• Journal of the Korean Society for Railway
• /
• v.14 no.4
• /
• pp.364-369
• /
• 2011

For the safety management of tunnel, effective measurements should be continuously carried out. Most of sensors currently being applied for tunnels measure only the local status, thus many of them are needed to monitor an entire tunnel. For the railway tunnel where trains of same conditions are regularly operated, dynamic responses of tunnel structure to train operations can be a good index to estimate the deformation of tunnel structure in wide area. Meanwhile, the electromagnetic interference caused by overhead centenary in railway tunnel obstructs the use of electric-based sensors. In this study a brand new accelerometer using FBG optical fiber sensors is developed to solve these problems. Sensitivity and capacity of the accelerometer are enhanced with effective structural design of its components and verified with laboratory tests. A case history where the developed accelerometers were applied to a safety monitoring system of a high-speed train tunnel is presented. The performances of the developed accelerometers are validated from the measured acceleration data.

• Journal of the Korea Convergence Society
• /
• v.12 no.7
• /
• pp.263-271
• /
• 2021

Optoelectronic shooting training systems are used in shooting training sites to improve the accuracy of shooting by tracking the trajectories of gun movements. However, optoelectronic-based systems have limitations in terms of cost, complexity of installation, and the risk that electronic targets may be broken. In this study, we developed and verified a shooting training system that measures postural tremors using a low-cost accelerometer. The acceleration sensor module was designed to be attached to the air cylinder of a gun. Postural tremors were evaluated based on amplitude, frequency, and spatial pattern index, which were computed using acceleration data. The postural tremor indices between the accelerometer and optoelectronic-based system were highly correlated (left-right and up-down directions: r = 0.76 and r = 0.70, respectively). We validated the developed shooting training system using an independent two-sample t-test, which identified a significant difference (p < 0.05) in the calculated postural tremor index according to the athlete's shooting score (i.e., best and worst shots).

• Journal of Animal Science and Technology
• /
• v.64 no.6
• /
• pp.1237-1244
• /
• 2022

Horse breeders suffer massive economic losses due to dystocia, abortion, and stillbirths. In Thoroughbred mares, breeders often miss the foaling process because approximately 86% of the foaling events occur from 19:00 to 7:00; consequently, breeders cannot assist mares experiencing dystocia. To solve this problem, various foaling alarm systems have been developed. However, there is a need to develop a new system to overcome the shortcomings of the existing devices and improve their accuracy. To this end, the present study aimed to (1) develop a novel foaling alarm system and (2) compare its accuracy with that of the existing Foalert^TM system. Specifically, eighteen Thoroughbred mares (11.9 ± 4.0 years old) were included. An accelerometer was used to analyze specific foaling behaviors. Behavioral data were transmitted to a data server every second. Depending on the acceleration value, behaviors were automatically classified by the server as categorized behaviors 1 (behaviors without change in body rotation), 2 (behaviors with sudden change in body rotation, such as rolling over), and 3 (behaviors with long-term change in body rotation, such as lying down laterally). The system was designed to alarm when the duration of categorized behaviors 2 and 3 was 12.9% and that of categorized behavior 3 was 1% during 10 min. The system measured the duration of each categorized behavior every 10 min and transmitted an alarm to the breeders when foaling was detected. To confirm its accuracy, the foaling detection time of the novel system was compared with that of Foalert^TM. The novel foaling alarm system and Foalert^TM alarmed foaling onset respectively 32.6 ± 17.9 and 8.6 ± 1.0 min prior to foal discharge, and the foaling detection rate of both systems was 94.4%. Therefore, the novel foaling alarm system equipped with an accelerometer can precisely detect and alert foaling onset.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.5
• /
• pp.747-756
• /
• 2020

In recent years, measurement in a smart-phone environment is attracting attention in various fields due to its easy set-up process, various functions, convenience and expandability. Even in the field of safety evaluation and maintenance of large-scale infra-structures, the appropriate application of these effective and convenient measurement techniques can be of great help. In this paper, an experimental study was conducted to investigate the effectiveness, problems and complementary methods of applying smart-phone accelerometers to the measurement in infra-structure such as bridges. In model bridge subjected to impact and moving loads, the measured accelerations using a smart-phone and a professional accelerometer were directly compared in time domain. And the statistical and frequency characteristics of the measured signal and transfer function were also examined in frequency domain. The results show that the accuracy of measurement using smart-phone sensor is primarily affected by its incomplete sampling performance. In conclusion, smart-phone sensors cannot be considered suitable for precise assessment, where measurements must be accurate over a wide frequency range, but we can say that the technique is still useful and fairly accurate for some purpose over a limited frequency range, such as the low pass frequency range, which is a major concern for civil structures.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.2
• /
• pp.133-140
• /
• 2008

In this paper, a small and effective attitude estimation system for a humanoid robot was developed. Four small inertial sensors were packed and used for inertial measurements(3D accelerometer and three 1D gyroscopes.) An effective 3D pose estimation algorithm for low cost DSP using an extended Kalman filter was developed and evaluated. The 3D pose estimation algorithm has a very simple structure composed by 3 modules of a linear acceleration estimator, an external acceleration detector and an pseudo-accelerometer output estimator. The algorithm also has an effective switching structure based on probability and simple feedback loop for the extended Kalman filter. A special test equipment using linear motor for the testing of the 3D pose sensor was developed and the experimental results showed its very fast convergence to real values and effective responses. Popular DSP of TMS320F2812 was used to calculate robot's 3D attitude and translated acceleration, and the whole system were packed in a small size for humanoids robots. The output of the 3D sensors(pitch, roll, 3D linear acceleration, and 3D angular rate) can be transmitted to a humanoid robot at 200Hz frequency.

• Journal of Sensor Science and Technology
• /
• v.9 no.1
• /
• pp.1-8
• /
• 2000

One of today's very critical and sensitive accurate accelerometer which can be used higher temperature than $200^{\circ}C$ and corrosive environment, is particularly demanded for automotive engine. Because silicon is a material of large temperature dependent coefficient, and the piezoresistors are isolated with p-n junctions, and its leakage current increase with temperature, the performance of the silicon accelerometer degrades especially after $150^{\circ}C$. In this paper, The temperature characteristic of a accelerometer using silicon on insulator (SOI) structure is studied theoretically, and compared with experimental results. The temperature coefficients of sensitivity and offset voltage (TCS and TCO) are related to some factors such as thermal residual stress, and are expressed numerically. Thermal stress analysis of the accelerometer has also been carried out with the finite-element method(FEM) simulation program ANSYS. TCS of this accelerometer can be reduced to control the impurity concentration of piezoresistors, and TCO is related to factors such as process variation and thermal residual stress on the piezoresistors. In real packaging, The avarage thermal residual stress in the center support structure was estimated at around $3.7{\times}10^4Nm^{-2}^{\circ}C^{-1}$ at sensing resistor. The simulated ${\gamma}_{pT}$ of the center support structure was smaller than one-tenth as compared with that of the surrounding support structure.

• Journal of Sensor Science and Technology
• /
• v.6 no.5
• /
• pp.346-355
• /
• 1997

In this paper, the analyses of the stress disturibution and frequency characteristics of silicon microstructures for an accelerometer were performed using the general purpose finite element simulation program, ANSYS. From the analyses, we determined the parameter values of a new 6-beam piezoresistive accelerometer applicable to the accelerometer's specification in airbag system of automobile. Then, the mass paddle radius, beam length, beam width, and beam thickness of the designed accelerometer were$500{\mu}m$, $350{\mu}m$, $100{\mu}m$, and $5{\mu}m$, respectively and two different seismic masses with 0.4 mg and 0.8 mg were defined on the same sensor structure. The designed 6- beam accelerometers were fabricated on the selectively diffused (111)-oriented $n/n^{+}/n$ silicon substrates and the characteristics of the fabricated accelerometers were investigated. Then, we used a micromachining technique using porous silicon etching method for the formation of the micromechanical structure of the accelerometer.

• Korean Journal of Community Nutrition
• /
• v.22 no.5
• /
• pp.413-425
• /
• 2017

Objectives: Accurate assessment of energy expenditure is important for estimation of energy requirements in athletic children. The objective of this study was to evaluate the accuracy of accelerometer for prediction of selected activities' energy expenditure and intensity in athletic elementary school children. Methods: The present study involved 31 soccer players (16 males and 15 females) from an elementary school (9-12 years). During the measurements, children performed eight selected activities while simultaneously wearing the accelerometer and carrying the portable indirect calorimeter. Five equations (Freedson/Trost, Treuth, Pate, Puyau, Mattocks) were assessed for the prediction of energy expenditure from accelerometer counts, while Evenson equation was added for prediction of activity intensity, making six equations in total. The accuracy of accelerometer for energy prediction was assessed by comparing measured and predicted values, using the paired t-test. The intensity classification accuracy was evaluated with kappa statistics and ROC-Curve. Results: For activities of lying down, television viewing and reading, Freedson/Trost, Treuth were accurate in predicting energy expenditure. Regarding Pate, it was accurate for vacuuming and slow treadmill walking energy prediction. Mattocks was accurate in treadmill running activities. Concerning activity intensity classification accuracy, Pate (kappa=0.72) had the best performance across the four intensities (sedentary, light, moderate, vigorous). In case of the sedentary activities, all equations had a good prediction accuracy, while with light activities and Vigorous activities, Pate had an excellent accuracy (ROC-AUC=0.91, 0.94). For Moderate activities, all equations showed a poor performance. Conclusions: In conclusion, none of the assessed equations was accurate in predicting energy expenditure across all assessed activities in athletic children. For activity intensity classification, Pate had the best prediction accuracy.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.6
• /
• pp.234-240
• /
• 2002

This paper treats the problem of estimating the longitudinal velocity of a braking vehicle using measurements from an accelerometer and wheel speed data from standard anti-lock braking wheel speed sensors. We develop and experimentally test three velocity estimation algorithms of increasing complexity. The algorithm that works the best gives peak errors of less than 3 percent even when the accelerometer signal is significantly biased.

• 한국IT서비스학회:학술대회논문집
• /
• 2009.11a
• /
• pp.453-458
• /
• 2009

The purpose of this study was to detect early children with hyperactivity which is one of the symptoms of Attention Deficit - Hyperactivity Disorder (:ADHD). For this Purpose, This study used two methods; K-CBCL and observation of children`s behavior. K-CBCL was done online by parents at home. For observation of children's behavior, the school asked children to wear a 3 - axis accelerometer on their wrists. The data from K - CBCL and 3 - axis accelerometer were analyzed and clustered to separate hypersensitive children from ordinary children.