• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2138-2142
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• 2005

A wearable sensor system is proposed as a man-machine interface to control a device for walking assistance. The sensor system is composed of small sensors to detect the information about the user's body motion such as the activity level of skeletal muscles and the acceleration of each body parts. Each sensor includes a microcomputer and all the sensors are connected into a network by using the serial communication function of the microcomputer. The whole network is integrated into a belt made of soft fabric, thus, users can put on/off very easily. The sensor system is very reliable because of its decentralized network configuration. The body information obtained from the sensor system is used for controlling the assisting device to achieve a comfortable and an effective walking training.

• International Journal of Computer Science & Network Security
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• 제21권2호
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• pp.221-228
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• 2021

Recent improvements on the quality, fidelity and availability of biometric data have led to effective human physical activity detection (HPAD) in real time which adds significant value to applications such as human behavior identification, healthcare monitoring, and user authentication. Current approaches usually use machine-learning techniques for human physical activity recognition based on the data collected from wearable accelerometer sensor from a single wearable smart device on the user. However, collecting data from a single wearable smart device may not provide the complete user activity data as it is usually attached to only single part of the user's body. In addition, in case of the absence of the single sensor, then no data can be collected. Hence, in this paper, a continuous HPAD will be presented to effectively perform user activity detection with mobile service infrastructure using multiple wearable smart devices, namely smartphone and smartwatch placed in various locations on user's body for more accurate HPAD. A case study on a comprehensive dataset of classified human physical activities with our HAPD approach shows substantial improvement in HPAD accuracy.

• 대한임베디드공학회논문지
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• 제17권4호
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• pp.229-237
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• 2022

Motion recognition is very useful for implementing an intuitive HMI (Human-Machine Interface). In particular, hands are the body parts that can move most precisely with relatively small portion of energy. Thus hand motion has been used as an efficient communication interface with other persons or machines. In this paper, we design and implement a light-weight ANN (Artificial Neural Network)-based hand motion recognition using a state-of-the-art flex sensor. The proposed design consists of data collection from a wearable flex sensor, preprocessing filters, and a light-weight NN (Neural Network) classifier. For verifying the performance and functionality of the proposed design, we implement it on a low-end embedded device. Finally, our experiments and prototype implementation demonstrate that the accuracy of the proposed hand motion recognition achieves up to 98.7%.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.249-252
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• 2008

유비쿼터스 헬스케어에서의 착용형(Wearable) 생체신호 모니터링 시스템은 가슴 부착형, 손목시계형, 신발, 의복형 등과 같은 형태로 많은 연구들이 진행 중에 있으며, 본 논문에서는 가슴 부착형태의 인체 착용형 다중 생체신호 시스템을 설계하고, 다중 생체신호 모니터링 시스템을 위해 심전도와 3축 가속도 센서를 사용하여 심전도 신호 측정 및 신체 움직임에 따라 변화하는 값을 측정할 수 있도록 구현하였다. 구현한 시스템은 생체센서노드, 센서보드, 생체신호 수집을 위한 베이스스테이션 노드로 구성된다. 생체센서노드는 가슴 부착형으로 신체에 착용하여 사용자의 심전도와 가속도 신호를 계측하도록 설계하였으며, 서버 PC에 연결된 베이스스테이션 노드로 계측된 생체신호를 전송한다. 센서보드는 심전도와 가속도 신호를 측정하기 위한 센서로 구성되며, 생체센서노드와 일체형으로 장착이 가능하도록 설계하였다. 또한, 생체신호 수집을 위한 베이스스테이션 노드는 IEEE 802.15.4 무선통신을 통해 생체센서노드로부터 전송된 생체신호를 수집하여 그 수집된 생체신호를 실시간으로 서버 PC에 디스플레이가 가능하다. 본 논문에서 구현한 시스템을 통해 P, QRS, T파로 구성된 심전도 신호를 계측할 수 있었으며, 계측된 신호에서 심전도 신호의 파형 성분들이 나타남을 확인 할 수 있었다. 또한, 3축 가속도 센서에 의해 신체의 움직임에 따라 변화하는 x, y, z의 3축 가속도 출력 값을 얻을 수 있다.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제5권6호
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• pp.127-134
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• 2016

무선인체센서네트워크(WBSN: Wireless Body Sensor Network)은 일반적으로 무선인체네트워크(WBAN: Wireless Body Area Networks)라고도 불리는데, 일종의 무선센서네트워크(WSN: Wireless Sensor Network)의 응용 중에 하나로, 인간의 신체에 이식되거나 착용하는 형태의 감지노드들로 인체 가까이에 설치된다. WBSN에 설치된 각 노드로부터 측정된 데이터는 싱크 노드에서 인체 상태를 분석하기 위하여 사용되는데, 다른 무선센서네트워크 응용과 마찬가지로 노드와 싱크 노드는 서로 동기화되어야 한다. 무선센터네트워크에서 동작하는 여러시각 동기화 프로토콜이 제안되어왔으나 WBSN에 적용하기에는 부적합하다. 이 논문에서는 WBSN의 특성을 고려하여 새로운 시각 동기화 프로토콜을 제안한다. 제안한 프로토콜은 간단할뿐만 아니라 전력 소모가 작아 네트워크의 수명을 오랫동안 유지할 수 있게 한다. 제안 방안의 성능을 시뮬레이션을 통해 평가하였으며, WBSN에서 구현하기에 적합함을 보였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제11권1호
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• pp.23-32
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• 2011

A 40 fJ/c-s, 1 V, 10-bit SAR ADC is presented for energy constrained wearable body sensor network application. The proposed 10-bit dual sampling capacitive DAC topology reduces switching energy by 62% compared with 10-bit conventional SAR ADC. Also, it is more robust to capacitor mismatch than the conventional architecture due to its cancelling effect of each capacitive DAC. The proposed SAR ADC is fabricated in 0.18 ${\mu}m$ 1P6M CMOS technology and occupies 1.17 $mm^2$ including pads. It dissipates only 1.1 ${\mu}W$ with 1 V supply voltage while operating at 100 kS/s.

• Journal of Information Processing Systems
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• 제15권3호
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• pp.593-603
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• 2019

In wearable healthcare systems, sensor devices can be deployed in places around the human body such as the stomach, back, arms, and legs. The sensors use tiny batteries, which have limited resources, and old sensor batteries must be replaced with new batteries. It is difficult to deploy sensor devices directly into the human body. Therefore, instead of replacing sensor batteries, increasing the lifetime of sensor devices is more efficient. A transmission power control (TPC) algorithm is a representative technique to increase the lifetime of sensor devices. Sensor devices using a TPC algorithm control their transmission power level (TPL) to reduce battery energy consumption. The TPC algorithm operates on a closed-loop mechanism that consists of two parts, such as sensor and sink devices. Most previous research considered only the sink part of devices in the closed-loop. If we consider both the sensor and sink parts of a closed-loop mechanism, sensor devices reduce energy consumption more than previous systems that only consider the sensor part. In this paper, we propose a new approach to consider both the sensor and sink as part of a closed-loop mechanism for efficient energy management of sensor devices. Our proposed approach judges the current channel condition based on the values of various body sensors. If the current channel is not optimal, sensor devices maintain their current TPL without communication to save the sensor's batteries. Otherwise, they find an optimal TPL. To compare performance with other TPC algorithms, we implemented a TPC algorithm and embedded it into sensor devices. Our experimental results show that our new algorithm is better than other TPC algorithms, such as linear, binary, hybrid, and ATPC.

• 센서학회지
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• 제20권6호
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• pp.382-387
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• 2011

Whether a person is feeling sleepy or reasonably awake is important safety information in many areas, such as humans operating in traffic or in heavy industry. The changes of body signals have been mostly researched by looking at electroencephalogram(EEG) signals but more and more other medical signals are being examined. In our study, an electrocardiogram(ECG) signal is measured at a sampling rate of 100 Hz and used to try to distinguish the possible differences in signal between the two states: awake and drowsy. Practical tests are conducted using a wireless sensor node connected to a wearable ECG sensor, and an ECG signal is transmitted wirelessly to a base station connected to a server PC. Through the QRS complex in the ECG analysis it is possible to obtain much information that is helpful for diagnosing different types of cardiovascular disease. A program is made with MATLAB for digital signal filtering and graphing as well as recognizing the parts of the QRS complex within the signal. Drowsiness detection is performed by evaluating the R peaks, R-R interval, interval between R and S peaks and the duration of the QRS complex..

• ETRI Journal
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• 제41권4호
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• pp.452-464
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• 2019

The use of wireless body area networks (WBANs) in healthcare applications has made it convenient to monitor both health personnel and patient status continuously in real time through wearable wireless sensor nodes. However, the heterogeneous and complex network structure of WBANs has some disadvantages in terms of control and management. The software-defined network (SDN) approach is a promising technology that defines a new design and management approach for network communications. In order to create more flexible and dynamic network structures in WBANs, this study uses the SDN approach. For this, a WBAN architecture based on the SDN approach with a new energy-aware routing algorithm for healthcare architecture is proposed. To develop a more flexible architecture, a controller that manages all HUBs is designed. The proposed architecture is modeled using the Riverbed Modeler software for performance analysis. The simulation results show that the SDN-based structure meets the service quality requirements and shows superior performance in terms of energy consumption, throughput, successful transmission rate, and delay parameters according to the traditional routing approach.

• Journal of Communications and Networks
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• 제17권5호
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• pp.453-462
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• 2015

Body area networks (BANs) have emerged as an enabling technique for e-healthcare systems, which can be used to continuously and remotely monitor patients' health. In BANs, the data of a patient's vital body functions and movements can be collected by small wearable or implantable sensors and sent using shortrange wireless communication techniques. Due to the shared wireless medium between the sensors in BANs, it may be possible to have malicious attacks on e-healthcare systems. The security and privacy issues of BANs are becoming more and more important. To provide secure and correct association of a group of sensors with a patient and satisfy the requirements of data confidentiality and integrity in BANs, we propose a novel enhanced secure sensor association and key management protocol based on elliptic curve cryptography and hash chains. The authentication procedure and group key generation are very simple and efficient. Therefore, our protocol can be easily implemented in the power and resource constrained sensor nodes in BANs. From a comparison of results, furthermore, we can conclude that the proposed protocol dramatically reduces the computation and communication cost for the authentication and key derivation compared with previous protocols. We believe that our protocol is attractive in the application of BANs.