• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.609-617
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• 2016

In general, Personal Navigation Systems (PNSs) can be defined systems to acquire pedestrian positional information. GPS is an example of PNS. However, GPS can only be used where the GPS signal can be received. Pedestrian Dead Reckoning (PDR) can estimate the positional information of pedestrians using Inertial Measurement Unit (IMU). Therefore, PDR can be used for GPS-disabled areas. This paper proposes a PDR scheme considering various movement types over GPS-disabled areas as combat environments. We propose a movement distance estimation scheme and movement direction estimation scheme as pedestrian's various movement types such as walking, running and crawling using IMU. Also, we propose a fusion algorithm between GPS and PDR to mitigate the lack of accuracy of positional information at the entrance to the building. The proposed algorithm has been tested in a real test bed. In the experimental results, the proposed algorithms exhibited an average position error distance of 5.64m and position error rate in goal point of 3.41% as a pedestrian traveled 0.6km.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.9 no.2
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• pp.137-144
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• 2015

In this paper, we present an inertial sensor-based gait analysis system to measure and analyze lower-limb movements. We developed an integral AHRS(Attitude Heading Reference System) using a combination of rate gyroscope, accelerometer and magnetometer sensor signals. Several AHRS modules mounted on segments of the patient's body provide the quaternions representing the patient segments's orientation in space. And a method is also proposed for calculating three-dimensional inter-segment joint angle which is an important bio-mechanical measure for a variety of applications related to rehabilitation. To evaluate the performance of our AHRS module, the Vicon motion capture system, which offers millimeter resolution of 3D spatial displacements and orientations, is used as a reference. The evaluation resulted in a RMSE(Root Mean Square Error) of 1.08 and 1.72 degree in yaw and pitch angle. In order to evaluate the performance of our the gait analysis system, we compared the joint angle for the hip, knee and ankle with those provided by Vicon system. The result shows that our system will provide an in-depth insight into the effectiveness, appropriate level of care, and feedback of the rehabilitation process by performing real-time limb or gait analysis during the post-stroke recovery.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.149-156
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• 2003

This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), an ultra-short baseline (USBL) acoustic navigation sensor and a doppler velocity log (DVL) accompanying a magnetic compass. The errors of inertial measurement units increase with time due to the bias errors of gyros and accelerometers. A navigational system model is derived to include the error model of the USBL acoustic navigation sensor and the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 25 in the order. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o.f. equations of motion of SAUV in a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass and a depth senor. The error of the estimated position still slowly drifts in horizontal plane about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1521-1527
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• 2013

This study proposes a wearable master device that can measure the joint stiffness and the angular displacement of a human operator to enhance the adapting capability of a slave system. A lightweight inertial sensor and the exoskeleton mechanism of the master device can make an operator feel comfortable, and artificial pneumatic muscles having a working principle similar to that of human muscles improve the performance of the slave device on emulating what a human operator does. Experimental results revealed that the proposed master/slave system based on the muscle stiffness sensor yielded uniform tracking performance compared with a conventional position-feedback controller when the payload applied to the slave system changed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.148-150
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• 2012

바람이나 파도에 의해서 요트 계류장과 요트 사이 또는 요트 계류장과 계류장 사이에는 충격이 발생하는데, 이러한 충격으로 인하여 계류장 또는 요트가 파손되거나 전복된다. 특히, 방파제 없이 외해에 설치한 요트 계류장은 이러한 위기에 항상 노출되어 있어 이에 대한 대책이 시급한 실정이다. 논문에서는 요트 계류장의 롤링, 히브, 핏칭 등의 운동을 측정하기 위한 하드웨어의 구축과 평가에 관해서 기술하였다. 하드웨어는 MEMS 기반 자이로와 가속도계 등의 관성 센서를 내장한 반도체 센서 SD746을 이용하여 구축하였고, 구축한 하드웨어를 이용하여 소형 요트 계류장에서 발생할 수 있는 운동을 수작업으로 생성하여 측정 및 평가하였다. 실험결과 x-축, y-축, z-축 등 3축 가속도와 3축 각속도 측정이 가능하여 요트 계류장의 운동 상태 모니터링이 가능함을 알았다. 본 연구는 추후 요트 계류장의 위기상태를 평가하고 통보하기 위한 시스템 구축에 이용할 예정이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2365-2370
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• 2017

In this paper, we propose a motion and position recognition technique considering an experiential VR environment. Motion recognition attaches a plurality of AHRS devices to a body part and defines a coordinate system based on this. Based on the 9 axis motion information measured from each AHRS device, the user's motion is recognized and the motion angle is corrected by extracting the joint angle between the body segments. The location recognition extracts the walking information from the inertial sensor of the AHRS device, recognizes the relative position, and corrects the cumulative error using the BLE fingerprint. To realize the proposed motion and position recognition technique, AHRS-based position recognition and joint angle extraction test were performed. The average error of the position recognition test was 0.25m and the average error of the joint angle extraction test was $3.2^{\circ}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.539-540
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• 2012

최근까지 무인 항공기는 군사적인 목적으로 활용하기 위해 활발하게 연구 되어 왔다. 근래에 들어 레저용, 또는 상업용으로 활용도가 급격히 증대되고 있다. 이에 국내외의 대학 및 연구기간에서 무인항공기의 자동비행 제어시스템을 위한 연구를 활발히 진행되고 있다. 최근 들어 무인항공기로 제어하기가 쉽고 활용도가 높은 쿼드로터 비행체가 각광을 받고 있는데 이미 많은 연구가 진행되어 왔다. 이러한 쿼드로터는 4개의 로터의 속도 제어로 비행체의 위치제어가 가능하다. 쿼드로터의 구조적인 이점으로 제어가 쉬운 반면 바람과 같은 외란에 매우 취약하다는 단점이 있어 실제 위치 제어가 쉽지가 않다. 본 논문에서는 외란(disturbance)에 취약한 쿼드로터의 위치제어를 안정하게 제어하기 위해 비행체의 자세 측정 센서인 관성측정장치(Inertial Measurement Unit)를 만들어 비행체의 자세를 측정 할 수 있도록 하였다. IMU는 자이로(Gyro)와 가속도(Accelerometer) 센서를 융합하여 비행체의 Roll, Pitch, Yaw 자세를 계측할 수 있도록 하였다. 본 논문에서는 일반적인 PID 제어기법을 적용하여 기존의 쿼드로터의 비행체에 대한 제어 성능을 실험을 제시하고자 한다.

• Journal of Aerospace System Engineering
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• v.6 no.4
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• pp.29-33
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• 2012

This paper is focusing on the difference from experiment result and method through dynamic loaded from impact analysis about inertia measure unit of high speed projectile. At Inertia measure unit dynamic load is applied when the high speed projectile is operated by impact to inside. it is necessary to design inertia measure unit enduring from external effect with operating environment. Investigation of material deformation with high strain speed is performed for military purpose, and still concerned to many scientist. From this study, this paper will prove of impact analysis result through comparing with experiment result and method when applied dynamic load.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.225-233
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• 2001

This paper deals with the transfer alignment problem of SDINS(StrapDown Inertial Navigation System) subjected to roll and pitch motions of the ship. Specifically, to reduce alignment errors induced by measurement time-delay and ship body flexure, an error compensation method is suggested based on delay state augmentation and DCM(Direction Cosine Matrix) partial matching. A linearized error model for the velocity and attitude matching transfer alignment system is first derived by linearizing the nonlinear measurement equation with respect to its time delay and augmenting the delay state into the conventional linear state equations. And then DCM partial matching is properly combined to reduce effects of a ship's Y axis flexure. The simulation results show that the suggested method is effective enough resulting in considerably less azimuth alignment errors.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.81-83
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• 2015

본 논문은 방송의 가상스튜디오 제작 환경에서 많이 사용되는 회전 또는 스크롤 메뉴를 진행자가 직접 휠(회전보드)을 움직여, 진행자와 그래픽과의 자연스러운 상호작용이 가능한 인터랙티브 가상현실 방송 제작 어플리케이션을 제안한다. 이를 위해, 우리는 물리적인 휠의 움직임을 인지할 수 있도록 관성측정장치(IMU: Inertial Measurement Unit)를 사용하였으며, IMU 센서가 부착된 휠을 크로마키로 처리하기 위해 푸른색의 페인팅된 물리적인 휠을 사용하였다. 본 어플리케이션을 통해서 가상스튜디오의 연기자는 물리적인 휠의 움직임을 느끼면서 휠을 회전시킴으로써 별도의 연습이나 훈련 없이도 직관적으로 회전하는 여러 타입의 가상 그래픽 메뉴를 제어할 수 있다. 우리는 상하 스크롤, 원형 회전, 스크롤 연동형 메뉴 어플리케이션들을 개발하였으며, 이것을 방송에 적용하여, 연기자와 휠에 연동한 그래픽과의 인터랙션이 자연스럽게 합성됨을 확인하였다.