• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.826-827
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• 2007

우리나라의 현행 전원믹스는 경제성의 측면에서 상당히 왜곡된 것으로 언급되고 있으며, 전력시장의 기저발전기에 대한 규제상한 가격은 이를 간접적으로 입증하는 근거라 할 수 있다. 균등화 발전원가를 이용하여 장기한계비용을 도출하고, 이를 부하지속곡선에 대입하여 산출한 경제적 전원믹스은 원자력 발전용량의 대폭적인 증가의 필요성을 보여준다. 이는 원전이 기저전원으로 경제성을 가지는 측면이 있지만 무엇보다도 우리나라의 높은 부하율(편평한 부하지속곡선)에 기인하고 있다. 이산화탄소 배출비용의 부과는 원전의 경제적 우위를 확장시키는 반면 전원다변화를 현격하게 축소시키는 결과를 가져와 정책목표간 조율이 필요함을 시사한다. 균등화 발전원가는 전력시장체제의 가격 및 수익에 대한 리스크를 효과적으로 반영하지 못하므로 포트폴리오 이론 및 실물옵션 이론 등을 활용한 경제성 평가방법론의 개발이 향후 과제로 제기된다.

• Vending industry
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• v.2 no.5 s.6
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• pp.43-49
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• 2002

올 들어 '대박의 꿈'복권시장의 폭발적인 확대와 더불어 복권자판기 시장을 많은 업체들의 우후죽순격 시장가세를 불러 일으켰다. 시류에 편승하는 기획상품으로서의 큰 파급력을 보이여 시장을 확대하던 복권자판기 시장은 그러나 그 영화를 오래 지속하지 못했다. 대다수 업체들이 판매만을 위한 판매 정책을 지향했고, 이에 따라 무리수 있게 필드에 설치된 복권자판기들이 낮은 수익성 등의 문제로 운영효율이 살지 않자 시장성은 급락직하하게 된 것이다. 애초부터 장기적인 유망시장으로 볼 수 없는 분야였기 때문에 업체들의 시장을 이끌고 가는 정책도 단기성 사업에 집착하는 한계를 보인 것이 복권자판기 시장 몰락을 불러일으킨 주요인이다. 불과 1년여도 못가는 단기시장으로서 이미 끝물에 도달한 듯한 복권자판기 시장을 통해 실수요 아이템이 아닌 무리하게 급조된 시장을 형성 발전시켜 가는 것이 얼마나 무모한지를 여실히 느낄 수 있다. 현시점에서 하강곡선을 긋는 복권자판기 시장 현실을 바라보는 기분은 그리 유쾌할 리가 없다. 하지만 산업계가 숙연히 지난 시장 과오를 반성하고 앞으로의 새로운 시장 재편을 준비해야 한다는 점에서 복권자판기 시장의 그 이유 있는 몰락을 심층 분석해 보는 일도 의미 있는 일일 게다.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.435-438
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• 2020

시장예측 문제를 해결하기 위하여 과거부터 꾸준한 연구가 진행되어왔다. 하지만 금융 시계열 데이터에는 분산이 일정하지 않으며 Non-stationarity 등 예측을 하는 것에 있어서 여러 가지 방해 요인이 존재한다. 또한 광범위한 데이터 변수는 기존에 사람이 직접 경험적으로 선택하는 것에 한계가 있기 때문에, 모델이 변수를 자동으로 추출할 수 있어야 한다. 본 논문에서는 여러 가지 금융 시계열 데이터의 문제를 고려하여 타임 스텝 정규화를 제안하며 자동 변수 추출을 위해 LSTM 형태의 오토 인코더 모델을 학습하였으며 LSTM 네트워크를 이용하여 시장 예측하는 모델을 제안한다. 해당 시스템은 실제 주식 거래나 시장 거래를 위하여 온라인 학습이 가능하며 긴 기간을 테스트 구간으로 실험한 결과 미래의 수익률을 예측하는 것에 있어서 우수한 성능을 보였다.

• Information Systems Review
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• v.10 no.2
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• pp.195-209
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• 2008

Customers' needs change every moment. Profitability of stores can't be increased anymore with an existing standardized chain store management. Accordingly, a personalized store management tool needs through prediction of customers' preference. In this study, we propose a recommending procedure using dynamic customers' preference by analyzing the transaction database. We utilize self-organizing map algorithm and association rule mining which are applied to cluster the chain stores and explore purchase sequence of customers. We demonstrate that the proposed methodology makes an effect on recommendation of products in the market which is characterized by a fast fashion and a short product life cycle.

• Journal of KIISE:Software and Applications
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• v.29 no.11
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• pp.785-794
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• 2002

Automatic stock trading systems should be able to solve various kinds of optimization problems such as market trend prediction, stock selection, and trading strategies, in a unified framework. But most of the previous trading systems based on supervised learning have a limit in the ultimate performance, because they are not mainly concerned in the integration of those subproblems. This paper proposes a stock trading system, called R-Trader, based on reinforcement teaming, regarding the process of stock price changes as Markov decision process (MDP). Reinforcement learning is suitable for Joint optimization of predictions and trading strategies. R-Trader adopts two popular reinforcement learning algorithms, temporal-difference (TD) and Q, for selecting stocks and optimizing other trading parameters respectively. Technical analysis is also adopted to devise the input features of the system and value functions are approximated by feedforward neural networks. Experimental results on the Korea stock market show that the proposed system outperforms the market average and also a simple trading system trained by supervised learning both in profit and risk management.

• Journal of Korea Port Economic Association
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• v.30 no.3
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• pp.89-120
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• 2014

The purpose of the study is to suggest a new approach to the terminal operators in order for them to efficiently control their operation cost and support the strategic decision making system and build a performance evaluation process through the systematic cost analysis approach. This study implemented terminal cost analysis based on the traditional cost system, ABC and TDABC and compared the results of each approach. Throughout the study, the usefulness of TDABC was proved in finding operational problems and suggesting countermeasures for improving cost effectiveness and minimizing unused cost.

• Journal of Labour Economics
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• v.30 no.1
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• pp.31-53
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• 2007

This paper, using the sample of male workers in manufacturing industry from the HCCP (Human Capital Corporate Panel) data, analyzes the effects of trade union on the level and dispersion of wages. One of the advantages of the HCCP data is that it enables a researcher to control the effect of individual firm's 'ability to pay' on wage. All relevant variables controlled, the union effect is estimated to be 5-8%. Yet this figure seriously underestimates the wage advantage enjoyed by union workers, because union sets the "price" for experience low and the price for tenure high and at the same time extends tenure of workers by adopting strong employment protection policy. The paper also analyzes the effects of union on the wage inequality. The results are mixed: overall wage inequality is smaller in union sector while standard deviation is larger when all the personal characteristics are controlled.

• Korean Journal of Social Welfare
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• v.58 no.3
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• pp.295-312
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• 2006

The use of the national pension funds to welfare has been criticized due to its low profitability, with concern about financial instability and the lack of funds. Despite the small amount of the funds employed to the welfare, therefore, it has been decreasing so far. It is resulted from the fact that the use of funds to the welfare sector failed to provide its valid reasons, and take the policy direction firmly. There are three main logical reasons for the welfare investment of national pension funds: Firstly, no state is capable to take the full responsibility for the entire social welfare, and therefore, the funds can be used for social welfare. Secondly, the funded system, contrasted with the case of pay-as-you-go system, has inevitably caused discriminations to the present elderly through excluding them institutionally from pension participation. At last, so as to its selective system, the minimum contribution period of 10 years brings about the equity problem between the people who can afford it and the people who hardly can. Therefore, investing a proportion of funds to the welfare is entirely reasonable in that it can alleviate the discriminations to the present elderly generation and the marginal participants, rather than to meet their social welfare needs. With regard to the policy decision, the profitability of the investment, and the choice of the welfare work, on the other hand, the policy direction should be given a sufficient consideration of a various policy factors such as the necessity of social consensus, independence of the welfare work in relations with other national welfare work, policy identity to judge whether the work is worth long-run or short-run, and the reliance of direct-operated work and indirect-operated work. As a result of all these efforts above mentioned, an investment to the welfare of the national pension funds could be vitalized, and gain public confidence.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.237-243
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• 2009

This study was conducted to develop economic injury level (ElL) and economic threshold (ET) of Cabbage armyworm, Mamestra brassicae L. on cabbage (Brassica oleracea L. var). The changes of cabbage biomass and M. brassicae density were investigated after introduction of larval M. brassicae (2nd instar) at different densities: 0, 1, 2, 4, 8, and 16 larvae per plant at 40 d after planting for an open field experiment, and 0, 2, 5, 8 and 12 larvae per plant at 25 d after planting for a glass house experiment. In the field experiment, the yield loss of cabbage was not significantly different among treated-plots at 30 d after the larval introduction, showing an over-compensatory response of cabbage plants to M. brassicae attack. In the glasshouse experiment, however, the biomass of cabbage at 15 d after the larval introduction significantly decreased with increasing the initial introduced number of M. brassicae, resulting in 38.3, 36.7, 21.7, 23.3 and 16.7g in above treated-plots, respectively. The relationship between cumulative insect days (CID) and yield loss (%) of cabbage was well described by a nonlinear logistic equation. Using the estimated equation, ElL of M. brassicae on cabbage was estimated at 44 CID per plant based on the yield loss 14%, which take into account of an empirical gain threshold 5% and marketable rate 91% of cabbage. Also, ET was calculated at 80% of the EIL: 35 CID per plant. Until a more elaborate EIL-model is developed, the present result may be useful for M. brassicae management at early growth stage of cabbage.

• The Journal of Society for e-Business Studies
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• v.21 no.4
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• pp.55-67
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• 2016

Global courier companies have been devoting to get more customers and profits with different service because of the worse profits from price competition. So, the effort of improving satisfaction of customers through improving courier service qualities is more important than any other time. However, the previous way to measure courier service has limitation that costs lots of time and money from off-line survey. This limitation could be overcome with less effort and costs if utilizing on-line social big data analysis and it is so helpful to improve competitiveness of courier companies. Therefore, I have collected comments from domestic and international courier companies from big data on social network service, analyzed the satisfaction of customers by R and verified the result by comparing with American Customer Satisfaction Index (ACSI) and Korea National Customer Index (NCSI) in this research. I found out the result depicts clear correlation between SNS analysis and customer satisfaction. This study can be the foundation to predict customer satisfaction easily by utilizing real time SNS information.