• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.330-335
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• 2017

This study applied SONAR(Sound Navigation And Ranging) to the inspection and evaluation of underwater structures. Anactual river bridge was chosen for inspection and evaluation. SONAR and an optical camera were operated together to analyze the underwater image of the bridge. SONAR images were obtained by various methods to remove the environmental variables from the field experiment, and it was confirmed that the reliability of detecting damaged areas on piers was decreased when using SONAR alone. The SONAR equipment and the optical camera can be used simultaneously to overcome the limitations of SONAR in inspecting underwater structures.These results can be used as basic data for the development of similar technologies for underwater structure inspection.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.1
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• pp.95-104
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• 1997

This paper deals with an analysis of multipath which affect a transmission performance in underwater acoustic channel. For the test of autonomous underwater vehicle(AUV), underwater acoustic channel with multipath structure is introduced to mathmatical modelling for a basin environment. In this paper, SMR(Signal to Multipath Ratio) which is defined as a parameter of mulipath's effect is presented as a mathmatical equation, and the equation or SMR is simulated by MATLAB program.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.468-472
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• 2000

This paper discusses the development of a acoustic vector channel simulator for the performance analysis of a acoustic digital communication system. The channel simulator consists of transmission module, acoustic channel model, receiver, beamformer, and adaptive equalizer. QPSK source signal is generated by the parameters specified by a user and transmitted. The transmitted signal generate multipath signals which have a different delay, amplitude, and dopper Sequency. The multipath signals with the acoustic noises is the received signal. We can analysis the communication system performance according to the antenna structure, beamforming algorithm, and equalization algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.861-868
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• 2000

This paper discusses the development of an acoustic vector channel simulator for the performance analysis of an acoustic digital communication system. The channel simulator consists of transmission module, acoustic channel model, receiver, beamformer, and adaptive equalizer. QPSK source signal is generated by the parameters specified by a user. The transmitted signal generates multipath signals which have a different delay, amplitude, and dopper frequency. The multipath singnals with the acoustic noises are the received signal. This paper presents the performance analysis of an acoustic digital communication system according to the antenna structure and the various baseband signal processing techniques.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.42-48
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• 2006

This paper proposes the new efficient system design strategies for the acoustic-based underwater multiple modem and media access control protocol. The system aims to establish the acoustic-based communication network of an underwater vehicles for deep sea mining, which ensures a certain level of maximum throughput regardless of the propagation delay of acoustic and allows fast data transmission through the acoustic-based multiple channel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.235-242
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• 2006

This paper proposes the new efficient system design strategies for the acoustic-based underwater communication system and it's media access protocol, which make it possible to control the multiple vehicles for underwater duty working by the surface plant. For an approach to implementation of the system, it is inevitable to establish acoustic-based underwater digital communication network to exchange the information between a surface plant and multiple vehicles in underwater.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.131-132
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• 2017

본 논문에서는 수중 초음파 전송을 이용하여 해양 사고 발생 시 수중 실종자의 신원과 위치를 파악할 수 있는 재난 대응 시스템을 제안한다. 실종자 몸에 부착된 초음파 발생기에서 나온 신호를 해상에 배치된 다수의 하이드로폰 센서 노드에서 감지, 분석해 저전력 통신으로 선박 등에 설치된 중앙 제어시스템에 보내면 이를 분석해 실종자의 위치 등을 판별할 수 있어 수색 작업에 큰 도움이 될 것으로 기대된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.118-125
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• 2014

As the earth's current global warming has caused elevation of sea water temperature, size of storms is foreseen to increase and consequently large damages on port facilities are to be expected. In addition, due to the improved processing efficiency of port cargo volume and increasing necessity for construction of eco-friendly port, demands for various forms of port facilities are anticipated. In this study, two kinds of nondestructive evaluation (NDE) techniques (rebound hardness and ultrasonic pulse velocity methods) are investigated for the effective maintenance of smart green harbor system. A new methodology to estimate the underwater concrete strengths is proposed and its feasibility is verified throughout a series of experimental works.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.381-384
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• 2000

초음파 음장의 상대적인 변화를 측정하는데 사용하기 위한 극소형 수중 청음기를 제작하고 그 특성을 평가하였다. 압전체로서는 PVDF(Poly Vinylidene Di Fluoride) 고분자막을 사용하였으며, 수신 특성을 향상시키기 위해 임피던스 변환회로를 부가하였다. 본 논문에서는 설계된 수중 청음기의 초음파 수신특성을 Mason 등가회로에 의해 이론적으로 평가한 결과 및 극소형 수중 청음기의 제작 방법, 그리고 제작한 청음기의 초음파 수신 특성에 대하여 보고한다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.2
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• pp.56-62
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• 1998

전기-기계변환효율이 좋은 PZT를 송신용으로, 대역특성이 우수한 PVDF를 수신용 으로한 PZT/PVDF 복합구조 수중초음파 트랜스듀서를 제안하고, 외부는 PZT, 내부는 PVDF로 된 동심원형의 트랜스듀서를 설계·제작하여, 그 특성을 이론적, 실험적으로 파악 하였다. 삽입손실과 임펄스 응답파형에 대한 등가회로해석 및 측정결과로부터 제안한 트랜 스듀서의 특성, 특히, 대역폭이 종래의 PZT 단일소자에 의한 트랜스듀서보다 향상될 수 있 음을 알았다.