Treatment of Bone Repair by Inductively Magnetic Fields

안재목,이우철,김희찬,민병구 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.5

완전이식형 인공심장 구동을 위한 무선에너지 전송시스템의 개발

안재목,이우철,김희찬,민병구 대한전자공학회 1992 秋季綜合學術大會 論文集 Vol.14 No.2

In systems in which inductive coupling between a pancake-shaped coil on the surface of the body and a similar coil within the body is utilized for the transfort of electromagnetic energy, the minimization of temperature rise in the tissue is intimately related to the achievement of minimum losses in the region of the implanted coil. the new class of amplifiers, named "class E", for inverter is defined and is illustrated by a detailed description and a set of design equations for one single member of the class. For TET circuit the authors measured 65 to 76 percent efficiency at 198khz at 30 to 50 w output from IRF250 MOSFET transistor.

Electrohydraulic Pump-Driven Closed-Loop Blood Pressure Regulatory System

안재목,Ahn, Jae-Mok The Korean Society of Medical and Biological Engin 2007 의공학회지 Vol.28 No.4

An electrohydraulic (EH) pump-driven closed-loop blood pressure regulatory system was developed based on flow-mediated vascular occlusion using the vascular occlusive cuff technique. It is very useful for investigating blood pressure-dependant physiological variability, in particular, that could identify the principal mediators of renal autoregulation, such as tubuloglomerular feedback (TGF) and myogenic (MYO), during blood pressure regulation. To address this issue, renal perfusion pressure (RPP) should be well regulated under various experimental conditions. In this paper, we designed a new EH pump-driven RPP regulatory system capable of implementing precise and rapid RPP regulation. A closed-loop servo-controlwas developed with an optimal proportional plus integral (PI) compensation using the dynamic feedback RPP signal from animals. An in vivo performance was evaluated in terms of flow-mediated RPP occlusion, maintenance, and release responses. Step change to 80 mmHg reference from normal RPP revealed steady state error of ${\pm}3%$ during the RPP regulatory period after PI action. We obtained rapid RPP release time of approximately 300 ms. It is concluded that the proposed EH RPP regulatory system could be utilized in in vivo performance to study various pressure-flow relationships in diverse fields of physiology, and in particular, in renal autoregulation mechanisms.

혈중 목표 농도 자동 조절기(TCI) 개발 PART1 : 약동학적 모델의 수립과 검증

안재목,길호영 대한의용생체공학회 2002 의공학회지 Vol.23 No.5

본 논문에서는 혈중 목표 농도 자동 조절기(Target-controlled infusion system. TCI)를 개발하는 것으로써, 마취의가 혈중 목표 농도를 설정하면 사용약제의 약동학적 모델링에 의해서 주입속도를 자동적으로 계산하여 마취의 깊이를 예측하는 약동학적 모델의 수립과 검증 방법을 설명한다. 정확한 약동학적 모델의 구축은 시스템의 성능에 큰 영향을 미치므로 먼저 PART 1에서는 약동학적 모델을 구축하되 3-콤파트먼트 모델과 4-콤파트먼트 모델로 해석하였다. 기존의 TCI에서 사용하고 있는 3-콤파트먼트 모델에 가상의 효과처 구획(Effect Site Compartment)을 만들고 이를 네 버내 구획으로 가정한 4-콤파트먼트 모델(Four-Compartment Model)을 수립하였고, matlab 5.0을 이용하여 비교 분석하였다. 모델은 혈중 목표 농도 주입(Plasma Targeting)과 효과처 목표 농도 주입(Effect Site Targeting), 혈중 농도 유지를 위한 주입율 계산과 기타 마취 상태를 추정하는 정보를 포함한다. 시뮬레이션의 결과를 바탕으로 4-콤파트먼트 모델을 디지털 z-변환을 거쳐 디지털시그널프로세서에 프로그램하고 TCI시스템의 적용가능성을 평가하였다. 정맥 마취용 TCI는 오동작에 대한 검증이 반드시 요구되므로 구축한 모델링에 대한 시뮬레이션의 평가 방법을 설정하였다. 기존의 TCI시스템과는 달리 약동학적 약물 전달 속도 상수(k-파라미터)를 독립적으로 조절할 수 있는 기능이 추가되어 다양한 약제의 사용이 가능할 뿐만 아니라 새로운 약동학적 모델의 개발과 평가에 기여하게 되고, 환자의 체형과 병명에 따른 약동학적 모델의 변화에 대응할 수 있게 하였다. The target controlled infusion(TCI) pump system is a logical approach to the development of improved administration techniques of an intravenous anaesthetic agent. The principle of TCI system is based on an understanding of the pharmacokinetic properties, three or four compartment model. The TCI system is optimal and flexible control of the plasma drug concentration. But the clinical goal is always to achieve a therapeutic drug effect, not a therapeutic concentration. So we developed the algorithm to target the concentration at the site of drug effect rather than the concentration in the plasma. If impulse drug is inputted into body, the decline of plasma concentration with time is shown, resulting in the expression of the differential equation. Therefore, we must reformulate our three-compartment model as four-compartment model with the effect compartment. And we tested plasma targeting and effect targeting algorithm by computer simulation using four-compartment model. So we developed the TCI capable of applying all intravenous drugs by adjusting individual pharmacokinetic parameters independently.

New Aging Index Using Signal Features of Both Photoplethysmograms and Acceleration Plethysmograms

안재목 대한의료정보학회 2017 Healthcare Informatics Research Vol.23 No.1

Objectives: Acceleration plethysmograms (APGs) are obtained by taking the second derivative of photoplethysmograms (PPGs) and are noninvasive circulatory signals related to risk factors for atherosclerosis with age. There has been growing interest in the development of mobile devices to collect and analyze PPG single features for ambulatory health monitoring. The present study aimed to extract a new feature from the morphologies of APG and PPG signals to classify the dominant indices related to the pulsatile volume of blood in tissue according to age. Methods: Ten APG and 14 PPG indices were simultaneously extracted. All indices were compared via Pearson correlation coefficients (r) and a regression analysis. We introduced a combined index extracted from both the PPG and APG indices defined as the inflection point area plus the d_peak (IPAD). The participants included 93 healthy adults aged 36–86 years with a mean ± standard deviation age of 57.43 ± 11.99 years. Results: The d_peak and age index for the APG indices were significantly correlated with age (r = –0.408, p < 0.0001 and r = 0.296, p = 0.0039, respectively). Only the A1 time for PPG indices was moderately correlated with age (r = –0.247, p = 0.017). The stiffness index, including individual height information, was not related to age (r = –0.031, p = 0.7713). However, the combined IPAD index was significantly more correlated with age (r = 0.56, p < 0.001) than the other indices. Conclusions: The proposed index outperformed the other 24 indices for evaluating vascular aging. We suggest that the IPAD is a significant factor related to the clinical information embedded in the PPG waveform.

Wave Detection in Acceleration Plethysmogram

안재목 대한의료정보학회 2015 Healthcare Informatics Research Vol.21 No.2

Objectives: Acceleration plethysmogram (APG) obtained from the second derivative of photoplethysmography (PPG) is used to predict risk factors for atherosclerosis with age. This technique is promising for early screening of atherosclerotic pathologies. However, extraction of the wave indices of APG signals measured from the fingertip is challenging. In this paper, the development of a wave detection algorithm including a preamplifier based on a microcontroller that can detect the a, b, c, and d wave indices is proposed. Methods: The 4th order derivative of a PPG under real measurements of an APG waveform was introduced to clearly separate the components of the waveform, and to improve the rate of successful wave detection. A preamplifier with a Sallen-Key low pass filter and a wave detection algorithm with programmable gain control, mathematical differentials, and a digital IIR notch filter were designed. Results: The frequency response of the digital IIR filter was evaluated, and a pulse train consisting of a specific area in which the wave indices existed was generated. The programmable gain control maintained a constant APG amplitude at the output for varying PPG amplitudes. For 164 subjects, the mean values and standard deviation of the a wave index corresponding to the magnitude of the APG signal were 1,106.45 and ±47.75, respectively. Conclusions: We conclude that the proposed algorithm and preamplifier designed to extract the wave indices of an APG in real-time are useful for evaluating vascular aging in the cardiovascular system in a simple healthcare device.

의료용 무선 에너지 전달 장치의 개발

안재목,이동준 대한의용생체공학회 1995 의공학회지 Vol.16 No.4

완전 이식형 인공심장 개발의 일환으로 무선에너지 전송장치를 개발하였다. 본 연구에서는 피하에 이식된 2차 코일과 피부표면에 놓인 1차 코일 간의 자기 유도의 원리에 의한 전기에너지 전송시스템을 개발하였으며, 이식될 소자의 소형화 및 전송효율의 향상을 목표로 하였다. 클래스 E 공진 증폭기를 이용하여 인공심자의 구동에 요구되는 40 Watt 전송시 75% 이상의 전송 효율을 얻었다. 또한 동물 실험을 실시하여, 체내 성능을 검증하였고 체내 이식부의 생체 적합성도 확인하였다. As a part of electro-mechanical totally implantable artificial heart (TIAH) program, a transcut- aneous energy transmission system has been developed. By mutual magnetic induction between the first coil on the skin and the subcutaneously implanted second coil, the system transfers elctrical power through the skin. This research aimed at minimizing the size of the implanted part as well as maximizing the transfer efficiency. Using class I amplifier, we achieved above 75% power transfer efficiency at average 40W power transfer level which is required for normal TIAH operation. In vivo performance of the developed system and bio-compatibility of the material used in Implanted parts were evaluated through animal experiments.

혈중 목표 농도 자동 조절기(TCI) 개발 PART2: 시스템 구현 및 평가

안재목 대한의용생체공학회 2003 의공학회지 Vol.24 No.1

Based on the 4-compartmental pharmacokinetic model developed in PART1, target-controlled infusion(TCI) pump system was designed and evaluated. The TCI system consists of digital board including microcontroller and digital signal process(DSP), analog board, motor-driven actuator, user friendly interface, power management and controller. It provides two modes according to the drugs: plasma target concentration and effect target concentration. Anaesthetist controls the depth of anaesthesia for patients by adjusting the required concentration to maintain both plasma and effect site in drug concentration. The data estimated in DSP include infusion rate, initial load dose, and rotation number of motor encoder. During TCI operation, plasma concentration. effect site concentration, awaken concentration, context-sensitive decrement time and system error information are displayed in real time. Li-ion battery guarantees above 2 hours without power line failure. For high reliability of the system, two microprocessors were used to perform independent functions for both pharmacokinetic algorithm and motor control strategy.

인공심장용 무선 에너지 전송 시스템의 개발 ( Development of Transcutaneous Energy Transmission System for Implantable Total Artificial Heart )

이우철,안재목,이상훈,민병구 대한전자공학회 1991 대한전자공학회 학술대회 Vol.1991 No.01

Artificial Heart Control

엄경식,안재목,조영호,박용남,조한상,김욱은,김원곤,노준량,원태희,김희찬,민병구,Eom, Gyeong-Sik,An, Jae-Mok,Jo, Yeong-Ho,Park, Yong-Nam,Jo, Han-Sang,Kim, Uk-Eun,Kim, Won-Gon,No, Jun-Ryang,Won, Tae-Hui,Kim, Hui-Chan,Min, Byeong-Gu The Korean Society of Medical and Biological Engin 1999 의공학회지 Vol.20 No.6

심장은 생명의 가장 중요한 장기 중 하나이며, 이 중요성은 인공심장의 연구를 불러일으켰다. 본 고에서는 전세계적으로 연구되는 인공 심장 제어의 방법론, 추세 그리고 현 상황을 비교 분석하였다. 인공 심장 개발에 있어서 중요한 연구 분야 중 하나인 인공 심장 제어는 자연 심장의 역할을 최대한 모방하여야 하는데 현실적으로 각종 생리적 제어 인자를 얻기에는 센서 기술의 한계가 있다. 따라서 인공 심장을 위한 많은 제어 변수가 연구되었으나, 단지 몇 가지만 실제로 적용되는 상태이다. 본고에서는 왜 다른 요인들이 제외되었으며 무엇이 현재 제어 방식의 선택 기준으로 고려되었는지를 설명한다. 이것을 설명하기 위하여 인공 심장의 제어에 앞서서 자연 심장의 제어를 짧게 설명하고, 5개의 대표적인 인공 심장 제어 연구 조직을 선정하여 소개와 정리를 하였다.