• Transactions of the Korean hydrogen and new energy society
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• v.24 no.2
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• pp.128-135
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• 2013

The nuclear fuel cycle plant is composed of various subsystems such as a fuel storage and delivery system (SDS), a tokamak exhaust processing system, a hydrogen isotope separation system, and a tritium plant analytical system. Korea is sharing in the construction of the International Thermonuclear Experimental Reactor (ITER) fuel cycle plant with the EU, Japan, and the US, and is responsible for the development and supply of the SDS. Hydrogen isotopes are the main fuel for nuclear fusion reactors. Metal hydrides offer a safe and convenient method for hydrogen isotope storage. The storage of hydrogen isotopes is carried out by absorption and desorption in a metal hydride bed. These reactions require heat removal and supply respectively. Accordingly, the rapid storage and delivery of hydrogen isotopes are enabled by a rapid cooling and heating of the metal hydride bed. In this study, we designed and manufactured a vertical-type hydrogen isotope storage bed, which is used to enhance the cooling performance. We present the experimental details of the cooling performances of the bed using various cooling parameters. We also present the modeling results to estimate the heat transport phenomena. We compared the cooling performance of the bed by testing different cooling modes, such as an isolation mode, a natural convection mode, and an outer jacket helium circulation mode. We found that helium circulation mode is the most effective which was confirmed in our model calculations. Thus we can expect a more efficient bed design by employing a forced helium circulation method for new beds.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.300-306
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• 2014

In this study, we investigated the noble metal catalysts for HCHO removal at room temperature. These catalysts were characterized by XRD, FT-IR, CO-chemisorption. As a result, Pt and Pd based catalysts prepared by the reduction treatment showed the superior HCHO oxidation ability at room temperature. When the catalysts were prepared using $TiO_2$ support, which is well known as the reducing support, showed the superior activity. Also, the activity decreased by the agglomeration of active metal with increasing the reduction time. In case of reduction catalysts, it has been confirmed that the desorption and adsorption ability properties of HCHO is excellent at room temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.314-320
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• 2021

Controlling ambient humid condition through high performance humidity sensors has become important for various fields, including industrial process, food storage, and the preservation of historic remains. Although aerosol deposited humidity sensors using ceramic BaTiO₃ (BT) material have been widely studied because of their longtime stability, there remain critical disadvantages, such as low sensitivity, low linearity, and slow response/recovery time in case of the sensors fabricated at room temperature. To achieve superior humidity sensing properties even at room temperature condition, BT-Cu composite films utilizing aerosol deposition (AD) process have been proposed based on the percolation theory. The BT-Cu composite films showed gradually improved sensing properties until the Cu concentration reached 15 wt% in the composite film. However, the excessive Cu (above 30 wt%) containing BT-Cu composite films showed a rapid decrease of the sensing properties. The results of observed surface morphology of the AD fabricated composite films, to figure out the metal filler effect, showed correlation between surface topography as well as size and the amount of open pores according to the metal filler content. Overall, it is very important not only dielectric constant of the humidity sensing films but also microstructures, because they affect either the variation range of capacitance by ambient humidity or adsorption/desorption of ambient humidity onto/from the humidity sensing films.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.83-83
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• 2019

Increasing the CO₂ concentration in the atmosphere induce high temperature and rising sea levels. So the technology that capture and reuse of the CO₂ have been recently become popular. Among other methods, CRR(CO2₂ reduction reaction) is typical method of CO₂ reusing. Electrocatalyst can show more higher efficiencies in CRR than photocatalyst because it doesn't use nature source. Nowadays, finding high efficient electrocatalyst by controlling electronic (affected by stoichiometry) and geometric (affected by atomic arrangement) factors are very important issues. Mono-atomic electro-catalyst has limitations on controlling binding energy because each intermediate has own binding energy range. So the Multi-metallic electro-catalyst is important to stabilize intermediate at the same time. Carbon monoxide(CO) which is our target product and important feedstock of useful products. Au is known for the most high CO production metal. With copper, Not only gold/copper has advantages which is they have FCC packing for easily forming solid solution regardless of stoichiometry but also presence of adsorbed CO on Cu promotes the desorption of CO on Au because of strong repulsion. And gold/copper bi-metal catalyst can show high catalytic activity(mass activity) although it has low selectivity relatively Gold. Actually, multi-metallic catalyst structure control method is limited in the solution method which is takes a lot of time. In here, we introduce CTS(carbo thermal shock) method which is using heat to make MMNP in a few seconds for making gold-copper system. This method is very simple and efficient in terms of time(very short reaction time and using carbon substrate as a direct working electrode) and increasing reaction sites(highly dispersed and mixing alloy structures). Last one is easy to control degree of mixing and it can induce 5 or more metals in one alloy system. Gold/copper by CTS can show higher catalytic activity depending on metal ratio which is altered easily by changing simple variables. The ultimate goals are making CO₂ test system by CTS which can check the selectivity depending on metal types in a very short time.

• Ceramist
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• v.21 no.3
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• pp.249-269
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• 2018

In conventional MALDI-TOF mass spectrometry, analyte molecules are known to be ionized by mixing with organic matrix molecules. As the organic matrix molecules are made into small fragments, they generate unreproducible mass peaks such that MALDI-TOF mass spectrometry is nearly impossible in the low mass-to-charge (m/z) range (< 1000). Additionally, the dried sample mixed with matrix were made as inhomogeneous crystal on metal plate. When the laser radiation was made on the sample crystal, the amount of generated sample ion was observed to be quite different according to the radiation point. Therefore, the quantitative analysis was very difficult even for the sample spots at the same concentration for the conventional MALDI-TOF mass spectrometry. In this work, we present laser desorption/ionization (LDI) mass spectrometry based on solid-matrices for the quantitative analysis of small molecules in the low m/z range by using MALDI-TOF mass spectrometry: (1) Carbon based nanostructures; (2) Semiconductor based nanomaterials; (3) Metal based nanostructures.

• KSBB Journal
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• v.11 no.2
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• pp.173-180
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• 1996

The contamination of the environment by heavy metals results in a serious public health problem due to the toxicity of those pollutants even at low concentrations. Microorganisms may be used to remediate wastewaters contamlialtd with heavy metals. The waste S. cerevisiae is an inexpensive readily available source of biomass for bioremediation of wastewater. S. cerevisiae was investigated for their ability to absorb Pb. The crushed biomass of S. cerevisiae exhibited higher Pb uptake capacity than the living S. cerevisiae and the sterilized S. cerevisiae. At the same metal concentration, metal uptake per unit concentration or adsorbent decreased when the biomass concentration rises. The order of the biosorption capacity of the living S. cerevisiae was Pb>Cu>Cd=Co>Cr. When S. cerevisiae was pretreated with 0.1 M NaOH, Pb uptake was increased by 150 percent and 0.1 M HC1, 0.1 M $H_2S_O4$ solutions were efficient in the desorption of Pb. The sorption equilibrium of Pb ions can be described by the Freundlich and Langmuir models.

• Korean Journal of Materials Research
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• v.22 no.3
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• pp.159-167
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• 2012

Hydrogen is in the spotlight as an alternative next generation energy source for the replacement of fossil fuels because it has high specific energy density and emits almost no pollution, with zero $CO_2$ emission. In order to use hydrogen safely, reliable storage and transportation methods are required. Recently, solid hydrogen storage systems using metal hydrides have been under extensive development for application to fuel cell vehicles and fuel cells of MCFC and SOFC. For the practical use of hydrogen on a commercial basis, hydrogen storage materials should satisfy several requirements such as 1) hydrogen storage capacity of more than 6.5wt.% $H_2$, moderate hydrogen release temperature below $100^{\circ}C$, 3) cyclic reversibility of hydrogen absorption/desorption, 4) non toxicity and low price. Among the candidate materials, Li based metal hydrides are known to be promising materials with high practical potential in view of the above requirements. This paper reviews the characteristics and recent R&D trends of Li based complex hydrides, Li-alanates, Li-borohydrides, and Li-amides/imides.

• International Journal of Industrial Entomology and Biomaterials
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• v.26 no.1
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• pp.47-53
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• 2013

Silk sericin (SS) has been fabricated into beads using a 1 M LiCl/DMSO solvent and utilized as a heavy metal adsorbent. Among the various heavy metals, we targeted Cr(VI) for adsorption using SS beads and found that its adsorption depended on the coagulant used for the fabrication of the SS beads. When methanol was used as a coagulant, the beads had a better adsorption capacity than when ethanol was used except at pH 1. The adsorption behavior of Cr(VI) on the SS beads followed the BET isotherm. The maximum adsorption capacity was 33.76 mg/g at pH 2. The adsorption of Cr(VI) was confirmed by FT-IR and EDS analyses. Finally, the desorption was carried out using NaOH solution, and it was found that 73.19% of the adsorbed Cr(VI) could be detached.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.147-150
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• 2011

A copper-based metal organic framework (MOF) named Cu-BTC, also known as HKUST-1, was successfully synthesized by using a solvothermal method. The properties of the Cu-BTC sample were characterized with Powder X-ray diffraction (XRD) for phase structure, Thermogravimetric analysis (TGA) for thermal stability, Scanning electron microscopy (SEM) for crystal structure, and Nitrogen adsorption-desorption for pore textural structure. The analysis results displayed that the Cu-BTC sample exhibited a good crystal structure with uniform size of octahedral particles. The BET data revealed a high surface area of $1457 \;m^2g^{-1}$ and a pore volume of $0.60\; cm^3g^{-1}$. The Cu-BTCs ample was also studied for $CO_2$ adsorption and exhibited a maximum $CO_2$ adsorption capacity of 170 mg/g of the sorbent (3.8 mol/kg) at $25^{\circ}C$.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.8-16
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• 2006

The research was conducted to characterize of Rh-Pd-Pt TWC with a double-layer washcoat for gasoline vehicle. The physical characteristics on surface of catalyst were inspected by BET, SEM and TEM. The characteristics of catalytic reaction were examined by the TPD/TPR and CO-pulse chemisorption. The catalyst $6Hx(0.35\times11\times3)$ showed superior conversion performance after hydrothermal aging process, which was due to small difference of the surface area between. the fresh and the aged catalyst. The CO-chemisorption and surface area were superior in the 600 cpsi catalyst than other catalysts, this catalyst also shown the higher conversion efficiency of the exhaust emissions. From the TPR test, the conversion performance of the aged catalyst was decreased by the agglomeration and sintering of the PM and metal oxides. From the TPD result, it was found that the NO chemisorption was happed on the bottom-layer washcoat with Pd, and the NO chemisorption was re-happened on the upper-layer washcoat with Pt and Rh in the desorption process.