• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.107-116
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• 2002

Crash Cushion is a kind of safety facilities on roadside which acts the role of absorbing impact energy when vehicles are driven out of normal route such as Gore area of freeway off ramp. Criteria for severity index considering accident occurrence possibility are needed to have strong effect on installing the facilities. However, present criteria for establishing crash cushion design do not include such processes. Therefore, the paper presents two kinds of study to develop criteria for severity index. First of all, development of accident forecasting model on freeway off ramp is presented. The module is a relationship between accidents and road environment by negative binomial distribution (NB) which is called to reflect very well quality of accidents at Gore of crash cushion installed freeway Secondly, freeway exiting behavior model is developed because the human factor is the most important one. However, many literatures have shown between road environment and accidents which are more quantitative than human factor. The study supposed advanced process steps on actual freeway and analysed correlation between variables and accidents. The criteria for severity index is presented to determine whether to install or not by benefit cost analysis for each module. The standard for severity index will help to determine whether to install the crash cushion or not and to estimate severity for freeway and off ramp.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.56-65
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• 2019

This study empirically analyzes the effect of weather on pedestrian volume in an urban space. We used data from the 2009 Seoul Flow Population Survey and constructed a model with the pedestrian volume as a dependent variable and the weather and physical environment as independent variables. We constructed 28 models and compared the results to determine the effects of weather on pedestrian volume by season, land use, and time zone. A negative binomial regression model was used because the dependent variable did not have a normal distribution. The results show that weather affects the volume of walking. Rain reduced walking volume in most models, and snow and thunderstorms reduced the volume in a small number of models. The effects of the weather depended on the season and land use, and the effects of environmental factors depended on the season. The results have various policy implications. First, it is necessary to provide semi-outdoor urban spaces that can cope with snow or rain. Second, it is necessary to have different policies to encourage walking for each season.

• Journal of the Korean Data Analysis Society
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• v.20 no.6
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• pp.2829-2840
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• 2018

The random variable with an arbitrary value or more is called semi-continuous variable or zero-inflated one in case that its boundary value is more frequently observed than expected. This means the boundary value is likely to be practically observed more than it should be theoretically under certain probability distribution. When the distribution considered is continuous, the variable is defined as semi-continuous and when one of discrete distribution is assumed for the variable, we regard it as zero-inflated. In this study, we introduce the two-part model, which consists of one part for modelling the binary response and the other part for modelling the variable greater than the boundary value. Especially, the zero-inflated regression models are explained by using Poisson distribution and negative binomial distribution. In real data analysis, we employ the zero-inflated regression models to estimate the number of days under extreme heat-wave circumstances during the last 10 years in South Korea. Based on the estimation results, we create prediction maps for the estimated number of days under heat-wave advisory and heat-wave warning by using the universal kriging, which is one of the spatial prediction methods.

• Journal of Korea Port Economic Association
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• v.38 no.2
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• pp.95-107
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• 2022

Shipping companies earn profits through cargo transportation, and therefore, investment decisions to purchase ships are more important than anything else. Nevertheless, the cash flow discount method was mainly used in the economic analysis method, which assumes that all situations are static. This study shows that the real option model is useful in the economic analysis of ship investment. This economic analysis took into account the irreversibility of investment and uncertainty of benefits. In particular, this study used a binary option price determination model among real options. In addition, the simulation was conducted using actual investment data of A shipping company. As a result of the analysis, the investment value of used ships according to the net present value method was analyzed as negative (-), but the investment value in the real option model reflecting the flexibility of decision-making was evaluated as having positive (+) economic feasibility. It was analyzed that economic feasibility is affected by profit volatility and discount rate. Therefore, this study is expected to help shipping companies make more flexible decisions by using the real option model along with the existing net present value method when making ship investment decisions.

• Culinary science and hospitality research
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• v.22 no.3
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• pp.240-253
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• 2016

The purpose of this study is to predict factors influencing participant demand for the temple stays and to help find alternatives for temple stay marketing strategies. Specifically, the study sought to examine input variables on the visit frequency of temple visitors who partook in temple food. Research subjects were temple stay participants with experience with temple food. Through convenience sampling method, 300 self-administered questionnaires were distributed to participants at 4 temple stays in Seoul. Of the 278 questionnaires collected, 232 (83%) were used for research analysis. Given that the requirement that proper model for analysing the collected data be applied, the Truncated Negative Binomial(TNB) Poisson model, which is useful for analysing count data that are truncated at '0' and overcrowded with a certain value, was selected fort his study. Study results found that, for temple stay food revitalization, the most crucial item for temple food proponents to recognize is natural food ingredients. The degree of affection was higher among respondents over 40 years of groups and with incomes over 40 million won or more than others. In addition, unmarried and male were higher than married and female, and the Christian population in the temple food demand higher impact than Shamanism community. This match should be a priority to establish an in-depth public relations policy of targeted marketing of consumers according to various demographic characteristics. Active and aggressive efforts to expand food inspection are required to promote the healthy image of the temple food to the fragmentation of consumer marketing hierarchy.

• The Journal of Information Systems
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• v.26 no.1
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• pp.1-19
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• 2017

Purpose This study examines the roles of individual- and country-level social capital in entrepreneurial activities from the context of crowdfunding. Design/methodology/approach Two primary sources were used for data collection. From Kickstarter, the largest U.S.-based crowdfunding platform, this study obtained 15,716 crowdfunding projects and individual-level social capital. For country-level social capital, the social capital index from the 2016 Legatum Prosperity Index was utilized. By matching individual- and country-level social capital for each crowdfunding project, this research estimates the role of social capital in entrepreneurial activities at the individual and country level using the Poisson regression and the negative binomial regression. Findings Individual-level social capital measured by the number of Facebook friends, the number of other crowdfunding projects that a crowdfunding project founder invested in, and the word count of the description of a crowdfunding project are positively associated with the number of crowdfunding projects created by founders. The country-level social capital measured by aggregated social capital index is also positively associated with the number of crowdfunding projects created by founders. Both individual- and country-level social capital have a positive impact on entrepreneurial activities in terms of the creation of new crowdfunding projects.

• Journal of Korean Society of Transportation
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• v.32 no.4
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• pp.369-379
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• 2014

The Statistical regression model has been used to construct crash prediction models, despite its limitations in assuming data distribution and functional form. In response to the limitations associated with the statistical regression models, a few studies based on non-parametric methods such as neural networks have been proposed to develop crash prediction models. However, these models have a major limitation in that they work as black boxes, and therefore cannot be directly used to identify the relationships between crash frequency and crash factors. A genetic programming model can find a solution to a problem without any specified assumptions and remove the black box effect. Hence, this paper investigates the application of the genetic programming technique to develope the crash prediction model. The data collected from the Gyeongbu expressway during the past three years (2010-2012), were separated into straight and curve sections. The random forest technique was applied to select the important variables that affect crash occurrence. The genetic programming model was developed based on the variables that were selected by the random forest. To test the goodness of fit of the genetic programming model, the RMSE of each model was compared to that of the negative binomial regression model. The test results indicate that the goodness of fit of the genetic programming models is superior to that of the negative binomial models.

• Journal of Technology Innovation
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• v.25 no.4
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• pp.165-187
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• 2017

This study analyzed the effects of TLO's organization size, expertise, and economic compensation on technology transfer performance using the panel data of Government-Funded Research Institutes in 2013-2016. First, the size of TLO personnel and budget have a positive effect on the technology transfer performance. However, in the case of TLO manpower, the statistical significance of the effect on the number of technology transfers was only 90%, and it did not affect royalty. Second, TLO expertise has a strong impact on technology transfer performance. It shows that the number of professional license holders, such as patent attorney or a technology valuer, has a statistically significant effect on the increase of the technology transfer number and the royalty under the 99% confidence level. However, unlike expected, the size of the Ph.D. did not seem to have any effect on technology transfer performance. Finally, the economic compensation for TLO does not affect both the number of technology transfers and the royalty. It does not seem to work as an appropriate incentive system, because the absolute size of the compensation is too small. The results of the above analysis suggest that it is important to secure expertise in order for the TLO organization to play a substantial role, and it is necessary to improve the economic compensation system to attract TLOs to technology transfer.

• Korean journal of applied entomology
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• v.52 no.3
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• pp.243-248
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• 2013

This study was conducted to understand the settlement process of Ascotis selenaria larvae into citrus orchards with respect to oviposition site and analysis of the spatial distribution pattern of the larvae. A. selenaria eggs were not found on citrus trees in field and green house, but not on citrus trees in the field. A. selenaria larvae showed a significant clump distribution in the greenhouse. In the open citrus field, the index of dispersion was around 1.0 in most cases, with a weak clumping degree. However, the d-statistic was between -1.96 and 1.96, indicating a statistically significant random distribution. In addition, the Green's index (a clumping index) was very low in all cases, even though the clump distribution was accepted. for most samples, the probability distribution of larval frequency in the field satisfied the probability distribution functions of Poisson (random pattern) and the negative binomial (clump pattern) distribution. In addition, the temporal distribution of the larvae in the open field showed a pattern which was formed by colonizers from outside oviposition sites. Further, the difference in larval spatial distribution between field and greenhouse orchards was discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.397-405
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• 2015

In the past, expressways focused on mobility. However, the paradigm of expressways fuction today has been changed from fast expressways to safe expressways as people's quality of living and consciousness level heightened. In 2012, 3,550 traffic accidents occurred on expressways and 371 people died. The fatality rate of traffic accidents on expressways is almost twice that on general national roads. This study developed accident forecast models (safety performance functions) based on the number of traffic accidents and traffic volumes on six major lines on expressways. It is difficult to forecast safety performance functions for each expressway line because the lines and the scales of expressways are different from each other; therefore, integrated safety performance functions of six lines were determined first, and the coefficients, which can correct the traffic accidents on each line, were calculated. It is believed that this study will contribute in the safer management of expressways by being used as basic information in the establishment of traffic safety strategies for each expressway line in prevention of traffic accidents. Moreover, more studies would be required in the future, which would suggest reliable accident forecasts by calculating correction coefficients by line through integrated models by groups dependent on the characteristics of each line.