• Journal of Ocean Engineering and Technology
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• v.19 no.5 s.66
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• pp.78-82
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• 2005

The motion response results of a submerged submarine section in waves are presented. The numerical method is based on Cauchy's integral and 3 degrees-of-freedom motions of submarine sections are calculated in two dimensions, in regular waves. The fully nonlinear free surface and body boundary conditions are applied to the present problem, and the viscous effects on the submarine are modeled by Morison's formulas. The motions of submarine sections in beam sea are directly simulated and the effects of wave frequency, snorkel depth, and bridge are discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1330-1334
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• 2012

The submarines reach their weakest point when they sail on the surface to operate snorkel and periscope. At this period, however, there lies a high possibility that the submarines are detected by non-acoustic sensors such as radars, IR signatures, and human observations. In this paper, the non-acoustic stealth was adopted on the mast and periscope of submarines so as to overcome their vulnerability of being easily detected in this given situation. First of all, the non-acoustic detection sensors were investigated and the stealth methods were analyzed. And multi-layered structures consisting of RAM layer, IR layer, and Camouflage layer were proposed on the surface of the submarine. As a results, multi-layered structure was suggested with 3~5 mm of a magnetic material such as ferrite for RAM layer, 1~2 mm of ceramic or nickel for IR layer, and sea-blue paint for Camouflage layer.

• ALGAE
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• v.22 no.1
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• pp.37-44
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• 2007

In order to understand the impact of the heavy-oil pollution by the 1997 Nakhodka oil spill on the intertidal macroalgal vegetation, we have been monitoring succession in the intertidal flora since 1997 at Oh-ura, Takno, and Imago-Ura Cove, Kasumi in Hyogo Prefecture, northwestern coast of Honshu, Japan. We employed two different monitoring methods: 1) The percent cover of macro-algae (seaweeds) in 1 x 1 m quadrats along 450 m intertidal transects parallel to the shoreline were assessed and recorded by photographic imaging until 2002, and for 30-40 m transects of the most heavily polluted areas in 2004 and 2006; 2) The percent cover of macro-algae in 0.5 x 0.5 m quadrats along a transect line perpendicular to the shore were recorded and all macrophytes within the quadrat were completely removed to record the wet weight of each taxon (1997-2006). Based on the monitoring data, we conclude that the high intertidal zone at Imago-ura, where a large part of the stranded oil accumulated, suffered the heaviest damage and experienced the slowest recovery. In addition, although the original status of macroalgal vegetation before the impact was not well-documented, it appeared that recovery from the damage caused by the oil pollution required four to five years.

• 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 Korea Society of Industrial Information Systems
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• v.28 no.6
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• pp.99-105
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• 2023

Submarines, which require a high degree of survivability, are among the most critical combat weapon systems in military strategic assets. Conventional submarines need air to operate their propulsion systems. Exhaust gases released into the water during snorkel navigation heat the surrounding fluid, producing a temperature wake. This wake, in turn, reduces the submarine's survivability. In this study, we conducted a preliminary experiment on the temperature traces formed by an underwater submarine's waste discharge. For this purpose, we collected propulsion system and navigation condition data from domestically introduced submarines and developed an experimental system to measure the temperature traces. As a result, we observed that high-temperature bubbles injected into the tank broke down into smaller sizes, and their temperature dropped to levels similar to the surrounding fluid. This observation was confirmed using a thermocouple sensor. Consequently, the thermal imaging system designed to measure the temperature trace of the water's surface did not detect any significant temperature traces.

• Strategy21
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• s.41
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• pp.261-293
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• 2017

Nuclear power is a way of attaining an enormous amount of energy with relatively small amount of resources and after it has been introduced to the submarine since 1954, there are approximately 150 of nuclear powered submarine currently on a mission around the world. This is due to the maneuverability, mountability and covertness of nuclear submarines. However, there are other tasks, not only the high level of nuclear technology that are needed to be dealt with in order to construct nuclear powered submarine. The biggest task of all is to secure the enriched uranium. Accordingly, this research is about the way of enriching and securing the nuclear fuel that are used in the nuclear submarine with the characteristics, merits and demerits of the nuclear submarine. Due to the fact that the pressurized water reactor in South Korea is the reactor that was originally built for the development of nuclear powered submarine, many parts is designed to be suitable for the submarine propulsion. However, in order to apply this to submarine it is needed to consider additional requests such as the position of reactor, accident-coping system, radioactive covering, reactor output adjustment and ship's pitch and roll in order to apply this to submarine. Nuclear submarines have much higher speed based on the powerful propulsion in comparison with diesel-electric submarine and also have bigger loading area. Besides, there is no need to snorkel and they also have advantages in covertness with the multi-noise proof system. The nuclear technology in South Korea has seen the dramatic development since 1962 and in 1998 reached to the level that we have succeeded in the localization of nuclear plant and exported the world-class one-piece small-sized reactor (SMART) to UAE. To operate these reactors, we import the whole quantity of low-enriched uranium and having our own uranium enrich facility is not probable because of the budget and international regulations. With the ROK/US nuclear agreement revised on 2015 November, the enrichment of uranium that are available without special permission has changed up to 20%. According to the assumption that we use the 20% enrichment of Uranium on U.S. virginia class submarine, it is necessary to change the fuel after 11 years and it will cause additional cost of 1 billion dollars. But the replace period by the uranium's enrichment rate is not fixed so that it is possible to change according to the design of reactor. Therefore, I would like to make a suggestion on two types of design concepts of nuclear submarine that can be operated for 30 years without nuclear fuel change by using the 20% enriched uranium from ONNp.First of all, it is possible by increasing the size of reactor by 3 times and it results in the 1,000t increase of the weight. And secondly, it is by designing the one piece reactor to insert devices such as steam turbine, condenser into the inside of nuclear core like the Rubis class submarines of France.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1604-1610
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• 2017

Using analytical solution of $B({\xi})$, I could find out the characteristics of Submarine's turbulent wake for the given various ${\lambda}$, which were unknown facts before. As the results, $B({\xi}){\approx}{\frac{B({\xi})_{max}}{2}}$ and ${{\int}_{0}^{{\approx}0.6}}B({\xi})d{\xi}{\approx}0.85{{\int}_{0}^{1}}B({\xi})d{\xi}$ in the vicinity ${\xi}{\approx}0.6$, there was some dependencies on the given ${\lambda}$ though. The values of ${\lambda}$, in the range of $4{\leq}{\lambda}{\leq}8$, are more suitable to describe submarine's turbulent wake realistically, due to the bases on the quasi equilibrium state of turbulent wake. ${\lambda}$ mainly affects on the radius and detection range of the submarine's turbulent wake on the surface, however, the speed of submarine mainly affect on the duration of the wake rather than shape. If $7{\leq}{\lambda}{\leq}8$, it can be expected that the turbulent wake can be seen on the surface in the West sea, however, snorkeling(or snorkeled) submarine's wake can be found easily in the East sea.