• 한국해양공학회지
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• 제6권2호
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• pp.113-124
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• 1992

The offshore industry created a need for quality wet weld repairs. Wet welding is a fast method of repair providing sound, structural quality welds. It requires less support equipment than a similar underwater dry weld repair or the alternative mechanical connections. Compared to welds made in air, underwater wet welds are plagued by increased hardness due to rapid quenching by the surrounding water. In this paper is described the experimntal study of improving the cooling rates of wet welds of TMCP steel plate by shielding around weld arc surroundings. The principal results of this experimental investigation can be summarized as follows : By shielding around weld arc surrounding, the cooling rates resulting from wet welds on TMCP steel plate could be lower than that of nonshielded wet welds and the fesibility on high quality of mecanical properties of wet weld on TMCP steel plate was carried out with shielded weld arc surrounding.

• 한국항해항만학회지
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• 제45권1호
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• pp.16-25
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• 2021

동유체력 미계수는 수중운동체의 조종성능을 예측하기 위해 정확히 추정되어져야 하며 추정 방법의 일환으로 다양한 모형시험이 수행되어오고 있다. 수중운동체는 횡동요 모멘트 변화에 민감하므로 관련 동유체력 미계수를 추정하는 작업은 정확히 수행되어져야 한다. 본 연구에서는 횡동요 운동과 관련한 동유체력 미계수를 간단하게 추정할 수 있는 순수 횡동요 장비를 새롭게 설계하였다. 횡동요 운동은 간단한 기계적 메커니즘을 통하여 구현하였으며, 메커니즘의 원리와 적용과정 그리고 설계한 장비의 system identification에 대해 기술하였다. 또한 순수 횡동요 시험의 해석방법을 제시하고 설계한 장비에 대해 반복시험을 거쳐 결과의 재현성을 확인하였다.

• 한국산학기술학회논문지
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• 제16권12호
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• pp.8889-8895
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• 2015

수중 기초사석 고르기 작업이나 수중시설물 점검 및 유지관리 등 수중 항만 공사를 위해서 수중에서의 충분한 시계확보가 필수적이다. 이는 잠수사에 의한 작업뿐만 아니라 수중 기계화 장비를 활용한 작업에서도 마찬가지다. 본 연구에서는 우리나라 동해, 남해, 서해에서 대표적인 항만이 위치하는 연근해 해역의 탁도를 측정하여 권역별 경향성을 수치적으로 확인하였다. 또한, 다양한 탁도 특성을 가지는 각 해역에서 수중 카메라나 소나 등과 같이 수중건설장비에 부착하여 효과적으로 활용 가능한 수중환경모니터링 시스템에 대해 검토하였다.

• Journal of Welding and Joining
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• 제10권2호
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• pp.51-62
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• 1992

A torch was designed and fabricated in order to develope the technology of "locally drying underwater welding" by water curtain method. The condition for the formation of the possible local cavity, the mechanical properties and the thermal cycle of welds were investigated in the developed welding equipment compared with in-air welding. The possibility of highly reliable and practical underwater welding was found. The proper local cavity was formed above the water flowrate of 30l/min and CO$_{2}$ gas flowrate of 100l/min. The bead width and penetration depth were increased with increasing welding current. The hardness of weldments is about 160Hv in air welding, but about 210Hv in underwater welding. The elongation and the impact value of underwater weldments are 15% and 6Kg/cm$^{2}$ respectively, which are only half as much as the values of in-air welding. The cooling time in the temperature range from 800.deg.C to 500.deg.C affecting the structure and the hardness of weldments is about 22sec. in air welding while about 10sec. in underwater welding.r welding.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.274-284
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• 2019

The control architectures of Chuan Suo (CS) deep submergence rescue vehicle are introduced. The hardware and software architectures are also discussed. The hardware part adopts a distributed control system composed of surface and underwater nodes. A computer is used as a surface control machine. Underwater equipment is based on a multi-board-embedded industrial computer with PC104 BUS, which contains IO, A/D, D/A, eight-channel serial, and power boards. The hardware and software parts complete data transmission through optical fibers. The software part involves an IPC of embedded Vxworks real-time operating system, upon which the operation of I/O, A/D, and D/A boards and serial ports is based on; this setup improves the real-time manipulation. The information flow is controlled by the software part, and the thrust distribution is introduced. A submergence vehicle heeling control method based on ballast water tank regulation is introduced to meet the special heeling requirements of the submergence rescue vehicle during docking. Finally, the feasibility and reliability of the entire system are verified by a pool test.

• 해양환경안전학회지
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• 제26권1호
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• pp.47-56
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• 2020

본 연구는 국내외 수중레저활동 관련 법률을 분석하여 국내 수중레저법에 대한 개선방안을 다음과 같이 제안한다. 첫째, 수중레저활동자는 '수중레저사업자로부터 계약을 통해 수중레저활동 서비스를 제공받으며 수중레저활동을 하는 사람'으로 개정되어야 한다. 둘째, 수중레저활동구역을 설치하는 주체는 '수중레저사업자 및 수중레저활동자 등'으로 확대되어야 한다. 셋째, 레저 테크니컬 다이빙은 나이트록스 또는 혼합 가스 등을 사용하므로 가스 종류가 명확히 기재된 스티커 또는 밴드를 부착하도록 규제가 추가되어야 한다. 넷째, 다이빙 필수 장비에 수면표시부표(SMB)를 추가하고 공기통에 대한 일상 관리 및 정비방법에 대한 규제조항이 추가되어야 한다. 다섯째, 수중레저활동자의 다이빙 보험가입을 적극 권유하도록 제도화 할 필요가 있다. 이외에도 수중레저활동자의 안전을 확보하기 위해 수중레저사업자의 응급절차와 다이빙 가이드라인을 구체적으로 명시할 필요가 있다.

• 대한조선학회논문집
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• 제57권6호
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• pp.322-330
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• 2020

This study deals with underwater explosion (UNDEX) characteristics of various non-explosive underwater shock sources for the development of non-explosive underwater shock testing devices. UNDEX can neutralize ships' structure and the equipment onboard causing serious damage to combat and survivability. The shock proof performance of naval ships has been for a long time studied through simulations, but full-scale Live Fire Test and Evaluation (LFT&E) using real explosives have been limited due to the high risk and cost. For this reason, many researches have been tried to develop full scale ship shock tests without using actual explosives. In this study, experiments were conducted to find the characteristics of the underwater shock waves from actual explosive and non-explosive shock sources such as the airbag inflators and Vaporizing Foil Actuator (VFA). In order to derive the empirical equation for the maximum pressure value of the underwater shock wave generated by the non-explosive impact source, repeated experiments were conducted according to the number and distance. In addition, a Shock Response Spectrum (SRS) technique, which is a frequency-based function, was used to compare the response of floating bodies generated by underwater shock waves from each explosion source. In order to compare the magnitude of the underwater shock waves generated by each explosion source, Keel Shock Factor (KSF), which is a measure for estimating the amount of shock experienced by a naval ship from an underwater explosionan, was used.

• 한국수산과학회지
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• 제23권6호
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• pp.451-456
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• 1990

Underwater acoustic navigation and position fixing systems have been extensively used not only in surface position fixing but also in underwater position fixing. Tn recently, application of these systems has been in the field of underwater inspection of offshore platforms, where it is vital to track the position of an unmanned submersible or diver carrying underwater cameras and nondestructive testing equipment. But these systems are included the fixing errors as results of a signal with additive noise, the attenuation of sound and the interference effects due to multipath reflection and forward scattering. In this paper to improve the position fixing by the supershort baseline acoustic position system, a method to apply the Kalman filter to the fix of the system is proposed and the digital simulation under noise condition is conducted. The optimal positions by the Kalman filter are compared with original positions, and it is confirmed that the results of the pro-posed method are evidently more accurate.

• 제어로봇시스템학회논문지
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• 제19권9호
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• pp.760-767
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• 2013

In this paper, we developed a Manta-type AUV (Autonomous Underwater Vehicle) and analyzed its control performance as well as its dynamic characteristics underwater. The nonlinear motion of equations, which are expressed in terms of hydrodynamic coefficients obtained by various experiments, are used to simulate the motion of a Manta AUV underwater. We applied the sliding-mode theory to control the heading angle and depth of the vehicle, and confirmed the effectiveness of the control algorithm through simulations and sea-trials.

• Ocean Systems Engineering
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• 제1권2호
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• pp.111-119
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• 2011

Mines, torpedoes and improvised explosive devices (IED) pose a serious threat to the survivability of naval combatants. Inasmuch, a major goal in the design of modern combatant ships has been to eliminate or at least reduce the devastating damage caused by underwater explosion events. Even though there has been extensive research performed on the various underwater explosion phenomena and their associated effects, effective shock testing and shock proofing strategies for naval ship systems have proven to be illusive. Through the use of modeling and simulation (M&S), live fire test and evaluation (LFT&E) and laboratory testing, general guidelines for the shock hardening of shipboard equipment and systems have been developed. In this paper, current aspect of ship survivability has been addressed and future direction is discussed.