• Proceedings of the Korea Technology Innovation Society Conference
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• 1999.11c
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• pp.331-340
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• 1999

국제원유가격의 변동은 세계 각국의 경제에 상당한 영향을 미치고 있다. 이러한 원유가격의 변동을 정확히 예측하기 위해서는 원유가격 변동요인의 정립이 필히 요구된다. 본 연구에서는 전통적으로 원유가격의 중요한 변동요인으로 알려져 있는 OPEC의 원유생산량과 걸프전쟁 이후 주요한 국제원유가격 변동요인으로 알려져 있는 OPEC의 원유생산량과 걸프 전쟁 이후 주요한 국제원유가격 변동요인으로 주목받고 있는 미국의 원유재고량의 영향과 역할을 공적분(Cointegration) 모형과 오차수정모형(Error-Correction Model)을 통해 분석하였다. 분석결과, 원유생산량과 더불어 원유재고량도 원유가격의 중요한 변동요인으로 작용함을 알 수 있었다. 장·단기 탄력성의 경우, 원유생산량의 생산탄력성은 단기에 비해 장기에 더 탄력적으로 나타났으며 장기에는 원유재고량의 변동이 생산량의 변동보다 오히려 원유가격에 더 큰 영향을 미치는 것으로 나타났다. 또한, 원유가격은 첫해에서 나타난 불균형을 대략 12%의 조정속도로, 장기균형으로 조정됨을 알 수 있었다.

• The Korean Journal of Applied Statistics
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• v.13 no.2
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• pp.393-405
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• 2000

Box and Draper( 19(5) listed some properties of a design that should be considered in design selection. But it is impossible that one design criterion from optimal experimental design theory reflects many potential objectives of an experiment, because the theory was originally based on the underlying model and its strict assumption about the error structure. Therefore, when it is neces::;ary to implement multi-objective experimental design. it is common practice to balance out the several optimal design criteria so that each design criterion involved benefits in terms of its relative "high" efficiency. In this study, we proposed several composite design criteria taking the case of heteroscedastic model. WVhen the heteroscedasticity is present in the model. the well known equivalence theorem between 1)- and C-optimality no longer exists and furthermore their design characteristics are sometimes drastically different. We introduced three different design criteria for this purpose: constrained design, combined design, and minimax design criteria. While the first two methods do reflect the prior belief of experimenter, the last one does not take it into account. which is sometimes desirable. Also we extended this method to the case when there are uncertainties concerning the error structure in the model. A simple algorithm and concluslOn follow.On follow.

• The Korean Journal of Applied Statistics
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• v.13 no.2
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• pp.457-476
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• 2000

In this study, we have proposed a sampling method and an estimation method for efficiently estimating the mean of a population which has a linear trend. These methods involve drawing a sample by the so-called "centered balanced systematic sampling", which is an extension of systematic sampling, and then estimating the population mean with an adjusted estimator, not with the sample mean itself. We used the concept of interpolation in determining the adjusted estimator.\Ve compared the efficiency of the proposed estimator with those of the estimators from existing methods, under the expected mean square error criterion based on the infinite superpopulation model introduced by Cochran(1946). The proposed method is for use in the case when the sample size n(2 5) is an odd number and k(the reciprocal of the sampling fraction) is an even number. A good result was also obtained in an example using computer simulation. simulation.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.123-131
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• 2011

This study proposes a model for road surface temperature prediction on basis of the heat-energy balance equation between atmosphere and road surface. The overall model is consisted of two types of modules: 1) Canopy 1 is used to describe heat transfer between soil surface and atmosphere; and 2) Canopy 2 can reflect the characteristics of pavement type. Input data used in the model run is obtained from the Korea Meteorological For model validation, the observed and predicted surface temperature data are compared using data collected on MoonEui Bridge along CheongWon-Sangju Expressway, and the comparison is made on winter and other seasons separately. Analysis results show that average difference between two temperatures lies within ${\pm}2^{\circ}C$ which is considered as appropriate from a micrometeorology point of view. The model proposed in this paper can be adopted as a useful tool in practical applications for winter maintenance. This study being a fundamental research is anticipated to be a starting point for further development of robust surface road temperature prediction algorithms.

• Journal of Environmental Policy
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• v.12 no.3
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• pp.97-122
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• 2013

The ARDL(Autoregressive Distributed Lag) method is employed analyzes the long-run equilibrium relationships among environmental pollution($CO_2$ emissions) per capita, income levels per capita, and energy consumption per capita. The error correction model is employed to analyze the short-term effects of income and energy consumption on $CO_2$ emissions. The Toda-Yammamoto method is employed for causal analysis among the three variables. The results show that income levels, energy consumption, and $CO_2$ emissions are cointegrated. We found the N type relationship between income and $CO_2$ emissions. Long-term elasticities of income and energy consumption with respect to $CO_2$ emission were greater than their short-term elasticities. There were a bilateral causality between energy consumption and $CO_2$ emissions. There was a unilateral causality from $CO_2$ emissions to income and from energy consumption to income not vice versa. Energy consumption can be an important variable to contribute to forecasting $CO_2$ emissions.

• Journal of Korean Society of Forest Science
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• v.97 no.4
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• pp.458-466
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• 2008

This study was carried out to forecast long-term supply and demand of chestnut and to analyze the impacts of change in the environment of domestic and international chestnut markets. For these ends, the study developed a partial equilibrium market model, in which in-shelled chestnut market was vertically linked to shelled chestnut market. To examine the predictive ability of the model for the endogenous variables ex-post simulation was run for the period 1990 through 2003. In general, all endogenous variables reproduced the historical trends during the period except for disuse areas and newly established areas. The results of forecasting supply and demand show that domestic in-shelled chestnut production is estimated to decrease slightly from 76,447 ton in 2005 to 76,286 ton in 2020 and that exports of shelled chestnut continue to be decreased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2C
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• pp.112-118
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• 2011

In this paper, we conduct an objective performance analysis of the crosstalk cancellation scheme studied in [11]. While the conventional scheme is only applicable to a listener on the optimal listenable region (sweetspot), the space skew/crosstalk cancellation (SS/CC) scheme in [11] can mitigate crosstalk regardless of the listener's position by using listener position tracking (LPT) system. The SS/CC scheme is composed of two parts: LPT-based SS and CC parts. In this paper, the SS/CC scheme is evaluated by some criteria such as follows: condition number, and the balance characteristic, its root mean square error, and running average.

• Journal of Technology Innovation
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• v.25 no.1
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• pp.61-89
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• 2017

This study aims to estimate empirically the respective impacts of R&D expenditure, R&D labor, overseas direct investment, commodity trade balance, and technology trade openness on technology balance of payments. To examine the presence of co-integration between them, this paper employed the ARDL-bounds test using time series data from 1981 to 2014, and the result shows that there is a stable long-run equilibrium relationship among them. Furthermore, we estimated long- and short-run coefficients of the technology balance of payments with respect to each variables based on long-run equilibrium equation and error correction model. As a result, the technology balance of payments respond negatively to R&D labor and technology trade openness, and R&D expenditure does produce positive effects in the long-run, while coefficients of overseas direct investment and commodity trade balance in the long-run are not statistically significant. Besides, according to results of error correction model, overseas direct investment only has clearly a positive effects in the short-run, in contrast, the short-term relationships between the other variables and the technology balance of payments could not definitively derived. This implies that it is necessary to procure and cultivate talented personnel, as well as to enlarge gradually technology trade size in order to improve technology balance of payments from a long-term point of view.

• The Korean Journal of Financial Management
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• v.23 no.1
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• pp.49-67
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• 2006

This study examines whether won/dollar futures have price discovery function and volatility spillover effect or not, using intraday won/dollar futures prices, volumes, and spot rates for the interval from March 2, 2005 through May 30, 2005. Futures prices and spot rates are non-stationary, but there is the cointegration relationship between two time series. Futures returns, spot returns, and volumes are stationary. Asymmetric effects on volatility in futures returns and spot returns does not exist. Analytical results of mean equations of the BGARCH-EC (bivariate GARCH-error correction) model show that the increase of futures returns raise spot returns after 5 minutes, which implies that futures returns lead spot returns and won/dollar futures have price discovery function. In addition, the long-run equilibrium relationship between the two returns could help forecast spot returns. Analytical results of variance equations indicate that short-run innovations in the futures market positively affect the conditional variances of spot returns, that is, there is the volatility spillover effect in the won/dollar futures market. A dummy variable of volumes does not have an effect on two returns but influences significantly on two conditional variances.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.6
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• pp.109-115
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• 2014

Sales of online games companies that began from the small and medium-sized ventures, have grown to billions or hundreds of million dollars to target the global market. The issues related with industrial policies and regulations for game industry gain attentions. In particular, the Korean government has strengthened the relevant regulations of the webboard game service across many departments within the government such as Media Rating Commission, Game Products Administrative Committee, Ministry of Culture, Tourism and Sports, and Ministry of Female and Family. In this study, we analyze the effects of government regulation on webboard games using a VECM(Vector Error Correction Model). We have acquired the Gametrix time-series data during a year since July 2013. Having the co-integration estimated in the analysis process, we attempt to identify the long-term equilibrium relationship within webboard game industry and predict use time in near future. The results show that the use time has decreased to a third to a fourth comparing to the initial value at the beginning point in 2013. Two representative webboard games are exposed to the significant risks to have less or no use time. Additionally, we discuss the issues of the overall game industry influenced by the changes of webboard games.