• Journal of Korea Port Economic Association
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• v.37 no.4
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• pp.161-173
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• 2021

The shipping industry plummeted and was depressed due to the global economic crisis caused by the bankruptcy of Lehman Brothers in the US in 2008. In 2020, the shipping market also suffered from a collapse in the unstable global economic situation due to the COVID-19 pandemic, but unexpectedly, it changed to an upward trend from the end of 2020, and in 2021, it exceeded the market of the boom period of 2008. According to the Clarksons report published in May 2021, the decrease in cargo volume due to the COVID-19 pandemic in 2020 has returned to the pre-corona level by the end of 2020, and the tramper bulk carrier capacity of 103~104% of the Panamax has been in the ports due to congestion. Earnings across the bulker segments have risen to ten-year highs in recent months. In this study, as factors affecting BDI, the capacity and congestion ratio of Cape and Panamax ships on the supply side, iron ore and coal seaborne tonnge on the demand side and Granger causality test, IRF(Impulse Response Function) and FEVD(Forecast Error Variance Decomposition) were performed using VAR model to analyze the impact on BDI by congestion caused by strengthen quarantine at the port due to the COVID-19 pandemic and the loading and discharging operation delay due to the infection of the stevedore, etc and to predict the shipping market after the pandemic. As a result of the Granger causality test of variables and BDI using time series data from January 2016 to July 2021, causality was found in the Fleet and Congestion variables, and as a result of the Impulse Response Function, Congestion variable was found to have significant at both upper and lower limit of the confidence interval. As a result of the Forecast Error Variance Decomposition, Congestion variable showed an explanatory power upto 25% for the change in BDI. If the congestion in ports decreases after With Corona, it is expected that there is down-risk in the shipping market. The COVID-19 pandemic occurred not from economic factors but from an ecological factor by the pandemic is different from the past economic crisis. It is necessary to analyze from a different point of view than the past economic crisis. This study has meaningful to analyze the causality and explanatory power of Congestion factor by pandemic.

• International Area Studies Review
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• v.13 no.3
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• pp.759-780
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• 2009

The purpose of this paper is to analyse the effect of Korean FDI(1990-2008) in China by industries on exports and imports between two countries. We use time series regression, Vector Error Correction Model and Impulse Response Function as methodologies. Our findings through empirical tests are as follows. First Korean FDI in China increases Korean exports with China but shows a tendency to decrease due to the local content of China. Second Korean FDI in China increases Korean imports in SITC 8 with China. Finally Korean trade surplus caused by Korean FDI in China shrinks due to the decreasing of exports and increasing of imports in Korea. Korean FDI in China should be oriented host country's market oriented rather than production efficiency oriented because of unfriendly foreign investment environments in China.

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.144-153
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• 2024

Recent research is increasingly focused on utilizing seismic waves for structure health monitoring (SHM). Specifically, seismic interferometry, a technique applied in geophysical surveys using ambient noise, is widely applied in SHM. This method involves analyzing the response of buildings to propagating seismic waves. This enables the estimation of changes in structural stiffness and the evaluation of the location and presence of damage. Analysis of seismic interferometry applied to SHM, along with case studies, indicates its highly effective application for assessing structural stability and monitoring building conditions. Seismic interferometry is thus recognized as an efficient approach for evaluating building integrity and damage detection in SHM and monitoring applications.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.69-74
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• 2011

In this study, it was prepared for nanofiber with high impact polystyrene(HIPS). HIPS is able to crosslinking after electrospinning with crosslinking agent and it could overcome brittle characteristics of polystyrene(PS). After thermal crosslinking, HIPS nanofiber was sulfonated by sulfuric acid. It was investigated FT-IR, XPS, water uptake, ion exchange capacity(IEC), SEM, and contact angle. According to the result of FT-IR and XPS, it was increased due to introduce the hydrophilic group($SO_3H$) in the HIPS nanofiber. The highest water uptake and IEC were 75.6%, 2.67 meq/ g at 120 min sulfonation time with 7.5 wt% DVB.

• KDI Journal of Economic Policy
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• v.26 no.2
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• pp.281-314
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• 2004

This paper theoretically formulated and empirically explored the relationship between exchange rate pass-through (ERPT) for (average) market price and an individual country's price, using steel products data in the US market, with special reference to two major steel exporting countries, Korea and Japan. It was found that the direction of market ERPT can be different from that of individual ERPT that each exporter experiences, due to strategic interactions among producers and different parameters. Vector error correction (VEC) models and impulse response analysis were used with the statistical inference based on the bootstrap-after- bootstrap of Kilian (1998) for short-run, and the fully modified estimation of Phillips and Hansen (1990) was used for long-run. Empirical results indicate that market ERPT in the US market due to changes in Korea-US exchange rates is different from those due to changes in Japan-US exchange rates. The framework developed in this study indicates that this phenomenon is attributed to either (i) the two countries have individual ERPTs of different magnitudes and directions for the products in the US market, or (ii) the pricing strategies of the other exporters' (to the US steel market) respond differently depending on whether the price of the product from Korea changes or that from Japan does. As each exporter's ERPT can be significantly different, and market response to each country's ERPT can be also different, this study concludes that it is crucial for an exporter to understand how competitors in the market respond to changes in its price, as well as to understand how its price changes when the relevant exchange rate fluctuates.

• The Korean Journal of Financial Studies
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• v.11 no.1
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• pp.101-132
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• 2005

증권시장 유동성 문제에 대해서는 학계뿐만 아니라, 투자자, 감독기관 및 시장관계자들의 관심도 크다. 최근의 금융 위기는 금융시장의 유동성이 급격히 감소할 경우 경제적으로 막대한 비용을 치르게 될 수 있음을 일깨워주고 있다. 국내에서도 증권시장의 유동성에 관한 연구는 발표되고 있으나 외국인 투자 행태가 증권시장 유동성에 큰 영향을 미칠 것임을 널리 인식하고 있음에도 불구하고 외국인 투자자와 우리나라 증권시장의 유동성에 어떠한 영향을 미치는지에 대한 체계적인 연구는 드문 실정이다. 따라서 본 연구에서는 유동성 개념에 내포된 시장의 깊이(depth), 시장의 폭(breadth), 가격탄력성(resiliency) 등을 반영하는 다양한 유동성 지표를 설정하고 Panel-VAR 모형에 근거한 충격반응함수를 이용하여 외국인투자행태가 이들 지표에 미치는 영향의 동학적 특성을 분석하였다. 실증분석 결과에 의하면 외국인투자 증가는 주식시장 유동성에 영향을 미치고 있음을 외국인 투자 비중이 높은 주식들 그룹과 이와 유사한 특성을 가진 주식들 그룹의 비교를 통해서 확인할 수 있었다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.133-140
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• 2018

In this paper we discover the generation principle of a sequence when the characteristic polynomial of the sequence is a power of a primitive polynomial. With the generation principle, we can rearrange a sequence. Also we get the linear complexity and the required term of the sequence efficiently.

• Journal of Korea Port Economic Association
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• v.28 no.3
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• pp.111-125
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• 2012

This study investigates the behavioral characteristic difference of the container volumes of three ports-Gwangyang, Incheon, and Pyeongtaek-Dangjin. All series span the period January 2003 to December 2011. I first test whether the series are stationary or not. I can reject the null hypothesis of a unit root in each of the level variables and of a unit root for the residuals from the cointegration at the 5 percent significance level. I hitherto make use of error-correction model and find that Gwangyang port is the slowest in adjusting the short-run disequilibrium, whereas the adjustment speed of Incheon is much faster than that of Gwangyang. The impulse response functions indicate that container volumes increase only a little to the negative shocks in exchange rate, while they respond positively to the shocks in the business activity in a great magnitude and decay very slowly to its pre-shock level. meaning that the shocks last very long. The accumulative response to the exchange rate increase of 20 won per dollar and the 5 point industrial production increase is the smallest in Gwangyang, no more than a half of that of two ports. The intervention-ARIMA models also forecast that Gwangyang port will have much lower growth rate than Incheon and Pyeongtaek-Dangjin port in trading volumes.

• The Korean Journal of Financial Management
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• v.24 no.4
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• pp.107-134
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• 2007

This paper tests the relationship among returns, volatilities, contracts and open interests of KOSPI 200 futures markets with the various dynamic models such as granger-causality, impulse response, variance decomposition and ARMA(1, 1)-GJR-GARCH(1, 1)-M. The sample period is from July 7, 1998 to December 29, 2005. The main empirical results are as follows; First, both contract change and open interest change of KOSPI 200 futures market tend to lead the returns of that according to the results of granger-causality, impulse response and variance decomposition with VAR. These results are likely to support the KOSPI 200 futures market seems to be inefficient with rejecting the hypothesis 1. Second, we also find that the returns and volatilities of the KOSPI 200 futures market are effected by both contract change and open interest change of that due to the results of ARMA(1,1)-GJR-GARCH(1,1)-M. These results also reject the hypothesis 1 and 2 suggesting the evidences of inefficiency of the KOSPI 200 futures market. Third, the study shows the asymmetric information effects among the variables. In addition, we can find the feedback relationship between the contract change and open interest change of KOSPI 200 futures market.

• Information Systems Review
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• v.16 no.2
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• pp.77-95
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• 2014

From the success of TDX and CDMA to today's social media boom, Korea's ICT has achieved an amazing growth for the last couple of decades. However, in spite of ICT's role as an engine of growth in Korea, there have been concerns that ICT growth would negatively affect national employment due to the labor substitution effect. While some scholars insist that ICT would positively affect employment because it will enlarge the size of industry itself, many people blame ICT as a main culprit of rising unemployment rates. In this study, we try to empirically find the true effect of ICT growth on employment in Korea. We use the data of ICT productions, ICT investments, and various industries employments from 1995 to 2011. The methodologies we adopted for this study is Granger causality tests and impulse response functions based on vector autoregression (VAR) model. We find that ICT has negative impact on service industries, while it has positive impact on manufacturing industries. Meanwhile, ICT has no statistically significant impact on ICT industry itself. Since the impacts of ICT on employment are mixed, we can argue that ICT should not be blamed for the main cause of low employment. We suggest a direction of future policies to utilize ICT for vitalizing employments in Korea.