• 전자공학회논문지SC
• /
• 제44권6호
• /
• pp.35-41
• /
• 2007

자연스러운 머리 움직임 하에서 응시점을 추정할 수 있는 시스템을 제안하였다. 이 시스템은 하나의 카메라와 2개의 거울로 구성되어 있으며, 이 거울은 안구에서 눈동자의 영상을 언제나 카메라로 획득할 수 있도록 유지시키는 기능을 한다. 그러나 영상의 획득 속도가 초당 30 프레임이므로 거울의 제어가 빠른 머리 움직임을 보상할 수 없다. 이러한 문제점을 극복하고자 현재 안구 이미지에서 다음 안구 이미지의 위치를 추정하기 위하여 Kalman filter를 적용하였다. 그 결과 수평방향으로 평균 55cm/s, 수직 방향으로 평균 45cm/s정도의 속도의 머리 움직임에 대한 보상이 가능하였다. 그리고, 머리 움직임의 공간도 수평 60cm, 수직 30cm의 넓은 범위까지 가능하였다. 공간 해상도는 수평과 수직 각각 $4.5^{\circ}$와 $5^{\circ}$ 였고, 자연스러운 머리 움직임 아래에서의 응시점의 정확도는 92% 였다.

• 한국산업융합학회 논문집
• /
• 제23권3호
• /
• pp.433-444
• /
• 2020

This study proposes a method to improve the sleep stage and efficiency estimation of sleep apnea patients using a UWB (Ultra-Wideband) radar. Motion and respiration extracted from the radar signal were used. Respiratory signal disturbances by motion artifacts and irregular respiration patterns of sleep apnea patients are compensated for in the preprocessing stage. Preprocessing calculates the standard deviation of the respiration signal for a shift window of 15 seconds to estimate thresholds for compensation and applies it to the breathing signal. The method for estimating the sleep stage is based on the difference in amplitude of two kinds of smoothed respirations signals. In smoothing, the window size is set to 10 seconds and 34 seconds, respectively. The estimated feature was processed by the k-nearest neighbor classifier and the feature filtering model to discriminate between the sleep periods of the rapid eye movement (REM) and non-rapid eye movement (NREM). The feature filtering model reflects the characteristics of the REM sleep that occur continuously and the characteristics that mainly occur in the latter part of this stage. The sleep efficiency is estimated by using the sleep onset time and motion events. Sleep onset time uses estimated features from the gradient changes of the breathing signal. A motion event was applied based on the estimated energy change in the UWB signal. Sleep efficiency and sleep stage accuracy were assessed with polysomnography. The average sleep efficiency and sleep stage accuracy were estimated respectively to be about 96.3% and 88.8% in 18 sleep apnea subjects.

• Environmental Analysis Health and Toxicology
• /
• 제26권
• /
• pp.7.1-7.9
• /
• 2011

Objectives: This study was conducted to examine the relationship between crude oil exposure and physical symptoms among residents participating in clean-up work associated with the Hebei Spirit oil spill, 2007 in Korea. Methods: A total of 288 residents responded to a questionnaire regarding subjective physical symptoms, sociodemographic characteristics and clean-up activities that occurred between two and eight weeks after the accident. Additionally, the urine of 154 of the respondents was analyzed for metabolites of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) and heavy metals. To compare the urinary levels of exposure biomarkers, the urine of 39 inland residents who were not directly exposed to the oil spill were analyzed. Results: Residents exposed to oil remnants through clean-up work showed associations between physical symptoms and the exposure levels defined in various ways, including days of work, degree of skin contamination, and levels of some urinary exposure biomarkers of VOCs, metabolites and metals, although no major abnormalities in urinary exposure biomarkers were observed. Conclusions: This study provides evidence of a relationship between crude oil exposure and acute human health effects and suggests the need for follow-up to evaluate the exposure status and long-term health effects of clean-up participants.

• 전기학회논문지
• /
• 제60권12호
• /
• pp.2246-2253
• /
• 2011

This paper presents the error correction method of magnetic position sensor using recursive least square method (RLSM) with forgetting factor. Magnetic position sensor is proposed for linear position detection of the linear motor which has tooth shape stator, consists of permanent magnet, iron core and linear hall sensor, and generates sine and cosine waveforms according to the movement of the mover of the linear motor. From the output of magnetic position sensor, the position of the linear motor can be detected using arc-tan function. But the variation of the air gap between magnetic position sensor and the stator and the error in manufacturing process can cause the variation in offset, phase and amplitude of the generated waveforms when the linear motor moves. These variations in sine and cosine waveforms are changed according to the current linear motor position, and it is very difficult to compensate the errors using constant value. In this paper, the generated sine and cosine waveforms from the magnetic position sensor are compensated on-line using the RLSM with forgetting factor. And the speed observer is introduced to reduce the effect of uncompensated harmonic component. The approaches are verified by some simulations and experiments.

• 제어로봇시스템학회논문지
• /
• 제21권12호
• /
• pp.1167-1172
• /
• 2015

This paper describes the implementation of wearable AHRS for an electromagnetic motion capture system that can trace and analyze human motion on the principal nine axes of inertial sensors. The module provides a three-dimensional (3D) attitude and heading angles combining MEMS gyroscopes, accelerometers, and magnetometers based on the extended Kalman filter, and transmits the motion data to the 3D simulation via Wi-Fi to realize the unrestrained movement in open spaces. In particular, the accelerometer in AHRS is supposed to measure only the acceleration of gravity, but when a sensor moves with an external linear acceleration, the estimated linear acceleration could compensate the accelerometer data in order to improve the precision of measuring gravity direction. In addition, when an AHRS is attached in an arbitrary position of the human body, the compensation of the axis of rotation could improve the accuracy of the motion capture system.

• 한국HCI학회:학술대회논문집
• /
• 한국HCI학회 2008년도 학술대회 1부
• /
• pp.59-64
• /
• 2008

본 논문은 클라이언트/서버 구조의 촉감기반 네트워크 가상환경 시스템의 안정성을 평가하고, 네트워크 지연에 따른 촉감의 질적 저하 정도를 분석한다. 이를 통해서 안정성과 투명성을 위한 올바른 통신 구조를 도출하고 사용자가 요구하는 현실감 수준에 적합한 네트워크 상황의 예측 방법을 소개한다. 또한 네트워크 지연에 의해 생성되는 비현실적인 힘 피드백을 스프링 상수의 동적인 변경을 통해서 보상하는 네트워크 지연 보상기법을 제안한다. 촉감 기반 네트워크 응용프로그램을 기반으로 제안된 촉감기반 네트워크 가상환경 구조의 안정성 및 투명성 평가의 타당성을 검증하고 네트워크 지연 보상 기법의 유용성을 확인한다.

• 제어로봇시스템학회논문지
• /
• 제15권11호
• /
• pp.1122-1129
• /
• 2009

Recently taping robot with smart recognition function have been studied in the coil manufacturing field. Due to the difficulty of 3D surface processing from the complicated working environment, it is not easy to accomplish smart tape attachment motion with non-contact sensor. To solve these problems the applicable surface recognition algorithm and a flexible sensing device has been recommended. In this research, the fusion method between 1D displacement and 3D laser scanner is applied for robust tape attachment about cold rolled coil. With these sensors we develop a two-step exploration and the smart algorithm for the awareness of non-aligned coil's information. In the proposed robot system for tape attachment, the problem is reduced to coil's radius searching with laser displacement sensor at first, and then position and orientation detection with 3D laser scanner. To get the movement at the robot's base frame, the hand-eye compensation between robot's end effector and sensing device should be also carried out respectively. In this paper, we examine the auto-coordinate transformation method in the calibration step for the real environment usage. From the experimental results, it was shown that the taping motion of robot had a robust under the non-aligned cold rolled coil.

• 로봇학회논문지
• /
• 제5권4호
• /
• pp.309-317
• /
• 2010

This paper proposes an efficient measurement system for the velocity and direction of the wind using the dual rotor wind power generator in vessel. Conventional digital measurement system recognizes the direction and the velocity of the wind using the electric compass or synchronous motor and Vane probe method using hall sensors. But each system has its own short-comings: the synchronous motor has a larger measurement error than the magnetic compass and magnetic compass is weak for the external disturbances such as fluctuation of the vessel. To compensate these short-comings, this paper proposes a new compensation algorithm for the fluctuation errors according to the external interference and the unexpected movement of the vessel along the roll and pitch directions. The proposed system is implemented with the dual compasses and a synchronous motor. The proposed independent power generation system can be operated by itself and can raise the efficiency of the wind power generation systems of 30 ~ 400 W installed along the vertical and horizontal axes. The proposed system also realizes the efficient and reliable power production system by the MPPT algorithm for the real-time recognition of the wind direction and velocity. An advanced switching algorithm for the battery charging system has been also proposed. Effectiveness of the proposed algorithm has been verified through the real experiments and the results are demonstrated.

• 로봇학회논문지
• /
• 제15권4호
• /
• pp.341-349
• /
• 2020

Recently, interest in ground subsidence in urban areas has increased after a large sinkhole occurred near the high-story building area in Jamsil, Seoul, Korea, in 2014. If a massive sinkhole occurs in an urban area, it is crucial to assess its risk rapidly. Access to humans for on-site safety diagnosis may be difficult because of the additional risk of collapse in the disaster area. Generally, inspection using drones equipped with high-speed lidar sensors can be utilized. However, if the sinkhole is created vertically to a depth of 100 m, similar to the sinkhole in Guatemala, the drone cannot be applied because of the wireless communication limit and turbulence inside the sinkhole. In this study, a three-dimensional (3D) scanning system was fabricated and operated using a towed cable in a massive vertical sinkhole to a depth of 200 m. A high-speed lidar sensor was used to obtain a continuous cross-sectional shape at a certain depth. An inertial-measuring unit was applied to compensate for the error owing to the rotation and pendulum movement of the measuring unit. A reconstruction algorithm, including the compensation scheme, was developed. In a vertical hole with a depth of 180 m in the mining area, the fabricated system was applied to scan 0-165 m depth. The reconstructed shape was depicted in a 3D graph.

• 대한기계학회논문집
• /
• 제8권2호
• /
• pp.104-110
• /
• 1984

본 연구에서는 유압식 방법보다 절삭 정밀도가 높고 전기신호를 사용함으로 인한 조작과 증폭이 간단하고 특성 개선을 위한 조작과 증폭이 간단하고 특성 개선을 위한 계의 보상(sysyem compensation)을 할 수 있는 전기 유압식 모방장치를 설계, 제 작하여 그 성능을 실험적으로 해석하였다.