• The Journal of the Petrological Society of Korea
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• v.21 no.4
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• pp.405-413
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• 2012

This study demonstrates the consolidation effect of ethylsilicate consolidants considering material characteristics and weathering degree of Samneunggyeseongakyukjonbul(rock-carved Yukjonbul Buddha in Samneung Valley) in Namsan, Gyeongju. The buddha statue is composed of alkali feldspar granite and contains numerous sets of joint with exfoliation and granular disintegration, therefore the statue is necessary to be treated for surface strength. The laboratory and in-situ tests of consolidation effect showed more increase of ultrasonic velocity that KSE 300, a relatively highly concentrated consolidant, performed more increase of ultrasonic velocity and decrease of porosity than others after treatments in weathered granite. And the consolidated rock with OH 100 was more resistant to salt weathering. For the buddha statues, KSE 300 is more applicable to enhance surface strength because it showed higher consolidation effect for long term than OH 100 and the statues has not been weathered by salts.

• Clean Technology
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• v.18 no.2
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• pp.177-182
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• 2012

Mesoporous anatase $TiO_2$ nanoparticles have been synthesized by a hydrothermal method using a tri-block copolymer as a soft template. The resulting $TiO_2$ materials have a high specific surface area of $230\;m^2/g$, a predominant pore size of 6.8 nm and a pore volume of 0.404 mL/g. The electrochemical properties of mesoporous anatase $TiO_2$ for lithium ion battery (LIB) anode materials have been investigated by typical coin cell tests. The initial discharge capacity of these materials is 240 mAh/g, significantly higher than the theoretical capacity (175 mAh/g) of LTO ($Li_4Ti_5O_{12}$). Although the discharge capacity decreases with the C-rate increase, the mesoporous $TiO_2$ is very promising for LIB anode because the surface for the Li insertion is presented significantly with mesopores. Nitrogen doping has a certain effect to control the capacity decrease by improving the electron transport in $TiO_2$ framework.

• The Korean Journal of Mycology
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• v.39 no.3
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• pp.217-222
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• 2011

Job's tears (Coix lacryma-jobi) is native to East Asia, and grains of the plant are used as health food and medicinal material. Head blight symptoms of the plant were frequently observed during disease surveys in Korea from 2006 to 2008. The symptoms were characterized as discoloration of husks, and subsequently inside of mature grains were shriveled or emptied. One hundred fifty nine isolates of Fusarium species were obtained from the disease symptoms of the plant collected from several locations in the country. Out of the isolates, the most frequently isolated Fusarium species were F. graminearum (34%), F. proliferatum (14.5%), F. verticillioides (10.1%), F. equiseti (6.9%), and F. fujikuroi (6.3%). Other Fusarium species isolated were F. subglutinans, F. semitectum, F. poae, and F. sporodochioides. Elongation factor 1 alpha gene sequences of the isolates were used for phylogenetic analysis. Analyses of the sequences revealed that the isolates were confirmed to be identical with each reference species of NCBI GenBank. Pathogenicity tests showed that F. graminearum, F. proliferatum and F. verticillioides were strongly virulent to grains of Job's tears. The present study is the first report of head blight of Job's tears caused by Fusarium species in Korea.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.199-209
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• 2010

Coal gasification technology in the sector of domestic clean coal technologies is being into the limelight since recent dramatic rise of international oil price. In this study, we used a low rank coal from Inner Mongolia, China as a starting material for gasification. Various properties including optical, mineralogical, X-ray spectroscopic, X-ray diffraction, and drying property were measured and tested in order to estimate the suitability of the coal to gasification. The coal was identified as a brown coal of lignite group from the measurement of vitrinite reflectance. The coal has very low slagging and fouling potentials, and the ignition temperature is about $250^{\circ}C$. The major impurities consist of quartz, siderite, and clay minerals. Additionally, the coal had moisture content above 28%. Tests for finding effective drying method showed that the microwave drying is more effective than thermal drying.

• Journal of Conservation Science
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• v.32 no.4
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• pp.491-500
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• 2016

Fog is atmospheric in which tiny drops of water vapor are suspended in the air near the ground. Its form, occurrence, etc., change according to the temperature, relative humidity, wind and geographical features of the space around it. In particular, fog tends to occur near a source of water because of temperature and relative humidity difference. These days, climate change is increasingly affecting the occurrence of fog. Therefore the purpose of this study was to investigate how fog affects materials that are part of our cultural properties through outdoor exposure tests and artificial degradation. The degradation evaluation of materials as a function of fog occurrence frequency, showed that the color of metals changed noticeably, whereas dyed silk and Dancheong showed degradation on the surface and color differences but no particular tendencies. Therefore, damage prediction by color differences as a function of fog occurrence frequency was based on metal samples, which showed constant color differences. Through a comparison of the predictive value and color difference by outdoor exposure, the accuracy and applicability of the damage prediction formula was confirmed. If a more complex damage prediction formula is created, it is expected that prediction of the degree of material damage in the field would be possible.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.3
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• pp.23-29
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• 2013

Development of flexible electronic devices has primarily focused on printing technology using organic materials. However, organic-based flexible electronics have several disadvantages, including low electrical performance and long-term reliability. Therefore, we fabricated nano- and micro-thick silicon film attached to the polymer substrate using transfer printing technology to investigate the feasibility of silicon-based flexible electronic devices with high performance and high flexibility. Flexibility of the fabricated samples was investigated using bending and stretching tests. The failure bending radius of the 200 nm-thick silicon film attached on a PI substrate was 4.5 mm, and the failure stretching strain was 1.8%. The failure bending radius of the micro-thick silicon film attached on a FPCB was 2 mm, and the failure strain was 3.5%, which showed superior flexibility compared with conventional silicon material. Improved flexibility was attributed to a buffering effect of the adhesive between the silicon film and the substrate. The superior flexibility of the thin silicon film demonstrates the possibility for flexible electronic devices with high performance.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.6
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• pp.903-910
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• 2007

In order to make acquire a potential use for Opuntia humifusa as a natural functional food material, this study was performed to determine the quality properties of Jeung-pyun made with added Opuntia humifusa, or prickly pear powder. According to an analysis of its major components, we found that the prickly pear powder consisteds of nitrogen-free extracts (71.85%) and crude fiber (11.20%). Greater additions of prickly pear powder had resulted in significantly lower pH in the of Jeung-pyun. According to measurements on the degree of Jeung-pyun gelatinization, by means of ${\beta}$-amylase, greater additions of prickly pear powder led to the higher levels of isolated maltose, indicating that the gelatinization degree of the Jeung-pyun became higher. Also, samples with higher concentrations of prickly pear powder had a tendency toward lower water content, which allowed us to expect a longer storage duration for the Jeung-pyun. In the textural property tests the Jeung-pyun that had less hardness and greater adhesiveness (p<0.05) than the control group as the content of prickly pear powder became higher. Also, the Jeung-pyunhad lower gumminess and chewiness than the control group as the content of prickly pear powder became higher. Therefore, it is possible to prepare relatively soft Jeung-pyun using prickly pear powder. For the color differences of the Jeung-pyun samples, lower L- values, and higher a- and b -values (p<0.05) presented as the addition level of prickly pear powder became higher. According to SEM observations of the Jeung-pyun, the added prickly pear powder addition groups generally showed a smaller and more inconsistent pore size, but higher porosity, than the control group. According to sensory analyses of the Jeung-pyun, the P2 group scored highest for color item, and the P4 group generated the fermented scent. Higher additions content of prickly pear powder led to the lower score, but higher scores for adhesiveness. Finally, the P2 group achieved the highest score for overall taste.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.449-456
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• 2002

Recently, the application of high strength and high performance concrete has been gradually increased as an important construction material for high rise and huge scaled construction. However, high performance concrete has undesirable characteristics of spalling subjected to high temperature due to its dense microstructure content. A spalling by fire brings surface failure and falling off concrete member. It is considered that spalling by fire should be taken into account for the safety of the concrete structure under fire. Therefore, in this paper, tests are carried out using high performance concrete containing polypropylene(PP) fiber in order to improve the fire resistance performance. PP fiber contents and member sizes are varied. According to experimental results, as for the influence of PP fiber contents, all the test specimens without PP fiber show entire failure in W/C of 35％, while they show nearly sound shape except some kinds of surface fracture in W/C of 55％. When PP fiber is contained more than 0.07％, favorable prevention effects of spatting by fire are obtained. As for the effects of test specimens size, it tends to increase the possibilities of spatting by fire as test specimens become larger. And spatting by fire at the edge of test specimens occurs more frequently than at the surface of test specimens. Residual compressive and tensile strength shows 45∼65 ％ of its original strength at W/C of 35％, and 30∼40％ at W/C of 55 ％.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.743-752
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• 2007

Statement of problem. The aims of the study were to evaluate the effect of current surface conditioning methods on the bond strength of a resin composite luting cement bonded to ceramic surfaces and to identify the optimum cement type. Material and methods. The sixty zirconia ceramic specimens(10 per group) with EVEREST milling machine and 60 tooth block were made. The zirconia ceramic surface was divided into two groups according to surface treatment: (1) airborne abrasion with $110{\mu}m$ aluminum oxide particles; (2) Rocatec system, tribochemical silica coating. The zirconia ceramic specimens were cemented to tooth block using resin cements. The tested resin cements were Rely X ARC, Panavia F and Superbond C&B. Each specimen was mount in a jig of the universal testing machine for shear strength. The results were subjected to 2-way ANOVA and Post hoc tests was performed using Tukey, Scheffe, and Bonferroni test. Results. The mean value of shear bond strength(MPa) were as follows: $$RelyXARC(+Al_2O_3),5.35{\pm}1.69$$; $$RelyXARC(+Rocatec),8.50{\pm}2.13$$; $$PanaviaF(+Al_2O_3),9.58{\pm}1.13$$; $$PanaviaF(+Rocatec),12.98{\pm}1.71$$; $$SuperbondC&B(+Al_2O_3)8.27{\pm}2.04$$; $$SuperbondC&B(+Rocatec),14.46{\pm}2.39$$. There was a significant increase in the shear bond strength when the ceramic surface was subjected to the tribochemical treatment(Rocatec 3M) in all cement groups(P<0.05). Bonding strengths of cements applied to samples treated with $Al_2O_3$ were compared; Rely X ARC showed the lowest values, whereas Panavia F cement showed higher value than that of Superbond C&B group with no statistical significance. When the bond strength of cements with of Rocatec treatment was compared, Rely X ARC showed lowest values. Overall, it was apparent that tribochemical treated Super-Bond possessed higher mean bond strength (14.46MPa; P<0.05) than that of Panavia F cement group with no significance. Conclusions. Silica coating followed silanization(Rocatec treatment) increase the bond strength between resin cement and zirconia ceramic. Panavia F containing phosphate monomer and Superbond C&B comprised of 4-META tend to bond chemically with zirconia ceramic, thus demonstrating higher bond strength compared to BisGMA resin cement. Superbond C&B has shown to have highest value of bonding strength to zirconia ceramic after Rocatec treatment compared to other cement.

• Journal of The Korean Association For Science Education
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• v.33 no.6
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• pp.1139-1153
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• 2013

Misconceptions are one of the most important and long-lasting studied themes on science education. It is because their nature is obstinate and settled as well as they corrupt students' understanding of science concepts. This study examines whether preservice elementary school teachers enrolled in biology teaching material research course changed positively on science teaching efficacy and correcting life science misconceptions when they used the handbook developed for this study. The handbook comprises 203 life science concepts surveyed among preservice teachers holding from advanced researches and arranged by 2007 Revised Science Curriculum. 107 preservice elementary school teachers participated in the study. Forty-six (46) of them were assigned to the experimental group and the other 61 to the control group. ANOVA was conducted for analyzing data. Science Teaching Efficacy Belief Instrument (STEBI) and the life science misconception test which was developed for this study, were administrated as assessing instruments for pretest and posttest. The experimental group, using the handbook, acquired higher scores in both tests on statistical significance level than the control group who were not using the handbook. The results indicate the handbook developed for correcting life science misconceptions for this study is effective in enhancing science teaching efficacy and correcting life science misconceptions.