• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.33-37
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• 2024

Recently, wearable virtual reality devices are widely used. These instruments include a 3-axis accelerometer. User's heart rate information in virtual reality contents can be useful for measuring user experience. In this paper, we propose a method to measure the heart rate through a 3-axis accelerometer based on the principle of ballistocardiography without additional sensors. The angular velocity was successively measured in a time series by the 3-axis accelerometer mounted to the head. The frequency of the maximum magnitude is determined as the heart rate through frequency transform and band pass filtering of the time series signal. For verification, the heart rate calculated from photoplethysmography sensors acquired at the same time was compared as ground-truth. In the virtual reality, the user's heart rate information can be extracted without additional heart rate sensor, and the emotional state and fatigue can be measured.

• 인터넷정보학회논문지
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• 제11권1호
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• pp.129-141
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• 2010

본 논문에서는 사람의 행동 모니터링을 위한 멀티 센서 기반의 웨어러블 지능형 디바이스를 제안한다. 다중 행동을 인식하기 위해, 이미지 센서와 가속도 센서를 이용하여 행동 인식 알고리즘을 개발하였다. 멀티 센서로부터 얻은 데이터를 분석하기 위해 그리드 기반 옵티컬 플로우 방법을 제안하고 SVM 분류기법을 이용하였다. 이미지 센서로부터 얻은 모션 벡터의 방향과 크기를 이용하였고, 3축 가속도 센서로부터 얻은 데이터에서 FFT의 축과 크기와의 상관관계를 계산하였다. 실험 결과에서 이미지 센서 기반과 3축 가속도 센서기반의 행동 인식률은 각각 55.57 %, 89.97%를 보였으나 제안한 멀티센서기반의 행동인식률은 92.78% 를 보였다.

• 제어로봇시스템학회논문지
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• 제18권7호
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• pp.632-637
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• 2012

This paper introduces a simple and efficient calibration method for three-axis accelerometers and three-axis gyroscopes using three-axis motion rate table. Usually, the performance of low cost MEMS-based inertial sensors is affected by scale and bias errors significantly. The calibration of these errors is a bothersome problem, but the previous calibration methods cannot propose simple and efficient method to calibrate the errors of three-axis inertial sensors. This paper introduces a new simple and efficient method for the calibration of accelerometer and gyroscope. By using a three-axis motion rate table, this method can calibrate the accelerometer and gyroscope simultaneously and simply. Experimental results confirm the performance of the proposed method.

• 한국정보전자통신기술학회논문지
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• 제2권4호
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• pp.53-58
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• 2009

최근 각 종 분야에서 센서들을 이용한 연구 및 활용도가 증가하고 있다. 본 논문에서 는 3축 가속도 센서를 이용해 serial 통신을 통한 물체의 기울기를 감지 및 검출 하고 사용자는 실시간으로 모니터링 할 수 있는 GUI 환경 및 기울기 감지 시스템을 제안하였다. 기존 전자식 액체충전 방식의 기울기 센서의 불안정한 데이터와 오차의 단점을 줄이고자 AD 변환기가 내장된 디지털식 3축 가속도 센서를 이용함으로서, 보다 정확한 데이터를 검출하여 정확도를 높이고 사용자는 이상 여부를 보다 쉽게 인식할 수 있었다.

• 로봇학회논문지
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• 제5권4호
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• pp.279-285
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• 2010

This paper presents the use of 3 axis accelerometer for getting the gait information including the number of gaits, stride and walking distance. Travel distance is usually calculated from the double integration of the accelerometer output with respect to time; however, the accumulated errors due to the drift are inevitable. The orientation change of the accelerometer also causes error because the gravity is added to the measured acceleration. Unless three axis orientations are completely identified, the accelerometer alone does not provide correct acceleration for estimating the travel distance. We proposed a way of minimizing the error due to the change of the orientation. Pedestrian localization is implemented with the heading angle and the travel distance. Heading angle is estimated from the rate gyro and the magnetic compass measurements. The performance of the localization is presented with experimental data.

• 산업경영시스템학회지
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• 제33권2호
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• pp.105-111
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• 2010

The purpose of this study was to detect early children with hyperactivity which is one of the symptoms of Attention Deficit-Hyperactivity Disorder (ADHD). 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. This experiment confirmed that 3-axis accelerometer which is one of Ubiquitous techniques and the K-CBCL questionnaire were helpful for detection of hypersensitive children.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권5호
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• pp.361-367
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• 2004

This paper describes design of an algorithm for analyzing human activity using body-fixed 3-axis accelerometer in the small of the back. In the first step, we distinguish static and dynamic activity period using AC signal analysis. Then five postures were classified by applying the threshold in DC signal corresponding to the static activity period. Also, after comparison of average power and taking negative peak signal in the dynamic activity period, the four dynamic activities were classified by adaptive threshold method. To evaluate the performance of the proposed algorithm, the measured signals obtained from six subjects were applied to the proposed algorithm and the results were compared with the simultaneously measured video data. As a result, the activity classification rate of 95.7％ on average was obtained. Overall results show that the proposed classification algorithm has a possibility to be used to analyze the static and dynamic physical activity.

• 동의신경정신과학회지
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• 제31권4호
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• pp.225-233
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• 2020

Objectives: This study aimed to reveal the gait characteristics of each Sasang constitution by examining the differences in gait analysis indicators using a 3-axis accelerometer. Methods: Ninety-one participants were classified through the TS-QSCD (Two-Step Questionnaire for Sasang Constitution Diagnosis) method and gait analysis was performed using a 3-Axis Accelerometer (G-WALK. BTS Bioengineering, Italy). Gait analysis in returning to the 6-meter turnaround point and 6-minute walking test were performed. The differences in the gait analysis index values were analyzed between each constitution. Results: The gait analysis of 91 subjects (37 Taeumin, 37 Soyangin, and 17 Soeumin), showed that the percent stride length/height in the Soyangin subjects was significantly higher than that of the Taeeumin and Soeuminin subjects in the spatiotemporal walking variables (p<0.05). Stride length also showed the widest tendency in the Soyangin subjects (p=0.05). In the kinesiological analysis, the range of pelvic obliquity angles in the Soeumin subjects was significantly wider than that of the Taeumin and Soyangin subjects (p<0.05). In the six-minute walking test, the Soyangin subjects walked the farthest at 309.41±35.23 m (p=0.064). Conclusions: In a comparison of the gait characteristics for each Sasang constitution using a three-dimensional accelerometer, the stride width of the Soyangin subjects was the widest compared to the Taeeumin, and Soeumin subjects, and Soyangin's walking speed showed a faster tendency than that of the Taeeumin and Soeumin subjects.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1043-1047
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• 2003

Most of the measurement and the evaluation of hand-transmitted vibration have been performed by using a small size single axis accelerometer between the handle and the hand palm or a three axis accelerometer attached on an adapter outside the hand(indirect measurement). It is most desirable for the correct evaluation of hand-transmitted vibration form the power tool handle to measure the acceleration between the handle surface and the hand palm in the three axis(direct measurement) as recommended in ISO 5349-1. In the study three axes acceleration measurement device was developed of which the thickness was less than 7mm so that it can be placed between the handle and the palm without any inconvenience during the measurement. To verify the performance of the developed device, measured acceleration by the two methods, direct and indirect, were compared in the study.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.396-398
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• 2009

Scoliosis is a three-dimensional deformity caused by lateral curvature of the spine. The existing braces used to correct the posture were some drawbacks such as inconvenience, tightness as well as unfitness to wear. In this study, we devised a posture guidance system in order to monitor a posture continuously and lead to pose correctly and a new method fur measuring a Cobb's angle value in third dimension based on two 3-axis accelerometers. As a result, the correlation coefficients between desired and measured angles were and standard error between desired and measured angles were 0.99, 1.32(x-axis), 0.99 and 1.10(y-axis), respectively. The devised system showed good potential for the optimal posture guide and an early detection of scoliosis.