• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.693-701
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• 2016

Steam gasification of low rank coals is possible at relatively low temperature and low pressure, and thus shows higher efficiency compared to high rank coals. In this study, the gasification reactivity of four different Indonesian low rank coals (Samhwa, Eco, Roto, Kideco-L) was evaluated in $T=700-800^{\circ}C$. The low rank coals containing $53.8{\pm}3.4$ wt% volatile matter in proximate analysis and $71.6{\pm}1.2$ wt% carbon in ultimate analysis showed comparable gasification reactivity. In addition, $K_2CO_3$ catalyst rapidly accelerated the reaction rate at $700^{\circ}C$, and all of the coals were converted over 90% within 1 hour. The XRD analysis showed no significant difference in carbonization between the coals, and the FT-IR spectrum showed similar functional groups except for differences due to moisture and minerals. TGA results in pyrolysis ($N_2$) and $CO_2$ gasification atmosphere showed very similar behavior up to $800^{\circ}C$ regardless of the coal species, which is consistent with the steam gasification results. This confirms that the indirect evaluation of the reactivity can be made by the above instrumental analyses.

• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.16-25
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• 2016

In severe loss of coolant accidents (LOCA), similar to those experienced at Fukushima Daiichi and Three Mile Island Unit 1, the zirconiumalloy fuel claddingmaterials are rapidlyheateddue to nuclear decay heating and rapid exothermic oxidation of zirconium with steam. This heating causes the cladding to rapidly react with steam, lose strength, burst or collapse, and generate large quantities of hydrogen gas. Although maintaining core cooling remains the highest priority in accident management, an accident tolerant fuel (ATF) design may extend coping and recovery time for operators to restore emergency power, and cooling, and achieve safe shutdown. An ATF is required to possess high resistance to steam oxidation to reduce hydrogen generation and sufficient mechanical strength to maintain fuel rod integrity and core coolability. The initiative undertaken by Electric Power Research Institute (EPRI) is to demonstrate the feasibility of developing an ATF cladding with capability to maintain its integrity in $1,200-1,500^{\circ}C$ steam for at least 24 hours. This ATF cladding utilizes thin-walled Mo-alloys coated with oxidation-resistant surface layers. The basic design consists of a thin-walled Mo alloy structural tube with a metallurgically bonded, oxidation-resistant outer layer. Two options are being investigated: a commercially available iron, chromium, and aluminum alloy with excellent high temperature oxidation resistance, and a Zr alloy with demonstratedcorrosionresistance.Asthese composite claddings will incorporate either no Zr, or thin Zr outer layers, hydrogen generation under severe LOCA conditions will be greatly reduced. Key technical challenges and uncertainties specific to Moalloy fuel cladding include: economic core design, industrial scale fabricability, radiation embrittlement, and corrosion and oxidation resistance during normal operation, transients, and severe accidents. Progress in each aspect has been made and key results are discussed in this document. In addition to assisting plants in meeting Light Water Reactor (LWR) challenges, accident-tolerant Mo-based cladding technologies are expected to be applicable for use in high-temperature helium and molten salt reactor designs, as well as nonnuclear high temperature applications.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.95-101
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• 2016

For a natural gas steam reforming, comparative studies of the performance in a conventional packed-bed reactor and a membrane reactor, a new conceptual reactor consisting of a reactor with series of hydrogen separation membranes, have been performed. Based on experimental kinetics reported by Xu and Froment, a process simulation model was developed with Aspen $HYSYS^{(R)}$, a commercial process simulator, and effects of various operating conditions like temperature, $H_2$ permeance, and Ar sweep gas flow rate on the performance in a membrane reactor were investigated in terms of reactant conversion and $H_2$ yield enhancement showing improved $H_2$ yield and methane conversion in a membrane reactor. In addition, a preliminary cost estimation focusing on natural gas consumption to supply heat required for the system was carried out and feasibility of possible cost savings in a membrane reactor was assessed with a cost saving of 10.94% in a membrane reactor.

• Journal of Engineering Education Research
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• v.23 no.5
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• pp.68-75
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• 2020

In order to cultivate the talents acquired in the fourth industrial revolution, developed countries' government are actively engaged in the campaigns encouraging K-12 students to participate in the maker movement. Maker education is regarded as one possible solution based on high tech in the era of the 4th Industrial Revolution, and it is spreading widely along with STEM education. In South Korea, STEAM education was actively conducted nationwide, and since 2017, STEAM and maker education have been linked showing mutual development. However, compared to STEAM education linked to the curriculum, comparison and activity-based research on maker education for teenagers is still insufficient. Therefore, this study aimed to suggest implications for STEAM education and maker education by analyzing the motivation of Korean youth to participate in maker activities. The subjects of this study are high school students who participated in maker education programs in student community for the first time in Korea. In this study, students were classified into engineering-related career group and non-engineering-related career groups based on their career intentions, and the motivation and understanding of participation in maker activities were compared. As a result of the study, male students participated more in maker education community activities than female students, and the engineering-related career group had a higher intention to participate in games, outdoor activities, IT equipment, digital production, and electrical/electronic production activities than the non-engineering-related career group. In addition, in the fields of handicraft/art, home baking, installing, and horticultural agriculture, there was no difference in the intention of participate in the engineering-related career group and the non-engineering-related career group. It was found that the engineering-related career group believed that there was a strong relationship between the maker education community activity, career exploration and future career choice, while the non-engineering-related career group believed that the relationship is less strong. It was also found that the engineering-related career group was participating more actively in the maker activity than the other group.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.113-115
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• 2014

Lab scale simulated steam assisted gravity drainage (SAGD) process devices were used to investigate the effect of inorganic additives for the bitumen recovery from oil sand. An extra heavy oil similar with bitumen and 1.5 mm diameter of the glass bead instead of clay was mixed to simulate the oil sand. In addition, $FeO_X$ synthesized from the inorganic process was introduced as an inorganic additive for improving the recovery. Finally, the steam heat transfer rate of approximately 40% following the introduction of inorganic additives which also increased the recovery rate by about 30%.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.695-706
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• 2018

This study was conducted to investigate the effect of a steam chamber type on the ruminal fermentable characteristics and nutrient degradabilities of corn flakes in Hanwoo. Three Hanwoo equipped with a ruminal fistula were used as experimental animals. There were two treatments: Corn flake using a steam chamber (CFSC, 1.0 atm - $100^{\circ}C$ 96 min) or corn flake using a pressurized steam chamber (CFPSC, 1.5 atm - $111^{\circ}C$ 12 min), respectively. In the in vitro trial, the ruminal pH was significantly lower in the CFPSC than in the CFSC (p < 0.01). The ammonia concentration was increased by 14.1% in the CFPSC compared to the CFSC (p < 0.05). The concentration of acetic acid was higher in the CFSC than in the CFPSC (p < 0.01). The concentrations of propionate, butyrate and total-VFA at 24 and 48 h were higher in the CFPSC than in the CFSC (p < 0.05). In the in situ trial, the degradability of dry matter was significantly higher in the CFSC than in the CFSC (p < 0.01). In addition, the degradabilities of starch and crude protein were significantly higher in the CFSC than in the CFSC (p < 0.01). Thus, the present results indicate that the pressurized steam chamber could be recommended to improve the feed value of corn flake according to the increase in the starch degradability and volatile fatty acid production.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.103-106
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• 2000

The effects of replacement level, curing method and chemical admixtures were investigated in the cement-fly ash paste. The strength of cement-fly ash paste is lower than that of controlled cement paste only and the differences increase with replacement level. However, in steam curing, strength of cement-fly ash pastes is improved, especially, at early ages. In order to improve early strength, the use of $Na_2SO_4$in cement-fly ash paste increases the quality of concrete. In addition, improvement of strength of concrete including 30% of fly ash can be obtained and achieves the highest strength compared to other concrete mixtures.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.102-105
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• 2001

The spring back taking place after the coiling process of steam generator tube leads to the dimensional inaccuracy. In order to reduce the spring back, tension force was applied to the one end of the tube during forming. In this work, parametric study using FEM was performed to find the appropriate magnitude of tension force. The force that induces minimum suing back was found by simultaneously taking account of suing back amount, cross-sectional ovality, and thickness of the tube wall after deformation. In addition, stress relieving by heat treatment was also simulated as an alternative to the former method. The latter was found to be more effective under the given constraints.

• Transactions of Materials Processing
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• v.11 no.3
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• pp.238-245
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• 2002

The spring back taking place after the coiling process of steam generator tube leads to the dimensional inaccuracy. In order to reduce the spring back, tension force was applied to the one end of the tube during forming. In this work, parametric study using FEM was performed to find the appropriate magnitude of tension force. The force that induces minimum spring back was found by simultaneously taking account if spring back amount, cross-sectional ovality, and thickness of the tube wall after deformation. In addition, stress relieving by heat treatment was also simulated as an alternative to the former method. The latter was found to be more effective under the given constraints.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.273-279
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• 2008

The purpose of this study is not only to evaluate thermal performance but also to find the stress behavior of heat transfer tubes under the part load operation in Heat Recovery Steam Generator. Flow analysis was performed to know the behavior of exhaust gas from gas turbine and thermal performance was calculated using distribution of hot exhaust velocity. In addition, tubes temperature during operation were gathered from actual plant to verify the uneven flow distribution under part load operation. Stress analysis was performed using tubes temperature data gathered from actual plant under both part and full load operations to know the stress behavior of tubes.