• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.2
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• pp.68-75
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• 2011

This paper describes the development of an open source motion sensor emulator. It helps developers to understand the motion sensor and its data better. Through this emulator, the realtime or stored motion sensor data can be applied to the applications that utilize motion sensors. The data of motion sensors which include accelerometer sensor, magnetic field sensor, gyro sensor, GPS, and so on, can be collected by using smart phones or motion sensors. We also describe a visualizer which shows various graphs, video and 3D animations based on the data sent by the emulator. It helps developers to understand motion sensors and how to use the sensors. The developed emulator is compatible with Android sensor simulator.

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

• The Journal of the Korea Contents Association
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• v.5 no.4
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• pp.94-102
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• 2005

In this paper, three axial accelerometer was used to develop a small sensor module, which was attached to human body to calculate the acceleration in gravity direction by human motion, when it was positioned in any direction. To measure its wearer's walking or running motion using the sensor module, the acquired sensor data was pre-processed to enable its quantitative analysis. The acquired digital data was transformed to orthogonal coordinate value in three dimension and calculated to be single scalar acceleration data in gravity direction and normalized to be physical unit value. The normalized sensor data was used to detect walking pattern and calculate their step counts. Developed algorithm was implemented in the form of PDA application. The accuracy of the developed sensor to detect step count was about 97% in laboratory experiment.

• 대한공업교육학회지
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• v.32 no.2
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• pp.171-187
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• 2007

The purpose of this study is to measure the lathe tool vibration and verify its usefulness using the fiber optic interferometeric sensor instead of using common accelerometer. To compare two vibration signals a Fabry-Perot fiber optic sensor(FOS) is directly attached to the left-side surface of the lathe tool and an accelerometer is attached near to the fiber optic sensor. Measurement signals from the FOS and theoretical results of receptance simulation are compared. When the amplitude of tool vibration increased the frequency shift phenomena was occurred. This means that mass effect occurred and vibration spectrum moved to the low frequency region. Generally this results is agreement to the regenerative chatter. The chatter frequency is not same as the natural frequency of the tool itself. The FOS can also applied to laboratory experiments for students. This experimental technique is perhaps the first attempts because of directly attachment technique. Therefore, suggested Fabry-Perot fiber optic sensor can be used to monitoring the tool wear and vibration.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.93-99
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• 2015

Economic burden of work-related musculoskeletal disorder(WMDs) is increasing. Known causes of WMDs include improper posture, repetition, load, and temperature of workplace. Among them, improper postures play an important role. A smart sensor called SensorTag is employed to estimate the trunk postures including flexion-extension, lateral bend, and the trunk rotational speeds. Measuring gravitational acceleration vector in the smart sensor along the tri-orthogonal axes offers an orientation of the object with the smart sensor attached to. The smart sensor is light in weight and has small form factor, making it an ideal wearable sensor for body posture measurement. Measured data from the smart senor is wirelessly transferred for analysis to a smartphone which has enough computing power, data storage and internet-connectivity, removing need for additional hardware for data post-processing. Based on the estimated body postures, WMDs risks can be conviently gauged by using existing WMDs risk assesment methods such as OWAS, RULA, REBA, etc.

• Journal of the Korea Society of Computer and Information
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• v.23 no.8
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• pp.17-23
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• 2018

In this paper, we implemented a flight posture simulator that intuitively understands aircraft flight posture and visualizes the principle of motion. The proposed system operates the 6 - axis motion platform according to the change of the navigation information and transmits the flight attitude to the simulator using the gyro sensor. A gyro sensor and an acceleration sensor are used together to analyze the attitude of the aircraft. The reason is that the gyro sensor has a cumulative error in the integration process. And the accelerometer sensor was compensated by using the complementary filter because noise was serious due to short term vibration. Using the compensated sensor information, the motion platform is operated by calculating the angle to be transmitted to the 6-axis motor. And visualization result is implemented using OpenGL. The results of this study can be used as teaching materials for students related to aviation in the future.

• Journal of Ocean Engineering and Technology
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• v.24 no.3
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• pp.1-10
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• 2010

In this study, hybrid smart sensor nodes were developed for the autonomous structural health monitoring of prestressed concrete (PSC) girders. In order to achieve the objective, the following approaches were implemented. First, we show how two types of smart sensor nodes for the hybrid health monitoring were developed. One was an acceleration-based smart sensor node using an MEMS accelerometer to monitor the overall damage in concrete girders. The other was an impedance-based smart sensor node for monitoring the local damage in prestressing tendons. Second, a hybrid monitoring algorithm using these smart sensor nodes is proposed for the autonomous structural health monitoring of PSC girders. Finally, we show how the performance of the developed system was evaluated using a lab-scaled PSC girder model for which dynamic tests were performed on a series of prestress-loss cases and girder damage cases.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.249-252
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• 2008

A wearable ubiquitous health care monitoring system using integrated ECG and accelerometersensors based on WSN is designed and developed. Wireless sensor network technology is applied for non intrusive healthcare in some wide area coverage with small battery support for RF transmission. We developed wearable devices which are wearable USN node, sensor board and base-station. Low power operating ECG and accelerometer sensor board was integrated to wearable USN node for user's health monitoring. The wearable ubiquitous healthcare monitoring system allows physiological data to be transmitted in wireless sensor network from on body wearable sensor devices to a base-station connected to server PC using IEEE 802.15.4. Physiological data displays and stores on server PC continuously.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1856-1864
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• 2015

In this paper, the localization algorithm for improving the accuracy of the positioning using the Wi-Fi fingerprint using the normal distribution probability and the built-in typed accelerometer sensor, the gyroscope sensor of smartphone in the indoor environment is proposed. The experiments for analyzing the performance of the proposed algorithm were carried out at the region of the horizontal and vertical 20m * 10m in the engineering school building of our university, and the performance of the proposed algorithm is compared with the fingerprint and the DR (dead reckoning) while user is moving according to the assigned region. As a result, the maximum error distance in the proposed algorithm was decreased to 2cm and 36cm compared with two algorithms, respectively. In addition to this, the maximum error distance was also less than compared with two algorithms as 16.64cm and 36.25cm, respectively. It can be seen that the fingerprint map searching time of the proposed algorithm was also reduced to 0.15 seconds compared with two algorithms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6399-6405
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• 2014

An external overload or impact is an important factor affecting the safety of large-scale structures. The proposal of this paper is the development of a system for detecting overload and impulse using a single PVDF film sensor. In large-scale structures, the load causes the structure to be deformed and the impulse generates vibration on the structure. Generally, low frequency deformation or bending of a structure is measured with a strain gauge and the high frequency vibration is detected by an accelerometer. On the other hand, a single sensor that can detect both deformation and vibration has not been developed. In this study, the development of a detection system integrated with a polyvinylidene fluoride (PVDF) film sensor, amplifier, and software was attempted to monitor deformation and impact through a single sensor. The system was verified by the possibility of detecting overload and impulse, and the two filtered signals of the PVDF were compared with a conventional strain gauge and an accelerometer.