• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.120-126
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• 1996

In the present study, we have studied on the characteristics of BST thin films with various Ba/Sr ratios by using sol-gel method. Barium-acetate, strontium-acetate and titanium isopropoxide are used as starting materials to fabricate BST thin films by sol-gel method. The fabrication conditions are estabilished through the TG-dT analyses and XRD measurements. BST thin films with the Ba/Sr ratios of 90/10, 70/30, 50/50 and 30/70 were deposited on the Pt/Ta/SiO$_{2}$Si substrate with the estabilished sol-gel process, and their characteristics were examined. The relative permittivity and the leakage current density at 5V vary from 287 to 395 and from 2.3 to 220${\mu}$A/cm$^{2}$, respectively, with various Ba/Sr ratio. Among the films investigatd in this research, BST (70/30) thin film shows the best relative permittivity and dielectric loss of BST (70/30) thin film are 395 and 0.045, respectively and the leakage current density at 5V is 2.3${\mu}$A/cm$^{2}$.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.450-455
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• 2011

This paper presents an inverse design methodology for the cross section geometry of mold spring with a rectangular cross section as the starting material for a coiling process. The cross-sections of mold springs are universally rectangular, as the parallel sides minimize the possibility of failure under high service loads. Pre-coiled wires are initially designed to have a trapezoidal cross section, which becomes a rectangle by the coiling process. This study demonstrates a numerical exercise to predict changes in the sectional geometry in spring manufacture and to obtain the initial cross section which becomes the exact rectangle desired from the manufacturing process. Finite element analysis was carried out to calculate the sectional changes for various mold springs. Geometrical parameters were the widths at inner and outer radii, the inner and the outer corner radii, and the height. A partial least square regression analysis was carried out to find the main contributing factors for deciding initial design values. The height and the width mainly affected various initial parameters. The initial width at the inner radius was mostly affected by various specification parameters.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.337-344
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• 2022

The ecological expression of art in modern society takes the harmonious developmental relationship between man and nature as an element and combines it with the various manifestations of painting as an expression of ecological artistic development. The necessary relationship for the harmonious development of nature is accurately articulated, and the ecological changes in people are expressed in integrated materials that inspire human reflection. In the pursuit of material pleasures, mankind is neglectful and indifferent to the environment. The development of composite painting in art and ecology is a process that more reveres the harmony between man and nature as well as satisfying the creative value of the work. After systematic evaluation and research, people have engaged in various structural forms of composite art painting development in the long history of art development, focusing on the integration of environmental and ecological culture.In the process of nature education going through development, the comprehensive practical development of nature education is enhanced and efforts are made to feel new ecological art ideas and new ways of valuing environmental protection. In this paper, an observational study of eco-art will be carried out, starting from the theory of hierarchical division and analyzing the contradictory relationship between man and nature. Recognize nature, understand it and feel it through eco-art painting. The analysis of the contradictory relationship between man and nature is combined with the identification of various types of information that give value to the environmental protection public, and the combination of ecological painting and nature art to achieve an upgrade of the environmental protection idea of the value of painting.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.975-983
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• 2022

This paper presents an innovative way of integrating scheduling and project controls with the environmental impact of a construction project to track, monitor, and manage environmental emissions at the activity level. As a starting point, scheduling and project controls help monitor the status of a project to provide an assessment of the duration and sequence of activities. Additionally, project schedules can also reflect resource allocation and costs associated with various phases of a construction project. Owners, contractors and construction managers closely monitor tasks or activities on the critical path(s) and/or longest path(s) calculated through network based scheduling techniques. However, existing industry practices do not take into account environmental impact associated with each activity during the life cycle of a project. Although the environmental impact of a project may be tracked in various ways, that tracking is not tied to the project schedule and, as such, generally is not updated when schedules are revised. In this research, a Cradle to Gate approach is used to estimate environmental emissions associated with each activity of a sample project schedule. The research group has also investigated the potential determination of scenarios of lowest environmental emissions, just as project managers currently determine scenarios with lowest cost or time. This methodology can be scaled up for future work to develop a library of unit emissions associated with commonly used construction materials and equipment. This will be helpful for project owners, contractors, and construction managers to monitor, manage, and reduce the carbon footprint associated with various projects.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.321-327
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• 2012

The production of functional activated carbon materials starting from inexpensive natural precursors using environmentally friendly and economically effective processes has attracted much attention in the areas of material science and technology. In particular, the use of plant biomass to produce functional carbonaceous materials has attracted a great deal of attention in various aspects. In this study the preparation of activated carbon has been attempted from rice husks via a chemical activation-assisted microwave system. The rice husks were milled via attrition milling with aluminum balls, and then carbonized under purified $N_2$. The operational parameters including the activation agents, chemical impregnation weight ratio of the calcined rice husk to KOH (1:1, 1:2 and 1:4), microwave power heating within irradiation time (3-5 min), and the second activation process on the adsorption capability were investigated. Experimental results were investigated using XRD, FT-IR, and SEM. It was found that the BET surface area of activated carbons irrespective of the activation agent resulted in surface area. The activated carbons prepared by microwave heating with an activation process have higher surface area and larger average pore size than those prepared by activation without microwave heating when the ratio with KOH solution was the same. The activation time using microwave heating and the chemical impregnation ratio with KOH solution were varied to determine the optimal method for obtaining high surface area activated carbon (1505 $m^2$/g).

• Journal of the Korean Ceramic Society
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• v.36 no.10
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• pp.1094-1101
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• 1999

Liquid phase sintered silicon carbides were obtained by sintering of $\alpha$-SiC and $\beta$-SiC powders as starting materials at 2173K and 2273K respectively. The SiCplatelet seeds of different sizes were obtained by a repeated ball milling and sedimentation. Their mean size (d50) were 2.217 ${\mu}{\textrm}{m}$ 13.67 ${\mu}{\textrm}{m}$, 22.17${\mu}{\textrm}{m}$ respectively 6wt%Al2O3-4 wt% Y2O3 was used as the sintering additives for the liquid phase sintering. The two silicon carbides had a bimodal microstructure consisting of small matrix grains and large platelike grains when the SiCplatelet seeds were added. In the case of the $\beta$-SiC the appreciable phase transformation occurred as sintering temperature increased from 2173K to 2273K and resulted in matrix shape change from equiaxed into platelike grains. In contrast there was no shape change for the $\alpha$-SiC. The size of large grains in the $\alpha$-SiC of large grains in the $\alpha$-SiC was larger than that of the large grains in the $\beta$-SiC These results suggested that the growth of the $\alpha$-SiCplatelet in the $\alpha$-SiC matrix was more favored than that of the $\alpha$-SiCplatelet in the $\beta$-SiC matix. The three point flexural strength decreased as the added seed size increased. Fracture toughness values of samples sintered at 2273K were higher than those of samples sintered at 2173K.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3673-3679
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• 2010

This study is prepared to suggest how to develop sight-singing and ear-training program for applied music-major students. Starting from analysing the internal environment and currently existing materials, based on the questions collected for applied music-major students, integrated program for sight-singing and ear-training was considered. The use of the various kinds of classical and popular music literature, the examples of improvisation in rhythm and harmony, based on the music theories, are focal points of this program recommended here with.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.124-127
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• 1993

In this paper, the magnetic properties of Ni-Zn ferrite powders dependent on pH have been studied. Ni-Zn ferrite powders were synthesized by coprecipitation method(pH were 7. 9. 11 and 13. respetively) using FeCl$_3$$.$ 6H$_2$O, NiCl$_2$$.$6H$_2$O and ZnCl$_2$as starting materials and its powders were calcined at 1,000($^{\circ}C$). The saturated magnetizations of the Ni-Zn ferrite powders dependent on various pH. such as 7, 9, 11 and 13 were 11.44, 29.77, 69.62 and 66.75(emu/g), respetively.

• Journal of the Korean Ceramic Society
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• v.27 no.3
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• pp.394-400
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• 1990

Mullite and cordierite were prepared by the sol-gel route. Boehmite, fumed silica and Mg(NO3)2$.$6H2O were their starting materials. Mullite and cordierite powder were mixed by various weight percent. These mixed sols were ball-milled for 48hrs, dried at 100$^{\circ}C$, pressed, cold isostatic pressed and sintered at 1490$^{\circ}C$ for 2hrs. Mullite-cordierite composites sintered at 1490$^{\circ}C$ for 2hrs had>98% of theoretical density. Bending strength of the sintered bodies were 329-249MPa, dielectric constant 7.1-6.7 at 1MHz and thermal expansion coefficient at 800$^{\circ}C$ was matched with Si in the range of 30-35wt% cordierite.

• Journal of the Korean Ceramic Society
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• v.34 no.11
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• pp.1113-1120
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• 1997

The 2, 4, 6 and 8mol% Y2O3 doped-ZrO2 powders (20 kinds) with the addedtion of Al2O3 upto 8wt% were prepared by coprecipitation method using the zirconium oxyacetate, yttrium chloride and aluminum nitrate as starting materials. The coprecipitated powders were characterized by XRD, TG-DTA, FT-IR and SEM. The sintering properties of zirconia-alumina composites prepared by 2YSZ and 8YSZ powders containing various Al2O3 contents were also investigated. With increasing the yttria stabilizer contents, the amount of exothermic heat for zirconia crystallization decreased. And it was confirmed that the crystallizing temperature of coprecipitated zirconia powders increased and the crystallization process occurred in a wide temperature range, as Al2O3 content increased in 8YSZ.