• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.3
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• pp.149-153
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• 2022

The degree distribution of the plant-pollinator network was identified by analyzing the data in the ecosystem and reproduced by a model of the growing bipartite mutualistic networks. The degree distribution of pollinator shows power law or stretched exponential distribution, while plant usually shows stretched exponential distribution. In the growth model, the plant and the pollinator are selected with probability P_p and P_A=1-P_p, respectively. The number of incoming links for the plant and the pollinator is l_p and l_A, respectively. The probability that the link of the plant selects the pollinator of the existing network given as $A_{k_i}=k^{{\lambda}_A}_i/{\sum}_i\;k^{{\lambda}_A}_i$, and the probability that the pollinator selects the plant is $P_{k_i}=k^{{\lambda}_p}_i/{\sum}_i\;k^{{\lambda}_p}_i$. When the nonlinear growth index is 𝛌_X=1 (X=A or P), the degree distribution follows a power law, and if 0≤𝛌_X<1, the degree distribution follows a stretched exponential distribution. The cumulative degree distributions of plants and pollinators of 14 empirical plant-pollinators included in Interaction Web Database were calculated. A set of parameters (P_A,P_P,l_A,l_P) that reproduces these cumulative degree distributions and a growth index 𝛌_X (X=A or P) were obtained. We found that animal takes very heterogenous connections, whereas plant takes a more flexible connection network.

• International Area Studies Review
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• v.13 no.1
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• pp.123-143
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• 2009

This paper investigates the determinants of total factor productivity(TFP) growth in Korean logistics industry such as market share, ownership structure, age of firm, firm size and debt ratio. Using financial data on individual firms in Korean logistics industry, we first estimate firm-level TFP growth rate and then, regress the estimated TFP growth rate on individual firms market power and structural characteristics. Our empirical results show that logistics firms market share is negatively correlated with their TFP growth rate. Also, we find that older or larger firms are more likely to have higher TFP growth rate.

• Journal of Korea Technology Innovation Society
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• v.16 no.4
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• pp.937-953
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• 2013

The theoretical discussion of generation process and development directions of economic fluctuations are actively discussed. This study describes the economic changes applied to empirical research on economic volatility in Korea under the economic theory of network theory [Acemoglu, et al. 2012, 2010]. For the three years in 2000, 2005, and 2010, the network analysis were applied to industry input-output tables. The research results show that the network economic structures in Korea is shifted from a high connectivity among sectors to a lower connectivity. Also, the impact of key industries and the mutual connectivity of input and out among industrial sectors are weaken. Implications for industry and technology policy are derived form the study results.

• KDI Journal of Economic Policy
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• v.36 no.4
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• pp.71-102
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• 2014

This paper examines the possibility of 'parallel reimportation', the reimportation of goods originally produced in the country and exported to another country by profit-pursuing arbitrageurs. The chance of parallel reimportation implies unusually high level of market power of domestic enterprises, and promoting parallel reimportation can be an effective welfare-enhancing, competition-generating policy for the situation. Motivated by the finding, this paper proposes a methodology to measure the welfare effects of parallel reimportation. Specifically, this paper makes use of a structural empirical model to estimate the demand and supply system of Korean automobile market for performing a counterfactual experiment to measure the welfare effects of the parallel reimportation. The results indicates that parallel reimportation can enhance social welfare considerably by increasing consumer surplus and government tax revenue altogether, though it reduces the producer surplus.

• Journal of the Korean Society of Costume
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• v.66 no.6
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• pp.122-134
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• 2016

With the advent of the new political regime of Jong Un Kim, North Korea is undergoing many changes, with its main motivation being economic growth. This study aims to identify the changes in clothing in North Korea under the new political climate. The research conducted a review on literature and empirical study. For literature review, books and papers from studies related to North Korea have been reviewed. For the empirical part, interviews with diverse class of North Korean refugees including Hanawon, videos on TV, 1,100 pictures and related articles from newspapers and Internet have been collected. Through this analysis, the study found that subtle changes in North Korean fashion started prior to the Jong Un Kim's regime, but has become full-blown since Kim's assumption of power. This proves that the country is not yet independent from its political situation. The results are as follows: First, the appearance of Ri Sol-ju has liberalized the fashion concept of North Korean women, and the popularity of her trademark style has actually contributed to a more amicable image for Kim. Second, the "Hallyu" style has spread to North Korea through various channels, and has started new trends. Third, the diversification of fashion styles has been greatly accelerated in accordance with the expansion of market, resulting from the economic revitalization policy. Last of all, Jong Un Kim's direct orders concerning fashion have resulted in some significant changes. The sophisticated uniforms of flight attendants and the development of luxury cosmetics being prime examples. As studies on this subject are extremely rare, this research is significant to identify the changes on the clothing culture under Jong Un Kim's regime, and to present an expanded view, as the two countries work towards an united Korea.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1140-1147
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• 2013

In this paper, The path loss model of Air Traffic Control(ATC) telecommunication radio channel has been studied at the Incheon International Airport(IIA) Cargo Terminal. We measured one frequency among VHF channel bands. The transmitting site was located at different locations with different heights. The transmitting site radiated the Continuous Wave(CW). The propagation measurement was taken using the moving vehicle equipped with receiver and antenna. The transmitting power, frequency and antenna height are the same as the current operating condition. The path loss exponent and intercept parameters were extracted by the basic path loss model and hata model. The path loss exponent at IIA Cargo terminal area were 3.67 and 3.39 respectively in first and second transmitting sites. The deviation of prediction error is 14.42 and 10.38. The new path loss equation at the IIA Cargo terminal area was also developed using the derived path loss parameters. The new path loss was compared with other models. This result will be helpful for the ATC site selection and service quality evaluation.

• Korean System Dynamics Review
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• v.13 no.3
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• pp.47-66
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• 2012

This paper aims at investigating and identifying the factor that has led the back and forth relationship between China and the United States since 1989. Previous studies on this subject addressed the issue by taking either of two approaches: one with the micro view that interprets the back and forth relationship in the context of the end of the Cold war, on other hand, with the macro view that interprets the fragile relationship in the context of the rise of China. However, neither of the approaches explains with sufficiency the question at hand. Hence for the inquiry, this article suggests a fresh view by exploring alternative method of using a cognitive map of each nation's leader, Jiangzemin and Bill Clinton. This article provides an empirical analysis through the Selected works of Jiangzemin and the speeches of Bill Clinton in 1998 for the first time in the field of Sino-US relationship studies in Korea. With the results of the cognitive map analysis, we can reach the following four points. Firstly, indicators of the forth relationship between China and the US are: i) the recognition by Bill Clinton on the importance of China's economic growth and; ii) the US's cooperation of science technology with China. Second, the conflict between China and the US results from the discordance of opinions on the matter of human rights and military power. Second, the conflict will inevitably arise on environmental issues around the globe including a global warming. Third, while China has yet to find a legitimate reason to agree upon these issues with the US, the US urges China of its cooperation. Lastly, Both China and the US attach great importance to the alliance with Japan. This implicates that relatively, issues involving Japan take more control in the China-US relationship, than those of Korea Peninsula.

• Journal of KIISE
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• v.41 no.12
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• pp.1050-1057
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• 2014

Electroencephalogram (EEG)-based brain-computer interfaces (BCI) can be used for a number of purposes in a variety of industries, such as to replace body parts like hands and feet or to improve user convenience. In this paper, we propose a method to decompose and extract motor imagery EEG signal using Empirical Mode Decomposition (EMD) and Fast Fourier Transforms (FFT). The EEG signal classification consists of the following three steps. First, during signal decomposition, the EMD is used to generate Intrinsic Mode Functions (IMFs) from the EEG signal. Then during feature extraction, the power spectral density (PSD) is used to identify the frequency band of the IMFs generated. The FFT is used to extract the features for motor imagery from an IMF that includes mu rhythm. Finally, during classification, the Support Vector Machine (SVM) is used to classify the features of the motor imagery EEG signal. 10-fold cross-validation was then used to estimate the generalization capability of the given classifier., and the results show that the proposed method has an accuracy of 84.50% which is higher than that of other methods.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.395-404
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• 2008

We explore the linkage between the long term variability of the Sun and earth's climate change by analysing periodicities of time series of solar proxies and global temperature anomalies. We apply the power spectral estimation method named as the periodgram to solar proxies and global temperature anomalies. We also decompose global temperature anomalies and reconstructed total solar irradiance into each local variability components by applying the EMD (Empirical Mode Decomposition) and MODWT MRA (Maximal Overlap Discrete Wavelet Multi Resolution Analysis). Powers for solar proxies at low frequencies are lower than those of high frequencies. On the other hand, powers for temperature anomalies show the other way. We fail to decompose components which having lager than 40 year variabilities from EMD, but both residuals are well decomposed respectively. We determine solar induced components from the time series of temperature anomalies and obtain 39% solar contribution on the recent global warming. We discuss the climate system can be approximated with the second order differential equation since the climate sensitivity can only determine the output amplitude of the signal.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.12
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• pp.55-67
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• 2010

The electrical properties of a back drilled via-hole (BDH) without the open-stub and the plated through via-hole (PTH) with the open-stub, which is called the conventional structure, in a high-count multi~layered (HCML) printed circuit board (PCB) were investigated for a high-speed digital system, and a selected inner layer to transmit a high-speed signal was farthest away from the side to mount the component. Within 10 GHz of the broadband frequency, a design of experiment (DOE) methodology was carried out with three cause factors of each via-hole structure, which were the distance between the via-holes, the dimensions of drilling pad and the anti-pad in the ground plane, and then the relation between cause and result factors which were the maximum return loss, the half-power frequency, and the minimum insertion loss was analyzed. Subsequently, the empirical formulae resulting in a macro model were extracted and compared with the experiment results. Even, out of the cause range, the calculated results obtained from the macro model can be also matched with the measured results within 5 % of the error.