• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.188-188
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• 2022

선박의 운용 효율을 높일 수 있는 방법인 무인 운용체계는 근래에 많은 관심을 받고 연구되어 왔다. 특히 무인수상선과 무인수중체의(USV-AUV)의 복합 운용 분야는 그 동안 어려움이 있었던 심해저 탐사 및 특수 임무 활용에 용이하여 많은 연구가 수행되고 있다. 본 연구에서는 쌍동선 형태인 무인수상선이 모선이 되고 무인수중체가 결합하여 충전하고 다시 진수하여 원거리 및 심해저 조건에서 무인수중체가 운용 가능하도록 하는 시스템의 일부인 USV-AUV의 docking을 위한 DP 시스템을 개발하고 선박해양플랜트연구소 해양공학수조에서 모형시험을 통해 이를 검증하였다. 또한, 실제 제작된 무인쌍동선과 추진 시스템을 활용하여 모형시험을 통해 검증한 DP 알고리즘을 적용하여 화성 제부도 앞바다에서 실선 DP 테스트를 수행하였다. 실 해역에서의 DP 시스템 테스트는 정확한 환경 조건의 계측 및 구현이 어려워 모형시험과 같은 정량적인 평가는 어렵지만, 정성적으로 DP 시스템이 작동하는 것을 확인할 수 있었다.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.268-277
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• 2022

In this study, each component of flow noise source of underwater propeller installed to the scale model of the KVLCC2 is investigated and the effect of each noise source on underwater-radiated noise is quantitatively analyzed. The computation domain is set to be the same as the test section of the large cavitation tunnel in the Korea Research Institute of Ship and Ocean Engineering. First, for the high-resolution computation of flow field which is noise source region, the incompressible multiphase Delayed Detached Eddy Simulation is performed. Based on flow simulation results, the Ffowcs Williams and Hawkings integral equation is used to predict underwater-radiated noise and its validity is confirmed through the comparison with the tunnel experiment result. For the quantitative comparison on the contribution of each noise source, the spectral levels of sound pressure and power levels predicted using propeller tip-vortex cavitation, blade surface and rudder surface as the integral region of noise sources are investigated. It is confirmed that the cavitation which is monopole noise source significantly contributed to the underwater-radiated noise than propeller blades and rudder which is dipole noise source, and the rudder have more contribution than propeller blades due to the influence of the propeller wake.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.331-334
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• 2009

An air-independent propulsion (AIP) system based on fuel cell technologies was developed for space and underwater applications in the present study. Hydrogen peroxide was selected as an oxidizer for space and underwater power applications where air independence is a must. Catalytic decomposition of hydrogen peroxide was used to generate oxygen and water. The pure oxygen was provided to a fuel cell and the water was stored separately. Sodium borohydride in the solid state was used as a hydrogen source in the present study. Pure hydrogen can be generated by a catalytic hydrolysis reaction. A fuel cell system was fabricated to validate the fuel cell based air-independent power system and was evaluated at the various conditions.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.3
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• pp.1-7
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• 2002

Flow mechanism of contractive and dilative motion is numerically investigated to obtain a propulsive force in highly viscous fluid, which is the simulation of the propulsion in micro-organisms. The computing code for the analysis of complicated motions is developed with cell-centered unstructured grid scheme. The developed code is validated by the well-known problems of cavity flow and oscillating wall. The validated code is applied to the contractive and dilative motion in narrow tube. The computed results are compared with nodal points scheme. By the present results, it is found that propulsive force can be obtained by the contractive and dilative motion through simulation with the developed code.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.464-464
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• 2023

최근 이산화탄소(Carbon Dioxode, CO₂) 배출량 증가로 인하여 지구온난화와 같은 기후변화 문제가 심각한 사회 문제로 대두되고 있다. 이에 따라 2015년 12월 12일 프랑스 파리에서 열린 제21차 유엔기후변화협약에서 교토의정서를 대체하는 파리협정(Paris Agreement)을 채택하였으며, 국내에서는 이러한 국제사회의 기후변화 대응에 동참하고 온실가스 감축을 이행하기 위한 2050 탄소중립 정책을 추진하였다. 이산화탄소를 다량으로 발생시키는 철강·산업·건설·에너지 분야 중건설 분야에서 배출되는 이산화탄소는 전체 배출량의 19.9%로 특히 시멘트를 제조하는 과정에서 많은 양의 이산화탄소가 배출되고 있다. 기존의 건설 분야 에서는 이산화탄소를 저감하기 위해 콘크리트 배합 또는 양생과정에서 챔버 내 이산화탄소를 가스 형태로 주입하여 탄산화 반응을 통해 콘크리트 내부에 이산화탄소를 영구히 저장시키고자 하였다. 그러나 이는 챔버 사용, 양생조건 등 적용 조건이 제한적이며, 콘크리트 내 이산화탄소 흡수 효율이 높지 않아 이를 개선할 수 있는 기술이 필요하다. 이를 개선하기 위해 최근에는 콘크리트 배합수 내 이산화탄소를 용해시켜 배합과정에서 콘크리트 내부로 이산화탄소를 강제로 인입시키는 연구들이 진행되고 있다. 그러나 콘크리트 배합수로 사용되고 있는 일반물이나 지하수의 경우 가압을 하여도 약 1,400mg/L의 이산화탄소를 용해시키며, 가압을 통해 용해된 이산화탄소는 쉽게 대기 중으로 방출되는 한계점을 지니고 있어 현장에서 사용하기 어려운 문제가 있다. 이러한 한계점을 극복하기 위해서 본 연구에서는 200nm 이하의 크기를 가지는 나노버블기술을 이용해 압력을 가하지 않은 상태에서 수중에 이산화탄소를 용해시킬 수 있는 시스템을 개발하고자 한다. 나노버블기술을 이용한 수중 이산화탄소용해 시스템을 통해 수중에 이산화탄소를 용해시켜 콘크리트 배합수로 활용하기 위한 기초 연구가 될 것으로 판단된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.451-454
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• 2011

Hydro-Reactive metal Fuel (HRF) which has more fuel than general solid propellant reducing oxidizing agent is suitable for ultrahigh speed rocket motor in the water. However, burning rate of HRF has not been studied yet. Through the earlier studies, we established ultrasonics measurement system measuring burning rate of solid propellant as a function of pressure in a single test and verified its reliability. In this paper, we will measure burning rate of HRF using ultrasound with previous development measurement system.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1103-1104
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• 2011

This paper presents 1kW BLDC motor drive system and magnetic coupler for water thrust in ROV. In order to get a high performance and reliability, some design flow is proposed in this paper. The proposed system is verified by the experimental tests.

• IE interfaces
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• v.11 no.2
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• pp.25-37
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• 1998

In this paper, a simulation model is proposed to evaluate the system effectiveness of underwater battery propulsion systems which consist of motors, main switchboard, generators and batteries. The various operating environments such as emergency situations, equipment's failure and repair, and system performance degradation due to equipment's failures affect the system effectiveness and the environment elements are considered as the input parameters in the simulation model. Some simulation results with estimated data are studied.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.27-40
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• 2013

This study is about development of technology system for an advanced deep-sea unmanned underwater robot of S. Korea analysed by the application of scenario planning. It was developed a 6000m class next-generation deep-sea unmanned underwater vehicle(or robot, UUV) system, soonly ROV 'Hemire' and Depressor 'Henuvy' in 2006 at S. Korea and motion control, adaptive control algolithm, a work-space manipulator control algolithm, especially the underwater inertial-acoustic navigation system robust to initial errors and sensor failures. But there are remained matters on position tracking of the USBL, inertial-acoustic navigation system, attitude sensor, designed sonar sensors. So this study suggest the new idea for settle the matters and then this idea help the development of the underwater inertial-acoustic navigation system robust to initial errors and sensor failures, such as acoustic signal drop-out, by modifying the error covariance of the failed sonar signal when drop-out occurs. As a result, the future policy for deep-sea unmanned underwater robot of S. Korea is to further spur the development of new technology and more improvement of the technology level for deep-sea unmanned underwater robot system with indicator and imaginary wall as external device.