• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.532-537
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• 2015

In this paper, we propose target range estimation method using ghost target in the submarine linear array sonar. Usually, when submarine detect target, they use passive sonar detection to avoid self-disclosure by active sonar transmission. But, originally, passive linear array sonar have limitation for target range estimation and additional processing is required to get target range information. For the case of near-field target, typical range estimation method is using multiple information by multipath effect in underwater environment. Acoustic signal generated from target are propagated along with numerous multipath in underwater environment. Since multipath target signals received in the linear array sonar have different conic angles each other, ghost target is appeared at the bearing different with real target bearing and sonar operator can find these information on the operation console. Under several assumption, this geometric properties can be analysed mathematically and we get the target range by derivation of this geometric equations using measured conic angles of real target and ghost target.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.2
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• pp.115-124
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• 2020

Due to the increasing threats of submarines from North Korea and other countries, ROK Navy should improve the detection capability of submarines. There are two ways to detect submarines : acoustic detection and non-acoustic detection. Since the acoustic-detection way has limitations in spite of its usefulness, it should have the complementary way. The non-acoustic detection is the way to detect submarines which are operating mast sets such as periscopes and snorkels by non-acoustic sensors. So, this paper proposes a new submarine non-acoustic detection model using an ensemble of Convolutional Neural Network models in order to automate the non-acoustic detection. The proposed model is trained to classify targets as 4 classes which are submarines, flag buoys, lighted buoys, small boats. Based on the numerical study with 10,287 images, we confirm the proposed model can achieve 91.5 % test accuracy for the non-acoustic detection of submarines.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.456-464
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• 2013

Passive sonar in submarine can detect the target in long range and can attack using it. There are many noises which can be received at passive sonar of submarine. When noise received in the sonar it make diverse interference pattern depend on the ocean ambient and movement scenario. Interference pattern can be explained by theory of waveguide invariant. In this paper, analyze the interference pattern according to the relative motions of surface ship and submarine. And analyze the occurrence reason of 2 kinds of interference patterns those are usually display on the submarine console. The results show that if relative speed of submarine and target increase then gradient of interference pattern will increase. And closest point approach of submarine and target decrease then gradient of interference pattern will increase. Bathtube pattern usually appear when target pass though close to submarine and Pinetree pattern appear target pass though above of submarine.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.423-431
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• 2022

In this paper, the results of Planar Motion Mechanism (PMM) test for a 1/15 scaled model of the MARIN Joubert BB2 submarine is dealt with to derive the maneuvering coefficients for surface condition. For the depth of surface navigation, the top of the sail was exposed 0.46 m above the water surface in the model scale, and it corresponds to 6.9 m in the full scale. The resistance and self-propulsion tests were conducted, and the model's self-propulsion point was obtained for 1.328 m/s, which corresponded to 10 knots in the full scale. The maneuvering tests were performed at the model's self-propulsion point, and the maneuvering coefficients were obtained. Based on the maneuvering coefficients, a turning simulation was performed for starboard 30 degree of stern fins. The straight-line stability and control effectiveness in the horizontal plane were analyzed using the maneuvering coefficients and compared with the appropriate range. For the analysis of the neutral fin angle of the X-type stern fin, the stern fin test with drift angles was carried out. As a result, the flow straightening effect at lower and upper parts of the stern fin was discussed.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.6
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• pp.697-703
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• 2009

Target Motion Analysis(TMA) means to detect target position, velocity and course for using passive sonar system with bearing-only measurement. In this paper, we apply the TMA algorithm for a submarine with Multi-Sensor Data Fusion(MSDF) and we will decide the best TMA algorithm for a submarine by a series of computer simulation runs.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.404-409
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• 2012

In order to detect and track target, submarine gather the target information(bearing, range, frequency and so on) with using multiple sensors. And submarine can estimate target states with target information. In this paper, we suggest the target motion analysis(TMA) filter architecture of submarine and the proposed TMA filter architecture is tested by a series of computer simulation runs and the results are analyzed and verified.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.5
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• pp.288-295
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• 2022

In this study, the force and moment acting on a Joubert BB2 submarine model at depths near the free surface were measured through a captive model test with the scale ratio of 1/15. Based on the experiment, the pitch moment and heave force due to the "Tail suction effect", including the change in surge force with depth near the free surface, were quantitatively analyzed. The change of force and moment according to the relative position of the sail and the free surface was reviewed with the free surface waves generated for each depths. As a result, the angle of attack of the hull to counteract the pitch moment induced by the tail suction effect was derived. The effect of the hydrostatic moment component according to the angle of attack on the equilibrium of pitch moment was also taken into account. The control plane performance tests for the X-type rudder and sail plane were conducted in snorkel and surface depth conditions to figure out the control plane angles for the neutral level flight of the submarine at near free surface. The results of this study are expected to be used as a reference data for the neutral level flight of the submarine at near free surface operation in the free running model test as well as numerical studies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.581-589
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• 2008

The goal of a simulator is to provide for the testing of new technologies and to facilitate the eventual transfer of these technologies to the applications. In the Development Step, Simulation can provide a cost effective alternative to expensive and hazardous field testing. In this paper, a 3D simulator is developed to test UUV navigation system bated on RVC model. The simulation system consists of a environment manager, objects and a 3D viewer. Objects are modeling all physical elements such as map, obstacle and UUV which reside in a underwater environment. Those objects are created and initialized by environment manager. The environment manager plays the role of intermediator which allows created objects to interact with each other, and transmits information on the objects to 3D viewer. The 3D viewer analyzes the received information and visualizes 3D graphic by using OpenGL primitives.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.125-133
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• 2019

In this paper, a new study was performed on the docking of AUV to docking station using light and light sensor system under the water. For this, a guiding system for AUV loading sensor system composed of lense, light sensor, signal processor, and processor and docking system with LED are proposed. An analysis on light sensor system and light-collecting lense to obtain accurate relative angle and measurement accuracy was performed. To prove this, the system was built and a basic experiment was performed. Finally, the feasibility of the developed docking system was verified the test in the water tank.

• Korean Journal of Ichthyology
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• v.34 no.1
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• pp.44-56
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• 2022

Fish fauna was observed off the coast of Busan (Cheongsapo) and Ulsan (Bangeojin) using underwater visual census from November 2016 to October 2017. A total of 1,486 individuals of 25 species in Cheongsapo and 3,859 individuals of 31 species were identified in Bangeojin. Dominant species in the number of individuals were Trachurus japonicus (20.9%), Halichoeres tenuispinis (12.6%), and Chromis notata (11.9%) in Cheongsapo, Siganus fuscescens (42.0%), Pempheris japonica (8.4%), and Chromis notata (8.0%) in Bangeojin. There was no significant difference in the species composition of Cheongsapo and Bangeojin but spring vs. summer, spring vs. autumn, summer vs. winter, autumn vs. winter showed a significant difference. Contribution species of seasonal differences were commonly high rates by Halichoeres tenuispinis and Parajulis poecilepterus. Of the total 38 species, 17 (44.7%) temperate, 6 (15.8%) tropical, and 15 (39.5%) subtropical species observed coastal waters off Cheongsapo and Bangeojin.