• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.267-278
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• 2018

The purpose of this study is to analyze how the vertical integration, which is the main characteristic of the domestic digital music market, appears in each period and how these phenomena affect the digital music market. As a result, we could find out that the domestic digital music market is a vertically integrated market centered on ISPs. There were a variety of subjects that led the digital music market from the early digital music in 2000s to the latest streaming market. However, ISP was the only subject that vertically integrated all aspects of content, distribution, and consumption through its subsidiaries and affiliated companies. A variety of combined services, supplementary services, and fare plans provided by using its platform and network have become mainstream services in the domestic digital market and have fixed the current transaction type in domestic market.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.2
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• pp.164-171
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• 2004

Active control techniques have been used in wide areas of noise and nitration control engineering and a noise barrier is one of them. Omoto's work in 1993 would be one of the fundamental and systematic studies on the actively controlled noise barrier, in which he used equal number of control sources and error sensors. The error sensors were placed uniformly along the top edge of the noise barrier with equal distance apart and the control sources were placed in the exactly same way some distance apart from the error sensors. Since then, a couple of studies were made on the secondary sources'arrangement rather than the optimality of secondary source positions. Shao's results showed that arc shaped arrangement for secondary sources is better than the straight line one, and later work of Yang showed that the more important factor is the average distance between the primary source and secondary sources. However, since these studies were all executed with a simple uniform distribution of the secondary sources along the straight line or arc, it is difficult to conclude which arrangement is superior In order for the fare comparison. the optimality of the source positions in each arrangement must be given in prior. The primary goal of this study is focused on this aspect and some major factors were investigated and compared. The computer simulation results showed that the arc shaped arrangement is marginally better than the straight line one, and more importantly slightly tuned position can greatly improve the performance of the control system.