• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.103-110
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• 2022

This paper deals with portfolio optimization problem that you could lower the total risk of an investment portfolio by adding risky assets to the mix than the minimum risk of single asset. Popular Markowitz's mean-variance(MV) model construct the portfolio with the point in the efficient frontier using principle of domination where the variance is minimized for a given mean return. While this paper suggest the portfolio with minimum risk asset with non-positive(negative and uncorrelated) correlation assets to it. As a result of experiments, the proposed method shows lower risk(standard deviation) than MV.

• Asia-Pacific Journal of Business
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• v.13 no.2
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• pp.123-138
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• 2022

Purpose - This study compares the performances of dynamic asset allocation strategies using Korean stocks and U.S. dollar, which have been negatively correlated for a long time, to examine the diversification effects in the portfolios of them. Design/methodology/approach - In the current study, we use KOSPI200 index, as a proxy of the aggregated portfolio of Korean stocks, and USDKRW foreign exchange rate to implement various portfolio management strategies. We consider the equally-weighted, risk-parity, minimum variance, most diversified, and growth optimal portfolios for comparison. Findings - We first find the enhancement of risk adjusted returns due to risk reduction rather than return increasement for all the portfolios of consideration. Second, the enhancement is more pronounced for the trading strategies using correlations as well as volatilities compared to those using volatilities only. Third, the diversification effect has become stronger after the global financial crisis in 2008. Lastly, we find that the performance of the growth optimal portfolio can be improved by utilizing the well-known momentum phenomenon in stock markets to select the length of the sample period to estimate the expected return. Research implications or Originality - This study shows the potential benefits of adding the U.S. dollar to the portfolios of Korean stocks. The current study is the first to investigate the portfolio of Korean stocks and U.S. dollar from investment perspective.

• The Korean Journal of Applied Statistics
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• v.29 no.7
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• pp.1201-1212
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• 2016

Value at Risk (VaR) for market risk management is a favorite method used by financial companies; however, there are some problems that cannot be explained for the amount of loss when a specific investment fails. Conditional Tail Expectation (CTE) is an alternative risk measure defined as the conditional expectation exceeded VaR. Multivariate loss rates are transformed into a univariate distribution in real financial markets in order to obtain CTE for some portfolio as well as to estimate CTE. We propose multivariate CTEs using multivariate quantile vectors. A relationship among multivariate CTEs is also derived by extending univariate CTEs. Multivariate CTEs are obtained from bivariate and trivariate normal distributions; in addition, relationships among multivariate CTEs are also explored. We then discuss the extensibility to high dimension as well as illustrate some examples. Multivariate CTEs (using variance-covariance matrix and multivariate quantile vector) are found to have smaller values than CTEs transformed to univariate. Therefore, it can be concluded that the proposed multivariate CTEs provides smaller estimates that represent less risk than others and that a drastic investment using this CTE is also possible when a diversified investment strategy includes many companies in a portfolio.

• Journal of Korea Technology Innovation Society
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• v.21 no.1
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• pp.33-63
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• 2018

The purpose of this study is to identify trends and to analyze knowledge structure and knowledge flow of studies on science and technology policy adopting the keyword network analysis. For analysis, we established a data set of published papers in the Journal of Korea Technology Innovation Society and Journal of Technology Innovation from 1993 to 2016. As a result of analysis, a great part of existing researches have been carried out in Seoul and Daejeon area, universities and public research institute. So it should be carried out in diversified form rather than being concentrated on specific regions or research performing subjects in the future. By research scope, more than 70% of research were carried out in 'R&D management' and 'technology innovation'. In the future, more research must be carried out in 'public process of science and technology' and 'public management of science and technology'. On the other hand, we performed the keyword network analysis to identify the knowledge structure of studies on science and technology policy. As a result of analysis, it was clustered into 'public process of science and technology', 'public management of science and technology', 'R&D management' and 'technology innovation', So It has not been different from research scope proposed by Yi, Kim and Oh(2016). And also, in earlier stage, research topics were general such as researchers and R&D investment. But as time goes by, topics were more diversified and subdivided. Therefore, in future, the research scope of studies on science and technology policy should be further expanded in terms of 'public process of science and technology', 'public management of science and technology', 'R&D management' and 'technology innovation', and systematic knowledge structure should be formed.

• Journal of the Korean Regional Science Association
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• v.15 no.2
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• pp.131-153
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• 1999

Since 1980's there have been two trends that obviously developed in the would -- economics globalization and urban internationalization. China, with is reform and opening-up policy and rapid economic growth, keeps pace with these two trends. The term "International City" has no putative standard or definition. If we make an analogue of urban functional hierarchy in the world with a pyramid, the International Citiesa are the few elites on its top. The highest level international cities can be called "World City" or "Global City". In today's new international division of labor, they are diversified leading cities with control capacity on a world scale, like New York, London, and Tokyo. The secondary international cities are either diversified cities with influence and regulative functions on multinational scale or specialized cities on politics, economics, culture, or other aspects with worldwide impact. Judged by different criteria, there is no city that is qualified as International City with the exception of Hong Kong, which was returned to the P.R. of China in 1997. Nevertheless, Some favorable conditions for the development of the international city still exist in China. This country is already the sixth largest economic entity in the world, and the second largest economic entity in the world, and the second largest one if GNP estimated by ppp. Furthermore its import and export value make up for 40% of its GNP, indicating that China is repidly merging into global economy. In this 1, 2 billion-population country, the difference of economic levels between urban and rural, coastal and inland regions is so big that a few metropolises in the coastal region have the possibilities and potentials to develop into international cities regardless of rather low GNP per capita of the whole country. This article will focus on analysis from several perspectives, such as the proportion of foreign trade values in GDP, the proportion of imports and exports by foreign funded enterprises in total foreign trade value; distribution of the 500 largest foreign-funded enterprises; distribution of the 500 enterprises with largest import and export values; distrigbution of foreign computer and telecom companies with offices in China; the number of outward flights per week and the international tourists; the value of foreign capital used in cities and so on. From this analysis, it is predicted that Chinese international cities will surely emergy from the eastern coastal regions and they must be the core cities of metropolitan interlocking regions that have been formed or in the process of forming. Those international cities will arise from south to north in turn : Hong Kong-Guangzhu, Shanghai, Beijing-Tianjin, and perhaps the last one is Dalian-Shenyang. The other side of this issue is that there is a long way for the coming international cities in China except Hong Kong. At least China and these core cities must continually devote to (1) improve the regional composition of foreign capital sources. (2) improve the composition of export commodities. (3) improve the investment environment (including hard and soft environment) to attract more transnational corporations to settle. (4) deepen the reform of state-owned enterprises and establish Chinese own transnational corporations to enter the world market.ons to enter the world market.

• Journal of the Economic Geographical Society of Korea
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• v.22 no.2
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• pp.214-235
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• 2019

This study adopts the concept of social innovation cluster in which social economy organizations as one of the emerging axes of economic systems operate in collaboration with government agencies, investment institutions, intermediate supporting organizations and non-profit organizations, and investigates how the clusters of this kind grow in the context of the Korean socio-economic situation for the cases of Seongdong-gu and Eunpyeong-gu in Seoul, Korea. For this purpose, it has identified the actors of the clusters and their internal relations, and analyzed the process of cluster formation. A social network analysis of the partnerships between the actors has shown that Seongdong-gu has more diversified types of the network participation of universities, global networks and investment institutions than Eunpyeong-gu. It is interpreted that this pattern has resulted from the domination of private organizations in the former area, which is also confirmed by in-depth interviews with persons involved in the clusters. Although the facets of social innovation clusters are manifested in both areas, even in their initial stage, such factors as linkages between industrial actors and convergence with other clusters, which appear in the maturing stage of cluster formation, has yet to be found. It is suggested that the sustainable growth of social innovation clusters should be accompanied by information sharing and cooperation between the two areas on the future orientation of development.

• Korean Journal of Organic Agriculture
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• v.6 no.2
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• pp.127-140
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• 1998

Organic farming excludes any use of the herbicide. The present paper reviews what can be done for effective weed control with existing weed control technology by farmers crop-ping paddy rice, field crops, vegetables, and fruit trees. If condition of the crop-land-al-lows diversified rotational use of the paddy land as paddy and upland field would minimize weed problem. Practising this is limited in acreage due to extremely limited governmental investment to the land for the purpose. Secondly, rotation of crops in the upland field breaking life cycles of various weeds adapted to each crop should reduce the weed problem. This is also limited as only a few crops are making the farmer profitable. In addition climate and tolerance of crops to high and low temperature. Monsoon rains and poor drainage restrict the freedom of choice. For any crop land year-round multiple cropping in denser planting shall lessen the weed problem, this multiple cropping practiced by 1960s has been abandoned due to laborshortage and increased production cost. Deep flooding the rice is impractical at present in Korean. Mulching crop with transparent, black , or combinated polyethylene sheet, hs been in-creasingly used. Progresses in development and use of mulch with allelopathic crop residues. inexpensive paper mulch, allelopathic crop residues, inexpensive paper mulch, allelopathic crop cultivar development, recently developed ex-perimental weeding machinaries, flamers, microbial herbicides, biological control organisms, soil sterilization techniques have been critically reviewed for their adoption into existing in-tegrated weeding system. Unfortunately, information on cost-benifit, and labor-benefit, for the various methods above mentioned are lacking. Urgent need for the research on rational weeding in organic farming, and herbicide low-input farming is emphasized.

• The Korean Journal of Applied Statistics
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• v.34 no.1
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• pp.39-56
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• 2021

Many researches have been done on portfolio optimization since Markowitz (1952) published a diversified investment model. Markowitz's mean-variance portfolio optimization problem is established under the assumption that the distribution of returns follows a normal distribution. However, in real life, the distribution of returns does not follow a normal distribution, and variance is not a robust statistic as it is heavily influenced by outliers. To overcome these potential issues, mean-shortfall portfolio model was proposed that utilized downside risk, shortfall, as a risk index. In this paper, we propose a perturbation method that uses the shortfall as a risk index of the portfolio. The proposed portfolio utilizes an adaptive Lasso to obtain a sparse and stable asset selection because it can reduce management and transaction costs. The proposed optimization is easily applicable as it can be computed using an efficient linear programming. In our real data analysis, we show the validity of the proposed perturbation method.

• East Asian Economic Review
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• v.26 no.1
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• pp.49-91
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• 2022

Recent years have witnessed renewed interest in Africa and public diplomacy has emerged as the vital tool being used to cultivate these relations. China has been leading in pursuing stronger economic partnership with Africa while middle powers such as Korea are also intensifying engagement with the continent. While previous studies have analyzed the implications of China's activities in Africa on advanced powers, none has examined them from the paradigm of middle powers. This study fills this gap by assessing China's activities in Africa, their economic engagement and implications for Korea's interest in Africa. The analysis is qualitative based on secondary data from various sources and literature. The study shows that China's public diplomacy strategy involves a high degree of innovation and has evolved to encompass new tools and audiences. China has institutionalized a cooperative model that permeates many aspects of governance institutions in Africa, enabling it to strengthen their relations. This could also be helping China to adjust faster leadership transitions in Africa. Whereas the US is still the most influential country in Africa, China is influential in economic policies and has outstripped the US in infrastructure diplomacy. This could be because African policy makers align more with China's economic model than the US' mainstream economics. Chinese aid to Africa has been diversified to social sectors that are more responsive to the needs of Africa. Trade and investment relations between China and Africa have deepened, but so does trade imbalance since 2010. China mainly imports natural resources and raw materials from Africa. But this product portfolio is not different from Korea and the US. China's energetic insertion in Africa using various strategies has significant implications for countries with ambitions in Africa. Korea can achieve its ambitions in Africa by focusing resources in areas it can leverage its core strengths-such as education and vocational training, environmental policy and development cooperation.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.5
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• pp.1-12
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• 2017

The purpose of this study is to investigate the trends of the start-up research in Korea. To accomplish this, meta-analysis was carried out using text mining methodology by dividing the entrepreneur-related master's and doctoral theses registered in RISS into the first term of entrepreneurship research by 2009 and the second term of entrepreneurship research from 2010. As a result of this study, it can be seen from the three different analysis that the entrepreneurship education and government policy and support are the subject of continuous research topics in the whole period and that the researches on small business start-ups have been studied continuously and conducted more in the second half. In addition, empirical analysis is strengthened in the latter stage of entrepreneurial research. The TF-IDF analysis reveals that many researches on veterans have been carried out in the field of entrepreneurship research, and in the latter period, it was found that many studies related to the elderly were conducted with cultural contents and aging society. In addition, research on brand-related research has been carried out throughout the entire period, and research on venture-related research, characteristics of entrepreneurs, entrepreneurship motivation and start-up strategy have been conducted a lot and female entrepreneurship was also studied. In the latter period, we have emphasized entrepreneurial achievements and found that research on start-ups such as industry-academia cooperation, start-up investment, and social enterprise diversified. This study is meaningful to apply the method which is becoming a recent issue such as text mining and topic analysis to the meta-analysis related to start-up. Future research will need to be undertaken on a variety of more detailed topics related to entrepreneurship.