• 한국운동역학회지
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• 제21권4호
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• pp.495-501
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• 2011

The purpose of this study was to develop the inertial sensor module system to detect gait event using single angular rate sensor(gyroscope), and evaluate the accuracy of this system. This sensor module is attached at the heel and gait events such as heel strike, foot flat, heel off, toe off are detected by using proposed automatic event detection algorithm. The developed algorithm detect characteristics of pitch data of the gyroscope to find gait event. To evaluate the accuracy of system, 3D motion capture system was used and synchronized with sensor module system for comparison of gait event timings. In experiment, 6 subjects performed 5 trials level walking with 3 different conditions such as slow, preferred and fast. Results showed that gait event timings by sensor module system are similar to that by kinematic data, because maximum absolute errors were under 37.4msec regardless of gait velocity. Therefore, this system can be used to detect gait events. Although this system has advantages of small, light weight, long-term monitoring and high accuracy, it is necessary to improve the system to get other gait information such as gait velocity, stride length, step width and joint angles.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.187-188
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• 1998

A low cost, low power, portable cardiac event recorder as a tether-free biological signal processor was developed. Dual channel ECG signals are sampled at 128Hz in 12 bits resolution. Sampled data are continuously recorded in a circular buffer. If event button is pressed, 2 minutes data before and after the event are recorded in 512 Kbyte SRAM. Total 11 events can be recorded. Data can be transferred to PC through RS-232 protocol. It operates for two months by a half AA size 3.6V Lithium battery. The system size is $55\times55\times13[mm^3]$.

• 대한의용생체공학회:의공학회지
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• 제29권6호
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• pp.443-450
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• 2008

The purpose of this study is to measure both ECG and BCG(Ballistocariograph) signal of a subject on moving or resting wheelchair and detect the heart rate and respiratory rate and transmit an event message to remote server on emergent situation. To acquire ECG and BCG data, amplifier circuits were composed to be suitable for their characteristics. The output signals were converted to digital data and stored in bio-signal archiving media(SD card). CDMA module was used to transmit the event data on ECG electrode detachment and the received data was monitored by the developed C# application program. 5 volunteers participated in the experiment to evaluate the validity of the developed device. When the event occurs in each subject, 48 Kbyte data, stored for 32 seconds from that point, was transmitted to remote server through CDMA cellular phone network correctly. The received data of ECG, BCG, and 3-axial acceleration could be archived in server and the heart rate and respiratory rate could be measured and analyzed. The developed device in this study could acquire the ECG and BCG data of subjects on wheelchair simultaneously and measure their heart rate and respiratory rate. In addition, event data was verified to be transmitted to remote server without any errors.

• 한국문헌정보학회지
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• 제51권4호
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• pp.77-97
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• 2017

최근 생의학 분야의 학술 문헌이 기하급수적으로 급증함에 따라 관련 분야 연구자들은 선행 연구 및 연구 동향 파악에 어려움을 겪고 있다. 이에 효율적인 선행 연구 및 연구 동향 파악을 위한 정보 추출 기술이 요구되며, 학술 문헌의 정보 추출을 위한 개체인식 및 개체 간의 생의학 이벤트 추출 연구가 활발히 진행되고 있다. 본 연구는 이에 심층 학습(Deep Learning)의 기법 중 하나인 컨볼루션 네트워크(Convolutional Neural Networks, CNN) 모델을 기반으로 이벤트 내의 개체 유형 정보의 적용 위치와 함께, 이벤트 식별 및 분류를 고려하여 총 8가지의 모델을 구성하여 실험하였다. 실험 결과, 본 연구에서 제안하는 모델 중 최고성능을 보인 개체 유형 완전연결 모델이 이벤트 분류 실험에서 F-점수 72.09%의 높은 성능을 보였으나, 이벤트 추출 실험에서는 학습 컬렉션의 불균형 문제 및 이벤트 식별 모델의 성능 저조 등으로 인하여 F-점수 21.81%의 비교적 저조한 성능을 보였다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2006년도 제33회 추계학술대회 발표논문집
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• pp.45-45
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• 2006

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2003년도 제8차 학술대회 초록집
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• pp.81-81
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• 2003

This event-related fMRI study was to further our understanding about how different brain regions could contribute to effective access of specific information related to cognitive process and shows the different response of brain regions involved in recognition of familiar faces compared to unfamiliar faces and repetition effect.

• 대한의용생체공학회:의공학회지
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• 제30권4호
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• pp.306-310
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• 2009

The purpose of this study is to observe the change in gamma-band cortical activities (GBAs) due to task difficulty. Event-related potential and gamma-band activity were investigated using electroencephalograms recorded during auditory oddball tasks with two difficulty levels. For more difficult task, the amplitude of P300 decreased and the peak latency of P300 was delayed significantly compared to easier task. The induced GBA decreased considerably during the P300 latency period and the peak latency of the induced GBA was delayed for more difficult task. The results imply that the difficulty-related change in cortical information processing may be implemented as a change in the strength of local neuronal association.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.451-458
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• 2012

The voluntary EMG (vEMG) signal from electrically stimulated muscle is very useful for feedback control in functional electrical stimulation. However, the recorded EMG signal from surface electrodes has unwanted stimulation artifact and M-wave as well as vEMG. Here, we propose an event-synchronous adaptive digital filter for the suppression of stimulation artifact and M-wave in this application. The proposed method requires a simple experimental setup that does not require extra hardware connections to obtain the reference signals of adaptive digital filter. For evaluating the efficiency of this proposed method, the filter was tested and compared with a least square (LS) algorithm using previously measured data. We conclude that the cancellation of both primary and residual stimulation artifacts is enhanced with an event-synchronous adaptive digital filter and shows promise for clinical application to rehabilitate paretic limbs. Moreover because this algorithm is far simpler than the LS algorithm, it is portable and ready for real-time application.

• 한국운동역학회지
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• 제19권1호
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• pp.159-166
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• 2009

본 연구의 목적은 실외 보행 실험 시 사용하기에 간편한 가속도계를 이용하여 보행 이벤트를 자동으로 검출하는 알고리즘을 개발하고 검증하는 것이다. 개발된 알고리즘은 신발의 발등에 부착된 3축 가속도계의 가속도의 총합과 보행 진행 방향(x축) 가속도를 이용하였다. 가속도 총합은 착지 시점의 검출에, x축 가속도는 이지 시점의 검출에 각각 사용되었다. 7명의 피험자가 느린 보행 속도 선호 보행 속도 빠른 보행 속도로 보행 실험을 수행하였고, 개발된 알고리즘의 검증을 위해 지면반력기를 포함한 3차원동작분석시스템과 동시에 실시되었다. 지면반력기를 이용한 보행 시점을 기준으로, 기존에 발표된 동작 자료만을 이용한 알고리즘을 통하여 얻어진 보행 시점도 함께 비교 하였다. 그 결과, 고안된 알고리즘의 정확도는 지면반력기를 이용한 값에 평균, 착지시점은 $22.33{\pm}17.45ms$, 이지시점은 $26.82{\pm}14.78ms$의 차이가 났고, 그 오차의 패턴이 일관적으로 20ms가량 먼저 검출되는 경향이 있었다. 일반적으로 트레드밀 실험에서 많이 사용되는 동작데이터를 통한 보행 시점의 비교에서도 크게 차이를 보이지 않았다. 그러므로 개발된 알고리즘은 실외 실험의 보행 시점 검출에 이용할 수 있을 것으로 판단된다. 추후 연구로는 현재의 가속도계만으로 보행 시점뿐 만아니라, 중력가속도 성분을 제거하여 보행 공간변인의 추출이 필요할 것이다.

• 대한의용생체공학회:의공학회지
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• 제29권4호
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• pp.295-301
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• 2008

A wireless 3 channel ECG monitoring system was developed so that it could monitor the health and movement state during subject's daily life. The developed system consists of a wireless biomedical signal acquisition device, a personal healthcare server, and a remote medical server. Three experiments were performed to evaluate the accuracy, reliability and operability, applicability during daily life of the developed device. First, ECG signals were measured using the developed device and commercial reference device during sitting and marking time and compared to verify the accuracy of R-R intervals. Second, the reliable data transmission to remote server was verified on two types of simulated emergency event using patient simulator. Third, during five types of motion in daily life, the accuracy of data transmission to remote server using CDMA network was verified on two types of event occurring. By acquiring and comparing subject's biomedical signal and motion signal, the accuracy, reliability and operability, applicability during daily life of the developed device were verified. In addition, PDA-phone based wireless system enabled subject to be monitored without any constraints. Therefore, the developed system is expected to be applicable for monitoring the aged and chronic diseased people and giving first-aid in emergency.