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A New Chest Compression Depth Feedback Algorithm for High-Quality CPR Based on Smartphone
Song, Yeongtak,Oh, Jaehoon,Chee, Youngjoon Mary Ann Liebert 2015 Telemedicine and e-health Vol.21 No.1
<P>Although many smartphone application (app) programs provide education and guidance for basic life support, they do not commonly provide feedback on the chest compression depth (CCD) and rate. The validation of its accuracy has not been reported to date. This study was a feasibility assessment of use of the smartphone as a CCD feedback device. In this study, we proposed the concept of a new real-time CCD estimation algorithm using a smartphone and evaluated the accuracy of the algorithm.</P>
Song, Yeongtak,Oh, Jaehoon,Chee, Youngjoon,Lim, Taeho,Kang, Hyunggoo,Cho, Youngsuk Canadian Anaesthetists' Society 2013 Canadian journal of anesthesia Vol.60 No.5
<P>This study is a feasibility assessment to determine the ability of novice users to utilize an infrared (IR) sensor stylet as a guide to position the tip of the endotracheal tube (ETT) 40 mm proximal to the carina in the swine trachea.</P>
전극 개수에 따른 근전도 기반 휴먼-컴퓨터 인터페이스의 정확도에 대한 연구
이슬비(Seulbi Lee),지영준(Youngjoon Chee) 한국HCI학회 2015 한국HCI학회 논문지 Vol.10 No.2
NUI(Natural User Interface)는 사용자의 자연스러운 동작이나 동작 시 발생하는 생체 신호를 해석하여 기계에 명령을 내리는 것을 말한다. 물리적인 변화가 있어야 사용이 가능한 가속도 센서나 영상 기반의 NUI와는 달리 특정 동작과 관련된 근육의 표면 근전도(surface Electromyogram, sEMG)를 측정하면 실제 움직임이 발생하지 않아도(isometric contraction) 동작 의도를 예측할 수 있다. 본 연구에서는 근전도 기반으로 손목 동작 의도를 분류할때 전극 개수에 따른 정확도를 확인하고, 키보드 등에 적용 가능한 인터페이스 기술을 제안한다. 손목의 동작 중 신전(extension, up), 굴곡(flexion, down), 외전(abduction, right), 내전(adduction, left)의 네 가지 동작 의도를 분류하는 실험을 진행하였다. 50ms 간격으로 계산된 제곱평균제곱근(Root Mean Square, RMS)을 특징으로 사용하였고, 동작 의도 인식을 위해 역전파 알고리즘으로 학습한 다층 퍼셉트론 분류기를 사용하였다. 전극 쌍의 개수를 네개(91.9%), 세 개(87.0%), 두 개(78.9%)로 줄여가며 정확도를 확인했다. 전극 쌍의 개수가 네 개에서 두 개로 줄었을 때 정확도는 약 13% 감소하였다. 두 쌍의 전극만 사용하는 경우의 분류 정확도를 높이기 위하여 직전의 RMS를 특징에 추가하였다. 150 ms 이전까지의 정보를 사용하였을 때, 분류 정확도가 78.9%에서 83.6%로 4.6% 증가하였다. 전극 쌍의 개수가 감소함에 따라 정확도는 감소하였지만, 이전 데이터를 함께 사용한 경우 부분적으로 증가 시킬 수 있음을 확인하였다. NUI (Natural User Interface) system interprets the user’s natural movement or the signals from human body to the machine. sEMG (surface electromyogram) can be observed when there is any effort in muscle even without actual movement, which is impossible with camera and accelerometer based NUI system. In sEMG based movement recognition system, the minimal number of electrodes is preferred to minimize the inconvenience. We analyzed the decrease in recognition accuracy as decreasing the number of electrodes. For the four kinds of movement intention without movement, extension (up), flexion (down), abduction (right), and adduction (left), the multilayer perceptron classifier was used with the features of RMS (Root Mean Square) from sEMG. The classification accuracy was 91.9% in four channels, 87.0% in three channels, and 78.9% in two channels. To increase the accuracy in two channels of sEMG, RMSs from previous time epoch (50-200 ms) were used in addition. With the RMSs from 150 ms, the accuracy was increased from 78.9% to 83.6%. The decrease in accuracy with minimal number of electrodes could be compensated partly by utilizing more features in previous RMSs.
서영수(Young Soo Suh),지영준(Youngjoon Chee) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.5
A foot motion is estimated using an inertial sensor unit, which is installed on a shoe. The inertial sensor unit consists of 3 axis accelerometer and 3 axis gyroscopes. Attitude and position of a foot are estimated using an inertial navigation algorithm. To increase estimation performance, a smoother is used, where the smoother employs a forward and backward filter structure. An indirect Kalman filter is used as a forward filter and backward filter. A new combining algorithm for the smoother is proposed to combine a forward indirect Kalman filter and a backward indirect Kalman filter. Through experiments, the estimation performance of the proposed smoother is verified.
웨어러블 센서를 이용한 일상생활중 머리-목 자세 측정 시스템
이재현,지영준,배지은,김하선,김영훈,Lee, Jaehyun,Chee, Youngjoon,Bae, Jieun,Kim, Haseon,Kim, Younghoon 대한의용생체공학회 2016 의공학회지 Vol.37 No.3
The neck pain is fairly common occurance. Forward head posture and text neck are poor postures which may be related with neck pain but the evidence is not enough. We developed the wearable sensor which can assess the head & neck posture in daily life. Microprocessor, Bluetooth low energy, and 3-axis accelerometer, rechargeable battery and vibratior for reminding are used to implement the wearable sensor. Real-time algorithm to parameterize the posture for one epoch is implemented which classifies the posture in the epoch into three classed; dynamic, static_good posture, and static_poor posture. Also the algorithm makes reminding to its wearer to give them the prolonged poor posture is detected. The mean error of measurement was 1.2 degree. The correlation coefficient between neck angle and craniovertebral angle was 0.9 or higher in all cases. With the pilot study on text neck syndrome was also quatified. Average of neck angle were 74.3 degree during the listening in the classroom and 57.8 degree during the smartphoning. Using the wearable sensor suggested, the poor postures of forward head posture and neck neck can be detected in real-time which can remind the wearer according to his/her setting.
A Measurement System for Rounded Shoulder Posture using a Wearable Stretch Sensor
Nguyen, Manh Thang,Dang, Quoc Khanh,Kim, Younghoon,Chee, Youngjoon The Korean Society of Medical and Biological Engin 2018 의공학회지 Vol.39 No.1
In this paper, we present a wearable measurement system for monitoring rounded shoulders. The system contains a shoulder correction band and a stretch sensor that can correct and measure shoulder posture, respectively. The capacitance of the stretch sensor changes linearly according to changes in the shoulders. To verify measurement, a motion analysis system was used as the reference to compare the change in the rounded angles of the shoulders and the change in the stretch sensor's capacitance. The results indicated that there is a high correlation between the two changes and the system can be used as a monitoring device for rounded shoulders.
Digital recording system of sphygmomanometry.
Lee, Jongshill,Park, Daekyu,Oh, Hongsic,Kim, Inyoung,Shen, Dongfan,Chee, Youngjoon Rapid Science Publishers ; Rapid Science Publisher 2009 Blood pressure monitoring Vol.14 No.2
<P>OBJECTIVES: Validation of blood pressure measurement devices is always difficult because the gold standard method depends on the observer's manual assessment. To improve the assessment algorithm in automatic blood pressure measurement devices, knowing the reference blood pressure values and analyzing various data are always necessary. A digital system to record Korotkoff sound and cuff pressure is suggested. METHODS: The recording system consists of cuff, microphone, amplifier, and all the components of an oscillometric measurement device, which enable the collection of various data from patients. After collecting the data, the browsing software can playback the recorded sound and pressure variation on a computer. RESULTS: The system records the Korotkoff sound faithfully. The sound can be played with sound card on a personal computer. Cuff pressure can also be displayed with Korotkoff sound at the same time. With this playback software, the observer can assess systolic blood pressure and diastolic blood pressure . The observer can listen again and discuss with others when the decision is not clear. CONCLUSION: The digital recording system of sphygmomanometry can be used for validation of blood pressure measurement devices, collecting of oscillometric data for research, and educating the students who learn blood pressure measurement.</P>