• 한국해양공학회지
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• 제38권3호
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• pp.124-136
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• 2024

As the number of offshore wind-power installations increases, collision accidents with vessels occur more frequently. This study investigates the risk of collision damage with operating vessels that may occur during the operation of an offshore wind turbine. The floater used in the collision study is a 15 MW UMaine VolturnUS-S (semi-submersible type), and the colliding ships are selected as multi-purpose vessels, service operation vessels, or anchor-handling tug ships based on their operational purpose. Collision analysis is performed using ABAQUS and substantiation is performed via a drop impact test. The collision analyses are conducted by varying the ship velocity, displacement, collision angle, and ship shape. By applying this numerical model, the extent of damage and deformation of the collision area is confirmed. The analysis results show that a vessel with a bulbous bow can cause flooding, depending on the collision conditions. For damage caused by collision, various collision angles must be considered based on the internal stiffener arrangement. Additionally, the floater can be flooded with relatively small collision energy when the colliding vessel has a bulbous bow.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.40-46
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• 2013

Automatic swing door for an automotive application is considered. The equation of motion for a driver side swing door is introduced and gravity cancellation control scheme is adapted. The control scheme supposed to cancel the moment due to the tilt of the car. A speed control is suggested for door operation automation but the output of the speed control is not suppose to be precise as for the manufacturing system control. In the frame of the velocity control of the door, feedback linearization was applied for collision detection. The collision detection performance is satisfactory. The estimate of the magnitude of disturbance due to the collision is close to the actual magnitude of disturbance. Simulation study has been performed to gain insight into the system behavior. Also real test on the prototype hardware has been performed for verification purpose.

• 대한화학회지
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• 제56권5호
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• pp.548-555
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• 2012

Ultrasonic velocity and density measurements have been undertaken for a number of binary liquid mixtures involving different commercial solvent extractants, LIX reagents. The binary mixtures under investigation have been classified under two categories such as polar-polar, and polar-non-polar types. Different theories and relations such as Schaaff's Collision Factor Theory (CFT), Nomoto's relation (NOM), and Van Dael & Vangeel ideal mixing relation (IMR) have been used to evaluate the velocity theoretically for all these binary systems. The relative merits of afore-mentioned theories and relations compared to experimental values of velocity have been discussed in terms of percentage variations. However, the CFT and Nomoto's relation show better agreement with the experimental findings than the ideal mixing relation for all the systems under investigation.

• 로봇학회논문지
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• 제2권2호
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• pp.183-190
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• 2007

The most important thing for navigation of a mobile robot is to find the most suitable path and avoid the obstacles in the static and dynamic environment. This paper presents a method to search the optimal path in start space extended to time domain with considering a velocity and a direction of moving obstacles. A modified version of $A^*$ algorithm has been applied for path planning in this work and proposed a method of path search to avoid a collision with moving obstacle in space-tim domain with a velocity and an orientation of obstacles. The velocity and the direction for moving obstacle are assumed as linear form. The simulation result shows that a mobile robot navigates safely among moving obstacles of constant linear velocity. This work can be applied for not only a moving robot but also a legged humanoid robot and all fields where the path planning is required.

• 대한전기학회논문지:전력기술부문A
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• 제48권3호
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• pp.313-320
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• 1999

The Lane-Curvature Method(LCM) presented in this paper is a new local obstacle avoidance method for indoor mobile robots. The method combines Curvature-Velocith Method(CVM) with a new directional method called the Lane Method. The Lane Method divides the environment into lanes taking the information on obstacles and desired heading of the robot into account ; then it chooses the best lane to follow to optimize travel along a desired heading. A local heading is then calculated for entering and following the best lane, and CVM uses this heading to determine the optimal translational and rotational velocity space methods, LCM yields safe collision-free motion as well as smooth motion taking the dynamics of the robot Xavier, show the efficiency of the proposed method.

• 한국전산구조공학회논문집
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• 제24권6호
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• pp.691-697
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• 2011

본 연구에서는 방호공의 최대방호능력을 산정하기 위하여 선박충돌방호공과 선박을 수치적으로 모델링하고 준정적해석으로 충돌해석을 수행하였다. 방호공은 구조물의 비선형 거동과 지반의 지지효과 및 인발을 고려하여 모델링되었다. 충돌선박은 비선형거동이 집중되는 선수부분을 정밀하게 모델링하고 효율적인 해석을 위해 mass scaling기법을 사용하였다. 동일한 해석모델에 대하여 동적해석을 추가적으로 수행하여 두 해석방법의 차이점과 효율성을 평가하였다. 선박과 방호공의 에너지소산곡선을 바탕으로 충돌선박이 교량하부구조에 충돌력을 전달되는 시점을 추정하고, 이를 바탕으로 대상선박의 최대충돌허용속도를 산정하였다. 이러한 추정방법이 방호공의 에너지소산한계를 명확히 판단할 수 있어 공학적으로 효율적인 산정방법임을 보였다.

• 로봇학회논문지
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• 제12권3호
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• pp.258-262
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• 2017

In this paper, we propose a new collision detection algorithm for human-robot collaboration. We use an IMU sensor located at the tip of the manipulator and the kinematic behavior of the manipulator to detect the unexpected collision between the robotic manipulator and environment. Unlike other method, the developed algorithm uses only the kinematic relationship between the manipulator joint and the end effector. Therefore, the collision estimation signal is not affected by the error of the dynamics model. The proposed collision detection algorithm detects the collision by comparing the estimated acceleration of the end effector derived from the position, velocity and acceleration trajectories of the robot joints with the actual acceleration measured by the sensor. In simulation, we compare the performance of our method with the conventional Residual Observer (ROB). Our method is less sensitive to the load variation because of the independency on the dynamic modeling of the manipulator.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.171-180
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• 2001

Collision accident reconstruction algorithm are developed based on the deformation shape and severity of a car body. At first, the body stiffness equation representing the force-deformation relationship is derived using finite element analysis for head on collision of two cars. The database of deformation shapes and energies is constructed for five different collision configurations; each configuration contains three velocity conditions. Deformation shapes are obtained using a curve fitting method and result in cubic polynomials. Deformation energies are calculated using a stiffness equation and deformation data. Three algorithms are developed to reconstruct collision configuration compared with constructed database. The developed algorithms show reasonably good performance to find collisions conditions for some test problems.

• International Journal of Automotive Technology
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• 제5권3호
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• pp.173-180
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• 2004

An intensive study was conducted for the crash worthy structural design of the recently developed Korean High Speed Train (KHST). Two main design concepts were set up to protect both crews and passengers from serious injury in heavy collision accidents, and to reduce damage to the train itself in light collision accidents. A collision against a movable 15-ton rigid obstacle at 110 kph was selected from train accident investigations as the accident scenario for the heavy collisions. A train-to-train collision at the relative velocity of 16 kph was used for the light collision. The crashworthiness behaviors of KHST were numerically evaluated using FEM. Analysis results using 1-D collision dynamics model of the full rake consist and 3-D shell element model of the front end structure showed good crashworthy responses in a viewpoint of structural design. Occupant analyses and sled tests demonstrated that KHST performed well enough to protect occupants under the considered accident scenarios. Finally our numerical approaches were evaluated by a real scale collision test.

• 한국분무공학회지
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• 제13권4호
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• pp.187-192
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• 2008

In this study, the mechanisms of binary droplet collision were studied with diesel, ethanol and purified water. The droplet collisions of liquid droplet have been investigated for the same droplet diameter. In order to obtain the digital images of the droplet collision behavior, the experimental equipment was composed of the droplet generating system and the droplet visualization system. The droplets were produced by the vibrating orifice monodisperse generator. The visualization system consisted of a long distance microscope, a light source, and a high speed camera. The outcomes of binary droplet collision can be divided into four regimes, bouncing, coalescence, reflexive separation and stretching separation. The impact angle and the relative velocity of binary droplet are main parameters of collision phenomena, so the transition mechanism of droplet collision can be divided by the impact parameter.