• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.428-435
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• 2000

Negative ion generation in an inductively coupled oxygen plasma was investigated by using a Langmuir probe. It was observed that the probe current ratio of the positive ion saturation current and the negative current which is consisted of the electron current and the negative ion current, and also the potential difference between the floating potential and plasma potential vary with the RF input power and more sensitively with the operating pressure, respectively. Results show that the operating condition to achieve the maximum probe current ratio and the minimum potential difference shift from the low pressure region to the high pressure regions with increasing the input power. It implies that the generation of the negative oxygen ions increases and the recombination of the positive and negative ions are enhanced in the plasma.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.309-310
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• 2022

코로나19 팬데믹을 계기로 원격의료의 수요가 폭발하여 비대면 진료가 가능하도록 법률을 개정하려는 추세에 필요한 서비스로 시간과 비용이 없고, 거리 두기 단계 상향등으로 병원에 방문하지 못하는 환자가 늘어나고 있다. 하지만 시중에 건강상태를 확인할수 있는 장비를 판매하지만 전문적인 지식이 없는 일반인은 정확하게 결과를 알 수 없고 한가지의 검사만 측정이 가능하기 때문에 검사결과를 확인하고 싶으면 병원을 방문해야한다. 본 논문은 전문적인 지식이 없는 일반인도 자신의 건강상태를 확인가능하게 하기 위해 심박, 심전도, 산소포화도, 체온센서의 측정값을 그래프로 표현한 후 검사결과를 토대로 의사와 원격진료가 가능하여 병원을 방문하지 않고 의사와 상담 및 진료가 가능하다. 병원에 입원이 불가능한 환자일 경우 산소포화도 측정값이 95%미만이면 산소공급 즉 응급처치가 가능하다.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.159-163
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• 1995

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.813-820
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• 2009

This paper describes the realization of ubiquitous healthcare monitoring system using wearable pulse oximeter based on a wireless sensor network. In order to obtain information of oxygen saturation from a patient, a small size and low power consumption wearable pulse oximeter was designed. Information of oxygen saturation collected by wireless sensor node was transmitted wirelessly to a base-station for storage and display purposes via wireless sensor network. Wireless sensor nodes were programmed by TinyOS application to perform data acquisition and transmission. Lab VIEW server program was designed to monitor information of oxygen saturation and process the measured PPG (photo plethysmogram) signals to APG(Accelerated plethysmogram) signals by appling second order derivatives. PPG signals are simple and cost effective technique to measure blood volume change.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.860-863
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• 2003

Pulse oximetry has gained wide spread clinical acceptance in the latter part of the 21st century. The principle of pulse oximetry is based on the red and infrared light absorption features and uses a light emitter with red and infrared LEDs that shines through a reasonably translucent site with good blood flow. There are two methods of sending light through the measuring site : transmission and reflectance. After the transmitted red and infrared signals pass through the measuring site and received at the photodetector, the red/infrared ratio is calculated. But, pulse of oximeters are so sensitive that they may detect pulses when pressure is too low to provide adequate tissue blood flow, that is, SpO2 may decrease due to O2 consumption by the finger of the pulsing but stagnant arterial blood at low pressure or with vasoconstriction. This project has the limitations of pulse oximetry. Therefore, this paper is focused on the resuction of motion artifact that caused by moving when someone measures with SpO2 system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.293-297
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• 2009

This paper describes a real-time reliable measurement and analysis system for ubiquitous healthcare based on IEEE802.15.4 standard. In order to obtain and monitor physiological body signals continuously, wearable pulse oximeter is designed in wrist that could used to measure oxygen saturation of a patient unobtrusively. The measured data was transferred to a central PC or server by using wireless sensor nodes via a wireless sensor network for storage and analysis purposes. LabVIEW server program was designed to monitor and process the measured photoplethysmogram(PPG) to accelerated plethysmogram(APG) by appling second order derivatives in server PC. These experimental results demonstrate that APG can precisely describe the features of an individual's PPG and be used as estimation of vascular elasticity for blood circulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.678-681
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• 2003

In this paper, we aims to develop a microcontroll er-based portable pulse oximeter using Compact Flash Interface. First, portable pulse oxineter system is designed to record 2 channel of biosignals simultaneously, including 1 channel of SpO$_2$ and 1 channel of pulse rate. It is very small and portable. Besides, the system makes it possible to measure a patients condition without an additional medical equipment. We tried to solve the problems generated by a patient's motion. That is, we added an analog circuit to a traditional pulse oximeter in order to eliminate the change of the base line. And we used 2D sector algorithm. As present, SpO$_2$ modules are completed. But there are still many further development needed in order to enhance the function. Especially, compact flash interface remains the most to complete. Second, ECG monitoring system uses almost same as present 3-lead ECG system. But we focus on the analog part, especially in filter. The proposed filter is composed of two parts. One is a filter to remove the power-line interface. The other is a filter to remove the baseline drift. A filter to remove the power-line and the baseline drift is necessarily used in the ECG system. The implemented filter have three features; minimizing the distortion in DC component, removing the harmonic component of power-line frequency. Using compact flash interface, we can easily transfer a patient's personal information and the measured signal data to a network based server environment. That means, it is possible to implement a patient's monitoring system with low cost.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.2
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• pp.169-175
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• 2006

Purpose: Esophagogastroduodenoscopy (EGD) is a very useful procedure in diagnosing gastrointestinal diseases. However, there can be some difficulty in performing this procedure in children due to the associated discomfort. Recently, sedative agents such as midazolam have been introduced to alleviate this problem quite successfully. In our study, we attempted to confirm the safety and efficacy of midazolam use by monitoring the vital signs of children undergoing endoscopy. Methods: We analyzed data on 244 children who received EGD in the department of pediatrics at Severance Hospital, Yonsei University between August 2003 and July 2005. We evaluated $O_2$ saturation, heart rate and change of mental status before and during the procedure and analyzed the results using the SPSS 12.0 package (Chi-square test, cross table method, etc.). Results: There was no significant difference in vital signs measured before and during EGD between midazolam treated and non treated children. There was no significant relationship between the amount of midazolam given and $O_2$ saturation or a change of mental status. Regarding the $O_2$ saturation, it was decreased during EGD in both groups with p<0.01 though no difference was noted between the groups; the $O_2$ level was maintained above 95% in all patients. The heart rate was also increased during EGD in both groups with a p<0.01; however, no significant difference was noted between the groups. Conclusion: We confirmed the safety of low dose midazolam by evaluating the vital signs of children during endoscopies. However, the doses used were not sufficient for sedation or to obtain an amnestic effect.

• Science of Emotion and Sensibility
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• v.22 no.1
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• pp.89-100
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• 2019

Sleep apnea, a medical condition associated with a variety of complications, is generally monitored by standard sleep polysomnography, which is expensive and uncomfortable. To overcome these limitations, this study proposes an unconstrained wearable monitoring system with stretch-fiber sensors that integrate with the wearer's clothing. The system allows patients to undergo examinations in a familiar environment while minimizing the occurrence of skin allergies caused by adhesive tools. As smart clothing for adult males with sleep apnea, long-sleeved T-shirts embedding fibrous sensors were developed, enabling real-time monitoring of the patients' breathing rate, oxygen saturation, and airflow as sleep apnea diagnostic indicators. The gauge factor was measured as 20.3 in sample 4. The maximum breathing intake, measured during three large breaths, was 2048 ml. the oxygen saturation was measured before and during breath-holding. The oxygen saturation change was 69.45%, showing a minimum measurable oxygen saturation of 70%. After washing the garment, the gauge factor reduced only to 18.0, confirming the durability of the proposed system. The wearable sleep apnea monitoring smart clothes are readily available in the home and can measure three indicators of sleep apnea: respiration rate, breathing flow and oxygen saturation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.549-552
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• 2009

본 논문에서는 심폐기능에 이상이 있는 중환자의 지속적인 감시와 진단을 위한 방법으로 Swan-Ganz Catheter를 체내에 삽입하여 심박 출량과 혼합정맥혈 산소포화도를 기존 장비들보다 정밀하게 측정할 수 있는 모듈을 개발하고자 한다. Swan-Ganz Catheter에는 두 개의 온도센서와 한개의 압력센서를 포함하고 있으며 이를 통해 입력되는 센서 값을 세밀하게 수집하고 이를 기반으로 일회 심박 출량, 전신 및 폐혈관저항, 산소소모량 등을 계산하여 환자의 상태를 보다 정확하게 진단 및 치료가 가능하게 한다.