• 대한기계학회논문집A
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• 제20권1호
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• pp.24-34
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• 1996

In ordaer to hold an underwater vehicle at a certain depth, buoyancy that acts on the underwater vehicle can be modulated. In this research, buoyancy that could control depth of underwater vehicle is generated by a buoyancy bag. Solenoid valves are operated by pulse with modulation(PWM) method. State equation, in consideration of the volume of buoyancy bag, pressure inside bag, and dynamic of the underwater vehicle, is derived. This system is very unstable, inculdes modelling error and nonlinearity. In depth control system, maintanance of performance is required., anainst vatiation of systerm parameter and operating depth, and designed. Through the computer simulation, performance is comparerd for each controllers.

• 한국재난관리표준학회지
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• 제3권2호
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• pp.33-39
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• 2010

본 연구는 부력가방의 익사사고 저감성능 분석에 관한 연구로서, 시민들은 레저 활동 및 물놀이 활동 시 부주의로 인하여 익사사고가 발생할 경우 119구조대나 타인의 구조활동만으로는 사고자 생존율이 저조하다고 할 수 있다. 이에 따라 수상 전문가들은 부력제품을 활용하여 익사사고를 줄이고, 시민은 일상용 휴대가방에 안전관리 기능을 추가한 부력가방을 평상시에 차량안이나 개인이 직접 휴대함으로써 본인의 생명과 위급한 상황에 봉착한 타인을 신속하게 구조할 수 있는 구명용 도구로 활용할 수 있도록 하였다. 본 연구를 통하여 개발된 부력가방은 편리성 안전성 지속성의 3가지 방재특성을 지니고 있으며, 서류 물품 등을 보관하는 편리성, 성인 1명 기준인 90 kg 무게를 띄울 수 있는 부력재를 내피 분산방식으로 처리한 안전성, 그리고 방수원단 및 방수지퍼 사용으로 장시간 안전을 유지하는 지속성 등을 갖춘 제품이다. 성능분석 결과 부력가방이 다른 구조장비와 비교해도 현장 간접 구조장비로 사용하는데 아무런 문제점이 없다는 것을 알 수 있었으며 부력성능과 디자인적인 측면만 더 보완하면 국민의 귀중한 생명을 보호하는데 많은 기여를 할 수 있을 것이다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권2호
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• pp.865-874
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• 2019

A controller for an underwater glider is presented. Considered underwater glider is a torpedo-shaped autonomous underwater vehicle installing adjustable buoyancy bag and movable battery in it. The controller is composed of an LQR controller to maintain zigzag vertical movement for gliding and two PD controllers to control elevator/rudder angles. The LQR controller controls the pumping speed into the buoyancy bag and the moving speed to locate the battery. One of the PD controller controls the elevator angle to assist the LQR controller, and the other controls the rudder angle to adjust the direction of the underwater glider. A reduced order Luenberger observer is adopted to estimates the center of gravity of the glider and the buoyancy mass that are essential but cannot be measured. Mathematical simulation using Matlab proved the validity of the proposed controller to obtain better performance than conventional LQR only controller under the influence of sea current.

• 대한임베디드공학회논문지
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• 제12권2호
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• pp.105-112
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• 2017

To control the depth of an underwater glider, a control method by using Lyapunov's direct method is proposed. The underwater glider has a torpedo-shape hull, a movable mass in the hull, and an inflatable buoyancy bag in the hull, but doesn't have large wings that increase the lift force for the conventional underwater glider. The control laws to adjust the position of the movable mass and the mass of the inflatable buoyancy bag are derived. For a selected speed and an angle of attack, we simulated the operation of the underwater glider using Matlab/Simulink. The efficiency of the proposed controller is shown in the fact that the control effort is active during only a short period of time when the zigzag trajectory is changed from downward to upward or vice versa.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.103-103
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• 2017

• 대한임베디드공학회논문지
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• 제12권5호
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• pp.311-318
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• 2017

A reduced order observer is developed for depth control of a hybrid underwater glider which combines the good aspects of a conventional autonomous underwater vehicle and a underwater glider. State variables include the center of gravity of the robot and the weight of the buoyancy bag, which can not be directly measured. By using the mathematical model and available information such as directional velocities, accelerations, and attitudes, we developed a Luenberger's reduced order observer to estimate the center of gravity and the buoyancy weight. By simulations using Matlab/Simulink, the efficiency of the proposed observer is shown, where a LQR controller using full state variables is adopted as a depth controller.

• 대한임베디드공학회논문지
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• 제14권1호
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• pp.25-31
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• 2019

An underwater glider is a type of autonomous unmanned vehicle and it advances using a vertical zig-zag glide. For this purpose, the position of an internal battery is regulated to control its attitude, and the amount of water in a buoyancy bag is regulated to control the depth. Underwater glider is suitable for a long-distance mission for a long time, because the required energy is much smaller than the conventional autonomous unmanned vehicle using propeller propulsion system. In this paper, control of horizontal tail wing is newly added to the conventional battery position and buoyancy control. The performance of the proposed controller is shown through Matlab simulation.

• 수산해양기술연구
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• 제60권3호
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• pp.207-216
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• 2024

This study conducted a marine experiment to improve the fishing system using miniaturized nets for anchovy boat seine to reduce the fleet size. As a result, the miniaturized net for anchovy boat seine properly opened the entrance of the bag net using the buoyancy of the flotation for position indication and the setting force of the ground rope without operating a separate fish detecting boat by attaching a large flotation at the entrances of the inside wing net and the bag net. This also enabled an operation type where the entrance of the bag net is confirmed using a flotation for position indication from a netting boat. The time and the number of people used for net casting and net hauling in the marine experiment were average of five minutes and 25-30 minutes, respectively, and 23-30 people for the existent net, while for the miniaturized large-scale net were average of three minutes and 23-25 minutes, respectively, and 19-25 people. This indicates that the operation time was shortened, the number of fish detecting boats was reduced by one boat, and the number of people for fishing work was decreased by four or five people due to the improvement of fishing operation system according to the reduction of fishing net size. As a result of measuring the shaft horsepower during net towing, the maximum net towing horsepower was 250 HP in comparison to the maximum RPM of the engine (1,200 RPM), indicating that the legal horsepower of 250 HP is enough to conduct net towing and the competitiveness of fishing using the net for anchovy boat seine is ensured through operation cost reduction.

• 해양환경안전학회지
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• 제5권1호
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• pp.29-36
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• 1999

인체의 표류특성을 규명하기 위해 1997년 8월부터 1998년 4월까지 실물을 이용한 현장실험을 실시하였다. 실험은 부산 영도구에 위치한 조도 부근해역에서 행하여졌고, 조난자로는 제중 60∼87kg, 키 170∼178 cm의 대학생들이 역할을 대신하였다. 실험중 조난자의 과도한 열손실을 방지하기 위해 네오프렌 재질의 5mm 잠수복을 착용하였다. 그리고 표류물체 주위의 유속 측정을 위해서는 비닐 백을 사용하였다. 결과 비교를 위해 조난자 옆에 스쿠버 장비를 갖추고 부력조절기에 바람을 가득 넣은 다이버를 함께 표류시켰다. 자료를 분석한 결과 잠수복만 입은 조난자 및 스쿠버 다이버의 평균 leeway rate는 각각 수면상 10m 높이 풍속의 약 0.4％와 1.3％이었다.

• 수산해양기술연구
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• 제29권3호
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• pp.200-213
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• 1993

A model experiment on a midwater rope trawl net which is used in the North Pacific to catch alaska pollack is carried out in the circulating tank to examine the basic efficiency of the net. The prototype is the net used by M/S Hanil(1, 179GT, 2, 700PS), a Korean trawler. The model net was made according to the Tauti's Similarity Law of Fishing Gear in 1/100 scale by considering the condition of the tank. To measure the basic efficiency of the standard model net, the vertical opening and width between some points marked on the net were measured, and the hydrodynamic resistance were determined. Then the constructive conditions of the net were varied as follows and the factors were measured again to compare the efficiency of those nets with that of the standard net(A-1 type) front weight multiplied 1.5 times: A-2 type. buoyancy and depressing force multiplied 1.7 times: A-3 type. front weight multiplied 1.5 times on A-3 type: A-4 type. depressors rigged at ground rope: B type. cod-end stuffed with cashmylon wad: C type. The results obtained can be summarized as follows: 1. The vertical opening at the center of head rope was steeply decreased with the flow velocity increasing and the vertical opening H(m) can be expressed in H=1.2v super(-1.2)(v : flow velocity in m/sec). The width of the net varied a little when the flow velocity was over 0.4m/sec, and the width of net mouth showed about 37% of the distance between the fore tips of net pendant. The shape of net mouth was almost a circle at 0.2m/sec and then steeply flatted elliptically with the flow velocity increasing and the area of mouth S(m super(2)) can be expressed in S=(1.65-2.3v)$\times$10 super(-2). The hydrodynamic resistance of the net increased almost linearly with the flow velocity increasing and the resistance R(kg) can be expressed in R=3.2$\times$d/l$\times$abv. where d/l denotes the mean of d(diameter of netting twine) and l(length of a leg in a mesh) from wing tip to the end of bag-net except cod-end on the side pannel, and a denotes the strectched circumference of the net at the fore end of a meshed part and b the stretched length of the whole net from wing tip to the end of cod-end. 2. In the condition-varied nets, the vertical opening of head rope showed some increase in every type net except the C type, and the increase showed the greatest in the B type by 30~54%, whereas it showed decrease in the C type by 5~10%. Variation of the area of net mouth showed almost the same tendency as the vertical opening and the increase showed the greatest in the B type by 20%, whereas it showed decrease in the C type by 12%. Hydrodynamic resistance showed some increase in every type compared with the standard net, and the rate of increase indicated 5~10% in the A-2, A-3 and A-4 type, 22% in the B type and 3% in the C type.