• 기술혁신학회지
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• 제11권2호
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• pp.145-170
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• 2008

한국이동통신 산업의 2G에서 3G로 진화하는 기술 패러다임과 더불어 발생한 경쟁 양상은 네트워크 기반 산업에서의 혁신과 경쟁 전략에 대한 시사점을 제시해 준다. 사례 분석 결과 한국이동통신 산업은 지배적 사업자와 후발 사업자가 확연히 구분된 가운데 수확체증 법칙으로 인한 지속적인 시장지배자가 존재하는 형태를 보여주고 있고, 이러한 배경에는 시장의 경쟁적 지위에 따라 네트워크 특징과 구조가 반영된 차별적인 혁신과 경쟁 전략이 내재되어 있었다. 본 연구를 통해 전체 네트워크가 발생된 이동통신 산업 특성으로 인하여 후발사업자가 가져오는 와해성 혁신은 지배적 사업자의 점진적 혁신에 의해 실패하고 승자독식 체제가 지속되는 현상을 고찰할 수 있었다. 본 연구는 실증적으로 분석이 어려운 복잡계와 네트워크 효과에 관한 연구 주제에 대한 사례분석을 바탕으로 네트워크 특징과 구조를 적용한 수식(Numerical) 모형을 이용하여 시뮬레이션분석 기법을 이용한 차후 연구에 대한 이론적 기반을 확립하는데 의의가 있다.

• Asia pacific journal of information systems
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• 제24권2호
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• pp.233-253
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• 2014

Can the stock market really be predicted? Stock market prediction has attracted much attention from many fields including business, economics, statistics, and mathematics. Early research on stock market prediction was based on random walk theory (RWT) and the efficient market hypothesis (EMH). According to the EMH, stock market are largely driven by new information rather than present and past prices. Since it is unpredictable, stock market will follow a random walk. Even though these theories, Schumaker [2010] asserted that people keep trying to predict the stock market by using artificial intelligence, statistical estimates, and mathematical models. Mathematical approaches include Percolation Methods, Log-Periodic Oscillations and Wavelet Transforms to model future prices. Examples of artificial intelligence approaches that deals with optimization and machine learning are Genetic Algorithms, Support Vector Machines (SVM) and Neural Networks. Statistical approaches typically predicts the future by using past stock market data. Recently, financial engineers have started to predict the stock prices movement pattern by using the SNS data. SNS is the place where peoples opinions and ideas are freely flow and affect others' beliefs on certain things. Through word-of-mouth in SNS, people share product usage experiences, subjective feelings, and commonly accompanying sentiment or mood with others. An increasing number of empirical analyses of sentiment and mood are based on textual collections of public user generated data on the web. The Opinion mining is one domain of the data mining fields extracting public opinions exposed in SNS by utilizing data mining. There have been many studies on the issues of opinion mining from Web sources such as product reviews, forum posts and blogs. In relation to this literatures, we are trying to understand the effects of SNS exposures of firms on stock prices in Korea. Similarly to Bollen et al. [2011], we empirically analyze the impact of SNS exposures on stock return rates. We use Social Metrics by Daum Soft, an SNS big data analysis company in Korea. Social Metrics provides trends and public opinions in Twitter and blogs by using natural language process and analysis tools. It collects the sentences circulated in the Twitter in real time, and breaks down these sentences into the word units and then extracts keywords. In this study, we classify firms' exposures in SNS into two groups: positive and negative. To test the correlation and causation relationship between SNS exposures and stock price returns, we first collect 252 firms' stock prices and KRX100 index in the Korea Stock Exchange (KRX) from May 25, 2012 to September 1, 2012. We also gather the public attitudes (positive, negative) about these firms from Social Metrics over the same period of time. We conduct regression analysis between stock prices and the number of SNS exposures. Having checked the correlation between the two variables, we perform Granger causality test to see the causation direction between the two variables. The research result is that the number of total SNS exposures is positively related with stock market returns. The number of positive mentions of has also positive relationship with stock market returns. Contrarily, the number of negative mentions has negative relationship with stock market returns, but this relationship is statistically not significant. This means that the impact of positive mentions is statistically bigger than the impact of negative mentions. We also investigate whether the impacts are moderated by industry type and firm's size. We find that the SNS exposures impacts are bigger for IT firms than for non-IT firms, and bigger for small sized firms than for large sized firms. The results of Granger causality test shows change of stock price return is caused by SNS exposures, while the causation of the other way round is not significant. Therefore the correlation relationship between SNS exposures and stock prices has uni-direction causality. The more a firm is exposed in SNS, the more is the stock price likely to increase, while stock price changes may not cause more SNS mentions.

• East Asian Economic Review
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• 제23권4호
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• pp.353-379
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• 2019

This paper aims to determine factors causing the stagnation of Korean firms' fixed investment after the global financial crisis, using panel data for the period of 1999-2016. Fixed investment remained sensitive to cash flow and Tobin's q although their effects decreased after the global financial crisis. A decreasing trend of cash flow and an increase in Tobin's q since the early 2000's imply that the worsening cash flow was a major factor behind the sluggish investment after the crisis. Meanwhile, debt-equity ratio remained significant for non-chaebol affiliated firms, reflecting disparity in access to external financing. Volatility of stock returns also became insignificant after the crisis, casting doubt on the argument that uncertainty was a major factor contributing to the decline of fixed investment. Analysis of financial investment confirmed the significant effect of cash flow, larger than that on financial investment than on fixed investment. In particular, debt repayment and other financial investment, except share repurchase, were sensitive to cash flow. However, the substitution of fixed investment by financial investment is a consequence, rather than a cause of declining fixed investment.

• 자원ㆍ환경경제연구
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• 제21권3호
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• pp.627-681
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• 2012

본 논문은 독점적 경쟁과 내생적 성장의 모형으로 시작하여 생산과정에 투입되는 생산요소로서 오염을 추가했다. 그리고 환경의 질이 생산에 사용되는 재생가능한 자원인 것으로 채택했다. 본 논문은 생산요소로서 청정 활동의 분화에 기인하는 수확체증이 환경의 질을 해치지 않고 지속가능한 성장을 이끄는 데 도움을 줄 수 있다는 것을 보였다. 또한 오염과 독점적 경쟁으로부터 발생되는 두 가지 왜곡들을 교정할 수 있는 서로 다른 여러 가지 정책조합(조세 +보조금)을 비교하고 평가했다. 끝으로 본 논문은 최종재 생산에 있어 환경의 생산성이 충분치 않을 경우에 청정재의 수는 더 많은 환경적 우려와 함께 증가하는 경향이 있다는 것을 찾아냈다.

• 한국유기농업학회지
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• 제22권1호
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• pp.1-23
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• 2014

The purpose of this paper was to measure technical efficiencies and scale efficiencies of Korean seed industry by DEA method, and to identify the factors affecting the efficiencies by Tobit regression model. Survey data of 50 seed companies nationwide were applied for the analysis. The average score of overall technical efficiency for the surveyed companies in 2012 was 0.44, which is decomposed into pure technical efficiency 0.68 and scale efficiency 0.63. A majority of the seed companies exhibited at least one form of inefficiency except a few companies in optimal scale. It was also shown the most companies were operating in the stage of increasing returns to scale, which implies Korean seed companies are mainly in smaller scale than optimal. Additional results suggest that the Center for Private Seed Companies, which will be established at Gimje in 2015, plays an important role to make domestic seed companies improve their scale efficiency as well as pure technical efficiency by way of enlarging their size and co-using the high technology in the Center.

• 대한교통학회지
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• 제20권4호
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• pp.95-107
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• 2002

혼잡세나 한계비용요금정책은 교통시설의 이용에 혼잡이 있거나 서비스 제공에 규모의 경제가 존재하는 경우 강력히 추천되는 정책도구이다. 그러나 본 논문에서는 그와 같은 시각은 당해 시설 서비스 시장만 고려할 때만 타당할 뿐 다른 시장과의 상호작용을 염두에 둔 일반균형적인 관점에서는 일반적으로 성립되지 않음을 보인다. 또한 각 정책에 대해 혼잡세나 한계비용요금정책이 실패로 돌아가는 예를 구체적으로 보이고 그에 대한 정책적 대안이 제시된다. 이 과정에서 이용량 제한이나 평균비용 요금정책 등이 놀랍게도 전통적 수단보다 우수한 정책으로 등장한다. 그러나, 이 결과는 특수한 상황에서만 성립하는 것으로 이와 관련된 연구과제들이 결론적으로 제시된다.

• Asian-Australasian Journal of Animal Sciences
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• 제12권2호
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• pp.271-281
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• 1999

The cost of production of high quality pork is compensated by high returns, but constraints by the market are increasing. A few opportunities to maintain and improve pork quality by dietary means are presented. The healthy value of pork is a prerequisite. A careful control of suppliers and preservation of feeds are essential to protect pork against presence of contaminants from the feed. The feeding level and some dietary components modify the partition of the dietary energy into different pig tissues and chemical components of pork, affecting the hygienic and nutritional value, tenderness and taste. It is difficult to transfer a nutrient from the diet to pork, if the requirements. for growth are satisfied. Fatty acids and Vitamin E are the most studied exceptions. There is some evidence that iron and selenium contents can be affected too. Varying the content of a nutrient frequently changes sensorial and technological properties of pork. The addition of oils improves the acidic profile of depot fats, but the effect on phospholipid composition is not well studied and negative effects on oxidability and consistency of meat products are observed. Vitamin E can improve many healthy and sensorial characteristics, but its effect is clearer when the meat is stressed or manipulated.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제13권2호
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• pp.91-99
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• 2013

An autonomous unmanned underwater vehicle is a type of marine self-propelled robot that executes some specific mission and returns to base on completion of the task. In order to successfully execute the requested operations, the vehicle must be guided by an effective navigation algorithm that enables it to avoid obstacles and follow the best path. Architectures and principles for intelligent dynamic systems are being developed, not only in the underwater arena but also in related areas where the work does not fully justify the name. The problem of increasing the capacity of systems management is highly relevant based on the development of new methods for dynamic analysis, pattern recognition, artificial intelligence, and adaptation. Among the large variety of navigation methods that presently exist, the dynamic window approach is worth noting. It was originally presented by Fox et al. and has been implemented in indoor office robots. In this paper, the dynamic window approach is applied to the marine world by developing and extending it to manipulate vehicles in 3D marine environments. This algorithm is provided to enable efficient avoidance of obstacles and attainment of targets. Experiments conducted using the algorithm in MATLAB indicate that it is an effective obstacle avoidance approach for marine vehicles.

• 한국생활과학회지
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• 제20권6호
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• pp.1121-1133
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• 2011

Fair trade has received increasing attention from ethical consumers in the North Trans-Atlantic world. It is a movement establishing alternative trading organizations to ensure minimal returns, safe working conditions, and to provide continuity in the trading relationship for disadvantaged producers, especially women and indigenous people in the South. Despite of the growing fair trade movement in the U.S. and Europe, it is still in the introductory stage in Korea. Although fair trade has gained some attention because of the efforts of activists, most Korean consumers are still unaware of it. This paper is divided into four sections including an introduction and conclusions. In section two, I analysed sales of the fairly traded products and the websites of the fairly traded products sellers. In section three, I proposed two effective recommendations for the better marketing and promotion strategies of fairly traded products. One proposal is for providing consumer information, like fair trade certificates, consumer campaigns, and consumer information of the fair trade sellers' websites analyses. The other is for establishing the infrastructure to promote the consumption of fairly traded products such as consumer education, corporate social responsibility, social enterprise, fair trade town and school, and networking. This study is relavant to academics, non-profit fair trade organizations, manufacturers, retailers and governments.

• 산업경영시스템학회지
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• 제37권4호
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• pp.202-211
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• 2014

Pairs trading is a type of arbitrage investment strategy that buys an underpriced security and simultaneously sells an overpriced security. Since the 1980s, investors have recognized pairs trading as a promising arbitrage strategy that pursues absolute returns rather than relative profits. Thus, individual and institutional traders, as well as hedge fund traders in the financial markets, have an interest in developing a pairs trading strategy. This study proposes pairs trading rules (PTRs) created from a price ratio between securities (i.e., stock index futures) using rough set analysis. The price ratio involves calculating the closing price of one security and dividing it by the closing price of another security and generating Buy or Sell signals according to whether the ratio is increasing or decreasing. In this empirical study, we generate PTRs through rough set analysis applied to various technical indicators derived from the price ratio between KOSPI 200 and S&P 500 index futures. The proposed trading rules for pairs trading indicate high profits in the futures market.