• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.131-137
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• 2014

It is expected that there will be delay of scheduled transmission network reinforcement and huge investment of renewable energy resources in Korea. As transmission capacity expansion delayed, supplying power to Seoul metropolitan area will not be increased as scheduled. In addition, uncertain renewable energy out of Seoul metropolitan area can cause transmission congestion in the future power system. These two combining effects will make the difference in locational marginal prices(LMP) and congestion costs increase. In that sense, this paper will analyze how much the congestion costs for Korea power system are incurred in the future power system. Most of previous approaches to analyze the congestion costs for electric power system are based on the optimal power flow model which cannot deal with hourly variation of power system. However, this study attempted to perform the analysis using market simulation model(M-Core) which has the capability of analyzing the hourly power generation cost and power transmission capacity, and market prices by region. As a result, we can estimate the congestion costs of future power system considering the uncertainty of renewable energy and transmission capacity.

• Culinary science and hospitality research
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• v.14 no.1
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• pp.1-10
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• 2008

The purpose of this study was to measure the estimated coefficient and marginal willingness to pay of attribute level: origin logo, origin description, traditional food, fusion food, service guarantee, and price, which influence tourist preference for restaurants. Also, the study identified the attribute which confers the highest importance to tourists. Conjoint experiment and the ordinal probit model were used for this study. A total of 210 surveys were conducted by tourists. The findings from this study were as follows. First, the effects of all attributes on tourist preference for restaurants were statistically significant. Second, tourists regarded an origin logo as the very important attribute, and were more willing to pay for the case where the menu contained origin logo. These findings suggested new marketing opportunities for restaurant managers. Although this study provides some evidence on the value of the local product brand to tourists, a similar measure has not been developed for local residents. This is an area in need of future research.

• 한국데이터정보과학회:학술대회논문집
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• 2001.10a
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• pp.25-33
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• 2001

This paper suggests a generalized logit model with mixed effects for analysing frequency data in multi-contingency table. In this model nominal response variable is assumed to be polychotomous. When some factors are fixed but condisered as ordinal and others are random, this paper shows how to use baseline-category logits to incoporate the mixed-effects of those factors into the model. A numerical algorithm was used to estimate model parameters by using marginal log-likelihood.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.1
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• pp.124-130
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• 2009

Estimating genetic interaction effects in animal genomics would be one of the most challenging studies because the phenotypic variation for economically important traits might be largely explained by interaction effects among multiple nucleotide sequence variants under various environmental exposures. Genetic improvement of economic animals would be expected by understanding multi-locus genetic interaction effects associated with economic traits. Most analyses in animal breeding and genetics, however, have excluded the possibility of genetic interaction effects in their analytical models. This review discusses a historical estimation of the genetic interaction and difficulties in analyzing the interaction effects. Furthermore, two recently developed methods for assessing genetic interactions are introduced to animal genomics. One is the restricted partition method, as a nonparametric grouping-based approach, that iteratively utilizes grouping of genotypes with the smallest difference into a new group, and the other is the Bayesian method that draws inferences about the genetic interaction effects based on their marginal posterior distributions and attains the marginalization of the joint posterior distribution through Gibbs sampling as a Markov chain Monte Carlo. Further developing appropriate and efficient methods for assessing genetic interactions would be urgent to achieve accurate understanding of genetic architecture for complex traits of economic animals.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.9-17
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• 2022

Purpose: The purpose of this study is to investigate how open contacts impact the natural teeth and dental implant prostheses. Materials and Methods: Following criteria were used to select 20 implant crowns with open proximal contacts as the experimental group (Group A): the restorations were delivered in Chosun University Dental Hospital between 2008 and 2018, the restorations are in the posterior region, opposing teeth are fixed dental prostheses, neighboring teeth are sound natural teeth, the patient had been on the maintenance program for at least 3 years. Another 20 implant crowns with closed proximal contacts were selected as the control group (Group B) using the same criteria. Between the two groups, dental caries and food impaction of the neighboring natural teeth and marginal bone-loss of the implants were compared and evaluated. Results: There was no statistically significant difference between Group A and Group B in the occurrence rates of dental caries, food impaction, and marginal bone-loss. The amount of marginal bone-loss, however, revealed statistically significant differences between the two groups, with Group A showing 0.80 ± 0.39 mm loss and Group B showing 1.1 ± 0.43 mm loss. Conclusion: Implant prostheses with open contacts could be clinically considered in select cases as such restorations revealed no harmful effects on neighboring teeth and implant restorations within the perimeters of this study.

• Journal of Hydrogen and New Energy
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• v.22 no.3
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• pp.292-298
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• 2011

This study examines the effects of the ambient temperature (AT), methanol feeding temperature (MFT), methanol concentration (MC) and methanol flow rate (MFR) on the performance and cell temperature (CT) of a 5-stacked direct methanol fuel cell (DMFC). The AT, MFT, MC, and MFR are varied from $-10^{\circ}C$ to $+40^{\circ}C$, $50^{\circ}C$ to $90^{\circ}C$, 0.5M to 3.0M and 11.7 mL $min^{-1}$ to 46.8 mL $min^{-1}$, respectively. The performance of the DMFC under various operating conditions is analyzed from the I-V polarization curve, and the methanol crossover is estimated by gas chromatography (GC). The performance of the DMFC improves significantly with increasing AT. The open circuit voltage (OCV) decreases with increasing MC due to the enhanced likelihood of methanol crossover. The cell performance is improved significantly when the MFR is increased from 11.7 mL $min^{-1}$ to 28.08 mL $min^{-1}$. The change in cell performance is marginal with further increases in MFR. The CT increases significantly with increasing AT. The effect of the MFT and MFR is moderate, and the effect of MC is marginal on the CT of the DMFC.

• Journal of Digital Convergence
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• v.13 no.9
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• pp.137-148
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• 2015

The objectives of this study identify the factors that affect the quality of MTS services, to determine the effects of these service quality factors on customer's satisfaction and customer's loyalty. The results are as follows: First, The Four factors, i.e., tangibles, reliability, responsiveness, and assurance, represent statistically marginal significance in explaining the relationship between MTS service quality factors and customer's satisfaction. Second, The Five factors, i.e., rapidness, tangibles, responsiveness, empathy, and assurance represent statistically marginal significance in explaining the relationship between MTS service quality factors and customer's loyalty. Third, There are some differences in assurance/period of utilization, empathy/period of utilization in using MTS services according to social statistics. This article provides the paradigm of new convergence on IT and finance.

• Journal of Climate Change Research
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• v.8 no.3
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• pp.213-220
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• 2017

The purpose of this study is to analyze effects of Greenhouse Gas (GHG) emission reduction in district energy business mainly based on Combined Heat and Power (CHP) plants. Firstly this paper compares the actual carbon intensity of power production between conventional power plants and district energy plants. To allocate the GHG from CHP plants, two of different methods which were Alternative Generation Method and Power Bonus Method, have been investigated. The carbon intensity of power production in district energy plants ($0.43tonCO_2e/MWh$) was relatively lower than conventional gas-fired power plants ($0.52tonCO_2e/MWh$). Secondly we assessed the cost effectiveness of reduction by district energy sector compared to the other means using TIMES model method. We find that GHG marginal abatement cost of 'expand CHP' scenario (-$134/ton$CO_2$) is even below than renewable energy scenario such as photovoltaic power generation ($87/ton$CO_2$). Finally the GHG emission reduction potential was reviewed on the projected GHG emission emitted when the same amount of energy produced in combination of conventional power plants and individual boilers as substitution of district energy. It showed there were 10.1~41.8% of GHG emission reduction potential in district energy compared to the combination of conventional power plants and individual boilers.

• Journal of Korea Technology Innovation Society
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• v.10 no.1
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• pp.1-21
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• 2007

Among numerous policy influencers' and researchers' advices and policy suggestions, there is little opposition to the proposition that technology is essential to the economic development. The role of technology has never been more emphasized than today in Korea as in any other countries. The effects of the government's innovation policy on corporate R&D activities and more broadly the economic welfare of a whole nation are widely recognized with intuitional and empirical evidence. That is, various R&D incentives reduce the marginal cost of a firm's R&D efforts, inducing as much increase of its R&D investment to result in a better chance to acquire target technology. This paper examines the impact of R&D incentives on the technological outcomes by analyzing individual firms' investment behaviors subject to the government's R&D incentive policies. An econometric model of technological outcomes is estimated on a project level with cross-sectional data. "Probit model" is employed for estimations. Special attention was given to the effectiveness of R&D programs by estimating policy impact by types of investment. The data were collected from 928 different R&D projects completed between 1987 and 1993. With the single equation approach, we were able to find that the structure of investment is a far more significant factor in technological outcomes than the total amount of investment. The analysis also shows that the two types of firms' matching investment, in-kind and cash, do not bear a complementary, but a substitutive relations to each other. It also reconfirms the proposition that R&D incentives increase firm's financial investment. Despite many supportive studies emphasizing the cooperation between innovation performers, it is also found that the larger the number of institutions involved in a project, the less likely it leads to a technological success, And meeting the proposed deadlines without postponing is estimated to be a good barometer to predict the outcome of an R&D project. Also the probabilities of success for major variables are represented for policy implications, after calculating marginal effects.

• KDI Journal of Economic Policy
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• v.38 no.3
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• pp.79-106
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• 2016

This paper investigates the effectiveness of public credit guarantee programs and interest-support programs for SMEs (small and medium enterprises). First, assuming that there is an imperfect information structure in the SME loan market, we analyze how SME support financial programs affect the corporate decisions made by SMEs with regard to default or loan sizes. In addition, this paper theoretically computes the optimal levels of credit guarantee amounts and the interest-support spread under equilibrium with imperfect information in a competitive loan market. Second, the paper empirically analyzes the continuous policy-treatment effect with the GPS (generalized propensity score) method. In particular, we consider the ratio of guaranteed debt to the total debt as a continuous policy treatment. The empirical results show that marginal effects of a credit guarantee on SMEs' productivity, profitability, and growth potential decrease with the ratio of guaranteed debt to the total debt. In addition, the average effect of a credit guarantee is maximized when this ratio is at 50% to 60%.