eV in the low- and high-temperature regions, respectively. It is suggested that $Co^{2+} {\to} CO^{3+} + e^-$ and $Fe^{2+} {\rightleftharpoons} Fe^{3+} + e^-$ are the main conduction mechanisms responsible for the electronic conduction in the low- and high-temperature regions, respectively.

• 한국세라믹학회지
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• 제49권3호
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• pp.205-215
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• 2012

It has been studied the crystal and block structures of the hexagonal ferrites with M, W, Y and Z types prepared by various coprecipitation-oxidation method. The structures have been refined with a Rietveld analysis of the powder X-ray diffraction pattern with high precision ($R_{WP}$ <0.09, $R_I$ <0.03). The density difference between the S-blocks was proportioned to the cobalt contents in hexagonal ferrites, but that between the R or T-blocks was relatively small. Compared with the blocks and cation-oxygen polyhedra in BaM ($BaFe_{12}O_{19}$), those were bulky to the normal direction for the c-axis in $Co_2W$ ($BaCo_2Fe_{16}O_{27}$) and to the parallel direction for the c-axis in $Co_2Y$ ($Ba_2Co_2Fe_{12}O_{22}$) and $Co_2Z$ ($Ba_3Co_2Fe_{24}O_{41}$). The S-blocks of $Co_2W$, $Co_2Y$, and $Co_2Z$ were unstable and distorted. Because the T-block of $Co_2Z$ was unstable, the T-block was decomposed into the Ba-rich phase and $Co_2W$ at high temperatures above $1200^{\circ}C$. A standard powder X-ray diffraction pattern for $Co_2Z$ was proposed as well.