• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.735-742
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• 2010

This paper reviewed the diving standards for underwater work in hostile environment and analyzed applied Navy diving technique, diving equipments and procedure for rescue operation of Navy ship Cheonan's missing crew occurred near Bak Ryung Do in March 2010. The operation was done beyond the international standards and safety practice, and by considering the nature of the mission, urgency and effectiveness as well as the detailed facts such as duration and depth of the dive, type of work to be performed, environmental conditions, time constraints of early rescue operation, it is analyzed that using air scuba diving system was adequate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.773-779
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• 2011

The width of a submarine's turbulent wake, using Shear-free and Ship wake theory, is proportional to $x^n,\;({\frac{1}{5}}{\leq}n<{\frac{1}{2}})$ If we assume submarine's length, width, velocity are 65m, 6.5m, 6kts respectively, and the minimum diffusion of turbulent wake ; ${\infty}\;x^{1/5}$, the width of wake behind the submarine is about 20m at 1.2km, 30m at 15km when there is no breaking waves on the sea surface. However, in the case of breaking waves, it is very limited to identify submarine's wake on the sea surface because wind generated turbulent wake has higher turbulent kinetic energy than that of submarine's wake. As a result, there is a high possibility to detect submarine's wake on the sea surface in the shallow water such as the Yellow-Sea using a proper detection method such as SAR. This means that in anti-submarine operations, non-acoustic sea surface serveillance applied turbulent wake will be very effective way to detect a submarine in near future. To do this we have to develop exact theory of submarine's turbulent wake above all.

• Journal of Navigation and Port Research
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• v.32 no.1
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• pp.109-114
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• 2008

This study is about the status and comparison of recreational scuba diving certification system in Southeast Asia countries. For the collection of the information, the contents of the numerous corresponding Internet sites were utilized, related documents were surveyed. And to supplement the information extensive interviews were held with the representatives of tourism department of many countries as well as staffs of diving associations, resort operators and diving instructors during various 2007 Dive Expos held in Southeast countries. In this paper, the relation between scuba certification and international standards were introduced for better understanding of the certification system. The research result shows that the scuba diving industry plays an important role in their country's tourism and the certification market of the Southeast Asia has grown to be greater than 30% of the world total market. However due to the facts that the scuba activity is originated from the western world and the controlling headquarters of the most certification agency are also located there, Southeast countries cannot take any leading roles in the scuba diving policies and systematic issues. Accordingly any modifications or improvements are expected to be very difficult. Also while Europeans and Americans have launched the programs and organizations for the quality assurance by cooperating with the international standards, but no such activity has yet appeared on the surface in Southeast Asia. According to the investigation the necessity will become bigger in near future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.790-797
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• 2015

This study tried to evaluate the safety and economical benefit of Nitrox-diving by comparing with Air diving. We used actual diving data which was recorded in construction site of the Busan-Geoje fixed link immersed tunnel in 2010. The study method was to assort and analyze the diving data by divers, depth, breathing air, and diving table. Furthermore, the study examined the possibility of outbreak decompression sickness by comparing Nitrox diving and Air diving in no-decompression limit time, decompression time, working time. As a result, this study confirms that if certain diver breathe Nitrox for diving and oxygen for decompression, not only the risk of decompression sickness could be minimized, but also duration of decompression could be shortened. Moreover, it was estimated that a remarkable difference(more than 3 times) between actual duration of underwater construction period and virtual construction period by using air. As a result, the study confirmed that Nitrox diving is more efficient and economical than Air diving in physically limited and hazardous diving environment.

• Proceedings of the ESK Conference
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• 1998.04a
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• pp.131-136
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• 1998

2개의 simulated된 잠수 실험 즉, 심도 19 ATA와 24 ATA의 고압 Heliox 환경하에서, 4명의 다이 버를 대상으로 하여연 188일간 매일 23:00부터 익일7:00시 사이에 각 다이버에대해서 표준적인 polysomnography를 기록했다. 2개의 잠수조건 하에서 양 실험 모두 해저에서 체재하는 동안 의 밤과 감압하는 동안의 밤 동안에는 총수면시간 (Total Sleep Time)의 단축, 수면효율(Sleep Efficiency)의 감소, 입면잠시(Sleep Latency)의 연장, 중도각성회수 (Number of Awakeningss) 와 감소를 보였지만, 어느쪽도 뚜려한 변화가 있었다라고는 할 수 없었다. 24 ATA 잠수조건에서 의 해저에서 체재하는 동안의 밤과 감압하는 동안의 밤 동안에서는 19 ATA 잠수조건에 비해서 4 단계수면(stage 4 sleep )만 유의한 감소를 보였다. 2개의잠수조건 모두 잠수기간 중에 있어서 는 각성하기 쉬운 상황이었으며, 기본적인 수면패턴에 있어서는 큰 변화는 보이지 않았다.

• Defense and Technology
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• no.8 s.234
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• pp.76-85
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• 1998

잠수함은 언제, 어디에서, 어떻게 나타날지 모르는 바다의 게릴라이기 때문에 상대국가에게 해상전력의 상당부분뿐만 아니라 지상전력의 일부까지도 대 잠수함 정찰/감시 임무에 투입하도록 하는 매우 중요한 전략적 가치를 갖는다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.176-183
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• 2020

A ship has three types of diving systems (Diver Stage Diving, Wet Bell Diving and Scuba Diving) to carry out a search-and-rescue operation. To reduce the possibility of decompression sickness, any diving systems shall comply with the decompression procedure according to the decompression table corresponding to the diving depth and diving time. The decompression procedure is largely divided into two methods: underwater decompression and underwater-onboard decompression. In particular, the surface interval shall not exceed 5 minutes, which is the phase from underwater decompression to underwater-onboard decompression, in accordance with the U.S Navy Diving Manual. However, the surface interval is greater than 5 minutes as a result of using Wet Bell Diving. This paper describes the result of cause analysis and measurement with improved Wet Bell Diving. Using improved Wet Bell Diving reduced the surface interval to less than 5 minutes. The result of the research can be used for operation and improving the performance of diving systems.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.9-16
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• 2015

This research focuses on analysis of the flight trajectory characteristics of SLBM (Submarine Launched Ballistic Missile) of North Korea. Recently, North Korea tested launching of SLBM which is threatening international security. Also it is known that North Korea had possessed the technologies about SLBM since they disassembled submarines out of commission of the former Soviet Union. If the development of the SLBM of North Korea is completed, it should be affected as asymmetric threat to South Korea. Therefore, for active respondence to these threat, it is essential to analyze the SLBM systematically. In this point of view, this work made a SLBM flight model and simulated. In addition, we controled flight trajectories according to adjusting loft angle and described their characteristics. The sea-based ballistic missile defense system is required for an effective response to the flight trajectory of the SLBM from mid-course to terminal phase.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.107-116
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• 2001

Any small leakages in the submarines could lead to the serious consecutive damages since it operates under high water pressure. Such leakages including damages of pipe and hull itself eventually could incur humane casualties and loss of expensive properties as well as the loss of combat capabilities. In this paper, knowledge based decision system is developed. The domain knowledge is acquired from document of submarine design, design expertise and interview with operator. Damages of hull itself and pipes are treated and decision is recommended whether to stay in the sea or to be blowing, for instance.

• Journal of Preventive Medicine and Public Health
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• v.31 no.1 s.60
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• pp.139-156
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• 1998

Diving related disease including decompression sickness is an important occupational health problem and diving fishermen remain a fairly hazardous occupation in Korea. To prevent diving related disease, we investigate diving patterns, incidence of diving related diseases, and contributing factors of 433 diving fishermen of three coast interviewing and mailing questionnaire in 1996. Mean age of divers was 39.7 years, ranged from 24 to 58 years, 92.8% of these were male, and 58.4% of divers were high school graduates. Mean duration of work as a diver was 12.9 years, ranged from 2 to 40 years. It was found that 70.4% of divers were using hookah system, 22.2% of helmet, and only 2.5% SCUBA. About half of them have learned diving skills from other divers. The peak season of diving was from April to June and mean working days were 20.3 days per month during the peak season. On the average, the divers dived 5-6 times, ranged from 1 to 10 times a day with 51.1 minutes of diving time, ranged from 20 to 120 minutes, at 30 m or 40 m in depth, and 35.5 minute of interval on surface. Most divers ascended slowly making decompression stop, yet the decompression profile used was not based on any scientific knowledge except for their own experiences. It appeared that each diving system had slightly different diving patterns. There were 282(65.0%) divers that suffered from DCS in 1995 and 31.2% of divers were given recompression therapy at a medical facility since they worked as diving fishermen. Skin and musculoskeletal complaints were common symptoms of DCS and 39% of divers experienced a voiding difficulty. In univariate analysis, females have an increased frequency of DCS(93% vs 66% for males). Old age, long duration of work, helmet diving, diving time, diving depth, repetitive diving, and blow up were all contributing factors to DCS. It was found that most diving patterns exceed no decompression limit and did not use the standard decompression table. This suggests that most of divers are at high risk of developing diving related disease with prolonged dives and lengthy repetitive diving in deep depth. Considering the diving patterns and economic aspect of professional diving, the incidence of DCS among diving fishermen in Korea will not decrease in the near future. These findings suggest that periodical health surveillance for divers, and education of health and safety are important for reducing the risk of diving related disease in the population of diving fishermen.