• 한국안전학회지
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• 제25권5호
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• pp.15-21
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• 2010

Regenerative Energy Storage System(ESS) is a system that saves regenerative energy which generated instantly in the regenerative braking of Electric Multiple Unit(EMU) and disappear, and reuse the stored energy when EMU is in powering. Such system related to a research field of renewable energy which emerged concerning climate change and high oil prices. In the case of existing domestic rolling stock, about 25% to 30% of generated regenerative energy is restored to power source and is regarded as direct factor of raising catenary voltage. Such rapid change of catenary voltage is a cause of the failure of EMU's electronic equipment and lowering its reliability and is also a cause of train's fault occurred by tripping circuit breaker. In this paper, we intend to investigate the effect on blending characteristics of electric-braking and pneumatic-braking whether the regenerative energy storage system is used or not in urban transit DC 1,500V feeding system, while trains run. And we also intend to investigate its effect on stabilization of the blending, fluctuation of catenary voltage and various electric equipments.

• Journal of Construction Engineering and Project Management
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• 제4권4호
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• pp.1-8
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• 2014

The broad aim of this paper is to provide a detailed understanding of the post-war problems associated with materials for reconstruction in Libya, and to identify key problems and obstructions. Theoretical and empirical studies are being conducted in Libya. The theoretical study focuses on materials for construction and the key issues such as sources, transport and storage of materials, as well as their impact on the national economy, the nation's socio-economic development and the environment. This empirical study employed questionnaires, observations and a series of interviews with researchers, academics, suppliers and manufacturers, supported by the researcher's three decades of experience of working in the construction industry and its associated processes and operations. The empirical study illustrated that materials for post-disaster reconstruction in Libya suffer from external problems related to policies and decision-making in terms of availability of materials, fluctuation of prices of materials, specifications, building codes, legislation and regulations, and internal problems related to the construction and building material's key players: construction companies, consultancy firms, manufacturers and suppliers.

• 한국미생물·생명공학회지
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• 제38권3호
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• pp.244-254
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• 2010

The trend toward intensification of livestock raising, confinement in barn has increased in recent days. The move toward concentrated animal feeding operations reduces per unit costs and permits farmers to better earnings in spite of fluctuation in hog prices. However, this also results in outbreaks of a lot of animal wastes and odorous compounds. Emissions of these malodorous compounds produced from concentrated animal feeding operations have become a concern for both public and regulatory agencies and are causing the complaints of residents in rural area. For competitive sustainable swine production industry, odor management plans systematically identify potential odor sources, determine control strategies to reduce these odors, and establish criteria for implementing these strategies. Since, the malodor originates from microbial activities involving a variety of microbes, understanding the characteristics of the microflora present in swine manure is essential for developing effective odor control techniques. This paper reviews the available information in the literature related to the types of bacteria in swine manure, the potential odorous compounds associated with different bacterial genera, and the corresponding techniques used to control odor based on microbiological principles.

• 지역연구
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• 제32권1호
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• pp.3-26
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• 2016

본 연구의 목적은 최근에 개통된 대구도시철도 3호선 건설과 역세권 아파트가격 간의 관계를 이벤트 스터디(event study) 기법을 적용하여 실증적으로 분석하고, 역세권 아파트가격에 영향을 미치는 요인들을 탐색하는 데에 있다. 역세권 아파트가격의 영향요인 탐색을 위해서는 선행연구의 한계를 고려하여 아파트 면적과 역세권 거리 구분 변수를 분석모형에 포함하였다. 주요 분석 결과를 요약하면 다음과 같다. 첫째, 대구도시철도 3호선 건설 착공시작시점보다 공사완료시점에서 역세권 아파트가격 상승이 더 크게 나타났다. 둘째, 대구도시철도 3호선 개통으로 인한 접근성 향상이 아파트가격 상승에 긍정적인 영향을 미치고 있는 것으로 나타났으며, 특히 역 반경 200~600m 이내의 아파트가격 상승이 가장 높은 것으로 나타났다. 셋째, 아파트 면적별로는 중대형 및 대형 아파트가격이 소형 아파트가격에 비해 상대적으로 대구도시철도 3호선 건설에 더 민감하게 반응하였음을 확인할 수 있었다. 넷째, 자치구별로는 북구와 수성구 지역의 아파트들이 가격 측면에서 대구도시철도 3호선 개통으로 보다 많은 혜택을 누리고 있는 것으로 나타났다. 본 연구의 이와 같은 분석결과는 향후 도시철도 건설에 따른 개발이익에 대한 과세, 피해부담집단에 대한 재분배정책 등에 관한 중요한 정책적 시사점을 제공해주고 있다.

• The Journal of Asian Finance, Economics and Business
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• 제7권11호
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• pp.13-22
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• 2020

This research explores the appropriate rubber pricing model and the consistent empirical evidence. This model has been derived from the utility function and firm profit-maximization model of commodity goods. The finding shows that the period t - 1 affects expected commodity price and expected profit of commodity production. In fact, a change in the world price of rubber in the past period led to a change in the expected price of rubber in the short run which influenced the expected rubber profit. As a result, the past-period free on board price has an entirety effect on expected farm price of rubber given an exchange rate. In addition, the rubber pricing model indicates that the profit of local farmer on rubber plant depends solely on the world price of rubber in the short run in case of Thailand. In an empirical study, it was found that a change in the price of ribbed smoke sheet 3 in Singapore Commodity Exchange significantly and positively determined the fluctuation of rubber price at the farm gate in Thailand which was consistent with the behavior of the Thai farmers. Both prices are also cointegrated in the long run. That is, the result states that the VECM is an appropriated pricing model for forecasting the farm price in Thailand.

• 한국주거학회논문집
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• 제22권1호
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• pp.11-23
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• 2011

The purpose of this study is to explore cohort changes in first-time homeownership in Korea. The study collected qualitative data from individual interviews to explore the housing trajectories of different birth cohorts. As a result, Individual interviews facilitated an exploration of the decision making process of first-time homeowner with in a cohort context. The cohorts born in the 1950s seek a sense of security through homeownership, and have strong Korean sentiments of ownership. They tried various means to buy a house, and real estate market boom at that time played a role in the driving force. The cohorts born in the 1960s have less insecurity of tenure than the previous cohorts, but they still feel the need for homeownership. Since the currency crisis in 1997 caused the fluctuation of housing price, the 1960s cohort experienced a dramatic decline and rebound of assets while the previous cohorts had experienced a steady rise in housing prices. Finally, the attitude towards housing in the group of 1970s cohorts has changed from ownershiporiented to use-oriented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권9호
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• pp.3126-3145
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• 2014

Cloud computing is a computing paradigm in which users can rent computing resources from service providers according to their requirements. A spot instance in cloud computing helps a user to obtain resources at a lower cost. However, a crucial weakness of spot instances is that the resources can be unreliable anytime due to the fluctuation of instance prices, resulting in increasing the failure time of users' job. In this paper, we propose a Genetic Algorithm (GA)-based workflow scheduling scheme that can find the optimal task size of each instance in a spot instance-based cloud computing environment without increasing users' budgets. Our scheme reduces total task execution time even if an out-of-bid situation occurs in an instance. The simulation results, based on a before-and-after GA comparison, reveal that our scheme achieves performance improvements in terms of reducing the task execution time on average by 7.06%. Additionally, the cost in our scheme is similar to that when GA is not applied. Therefore, our scheme can achieve better performance than the existing scheme, by optimizing the task size allocated to each available instance throughout the evolutionary process of GA.

• The Journal of Asian Finance, Economics and Business
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• 제9권5호
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• pp.285-294
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• 2022

Using the ARDL approach, this study examined the impact of macro factors on Vietnam's stock market in the short and long run from 2010 to 2021. The State Bank of Vietnam and the International Monetary Fund provided time series data for this study. Research results show that in the long run, money supply and exchange rate respectively affect the stock market. The money supply had a positive effect on the VN-Index, while the exchange rate showed the opposite effect. However, the study did not find a relationship between world oil price and interest rates on VN-Index in the long run. On the other hand, in the short term, there are relationships between variables; specifically, interest rates and exchange rates have a negative impact on the VN-Index, while the world oil price and the fluctuation of money supply M2 of the previous one and two months showed an impact in the same direction on this index. The differences in the regression results on the impact of exchange rate and oil price on the VN-Index compared to previous studies come from the characteristics of Vietnam's stock market, with the large capitalization of companies in the oil and gas sector, and the structure of Vietnam's economy with export heavily depends on FDI sector.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.959-964
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• 2006

Recently, an international oil price shows fluctuation in 70 dollars per barrel and it is said that this trend is able to continues for much longer. Because energy consumption in buildings accounted for about 25% of the nation's total demand for energy, Energy censervation and efficiency of buildings were very important issues. Main political measures relating to building energy use and saving were 'the system of accrediting green building', 'building energy certification system', 'energy consumption efficiency rating indication system', 'building energy code', 'high efficient energy materials certification system'. This paper presents approaches to improve building energy efficiency policy.

• Industrial Engineering and Management Systems
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• 제9권3호
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• pp.227-241
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• 2010

A memory module industry's supply chain usually consists of multiple manufacturing sites and multiple distribution centers. In order to fulfill the variety of demands from downstream customers, production planners need not only to decide the order allocation among multiple manufacturing sites but also to consider memory module industrial characteristics and supply chain constraints, such as multiple material substitution relationships, capacity, and transportation lead time, fluctuation of component purchasing prices and available supply quantities of critical materials (e.g., DRAM, chip), based on human experience. In this research, a directed graph-based supply network planning (DGSNP) model is developed for memory module industry. In addition to multi-site order allocation, the DGSNP model explicitly considers production planning for each manufacturing site, and purchasing planning from each supplier. First, the research formulates the supply network's structure and constraints in a directed-graph form. Then, a proposed genetic algorithm (GA) solves the matrix form which is transformed from the directed-graph model. Finally, the final matrix, with a calculated maximum profit, can be transformed back to a directed-graph based supply network plan as a reference for planners. The results of the illustrative experiments show that the DGSNP model, compared to current memory module industry practices, determines a convincing supply network planning solution, as measured by total profit.