• 한국전기전자재료학회논문지
• /
• 제24권1호
• /
• pp.81-88
• /
• 2011

A real time monitoring system from a PC has been developed which can be accessed through transmitted data, which incorporates an established low powered transport system equipped with a single chip combined with wireless sensor network technology from a three-axis acceleration sensor. In order to distinguish between static posture and dynamic posture, the extracted parameter from the rapidly transmitted data needs differentiation of movement and activity structures and status for an accurate measurement. When results interpret a static formation, statistics referring to each respective formation, known as the K-mean algorithm is utilized to carry out a determination of detailed positioning, and when results alter towards dynamic activity, fuzzy algorithm (fuzzy categorizer), which is the relationship between speed and ISVM, is used to categorize activity levels into 4 stages. Also, the ISVM is calculated with the instrumented acceleration speed on the running machine according to various speeds and its relationship with kinetic energy goes through correlation analysis. With the evaluation of the proposed system, the accuracy level stands at 100% at a static formation and also a 96.79% accuracy with kinetic energy and we can easily determine the energy consumption through the relationship between ISVM and kinetic energy.

• 대한전자공학회논문지SD
• /
• 제46권10호
• /
• pp.40-45
• /
• 2009

본 논문에서는 사용자의 일상적인 동작 분석자료를 기반으로 실시간으로 사용자의 움직임 추정이 가능한 휴대형 센서 디바이스 및 활용 결과를 소개한다. 센서 디바이스는 3차원 가속센서와 GPS를 장착하고 있으며 센서 데이터 처리 및 움직임 추정을 위한 32비트 마이크로컨트롤러, 그리고 센서 데이터 및 추정결과를 전송하기 위한 블루투스 타입의 무선 통신 모듈을 포함한다. 완성된 디바이스는 50*47*14(mm)의 크기이며 리튬이온 소형 배터리 기준으로 연속 사용시 최대 10시간, 대기시간은 약 160시간 정도의 소형/저전력 형태로 구현되었다. 추정 가능한 사용자 움직임의 종류는 크게 3가지("서기", "달리기", "걷기")이며 피실험자군에 의한 동일 동작에 대한 가속센서 변화량을 학습하여 결정 트리 형식으로 사용자 움직임을 결정한다. 실험 결과 사용자 움직임 추정에 대한 정확도는 90% 이상인 것으로 확인되었다.

• 한국운동역학회지
• /
• 제21권2호
• /
• pp.253-258
• /
• 2011

The purpose of this study was to compare metabolic energy expenditure with the computed kinetic energy for different speeds of walking and running over the treadmill and to find the relevance for individual and group equation by performing a statistical analysis, Bland-Altman plot. Seven male subjects participated, and they were required to walk and run on the treadmill with the gas analyzer and triaxial accelerometer. Walking speeds were 3.0, 4.0, 5.0 and 6.0 km/h and running speeds were 7.0, 8.0 and 9.0 km/h respectively. Kinetic energy was calculated by the integration of acceleration data and compared with the metabolic energy measured by a gas analyzer. Correlation coefficients showed relatively good between the measured metabolic energy and the calculated kinetic energy. In addition, a dramatic increase in kinetic energy was also observed at the transition speed of walking and running, and two standard deviations in Bland-Altman plot, derived from the difference between measured and predicted values, were 1.14, 2.53, 2.93, 1.80, 2.80, 0.60 and 2.48 respectively. It was showed that there is no difference for methods of how to predict the kinetic energy expenditure for individual and group even though people had each different physical characteristic.

• 전자공학회논문지CI
• /
• 제45권3호
• /
• pp.135-141
• /
• 2008

본 논문은 3차원 가속 센서들과 장갑 형태로 제작한 RFID 리더기를 사용하여, 사용자의 신체 상태에 따른 동작 분석을 통해, 일상생활에서 사용자의 액티비티(Activity)를 자동으로 인식하는 새로운 방법을 제안한다. 두 개의 가속 센서로부터 획득한 움직임 정보로부터 선택 트리(Decision Tree) 방법을 통해 사용자의 5가지 자세 정보(Posture Information)를 구별하고, 손목에 장착된 가속 센서와 장갑 형태로 제작된 RFID 리더를 통해 인식한 객체와의 상호 작용을 통해서 도구를 사용하는 액티비티(Instrumental Activity)를 인식하는데 사용한다. 이를 위해, 객체 의존적인 손의 움직임을 학습에 의해 미리 5가지 카테고리로 분류한 후, 해당 객체와 인식된 움직임의 일치 여부를 확인한 후, 최종적으로 사용자의 신체 상태와 액티비티를 결정한다. 실험 결과에 의하면, 제안된 계층적 움직임 분석 방법은 20가지의 일상생활 액티비티들을 인식하는데 있어서 90%이상의 정확도를 보였다.

• 전기학회논문지
• /
• 제65권9호
• /
• pp.1557-1563
• /
• 2016

According to recent studies, poor sitting posture of the spine has been shown to lead to a variety of spinal disorders. For this reason, it is important to measure the sitting posture. We proposed a strategy for classification of sitting posture using machine learning. We retrieved acceleration data from single tri-axial accelerometer attached on the back of the subject's neck in 5-types of sitting posture. 6 subjects without any spinal disorder were participated in this experiment. Acceleration data were transformed to the feature vectors of principle component analysis. Support vector machine (SVM) and K-means clustering were used to classify sitting posture with the transformed feature vectors. To evaluate performance, we calculated the correct rate for each classification strategy. Although the correct rate of SVM in sitting back arch was lower than that of K-means clustering by 2.0%, SVM's correct rate was higher by 1.3%, 5.2%, 16.6%, 7.1% in a normal posture, sitting front arch, sitting cross-legged, sitting leaning right, respectively. In conclusion, the overall correction rates were 94.5% and 88.84% in SVM and K-means clustering respectively, which means that SVM have more advantage than K-means method for classification of sitting posture.

• 한국콘텐츠학회논문지
• /
• 제6권12호
• /
• pp.96-104
• /
• 2006

본 연구에서는, 심전도 송수신 장치의 개발을 위한 지그비(Zigbee) 기반 무선 센서 모듈과 PDA(Personal Digital Assistant)의 데이터 전송률과 전력 소비에 대하여 분석 하였다. 데이터 전송률은 패킷(Packet) 구조에 의존적이며, 패킷을 2개의 심전도 데이터와 1개의 3축 가속도 벡터로 구성하였을 때, 초당 300 샘플의 전송률을 나타내었다. 두 개의 AAA 전지를 직렬로 연결하여, 센서 모듈의 동작 시간은 평균적으로 28시간 이었다. PDA의 전력 소비는 화면의 ON/OFF 여부와 시리얼 포트의 사용 여부 및 패턴에 의존적임을 알 수 있었다. 이러한 응용에서, PDA 동작 시간은 평균적으로 5시간 정도임을 확인하였으며, 이때, PDA는 논 블로킹 모드로 시리얼 포트로부터 전송된 데이터를 수신 한다. 결론적으로, 본 연구에서 개발된 장치를 24 시간 홀터(Holter) 심전계로 응용할 경우, 센서 모듈의 전력 소비와 전송 속도에는 문제가 없었으나, PDA는 전력 소모율에 문제가 있으며 이는 해결되어야할 과제이다.

• 전기전자학회논문지
• /
• 제22권4호
• /
• pp.953-958
• /
• 2018

본 연구에서는 산업현장, 지하시설물의 밀폐공간에서 유해가스 및 생체신호를 동시에 검출이 가능한 휴대형 검출시스템을 개발하였다. 개발된 시스템은 가스검출용 센서모듈, 패치형 1채널 소형 ECG 센서, 3축가속도 검출센서용 모듈 및 통계분석용 시스템이다. 시스템모듈의 성능을 검증하기 위해 디지털해상도, 생체신호증폭도, 출력전압 및 초소형모듈의 크기로 평가하였다. 개발된 시스템의 성능결과 디지털해상도는 300(rps), 신호증폭이득은 500dB이상 성능을 가졌고, 심전도 모듈은 $50mm{\times}10mm{\times}10mm$로 제작되어 패치형으로 활용도를 높일 수 있다. 본 연구의 휴대용 가스검출기 및 패치용 심전도, 가속도검출기는 산업현장작업자의 실시간 감시용 IoT 기반 관리시스템으로 활용한다면 가치가 높을 것으로 생각된다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1609-1613
• /
• 2003

This research focused on the development of automatically exclusive production equipment of corrupad as changing manual system into automatic system to increase the output. Therefore the minimization of the problem of the rewinding mechanism with eccentric cantilever structure is key to the achievement of the high performance for automation production. Proto-type corrupad rewinding machine is manufactured after considering the effect of the rotational vibration and natural frequency of the structure of machine by using 3D design packages such as ADAMS and I-deas. For evaluating the performance of the proto-type machine, simulations of dynamic and static characteristics using 3D design packages, a series of modal tests by accelerometer and measurements of dynamic behavior by high-speed camera for rewinding part, were carried out. As a result, the proto-type machine was not affected with the rotational vibration. Whirling error of eccentric cantilever structure in driving is small. Therefore the machine developed is most suitable to produce corrupad automatically. However reinforcement of the structure in axial direction is required due to so vibration in that direction.

• Smart Structures and Systems
• /
• 제12권6호
• /
• pp.661-678
• /
• 2013

In this paper, a wireless sensing system for structural field evaluation and rating of bridges is presented. The system uses a wireless platform integrated with traditional analogue sensors including strain gages and accelerometers along with the operating software. A wireless vehicle position indicator is developed using a tri-axial accelerometer node that is mounted on the test vehicle, and was used for identifying the moving truck position during load testing. The developed software is capable of calculating the theoretical bridge rating factors based on AASHTO Load and Resistance Factor Rating specifications, and automatically produces the field adjustment factor through load testing data. The sensing system along with its application in bridge deck rating was successfully demonstrated on the Evansville Bridge in West Virginia. A finite element model was conducted for the test bridge, and was used to calculate the load distribution factors of the bridge deck after verifying its results using field data. A confirmation field test was conducted on the same bridge and its results varied by only 3% from the first test. The proposed wireless sensing system proved to be a reliable tool that overcomes multiple drawbacks of conventional wired sensing platforms designed for structural load evaluation of bridges.

• Journal of the Korean Wood Science and Technology
• /
• 제26권4호
• /
• pp.26-33
• /
• 1998

Acoustical properties of chestnut and paulownia woods have been determined in four film thicknesses of oriental lacquering and cashew varnishing on double surfaces of soundboard to elucidate effects of finishing. Accelerometer was attached to the specimen at one third position from one end, and specimen was hit by the impact hammer at one third position from opposite end. Data were processed by vibration analyzer. The ratio of axial-to-transverse sound velocity of untreated specimens of chestnut and paulownia were 3.25 and 5.34, respectively. Natural frequency, specific Young's modulus, acoustical coefficient, sound velocity, damping of sound radiation(DSR) and acoustical converting efficiency(ACE) decreased by oriental lacquering and cashew varnishing for both species. Damping of internal friction of chestnut decreased by oriental lacquering and cashew varnishing, but that of paulownia increased. Natural frequency. specific Young's modulus, acoustical coefficient, sound velocity, and DSR decreased with increased film thickness of both finishing materials. However, damping of internal friction and ACE showed irregular tendency with increased film thickness. Acoustical properties of cashew varnished chestnut specimen were better than those of oriental lacquered specimen. Acoustical properties of oriental lacquered paulownia specimen were better than those of cashew varnished specimen.