• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.742-750
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• 2020

The flow noise generated by hull appendages is directly related to the performance of the sonar in terms of self-noise and induces a secondary noise source through interaction with the propeller and rudder. Thus, the noise in the near field should be analyzed accurately. However, the acoustic analogy method is an indirect method that is not used to simulate the propagation of an acoustic signal directly; therefore, diffraction, reflection, and scattering characteristics cannot be considered, and near-field analysis is limited. In this study, the propagation process of flow noise in water was directly simulated by using the lattice Boltzmann method. The lattice Boltzmann method could be used to analyze flow noise by simulating the collision and streaming processes of molecules, and it is suitable for noise analysis because of its compressibility, low dissipation rate, and low dispersion rate characteristics. The flow noise source was derived using Reynolds-averaged Navier-Stokes equations for the hull appendages, and the propagation process of the flow noise was directly simulated using the lattice Boltzmann method by applying the developed flow-acoustic boundary conditions. The derived results were compared with Ffowcs Williams-Hawkings results and hydrodynamic pressure results based on the receiver location to verify the usefulness of the lattice Boltzmann method within the near-field range in comparison with other techniques.

• Journal of Arbitration Studies
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• v.27 no.2
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• pp.59-81
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• 2017

The purpose of this study is to find a solution to disputes in the process of producing digital music sources. At present, the center of the world music market including the domestic market has been completely transformed from the tangible musical record market to the intangible sound source market. Due to these environmental changes, the music production process becomes industrialized and specialized, causing conflicts of interest among the individuals in the process. First of all, this study examined changes in the music market which is the background of the dispute, identified the problems of the process and suggested solutions while summarizing the meaning and role of each process of producing a sound source that may arise during the sound production process. This study covers plagiarism between producers, copyright infringement of the creator against assistant creator caused by the industrialization and division of the production environment, issues related to the rights of sound engineers whose role and importance become bigger as acoustic technology develops and music genres become more diverse, and vertical hierarchy due to the formation of oligopoly by several distributors with huge capital. As a result of the study, it was concluded that Alternative Dispute Resolution (ADR) system is suitable for solving these problems. Specific methods of using ADR include activation of the dispute settlement system of the Korea Copyright Commission, active use of the arbitration clause specified in the standard contract, and recalculation of labor costs and earnings from copyright through mutual negotiations. This paper can be differentiated from previous studies in that it studied overall problems that might arise in the process of digital music source production and suggested ADR utilization as the solution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1697-1705
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• 2022

The safety of marine construction workers and marine pollution problems are occurring due to large-scale offshore construction. In particular, underwater construction work in the sea has a higher risk than other work, so it is necessary to apply an unmanned alternative system that considers the safety of the workers. In this paper, the ROV system for offshore construction has been developed for underwater unmanned work. A monitoring system was developed for position control through the control of underwater propellants, pneumatic gripper, and monitoring of underwater work. As a result of the performance evaluation, the underwater movement speed of the ROV was evaluated to be 0.89 m/s, and it was confirmed that the maximum load of the pneumatic gripper was 80 kg. In addition, the network bandwidth required for underwater ROV control and underwater video streaming was evaluated to be more than 300Mbps, wired communication at 92.7 ~ 95.0Mbit/s at 205m, and wireless communication at 78.3 ~ 84.8Mbit/s.