• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.640-647
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• 2018

Many harbor structures have been constructed, and some structures are now under construction in Korea, which is a peninsular state and a logistics hub in Northeast Asia. Expansions and extensions of existing harbors are also being planned to meet increasing natural disaster threats. Wave-dissipation concrete blocks are recycled or discarded based on the personal experience of engineers only, and there are no safety checks or criteria. To check the safety of used blocks, material evaluations were done by visual inspection of blocks on the ground and under water and from 20 non-destructive measurements of the rebound hardness test and 3 concrete core samples. Wave-dissipation blocks are sometimes fully or partially damaged in the process of transferring and mounting them or during construction. Therefore, a safety check is essential for recycling blocks with an evaluation of materials while considering the construction phases. To do this, a block was modeled with a 3D finite element method using ADINA, and impact analyses were done according to the transfer, mounting, and construction phases. From the results of the impact analyses and material evaluation, the safety checks and reasonable evaluation of used blocks were examined, and detailed construction methods are proposed. The methods are expected to maximize the reuse of used wave-dissipation blocks from an economical point of view.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.1
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• pp.41-48
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• 1993

Using the eight-year-working diaries($1984{\sim}1991$) of the fishing co-operative in Tonggui-ri, Cheju-do, as well as the records of consignment sale in the fish trust market as the corporate body in Aewol-up, the results have been analyzed as follows. 1. The monthly catch of Turbo cornutus was high from September through December, representing $58.2\%$ of the annual total catches. The maximum sustained yield(MSY) of this stock was estimated to be 2.5 tons. 2. The maximum sustained yields of Haliotis spp. and Sulculus sp. were estimated to be 800kg and 750kg, respectively. 3. The maximum sustained yields of Stichopus sp. and Octopus sp. were 500kg and 2, 500kg, respectively. 4. The total yield of Hizikia fusiforme has been decreasing a little and that of Gelidium sp. has been increasing. The total yield of Gelidium sp. in 1984 was about 5 times greater than that in 1990. 5. The daily catchability by divers have been high at thirties, and the individual mean working day of divers was 101 per year. 6. The consignment sale rates were $100\%$ each for Turbo cornutus, Hiziki fusiforme and Gelidium sp., $25.5\%$ and $61.1\%$ for Haliotis sp. and Stichopus sp. respectively, and $0\%$ each for Sulculus sp. and Octopus sp.

• Strategy21
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• s.42
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• pp.5-52
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• 2017

Debates about introducing nuclear submarines have been a main issue in Korea. The highest officials and the government has started to think seriously about the issue. Yet there were no certain decision to this issue or any agreements with US but it is still necessary to review about introducing nuclear submarines, the technologies and about the business. The reason for such issues are the highest officials of Korea to build nuclear submarine, nK's nuclear development and SLBM launching. ROKN's nuclear submarine's necessity will be to attack(capacity to revenge), defend(anti-SSBN Operation) and to respond against neighboring nation's threat(Russia, Japan, China). Among these nations, US, Russia (Soviet Union), Britain, France had built their submarines in a short term of time due to their industrial foundation regarding with nuclear propulsion submarines. However China and India have started their business without their industrial foundation prepared and took a long time to build their submarines. Current technology level of Korea have reached almost up to US, Russia, Britain and France when they first built their nuclear propulsion submarines since we have almost completed the business for the Changbogo-I,II and almost up to complete building the Changbogo-III which Korea have self designed/developed. Furthermore Korea have reached the level where we can self design large nuclear reactors and the integrated SMART reactor which we can call ourselves a nation with worldwide technologies. If introducing the nuclear submarine to the Korea gets decided, first of all we would have to review the technological problems and also introduce the foreign technologies when needed. The methods for the introduction will be developments after loans from the foreign, productions with technological cooperations, and individual production. The most significant thing will be that changes are continuous and new instances are keep showing up so that it is important to only have a simple reference to a current instances and have a review on every methods with many possibilities. Also developing all of the technologies for the nuclear propulsion submarines may be not possible and give financial damages so there may be a need to partially introduce foreign technologies. For the introduction of nuclear propulsion submarines, there must be a resolution of the international regulations together with the international/domestics resistances and the technological problems to work out for. Also there may be problem for the requirement fees to solve for and other tough problems to solve for. However nuclear submarines are powerful weapon system to risk everything above. This is an international/domestically a serious agenda. Therefore rather than having debates based on false facts, there must be a need to have an investigations and debates regarding the nation's benefits and national security.

• Strategy21
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• s.42
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• pp.318-346
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• 2017

Currently, security environmental instability is getting worse than ever in the East Asia including to Republic of Korea(ROK). Unlike several conventional issues such as maritime dispute -sometimes with islands- and competitions for getting natural resources, contemporary security dilemma issues followed by arms races among states deepens the power gap between strong and weak state within the region. It is notable that the arms races is the East Asia are mainly focused on naval power. As navy is the very possible force that influences neighboring states, submarine power is usually valued for its nature of stealth, mobile and aggression. Moreover, the submarine power is believed to be one of the highest valued weapon system since it shows actual effectiveness for influencing the other states while avoiding direct military conflicts compared to surface power. As a result, all states within the region are accelerating for getting such power these days. Japan, Most of all, is one of the leading state that aims to ensure self-survival and enlarge military influences under the US-Japan alliance by decisively supporting its power to the American containment strategy against China. In this regard, such movement surely sill influence on ROK both directly and indirectly as we sue the common field, the sea. Though, it has lots of restrictions for us to confront them with military forces as such confrontations within US-led alliances is not desirable upon considering current China and nK threats. As a result, ROK needs to limit the realm of alliance within the region while maintaining ROK-US alliance for getting national interests with both legal and justice superiority against Japan. This paper, as a result, is focused on suggesting the way to utilize submarines as a mean of naval power for both current security environments and the rising maritime threats in the East Asia. I concluded to participate ROK submarines in US-led military strategy against China by dispatching them into the East-China Sea and the North-East area of the Korean peninsula to protect both national interests and justice at the same tome. It should be one of the preemptive measure for confronting with neighboring states by utilizing strategic benefits of submarines while strengthening ROK-US alliances upon participating American Containment Strategy against China.

• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.548-549
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• 2015

무인 잠수정은 자율 무인잠수정(이하 'AUV' 또는 '자율무인잠수정'을 혼용)과 원격조정잠수정(이하 'ROV'로 지칭)으로 분류를 할 수 있다. ROV는 테더 게이블로 인한 작업 범위의 한계와 운동성능 효율이 떨어지는 단점을 지니고 있어, 테더 케이블이 필요 없는 AUV에 대한 필요성이 증대되고 있다. 추측 항법 시스템인 관성 항법 시스템(inertial navigation system, 이하 'INS'로 지칭)은 외부 도움없이 관성측정 장치(inertial measurement unit, 이하 'IMU'로 지칭)를 활용하여 구성된 시스템을 말한다. IMU는 자이로 스코프(gyroscope), 가속도계(accelerometer), 지자기(magnetic)센서로 구성된 측정 장치로 3개의 센서를 사용하여 상호 보정을 통한 기동 체의 위치, 속도 및 자세 정보를 제공한다. 복합항법시스템은 추측항법시스템이 가지는 누적오차와 측위 항법시스템이 가지는 외부환경에 대한 단점을 상호 보완하는 방법으로 연구가 진행 중이다. 하지만 심해서 또는 해양의 특성에 따라 측위 시스템이 사용되지 못하기 때문에 추측 항법시스템의 다양한 관성 센서를 활용한 상로 보완과 신호처리 방법을 통한 연구 개발이 진행 중이다. 다양한 센서 정보를 통합하는 목적으로 칼만 필터와 같은 최적 필터기법이 보편적으로 사용되고 있다. 칼만 필터는 확률 선형 시스템에 대하여 공정잡음 및 측정 잡음이 가우시안 확률 분포를 따를 때 최적의 추정자가 된다. 또한 가우시안 조건을 만족하지 않는 경우에도 선형 추정자 중에 추정 오차의 분산이 가장 작은 추정자이다. 칼만 필터가 최상의 성능을 발휘 하려면 공정잡음과 측정 잡음의 실제 값을 정확히 알아내는 것이 중요하다. 잡음 수준에 대한 정보가 부정확 할 경우 칼만 필터는 발산 할 수 있기 때문에 시스템에서 잡음 수준의 공산은 칼만 필터의 최적 이득을 결정하는 중요한 요소로 추정치에 큰 영향을 준다. 따라서 칼만 필터를 추측항법시스템에 적용 시킬 경우 실제 모텔의 잡음 공분산을 정확히 추정할 수 있는 기법이 요구된다. 추측항법시스템은 다양한 센서를 활용하기 때문에 움직이는 기동 표적에 적용시 잡음공분상이 변하기 때문에 항법시스템이 저하 될 수 있다. 본 연구에서는 다양한 센서를 융합하여 해양 생체 로봇의 정밀 자세 제어가 가능한 시스템을 제안하고자 한다.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.747-761
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• 2008

In order to experiment the acoustic remote classification of seabed sediment, we achieved ground-truth data(i.e. video and grab samples, etc.) and developed post-processing for automatic classification procedure on the basis of 300 kHz MultiBeam Echo Sounder(MBES) backscattering data, which was acquired using KONGBERG Simrad EM3000 at Sock-Cho Port, East Sea of South Korea. Sonar signal and its classification performance were identified with geo-referenced video imagery with the aid of GIS (Geographic Information System). The depth range of research site was from 5 m to 22.7 m, and the backscattering amplitude showed from -36dB to -15dB. The mean grain sizes of sediment from equi-distanced sampling site(50 m interval) varied from 2.86$(\phi)$ to 0.88(\phi). To acquire the main feature for the seabed classification from backscattering amplitude of MBES, we evaluated the correlation factors between the backscattering amplitude and properties of sediment samples. The performance of seabed remote classification proposed was evaluated with comparing the correlation of human expert segmentation to automatic algorithm results. The cross-model perception error ratio on automatic classification algorithm shows 8.95% at rocky bottoms, and 2.06% at the area representing low mean grain size.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.3
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• pp.181-187
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• 2009

To estimate the status and volume of artificial reefs(ARs) deployed at the sea bottom in fishing grounds, this study assessed the initial volume of ARs, the cubic volume of AR groups, and the porosity of each AR using image data collected during a survey using a multi-beam echo sounder(MBES) and a side scan sonar(SSS). These results were compared with data collected during diver surveys and used to develop a new method and prediction formulas for countermeasures, facility volume, and efficient use of volume for deployed ARs(cubic concrete). The field survey results for nine ARs deployed in the Busan Sea region were calculated, and the average value of coefficient k(indicating the efficient use of volume ratio) among ARs was 0.753, and the correlation between coefficient k and year(Yr) of deployment was calculated as k=0.0023Yr+0.725. The relationship between these two factors was poor. In years following the deployment of artificial reefs, coefficient k and year of deployment were not correlated, in spite of the hardening ground due to subsidence and the reduced distance between ARs. Consequently, it is reasonable to suppose that coefficient k was defined by bottom surface conditions and initial deployment conditions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.3
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• pp.179-187
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• 1977

This study intended to investigate the shape of the artificial fish reefs settled in the waters of Seogwipo, and the thronging of fish schools into them. The results obtained are summarized as follows : 1. Two types of artifical fish reef, circularized vertical type which is composed of Cryptomeria branches and parachute type, were put off the coast of Seogwipo at $33^{\circ}14'05'$ N Lat., $126^{\circ}34'40'$ E Long. The setting place is located 0.4 sea-mile away from natural fish reefs, at 25 m in depth. And its sediment is consisted of f. S. and Sh. 2. Maximum velocity of wind drift current was 15.28 cm/sec at 15 m depth. The Current direction was $20.5\%$n in the WSW. 3. Maximum fluid resistance of the circularized vertical type to current and wind waves showed about 890 kg, and the weight of sand bags attached to the fish reef totaling 1,200 kg was enough to sustain fish reef. 4. As maximum fluid resistance of the parachute type to current and wind waves was 106.3 kg, the retaining force of sand bags was enough to sustain the fish reef, but vinyl canvas and expansion materials were so poor that the fish reef was lost by the sea current and wind waves. 5. Sixteen species of fish among 53 usually caught in this area were thronged into the artificial fish reef. The fish catches comprized Porgy (Pagrosomus major) $23\%$, black kook fish (Sebastes (Mebarus) intermis) $13\%$, sand borer (Sillago sihama) $11\%$, Sebastes (Pteropodus) hubbsi $7\%$, and file fish (Monacanthus cirrhifer) $6\%$. According to the submarine observations by fivers, it was confirmed that a lot of fish larvae thronged in the middle part of the fish reefs.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.433-439
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• 2020

This study compared and analyzed the change of air consumption according to water depth with human characteristics and theoretical values. The experimental results are as follows. First, subjects A and B showed similar rise rates depending on the water depth. Second, subject C had a significantly higher rate of increase in air consumption at 25m underwater because the body responded sensitively to deep water pressure, which increased air consumption because breathing was faster than other participants. Third, the subjects D and E showed significantly lower overall air consumption. D and E were 37 and 35 years of age, respectively, the youngest, strongest and most experienced in deep sea diving at the time of military service. Fourth, the average air consumption per minute of the test subjects increased from 5m in water to 1.45 times, 10m in water to 1.85 times, and 20m in water to 2.8 times. This seems to be a result of different experiences, physical fitness, the degree of adaptation of the body to underwater, and different breathing techniques. Lastly, the difference between the experimental average value and the theoretical value appears to be the result of using more or less air than the theoretical value depending on the experiences and physical strength of each of the 5 rescuers, the degree of adaptation of the body underwater, and the method of underwater breathing.