• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.737-749
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• 2007

Flexural design of double composite box girder over the interior pier for three-span continuous bridge was performed by the LRFD method. The maximum span length of the continuous bridge ranged from 80m to 120m and the relative ratio of the span length was assumed to be 1:1.25:1. The girder section was designed for the strength limit state and service limit state with additional design check for constructibility. Before the bottom concrete and compression flange showed a complete composite action, the buckling of lower compression flange was checked. The flexural stiffness and flexural resistance characteristics for the section and for the constituent members such as tension flange, compression flange, and web were analyzed for different thicknesses of the bottom concrete on top of the compression flange. The effect of the distribution ratio of steel between the top and bottom flanges was investigated by analyzing ductility behavior and stress distribution through the girder's depth for several different relative area ratios of steel between the top and bottom flanges. It was found that a total amount of 15% of steel can be saved by applying the double composite system compared with that of the conventional composite system.

• Journal of the Mineralogical Society of Korea
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• v.28 no.2
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• pp.95-108
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• 2015

Nano-sized iron colloids are formed as acid mine drainage is exposed to surface environments and is introduced into surrounding water bodies. These iron nanomaterials invoke aesthetic contamination as well as adverse effects on aqueous ecosystems. In order to control them, the characteristics of their behaviour should be understood first, but the cumulative research outputs up to now are much less than the expected. Using zero-valent iron (ZVI) and magnetite, this study aims to investigate the behaviour of iron nanomaterials according to the change in the composition and pH of background electrolyte and the concentration of natural organic matter (NOM). The size and surface zeta potential of iron nanomaterials were measured using dynamic light scattering. Characteristic behaviour, such as aggregation and dispersion was compared each other based on the DLVO (Derjaguin, Landau, Verwey, and Overbeek) theory. Whereas iron nanomaterials showed a strong tendency of aggregation at the pH near point of zero charge (PZC) due to electrostatic attraction between particles, their dispersions became dominant at the pH which was higher or lower than PZC. In addition, the behaviour of iron nanomaterials was likely to be more significantly influenced by cations than anions in the electrolyte solutions. Particularly, it was observed that divalent cation influenced more effectively than monovalent cation in electrostatic attraction and repulsion between particles. It was also confirmed that the NOM enhanced the dispersion nanomaterials with increasing the negative charge of nanomaterials by coating on their surface. Under identical conditions, ZVI aggregated more easily than magnetite, and which would be attributed to the lower stability and larger reactivity of ZVI.

• Korean Journal of Microbiology
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• v.32 no.3
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• pp.222-231
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• 1994

Kinetic analysis was done to elucidate the reaction mechanism of purine nucleoside phosphorylase (PNP) in Saccharomyces cerevisiae. The binary complexes of PNP${\cdot}$phosphate and PNP${\cdot}$ribose 1-phosphate were involved in the reaction mechanism. The initial velocity and product inhibition studies demonstrated were consistent with the predominant mechanism of the reaction being an ordered bi, bi reaction. The phosphate bound to the enzyme first, followed by nucleoside and base were the first product to leave, followed by ribose 1-phosphate. The kinetically suggested mechanism of PNP in S. cerevisiae was in agreement with the results of protection studies against the inactivation of the enzyme by sulfhydryl reagents, p-chloromercuribenzoate (PCMB) and 5,5'-dithiobisnitrobenzoate (DTNB). PNP was protected by ribose 1-phosphate and phosphate, but not by nucleoside or base, supporting the reaction order of ordered bi, bi mechanism. PCMB or DTNB-inactivated PNP was totally reactivated by dithiothreitol (DTT) and the activity was returned to the level of 77% by 2-mercaptoethanol, indicating that inactivation was reversible. The kinetic behavior of the PCMB-inactivated enzyme had been changed with higher $K_m$ value of inosine and lower $V_m$, and was restored by DTT. Inactivation of enzyme by DTNB showed similar pattern of K sub(m) value with that by PCMB, but had not changed the $V_m$ value, significantly. Negative cooperativity was not found with PCMB or DTNB treated PNP at high concentration of phosphate.

• The Korean Journal of Financial Management
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• v.27 no.2
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• pp.1-33
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• 2010

This study explores if the higher initial returns and the poorer long-run performance observed in the IPOs markets are associated with the firms offered in the 'hot markets,' and then empirically examines the effect of optimistic investors' sentiment on this phenomenon, particularly in the aspects of both pricing mechanism and the opportunistic behavior of offering firms. We analyzed a total of 432 IPO firms for the years between 2001 and 2005. This analysis finds that the initial returns and long-run under-performances of 'IPOs in the hot market' are significantly higher than those of 'IPOs in the cold market.' This study also finds that the proxy variables for the optimistic investors' sentiment have a positive effect on the initial return and negative effect on the long-run performance. Finally, this research finds no difference of ownership structure, venture capital backed, and financial properties between hot market IPOs and cold market IPOs. R&D expenditure rate and financial qualities of IPOs are higher in the hot market than in the cold market. These results do not support the 'windows of opportunity' hypothesis that low quality firms take advantage of hot market condition for successful IPOs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2015-2022
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• 2008

The effect of content of $Al_2O_3+Y_2O_3$ sintering additives on the densification behavior, mechanical and electrical properties of the pressureless-sintered $SiC-ZrB_2$ electroconductive ceramic composites was investigated. The $SiC-ZrB_2$ electroconductive ceramic composites were pressurless-sintered for 2 hours at 1,700[$^{\circ}C$] temperatures with an addition of $Al_2O_3+Y_2O_3$(6 : 4 mixture of $Al_2O_3$ and $Y_2O_3$) as a sintering aid in the range of $8\;{\sim}\;20$[wt%]. Phase analysis of $SiC-ZrB_2$ composites by XRD revealed mostly of $\alpha$-SiC(6H), $ZrB_2$ and In Situ YAG($Al_5Y_3O_{12}$). The relative density, flexural strength, Young's modulus and vicker's hardness showed the highest value of 89.02[%], 81.58[MPa], 31.44[GPa] and 1.34[GPa] for $SiC-ZrB_2$ composites added with 16[wt%] $Al_2O_3+Y_2O_3$ additives at room temperature respectively. Abnormal grain growth takes place during phase transformation from $\beta$-SiC into $\alpha$-SiC was correlated with In Situ YAG phase by reaction between $Al_2O_3$ and $Y_2O_3$ additive during sintering. The electrical resistivity showed the lowest value of $3.l4{\times}10^{-2}{\Omega}{\cdot}cm$ for $SiC-ZrB_2$ composite added with 16[wt%] $Al_2O_3+Y_2O_3$ additives at 700[$^{\circ}C$]. The electrical resistivity of the $SiC-TiB_2$ and $SiC-ZrB_2$ composite was all negative temperature coefficient resistance (NTCR) in the temperature ranges from room temperature to 700[$^{\circ}C$]. Compositional design and optimization of processing parameters are key factors for controlling and improving the properties of SiC-based electroconductive ceramic composites.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.209-218
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• 2020

This study examined the sexual function, sexual distress, and quality of life of middle-aged women with osteoarthritis, as well as the factors influencing the quality of life. The participants were 121 middle-aged women who have been suffering osteoarthritis. Data collection was conducted from September 1 to October 31, 2019. The instruments were the Female Sexual Distress Scale (FSDS), the Female Sexual Function Index (FSFI), and the World Health Organization Quality of Life Assessment Instrument (WHOQLO) -BREF scale. Data were collected with structured questionnaires and analyzed using a t-test, ANOVA, Pearson's correlation analysis, and multiple regression analysis. A positive correlation was observed between sexual function and quality of life, whereas sexual distress had a negative correlation between sexual function and the quality of life. Factors affecting the quality of life of middle-aged women with osteoarthritis were sexual function, sexual distress, which explained 16.1%. Sexual distress, sexual function, and quality of life showed a correlation. Therefore, it is important to develop a nursing intervention that can improve the sexual function and reduce the sexual distress of middle-aged women with osteoarthritis to improve their quality of life.

• Resources Recycling
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• v.15 no.3 s.71
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• pp.58-65
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• 2006

The applicability of the waste pulp which produced in the paper recycling process as an adsorbent for the treatment of $Ni^{2+}$ ion in wastewater has been investigated taking the initial concentration of adsorbate, temperature, the amount of adsorbent, and solution pH as the experimental variables. In addition, the effect of the concentration of coexisting solute and pre-treatment of adsorbent on the adsorbability of $Ni^{2+}$ ion were also examined. The electrokinetic potential of waste pulp was observed to be positive below pH 7.8 and negative above this pH. The adsorption reaction of $Ni^{2+}$ ion reached its equilibrium within 4 hours after the reaction was initiated and the adsorbed amount of adsorbate was found to increase with its initial concentration. The adsorbability of $Ni^{2+}$ was raised with temperature so that its adsorption reaction was considered to be exothermic, which was substantiated by thermodynamic calculation. Also, the adsorbed amount of $Ni^{2+}$ was raised with the amount of waste pulp and with pH in the range of pH $3{\sim}6$. This behavior of the adsorption of $Ni^{2+}$ according to the solution pH was well agreed with the electrokinetic characteristics of waste pulp in solution. The amount of coexisting solute was observed to reversely affect on the $Ni^{2+}$ adsorption onto waste pulp under the experimental conditions. With regard to the pre-treatment of adsorbent with NaOH, the adsorbability of $Ni^{2+}$ was increased with the concentration of NaOH to a certain extent. However, it was found to decrease contrarily when the concentration of NaOH became too high.

• Journal of Music and Human Behavior
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• v.4 no.2
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• pp.41-65
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• 2007

This study examines children's responses on Audie music activity based on Gordon's Music Learning Method. Subjects of study were 3 five year old children(2 boys, 1 girl) in kindergarten. Data collection drew from participatory observation, researcher journal, the classroom teacher interview. Where more specific data were necessary, video and digital camera recorded. The data were described, analyzed, and interpreted. The main findings in this study are as follows : The children who participated in Audie music activity showed desirable changes in many ways. Their music listening attitude was the one that changed most remarkably. At the beginning activity application, the children were not naturally and could not listen attentively while researcher was singing song without words. Gradually children could listen attentively to the researcher's singing without words. Through the Audie music activity, the children began to think carefully the tone and rhythm of music and to express themselves freely and creatively. At the beginning activity application, the children who showed negative responses and blocked up activity became gradually able to show positive aptitude and to amuse. Also the children who showed passive attitude and no responses became gradually able to react spontaneously.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.4
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• pp.57-68
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• 2020

This study analyzed the factors affecting the reemployment intention of the baby boomer. To this end, an extended Model of Goal-directed Behaviors(MGB) was set as a research model. The extended MGB used in this study added economic readiness and social capital to attitudes, subjective norms, positive anticipated emotions, and perceived behavioral control variables as independent variables. The desires was set as a mediating and the reemployment intention was set as the dependent variable. The research model was empirically analyzed with 201 baby boomers. Empirical analysis showed that economic preparation had a negative effect on reemployment intention, and social capital had a positive effect on reemployment intention. Economic preparation rather than social capital was found to have a stronger impact on the intention of reemployment. Attitudes, subjective norms, positive anticipated emotions, and perceived behavioral control variables were not tested for a significant direct effect on reemployment intention. They were found to have a significant influence on reemployment intention through the mediating of desires. Based on the results of this empirical analysis, academic and practical implications were presented.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.288-295
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• 1999

Nineteen japonica and Tongil-type rices were selected from seventy nine Korean and Japanese rice cultivars grown in 1989 based on the water uptake behavior of milled rice under the room temperature and boiling conditions. The selected rice cultivars were investigated for water absorbability and some physicochemical characteristics of milled rice, proper water amount for cooking and sensory evaluation of cooked rice. The relationships among the tested grain properties were also examined. The highest varietal variation of water uptake rate was observed at twenty minutes after soaking in water. The maximum water uptake of milled rices at room temperature occurred mostly at about eighty minutes after soaking in water. Newly harvested rices showed a significantly lower water uptake rate of milled rice at 20 minutes after soaking, a relatively higher maximum water absorption ratio under the room temperature, and the less water uptake and volume expansion of boiled rice compared with the one-year old rice samples. The water uptake rate and the maximum water absorption ratio showed significantly negative correlations with the K/Mg ratio and alkali digestion value(ADV) of milled rice. The rice materials showing the higher amount of hot water absorption exhibited the larger volume expansion of cooked rice. The harder rices with lower moisture content revealed the higher rate of water uptake at twenty minutes after soaking and the higher ratio of maximum water uptake under the room temperature condition. These water uptake characteristics were not associated with the protein and amylose contents of milled rice ansd the palatability of cooked rice. The water/rice ratio(in w/w basis) for optimum cooking was averaged to 1.52 in dry milled rices (12% wet basis) with varietal range from 1.45 to 1.61 and the expansion ratio of milled rice after proper boiling was averaged to 2.63(in v/v basis). The water amount needed for optimum cooking was the lowest in Cheongcheongbyeo (Tongil-type rice) and the highest in Jinbubyeo, and the amount could be estimated with about 70% fittness by the multiple regression formula based on some water uptake characteristics, ADV and amylose content of milled rice as the independent variables. Nineteen rice cultivars were classified into seven groups based on scatter diagram projected by principal component analysis using eight properties related to water uptake and gelatinization of milled rice.