• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.316-320
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• 2003

This paper introduces an autonomous underwater vehicle (AUV) model, ASUM, equipped with a visual servo control system to dock into an underwater station with a camera and motion sensors. To make a visual servoing AUV, this paper implemented the visual servo control system designed with an augmented state equation, which was composed of the optical flow model of a camera and the equation of the AUV's motion. The system design and the hardware configuration of ASUM are presented in this paper. ASUM recognizes the target position by processing the captured image for the lights, which are installed around the end of the cone-type entrance of the duct. Unfortunately, experiments are not yet conducted when we write this article. The authors will present the results for the AUV docking test.

• 한국세라믹학회지
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• 제39권10호
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• pp.963-969
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• 2002

본 연구에서는 수중불분리혼화제로서 메칠셀룰로스계를 사용하였고 자체 개발한 멜라민유동화제의 수중불분리콘크리트에 대한 사용량을 5, 7, 9, 11 kg/$m^3$으로 첨가량을 달리하여 slump folw, flow loss, 응결사간, 탁도 및 pH, 압축강도, 수중/기중 압축강도비를 실험한 결과 수중불분리콘크리트의 물성이나 경제성등을 고려할 때 수중불분리콘크리트에서의 멜라민유동화제의 사용량은 약 9 kg/$m^3$인 것으로 나타났다.

• 제어로봇시스템학회논문지
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• 제15권6호
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• pp.567-572
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• 2009

The underwater launch system using an ATP consists of five parts: compressor tank, proportional flow control servo valve, expulsion spool valve, air turbine pump, and discharge tube. The purpose of this study is to develop an underwater launch system using an ATP and to verify the validity of the system. The proportional flow control servo valve is modeled as a 2nd order transfer function. The projectile is ejected by pressurized water through the air turbine pump, which is controlled by expulsion valve. The mathematical model is derived to estimate the dynamic characteristics of the system, and the important design parameters are derived by using simulations. The computer simulation results show the dynamic characteristics and the possibility of control for underwater launch system.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.165-170
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• 2000

A fundamental experimental study for a substitute proposal to super-speed craft propulsion system called underwater ram-jet propulsion by high pressure air ejection as driving force was investigated. for basic study of effect of ram-jet propulsion performances ismple underwater ram-jet flow field was established and PIV(Particle Image Velocimetry) method was adopted to analyse the jet-induced flow appearing at ram intake mixing chamber and nozzle. Some flow dynamics relating to the high-speed ejector effect were discussed for the basic understanding for the ram-jet propulsion principle.

• Journal of Advanced Marine Engineering and Technology
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• 제24권3호
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• pp.36-42
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• 2000

A fundamental experimental study for an alternative proposal to super-speed craft propulsion system called underwater ram-jet propulsion by high pressure air ejection as driving force was investigated. For basic study of the effects of ram-jet propulsion performance, a simple underwater ram-jet flow field was established and PIV(Particle Image Velocimetry) method was adopted to analyse the jet-induced flow appearing at ram intake, mixing chamber and nozzle. Some flow dynamics relating to the high-speed ram-jet effect were discussed for the basic understanding of the its propulsion principle.

• 한국소음진동공학회논문집
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• 제16권2호
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• pp.190-197
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• 2006

It is well known that the acoustic characteristics of the sea are significantly affected by bubbles which have their own inherent characteristics at the undersea. In this study, the shape and acoustic characteristics of air bubbles generated by an underwater nozzle are calculated numerically, and are measured with a high speed camera and a hydrophone at various air flow rates in the experimental apparatus. As a result of analysis, the shape calculated numerically well matched with measured values at low flow rates, but in case of relatively higher flow rates. the use of correction coefficient is needed for more accurate estimation of the bubble shape. And also the rising velocity of a single bubble is constant regardless of both the bubble size and the flow rate. and the acoustic signal generated when the bubble is produced by an underwater nozzle has the same characteristic of natural frequency of the bubble pulsation, and is agreed with Minnaert's equation if the correction coefficient is considered in accordance with the flow rate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.609-612
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• 1999

Recently, the antiwashout underwater concrete with an antiwashout admixtures has been increasingly used for underwater structures. However, the credibility of antiwashout underwater concrete was brought up as problems because it seldom was applied to fields. In this study, experiments were made on the basic properties of antiwashout underwater concrete replaced with fly ash up to 30% to improve its properties. Resultant to the test, we got the results as follow; funnel flow time was decreased, the slump flow was increased and the elevation of head was decreased rapidly whereas the amount of suspended solids became high, pH became low. In view of 70%, the standard ratio of compressive strengths between cast in water and in air, it was obtained the result that the ratio was over 90% at 28days.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.109.5-109
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• 2002

Autonomous underwater vehicles (AUVs) are unmanned underwater vessels to investigate sea environments, oceanography and deep-sea resources autonomously. Docking systems are required to increase the capability of the AUVs to recharge the batteries and to transmit data in real time in underwater. This paper presents a visual servo control system for an AUV to dock into an underwater station with a camera. To make the visual servo control system , this paper derives an optical flow model of a camera mounted on an AUV, where a CCD camera is installed at the nose center of the AUV to monitor the docking condition. This paper combines the optical flow equation of the camera with the AUV's equation o...

• 한국세라믹학회지
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• 제39권10호
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• pp.970-976
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• 2002

본 논문에서는 수중불분리혼화제와 수중불분리혼화제+방청제를 병용(1 type)한 혼화제를 사용하여 콘크리트의 slump flow, 탁도, pH, 방청효과, 블리딩, 압축강도의 특성을 분석하였다. 그 결과 slump flow, 탁도, pH, 압축강도등 콘크리트의 물리적인 특성에서는 차이가 없었으나 부식촉진서험결과 수중불분리혼화제만을 사용한 콘크리트와 방청제를 병용(1 type)하여 사용한 것의 방청율이 큰 차이를 나타내었으며, 수중불분리혼화제만을 사용하였을 경우 5.4, 방청제와 병용하여 사용하였을 경우 0.07%로 방청제를 병용(1 type)하여 사용한 큰크리트의 내부식성이 높게 나타났다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권1호
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• pp.55-65
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• 2017

Underwater torpedo has control fin with very low aspect ratio due to launching from limited size of cylindrical torpedo tube. If the aspect ratio of control fin of underwater vehicle is very low three-dimensional flow around control fin largely reduces control forces. In this study, the end plate was applied to reduce the three-dimensional flow effects of partially movable control fin of underwater vehicle. Through numerical simulations the flow field around control fin was examined with and without end plate for different flap angles. The pressure, vorticity, lift and torque on the control fin were analyzed and compared to experiments. The comparison have shown a reasonable agreement between numerical and experimental results and the effect of end plate on a low aspect ratio control fin. When the end plate was attached to the movable control fin, the lift increased and the actuator shaft torque did not significantly change. As this means less consumption of the actuator shaft torque compared to the control fin that has the same control force, the inner actuator capacity can be reduced and energy consumption can be saved. Considering this, it is expected to be effectively applied to the control fin design of underwater vehicles such as torpedoes.