• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.985-993
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• 1997

The effects of CaO and MgO fluxes on the fusibility of fly-ashes were investigated for two different fly-ashes. A fusion temperature of mixtures of selected fly-ashes and fluxes were measured by the ASTM test method(D1857) and the differential thermal analysis. IDT of these samples added CaO and MgO as a fluxing agent dropped in the range of 114 to $294^{\circ}C$ and 80 to $224^{\circ}C$, respectively. Compared with ash fusion temperature to Base/Acid ratio, the lowest ash fusion temperature were measured in the range of 0.7 to 0.8 for CaO-fly ash mixtures and 0.3 to 0.4 for MgO-fly ash mixtures. As a result, MgO in small addition acted as a more effective flux than CaO. A conventional Base/Acid ratio and liquidus point of ternary diagram did not show a good correlation with ash fusion temperature for these samples. In pure fusion temperature of fly ash-mixtures, DTA was better method than ASTM test method.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.554-558
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• 2008

$(1-x)SiO_2-(x)TiO_2$ composite fibers with various compositions of $TiO_2$ were prepared by electrospinning their sol-gel precursors of titanium (IV) iso-propoxide (TiP), and tetraethyl orthosilicate (TEOS). The surface morphology and structure of sintered composite fibers were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), simultaneous thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) and Fourier transform infrared spectroscopy (FT-IR). As the content of $TiO_2$ in $(1-x)SiO_2-(x)TiO_2$ system was increased the average diameter of composite fibers was proportionally increased. Also, the transformation of $TiO_2$ from anatase to rutile form was inhibited by the highly dispersed $TiO_2$ around $SiO_2$ particles up to $0.6SiO_2-0.4TiO_2$ composite fibers even after calcination at $1000^{\circ}C$. The photocatalytic activity of $SiO_2-TiO_2$ composite fibers was examined for the methylene blue (MB) decomposition which was confirmed using UV-vis/DRS spectra. The experiments demonstrated that the MB in aqueous solution was successfully photodegraded using $SiO_2-TiO_2$ composite nanofibers under UV-visible light irradiation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.193-203
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• 2011

The purpose of this study, looking to which the recycled fine aggregates from waste concrete have a lot of problems as a material for structure purpose, is applying the recycled fine aggregate to Self-Compacting Concrete(In the reminder of this paper, it often referred to as SCC) by using the characteristic which the powder containing the recycled fine aggregates can increase strength and liquidity. In this study, that is, the recycled fine aggregate powder is appropriate for developing high strength(over 40 MPa) and liquidity(JSCE 2 grade), the characteristic of the SCC and it was increased the ratio of mixing the recycled fine aggregates emerging from waste concrete and the normal fine aggregates by 25%, making differential in total 5 levels and applied to SCC. After all, this study was reviewed the physical properties of the fresh concrete, analyzed the mechanical properties and durability of the hardening concrete and tried to ensure the possibility of utilizing the recycled fine aggregates as a material for SCC. As a result, this study reached a conclusion that among the 5-level replacement ratios of the physical, mechanical analysis and the durability characteristics, the normal fine aggregates could be applied up to a replacement ratio of 50% more than the recycled fine aggregates and resulted in a deterioration in performance the replacement ratio larger than 50%. It is judged that the applicability of the real structures should be followed up in order to check the possibility of applying the recycled fine aggregates to real life.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.343-351
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• 2016

Cryogenic spray characteristics of a nitrogen swirl injector operating in supercritical environment have been numerically investigated. By comparing the equation of states(EOS) used for supercritical condition, SRK EOS was applied to predict the nitrogen thermodynamic property under supercritical environment. A Chung's method was implemented for the calculation of viscosity and conductivity and Takahashi's correlation based on Fuller's Theorem was implemented for the calculation of diffusion coefficient. By injecting the nitrogen with 5 bar differential pressure into 50 bar chamber filled with nitrogen, numerical simulation has been conducted. The dynamic Smagorinsky sub-grid scale (SGS) model has been compared with the algebraic Smagorinsky SGS model using FFT frequency analysis. The instability at the liquid film and gas core inside injector and the propagation of pressure oscillation into the injector has been investigated. The spreading angle of swirl injector obtained by numerical calculation has been validated with experimental result.

• Food Science of Animal Resources
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• v.36 no.1
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• pp.29-36
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• 2016

This study was performed to investigate the role of pH and temperature postmortem, and to demonstrate the importance of these factors in determining meat quality. Postmortem pH_45min (pH at 45 min postmortem or initial pH) via analysis of Pearson’s correlation showed high positive correlation with pH change pH_c24 (pH change from pH_45min to pH_24h postmortem). However, postmortem pH after 24 h (pH_24h or ultimate pH) had a high negative correlation with pH change, pH_c24, CIE L*, and protein content. Initial temperature postmortem (T_1h ) was positively associated with a change in temperature from 45 min to 24 h postmortem (T_c24) and cooking loss, but negatively correlated with water holding capacity. Temperature at 24 h postmortem (T_24h) was negatively associated with T_c24. Collectively, these results indicate that higher initial pH was associated with higher pH_c24, T_1h, and T_c24. However, higher initial pH was associated with a reduction in carcass weight, backfat thickness, CIE a* and b*, water holding capacity, collagen and fat content, drip loss, and cooking loss as well as decreased shear force. In contrast, CIE a* and b*, drip loss, cooking loss, and shear force in higher ultimate pH was showed by a similar pattern to higher initial pH, whereas pH_c24, carcass weight, backfat thickness, water holding capacity, fat content, moisture content, protein content, T_1h, T_24h, and T_c24 were exhibited by completely differential patterns (p<0.05). Therefore, we suggest that initial pH, ultimate pH, and temperatures postmortem are important factors in determining the meat quality of pork.

• Journal of Gifted/Talented Education
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• v.22 no.3
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• pp.757-777
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• 2012

Peer relationships in young students' communities are one of the important factors influencing the cognitive and affective domains of learning. Moreover, students who join the special program for gifted students possess differential peer relationships from the students in general classes. This study aims to explore the differences of 5th grade five science-gifted students' peer relationships between students in special classes for gifted students and general classes. Five students in the special program for gifted students, managed by the Office of Education in a southern city, participated in this study. Social network analyses were utilized to explore participants' peer relationships; the students' homeroom teacher was interviewed to explore the contextual and in-depth characteristics of gifted students' peer relationships. The results illustrated four cases of peer relationships: (1) smart loner (2) my study mate (3) I'm the best in my class, and (4) a good friend anywhere. This study identified that the gifted students possessed diverse peer relationships in both the special program and general classroom. In addition, this study suggests that the program for gifted students needs to be specially designed based on the gifted students' peer relationship.

• Journal of the Korean Geotechnical Society
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• v.28 no.8
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• pp.5-19
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• 2012

Vertical drains along with the preloading technique have been commonly used to enhance the consolidation rate of dredged placement formation. In practice, vertical drains are usually installed in the process of self-weight consolidation of a dredged soil deposit because this process takes considerable time to be completed, which makes conventional analytical or numerical models difficult to quantify the consolidation behavior. In this paper, we propose a governing partial differential equation and develop a numerical model for 2-D axisymmetric non-linear finite strain consolidation considering self-weight consolidation to predict the behavior of a vertical drain in the dredged placement foundation which is installed during the self-weight consolidation. In order to verify the developed model in this paper, results of the numerical analysis are compared with that of the lab-scaled self-weight consolidation test. In addition, the model verification has been carried out by comparing with the simplified method. The comparisons show that the developed model can properly simulate the consolidation of the dredged placement formation with the vertical drains installed during the self-weight consolidation. Finally, the effect of construction schedule of vertical drains and of pre-loading during the self-weight consolidation is examined by simulating an imaginary dredged material placement site with a thickness of 10 m and 20 m, respectively. This simulation infers the applicability of the proposed method in this research for designing a soil improvement in a soft dredged deposit when vertical drains and pre-loading are implemented before the self-weight consolidation ceases.

• Journal of the Korean Home Economics Association
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• v.30 no.2
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• pp.1-20
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• 1992

The purpose of this study was to investigate(Ⅰ) the effect of a masculine-feminine image in women's suit on the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations, and (2) the effect of perceiver's sex, sex-role attitudes, and occupation on the perception formed by the function of clothing cues. The research design of the study consisted of 2(pink and navy blue colors) × 4(masculine and feminine forms) factorial design of a suit. The experimental materials developed for this study were a set of stiuli and 2 response scales. The stimuli consisted of 8 drawings of woman's clothing made by systematic manipulations of 2 independent variables(color and form) in drawings of suit. The dependent variables were the perceptions of the wearer's occupational characteristics and suitability of the masculine or feminine clothing for certain occupations. Occupational characteristics were measured with a 7-point semantic differential scale composed of 21 bipolar adjectives. Perception of ccupational suitability was assessed with 12 items of 5-point Likert type questions. In addition, the Bem Sex-role Inventory was used to assess perceiver's sex-role attitudes. The subjects consisted of 393 men and 389 women, whose occupations were classified as professionals, secondary school teachers, and white-collar workers. They were randomly assigned to one of 8 suit. The data were analyzed by factor analysis, MANOVA, ANOVA, Mean and S.D. Three factors emerged to account for the perception of occupational characteristics. These factors were given the titles of (1) activity, (2) potency, and (3) evaluation factors. The activity factor was the largest, including 9 adjectives. Differences in the form of the suit had effects on potency and evaluation for both sexes, while it also had some effect on activity for women. The color of the suit had some effect on evaluation for both sexes. Strong effects of color and form on the suit were seen in perception of occupational suitability for the occupations of attorney(masculine) and secretary(feminine). On suitability for secondary school teaching occupation, the effects of color and form of suit differed by sex of the subjects. Perceiver's sex-role attitudes and occupation paritally influenced the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations. In summary, a masculine-feminine image of clothing had a significant effect on the perception of occupational characteristics as well as on suitability of the clothing for certain occupations. Thus, the results of the study support the implicit personality theory on person perception and also the stereotypes of sex-roles on the perception of occupational suitability.

• Journal of the Korean Home Economics Association
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• v.30 no.2
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• pp.21-34
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• 1992

The purpose of this study was to investigate (1) the effect of a masculine-feminine image in women's blouse·skirt on the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations, and (2) the effect of perceiver's sex, sex-role attitudes, and occupation on the perception formed by the function of clothing cues. The research design of the study consisted of 2(skirt color) × 2(blose color) × 3(masculine-feminine blouse forms) factorial desing of a blouse·skirt set. The experimental materials developed for this study were a set of stimuli and 2 response scales. The stimuli consisted of 12 drawings of woman's clothing made by systematic manipulations of 2 independent variabels (color and form) in drawings of blouse-skirt. The dependent variables were the perceptions of the wearer's occupational characteristics and suitability of the masculine or feminine clothing for certain occupations. Occupational characteristics were measured with a 7-point semantic differential scale composed of 21 bipolar adjectives. Perception of occupational suitability was assessed with 12 items of 5-point Likert type questions. In addition, the Bem Sex-role Inventory was used to assess perceiver's sex-role attitudes. The subjects consisted of 393 men and 389 women, whose occupations were classified as professionals, secondary school teachers, and white-collar workers. The data were analyzed by factor analysis, MANOVA, ANOVA, Mean and S.D. Three factors emerged to account for the perception of occupational characteristics. These factors were given the titles of (1) activity, (2) potency, and (3) evaluation factors. The activity factor was the largest, including 9 adjectives and accounting for 33.3% of the variance in blouse-skirt. On the blouse-skirt set, the form of the blouse had an effect on activity and evaluation for both sexes, while the color of the skirt had an effect on evaluation for both sexes as well as on potency for men. Strong effect of color and form on blouse·skirt were seen in perception of occupational suitability for the occupations of attorney(masculine) and secretary(feminine). On suitability for secondary school teaching occupations, the effects of color and form of blouse·skirt differed by sex of the subjects. Male subjects determined suitability by the color of the blouse, while female subjects determinied suitability on the basis of the form of the blouse. Perceiver's sex-role attitude and occupation partially influenced the perception of the wearer's occupational characteristics and suitability of the clothing for certain occupations.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.33 no.2
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• pp.124-130
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• 2007

In the present study, I investigated the effects of N-methyl-D-aspartate (NMDA), arachidonic acid (AA), and Nitric Oxide Synthase Inhibitor (NOSI), alone or in combination, on the proliferation of cultured primary normal human oral keratinocytes (NHOK). The purpose of this study was therefore the preliminary study for the examination of the interaction between these agents and NHOK in order to elucidate the mechanisms by which epithelial growth and regeneration are regulated. NHOK were obtained from gingival tissue of 20 individuals aged 20 to 29, and third passage (P3) cells were used for this study. The DNA synthesis was measured by the BrdU assay. Addition of low concentration of AA ($1{\mu}M$) and high concentration of AA with NMDA group (NMDA+AA $10{\mu}M$) made DNA synthesis rate increase significantly at the early stage. Adding NNA ($10{\mu}M$) affected DNA synthesis rate to increase significantly in 4 hours. At the early stage, DNA synthesis was significantly active in the NOS-I with NMDA groups than in the control and the NMDA-only group, while it didn't become statistically meaningful in 24 hours. AA $1{\mu}M$ and NNA $10{\mu}M$ may induce the proliferation of the NHOK independently and NOS-I may induce the proliferation of the NHOK with NMDA. These reactions might be related to the NMDA receptor in the cell and the change of the intracellular calcium ion concentration.