• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.101-106
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• 1995

In this paper, the patient monitor consisting of ECG/Respiration Amplification, Front end CPU, Main CPU, Main Controller, Video Amplifier, Display Controller, Waveform Generator, Bus & Power Supply, 8097 Processor was developed. This patient monitor measures the patient's states in the hospital such as elecctro-cardiography, respiration, blood pressurae and temperature. The control and processing methods based on micro-processor employ the flexibility, extensibility over other conventional system. The followings are incorporated in this system. First, ECG/RESP measures the respiration by impedence pneumography. Second, FECPU utilizes an Intel 8031 microcontroller. Third, Controller function originate from a LSI CRT controller.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.309-316
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• 1989

In this paper, the patient monitor consisting of amplifier, scan converter, A/D converter, CRT amplifier, and micro-controller part was developed. This patient monitor measures the patient's 4 states in the hospital such as electro-cardiography, respiration, blood pressure, and temperature. The control and processing methods based on micro-processor employ the flexibility, extensibility and economy over other conventional system. The followings are incorporated in this system. First, record the heart rate trends for 1 and 4 hours respectively. Second, measures the respiration by impedance pneumography. Third, measures the blood pressure with auto-zero balance. Fourth, linesrize the temperatures by bridge method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.503-506
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• 2001

There are four factors for patient monitoring : electrocardiography, blood pressure, temperature and respiration. While there are a lot of studies of E.C.C (electro-cardiography) monitoring system in the world, the studies of Respiratory system are not enough and leave much to be desired in the country. In this paper, we developed a respiratory system with the electrical impedance change of the lungs depending on the breath. Using the same electrode, we can monitor E.C.C and Respiration simultaneously, so we can monitor a patient's no-breathing state due to the central nerve paralysis in the emergency room easily. In this monitoring system, the analog part was made separated from the digital part for reducing power source noise and protecting patient from electric shock. The analog part consists of the several parts a high-frequency sine-wave generator, all amplifier for amplifying any impedance change signal, an analog processing part for rectifying and filtering. And the digital parts consists of three parts an AD convertor for converting analog signal to digital signal, digital filter, and a digital part for digital signal processing. This system's merits are using the same electrode with E.C.C and developing the multiple patient monitoring system easily.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1303-1310
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• 2016

In this paper, electrocardiogram (ECG) analog front end with supply voltage of 0.5V has been designed and verified by measurements of fabricated chip. ECG is composed of instrument amplifier, 6th order gm-C low pass filter and variable gain amplifier. The instrument amplifier is designed to have gain of 34.8dB and the 6th order gm-C low pass filter is designed to obtain the cutoff frequency of 400Hz. The operational transconductance amplifier of the low pass filter utilizes body-driven differential input stage for low voltage operation. The variable gain amplifier is designed to have gain of 6.1~26.4dB. The electrocardiogram analog front end are fabricated in TSMC $0.18{\mu}m$ CMOS process with chip size of $858{\mu}m{\times}580{\mu}m$. Measurements of the fabricated chip is done not to saturate the gain of ECG by changing the external resistor and measured gain of 28.7dB and cutoff frequency of 0.5 - 630Hz are obtained using the supply voltage of 0.5V.

• Journal of Chest Surgery
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• v.28 no.5
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• pp.437-442
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• 1995

We developed an experimental model of brain death using dogs. Brain death was caused by increasing the intracranial pressure[ICP suddenly by injecting saline to an epidural Foley catheter in five female mongrel dogs[weight, 20-25Kg .Hemodynamic and electrocardiographic changes were evaluated continuously during the process of brain death. 1. Abrupt rise of ICP after each injection of saline followed by a rapid decline to a new steady-state level within 15 minutes and the average volume required to induce brain death was 7.6$\pm$0.8ml.2. Body temperature, heart rate, mean pulmonary arterial pressure, left ventricular[LV enddiastolic pressure and cardiac output was not changed significantly during the process of brain death, but there was an increasing tendency.3. Mean arterial pressure and LV maximum +dP/dt increased significantly at the time of brain death.4. Hemodynamic collapse was developed within 140 minutes after brain death.5. Marked sinus bradycardia followed by junctional rhythm was seen in two dogs and frequent VPB`s with ventricular tachycardia was observed in one dog at the time of brain death. Hyperdynamic state develops and arrhythmia appears frequently at the time of brain death. Studies on the effects of brain death on myocardium and its pathophysiologic mechanism should be followed in the near future.

• Journal of Biomedical Engineering Research
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• v.28 no.1
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• pp.132-138
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• 2007

MR(magnetic resonance) image of moving organ such as heart shows serious distortion of MR image due to motion itself. To eliminate motion artifacts, MRI(magnetic resonance imaging) scan sequences requires a trigger pulse like ECG(electro-cardiography) R-wave. ECG-gating using cardiac cycle synchronizes the MRI sequence acquisition to the R-wave in order to eliminate image motion artifacts. In this paper, we designed ECG/PPG(photo-plethysmography) gating system which is for eliminating motion artifacts due to moving organ. This system uses nonmagnetic carbon electrodes, lead wire and shield case for minimizing RF(radio-frequency) pulse and gradient effect. Also, we developed a ECG circuit for preventing saturation by magnetic field and a finger plethysmography sensor using optic fiber. And then, gating pulse is generated by adaptive filtering based on NLMS(normalized least mean square) algorithm. To evaluate the developed system, we measured and compared MR imaging of heart and neck with and without ECG/PPG gating system. As a result, we could get a clean image to be used in clinically. In conclusion, the designed ECG/PPG gating system could be useful method when we get MR imaging of moving organ like a heart.

• Journal of Chest Surgery
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• v.36 no.5
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• pp.329-334
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• 2003

Backgound: Cryoablation and radiofrequency ablation have been used to treat the atrial fibrillation. Some reports insisted that the microwave ablation Is a better method for a deep and extensive lesion. Material and Method: From December 2001 to July 2002, we peformed 8 microwave ablations in patients who needed mitral valve surgery (7 MVR, 1 MVR+AVR). There were 3 men and 5 women, and their mean age was 43.4$\pm$8.3 years and mean follow up period was 5.6$\pm$2.4 months respectively. The microwave was applied on endocardium or epicardium by Lynx (Afx, inc.) using a power of 45 watts for 25 seconds. We studied the left atrial dimension, the left atrial function and the sinus conversion with echocardiography and electro-cardiography at three times; 1) before the operation, 2) immediately after the operation, and 3) 6 months after the operation. Result: There was no complication and no mortality. The mean aortic clamping time was 104.6$\pm$25.0 minutes, and the mean total bypass time was 130.5$\pm$28.7 minutes. The rate of sinus conversion was 75%, A wave across the mitral valve was a mean of 77.0$\pm$24.8 cm/sec, and the AVE was a mean of 0.46$\pm$0.17 at 5.6 months postoperatively Conclusion: There was no difference in the early result of microwave ablation compared to other methods. The microwave ablation was an acceptable method due to its convenient application especially in beating heart.