• The Journal of Korean Physical Therapy
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• 제27권2호
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• pp.89-95
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• 2015

Purpose: The purpose of this study is to determine the effects of visual information on movement time and each angular velocity of trunk and lower extremity joints while healthy adults are in sitting and squat motion. Methods: Participants consisted of 20 healthy male and female adults; movement time and each angular velocity of trunk, pelvis, hip, knee and ankle of sitting and squat motion according to common vision, visual task and visual block were analyzed using a three dimensional motion analysis system. Results: Each angular velocity of the trunk, pelvis, hip, knee and ankle in phase 2 of the sitting showed significant difference according to the types of visual information (p<0.05). Movement time and each angular velocity of pelvis and hip in phase 2 of squat motion showed significant difference according to the types of visual information (p<0.05). According to the common vision, each angular velocity of knee and ankle in phase 1 was significantly fast in sitting (p<0.05). According to the common vision, each angular velocity of trunk, pelvis, hip, knee, and ankle in phase 2 was significantly fast in sitting (p<0.05). Conclusion: Visual information affects the angular velocity of the motion in a simple action such as sitting, and that in more complicated squat motion affects both the angular velocity and the movement time. In addition, according to the common vision, visual task and visual block, as angular velocities of all joints were faster in sitting than squat motion.

• International Journal of Internet, Broadcasting and Communication
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• 제12권3호
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• pp.1-8
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• 2020

This paper studied a method of estimating target information using a radar in wireless communication. Position information on the target can be estimated angle, distance and velocity. The velocity information can be estimated since the Doppler frequency is changed in the moving target. The signal incident on the receiving array antenna is multiplied by the delay time and the reference signal to represent the output signal. This output signal is estimated by applying FFT (Fast Fourier Transform) after calculating signal correlation through correlation integrator. Since the output signal must be calculated within the correlator, it should be processed with the Dwell time. The correlation signal of the correlation integrator outside this Dwell time is indicated by the velocity measurement error. The FFT is applied to the signal that has passed through the correlated integrator in order to estimate the distance of the signal. The Doppler resolution must be improved because the FFT estimates target information using the Doppler information. The Doppler resolution decreases with increasing the integration time. The velocity information estimation should have no spread of the velocity. As a result of the simulation, there was no spread of the target velocity in this study.

• 정보저장시스템학회논문집
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• 제1권1호
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• pp.99-107
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• 2005

According to recent trend, hard disk drive(HDD) has been smaller and less weight. Therefore, it needs new method of writing position information. In this thesis, a new controller that is suitable for SSW is proposed. The controller accepted SSW technology that is used to write position information in current HDD industry. The important condition to perform SSW is to reach constant velocity decided from the head velocity profile as fast as possible. The constant velocity decides the positional accuracy of spiral pattern and setup time decides the capacity of HDD. The head velocity profile as a reference signal must be designed not to cause resonance mode. The proposed controller was designed with consideration of these 3 elements, and it properly works for SSW. The velocity profile designed with SMART control not only minimizes the jerk, but also does not cause the resonance mode of a plant. After designing a conventional PID controller, it compared with electrical spring technique and ZPET technique.

• 전기학회논문지
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• 제62권6호
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• pp.852-862
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• 2013

This paper proposes a target tracking control method for wheeled mobile robots with nonholonomic constraints by using a backstepping-like feedback linearization. For the target tracking, we apply a vision system to mobile robots to obtain the relative posture information between the mobile robot and the target. The robots do not use the sensors to obtain the velocity information in this paper and therefore assumed the unknown velocities of both mobile robot and target. Instead, the proposed method uses only the maximum velocity information of the mobile robot and target. First, the pseudo command for the forward linear velocity and the heading direction angle are designed based on the kinematics by using the obtained image information. Then, the actual control inputs are designed to make the actual forward linear velocity and the heading direction angle follow the pseudo commands. Through simulations and experiments for the mobile robot we have confirmed that the proposed control method is able to track target even when the velocity sensors are not used at all.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.956-957
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• 2014

유속측정 레이다에서는 수신되는 도플러 신호의 스펙트럼을 추정함으로서 속도정보를 추출하게 된다. 그러나 저 유속인 경우 상대적으로 도플러 주파수 대역이 매우 저주파 영역에 나타나게 되며 이로 인하여 신호의 위상잡음이나 배경 클러터 등에 의한 영향을 심하게 받게 된다. 따라서 이러한 경우의 추정치 개선을 위한 방법을 분석하였다.

• ETRI Journal
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• 제27권5호
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• pp.563-568
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• 2005

A motion-control chip contains major functions that are necessary to control the position of each motor, such as generating velocity command profiles, reading motor positions, producing control signals, driving several types of servo amplifiers, and interfacing host processors. Existing motion-control chips can only generate velocity profiles of fixed characteristics, typically linear and s-shape smooth symmetric curves. But velocity profiles of these two characteristics are not optimal for all tasks in industrial robots and automation systems. Velocity profiles of other characteristics are preferred for some tasks. This paper proposes a motion-control chip to generate velocity profiles of desired acceleration and deceleration characteristics. The proposed motion-control chip is implemented with a field-programmable gate array by using the Very High-Speed Integrated Circuit Hardware Description Language and Handel-C. Experiments using velocity profiles of four different characteristics will be performed.

• 한국통신학회논문지
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• 제35권3C호
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• pp.295-301
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• 2010

본 논문에서는 프로펠러를 사용한 전자관악기를 위한 취구의 모델링 방법을 제안한다. 이 방법은 프로펠러의 각속도에 의한 바람의 세기를 계산을 빠르게 하도록 풍속계의 방식을 이용한 것이다. 풍속계의 경우에, 바람의 세기가 프로펠러의 각속도에 비례한다는 속성을 이용하여 바람의 세기를 계산한다. 하지만, 프로펠러의 각속도로부터 기대하는 바람의 세기가 계산되기까지 과도시간이 있기 때문에, 바람의 세기와 프로펠러의 각속도는 일대일대응이 아니다. 이 문제를 개선하기 위하여, 풍속계를 선형 시스템으로 해석하여, 그 시스템의 임펄스 응답과 프로펠러의 각속도를 디컨벌루션하여 바람의 세기를 추정한다. 실험으로 제안된 시스템의 타당성을 입증하기 위하여, 모터와 프로펠러, 엔코더로 구성된 취구 모델을 디자인하였다. 이 방법으로 바람의 세기를 추정한 결과는 이 시스템이 기존의 풍속계의 방법 보다 8배 빠른 시스템을 보여주었다.

• 한국컴퓨터정보학회논문지
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• 제18권9호
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• pp.71-78
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• 2013

본 논문에서는 골프채 헤드가 골프공을 일정속도로 움직여 치고 난 후 골프채의 헤드는 같은 방향으로 일정 속도로 움직일 때 골프공을 치고 날아가는 골프공의 속도를 구한다. 골프공을 치기 전의 속도가 각각 다를 경우의 골프공의 속도를 각각 구한다. 골프를 칠 때 헤드의 속도, 골프공의 질량, 임팩트, 임팩트후의 날아가는 속도, 그리고 임팩트 후의 이동 방향 등을 쉽게 알아보도록 하는 것이 본 논문의 목적이다. 실험 결과는 표와 그림으로 자세히 나타나 있고 본 연구와 기존 연구와의 비교 평가 결과와 시사점 및 향후 연구 방향도 제시하였다. 본 연구 결과는 다른 연구와 달리 몇 가지 요소들의 측정으로 우수하게 골프공의 속도를 측정함을 알 수 있다.

• 한국정보통신학회논문지
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• 제25권7호
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• pp.955-961
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• 2021

현대전에서는 전파를 이용하여 적의 정보를 알아내거나, 적이 탐지하려는 아군 정보를 보호하는 임무를 수행하는 전자전 분야의 중요성이 증가하고 있다. 전자전 분야의 대표적인 전자공격 방법 중 하나인 레이다 재밍기법은 적 레이다를 교란 및 기만하여 아군의 위치 정보가 노출되는 것을 방지한다. 레이다 재밍기법 중 하나인 속도기만 재밍기법은 도플러효과를 이용하여 표적의 속도와 위치를 추적하는 펄스 도플러 레이다를 대상으로 사용된다. 속도기만 재밍기법은 DRFM (Digital Radio Frequency Memory)을 이용하여 수신신호를 주파수 변조해서 송신하는 방법으로 구현할 수 있다. 본 논문은 위상 샘플방식 DRFM을 이용하여 속도기만 재밍기법 중 하나인 VGPO/VGPI 재밍기법을 구현하는 방안을 기술하고, 제작한 보드를 통해서 주입신호 환경 하에서 VGPO/VGPI 재밍기법의 동작을 검증하였다.

• International Journal of Control, Automation, and Systems
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• 제6권5호
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• pp.713-721
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• 2008

This paper presents the robust velocity estimation of an omnidirectional mobile robot using a polygonal array of optical mice that are installed at the bottom of the mobile robot. First, the velocity kinematics from a mobile robot to an array of optical mice is derived as an overdetermined linear system. The least squares velocity estimate of a mobile robot is then obtained, which becomes the same as the simple average for a regular polygonal arrangement of optical mice. Next, several practical issues that need be addressed for the use of the least squares mobile robot velocity estimation using optical mice are investigated, which include measurement noises, partial malfunctions, and imperfect installation. Finally, experimental results with different number of optical mice and under different floor surface conditions are given to demonstrate the validity and performance of the proposed least squares mobile robot velocity estimation method.