• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.3
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• pp.187-196
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• 2014

This paper suggests linearity enhancement algorithm to Ensure safety of Mobile Walker on Slope. Mobile Walker happens to get off track due to external forces from Walker's weight and the degree of the slope while slope driving. In order to compensate this, this research used the controller that estimates the external forces according to the slope of road surface and adjusts it to the motor output. Also, through comparisons between targeted rotational angular velocity which the user inputs and its velocity of the robot, algorithm was applied which applies a weight to each shaft. As a result of applying the proposed correction controller, it diverges in case of non-compensation experiments that deviates when moving, but it case of applying the ramp calibration algorithm, the deviation distance at max was within 10cm that it keeps safe driving, and change rate of deviation distance was also stabilized after 1m where no more changes occurred.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.261-268
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• 2013

In this paper, we propose the algorithm that improves the linearity of the walking assistant robot on lateral slopes. The walking assistant robot goes out of the course due to the rotational moment which is caused by the weight of the robot and the slope. To compensate this, we give the weight to each driving axle after comparing the real rotational angular velocity with the target rotational angular velocity which is entered by an user. The results of applying the algorithm to the real walking assistant robot show that the yaw axis deviation of the robot without the algorithm diverges, but the yaw axis deviation of the robot with the algorithm lies within 20cm, which can be recognized as stable. In addition, the changing rate of the course deviation is stabilized and shows no more course deviation, after moving 300cm.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.117-120
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• 2004

This paper is to investigate theoretically position fixing by using gyroscopic inertia of free gyroscope. with respect to a reference position or starting point, the changes of the inclination angle of the spin axes and the elapsed time are taken a measurement. By using the two basic factors like changes of angles a position is fixed.

• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.653-657
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• 2004

The authors aim to design further an upgraded and self-contained position fixing system to meet the future commercial requirements. As a first step this paper is to investigate the theoretical structure of position fixing based on the nature of free gyro, in which the tilt angles of the two spin axes at an arbitrary position are measured respectively and the elapsed time with respect to a reference position or starting point is observed And it illustrates some limitations to be expected in this system.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.3
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• pp.283-289
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• 2011

In this research a controller based on velocity estimator for a Wheeled Inverted Pendulum (WIP) is designed and various numerical simulation studies are carried out. The WIP has stable and unstable equivalent points. To Keep the unstable equilibrium point, a controller should control carefully the wheels persistently. There are angle, angular velocity, displacement, and velocity of the WIP for controller inputs. The velocity is obtained by differentiating the encoder signals from the motor and is subject to the resolution of the encoder. An improved velocity detection method is proposed based on low resolution encoder and velocity estimator. Various numerical simulations are carried out for showing the validation of the velocity estimator in case of the inclined road condition.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.448-455
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• 2019

This study aims to discover whether there are other factors, such as the ball position and address that will increase the percentage of holed putts from different angles of surface. In this study, we selected five male tour professional golfers that has been of 15 years or longer on the Korea Golf Association. As a research tool, after installing a video camera at an artificial site that's similar with the real green, and with the player's own putter, motion analysis was carried out using a Titleist V1x, which is commonly used by golfers. We use SPSS programs, significance level a=.05. According to the ball movement during the ball movement during the ball position putt by section, it is confirmed that the ball speed and angular velocity increase as the ball position changes from left to right. If the uphill putt, ball movement was found to be increased same change flat putt and There is no significance deviation. In this study, we investigate how the clubface and ball move during impact by varying the position of the address ball according to the slope during the ascent putt, which should increase the success rate among the various slopes. This study was conducted to present scientific data.

• Journal of the Korean Society of Visualization
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• v.16 no.1
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• pp.54-60
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• 2018

It is important to develop more efficient and productive casting processes for an automated high precision molten-metal casting system. Detailed analysis of molten-metal flow in the casting process by the numerical approach will help to optimize the control of a ladle. In this study, the smoothed particle hydrodynamics method was applied to analyze casting flow characteristics with different tilting angular speed and initial molten-metal level. The smoothed particle hydrodynamics technique has advantages to easily handle non-linear free surface behavior with the absence of a computational mesh. We found that tilting angular speed has relatively greater effect on the casting flowrate and that the effect of the initial molten-metal level is only minor. Further extensive study will be necessary to find an optimal condition for high efficient casting system.

• Proceedings of the Korea Contents Association Conference
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• 2010.05a
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• pp.161-163
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• 2010

본 연구의 목적은 등속성 운동수행 및 측정시 hip joint angle에 따라 대퇴근육의 concentric 과 eccentric 근력차이를 분석하기 위하여 등속성 기기 의자 등받이 경사각도를 $100^{\circ}$, $120^{\circ}$, $140^{\circ}$에서 peak torque를 검사하였다. 대상자는 20대 초반의 건강한 남자 대학생 12명을 대상으로, 등속성 기기(Isomed 2000, Germany)를 이용하여 seated position에서 $60^{\circ}/s$ 의 각속도를 사용하여 검사를 수행하였다. 측정순서는 등속성기기 의자 등받이 경사각도 $100^{\circ}$, $120^{\circ}$, $140^{\circ}$ 순으로 2-3일 간격으로 진행하였다. 통계처리 방법은 SPSS 12.0 프로그램을 이용하여 평균과 표준편차를 산출하였으며, 각각의 hip angle에 따른 단축성과 신장성 peak torque 값의 차이는 one-way ANOVA(3RM)을 이용하여 처리하였고, 사후검증은 Tukey를 사용하였으며, 유의수준은 p<.05로 하였다. 연구결과 대퇴사두근의 단축성 근력은 등속성 기기 의자 등받이 경사각 $100^{\circ}$, $120^{\circ}$, $140^{\circ}$사이에 유의한 차이(p=.000)가 나타나 사후 분석결과 $100^{\circ}$와 $120^{\circ}$ 사이(p<.01) 그리고 $100^{\circ}$와 $140^{\circ}$ 사이(p<.001)에 유의한 차이를 나타내었으며, 신장성 근력에서는 유의한 차이가 나타나지 않았다. 햄스트링의 단축성 근력은 3종류의 hip angle사이에 유의한 차이(p=.001)가 나타나 사후분석결과 $100^{\circ}$와 $140^{\circ}$사이(p<.05) 그리고 $120^{\circ}$와 $140^{\circ}$ 사이(p<.01)에 유의한 차이를 나타내었으며, 그러나 신장성 근력에서는 유의한 차이가 나타지 않았다. 이러한 결과로 미루어 볼 때 등속성 운동수행 및 근력측정 시 hip joint angle 에 따라 대퇴사두근과 햄스트링의 단축성 근력에서 유의한 차이가 나타나 hip joint angle을 고려하여 대퇴근육의 운동및 측정이 이루어져야 할 것으로 사료된다.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.649-656
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• 2003

In this paper we confirm the relation between the phase and phase error of the beat signal at the lock-in region of the dither type ring laser gyroscope by numerical calculation. We also study the requirement of the dither noise of an amplitude modulation type for statistical zero averaging of the beat signal phase error, without accumulation. As a result, we find that the dither noise requires the increase and decrease gradients of the dither amplitude, and those gradients should be combined with similar white noise. The slope of the gradient and maximum/minimum amplitude must be changed randomly. We confirm the error accumulation characteristic related to the dither noise by comparison of the two outputs during temperature change, by operating the two kinds dither noise, one is satisfied with the requirement and the other is not.

• Nuclear Engineering and Technology
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• v.27 no.5
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• pp.661-669
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• 1995

A mobile robot, named KAEROT, has been developed for inspection and maintenance operations in nuclear facilities. The main feature of locomotion system is the planetary wheel assembly with small wheels. This mechanism has been designed to be able to go over the stairs and obstacles with stability. This paper presents the inverse kinematic solution that is to be operated by remote control. The automatic stair climbing algorithm is also proposed. The. proposed algorithms generates the moving pathes of small wheels and calculates the angular velocity of 3 actuation wheels. The results of simulations and experiments are given for KAEROT peformed on the irregular stairs in laboratory. It is shown that the proposed algorithm provides the lower inclination angle of the robot body and increases its stability during navigation.