• Journal of Distribution Science
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• v.17 no.3
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• pp.85-95
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• 2019

Purpose - The existing marketing studies using Social Network Analysis have assumed that network structure variables are time-invariant. However, a node's network position can fluctuate considerably over time and the node's network structure can be changed dynamically. Hence, if such a dynamic structural network characteristics are not specified for virtual goods purchase model, estimated parameters can be biased. In this paper, by comparing a time-invariant network structure specification model(base model) and time-varying network specification model(proposed model), the authors intend to prove whether the proposed model is superior to the base model. In addition, the authors also intend to investigate whether coefficients of network structure variables are random over time. Research design, data, and methodology - The data of this study are obtained from a Korean social network provider. The authors construct a monthly panel data by calculating the raw data. To fit the panel data, the authors derive random effects panel tobit model and multi-level mixed effects model. Results - First, the proposed model is better than that of the base model in terms of performance. Second, except for constraint, multi-level mixed effects models with random coefficient of every network structure variable(in-degree, out-degree, in-closeness centrality, out-closeness centrality, clustering coefficient) perform better than not random coefficient specification model. Conclusion - The size and importance of virtual goods market has been dramatically increasing. Notwithstanding such a strategic importance of virtual goods, there is little research on social influential factors which impact the intention of virtual good purchase. Even studies which investigated social influence factors have assumed that social network structure variables are time-invariant. However, the authors show that network structure variables are time-variant and coefficients of network structure variables are random over time. Thus, virtual goods purchase model with dynamic network structure variables performs better than that with static network structure model. Hence, if marketing practitioners intend to use social influences to sell virtual goods in social media, they had better consider time-varying social influences of network members. In addition, this study can be also differentiated from other related researches using survey data in that this study deals with actual field data.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.50-59
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• 2015

This study aimed at suggesting Willingness To Pay (WTP) for introduction of the Traffic Accident emergency Call (TAC) system by using Contingent Valuation Method (CVM) which is a general valuation method. As the method, this study suggested a WTP estimation method of the TAC system with the double-bound dichotomous choice model. In previous studies, the data are processed differently according to the type of questions and analysis models used for the calculation of willingness to pay. Therefore, we re-organized the model by the cases using the truncated data sets, and showed the difference in WTPs. The dataset was developed by more than 500 questionnaire obtained from online and offline survey with the consideration of composition ratio by age group referring housing census in 2010 to mitigate regional bias of samples. At last, this study applied various statistical methods, survival analysis, multiple regression, and Tobit model for better interpretation of the questionnaires.

• The Korean Journal of Financial Management
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• v.25 no.4
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• pp.183-212
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• 2008

The purpose of this paper is to analyze the efficiency change and determinants of the korean non-life insurance companies. we use DEA (Data Envelopment Analysis) model to measure company efficiency change and use GLS, Tobit model, FIixed effect model, Random effect model, GMM to measure efficiency determinants. we utilize ten non-life insurance companies in korea and the panel data for five from 2001 to 2005. The empirical results show the following findings. First, technical efficiency shows that approximately 15.5% of inefficiency exists on the non-life insurance companies and it reveals that the cause for technical inefficiency is due to scale inefficiency. Second, Dea Window results show that the stable dissimilarity by standard deviation, LDP of CCR. Third, the results of efficiency determinants show that increase efficiency is depend on the premium income and real estates.

• Journal of Korea Water Resources Association
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• v.40 no.11
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• pp.861-867
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• 2007

This Research analyzes the consumers' willingness to pay(WTP) for residential water on severe drought condition. The 7 large cities and 32 chronicle drought regions have been selected for this research survey. Results show that the consumers of large cities, which are relatively rich, think water quality is more important than quantity, but the consumers of 32 chronicle drought regions expressed just opposite. Dichotomous choice and open-ended questionnaire are mixed for the survey and Tobit model is applied in the analysis. As we expected, the higher the education level, the number of household member, and the income, the higher the WTP. When there is 25% reduction of supply, the WTP is about $2 per month. Contrary to the expectation, WTP is just slightly increased for 50% of water supply reduction. This is because of the resistance of tax as well as the limited actual experiences of water shortage so, they underestimated it. In any cases, actual WTP for actual water shortage is much higher than this result. More effective water supply and distribution schedule must be ready as a national and local level to prepare severe drought in the near future. Consumers are willing to pay higher price than the current level for water security. Water distributional system should be reconsidered and alternative source of water also be prepared.

• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.129-138
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• 2016

Shipping companies involved in sea transportation service are exposed to uncertainty due to its volatile business environment. It is crucial that shipping companies take effective strategies to cope with uncertain business environments and to achieve high business performance. Using Porter's generic strategy, this study investigates the relationships between environmental uncertainty and competitive strategies, and the impact of competitive strategies on firm's business performance. To test hypotheses, OLS regressions and Tobit analysis were conducted on Korea shipping companies who provide global sea transportation service. The findings of this study can be summarized as follows. First, variation of environmental uncertainty affects cost-leadership strategy and differentiation strategy. Diversity of environmental uncertainty affects differentiation strategy, but not cost-leadership strategy. Second, firms attain business performance by using the cost-leadership strategy. That is, shipping companies can achieve high business performance by reducing their operating costs in the entire process of transportation service.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.987-994
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• 2015

This study examines how single-person household expenditure patterns are different with respect to age and income groups using Tobit model. The expenditure data of the national household survey from 2006 to 2012 were used. The results show that income elasticities of all items are greater than 1 except for food & beverage, housing, water, electricity & gas, and Communication. Income elasticities are significantly different among consuming items. Additionally the income elasticities are also different between various age and income groups of single-person households. Therefore governments and businesses have to take this into account when devising their policies or strategies regarding single-person households. Especially, businesses need to adopt a strategy targeted at single-person households with high income and buying power such as unmarried professional people. As the number of single-person household increases the proportion of expenditures on necessities such as beverage, food, and energy is expected to decrease while that on services increases. Consequently policy responses are required to prepare for the expansion of service industries such as health, hospital, and housekeeping services.

• Korean small business review
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• v.42 no.4
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• pp.147-172
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• 2020

This study presents the determinants of R&D efficiency as the focus on CEO's competency, which influences R&D competency and R&D efficiency. The research samples are 6,708 technology-innovation small and medium-sized enterprises (SMEs). The independent variable is the R&D competency(existence of R&D organization, level of R&D personnel, R&D personnel management, R&D investment), the dependent variable is R&D efficiency. The moderator is the CEO's competency(experience level in its own industry, technical knowledge level, technology management strategy, management ability). R&D efficiency measures the relationship between inputs(level of R&D personnel, R&D investment) and outputs(patent applications, prototype) by the DEA. and the determinant analysis uses Tobit regression. As a result of the analysis, the existence of R&D organization and R&D personnel management is positively significant, level of R&D personnel and R&D investment is negatively significant for R&D efficiency. The moderating effect of CEO's competency on the relationship between the R&D competency and R&D efficiency is significant determinants of CEO's experience(experience level in its own industry, technical knowledge level) and technology management strategy. The finding is to measure the efficiency of R&D performance, and to analyze its determinants as the moderating effect of CEO's competency, using the technology appraisal data. In the conclusion session, the limitations of the research and future research directions were discussed.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.1
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• pp.71-82
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• 2023

As an alternative to solving social problems, social economic actors are attracting attention as an important alternative. SPC is a private program that pays incentives according to the social performance measured by monetary value. This study measured efficiency by applying DEA to social enterprises that participated in the SPC program and analyzed the factors affecting efficiency through tobit regression. As a result of DEA analysis, it was found that 21% of social enterprises participating in SPC were efficient, but 66% needed to improve their efficiency. In the Tobit regression analysis, the efficiency was relatively low in the case of manufacturing sector, and when the square term of sales is included, the efficiency decreases as sales increase. Through this, it was estimated that external support is needed at a low level sales before crossing the critical point, and that the efficiency of social value creation increases when it grows above a certain level. Moreover, it is significant in that it combines the variables used in the analysis of traditional industrial efficiency while conducting efficiency analysis focusing on the social performance by monetary value, which is considered the most important achievement of social enterprises. It is believed that it will contribute to research related to the environment creation and the requirements of each field in creating social values for social enterprises in the future.

• The Journal of Korean Medicine
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• v.35 no.3
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• pp.22-31
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• 2014

Objectives: The aim of this study was to identify the complementary and substitute relationships between the use of Korean medicine (KM) and that of Western medicine (WM) in the treatment of musculoskeletal disease. Methods: We analyzed the 2009 Korea Health Panel dataset. General characteristics and the medical utilization of respondents were analyzed descriptively. Logistic regression, negative binominal regression, and Tobit regression analysis were used to identify the relationships between the use of KM and the use, visit frequency, and expenses of WM, respectively. Results: In the treatment of musculoskeletal disease, KM use and non-herbal treatments with Korean medicine significantly reduced WM use. Herb medication use significantly increased WM visit frequency. There were no significant relationships between KM use and WM expenses. Conclusions: There are substitute relationships between WM use and KM use, especially non-herbal treatments in KM. Therefore we need to develop the clinical protocols of KM and WM treatments in the treatment of musculoskeletal disease for proper distribution medical resources.

• Journal of Distribution Science
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• v.15 no.10
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• pp.41-50
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• 2017

Purpose - Online product review has become a crucial part of the online retailer's market performance for a wide range of products. This research aims to investigate how an individual reviewer's review frequency and timing affect her/his average attitude toward products. Research design, data, and methodology - To conduct reviewer-level analysis, this study uses 42,172 posted online review messages generated by 6,941 identified reviewers for 59 movies released in the South Korea from July 2015 to December 2015. This study adopts Tobit model specification to take into account the censored nature and the selection bias arising from the nature of J-shaped distribution of movie rating. Results - Our estimation results support that the negative impact of review frequency and timing on valence. Furthermore, review timing has an inverted-U relationship with the user's average valence and enhance the negative effect of review frequency. Conclusions - This study contributes to the growing literature on the understanding how eWOM is generated at the individual consumer level. On the basis of the main empirical findings, this study provides insights into building a recommendation system in online retail store based on the consumer's review history data - frequency, timing, and valence.