• Journal of Biosystems Engineering
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• v.34 no.1
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• pp.8-14
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• 2009

When a farmer buys a tractor, the power size of a tractor is determined by various factors such as farm size, farmer's age, farming type, topographical area of farm. Relationships between tractor selection and these factors were found. Three regression models were developed to analyze the relationship. Those models were an OLS-1 model (based on 567 samples having tractors), an OLS-2 model, and a Tobit model (both based on the 1,941 samples). Regression analysis results showed that farm size and farmer's age affected selection of power size for all models at an 1% significance level. It was also shown that some farming types also had significant relationships with the tractor power size. Upland cultivating farmers and livestock farmers had larger tractors than rice cultivating farmers, while orchard farmers had smaller tractors. As for the topographical area, only middle area had significant difference with plain area. Farmers who had a rice-transplanter or a combine had larger tractors than those who didn't.

• Journal of Microbiology and Biotechnology
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• v.30 no.4
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• pp.533-539
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• 2020

A quantitative real-time polymerase chain reaction (QPCR) was applied to estimate biokinetic coefficients of Clostridium cadaveris and Clostridium sporogenes, which utilize protein as carbon source. Experimental data on changes in peptone concentration and 16S rRNA gene copy numbers of C. cadaveris and C. sporogenes were fitted to model. The fourth-order Runge-Kutta approximation with non-linear least squares analysis was employed to solve the ordinary differential equations to estimate biokinetic coefficients. The maximum specific growth rate (μ_max), half-saturation concentration (K_s), growth yield (Y), and decay coefficient (K_d) of C. cadaveris and C.sporogenes were 0.73 ± 0.05 and 1.35 ± 0.32 h^-1, 6.07 ± 1.52 and 5.67 ± 1.53 g/l, 2.25 ± 0.75 × 10¹⁰ and 7.92 ± 3.71 × 10⁹ copies/g, 0.002 ± 0.003 and 0.002 ± 0.001 h^-1, respectively. The theoretical specific growth rate of C. sporogenes always exceeded that of C. cadaveris at peptone concentration higher than 3.62 g/l. When the influent peptone concentration was 5.0 g/l, the concentration of C.cadaveris gradually decreased to the steady value of 2.9 × 10¹⁰ copies/ml at 4 h Hydraulic retention time (HRT), which indicates a 67.1% reduction of the initial population, but the wash out occurred at HRTs of 1.9 and 3.2 h. The 16S rRNA gene copy numbers of C. sporogenes gradually decreased to steady values ranging from 1.1 × 10¹⁰ to 2.9 × 10¹⁰ copies/ml. C. sporogenes species was predicted to wash out at an HRT of 1.6 h.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.144-149
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• 2017

This study empirically analyzes the effect of IT SME ventures' external information network diversity on their production period reduction and productivity improvement generated from technology development. This research constructs a mediating model based on the open innovation perspective and tests it with the 138 samples of South Korean IT SME ventures based on the ordinary least squares regression. This research is expected to make a good contribution by shedding a new light on the following three points about the critical role of IT SME ventures' external information network diversity in increasing their production period reduction and productivity improvement generated from technology development which has scarcely been illuminated in the extant studies in the field of the management of technology for SMEs. First, IT SME ventures' external information network diversity positively influences their production period reduction. Second, the external information network diversity positively influences IT SMEs' ventures' productivity improvement. Third, IT SME ventures' production period reduction partially mediates the influence of IT SME ventures' external network diversity on their productivity improvement. These three fresh points are expected to provide useful theoretical and practical implications. Related to the theoretical implication, this research provides a fresh implication that IT SME ventures' external information network diversity positively influences not only their production period reduction but also productivity improvement generated from technology development. Concerning the practical implication, this study suggests that the CEOs in IT SME ventures make strategic efforts to use more diverse external information sources in order to increase their production period reduction and productivity improvement generated from technology development.

• Journal of Digital Convergence
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• v.16 no.3
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• pp.121-127
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• 2018

Enterprises' new technology development capability is essential for creating successful product innovation and process innovation in the heavy competition in the business context changing quickly with technology convergence and development. Based on the open innovation perspective, this research develops a research model about the direct effect of small and medium venture companies' exterior information network heterogeneity on their new technology development capability and the mediating impact of their product planning capability on this direct effect. This study statistically tests the research model by using the ordinary least squares regression with the 683 small and medium venture companies, providing two major findings as follows. One finding is that small and medium venture companies' exterior information network heterogeneity positively impacts their new technology development capability. The other finding is that small and medium venture companies' product planning capability perfectly mediates the positive effect of their exterior information network heterogeneity on their new technology development capability.

• Korean Journal of Construction Engineering and Management
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• v.13 no.2
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• pp.128-136
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• 2012

In this study, we investigated the macroeconomic variables that affect housing prices thus creating a large impact on people's lives as well as the real estate market. For the study, the macroeconomic variables able to influence the House Rental Price (housing price by lease or deposit) were used for an analysis as follows: housing sales price index, household loans rate, total household savings, the number of employees and a multiple regression analysis was performed using a time series for each macroeconomic variable. As a result of the analysis, the House Rental Price was affected by all of four macroeconomic variables. The House Rental Price increased as each variable enlarged. In conclusion, this study may be useful for finding a solution for stabilizing the House Rental Price as well as for the establishment of efficient and sustainable policies for the housing market.

• Journal of Digital Convergence
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• v.13 no.12
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• pp.55-62
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• 2015

IT SMEs' product planning, product design, and manufacturing capabilities are of importance to creating their sustainable competitive advantages in the context of digital convergence. However, there have been few empirical studies investigating the relationships among them, which has made this research attempt to model the relationships and empirically test them. Especially, this study divided IT SMEs' product design capability into the product exterior and interior design capabilities and focused on the mediating effects of the product exterior and interior design capabilities between the product planning and manufacturing capabilities. By analyzing the 310 samples of Korean IT SMEs with the ordinary least squares regression analysis, this study has empirically revealed that IT SMEs' product exterior and interior design capability jointly and fully mediate the positive relationship between their product planning and manufacturing capabilities.

• Journal of Distribution Science
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• v.12 no.3
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• pp.65-73
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• 2014

Purpose - Aging and fewer economically active people have challenged the assumption of continuous population increases. A new real estate valuation methodology reflecting changes in population structure is thus needed. Research design, data, and methodology - The relationship between demographic change and changes in real estate prices is analyzed using ordinary least squares (OLS) to estimate the parameters, and a population structure change (PSC)-Binomial Option Model is developed to assess the volatility of the estimated parameters. Results based on Seoul and Shanghai data are compared. Results - Results of the DCF method indicate that investing in Seoul is better than investing in Shanghai, but the binomial option indicates the opposite. The PSC-binomial option model, reflecting changes in population structure, yields higher values (24.6 million won in Seoul and 43.3 million won in Shanghai) than those given by the binomial option model. Conclusions - This study indicates that applying changes in population structure to existing research, such as in the binomial option model, represents a more accurate real estate valuation method. Results demonstrate that the new model is more accurate than existing models such as the DCF or binomial option.

• Health Policy and Management
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• v.29 no.4
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• pp.496-501
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• 2019

Background: In this study, wage status and wage determinants of care workers were analyzed. Methods: The analysis used database (DB) of long-term care institutions, DB of long-term care institutions, DB of long-term care workers, DB of health insurance qualification, and contribution possessed by National Health Insurance Services. We analyzed the wage status of the care workers from 2009 to 2016 through basic analysis and estimated the factors affecting the wage of the long-term care facilities' care workers using pooled ordinary least squares. Results: The monthly average wage of care workers was raised from Korean won (KRW) 1.37 million in 2009 to KRW 1.52 million in 2016, and the working hours were shortened by 20 hours from 207 hours to 187 hours. Hourly wages increased by KRW 1,329 from KRW 6,831 in 2009 to KRW 8,160 in 2016. The average monthly wage of care workers was affected by gender, age, years of employment, monthly working hours, establishment type, city size, institutional size, the grade of the institution, and management status. In particular, the wage level of the care workers was high when the larger the size of the institution, the better the management status (fill rate), the establishment type is "government and local government" and "corporation," the institutional rating is high, and the facility manager has the first grade of the social worker license. Conclusion: The government should consider aggressive policies to improve the treatment of care workers as well as the quality of long-term care services so that there will be more long-term care facilities that are guaranteed social publicity above a certain level.

• Journal of Korea Port Economic Association
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• v.31 no.3
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• pp.41-60
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• 2015

This paper investigates whether managerial ownership and foreign ownership have impacts on firm value, using a sample of logistics firms listed on the Korea Stock Exchange between 2008 and 2014. In the Korean economy, family-controlled business groups, known as chaebol, constitute a unique governance system. To acquire investments from controlling shareholders, a logistics firm is likely to be included in family-controlled business groups. Since reform of the governance structure of logistics firms in the South Korea enables shareholder value to be maximized, we analyzed ownership effects on firm value using pooled ordinary least squares. Empirical results showed that there was a significant positive relation between managerial ownership and firm value. This study also found that there was a significant positive relation between foreign ownership and firm value. We thus show that both managerial ownership and foreign ownership can protect shareholders by positively affecting firm values.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.461-471
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• 2012

The purpose of this paper is to visualize the housing market dynamics with ESDA (Exploratory Spatial Data Analysis) using MATLAB toolbox, in terms of the modeling housing market dynamics in the Busan Metropolitan City. The data are used the real housing price transaction records in Busan from the first quarter of 2006 to the second quarter of 2009. Hedonic house price model, which is not reflecting spatial autocorrelation, has been a powerful tool in understanding housing market dynamics in urban housing economics. This study considers spatial autocorrelation in order to improve the traditional hedonic model which is based on OLS(Ordinary Least Squares) method. The study is, also, investigated the comparison in terms of $R^2$, Sigma Square(${\sigma}^2$), Likelihood(LR) among spatial econometrics models such as SAR(Spatial Autoregressive Models), SEM(Spatial Errors Models), and SAC(General Spatial Models). The major finding of the study is that the SAR, SEM, SAC are far better than the traditional OLS model, considering the various indicators. In addition, the SEM and the SAC are superior to the SAR.