• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.125-131
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• 2002

Respiratory air flow rate is necessarily measured for the pulmonary function evaluation. The currently used devices are exposed to the problems of measurement reliability and cross-patient infection. The present study introduced a new technique which converted the bidirectional air flow rate into averaged dynamic pressure based on the famous Bernoulli's energy conservation principle. Single use plastic sensing element was assembled within the flow tube(mouth piece) made of paper, which was named "functional single use flow tube". Experiment demonstrated only ${\pm}1.5%$ relative error in the standard 3L volume measurement procedure well within the error limit suggested by the American Thoracic Society(ATS). Disposable use design completely eliminated cross-patient infection. The present device is best useful and safe for clinical respiratory air flow measurement such as spirometry.

• 전자공학회논문지 IE
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• v.43 no.4
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• pp.28-36
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• 2006

In this paper, an algorithm to classify the 4 motions of arm and a control system to position control the prosthesis are studied. To classify the 4 motions, we use flex sensors which is electrical resistance type sensor that can measure warp of muscle. The flex sensors are attached to the biceps brchii muscle and coracobrachialis muscle and the sensor signals are passed the sensing system. 4 motion of the forearm - flexion and extension, the pronation and supination are classified from this. Also position of forearm is measured from the classified signals. Finally, A two D.O.F prosthesis arm with RC servo-motor is designed to verify the validity of the algorithm. At this time, fuzzy controller is used to reduce the position error by rotary inertia and noise. From the experiment, the position error had occurred within about 5 degree.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.470-473
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• 2021

In this study, we developed the biometric ultrasound transducer, residual thickness measurement algorithm and optimized ultrasound operation methods to diagnose precise conditions of implanted medical prosthetic material inserted during total hip artificial joint replacement. In detail, ultrasound transducers having 8 MHz and 20 MHz center frequencies with similar sensitivity and bandwidth were fabricated to measure various thicknesses of commercial polyethylene-based artificial hip liners, resulting in a comparative analysis of signal-to-noise ratio and axial resolution to conduct an optimization study of ultrasound operations in vivo.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.503-514
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• 2013

Mobile Healthcare is a new type of health care services for managing health and life irrespective of time and space by uniting IT and BT. For this service bio-signal measurement using WBAN, and data analysis and monitoring technologies based on mobile devices are essential. Generally, however, mobile application has low compatibility because of the features of mobile platform, we have to redevelop it to support the corresponding platform. In this paper we introduce a Mobile Healthcare System which can function as gateway and monitoring based on hybrid app to create ubiquitous healthcare monitoring system compatible with various mobile devices by overcoming the difference of platforms. The proposed system consists of sensor composition part, monitoring composition part, and server composition part.

• Journal of the Korean Society of Radiology
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• v.1 no.1
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• pp.39-44
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• 2007

In this study, wireless measurement technique for human motion was developed to monitor movement disorder patients during their daily life. MICA, TinyOS, and nesC, developed by UC Berkeley, were used as wireless sensor, its software platform, and programming language. The human motion data, generated by two axial accelerometer(ADXL202) was transmitted to PDA(iPaq3630) by 916Mhz short range communication chip(TR1000). It could be stored at PDA by simple Windows CE programming. To test the developed device, it was attached at human chest and the acquired data was shown as a graph during his motion of sitting, standing, and lying. The result showed that human motion could be logged without any hooking and constraints. Therefore, this device can be used to monitor patient's movement disorder and activity of daily life(ADL).

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.01a
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• pp.125-128
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• 2016

본 논문에서는 다중 생체계측 장비를 CMCIS(Central Monitoring and Cardiology Information System) 기반의 통합 시스템에 연동하기 위한 MDEC(Medical Device Exchange Communication)의 설계 및 구현을 소개한다. MDEC은 6종의 계층장비의 신호를 받아 각 서버로 데이터를 전송할 수 있도록 설계하고 Linux OS을 포팅 하였다. 각 장비별 프로토콜에 대해 최소화된 기본 프로토콜을 정의하고 통신방법에 따라 UART 포트 혹은 USB 포트를 생체정보의 물리적 입력장치로 사용하였다. 호스트 서버와는 유무선 LAN울 통해 정보를 전달할 수 있게 하드웨어를 설계하였다. 본 연구의 결과는 CMCIS 기반의 통합 시스템을 구축하는 기반기술로 향후 효율적 의료서비스에 기여할 것으로 사료된다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.166-166
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• 2017

모돈의 건강 상태를 정량 지수화 하기 위한 연구를 수행 중이다. 지제이상, 섭식 불량, 수면 패턴 등의 운동 특성 분석을 위하여 복수의 초음파 센서를 이용하였다. 시계열 계측 신호를 분석하여 정량 지수화를 수행하는 과정에서 주파수 도메인 분석을 시도하였다. 이 과정에서 주파수 도메인의 분해능에 따른 편차 극복을 위한 비선형 모델링을 수행하였다. 또한 인접한 시계열 데이터 구간 간의 상관성 분석이 가능하면 대용량 데이터의 실시간 처리로 인한 지연 시간 극복 및 기대되는 예후에 대한 조기 진단이 가능할 것이다. 본 연구에서는 구글에서 제공하는 Tensorflow와 NVIDIA에서 제공하는 CUDA 엔진을 동시 적용한 심층 학습 시스템을 이용하였다. 전 처리를 위하여 주파수 분해능 (2분, 3분, 5분, 7분, 11분, 13분, 17분, 19분)에 따른 데이터 집합을 1단계로 두고, 상위 10 순위 안에 드는 파워 스펙트럼 밀도의 크기를 2단계로 하여, 총 2~10개의 입력 노드를 순차적으로 선정하였고, 동일한 방식으로 인접한 시계열의 파워 스펙터럼 밀도를 순위를 변화시켜 지정하였다. 대표적인 심층학습 모델인 Softmax regression with a multilayer convolutional network를 이용하여 Recursive feature selection 경우의 수를 $8{\times}9{\times}9$로 총 648 가지 선정하고, Epoch는 10,000회로 지정하였다. Calibration 모델링의 경우 Cost function이 10% 이하인 경우 해당 경우의 학습을 중단하였으며, 모델 간 상호 교차 검증을 수행하기 위하여 $_8C_2{\times}_8C_2{\times}_8C_2$ 경우의 수에 대한 Verification test를 수행하였다. Calibration 과정 상 모든 경우에 대하여 10% 이하의 Cost function 값을 보였으나, 검증 테스트 과정에서 모든 경우에 대하여 $r^2$ < 0.5 인 결정 계수 값이 나타났다. 단적으로 심층학습 모델의 과도한 적합(Over fitting) 방식의 한계를 보인 것이라 판단할 수 있다. 적합한 Feature selection 및 심층 학습 모델에 대한 지속적이고 추가적인 고려를 통해 과도적합을 해소함과 동시에 실효적이고 활용 가능한 Classification을 위한 입, 출력 노드 단의 전후 Indexing, Quantization에 대한 고려가 필요할 것이다. 이를 통해 모돈 생체 정보 정량화를 위한 지능형 현장 진단 기술 연구를 지속할 것이다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.130-137
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• 2013

This paper presents analog front-end(AFE) circuits for bio-potential measurement. The proposed AFE is composed of IA(instrument amplifier), BPF(band-pass filter), VGA(variable gain amplifier) and SAR(successive approximation register) type ADC. The low gm(LGM) circuits with current division technique and Miller capacitance with high gain amplifier enable IA to implement on-chip AC-coupling without external passive components. Spilt capacitor array with capacitor division technique and asynchronous control make the 12-b ADC with low power consumption and small die area. The total current consumption of proposed AFE is 6.3uA at 1.8V.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.323-335
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• 2015

Mobile healthcare is a fusion of information technology and biotechnology and is a new type of health management service to keep people's health at anytime and anywhere without regard to time and space. The WBAN(Wireless Body Area Network) technology that collects bio signals and the data analysis and monitoring technology using mobile devices are essential for serving mobile healthcare. WBAN consisting of users with mobile devices meet another WBAN during movement, WBANs transmit data to the other media. Because of WBAN conflict, several nodes transmit data in same time slot so a collision will occur, resulting in the data transmission being failed and need more energy for re-transmission. In this thesis, we proposed a MAC protocol for WBAN with mobility to solve these problems. First, we proposed a superframe structure for WBAN. The proposed superframe consists of a TDMA(Time Division Muliple Access) based contention access phase with which a node can transmit data in its own time slot and a contention phase using CSMA/CA algorithm. Second, we proposed a network merging algorithm for conflicting WBAN based on the proposed MAC protocol. When a WBAN with mobility conflicts with other WBAN, data frame collision is reduced through network reestablishment. Simulations are performed using a Castalia based on the OMNeT++ network simulation framework to estimate the performance of the proposed superframe and algorithms. We estimated the performance of WBAN based on the proposed MAC protocol by comparing the performance of the WBAN based on IEEE 802.15.6. Performance evaluation results show that the packet transmission success rate and energy efficiency are improved by reducing the probability of collision using the proposed MAC protocol.