• 대한화학회지
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• 제68권2호
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• pp.87-92
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• 2024

The commercialization of rechargeable metal-air batteries is extremely desirable but designing stable oxygen reduction reaction (ORR) catalysts with non-noble metal still has faced challenges to replace platinum-based catalysts. The nonnoble metal catalysts for ORR were prepared to improve the catalytic performance and stability by the thermal decomposition of ZIF-8 with optimum cobalt loading. The porous carbon was obtained by the calcination of ZIF-8 and different loading amounts of Co nanoparticles were anchored onto porous carbon forming a Co/PC catalyst. Co/PC composite shows a significant increase in the ORR value of current and stability (500 h) due to the good electronic conductive PCN support and optimum cobalt metal loading. The significantly improved catalytic performance is ascribed to the chemical structure, synergistic effects, porous carbon networks, and rich active sites. This method develops a new pathway for a highly active and advantageous catalyst for electrochemical devices.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.78.1-78.1
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• 2010

The metal-supported solid oxide fuel cell (SOFC) was studied. Hydrocarbon fueled operation is necessary to make SOFC system. Different operating characteristics for metal-supported SOFC are used than for conventional ones as hydrocarbon fueled operation. Metal-supported SOFC was successfully fabricated by a high temperature sinter-joining method and the cathode was in-situ sintered. Synthetic gas, which is compounded as the diesel reformate gas composition and low hydrocarbons was completely removed by the diesel reformer. Metal-supported SOFC with synthetic gas was operated and evaluated and its characteristics analyzed. Button cell and $5{\times}5cm^2$ single stack were mainly operated and analyzed. Long-term operation using diesel reformate shows degradation, and degradation analysis was completed in the view of metal oxidation. Solution to increase stability of long-term operation was tried in the way of materials and operating conditions. Finally, $5{\times}5cm^2$ metal-supported single stack using synthetic gas was operated for 1000 hours under the modified condition.

• 한국생산제조학회지
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• 제21권3호
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• pp.408-414
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• 2012

Screen printing is a printing method that uses a woven mesh to support an ink-blocking stencil by transferring ink or other printable materials in order to form an image onto a substrate. Recently, the screen printing method has applied to micro-electronic packaging by using solder paste as a printable material. For the screen printing of solder paste, metal masks containing a number of micro-holes are used as a stencil material. The metal mask undergoes deformation when it is installed in the screen printing machine, which results in the deformation of micro-holes. In the present study, finite element (FE) analysis was performed to predict the amount of deformation of a metal mask. For an efficient calculation of the micro-holes of the metal mask, the sub-domain analysis method was applied to perform FE analyses connecting the global domain (the metal mask) and the local domain (micro-holes). The FE analyses were then performed to evaluate the effects of slot designs on the deformation characteristics, from which more uniform and adjustable deformation of the metal mask can be obtained.

• 한국표면공학회지
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• 제49권3호
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• pp.286-300
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• 2016

Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.443-446
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• 2006

Carbon-supported Platinum (Pt) is the potential electro-catalyst material for anodic and cathodic reactions in fuel cell. Catalytic activity of the metal strongly depends on the particle shape, size and distribution of the metal in the porous supportive network. Conventional preparation techniques based on wet impregnation and chemical reduction of the metal precursors often do not provide adequate control of particle size and shape. We have proposed a novel route for preparing nano sized Pt colloidal particles in solution by oxidation of ethylene glycol. These Pt nano particles were deposited on large surface area carbon support. The process of nano Pt colloid formation involves the oxidation of solvent ethylene glycol to mainly glycolic acid and the presence of its anion glycolate depends on the solution pH. In the process of colloidal Pt formation glycolate actsas stabilizer for the Pt colloidal particle and prevents the agglomeration of colloidal Pt particles. These mono disperse Pt particles in carbon support are found uniformly distributed in nearly spherical shape and the size distribution was narrow for both supported and unsupported metals. The average diameter of the Pt nano particle was controlled in the range off to 3 nm by optimizing reaction parameters. Transmission electron microscopy, CV and RRDE experiments were used to compliment the results.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3281-3289
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• 2011

The materials composed of the 3d series transition metals are introduced into the hydrocarbon steam-reforming reaction in order to enhance the $H_2$ production and abruptly depress the catalytic deactivation resulting from the strong sintering between the Ni component and the ${\gamma}-Al_2O_3$ support. The conventional impregnation method is used to synthesize the Ni/3d series metal/${\gamma}-Al_2O_3$ materials through the sequentially loading Ni source and the 3d series metal (Ti, V, Cr, Mn, Fe, Co, Cu, and Zn) sources onto the ${\gamma}-Al_2O_3$ support. The Mnloaded material exhibits a significantly higher reforming reactivity than the conventional Ni/${\gamma}-Al_2O_3$ and the other Ni/3d series metal/${\gamma}-Al_2O_3$ materials. Particularly the addition of Mn selectively improves the $H_2$ product selectivity by eliminating the formation of $CH_4$ and CO. The $H_2$ production is maximized at a value of 95% over Ni(0.3)/Mn(0.3)/${\gamma}-Al_2O_4$(1.0) with a butane conversion of 100% above $750^{\circ}C$ for up to 55 h.

• 한국진공학회지
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• 제18권4호
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• pp.281-287
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• 2009

본 연구에서는 고진공 조건에서 열기화 증착 방법으로 산화막으로 덮인 Mg 리본(MgO/Mg) 위에 Pd을 증착하였다. 고진공 속에서 만든 시료의 전자구조를 in-situ X-선 광전자 분광법 (XPS)을 통하여 분석하였고, 분석 후, FE-SEM을 통해 증착량의 증가에 따른 표면구조의 변화를 확인하였다. Pd 증착량이 1 나노미터 (nm) 이하인 경우에는 증착량 증가에 따른 Pd 나노입자 크기의 증가를 확인하였으며, Pd을 1 nm 이상의 두께로 증착시킨 경우에는 Pd 입자들의 뭉침에 의해 얇은 필름이 형성됨을 관찰하였다. Pd과 기판사이의 전하이동에 의하여 산화물/금속 계면의 Pd 원자들은 부분적으로 양전하를 띔을 확인하였다.

• Korean Chemical Engineering Research
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• 제59권2호
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• pp.174-179
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• 2021

Recently, hybrid coal research is underway to upgrade low-grade coal. The hybrid coal is made by mixing low-grade coal with bioliquids such as molasses, sugar cane, and lignin. In the case of lignin used here, a large amount of lignin is included in the wastewater of the papermaking process, and thus, research on hybrid coal production using the same is attracting attention. However, since a large amount of metal ions are contained in the lignin wastewater from the papermaking process, substances that corrode the generator are generated during combustion, and the amount of fly ash is increased. To solve this problem, it is essential to remove metal ions in the lignin wastewater. In this study, metal ions were removed by ion exchange with a alumina hollow fiber membrane coated with K-Phillipsite (K-PHI) zeolite. The alumina hollow fiber membrane used as the support was prepared by the nonsolvent induced phase separation (NIPS) method, and K-PHI seeds were prepared by hydrothermal synthesis. The prepared K-PHI seed was seeded on the surface of the support and coated by secondary growth hydrothermal synthesis. The characteristic of prepared coating membrane was analyzed by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDX), and the concentration of metal ions before and after ion exchange was measured by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The extraction amount of K+ is 86 mg/kg, and the extraction amount of Na+ is 54.9 mg/kg. Therefore, K-PHI zeolite membrane has the potential to remove potassium and sodium ions from the solution and can be used in acidic lignin wastewater.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.487-490
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• 2008

Temperature programmed oxidation (TPO) is used to characterize coke species deposited on commercial nickel catalyst, C11-PR during propane pre-reforming. Propane pre-reforming performed under various condition, S/C from 1.5 to 2.5 and temperature from $350^{\circ}C$ to $450^{\circ}C$. There are three kinds of coke species detected by TPO: (i) reactive coke, (ii) coke deposited on metal site and (iii) coke deposited on acid support. Coke deposited on metal and support are minimized although reactive coke is generated at temperature of $400^{\circ}C$ and S/C of 2.0. Reactive coke is expected to remove easily below temperature of $200^{\circ}C$. Therefore, optimized pre-reforming condition for propane is $400^{\circ}C$ and S/C of 2.0.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 추계학술발표회논문집(1)
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• pp.289-294
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• 1996

Feasibility study on conceptual design tool for liquid metal reactor has been conducted to optimize the thermohydraulic and neutronic design parameters. To accomplish this task the neutronic code PRISM, fuel performance code and scaling method have been included into the conceptual design support system. ALMR(PRISM 303MWe) has been adopted as the reference plant and principally according to the power level, conceptual design parameters are optimized so that energy balance and neutronics balance seem to be satisfied. This paper presents only the results of optimization on primary system including the IHX system.