• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.236-240
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• 2011

In order to deposit a homogeneous and uniform ${\beta}$-SiC films by chemical vapor deposition, we demonstrated the phase stability of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure, temperature and gas composition as variables. The ${\beta}$-SiC predominant region over other solid phases like carbon and silicon was changed gradually and consistently with temperature and pressure. Practically these maps provide necessary conditions for homogeneous ${\beta}$-SiC deposition of single phase. With the thermodynamic analyses, the CVD apparatus for uniform coating was modeled and simulated with computational fluid dynamics to obtain temperature and flow distribution in the CVD chamber. It gave an inspiration for the uniform temperature distribution and low local flow velocity over the deposition chamber. These calculation and model simulation could provide milestones for improving the thickness uniformity and phase homogeneity.

• Resources Recycling
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• v.26 no.6
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• pp.97-101
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• 2017

Metal foams have a cellular structure consisting of a solid metal containing a large volume fraction of pores. In particular, open pores which are penetrable pores are necessary for industrial applications such as in high temperature filters and as support for catalysts. In this study, Fe foam with greater than 90% porosity and 2-mm pore size was successfully fabricated using a slurry coating process and the pore properties were characterized. The Fe and $Fe_2O_3$ powder mixing ratios were controlled to produce Fe foam samples with different pore sizes and porosity. First, the slurry was prepared through the uniform mixing of powders, distilled water, and polyvinyl alcohol(PVA). The amount of slurry coated with the PU foam increased with increasing $Fe_2O_3$ mixing powder ratio, but the shrinkage and porosity of the Fe foams decreased, respectively, with increasing $Fe_2O_3$ mixing powder ratio.

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.784-792
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• 2009

In this study, we investigated the unsuitable cases for the hierarchy of the curriculum in science 'teaching-learning lesson plan' which is on the web site of the each city's support center for teaching and learning and Seoul Science Park with a purpose of giving helpful data for science teachers at lessons. The investigation is limited to 'Three states of matter' unit for the 7th grade and the content elements used at analysis was the "state changes of matter", "molecule" and "molecular model". The case found for unsuitable case for the hierarchy of the curriculum was phase equilibrium, ice crystal theory, peculiar property of water, classification of solid, thermal energy and physical change at the "state changes of matter". While the "molecular model" showed molecular motion and density. On the other hand, no case was found at "molecule".

• Steel and Composite Structures
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• v.20 no.1
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• pp.167-184
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• 2016

This paper presents the details of Finite Element (FE) analysis carried out to determine the limiting deformation capacity and failure mode of Laced Steel-Concrete Composite (LSCC) beam, which was proposed and experimentally studied by the authors earlier (Anandavalli et al. 2012). The present study attains significance due to the fact that LSCC beam is found to possess very high deformation capacity at which range, the conventional laboratory experiments are not capable to perform. FE model combining solid, shell and link elements is adopted for modeling the beam geometry and compatible nonlinear material models are employed in the analysis. Besides these, an interface model is also included to appropriately account for the interaction between concrete and steel elements. As the study aims to quantify the limiting deformation capacity and failure mode of the beam, a suitable damage model is made use of in the analysis. The FE model and results of nonlinear static analysis are validated by comparing with the load-deformation response available from experiment. After validation, the analysis is continued to establish the limiting deformation capacity of the beam, which is assumed to synchronise with tensile strain in bottom cover plate reaching the corresponding ultimate value. The results so found indicate about $20^{\circ}$ support rotation for LSCC beam with $45^{\circ}$ lacing. Results of parametric study indicate that the limiting capacity of the LSCC beam is more influenced by the lacing angle and thickness of the cover plate.

• Journal of Service Research and Studies
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• v.5 no.2
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• pp.199-216
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• 2015

The current research suggests a new service research framework for service researchers and practitioners. A comprehensive and streamlined research framework is essential for rapid growth of service industry with support of academic researches. An in-depth analysis on relevant service research fremeworks and major research issues on service sector and service nature has been performed. Past and present research frameworks on service sector have been reviewed based on the nature of service and the desirability for service industry development. A new research framework has been derived and a five-section model has been suggested. The results of this research can be used for finding useful research topics in service sector. Future research is needed to develop service research as a solid and major academic field in the new economy.

• Journal of the Korean Dietetic Association
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• v.24 no.1
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• pp.1-18
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• 2018

Sustainable practices of school foodservices are gaining more attentions. The study aimed to investigate dietitians' performance levels of sustainable practices in school foodservice settings in Gyeonggi Provinces. Using a survey method was used, and data were collected from 358 participants (response rate 59.7%) to be analyzed using the SPSS program. The evaluation tool for sustainable practices of school foodservices consisted of four sections and 34 criteria with 100 points. Employment status of the respondents was as follows: nutrition teachers 40.9%, dietitians (permanent) 45.1%, and temporary position dietitians 13.2%. Dietitians' performance for sustainable practices marked 65.67 points out of 100 (performance rate 66%) and were in the following order by section: sustainable foodservice management criteria (69%), support activities (69%), planning and evaluation (68%), and outcome management (52%). Regarding sub-sections, criteria that acquired higher performance rates were labelling of food origin (99%), use of seasonal vegetables and fruits (98%), food waste management by contract dealer (98%), and planning for reducing of food waste and solid waste (91%). Meanwhile, criteria that showed the lowest scores were installing water conservation devices on equipment (19%), operating food donation programs for communities (21%), use of sensor lights for electricity conservation (24%), planning for annual energy conservation (40%), and implementation of education programs for foodservice workers on sustainable activities (42%). Performance scores differed according to school levels and working experience of dietitians, indicating that dietitians at elementary school foodservices or with work experience of 15 to 20 years showed higher performance than those at high schools or with less than 5 years of work experience (P<0.001, P<0.05). Based on the results, action plans for improvement were suggested.

• Hwankyungkyoyuk
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• v.23 no.2
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• pp.1-15
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• 2010

Ecological restoration aims to reverse the degradation of ecosystems that occurred as humans have affected landscapes. This study was conducted in part of a larger project to develop participatory ecological restoration procedures for disturbed areas in Baigdoodaegahn which is a major mountain range in the Korean Peninsula. The case of alpine farmland at Kangwon-do was selected to apply the theoretical framework of participatory restoration since the nutrient contents in alpine solid under vegetable cultivation degrade water quality in the watershed while farmers in the region are economically struggling due to imports of vegetables from China. The reciprocal model of restoration was applied to cope with interactions between human and ecosystem needs in ecological restoration. A series of environmental education and eco-tourism programs were developed and incorporated into the participatory restoration project to rebuild social-cultural aspects of the community as well as to restore the biophysically disturbed area while meeting both ecological needs and human needs. This study suggests that participatory projects will be more successful when experts support the local residents and citizens in restoration process, when leadership are developed through social learning, and when ecological, financial and social factors of restoration are integratedly considered.

• Ceramist
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• v.23 no.2
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• pp.211-230
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• 2020

Perovskite-type oxides with the nominal composition of ABO₃ can exsolve the B-site transition metal upon the controlled reduction. In this exsolution process, the transition metal emerges from the oxide lattice and migrates to the surface at which it forms catalytically active nanoparticles. The exsolved nanoparticles can recover back to the bulk lattice under oxidation treatment. This unique regeneration character by the redox treatment provides uniformly dispersed noble metal nanoparticles. Therefore, the conventional problem of traditional impregnated metal/support, i.e., sintering during reaction, can be effectively avoided by using the exsolution phenomenon. In this regard, the catalysts using the exsolution strategy have been well studied for a wide range of applications in energy conversion and storage devices such as solid oxide fuel cells and electrolysis cells (SOFCs and SOECs) because of its high thermal and chemical stability. On the other hand, although this exsolution strategy can also be applied to gas phase reaction catalysts, it has seldomly been reviewed. Here, we thus review recent applications of the exsolution catalysts to the gas phase reactions from the aspects of experimental measurements, where various functions of the exsolved particles were utilized. We also review non-perovskite type metal oxides that might have exolution phenomenon to provide more possibilities to develop higher efficient catalysts.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.6
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• pp.118-124
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• 2009

In order to know the range of install possibles of the horizontal stay without general stay, strength characteristic tests were performed for the Vertical and 80[$^{\circ}$] inclined concrete poles. From the results of one cycle strength tests, the safety factors were 2.8, 2.5 and 2.1 for the poles of general load, heavy load and high strength load, respectively. However, the crack was occurred when the bending bounds of upper part of pole was above 2[$^{\circ}$], and working load was similar to the rated load of pole at this time. Therefore, it could be concluded that the reinforcement by the installation of the stay and the support was necessary certainly, if the bending bounds of pole, which was installed on a solid foundation, are above 2[$^{\circ}$].

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.604-607
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• 2012

Solid base catalysts for biodiesel production were synthesized by impregnating basic metal species on two support materials with large specific surface area : zeolite and pyrolysis char. KL zeolite and Undaria pinnatifida char were impregnated with KOH aqueous solution and calcium nitrate solution, respectively, to enhance the basic strength. The catalysts synthesized were characterized using Hammett indicators and $CO_2$-TPD analysis. Biodiesel was produced using soybean oil and methanol over the catalysts synthesized. The content of fatty acid methyl esters was measured to evaluate the catalytic activity. Generally, the catalytic activity increased with increasing quantity of basic metal impregnated but impregnation of excessive amount of metal could cause reduction in the activity.