• KDI Journal of Economic Policy
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• v.22 no.1_2
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• pp.363-417
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• 2000

우리 경제는 외환위기를 계기로 단기금융시장을 포함한 국내 자본시장이 전면 개방된 동시에 외환거래 역시 대폭 자유화됨에 따라 실물부문은 물론 금융부문에 있어서도 완전한 개방경제체제로 전환하였다. 이러한 전면적인 자본시장 개방은 국내외 자본시장의 통합을 촉진하는 동시에 환율, 금리, 물가 등 거시 금융변수간의 상충관계(trade-off)에 변화를 초래함으로써 거시경제정책 환경도 크게 변호시킬 것으로 기대된다. 본고에서는 국내외 금리 및 주가간의 동조화 현상에 초점을 맞추어 자본시장 개방에 따른 국내외 자본시장 통합 효과를 살펴본 후, 자본시장 개방이 환율변동패턴의 통계적 특성에 어떠한 영향을 미쳤는지를 분석하였다. 특히 외환위기를 계기로 국내 자본시장이 제도적으로 완전 개방된 점을 고려하여 위기 이전과 이후에 자본시장 통합도와 환율 변동패턴에 어떠한 변화가 발생하였는지를 실증분석하였다. 금리에 대한 실증분석 결과는 외환위기 이후 금리재정거래(金利裁定去來)(interest parity)가 국내금리변화에 미치는 영향이 크게 확대되고 있음을 나타내고 있다. 주가에 대한 실증분석의 경우에도 미국과 국내주가 간의 동조화 현상이 외환위기 이후 심화되고 있으며, 국내 주식시장이 효율적 시장가설(efficient market hypothesis)을 지지하는 방향으로 변화하고 있음을 나타내고 있다. 환율의 경우에도 외환위기 이후 환율변동패턴에 임의보행(random walk)적 특성이 보다 강화된 것으로 나타나고 있어 외환시장의 효율성이 제고되었음을 시사하고 있다.

• The Korean Journal of Applied Statistics
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• v.23 no.3
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• pp.443-456
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• 2010

This study is an empirical research of the stock markets to prove the synchronization phenomenon of the world economy. For this research I analyzed Korea's KOSPI, USA's DOW & NASDAQ reflecting stock markets in North America, Japan's NIKKEI in Asia, and Germany's DAX in Europe. Because the raw series are not stationary, they are to be transformed to returns series. The results of the study are follows: First of all, there are significant causalities between KOSPI's returns and those of other indices. Second, feedback effects are found between the market returns with several time lags. Third, there are 4 cointegrating equations which embody the relation of the five returns series. And forth, KOSPI reacts more sensitively to impacts from the foreign indices compared to the other indices do when they got impacts from each other except KOSPI. On conclusion, there exists a clear evidence for the synchronization phenomenon in returns of the stock indices, and we can expect Korea market may get similar changes depending on the economic changes of North America, Europe, or Asia. Therefore more closing researches should be conducted about the world economy synchronization in various fields as soon as possible.

• Electronics and Telecommunications Trends
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• v.22 no.6
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• pp.182-193
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• 2007

본 연구에서는 프랑스, 영국, 핀란드 등 유럽을 대표하는 몇몇 국가와 미국, 일본, 호주 등 주요국을 대상으로 $800{\sim}900MHz$ 대역의 이용현황 및 활용사례를 살펴보았다. 특히, 저대역 주파수에서 상업적 가치가 높은 이동통신용 주파수의 이용현황 및 전개방향을 중심으로 살펴보았다. 그 결과 전세계적으로 이동전화서비스의 성장 및 신규서비스의 도입으로 주파수 수요가 급증함에 따라 주파수 부족현상이 심화되고 있고, 이에 따라 효율적인 주파수 사용을 위해 국가별로 회수 재배치가 중요한 이슈로 부각되고 있음을 알 수 있었다. 본 연구에서는 동조화가 높은 저대역 주파수에 대한 해외 주요국의 이용동향을 살펴봄으로써 향후 부족한 전파자원에 대한 유용한 시사점을 도출하고자 하였다. IMT-2000 주파수의 동조화는 800MHz와 900MHz 대역을 중심으로 이루어지는데 해외의 저대역 주파수에 대한 이용선례는 향후 통신사업자들의 사업방향에 중요한 지표가 될 것으로 기대된다. 이러한 연구는 전파정책을 추진하는 당국과 사업자에게 정책결정을 하는 데 유용한 정보를 제공할 것이라 기대된다.

• Journal of Digital Convergence
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• v.19 no.2
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• pp.151-160
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• 2021

The purpose of this study is to classify online shopping malls into total transaction amount and transaction amount by product, and compare them to find synchronism. The data used in this study were collected from KOSIS for Food Services, Home Appliances·Electronics·Communication devices, Food & Beverages, House_Goods, Clothing, Computers & Peripheral Devices. The analysis period is a total of 44 monthly data from January 2017 to August 2020. In descriptive statistics, variability is relatively very stable in the case of food service, but is large in the case of clothing. In the correlation analysis, the total transaction amount shows a certain level of correlation with each product. In the analysis of the increase rate, Food Service increased by 1,039%, Home Appliances·Electronics·Communication devices increased by 325%, Food & Beverages increased by 296% and House Goods by 250%, but Clothing decreased slightly to 92.56%. In the Scatter Charts analysis, the distribution of Total transaction amount & House Goods, Total transaction amount & Home Appliances·Electronics·Communication devices is generally upward, showing a high level of synchronization. Due to Corona 19, we will have to continue our efforts to provide speed, stability, convenience and various services in preparation for the increase in transaction volume of online shopping malls.

• Convergence Security Journal
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• v.20 no.4
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• pp.217-225
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• 2020

In recent years, the "social distance" has drastically reduced overseas travelers. On the other hand, for personal safety and security, it is expected that interest and demand for CCTV, electric alarm and signaling devices, electric diagnostics and medical devices will increase significantly. The purpose of this paper is to find out the effect of airport transfer passengers and exports of CCTV, electrical diagnostics and medical devices, electrical alarms and signaling devices on exports to Korea, and the synchronism of each variable. To this end, this study used a total of 231 monthly data from January 2000 to April 2020 in the National Statistics Service. As a result of empirical analysis, CCTV and electrical diagnostics and medical devices showed relatively high synchronization with respect to exports to Korea. Electric alarms & signaling devices and transit passengers also showed a certain level of synchronization with exports, but were relatively weak.

• Journal of Digital Convergence
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• v.18 no.2
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• pp.197-204
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• 2020

The purpose of this paper is to find the direction by analyzing the synchronization phenomenon and the change rate of apartment charter rate in Korea, Seoul, Busan, Daegu, Gwangju and Daejeon. For this purpose, this study used a total of 239 monthly data from January 2000 to November 2019 in Kookmin Bank housing statistics. In the correlation analysis, Korea showed the highest relationship in order of Seoul, Busan, Incheon and Daegu. Seoul showed a low figure of 0.3 without any distinctive features from other cities. On the other hand, Busan, Daejeon and Daegu showed high correlations. As a result of the regression analysis, Korea and 5 major cities were all moving in the same direction with positive(+) values. And Busan and Seoul responded significantly to Korea. In the shock response, Korea is most shocked by the change in Seoul. Daegu is relatively shocked by Busan and Daejeon. Seoul's charter rate has declined most strongly in the last three years. Therefore, it is time to be careful not to incur losses due to gap investment. If we look at the relationship between the charter rate and the sale price in future studies, we can better understand the Korean apartment market.

• Journal of Navigation and Port Research
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• v.41 no.1
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• pp.1-8
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• 2017

The estimation of non-linear ship motion is one of the most important issues in recent studies of ship stability. In this paper, bispectral analysis and bicoherence analysis were introduced in order to analyze the non-linear ship motion. In addition to the previously observed non-linear pitching motion in following seas, this study observed the non-linear phase coupling of pitching motion in following & quartering seas, and starboard beam seas. By comparing phase coupling between each frequency quantitatively via the bicoherence analysis, it was confirmed that non-linear phase coupling was much stronger in frequency regions other than the peak frequencies of a power spectrum. Furthermore, it was found out that the results of bicoherence calculation were analagous to each other, although the different normalization methods were applied.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.1-8
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• 2006

A linear acoustic analysis is conducted to examine bituning of acoustic resonators for acoustic damping in a combustion chamber of liquid rocket engine. Bituned resonators are tuned to the two principal modes, the first tangential(1T) and the first radial(1R) modes. First, the acoustic-damping effect of monotuned resonators is investigated. The damping capacity is quantified by damping factor as a function of the number of the resonators monotuned to 1T or 1R mode. Next, the damping characteristics of the bituned resonators are investigated. From the numerical data, the number of resonators, to be tuned to 1T and 1R modes, respectively, can be selected properly. Furthermore, the concept of resonator bituning is applied to reduce the degradation of damping effect caused by the mode split and thereby, optimal bituning frequencies are found.

• Journal of Korean Society of Steel Construction
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• v.26 no.3
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• pp.177-189
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• 2014

When floor vibration problems occur in existing buildings, TMD (tuned mass damper) can be a viable alternative to resolving the problem. Only when TMD has been exactly tuned to the natural frequency of the floor, it can control the vibration as intended in design. However, TMD gets inefficient in the situation where the natural frequency changes as a result of the uncontrollable variation of the floor mass weight. This physical phenomenon is often called as TMD-off-tuning. This study proposes asymmetric TMD for enhancing the robustness of floor vibration control against uncertain natural frequencies. The proposed TMD features two asymmetric linear springs such that the floor vibrational energy can be dissipated through both the translational and rotational motion. An easy-to-use graphical optimization method was developed in this study. The asymmetric TMD proposed outperformed in vibration control by 28% compared to that of conventional TMD. The robustness of asymmetric TMD of this study was two times higher than that of conventional TMD.

• Management & Information Systems Review
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• v.35 no.3
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• pp.1-22
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• 2016

We analyzed the international comovements and structural changes in the quarterly real GDP by the Markov-switching vector autoregressive model (MS-VAR) from 1971(1) to 2016(1). The main results of this study were as follows. First, the business cycle phenomenon that occurs in the models or individual time series in real GDP has been grasped through the MS-VAR models. Unlike previous studies, this study showed the significant comovements, asymmetry and structural changes in the MS-VAR model using a real GDP across countries. Second, even if there was a partial difference, there were remarkable structural changes in the economy contraction regime(recession), such as 1988(2) ending the global oil shock crisis and 2007(3) starting the global financial crisis by the MS-VAR model. Third, large-scale structural changes were generated in the economic expansion and/or contraction regime simultaneously among countries. We found that the second world oil shocks that occurred after the first global oil shocks of 1973 and 1974 were the main reasons that caused the large-scale comovements of the international real GDP among countries. In addition, the spillover between Korea and 5 countries has been weak during the Asian currency crisis from 1997 to 1999, but there was strong transmission between Korea and 5 countries at the end of 2007 including the period of the global financial crisis. Fourth, it showed characteristics that simultaneous correlation appeared to be high due to the country-specific shocks generated for each country with the regime switching using real GDP since 1973. Thus, we confirmed that conclusions were consistent with a number of theoretical and empirical evidence available, and the macro-economic changes were mainly caused by the global shocks for the past 30 years. This study found that the global business cycles were due to large-scale asymmetric shocks in addition to the general changes, and then showed the main international comovements and/or structural changes through country-specific shocks.