• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1854-1862
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• 2024

This study aims to investigate the strain-dependent-deformation property of Gyeongju bentonite buffer material. A series of unconfined compressive tests were performed with cylindrical specimens prepared at varying dry densities (𝜌_d = 1.58 g/cm³ to 1.74 g/cm³) using cold isostatic pressing technique. It is found that as 𝜌_d increase, the unconfined compressive strength (q_u), failure strain, and elastic modulus (E) of Gyeongju compacted bentonite (GCB) increases. Normalized elastic modulus (E_sec/E_max) degradation curves of GCB specimens are fitted using Ramberg-Osgood model and the elastic threshold strain (𝜀_e,th) is determined through the fitted curves. The strain-dependency of E and Poisson's ratio (v) of GCB were observed. E and v were measured constant below 𝜀_e,th of 0.14 %. Then, E decreases while v increases after exceeding the strain threshold. The E_sec/E_max degradation curves of GCB in this study suggests wider linear range and higher linearity than those of sedimentary clay in previous study. On top of that, the influence of 𝜌_d is observed on E_sec/E_max degradation curves of GCB, showing a slight increase in 𝜀_e,th with increase in 𝜌_d. Furthermore, an empirical model of q_u with 𝜌_d and a correlation model between q_u and E are proposed for Gyeongju bentonite buffer materials.

• Asia-Pacific Journal of Business
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• v.15 no.3
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• pp.399-415
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• 2024

Purpose - This study aims to explore trading behaviors of individual investors in the KOSDAQ market, thereby explaining the low profitability of individual investors relative to institutional or foreign investors and comparing features specific to the KOSDAQ market with those of the KOSPI market. Design/methodology/approach - KOSDAQ market data, ranging from 2018-01-03 to 2023-12-28, is obtained from the KRX market data system on a daily basis. 12 sub-periods are generated by dividing the entire dataset into 6-month intervals, and within each sub-period, 25 stock-groups are established by the amount of individual investors' net purchases at 4% intervals. The analysis is conducted by comparing major information on trading behaviors across the sub-periods and across the stock-groups. Findings - First, the ratio of individual investors' net purchases shows a negative correlation with the ratio of net purchases of institutional and foreign investors with a strong statistical significance for all sub-periods, and it exhibits negative correlations with the periodic cumulative returns for the most sub-periods. It is also revealed that the low profitability of individual investors might result from the failure of choosing stocks, unlike the case of the KOSPI market where individual investors' low performance is related to the choice of the timing of transactions, rather than the choice of stocks. Research implications or Originality - The empirical results indicate that individual investors in the KOSDAQ market need to be more prudent in choosing stocks than in the KOSPI market, and imply that rediscovering the benefit of the diversification, especially for the KOSDAQ market, might be substantially meaningful.

• Economic and Environmental Geology
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• v.48 no.2
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• pp.115-130
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• 2015

Extended elastic impedance (EEI) is an extension of elastic impedance (EI) which is a generalization of acoustic impedance (AI) for nonzero angles of incidence and can be tuned to be proportional to reservoir properties. In this study, we evaluated EEI inversion by estimating the P-($V_p$) and S-wave velocities ($V_s$), P-wave to S-wave velocity ratio ($V_p/V_s$), and Poisson's ratio of the Second Wall Creek Sand of the Teapot Dome field, Wyoming, USA. We also applied the EEI inversion technique to estimate porosity, gamma-ray values, and density of the Second Wall Creek Sand. Data used in the study include 3-D pre-stack seismic data from the southern part of the field and four wells, selected from a large well database. The $V_s$ logs at the wells were constructed from the $V_p$ logs using the empirical relationships. The percent prediction errors for the four velocity properties are less than about 5% except for Poisson's ratio at one well, supporting that the EEI inversion can be used in the prediction of rock properties. However, the results from the EEI inversion analysis of porosity, gamma-ray values, and density at the wells were unsatisfactory and thus these properties, which are not directly computed from velocities, may not be suitable for EEI inversion.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.347-354
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• 2013

This study was carried out to examine different mole ratio of $H_2/CO_2$ and EBCT using the continuous system in the lab scale throughout biological methods with accumulated hydrogenotrophic methanogen that can convert $CO_2$ to $CH_4$. The experimental-based results with various gas mixtures of mole ratio of 4:1($H_2/CO_2$) and 5:1($H_2/CO_2$), $H_2$ was converted more than 99% conversion rate. In case of $CO_2$, 4:1($H_2/CO_2$) and 5:1($H_2/CO_2$) were $74.45{\pm}0.33%$, $95.8{\pm}10.7%$, respectively, in addition, the study was confirmed that the amount of $H_2$ was more needed than stoichiometric equations, where approach methods are empirical versus theoretical frameworks, for converting total $CO_2$. As such, we have noticed that $H_2$ was used for energy source of hydrogenotrophic methanogen for maintaining life. Regarding the results of the ratio of treatment by retention time, limitation of treatment capacity showed that $H_2$(99.9%) and $CO_2$(96.23%) at EBCT 3.3 hrs indicated stable conversion ratio, as well as appeared that methane production rate and $CO_2$ fixation rate were investigated $1.15{\pm}0.02m^3{\cdot}m^{-3}{\cdot}day^{-1}$ and $2.01{\pm}0.04kg{\cdot}m^{-3}{\cdot}day^{-1}$, respectively.

• Journal of Mushroom
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• v.14 no.3
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• pp.119-126
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• 2016

Five empirical farmhouses were selected to reduce the high temperature damage in oak mushroom cultivation using bed-logs. The cultivation facilities were categorized as follows: those having two blackout curtains or one blackout curtain and outdoor oak mushroom cultivation. The inequality of the indoor condition, oak mushroom hyphae rampant ratio, and fruit body production in each test condition was evaluated. $3^{\circ}C$ was lower in indoor temperature of cultivation facility having two blackout curtains than one blackout curtain. Specifically, the indoor air humidity average of cultivation facilities having one or two blackout curtains was 10% lower than that of outdoor oak mushroom cultivation. This condition is not ideal for oak mushroom cultivation as continuous indoor humidity control is essential for producing good fruit bodies. The Inoculated bed-log surface and oak mushroom hyphae rampant ratio of bed-logs cultivated with two blackout curtains was superior to other tested conditions. The mushroom production ratio observed in facilities with two blackout curtains was 117-204% higher than those cultivated in facilities with only one blackout curtain. Furthermore, the mushroom production ratio increased in based on these findings, we recommended five cultivation facility models to reduce high temperature damage in oak mushroom cultivation using bed-logs.

• Journal of Venture Innovation
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• v.2 no.2
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• pp.117-126
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• 2019

This study conducted correlation analysis and multiple regression analysis using financial statements, loan structure, ROA and ROA volatility of domestic commercial banks, regional banks and special banks for the past five years (2012 ~ 2016). The result is as follows. First, as a result of correlation analysis, bank's ROA is positively related to household loans and SME loans, but it is negatively correlated with the ratio of loans to large companies, sector bias, and loan loss provision ratio. Second, ROA volatility was negatively related to household loans and SME loans, but it was positively correlated with large corporate loans, sector bias ratio, and loan loss provision ratio. Third, as a result of the regression analysis, the variables that have a statistically significant effect on the ROA volatility of banks were household loans, SME loans, and large enterprise loans. From these empirical results, special banks with high volatility in profits need to diversify loan types and sectors in order to achieve business performance outside of policy finance. and Especially, Suhyup Bank and Nonghyup Bank, which have a large commercial role, have a large size per unit by focusing on short-term profit and Rather than focusing on large companies or large loans that are easy to obtain financial information, it is necessary to focus management capabilities on household loans and SME loans by developing capabilities such as screening techniques.

• Resources Recycling
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• v.24 no.1
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• pp.35-42
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• 2015

To obtain the fundamental information on the dissolution of nickel into the slag in the pyrometallurgical processes for treatment of wasted PCB, the distribution ratios of nickel between CaO-$SiO_2-Al_2O_3$-MgO slag and copper-5 wt%Ni alloy were measured at 1623 K to 1823 K under a controlled $CO_2$-CO atmosphere. The distribution ratio of Ni increased linearly with increasing oxygen partial pressure. Therefore, the dissolution reaction of nickel into the slags could be described by the following equation; $$Ni(l)_{metal}+\frac{1}{2}O_2(g)NiO(l)_{slag}$$ The distribution ratio of Ni increased linearly with increasing content of basic oxides(CaO and MgO) in slag. However, the distribution ratio of Ni decreased linearly with increasing temperature. From these results, the empirical equation of distribution ratio of Ni was obtained by the following equation from the analysis of experimental conditions by multiple regression. $${\log}L_{Ni}=0.4000{\log}P_{O2}-5.1{\times}10^{-4}T+0.3375\(\frac{X_{CaO}+X_{MgO}}{X_{SiO2}}\)$$

• Journal of Technology Innovation
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• v.25 no.4
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• pp.239-261
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• 2017

This paper analyzes how corporate product innovation affects firms' revenue and financial stability, and thereby draws the implications for the corporate strategy for sustainable growth. Corporate product innovation is defined as the development of new products within the firm, including bought-in products. Corporate revenue is measured by per capita sales and its growth rate, while financial stability is measured by debt-to-equity ratio and liquidity ratio. In the empirical analysis, the two-stage estimation method was used to control for the endogeneity of new product development. The data are drawn from the first (2005) to the sixth (2015) wave of the Human Capital Corporate Panel (HCCP) Survey, which are matched to the data from the Korea Investors Service (KIS). The results of the first-stage estimation indicate that product innovation of the firm is promoted by the firm's knowledge capital stock, human resources investment, and market-leading strategy. The second-stage estimation results indicate a positive relationship between the firm's level of activity in product innovation and short-term revenue (per capita sales and its growth), and financial stability (lower debt-to-equity ratio and higher liquidity ratio). These findings confirm that the firm's investment in technology innovation and subsequent product innovation are important strategies to enhance both short-term corporate revenue and long-term financial stability.

• Korea journal of population studies
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• v.18 no.2
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• pp.115-168
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• 1995

It is a common wisdom that the long-term economic development of Korea chiefly depends not only on the steady increase of the capital formation but also on the stable increase of the national saving. And also it is a widely accepted opinion that household saving plays a significant role for the smooth supply of investment funds. For the empirical analysis on the determining factors of household saving, consumption function of the household of Korea was utilized indirectly. The reason is that consumption function is regarded as a stable function whereas saving function is considered to be an unstable function of the relevant independent variables. In order to carry out the regression process of the consumption functions, data on the family income and expenditure survey and the farm household economy survey was used. The regression result could be summarized as follows : Firstly, household income and the number of the employed in the household have the negative effect in determining the consumption ratio of the Korean households. On the other hand, ages and the educational attainment of the household heads as well as the number of the household members have the positive effect. During the early part of 21st century, the consumption ratio of the Korean households is expected to be decreased because of the increasing trend of household income, and the ever increasing number of the employed member of the household based on the increasing trend of the labor force participation rate of women and the decrease of the average size of the number of household members owing to widespread nuclear family system. On the other hand, the consumption ratio of the household of Korea is expected to be increased because of the continuous increase of the average ages of the household heads caused by the population aging phenomena and improvement of the educational attainment of the household heads. But on the whole, household saving ratio is expected to be increased owing to the secular downward trend of the consumption and therefore no significant difficulties are anticipated for the smooth provision of investment resources needed to have long-term economic progress of Korea.

• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.60-68
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• 1991

In compacting the melt-spun $Nd_{14}Fe_{76}Co_{4}B_{6}$ and $Nd_{10.5}Fe_{79}Co_{2}Zr_{15}B_{7}$ magnetic powders. the difference in composition induces a different behavior of closed packing rate as a function of aspect ratio of the powders. The $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy having a low Co/Fe ratio (low density) shows the better green density to have an enhanced closed packing rate. An empirical power equation relating the green density with the compacting pressure was obtained such as ${\phi}(g/cm^{2})=5.2~5.6{\times}P^{0.045~0.065}(ton/cm^{2})$. The $Nd_{14}Fe_{76}Co_{4}B_{6}$ alloy having a high Nd/Fe ratio possesses much finer grain size(50~60 nm) than that of $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ alloy and shows the higher coercivity($iH_{c}=14~15kOe$). The higher Nd/Fe ratio in the melt-spun Nd-Fe-Co-B alloy, where the domain wall pinning mechanism was found to be predominant, assists the formation of Nd-rich grain boundary phase acting as a pinning site. The grain boundary ranges over $12~16\;{\AA}$ thick in the Nd-Fe-Co-B alloy while it ranges over $8~12\;{\AA}$ thick in the Nd-Fe-Co-Zr-B alloy.