• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.575-576
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• 2014

The Hull Mounted Sonar Dome housing the sonar sensor array is a ship's structure protruded from ship bottom, which is under turbulent flow. The flow of sonar surface is highly disturbed and turbulent. In this case the wall pressure fluctuations within the turbulent boundary layer are one of the most important flow induced self noise sources of the SONAR system. We investigate the characteristics of the wall pressure fluctuations of the hull mounted sonar dome through the model test in the cavitation tunnel. This paper contains the wall pressure fluctuation spectra at various free stream velocities.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.2
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• pp.146-154
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• 2009

Dynamic response of a hull mounted sonar(HMS) to shocks transmitted through hull structures is analyzed and then the structural reliability of the sonars is evaluated. Finite element model of the hull mounted sonar is established and the transient responses to the shock is calculated using MSC.NASTRAN. According to BV043, the maximum allowable accelerations at the foundation of the sonar are converted from the shock spectra allowable for HMS. They are applied vertically and horizontally, respectively, using the large mass method. The structural reliability is evaluated by comparing the von-Mises stresses with the material yield stress. The drum for sensors shows a high reliability owing to mounts by which the shock waves from the base structure are well protected. However, the mounts between the base structure and the drum to mount sensors show a high stress intensity. The base structure also reveals a high stress intensity at the connection points to the hull.

• International Journal of Naval Architecture and Ocean Engineering
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• v.4 no.2
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• pp.96-111
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• 2012

Hull Mounted Sonar (HMS) is a long range submerged vehicle's hull-mounted passive sonar system which detects low-frequency noise caused by machineries of enemy ships or submerged vehicles. The HMS needs a sound absorption /insulation multi-layer structure to shut out the self-noise from own machineries and to amplify signals from outside. Therefore, acoustic analysis of the multi-layer system should be performed when the HMS is designed. This paper simplified the HMS multi-layer system to be an infinite planar multi-layer model. Also, main excitations that influence the HMS were classified into mechanical, plane wave and turbulent flow excitation, and the investigations for each excitation were performed for various models. Stiffened multi-layer analysis for mechanical excitation and general multi-layer analysis for turbulent flow excitation were developed. The infinite planar multi-layer analysis was expected to be more useful for preliminary design stage of HMS system than the infinite cylindrical model because of short analysis time and easiness of parameter study.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.211-217
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• 2010

This paper introduces the Hull Mounted Sonar Vertical Scanning(HMS Verscan) technique to overcome the limitation of target detection in short range shadow zone. Numerical experiments were done with the HMS Verscan taking advantage of the vertical beamforming technique for two-dimension hydrospace(range-depth). For numerical experiments, ray model and high-frequency monostatic reverberation model were used. HMS Verscan increased a sound pressure level at the short range shadow zone through reflections at the sea surface and seafloor. Inclusion of the boundary scattering improved target detection due to the sound reflected into the shadow zone.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.129-137
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• 2008

Hull-Mounted Sonar(HMS) has been the main equipment to detect and track underwater threats like torpedoes and enemy submarines. The HMS has short warming-up time and is employable independently with sea-state and weather condition. But these bad environmental condition and ship maneuvering make ship's roll and pitch. Ship's roll and pitch make unstability of sensor position, then cause degradation of the HMS performance. In this paper, we will show how the unstability influences the HMS performance, propose the 'Beam Stabilization Beamforming Technique' to overcome these phenomenon. And present the effectiveness of proposed technique by comparing with conventional beamforming result.

• The Journal of the Acoustical Society of Korea
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• v.39 no.4
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• pp.237-245
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• 2020

In decades, active sonar, which transmits signals and detects incident signals reflected by underwater targets, has been significantly studied since passive sonar in Anti-Submarine Warfare (ASW) detection performance becomes lowered, as underwater threats become their radiated noise reduced. In general, active sonar using Hull-Mounted Sonar (HMS) adjusts vertical tilt (depression) and sequentially transmits multiple Linear Frequency Modulation (LFM) subpulses which have non-overlapped bands, i. e. 1 kHz ~ 2 kHz, 2 kHz ~ 3 kHz, in order to reduce shadow zones. Recently, however, Generalized SFM (GSFM), which is generalized form of SFM, is proposed, and it is confirmed that subpulses of GSFM have orthogonality among each other depending on setting of GSFM parameters. Hence, in this paper, we applied GSFM to active target detection using HMS to improve the performance by the signal processing gain obtained from enlarged bandwidths of GSFM subpulses compared to those of LFM subpulses. Through simulation, we verified that when the number of subpulses is three, the matched filter gain of GSFM is approximately 5 dB higher than that of LFM.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.349-352
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• 2011

HMS(Hull Mount Sonar) equipment mounted on PCC(Patrol Combat Corvette) is suitably designed for active mode, and the specific character of sensor or system is not appropriate for the frequency range to detect a torpedo. In this article, in order to implement the function of detecting torpedoes with HMS of existing PCC, I will analyze the feature of input signals each PCCs and design a circuit to compensate reversly for the input signal in certain frequency. And also, I will suggest the most adequate torpedo defense system suitable for the special operating environment and the charateristic of naval vessels, implementing functions such as AGC of input signal and fixing the frequency range of different input signals per different warships.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2569-2574
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• 2012

HMS(Hull Mount Sonar) equipment mounted on PCC(Patrol Combat Corvette) is suitably designed for active mode, and the specific character of sensor or system is not appropriate for the frequency range to detect a torpedo. In this article, in order to implement the function of detecting torpedoes with HMS of existing PCC, I will analyze the feature of input signals each PCCs and design a circuit to compensate reversely for the input signal in certain frequency. And also, I will suggest the most adequate torpedo defense system suitable for the special operating environment and the characteristic of naval vessels, implementing functions such as AGC of input signal and fixing the frequency range of different input signals per different warships.

• 전자공학회논문지 IE
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• v.48 no.1
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• pp.25-29
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• 2011

Ryu et al. proposed a multiple target angle-tracking algorithm with efficient equation for angular innovation, and Ryu's algorithm has good feature that it has no data association problem. Ryu's algorithm is only applicable to linear sensor array, because its efficient equation for angular innovation is derived in case of using a linear sensor array. In a many fields studying multiple target angle-tracking, the various shapes of sensor array are used. In sonar, a cylindrical sensor array is as much used as a linear sensor array, a example is hull mounted sonar. In this paper, Ryu's algorithm is modified to be applicable to cylindrical sensor array, and the tracking performance of a modified algorithm is verified by various computer simulations.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.572-578
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• 2011

In this paper, the result of study on the effectiveness of anti-submarine defense plan according to the disposition of surface ships has been proposed. The surface ship carries a hull mounted sonar(HMS) as a underwater sensor and a torpedo acoustic counter measure(TACM) as a soft-kill weapon against torpedo attacks from the enemy. Nowadays these underwater systems have been combined into a integrated anti-submarine warfare combat system. And in the real anti-submarine operation environment, several surface ships cooperate for executing ASW plans. Considering these ASW systems and the ASW environment, the models of underwater systems mounted on an surface ship and the a general model of anti-submarine defense plan are proposed. And we designed a scenario for conducting simulations to evaluate the ASW plan according to the variation of the range and the relative angle between surface ships and a capital ship. The simulation results show the effectiveness of ASW plan depends on the formation of surface ships and a capital ship.