• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.242-250
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• 2019

In this paper, we propose a method to predict the failure of industrial robot using Seq2Seq (Sequence to Sequence) model, which is a model for transforming time series data among Artificial Neural Network models. The proposed method uses the data of the joint current and angular value, which can be measured by the robot itself, without additional sensor for fault diagnosis. After preprocessing the measured data for the model to learn, the Seq2Seq model was trained to convert the current to angle. Abnormal degree for fault diagnosis uses RMSE (Root Mean Squared Error) during unit time between predicted angle and actual angle. The performance evaluation of the proposed method was performed using the test data measured under different conditions of normal and defective condition of the robot. When the Abnormal degree exceed the threshold, it was classified as a fault, and the accuracy of the fault diagnosis was 96.67% from the experiment. The proposed method has the merit that it can perform fault prediction without additional sensor, and it has been confirmed from the experiment that high diagnostic performance and efficiency are available without requiring deep expert knowledge of the robot.

• The Journal of Industrial Distribution & Business
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• v.10 no.2
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• pp.65-75
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• 2019

Purpose - Along with Chinese exchange rate's reform advancement, the issue of exchange rate of RMB has increasingly become the heated focus in the world. In July 2005, China carried out the reform of the exchange rate system, and this behavior has aroused the attention of the world. However, the dispute on whether the theory of purchasing power parity holds or not in China still exists. As such, this paper will attempt to explore whether the purchasing power parity is significant in China. Research design, data, and methodology - The monthly data from July 2005 to December 2017 will be employed to analyze the nominal exchange rate of RMB against the US dollar and the nominal exchange rate of RMB against the euro. Based on these datum, an empirical analysis will be conducted under the unit root test and the cointegration test to exploit the significance of purchasing power parity in China. Results - The findings of this paper reveal that an increase in China's consumer price index will lead to an increase in the RMB exchange rate, which will lead to the depreciation of RMB. Concomitantly, an increase in the consumer price index in the US and Europe will result in a decrease in the RMB exchange rate, which will lead to an appreciation of RMB. In general, in terms of the US, if US consumer price index increases by 1%, China's nominal exchange rate against US dollar will decrease by 0.905%; if China's consumer price index increases by 1%, China's nominal exchange rate against US dollar will increase by 0.648%. In terms of Europe, if Europe consumer price index increases by 1%, China's nominal exchange rate against euro will decrease by 0.277%; If China's consumer price index increases by 1%, China's nominal exchange rate against euro will increase by 0.235%. Conclusions - Generally speaking, the empirical evidences this paper provided show that the purchasing power parity theory has a certain explanatory ability for the decision of RMB exchange rate. As such, the purchasing power parity cannot hold completely, and China's government should continue to deepen the reform of the exchange rate system to improve China's exchange rate market.

• Journal of Korea Port Economic Association
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• v.26 no.1
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• pp.61-82
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• 2010

The purpose of this study is to examine the causuality among export and import trading volume of port of Busan, Kwangyang, Incheon and to induce policy implications. In order to test whether time series data is stationary and the model is fitness or not, we put in operation unit root test, cointegration test. And We apply Granger causality and impulse response and variance decomposition based on VECM. The results indicate that the trading volume of port of Busan is not largely influenced by that of port of Kawangyang and Incheon, but the trading volume of port of Kawangyang and Incheon is largely influenced by other ports including port of Busan. The result suggest that government has to focus on policy that the port of Kawangyang and Incheon can raise its own competitiveness in the world market.

• Journal of Korea Port Economic Association
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• v.23 no.1
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• pp.1-18
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• 2007

The purpose of this study is to examine the effect of exchange rate volatility on Trading Volume of Container of Korea, and to induce policy implication in the contex of GARCH and regression model. In order to test whether time series data is stationary and the model is fitness or not, we put in operation unit root test, cointegration test. And we apply impulse response functions and variance decomposition to the structural model to estimate dynamic short run behavior of variables. The major empirical results of the study show that the increase in exchange rate volatility exerts a significant negative effect on Trading Volume of Container in long run. The results Granger causality based on an error correction model indicate that uni-directional causality between trading volume of container and exchange rate volatility is detected. This study applies impulse response function and variance decompositions to get additional information regarding the Trading Volume of Container to shocks in exchange rate volatility. The results indicate that the impact of exchange rate volatility on Trading Volume of Container is negative and converges on a stable negative equilibrium in short-run. Th exchange rate volatility have a large impact on variance of Trading Volume of Container, the effect of exchange rate volatility is small in very short run but become larger with time. We can infer policy suggestion as follows; we must make a stable policy of exchange rate to get more Trading Volume of Container

• Journal of Energy Engineering
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• v.29 no.1
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• pp.1-12
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• 2020

The rapid climate change is strengthening carbon emissions regulations internationally. Korea is strongly pressed to accept the obligation to reduce greenhouse gases as one of the United Nations Framework Convention on Climate Change. This article analyzed the Granger causalities among environmental regulation, economic growth, electricity consumption, and CO₂ emission in Korea, using unit root test, cointegration test, and vector error correction model. As the results, environmental regulation has shown the bidirectional causalities with electricity consumption and CO₂ emission, while being unilaterally affected by economic growth in the long-run and strong relationship. Economic growth has affected electricity consumption, CO2 emission, and environmental regulation in the long-run, in the complex structure of the unilateral and short-run causality with electricity consumption and the bidirectional causality with CO2 emission. The policy implications will be as follows: ① environmental regulation should induce sustainable growth through encouraging technological innovation relating to CO2 reduction and productivity enhancement. ② Responding to the international CO2 reduction regulation, the synthetic policy initiatives will be considered to make synergy effects among policies relating to economic growth, electricity consumption.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.357-368
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• 2012

The purpose of this study is to empirically examine the impact of enterprise R&D investment on international trade in Korea under the new Normal Era. In order to test whether the time series data of trade variables are stationary or not, we put in operation unit root test and cointegration test. Based on VECM (Vector Error Correction Model), we also apply impulse response functions and variance decomposition to estimate the dynamic effects in the short-run and long-run. The results show that the relationship between enterprise R&D investment and international trade (export and import) exists in the long-run as well as in the short-run. The results of applying impulse response functions and variance decomposition also indicate that the impact of enterprise R&D investment on international trade is positive, and a significant portion of fluctuations in the trade variable is explained by enterprise R&D investment. Therefore, enterprise R&D investment must be continuously increased to improve economic growth with promoting trading competition power in Korea under the new Normal Era.

• Journal of Technology Innovation
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• v.31 no.2
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• pp.59-82
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• 2023

The purpose of this research is to conduct the empirical analysis of the short- and long-term causal relationship between public R&D investment, corporate R&D investment, and university R&D investment on economic growth in Korea. To this end, based on the time series data from 1976 to 2020, a causality test was conducted through the unit root test, cointegration test, and vector error correction model (VECM). As a result, it was found that there is a long-run equilibrium relationship between economic growth in Korea, public R&D investment, corporate R&D investment, and university R&D investment, in which a causal relationship exists in the long run. Also, while public R&D investment has a short-term effect on economic growth, corporate and university R&D investment does not have a short-term effect on economic growth. In addition, the results shows that there is a bidirectional causal relationship between economic growth and public R&D investment, corporate R&D investment and public R&D investment, and university R&D investment and public R&D investment in the short term. Through this research, it was empirically found that a highly mutual relationship exists between public R&D investment, corporate R&D investment, university R&D investment and economic growth. In order to increase the ripple effect of R&D investment on economic growth in the future, R&D investment between universities and corporations should be mutually promoted, and R&D investment by corporations should have a positive effect on public R&D investment so that public R&D investment can contribute to future economic growth.

• Journal of Korean Society of Transportation
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• v.34 no.1
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• pp.95-106
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• 2016

Air transportation demand is consistently increasing in Korea due to economic growth and low cost carriers. For this reason, airport expansion plans are being discussed in Korea. Therefore, it is essential to forecast reliable air transportation demand with adequate methods. However, most of the air transportation demand models in Korea has been developed by simple regression analysis with several dummy variables. Simple regression analysis without considering stationarity of time-series data can bring spurious outputs when a direct causal relationship between explanatory variables and dependent variable does not exist. In this paper, econometric model were developed for air transportation demand based on stationarity in time-series data. Unit root test and co-integration test are used for testing hypothesis of stationarity.

• Korean Journal of Construction Engineering and Management
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• v.16 no.2
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• pp.46-53
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• 2015

Electrical construction cost index is composed of the cost of albor and material. The producer price index is used to the cost of material. The Bank of Korea restructured the formation method and the basic period of the producer price index in 2013. Because fixed-weighted method can't faithfully reflect industrial structure changes. The weighted value and price index of fixed-weighted method is fixed on the basicp eriod. Electrical construction cost index is changed from fixed-weighted method to chain-weighted method in september 2014, because of these on the need. But the change of organization in formation method changes the weighted value. So there is the need of analysis about the statistical continuity of electrical construction cost index. This study is focused on the time series analysis between fixed-weighted and chain-weighted electrical construction cost index. We uses unit root test, cointegration test, regression analysis of long and short term equation, fitness for the estimation of static forecast as time series analysis. We verify that chain-weighted electrical construction cost index can be replaced to fixed-weighted construction cost index accounting analyses result. So users of it recognize that chain-weighted electrical construction cost index has statistical continuity.

• International Commerce and Information Review
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• v.17 no.1
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• pp.217-240
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• 2015

This paper uses the modified gravity model of international trade to examine the impact of ODA on the export of Korea to 28 aid recipients. In this perspective, the study includes recipient's economic size, trade openness, population, donor's scale of aid and distance between them as key determinants of the export of Korea by using panel data over the period of 2005-2012. To do this task, important econometric methods are fulfilled to test the model adequately, such as panel unit root and panel co-integration test. In addition, the study incorporated the panel OLS, panel GLM and panel EGLS methods. The empirical analysis clearly showed that an increase in Korea's ODA promotes its own exports. The coefficients of recipients's per capita GDP, population and trade openness have a positive impact on Korea's export respectively, while distance between them has a negative impact. Regarding regional dummy variables, aid for the region of Africa and America have a negative impact on Korea's export. Overall, the main implication of this study is that even if it emphasized Korea's economic interests as determinants of ODA disbursements, but it also suggests that an improvement of recipient's economic development, income distribution and educational environment can be an important concern in the future.