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Pohang, South Korea

An C.M.,Colorado School of Mines | Song J.-H.,RIST | Kang I.,Colorado School of Mines | Sammes N.,Colorado School of Mines
Journal of Power Sources | Year: 2010

In this paper, a graded Ni/YSZ cermet anode, an 8 mol.%YSZ electrolyte, and a lanthanum strontium manganite (LSM) cathode were used to fabricate a solid oxide fuel cell (SOFC) unit. An anode-supported cell was prepared using a tape casting technique followed by hot pressing lamination and a single step co-firing process, allowing for the creation of a thin layer of dense electrolyte on a porous anode support. To reduce activation and concentration overpotential in the unit cell, a porosity gradient was developed in the anode using different percentages of pore former to a number of different tape-slurries, followed by tape casting and lamination of the tapes. The unit cell demonstrated that a concentration distribution of porosity in the anode increases the power in the unit cell from 76 mW cm-2 to 101 mW cm-2 at 600 °C in humidified hydrogen. Although the results have not been optimized for good performance, the effect of the porosity gradient is quite apparent and has potential in developing superior anode systems. © 2009 Elsevier B.V. All rights reserved. Source


Seok S.-H.,RIST | Seok S.-H.,Tohoku University | Miki T.,Tohoku University | Hino M.,Tohoku University | Hino M.,Hokkaido Polytechnic College
ISIJ International | Year: 2011

The Ti deoxidation equilibrium of Fe-Ni, Fe-Cr and Fe-Cr-Ni alloys saturated with 'Ti3O5' and Ti2O3 phase was clarified in previous researches. Solubility of Fe, Cr and/or Ni oxides in 'Ti3O5' phase equilibrated with liquid Fe-Ni, Fe-Cr and Fe-Cr-Ni alloys at 1823 K to 1923 K were measured by SEM-EDS. It was confirmed that the solubility of Fe, Cr and/or Ni oxide in 'Ti3O 5' phase at low Ti content increase with decrease of Ti content in alloys. Titanium content that dissolution of Fe, Cr and/or Ni oxide into 'Ti3O5' phase becomes apparent increases with increase of Cr and/or Ni content of the alloys. The activity of Ti deoxidation product, 'Ti3O5' phase, equilibrated with Fe-Ni, Fe-Cr and Fe-Cr-Ni alloys was also evaluated by Redlich-Kister type polynomial. Equilibrium between Ti and O at low Ti content of those alloys was analyzed using the activity of 'Ti3O5' phase. © 2011 ISIJ. Source


Kwon Y.B.,Yeungnam University | Kim G.D.,RIST | Kwon I.K.,Kangwon National University
Steel and Composite Structures | Year: 2014

This paper describes a series of compression tests performed on cold-formed steel channel sections with perforations in the web (thermal studs) fabricated from a galvanized steel plate whose thickness ranged from 1.0 mm to 1.6 mm and nominal yield stress was 295 MPa. The structural behavior and performance of thermal studs undergoing local, distortional, or flexural-torsional buckling were investigated experimentally and analytically. The compression tests indicate that the slits in the web had significant negative effects on the buckling and ultimate strength of thin-walled channel section columns. The compressive strength of perforated thermal studs was estimated using equivalent solid channel sections of reduced thickness instead of the studs. The direct strength method, a newly developed and adopted alternative to the effective width method for designing cold-formed steel sections in the AISI Standard S100 (2004) and AS/NZS 4600 (Standard Australia 2005), was calibrated to the test results for its application to cold-formed channel sections with slits in the web. The results verify that the DSM can predict the ultimate strength of channel section columns with slits in the web by substituting equivalent solid sections of reduced thickness for them. Copyright © 2014 Techno-Press, Ltd. Source


Lim Y.-I.,Hankyong National University | Choi J.,SK Biotek | Moon H.-M.,Daesung Industrial Co. | Kim G.-H.,RIST
Korean Chemical Engineering Research | Year: 2016

Linze-Donawitz gas (LDG) adjunctively produced in the steel mill contains over 60% of CO. Two processes that recover high purity CO from LDG were considered: COSORB and CO-Pressure swing adsorption (PSA). This study aimed to decide which one is more economically feasible than the other by techno-economic analysis (TEA). From the technical point of view of TEA, the process flow diagram (PFD) was constructed, the mass and energy balances were calculated, and the equipment type and size were determined in order to estimate the total capital investment (TCI) and the total production cost (TPC). From the economic point of view of TEA, economic performance such as return on investment (ROI) and payback period (PBP) was evaluated, and the sensitivity analysis was carried out to identify key factors influencing ROI and PBP. It was found that CO-PSA is more economically feasible due to higher ROI and lower PBP. The CO price highly influenced ROI and PBP. Source


Kim D.-H.,Super Tall Building Research Team | Lee S.-E.,Super Tall Building Research Team | Kim J.-H.,RIST | Yu S.-H.,POSCO
SEAISI Quarterly (South East Asia Iron and Steel Institute) | Year: 2013

HSA800 is a new 800MPa high strength steel plate for building structures developed by POSCO and RIST in 2011 combining the advantages of SN and TMCP steels. It obtained the certification of Korean Industrial Standards (KS D 5994) in October 2011. It has upper and lower bounds for yield (Fy) and tensile (Fu) strength as of 650-770MPa and 800-950MPa, respectively, with yield ratio (Fy/Fu) as of 0.85 below so as to make steel quality more reliable and enhance the seismic resistance of structures. Microalloys such as Nb, V and Ti affecting base metal's grain refinement and thermo mechanical control process (TMCP) were added to increase yield and tensile strengths of the basic material. As made by TMCP, it has a good weldability without increasing carbon percentage. To evaluate the cost-effectiveness of the HSA800, two different analytical models of an ultra high-rise building artificially developed in accordance with typical tall building configurations were analyzed. The result shows that the high-strength steel model could save approximately 40% steel quantity compared to that of the normal strength steel model. HSA800 is being applied to the mega steel structural members of the Lotte World Tower, a first ultra high-rise building in South Korea having 555m height (124F). By reducing total steel quantity, it will also contribute to reduce CO2 emissions. Source

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