• 제어로봇시스템학회논문지
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• 제7권9호
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• pp.741-748
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• 2001

In this paper, we propose a method of tracking and capturing a moving object by a mobile robot. The position of the moving object is acquired from the relation through color-based image information from a 2-DOF active camera mounted on the mobile robot. The direction and rotational angular velocity of the moving object are estimated using a state estimator. A Kalman fiber is used as the state estimator for taking characteristics of robustness against noises and uncertainties included in the input data. After estimating the trajectory of the moving object, we decide on the optimal trajectory and plan the motion of the mobile robot to capture the target object within the shortest distance and time. The effectiveness of the proposed method is demonstrated by the simulations and experiments.

• 한국정보통신학회논문지
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• 제15권4호
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• pp.886-890
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• 2011

유도전동기는 상대적으로 저가이며 보수가 용이하여 산업 및 여러 분야에서 많이 사용되고 있는 전동기이다. 유도전동기의 정확한 속도 및 토크 제어를 위해서 회전자의 속도 및 위치정보가 요구된다. 회전자의 위치 및 속도 센서들은 경제성 및 주위 환경에 따른 센서의 신뢰도 감소 문제를 가져온다. 최근에는 이러한 경제성 및 신뢰성 향상을 위하여 속도 및 위치센서를 사용하지 않는 센서리스 제어방식의 연구가 많이 이루어지고 있다. 대부분의 센서리스제어 방식에서 위치 및 속도추정은 전동기 전압방정식으로부터 계산된다. 따라서 파라미터 오차는 센서리스 제어성능에 큰 영향을 미치게 된다. 본 논문에서는 유도전동기의 속도 추정에서 회전자 저항 오차에 의해 발생하는 속도 오차를 보상하기 위하여 회전자 저항 보상방식을 제안한다. 본 논문에서 제안한 방식은 컴퓨터 시뮬레이션 및 실험을 통하여 검증한다.

• 대한기계학회논문집
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• 제18권12호
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• pp.3386-3394
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• 1994

An experimental study has been performed on the flow over a rotating disk, where the diameter of the disk is 500 mm and the maximum vertical deviation of the upper surface is $50 \mu{m}$ for the whole range of the angular velocity up to 3400 rpm. The flow visualization experiment for the wall jet flow induced by impinging circular jet is carried out using schlieren system and measurements are made by 3-hole and 5-hole pitot tubes. Schlieren photographs show that as the rotating speed increases the wall jet flow becomes more stable and the size of the largest eddies becomes smaller. Measurements for impinging jet flow on the stationary disk verify the accuracy of the present experiment, and those for free rotating disk flow display the existence of transition region from laminar to turbulent flows. Measurements for impinging jet flow on the rotating disk exhibit the interaction between the wall jet and the viscous pumping effect, which explains the decay in size of turbulent eddies illustrated by the schlieren photographs.

• 대한기계학회논문집
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• 제19권9호
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• pp.2223-2236
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• 1995

0The fields of turbomachinery and electrical generators provide many examples of flow through rotating internal passages. At the practicing Reynolds number, most of the flow motion is three dimensional and highly turbulent. The proper understanding for the characteristics of these turbulent flow is necessary for the design of thermo-fluid machinery of a good efficiency. The flow characteristics in the rotating duct with curvature are very complex in practice due to the curvature and rotational effect of the duct. The understanding of the effect of the curvature on the structure and rotational effect of the duct. The understanding of the effect of the curvature on the structure of turbulence in the curved passage and the characteristics of the flow in a rotating radial straight channel have been well studied separately by many workers. But the combined effects of curvature and rotation on the flow have not been well understood inspite of the importance of the phenomena in the practical design process. In this study, the characteristics of a developing turbulent flow in a square sectioned 90.deg. bend rotating at a constant angular velocity are measured by using hot-wire anemometer to seize the rotational effects on the flow characteristics. As the results of this study, centrifugal forces associated with the curvature of the bend and Coriolis forces and centripetal forces associated with the rotational affect directly both the mean motion and the turbulent fluctuations.

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.703-710
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• 2010

최근 신재생에너지 연구개발과 관련하여 소수력발전에 대한 관심이 높아지고 있지만, 기존의 대수력용 수차 시스템과는 달리 소수력에 적당한 수차의 설계법이 아직 확립되어 있지 않기 때문에 고성능의 소수력용 수차의 개발이 요구되고 있다. 그러나, 복잡한 터빈의 구조에 의한 상대적으로 높은 제작단가는 소수력발전용 터빈의 개발에 큰 걸림돌로 작용하고 있다. 따라서, 본 연구에서는 수차의 형상이 상대적으로 간단하고 소수력자원에 적용하기가 용이한 80kW급 횡류형 수차에 대하여 유효낙차 변화에 따른 성능 및 내부유동에 대해서 검토하였다. 유효낙차가 증가함에 따라서 원주방향 및 반경방향 속도비가 증가하게 되며, 증가한 원주속도에 의해 각운동량이 증가하여 출력도 커지게 된다.

• 대한물리의학회지
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• 제12권1호
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• pp.51-59
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• 2017

PURPOSE: This study compared cognitive task-directed functional motor control ability for reaching and kicking movements in younger and older adults. METHODS: Subjects were divided into two groups of younger and older adults, with 13 subjects in each group. Subjects were required to perform a dual task combining a functional movement and cognitive component. The task consisted of reaching and kicking movements. Participants performed indicated movements when a target appeared on a monitor. The target randomly appeared on the monitor every 10 seconds. The total performance time (TPT), joint angular velocity (JAV), and muscle activation time were used to evaluate motor control ability. RESULTS: There were significant differences in all evaluation factors in a comparison of younger and older adults (p<.05). TPT was significantly shorter in older adults, and JAV and muscle activation time were significantly slower than that in the younger adult group. Although the results for older adults were within the normal range for functional assessment, their motor control abilities were significantly worse for cognitive tasks compared with those of younger adults. CONCLUSION: The results of this study indicated that a motor control assessment tool using a cognitive task would be helpful in assessment of motor control ability in healthy older adults.

• 한국조명전기설비학회지:조명전기설비
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• 제9권6호
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• pp.57-64
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• 1995

본 논문에서는 산업용 구동력으로써 대부분을 차지하는 유도전동기의 가변속 구동시 성능이 우수한 벡터제어 시스템에 관하여 연구하였다. 유도전동기의 회전자 각속도와 고정자 전류에 의한 간접적인 회전자 기준자속 추정방식을 채택하였으며, 이때의 전류제어기는 상호 간섭이 일어나지 않는 비간섭 동기 회전좌표계 PI제어기를 구성하였으며 시스템을 견실하게 하였다. 공간전압벡터 변조기법을 적용하여 전압 이용율의 향상과 전류제어가 용이하도록 하였다. 기기의 모델링 및 디지털 시뮬레이션을 통하여 속응성과 원활한 제어특성이 나타나는 유도전동기 구동시스템임을 입증하였다.

• 한국산업융합학회 논문집
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• 제3권2호
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• pp.131-139
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• 2000

Gear train in the automobile to be used for controlling gas flow in automobiles consists of spur gears with involute tooth type in multiple stages. This spur gear is designed considering to the high power transfer efficiency, bending stress and contact stress in the static and dynamic analysis. The torque has been increased simultaneously the angular velocity has been decreased through the stages after being supplied by AC synchronous motor. This apparatus is controlled by electrical devices such as the PIC microprocessor, hall sensor and other electric components. By comparing the preset data of PIC microcomputer which is supplied by external DC electric power with the value set of hall sensor which detects the rotation angle position, PIC microcomputer thus controls AC motor and gear train according to the program algorithm which includes the on-off control and PWM motor driving method. As the result of the experiment such as performance, fatigue, torque test, we can conclude that this system is superior to the same and familiar foreign systems.

• Ocean Systems Engineering
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• 제7권3호
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• pp.299-318
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• 2017

The paper aims at illustrating several key issues and ongoing efforts for development of a reliable fully-Lagrangian particle-based solver for simulation of hydroelastic slamming. Fluid model is founded on the solution of Navier-Stokes along with continuity equations via an enhanced version of a projection-based particle method, namely, Moving Particle Semi-implicit (MPS) method. The fluid model is carefully coupled with a structure model on the basis of conservation of linear and angular momenta for an elastic solid. The developed coupled FSI (Fluid-Structure Interaction) solver is applied to simulations of high velocity impact of an elastic aluminum wedge and hydroelastic slammings of marine panels. Validations are made both qualitatively and quantitatively in terms of reproduced pressure as well as structure deformation. Several remaining challenges as well as important key issues are highlighted. At last, a recently developed multi-scale MPS method is incorporated in the developed FSI solver towards enhancement of its adaptivity.

• Fisheries and Aquatic Sciences
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• 제11권1호
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• pp.61-69
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• 2008

Using empirical data of fish performance and physiological limits as well as physical stimuli and environmental data, a cod-end selectivity model based on a chaotic behavior model using the psycho-hydraulic wheel and neural-network approach was established to predict fish escape or herding responses in trawl and cod-end designs. Fish responses in the cod-end were categorized as escape or herding reactions based on their relative positions and reactions to the net wall. Fish movements were regulated by three factors: escape time, a visual looming effect, and an index of body girth-mesh size. The model was applied to haddock in a North Sea bottom trawl including frequencies of movement components, swimming speed, angular velocity, distance to net wall, and the caught-fish ratio; simulation results were similar to field observations. The ratio of retained fish in the cod-end was limited to 37-95% by optomotor coefficient values of 0.3-1.0 and to 13-67% by looming coefficient values of 0.1-1.0. The selectivity curves generated by this model were sensitive to changes in mesh size, towing speed, mesh type, and mesh shape.