• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.33-40
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• 2014

Due to its unmanned feature and some of being matured underwater technologies, UUV(Unmanned Undersea Vehicle) is increasingly considered as a utility player in today's battle-field. The operational benefit of submarine-based UUV operation could be enormous yet the integration challenges are significant, particularly for most of small conventionally-powered submarines. In this paper, we consider UUV operational methodology via the conventional submarine's torpedo tube. Two previous attempts having been done to retrieve the UUV through torpedo tube are reviewed, and their pros and cons are also analyzed. Then, an alternative option is proposed for UUV operation via torpedo tube. In addition, some of practical challenges are also discussed in the paper.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.89-96
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• 2016

The performance of anti-submarine sonar detection is required to improve by the development of submarine noise reduction technology. because of the need of an anti-submarine detection ability, known for superior beamforming performance, adaptive beamforming algorithms have been considered as an alternative beamforming algorithm of a conventional beamforming algorithm. In order to achieve improved performance by applying an adaptive beamforming algorithm to the sonar system, the adaptive beamforming algorithm applicability of system must be verified, To do this, the performance index for the system applicability must be established. In this paper, a tracking initiation probability of the adaptive beamforming algorithm and the conventional beamforming algorithm was calculated and the performance of both techniques was quantified, a system applicability of the adaptive beamforming algorithm was reviewed.

• Journal of the Korea Society for Simulation
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• v.14 no.2
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• pp.57-71
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• 2005

A simulation for the analysis of the evasive capability of a conventional costal submarine against a light Anti-Submarine Warfare (ASW) torpedo has been studied. The Torpedo, Submarine Controller, Devoy, and Jammer models of this simulation are analysised and designed using Unified Modeling Language (UML) and in addition they are modeled Discrete Event System Specification (DEVS). We examine maximum speed, acceleration, countermeasure systems capabilities of a submarine, and sonar range of a torpedo as the factors which affect the evasive capability of the submarine. This paper shows the relationships between those various factors and the submarine's evasive capability as the outcome of the simulation. The simulation models can be applied for simulation based acquisition (SBA) of a submarine system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.10
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• pp.778-784
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• 2013

In order to develop a LED luminaire for naval-submarines which can replace a conventional one with two-compact fluorescent lamp (CFL) of 18 W, we analyzed the electrical and optical performance of the conventional luminaire. A LED luminaire was fabricated as compact as possible based on the analyzed data. The weight of the prototype LED luminaire is 1.8 kg, reducing up to 58% of the conventional one. The use of LED package for the submarine luminaire could reduce the power consumption from 38 W to 14.5 W with the same optical performance. The reason is that the optical efficacy of the LED luminaire improved by 2.47 times as 61.9 lm/W, compared to 25.1 lm/W for the conventional one.

• Journal of the Korean Electrochemical Society
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• v.13 no.3
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• pp.193-197
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• 2010

In terms of the system efficiency, it is very useful to apply the ejector into the fuel recirculation system of a fuel cell system since the ejector needs no parasitic power to operate. Since the conventional automotive fuel cell use hydrogen and air as their fuel, the only hydrogen is needed to be recirculated for the better fuel efficiency. On the other hand, the submarine fuel cell needs both hydrogen and oxygen recirculation systems because the submarine drives under the sea. In particular, the cathodic recirculation has to meet the tougher target since the oxygen based pressurized stack generally used in the submarine applications generates the significant amount of the water in the stack during the operation. Namely, the oxygen utilization has designed less than 50% in the whole operating range for the better exhausting of the generated waters. And thereby in terms of the oxygen utilization, the entrainment ratio of the ejector should be more than 1 within the whole operating range. However, the conventional ejector using a constant nozzle can not afford to satisfy the mentioned critical requirement. To overcome the problem, the dual-ejector and its control strategy are designed. The performance of the proposed dual-ejector is verified by the experiments based on the real operating conditions of the target submarine system. Furthermore, the proposed design method can be used for the other fuel recirculation system of a large-scale fuel cell system with the critical requirement of the fuel utilization.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.4
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• pp.225-233
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• 2021

Conventional submarine propulsion batteries have mainly used lead acid batteries, which have proved relatively safe, but in recent years, research on mounting lithium-ion batteries to improve the underwater operation capability of submarines is underway in advanced countries such as Japan. Korea has world-class technology in the development of electric vehicles and lithium-ion batteries for energy storage, but fire safety accidents continue to occur in electric vehicles and energy storage lithium-ion batteries. In order to mount the lithium-ion battery in a submarine, it is necessary to check the safety as well as whether the performance is improved compared to the lead acid battery. Through the charge/discharge experiment of this lithium-ion battery module unit, it was possible to measure how much performance was improved compared to the lead acid battery. Safety tests were conducted on the lithium-ion battery module assuming that it was mounted on a submarine, and it was confirmed that safety was secured when applied to a submarine. Since many modules are mounted on actual submarines, it has been confirmed that it can be applied to submarine systems by simulating charge/discharge characteristics through Hardware-in-the Loop(HILS). Through the results of this study, the application of lithium-ion batteries to submarines is expected to significantly improve the sustainability of underwater operations.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.369_370
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• 2009

This paper describes the fault location method for HVDC submarine cables. Most conventional fault location methods can be applied in off-line. However, in this paper, on-line fault location algorithm is proposed using multi-scale correlating of wavelet coefficient and travelling wave. The propagation velocity is measured by field test on Jeju-Heanam submarine cable section. Finally, the fault location algorithm is tested by same system modeling using EMTP/ATP.

• Strategy21
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• s.40
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• pp.82-114
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• 2016

The purpose of this article is to analyze the progress of North Korea's SLBM threat, and to assess the technological capacity and threat level of its SLBMs. Currently, North Korea has approximately 1000 ballistic missiles, such as the SCUD, Musudan, and Nodong, in stock. This article pays close attention to the background and strategical implication behind North Korea's obsession with developing SLBMs despite possessing sufficient means to launch provocations with its current arsenal of ground based ballistic missiles and conventional weapons. Based on the abovementioned analysis, this article will recommend possible response directions for the ROK Armed Forces to North Korea's SLBM threat. It is highly difficult to detect SLBMs due to its stealthy nature, as it is launched underwater after covert infiltration. North Korea's SLBM is considered a game changer in that even one SLBM can significantly change the strategic balance of North East Asia. North Korea's SLBM test launch in August has made a 500km flight, landing 80km inside the JADIZ (Japan Air Defense Identification Zone), and as such, it is assessed that North Korea already possesses underwater ejection and cold launch capabilities. The most realistic response to North Korea's imminent SLBM threat is bolstering anti-submarine capabilities. ROK Armed Forces need to upgrade its underwater kill-chain by modernizing and introducing new airborne anti-submarine assets and nuclear-powered submarines, among many options. Moreover, we should integrate SM-3 missiles with the Aegis Combat system that possess strong detection capabilities and flexibility, thereby establishing a sea-based Ballistic Missle Defense (BMD) system centered around the Aegis Combat System, as sea-based ballistic missile threats are best countered out in the seas. Finally, the capabilities gap that could arise as a result of budgetary concerns and timing of fielding new assets should be filled by establishing firm ROK-US-Japan combined defense posture.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.63-69
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• 2006

The optical submarine cable has a long distance cable and the repeater for optical amplification compared to territorial optical cable so conventional OTDR utilization for the optical submarine cable is limited. in case the optical core in the optical submarine cable system cut, by using Coherent OTDR that utilize OTDR path in repeater the cable fault point can be detected and in case the faulty of the copper tube in the cable that provide power for the repeater to amplify optical signal, the ways using the current/voltage characteristic, the capacitance per Km and so on is required. this report suggest efficient fault location detecting mechanism by categorized cable fault type.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.1
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• pp.128-141
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• 2015

Independent Component Analysis (ICA), one of the blind source separation methods, can be applied for extracting unknown source signals only from received signals. This is accomplished by finding statistical independence of signal mixtures and has been successfully applied to myriad fields such as medical science, image processing, and numerous others. Nevertheless, there are inherent problems that have been reported when using this technique: instability and invalid ordering of separated signals, particularly when using a conventional ICA technique in vibratory source signal identification of complex structures. In this study, a simple iterative algorithm of the conventional ICA has been proposed to mitigate these problems. The proposed method to extract more stable source signals having valid order includes an iterative and reordering process of extracted mixing matrix to reconstruct finally converged source signals, referring to the magnitudes of correlation coefficients between the intermediately separated signals and the signals measured on or nearby sources. In order to review the problems of the conventional ICA technique and to validate the proposed method, numerical analyses have been carried out for a virtual response model and a 30 m class submarine model. Moreover, in order to investigate applicability of the proposed method to real problem of complex structure, an experiment has been carried out for a scaled submarine mockup. The results show that the proposed method could resolve the inherent problems of a conventional ICA technique.