• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.869-874
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• 2002

Hermetic rotary compressor is one of the most important components for air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration of rotary compressor is occurred due to gas pulsation during compression process and unbalanced dynamic force. In order to reduce noise and vibration, It is necessary to identify sources of noise and vibration and effectively control them. Many approaches have been tried to identify noise sources of compressor. However, compressor noise source identification has proven to be difficult since the characteristics of compressor noise are complicated due to the interaction of the compressor parts and gas pulsation. In this work, Statistical Energy Analysis has been used to trace the energy flow in the compressor and identify transmission paths from the noise source to the sound field.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.1
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• pp.68-77
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• 2020

The shipbuilding and offshore industry is a large and complex assembly industry, which causes many safety accidents. The major accidents in the shipbuilding and offshore industry workplaces are stenosis, falling objects, dust, fire, explosions, and gas poisoning. The accident by worker in this industry mainly has three factors: frequent movement, narrow work space, and increased use of subcontractors. To control these factors, it is necessary to monitor the worker's location and work status. In this paper, a worker location monitoring system using inaudible sound wave was designd that can be used in environments with many metal barriers. The process included deriving stakeholder requirements, transforming to system requirements, designing system architecture, and developing prototype. The prototype was validated by third-party testing agency. As a result, it satisfied the designed performance and verified its feasibility.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.9-13
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• 2009

A cause of noise and vibration which come from a Combustion of gas heater are a combustion roar and Combustion oscillation. A character of a combustion roar is that sound pressure is distribute with broad band frequency. otherwise, The presence of combustion oscillation caused by positive Feed Back in Combustion Chamber break out a noise and vibration. Accordingly, The method that be solved a noise and vibration is to make each natural frequency different frequency. first, in order to solve problem, we control ratio of fuel and air. that is, Keep away resonance. second, in order to changing natural frequency of Combustion Chamber, We changed the shape of Economizer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.111-118
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• 2006

Relatively high noise emitted from Transformers of in-door-substation in urban area has become the target of public complaints and the frequency is on the rise in these days due to an extension of transformer installations and new establishment of substations. The noise consist of harmonics of a specific frequency of the twice of the electricity frequency(60[Hz]), which is hard to control by using the general sound proofing techniques. In this work, several effective methods were discussed for reducing the noise from a transformer, which is transmitted through explosion preventing shutter and air tunnels. By applying to the actual site, the effects of the methods were verified.

• Ocean and Polar Research
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• v.23 no.3
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• pp.279-284
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• 2001

The natural high productivity of temperate coastal waters in Korea can be used in advantage to reduce the feed costs for the cage-cultured marine carnivorous fish species. By using the night-lights methods an alternative of supplementary feeding strategy can be offered to the cage farmers and maintain sound environmental conditions that could enhance maximum sustainable yields. The aim of this study was to investigate the effects of night-lights which shown positive results on feeding and growth in sea cage cultured rockfish, Sebastes schlegeli. The study showed that for the water around overhead illuminated sea cage, higher zooplankton density was observed at night than during the daytime. Increased amounts of for-age, evidenced by stomach content analyses were observed in the early evening, but decreased amounts were observed in the morning and afternoon. That is, feeding activities of the fish were most intensive from midnight to dawn. In a three month feeding experiment, the results showed that night-lighted groups were superior to groups with the highest feeding efficient. This study suggested that the evidence that night-lights superimposed on only day-lights enhance growth of rockfish in sea cages during summer and winter, with timing of exposure affecting growth of juvenile fish. The capability to control the feeding behavior of marine life via manipulation and external stimuli could considerably benefit the advancement of sea cage aquaculture in coastal areas.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.17-20
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• 2013

In this study, we introduce an LED Driving circuit in order that the information state can indicate audio signal gain and radiate pattern of ultrasonic speaker system for a sign board. Ultrasonic speaker system decreases energy loss and transmits the sound farther. Ultrasonic speaker having such characteristics is useful in that it can be widely used in daily life. Additionally, Proposed LED circuit indicates the information state as linear LED brightness taken from interface of ultrasonic speaker system. Designed circuit is confirmed through $0.35{\mu}m$ CMOS process by Dong-bu.

• The Journal of the Korea Contents Association
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• v.7 no.10
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• pp.80-88
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• 2007

Applying Visual Art to pop music performance is gradually increasing. A video editor which simply mixes a number of images was mainly used in the past, but now various computer software make it easy to control visual art by development of computer technology, and it became possible for you to express unique and inimitable idea as well. Compare that a complicated equipment which makes them spend much expense and time was only used in the big size of concert hall in early days, a small and simple one now helps you easily apply your idea to Visual art in Pop music performance even in the small club. The technic of Visual art is being developed gradually especially by using computer The point of this study is how to apply real-time interaction between sound and visual image to interactive media art.

• Journal of the Korea Computer Industry Society
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• v.2 no.3
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• pp.377-388
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• 2001

Software metrics provide effective methods for characterizing software. Metrics have traditionally been composed through the definition of an equation, but this approach restricted within a full understanding of every interrelationships among the parameters. This paper use fuzzy logic system that is capable of uniformly approximating any nonlinear function and applying cognitive psychology theory. First of all, we extract multiple regression equation from the factors of 12 software complexity metrics collected from Java programs. We apply cognitive psychology theory in program volume factor, and then measure program volume complexity to execute fuzzy learning. This approach is sound, thus serving as the groundwork for further exploration into the analysis and design of software metrics.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1781-1786
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• 2005

In sensor network systems, all the nodes are interconnected and the positional information of each sensor is essential. To measure the temperature, position detection and communication functions are required. Many sensor nodes are distributed to a measurement field, and these sensors have three main functions: they measure the distance to the other nodes, the data of which are used to determine the position of each node; they communicate with other nodes; and they measure the temperature of each node. A novel range measurement method using the difference between light and sound propagation speed is proposed. The experimental results show the temperature distribution as measured with the aid of the determined positions. The positions of every node were calculated with a PC program. Eight nodes were manufactured and their fundamental functions were tested. The results of the range measurement method, which takes relatively accurate measurements, contribute significantly to the accuracy of the position determination. Future studies will focus on 3-D position determination and on the architecture of appropriate sensors and actuators.

• Journal of Information Technology Applications and Management
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• v.15 no.1
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• pp.99-116
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• 2008

This study explores the impacts of e-learning system characteristics on learner committment and satisfaction by surveying the firms utilizing e-learning systems for learning. In the study, we have, first, drawn the key factors and instruments to measure e-learning system characteristics through intensive literature review. Second, we have investigated whether the characteristics contribute to increasing learner's commitment and satisfaction. Finally, we have examined the mediating effect of learner's commitment between the characteristics of e-learning system and learner satisfaction. We have conducted a survey on the employees having experience in using e-learning systems for learning, and collected a total of 93 responses. The results of a statistical analysis show the following: First, expression and interaction affect the learner's commitment. The results indicate that a learner should engage in e-learning and ultimately be more committed on it when there is a coherence in design and organization of learning contents, and when the system offers various multimedia options including audio, sound, image, graphics, etc. Second, leaner's commitment leads to higher learning satisfaction. Finally, our results show that the commitment plays a mediating role between learner characteristics (expression, control, and trust) and learner satisfaction.