• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.10
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• pp.494-501
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• 2001

In this study, the effects of vascular parameter changes and electrodes on VOP measurement based on IPG were simulated mathematically. For the evaluation of the effects of hemodynamic changes on VOP, a mathematical model, which consists of cardiovascular system model and venous occlusion model, was developed and the model solution representing the blood flow and pressure in measuring point was found by 2nd order Runge-Kutta method. And, with sensitivity coefficients obtained from finite element solution of electric field in measuring point, the effects of electrode system on measurement were evaluated. As increasing the resistance, the venous capacitance was not changed but the venous outflows were decreased and the decreased compliance reduced the venous capacitance. And, for several configurations of round electrodes and band electrodes, the sensitivity coefficients were computed using the electric field distribution along deep vein. In conclusion, the proposed mathematical cardiovascular model could be applied to the simulation study on the effects of hemodynamic parameters on DVT diagnosis with IPG. And, also the sensitivity coefficients could provide effective electrode configuration for exact measurement of VOP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2159-2164
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• 2008

Ubiquitous healthcare system is system that monitors and manages user's health information, and most important in the healthcare system is accuracy of the measured health data. But, the accuracy changes remarkably according to user's motion artifacts in real life. To elevate accuracy of health data, we proposed new algorithm to detect maximum point of pulse wave for heart rate extraction. and the proposed algorithm is to detect maximum points detect of pulse wave in photo-plethysmography signal included motion artifacts by fuzzy inference and multi sub-band filters. In results of experiment to evaluate the performance of the proposed algorithm, we could verify the proposed algorithm extracted maximum point of pulse wave in complex motion artifacts.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.129-132
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• 2008

손목에 착용하여 맥파와 산소포화도 등의 정보를 측정할 수 있는 유비쿼터스 광센서를 개발하였다. 유비쿼터스 광센서의 SNR의 향상을 위해 660nm의 LD와 904nm의 LD를 사용하였으며, 2종류의 LD는 각각 PD를 중심으로 $120^{\circ}$로 배치하였다. 또한 정확한 신호의 측정 및 분석을 위해 LabVIEW를 사용하였다. 제작된 광센서는 정확한 맥박 및 산소포화도의 측정이 가능하였으며 Beer-Lambert 곡선과 부합하여, 구성 및 설계가 정확함을 알 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.265-267
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• 2007

고혈압을 진단하고 치료함에 있어 정기적인 혈압의 측정 및 관리는 매우 중요하다. 본 논문에서는 요골 동맥혈에서 혈압 측정을 하기 위한 심전도 측정기와 광용적맥파 측정기를 설계하여 구성하였으며, 이를 이용한 맥파 전달 시간 측정을 LA(Left Arm), RA(Right Arm)에서 심전도와 요골동맥에서 광 용적맥파 신호를 측정하였다.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.99-106
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• 1998

Background: Bronchial asthma is a complex disease, which is characterized by spontaneous exacerbations of airway obstruction and persistent bronchial hyperresponsiveness. Animal models have fallen short of reproducing the human disease, particularly in mimicking the spontaneous and persistent airflow obstruction that characterized in asthma. In animals, airflow obstruction is usually assessed by measuring airflow resistance during tidal breathing under such invasive technique as tracheostomy and anesthesia. A noninvasive technique for measuring pulmonary function in small animals is needed to evaluate long-term changes in lung function during the course of experimentally produced disease without sacrificing the animal. Purpose: The purpose of this study was to evaluate early bronchoconstrcition after allergen challenge and airway responsiveness (AR) to inhaled methacholine in nonanethetized, unrestrained guinea pigs. Method: Guinea pig model of asthma was sensitized by subcutaneous injection with ovalbumin and challenged by inhalation of aerosolized ovalbumin(1% wt/vol ovlabumin). Airflow obstruction of conscious guinea pig was measured as specific airway resistance (airway resistance $\times$ thoracic gas volume). Airway resistance and thoracic gas volume of conscious guinea pig were assessed by body plethysmography before challenge and at regular intervals for as long as 30 minutes after challenge. AR to aerosolized methacholine of asthma group was compared with that of control group in body plethysmography. Result: Asthma model<> developed in 13 (65%) among 20 guinea pigs, in which early responses occurred in the airways after the exposure to inhalation with ovalbumin. Airway challenge with ovalbumin caused increase in specific airway resistance, which peaked at 6 minutes and amounted to a $231.5{\pm}30.4%$ increase from baseline. AR to aerosolized methacholine of asthma model increased significantly compared with control group. Conclusion: These results have showed a useful animal model to evaluate early bronchoconstrcition after allergen challenge and airway responsiveness in nonanethetized, unrestrained guinea pigs.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.05
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• pp.71-73
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• 1991

In this study electrical impedance plethysmograph was developed and each ten digital blood flow was measured for eight normal males and a patint with digital arterial reconstruction surgery. Blood flow of the digit with surgery was approximately fourty percent compared to that of the other normal digit. For the normal subjects, right-handed subjects generally have larger blood flow in right fingers than that in left fingers while it was reverse for the left-handed subjects. The relative average magnitude of the digital blood flow is the third, first, second, fourth, and fifth digit in descending order for the left and right hand, respectively. Blood flow of the fifth digit for all subjects except one was the smallest among the five digits.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.278-279
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• 2016

최근 웨어러블 장치의 개발로 인하여 다양하게 생체 신호를 측정하는 방법이 많아지고 있다. 이와 관련하여 대표적으로 측정하는 신호가 PPG(plethysmography) 신호이다. PPG 신호를 이용하여 맥박수, 혈박출량, SPo2 등의 값들을 추정할 수 있다. 그러나 웨어러블 장치의 특성상 동적잡음이 많이 발생하게 된다. 동적잡음을 제거하기 위한 방법들은 가속도 센서를 사용하는 방법, 칼만필터(Kalman filter)를 이용하는 방법 등 다양한 방법들이 존재한다. 그러나 여전히 범용으로 사용하기에는 한계가 있다. 본 논문은 Neural Network를 사용하여 개인별로 PPG 신호를 학습하여 PPG 신호의 이상 유무를 판단하고 이전 신호의 평균 맥박수를 사용하여 효과적으로 PPG 신호의 정확한 맥박수를 검출하는 알고리듬을 제안한다.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.1
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• pp.3-12
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• 2003

Ultrasonic pulsed Doppler velocimetry has become a standard international method of classifying carotid disease. Because the measured angle adjusted velocity increases as the Doppler angle increases, examinations should be performed at a convenient standard Doppler examination angle. An angle of 60 degrees is achievable throughout most examinations. Multiple Doppler viewing angles allow the acquisition of velocity vectors during the cardiac cycle, revealing the complex velocity patterns. Ultrasonic velocimetry (whether Doppler or time domain) is based on changes in the phase of the ultrasound echo. Other examinations can be done based on the echo phase. Slow motions of organs such as the brain can be used to monitor changes in edema. Measurements of tissue strain due to the pulsatile filling of the arterioles. This plethysmographic imaging method can display differences in tissue perfusion because of different tissue types and changes in autonomic activity.

• Speech Sciences
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• v.12 no.4
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• pp.77-92
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• 2005

Voice is made by systemic interaction of respiration, vocalization, articulation and resonation. There is no existing multi-channel voice analysis system to assess voice and respiration simultaneously. The most existing systems consist of. vocal fold vibration measurement such as stroboscopy, EGG (electroglottography) or laryngeal electromyography and voice analysis system. Since respiration has close relationship with voice simultaneous analysis of both vocal cord vibration and respiration are essential. In this study, a four channel integrated system are developed for acoustic analysis through microphone, vocal fold vibratory analysis using EGG, and respiratory analysis using two channel RIP (respiratory inductive plethysmography).

• Annual Conference of KIPS
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• 2015.04a
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• pp.1051-1053
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• 2015

다양한 종류의 생체 신호들을 모니터링하는 연구들이 활발히 진행되면서 이제는 병원이나 전문기관뿐만 아니라 일상 생활 속 에서 사람들이 스마트폰을 이용하여 특별한 제약 없이 편리하게 측정 가능하다. 이러한 스마트폰의 특성을 살리고 그 중 카메라 PPG (Photo-plethysmography) 모듈을 통해 얻은 생체 신호 정보를 분석하여 사용자에게 분석된 정보를 보여줄 수 있다. 또한 얻은 생체 신호로 심박수를 구하고 얻어진 심박수 정보를 활용하여 이를 사용자에게 Hologram으로 보여주는 것을 목표로 한다.