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데이터 마이닝 기법을 통한 COVID-19 팬데믹의 국내 주가 영향 분석: 헬스케어산업을 중심으로
김덕현 ( Kim¸ Deok Hyun ),유동희 ( Yoo¸ Dong Hee ),정대율 ( Jeong¸ Dae Yul ) 한국정보시스템학회 2021 情報시스템硏究 Vol.30 No.3
Purpose This paper analyzed the impacts of domestic stock market by a global pandemic such as COVID-19. We investigated how the overall pattern of the stock market changed due to the impact of the COVID-19 pandemic. In particular, we analyzed in depth the pattern of stock price, as well, tried to find what factors affect on stock market index(KOSPI) in the healthcare industry due to the COVID-19 pandemic. Design/methodology/approach We built a data warehouse from the databases in various industrial and economic fields to analyze the changes in the KOSPI due to COVID-19, particularly, the changes in the healthcare industry centered on bio-medicine. We collected daily stock price data of the KOSPI centered on the KOSPI-200 about two years before and one year after the outbreak of COVID-19. In addition, we also collected various news related to COVID-19 from the stock market by applying text mining techniques. We designed four experimental data sets to develop decision tree-based prediction models. Findings All prediction models from the four data sets showed the significant predictive power with explainable decision tree models. In addition, we derived significant 10 to 14 decision rules for each prediction model. The experimental results showed that the decision rules were enough to explain the domestic healthcare stock market patterns for before and after COVID-19.
Deokhyun Hwang,Jong-Wook Ha,Young Soo Park 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-
Efficient and affordable energy storage systems are indispensable to accomplish a successful energy transitionfrom fossil fuels to renewable sources. Although all-vanadium redox flow batteries (VRFBs) possessmany distinctive advantages and are at an early stage of commercialization, much improvement in theprocess for electrolyte preparation is needed to overcome low productivity and complexity of the currentelectrolysis process. Herein, we demonstrate a simple one-pot process for the preparation of V3.5+(equimolar mixture of V3+ and VO2+) electrolytes from V2O5 by utilizing hydrazine monohydrate as aresidue-free reducing agent and molybdenum as a homogeneous catalyst accelerating the reduction ofVO2+. It is confirmed that the performance of the electrolytes prepared by the newly developed processis identical to that by electrolysis in terms of charge–discharge efficiency and capacity up to current densityof 200 mA/cm2. This study can contribute to the wide spread of VRFBs as a large-scale and long durationstationary energy storage system by providing a scalable and highly reproducible process suitable forthe mass production of V3.5+ electrolyte.
성덕현(Deokhyun Seong) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.11
일관제철소의 모든 공정은 서로 연결됨으로써 단일공정에서의 효율성을 향상시킬 수 있는 최적화도 중요하지만 무엇보다도 전체 공정의 연결 관점에서의 최적화가 중요하다. 일관제철소에서의 경영과학 모형 적용에 관한 조사연구는 대부분 특정 공정만을 대상으로 문제해결을 위한 모형에 집중하고 있거나 혹은 일관제철소에서 발생되는 문제에 대해 어떤 기법이 적용되고 있는지에 대한 조사에 집중되고 있다. 그러나 이보다는 일관제철소에서 해결되어야만 하는 문제를 우선 정의하고, 이를 모형화 할 수 있는 목적과 제약조건 등에 대해 파악하며, 현실적으로 적용 가능한 해를 구할 수 있는 방법론이 무엇인지에 대한 연구가 어떻게 이루어져 왔는지에 대해 조사가 필요하다. 이 연구에서는 일관제철소 공정을 대상으로 생산운영관리관점에서의 효율성 향상을 위해 필요한 연구가 무엇인지를 기술한 후, 이를 해결하기 위해 어떤 연구들이 진행되어 왔는지에 대해 조사하였다. 이를 위해 6가지 영역으로 분류하여 기존 연구에 대해 조사하였으며, 전체최적화 관점에서 향후의 연구방안에 대해 제시하였다. 이를 바탕으로 일관제철소에서의 공정 효율성 제고를 위한 연구주제가 도출될 수 있을 것으로 기대된다. Global optimization that considers the processes at integrated steel mills is more important than the local optimization to improve the efficiency of a single process. Research utilizing mathematical models at integrated steel mills predominantly focus on solving problems solely for a specific process or focusing on what techniques are applied to. However, it is important to define the problems that must be solved at the steelworks, identify the objectives and constraints that can be modeled, and selection of methodologies that can be applied to the problems. The purpose of this study is to investigate the problems in improving efficiency at integrated steel mills from the viewpoint of production & operations management. We review the research have been conducted in order to solve those problems. We classified the research into 6 categories and suggested future research direction based on the global optimization. It is expected that research themes for improving the efficiency at integrated steel mills will be derived.
윤덕현(Deokhyun Yoon),이종홍(Jonghong Lee),유정훈(Junghun Yoo) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_3
Automobile Door Opening Angle Control System has been invented for limiting the opening angle at emergency environment or protecting door scratches while a passenger operates a door. We used topology optimization technique for the link part which transmits the load in the system, and it can also substitute the door impact bar. The system itself can be directly commercialized and equipped to all kinds of automobile door systems.
리튬 이차전지 제조 공정으로부터 발생한 리튬 폐액의 재활용을 위한 전기 투석 수처리 장치의 리튬 농축 효율에 관한 연구
한덕현 ( Deokhyun Han ),정항철 ( Hangchul Jung ),김보람 ( Boram Kim ),김대원 ( Dae-weon Kim ) 한국수처리학회(구 한국수처리기술연구회) 2020 한국수처리학회지 Vol.28 No.5
The rapid market growth in recent years for eco-friendly electric vehicles and more generally, energy storage technologies, has led to an increase in demand for lithium which is a major raw material for lithium secondary batteries. The technology for producing lithium ions from lithium carbonate in seawater 25 L has been developed, but there are about 60 kinds of various ionic components, which is a difficult process, and only about 4 mg of lithium is recovered. In order to meet the demand of lithium, research is being actively conducted to recycle lithium secondary batteries that contain lithium and can be recycled as a circulating resource, but there is little research on recycling of waste liquid generated during the manufacturing process of lithium secondary batteries. Wastewater of lithium is thought to be able to efficiently concentrate lithium metal during recycling using an environmentally friendly electrodialysis water treatment process. In this study, lithium was concentrated using the electrodialysis of wastewater generated during the production of lithium-ion batteries. The efficiency of the electrodialysis varied according to the applied voltage and the volume ratio of the solution. However, due to the disadvantages of employing limited current densities, optimum conditions for the process needed to be selected. Therefore, the concentration efficiency of lithium was confirmed according to the process conditions, and optimum process conditions were derived. Lithium concentrated at the optimum conditions secured a concentration increase of about 128% compared to the initial concentration of wastewater.
리튬이차전지 공정부산물로부터 고효율 리튬 회수를 위한 전기투석 공정의 최적화 연구
한덕현 ( Deokhyun Han ),정항철 ( Hang-chul Jung ),김보람 ( Boram Kim ),김대원 ( Dae-weon Kim ) 한국수처리학회 2021 한국수처리학회지 Vol.29 No.5
Recently, the demand for lithium has increased due to the rapid increase in the eco-friendly electric vehicle and energy storage system industry, and the waste liquid generated during the lithium secondary battery manufacturing process contains about 5000 ppm of lithium. Lithium contained in waste liquid is about 20 times greater than that contained in general seawater. In the case of general process waste, it cannot be reused immediately. But it can be recycled through the water treatment process. Among the various recycling processes, the electrodialysis recycling process uses electrical energy. Therefore, it is an eco-friendly water treatment method that can perform lithium concentration and desalination of lithium waste liquid and simultaneously treat purified water and lithium. In this paper, the electrodialysis optimal process conditions for lithium-containing waste liquids generated during the lithium secondary battery manufacturing process were confirmed. Variables input to the electrodialysis optimal process were combined using the Minitab program, and the individual effects and importance of each reaction were confirmed through Minitab. Analysis result values were identified as the desirability of the multi-response system. The optimization of the process was carried out using a design of experiments method and was performed and analyzed under three conditions: a concentration process, a desalination process, and a concentration and desalination process.
DEA-AR 모형을 이용한 일관제철소 철광석 브랜드별 효율성 평가
성덕현(Deokhyun Seong),변귀원(Gwuiwon Byeon) 한국IT서비스학회 2013 한국IT서비스학회지 Vol.12 No.4
This paper propases a DEA AR model for the efficiency evaluation of the iron ore brands in an integrated steel mill. The input factor is defined as unit cost of each brand based on CIF and two output factors are chosen as Fe and Al which are the important ingredients of iron ore. The relative importance between two output factors is determined by several experts using AHP model. The efficiency of each brand is determined using DEA and DEA AR models. The negative correlation between the DEA AR efficiency and the unit cost (CIF) is shown as significant whereas no significant correlation exist between the efficiency and the output factors. Also, the Kruskal Wallis rank sum test shows that there exist efficiency differences among the iron ore types whereas no difference is shown among the countries. The result could be utilized in selecting good brands of iron ores based on the DEA AR efficiency in an integrated steel mill.