• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.135-140
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• 2021

In this paper is a study on system design to prevent accidents using accelerometers. A switching power FET was configured at the power supply stage, and DC-DC converter, a regulator, and an LDO were designed for the power supply. In order to solve the power problem at once, it was divided into two parts, and a 3-axis accelerometer was designed to extract motion information to safely prevent accidents. Microprocessor enables communication through I2C and UART communication ports, and enables debugging through J-LINK. As a result of measuring the acceleration sensor data, it was confirmed that the power is normally cut off to prevent accidents when motion at an angle of 30° or more is detected.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.303-309
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• 2012

Energy expenditure values were estimated based on the voice signals and body activities. Voice signals and body activities were obtained using PVDF contact vibration sensor and 3-axis accelerometer, respectively. Vibration caused by voices, activity signals, and actual energy consumption were acquired using data acquisition system and gas analyzer. With the use of power values from the voice signals and weight as independent variables, R-square of 0.918 appeared to show the highest value. For activity outputs, use of signal vector magnitude, body mass index, height, and age as independent variables revealed to provide the highest correlation with actual energy expenditure. Estimation of energy expenditure based on voice and activity provides more accurate results than based on activity only.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.1
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• pp.10-18
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• 2003

This paper presented a design and control of a biped walking RGO(robotic gait orthosis) and its simulation. The biped walking RGO was distinguished from the other one by which had a very light-weight and a new RGO system will be made of 12-servo motors and 12-controllers. The vibration evaluation of the dynamic PLS(posterior leaf splint) on the biped walking RGO was used to access by the 3-axis accelerometer with a low frequency vibration of less than 30 Hz. The galt of the biped walking RGO depends on the constrains of mechanical kinematics and the initial posture. The stability of dynamic walking was investigated by analyzing the ZMP (zero moment point) of the biped walking RGO. It was designed according to the human wear type and was able to accomodate itself to the environments of S.C.I. Patients. The Joints of each leg were adopted with a good kinematic characteristics. To analyse joint kinematic properties. we made the strain stress analysis of the dynamic PLS and the analysis study of FEM with a dynamic PLS.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.752-759
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• 2002

This paper presented a design and a control of a biped walking RGO and walking simulation by this system. The biped walking RGO was distinguished from the other one by which had a very light-weight and a new RGO type with 12-servo motors. The vibration evaluation of the dynamic PLS on the biped walking RGO was used to access by the 3-axis accelerometer with a low frequency vibration for the spinal cord injuries. The gait of a biped walking RGO depended on the constrains of mechanical kinematics and the initial posture. The stability of dynamic walking was investigated by a ZMP (Zero Moment Point) of the biped walking RGO. It was designed according to a human wear type and was able to accomodate itself to a human environments. The joints of each leg were adopted with a good kinematic characteristics. To test of the analysis of joint kinematic properties, we did the strain stress analysis of the dynamic PLS and the analysis study of FEM with a dynamic PLS. It will be expect that the spinal cord injury patients are able to recover effectively with a biped walking RGO.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.101-102
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• 2007

We demonstrate a novel calibration-free vehicle crash and rollover detect system by using a 3-axis accelerometer as a sensor element.

• The Journal of Korean Physical Therapy
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• v.27 no.2
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• pp.106-111
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• 2015

Purpose: Impaired reaching movement is commonly observed in children with cerebral palsy. The purpose of this study was to determine whether the inclination of seat surface can influence the reaching movement in children with spastic diplegic cerebral palsy (CP). Methods: The subjects were 31 children, 16 children with spastic bilateral CP and 15 typically developing (TD) children. The children performed static sitting and forward reaching under three conditions: a horizontal seat surface (Horizontal $0^{\circ}$), a seat surface inclined anterior 15 degrees (Ant $15^{\circ}$), and a seat surface inclined posterior 15 degrees (Post $15^{\circ}$). A 3-axis accelerometer ('ZSTAR3') was used for analysis of the reaching movement. A 3-axis accelerometer was attached on the manubrium of the sternum, lateral epicondyle of the humerus, and styloid process of the ulna. We measured the reaction time, movement time, and data amount during reaching the 8 cm target with an index finger on the three inclined seat surfaces. Results: Reaction time and movement time for CPs showed significant delay; comparing the TD's and CP's amount was significantly greater than the TD's during reaching task (p<0.05). In particular, CP's reaction time and movement time on a seat surface inclined Ant $15^{\circ}$ was significantly more delayed compared with the other seat surfaces (p<0.05). Conclusion: Our results suggest that seat-inclination intervention may provide an ergonomic approach for children with spastic cerebral palsy.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.26-33
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• 1999

In order to examine the effect of beam location n the performance of bridge type piozoresistive silicon accelerometer, three sensors having different location of beams were simulated by FEN(finite element method) and fabricated by RIE(reactive ion etching) and KOH etching method using SDB(silicon direct bonding) wafer, Results of the FEM simulation present that the 1st resonace frequency and Z axis sensitivity of each sensor are identical but the 2nd, and the 3rd resonace frequency and X, Y axis sensitivity are different. Even though the 1st resonance frequency and Z axis sensitivity measured from fabricated sensors do not perfectly coincide with each other, all 3 type sensors present 180 ~ 220N/G of Z sensitivity at 5 V supply voltage and 1.3 ~ 1.7kHz of the 1st resonance frequency and about 2% of lateral sensitivity.

• Journal of Internet Computing and Services
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• v.22 no.3
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• pp.9-16
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• 2021

This study aims to develop a human activity recognition (HAR) system as a Deep-Learning (DL) classification model, distinguishing various human activities. We solely rely on the signals from a wristband accelerometer worn by a person for the user's convenience. 3-axis sequential acceleration signal data are gathered within a predefined time-window-slice, and they are used as input to the classification system. We are particularly interested in developing a Deep-Learning model that can outperform conventional machine learning classification performance. A total of 13 activities based on the laboratory experiments' data are used for the initial performance comparison. We have improved classification performance using the Convolutional Neural Network (CNN) combined with an auto-encoder feature reduction and parameter tuning. With various publically available HAR datasets, we could also achieve significant improvement in HAR classification. Our CNN model is also compared against Recurrent-Neural-Network(RNN) with Long Short-Term Memory(LSTM) to demonstrate its superiority. Noticeably, our model could distinguish both general activities and near-identical activities such as sitting down on the chair and floor, with almost perfect classification accuracy.

• Journal of the Korea Safety Management & Science
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• v.14 no.1
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• pp.87-93
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• 2012

The purpose of this study suggests a personalized algorithm of physical activity energy expenditure prediction through comparison and analysis of individual physical activity. The research for a 3-axial accelerometer sensor has increased the role of physical activity in promoting health and preventing chronic disease has long been established. Estimating algorithm of physical activity energy expenditure was implemented by using a tri-axial accelerometer motion detector of the SVM(Signal Vector Magnitude) of 3-axis(x, y, z). A total of 10 participants(5 males and 5 females aged between 20 and 30 years). The activities protocol consisted of three types on treadmill; participants performed three treadmill activity at three speeds(3, 5, 8 km/h). These activities were repeated four weeks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.481-484
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• 2008

Sudden infant death syndrome (SIDS) is the leading cause of unexplained death of an apparently healthy infant aged one month to one year. This paper presents a infant monitoring system which detects the movement of infants to prevent SIDS. The proposed system is composed of an movement sensing part and a motion detecting part. The movement sensing part uses a tri-axis accelerometer. The motion detecting part is based on the LVQ algorithm. The proposed monitoring system connects to an alarm for alerting a parent when an infant is in a predetermined position. We evaluated the performance of the monitoring system through experiments.