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PTC(Positive Temperature Coefficient)발열체를 이용한 온열 뜸의 개발
문기욱(Ki-wook Moon),이충회(Chung-hoe Lee),이보환(Bo-whan Lee),허현(Hyun Heo) 대한전기학회 2010 정보 및 제어 심포지엄 논문집 Vol.2010 No.10
본 연구의 목적은 PTC 발열체를 이용한 온열 뜸을 개발 하는 것이다. PTC 발열체는 고유저항이 증가함에 따라 온도가 상승하며, 회로에 과전류가 유입되면 정상적인 작동을 하던 회로의 저항이 급격히 증가하면서 회로에 흐르는 전류를 제한하여 기기를 보호하는 기능을 수행한다. 또한 인체에 무해하다. 이 발열체를 쉽게 부착하기 위하여 실리콘 부항을 사용하였다. 12V 전원을 인가하였을 경우, 측정된 최대 온도는 86℃. 평균온도는 47±l2℃였다. 장시간 지속하였을 경우에도 최대 설정 온도 이상으로 발열하지 않기 때문에 안전하다. 따라서 본 연구에서 제안하는 시스템은 뜸의 효과를 구현할 수 있다.
FES보행중의 피드백제어를 위한 관절 각도계측 시스템 개발
文基旭(Ki-Wook MOON),金哲承(Chul-Seung KIM),金智源(김지원),李載浩(Jea-Ho Lee),權柳利(Yu-Ri Kwon),姜同院(Dong-Won Kang),姜坤(Gon Khang),金耀翰(Yo-Han Kim),嚴光文(Gwang-Moon EOM) 대한전기학회 2009 전기학회논문지 Vol.58 No.1
The purpose of this study is to develop a minimally constraint joint angle measurement system for the feedback control of FES (functional electrical stimulation) locomotion. Feedback control is desirable for the efficient FES locomotion, however, the simple on-off control schemes are mainly used in clinic because the currently available angle measurement systems are heavily constraint or cosmetically poor. We designed a new angle measurement system consisting of a magnet and magnetic sensors located below and above the ankle joint, respectively, in the rear side of ipsilateral leg. Two magnetic sensors are arranged so that the sensing axes are perpendicular each other. Multiple positions of sensors attachment on the shank part of the ankle joint model and also human ankle joint were selected and the accuracy of the measured angle at each position was investigated. The reference ankle joint angle was measured by potentiometer and motion capture system. The ankle joint angle was determined from the fitting curve of the reference angle and magnetic flux density relationship. The errors of the measured angle were calculated at each sensor position for the ankle range of motion (ROM) -20~15 degrees (dorsiflexion as positive) which covers the ankle ROM of both stroke patients and normal subjects during locomotion. The error was the smallest with the sensor at the position! which was the nearest position to the ankle joint In case of human experiment, the RMS (root mean square) errors were 0.51±1.78(0.31~0.64) degrees and the maximum errors were 1.19±0.46(0.68~1.58) degrees. The proposed system is less constraint and cosmetically better than the existing angle measurement system because the wires are not needed.
김철승,문기욱,권정훈,엄광문,Kim, Chul-Seung,Moon, Ki-Wook,Kwon, Jung-Hoon,Eom, Gwang-Moon 대한의용생체공학회 2006 의공학회지 Vol.27 No.6
The purpose of this work is to predict the systolic blood pressure (BP) during exercise from pulse transit time (PTT) for warning of possible danger. PTT was calculated as the time between R-peak of ECG and the peak of differential photoplethysmograph (PPG). For the PTT-BP model, we used regress equations from previous studies and 3 kinds of new models combining linear and nonlinear regress equation. The model parameters were estimated with the data measured under low to middle intensity exercise, and then was tested with the data measured under high intensity exercise. Predicted BP values after high intensity exercise were compared with those measured by cuff-type sphygmomanometer. The results showed that the error between measured and predicted values were acceptable for the monitoring BP. We tested PTT-BP models 1 month after the identification without further calibration. Models could predict the BP and the errors between measured and predicted BP were about 5mmHg. The suggested system is expected to be helpful in recognizing any danger during exercise.
金哲承(Chul-Seung Kim),文基旭(Ki-Wook Moon),嚴光文(Gwang-Moon Eom),李受映(Soo-Young Lee) 대한전기학회 2007 전기학회논문지 Vol.56 No.4
The purpose of this work is to develop a measurement system of the pendulum test with minimal restriction of experimental environment and little influence of noise. In this work, we developed a vision system without any line between markers and a camera. The system performance is little influenced by the experimental environment, if light are sufficient to recognize markers. For the validation of the system, we compared knee joint angle trajectories measured by the developed system and by the magnetic sensor system during the nominal pendulum test and the maximum speed voluntary knee joint rotation. The joint angle trajectories of the developed system during both tests matched well with those of the magnetic system. Therefore, we suggest the vision system as an alternative to the previous systems with limited practicality for the pendulum test.
〈속보논문〉 PTT를 이용한 운동 중 혈압 예측을 위한 Local과 Global Fitting의 비교
金哲承(Chul-Seung KIM),文基旭(Ki-Wook MOON),嚴光文(Gwang-Moon EOM) 대한전기학회 2007 전기학회논문지 Vol.56 No.12
The purpose of this work is to compare the local fitting and global fitting approaches while applying regression model to the PTT-BP data for the prediction of exercise blood pressures. We used linear and nonlinear regression models to represent the PTT-BP relationship during exercise. PTT-BP data were acquired both under resting state and also after cycling exercise with several load conditions. PTT was calculated as the time between R-peak of ECG and the peak of differential photo-plethysmogram. For the identification of the regression models, we used local fitting which used only the resting state data and global fitting which used the whole region of data including exercise BP. The results showed that the global fitting was superior to the local fitting in terms of the coefficient of determination and the RMS (root mean square) error between the experimental and estimated BP. The nonlinear regression model which used global fitting showed slightly better performance than the linear one (no significant difference). We confirmed that the wide-range of data is required for the regression model to appropriately predict the exercise BP.
정적 서기와 쪼그려 앉았다 서기 동작에서 고령자남녀의 자세 동요 비교
金智源(Ji-Won Kim),金多慧(Da-Hye Kim),文基旭(Ki-Wook Moon),嚴光文(Gwang-Moon Eom),南貞淑(Jung-Sook Nam),金耀翰(Yo-Han Kim),洪廷和(Jeong-Hwa Hong),朴炳奎(Bung-Kyu Park) 대한전기학회 2008 전기학회논문지 Vol.57 No.11
In this paper, COP (center of pressure) during quiet standing and squat-and-stand movement was analyzed to compare the postural control of young and elderly subjects with special interest in the elderly females who were reported to have higher fall rate than the elderly males. Subjects include the young subjects (10 males: 21.8±2.6yrs, 10 females: 20.4±0.3yrs) and the elderly subjects (8 males: 75.5±4yrs, 8 females: 72.3±3.5yrs). Analysis parameters were the mean of the distance between the instantaneous COP and the average COP (COP distance) and the mean of the COP movement velocity (COP velocity) in both AP (anterio-posterior) and ML (medio-lateral) directions. During quiet standing, the COP distance in ML direction of elderly females was significantly greater than that of elderly males and the COP velocity of elderly females in both ML and AP direction were significantly greater than those of all the other groups. During squat-and-stand movement, the COP distance of elderly females was not significantly different with that of the elderly males. However, the COP velocity of elderly females was significantly greater than that of all the other groups. The large lateral weight shift (COP distance) of elderly females during quiet standing may explain their greater fall rate. However, this does not apply to squat-and-stand movement. In contrast, COP velocity results show that the elderly females' COP is rapidly trembling compared to that of elderly males during both quiet standing and squat-and-stand movement. This results suggest that rapid trembling or postural sway may reflect the reduced postural control ability and the risk of falling.
고령자 남녀와 20대 남녀에 있어서 다양한 등속수축중 최대 모멘트의 비교
金智源(Ji-Won Kim),金相佑(Sang-Woo Kim),文基旭(Ki-Wook Moon),嚴光文(Gwang-Moon Eom),李泳揆(Young-Gyu Lee),南貞淑(Jung-Sook Nam),朴寬龍(Kwan-Yong Park),金耀翰(Yo-Han Kim),洪廷和(Jeong-Hwa Hong),朴炳奎(Bung-Kyu Park) 대한전기학회 2008 전기학회논문지 Vol.57 No.10
In this paper, we investigated the maximum ankle joint plantarflexion moment (MPM) of young and elderly subjects during various modes of isokinetic contractions with special interest in the elderly females who were reported to have higher fall rate than the elderly males. Subjects include the young subjects (14 males: 22.7±2.5yrs, 13 females: 20.5±1.3yrs) and the elderly subjects (17 males: 65.8±10.5yrs, 26 females: 71.4±5.2yrs). The MPM was normalized by each subject's body weight. The MPM of elderly females was the weakest among the groups, particularly, at the eccentric contractions. The male-to-female ratio of MPM was greater in the elderly than in the young and the young-to-elderly ratio of MPM was greater in female than in male, both during the eccentric contractions. The result suggests that the decreased muscle force per body weight, especially at the eccentric contraction, may be one reason for the more frequent fall of the elderly female than the elderly male.
〈속보논문〉 가속도계를 이용한 마비환자의 보행이벤트 검출
孔世鎭(Se-Jin KONG),金哲承(Chul-Seung KIM),文基旭(Ki-Wook MOON),嚴光文(Gwang-Moon EOM),卓?來(Gye-Rae TACK),金敬燮(Kyeong-Seop KIM),李定桓(Jeong-Whan LEE),李永熙(Young-Hee LEE) 대한전기학회 2007 전기학회논문지 Vol.56 No.5
The purpose of this study is to develop a practical gait-event detection system which is necessary for the FES (functional electrical stimulation) control of locomotion in paralyzed patients. The system is comprised of a sensor board and an event recognition algorithm. We focused on the practicality improvement of the system through 1) using accelerometer to get the angle of shank and dispensing with the foot-switches having limitation in indoor or barefoot usage and 2) using a rule-base instead of threshold to determine the heel-off/heel-strike events corresponding the stimulation on/off timing. The sensor signals are transmitted through RF communication and gait-events was detected using the peaks in shank angle. The system could detect two critical gait-events in all five paralyzed patients. The standard deviation of the gait events time from the peaks were smaller when 1.5㎐ cutoff frequency was used in the derivation of the shank angle from the acceleration signals.