• 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.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.93-100
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• 1992

Sinterability, mechanical and electrical properties of yttria-stabilized zirconia(92 mole% $ZrO_{2}$+8 mole% $Y_{2}O_{3}$) doped with 0.5 mole% $SiO_{2}$ and $0{\sim}2.0 mole%{\;}Al_{2}O_{3}$ were studied as a function of $Al_{2}O_{3}$ addition. Sintered density increased with increasing $Al_{2}O_{3}$ addition up to 0.5 mole % but leveled off with further addition. Victors hardness is proportional to sintered density. The specimen with 0.5 mole% $Al_{2}O_{3}$ and 0.5 mole% $SiO_{2}$ exhibited the maximum electrical conductivity and revealed a maximum electromotive force for a given oxygen partial pressure. Experimental voltage curve of this oxygen sensor take on a sharper, more steplike transition at the stoichiometric A/F ratio than those of other commercial oxygen sensors.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.247-252
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• 1999

The oxygen electrode of a biosensor needs enzyme immobilized membrane and a dialysis membrane to measure the oxygen concentration that remains after an enzyme reacts with its substrate. Accodingly, a single-layer PVA laminated CTA/PCL membrane was developed as an oxygen biosensor electrode. The enzymes were immobilized on a cellulose triacetate/polycarprolactone membrane using the 1,1'-carbonyl diimidazole(CDI) method, and then laminated with polyvinyl alcohol, aldehyde and acid. The alcohol oxidase and PVA laminated CTA/PCL membrane was tested with various concentration of enzyme substrates using a Yellow Springs Instrument(YSI) oxygen sensor. Under 5-10mmol substrates produced $0.37{\sim}0.83{\mu}A$(r=0.995) currents, and ater 8 weeks the glucose oxidase activity remained at about 56%, while the other activities remained very low. A SEM indicated a smooth surface and tightly attached PVA on the enzyme-immobilized CTA/PCL membranes.

• Analytical Science and Technology
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• v.20 no.1
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• pp.1-9
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• 2007

The BOD (biochemical oxygen demand) sensor was fabricated by covering a dissolved oxygen (DO) probe with a microbe-impregnated membrane and a dialysis membrane. Various microorganisms isolated from the soils, water and activated sludge have been evaluated for measuring biochemical oxygen demand (BOD); Bacillus species HN24 and HN93 were selected as they exhibited rapid oxygen consumption and fast recovery. Improved BOD sensor could be prepared by using mixed microbes (Bacillus subtilis, Bacillus sp. HN24 and Bacillus sp. NH93) and silicon rubber gas-permeable membrane for DO probe, and by bubbling 50% $O_2$ ($N_2$ valence) through background buffer solution. This system exhibited excellent analytical performance resulting in good linearity ($r^2=0.9986$) from 0 to 100 mg/L level of BOD.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.569-574
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• 2014

We developed and evaluated a fluorescence-based optical DO sensor (OS-100, Global Optical Communication Ltd., Korea) for long-term monitoring of the dissolved oxygen concentration in waste water treatment. Fluorescent sensing membrane containing $Ru(Dpp)_3{^{2+}}$ (tris(4,7diphenyl-1, 10-phenanthroline) ruthenium(II)) was prepared with GA sol-gel matrix and coated on a quartz plate by sprayed method. Properties of sensor film exhibit deviation about ${\pm}1%$ under wide range of DO concentration from 3 to 10. The developed optical DO sensor was actually mounted in waste water from dyeing industry and successfully applied for on-line DO monitoring. Online monitoring results showed the changes of DO concentrations in wastewater treatment processes with accuracy better than ${\pm}2%$ during the 6 months measurements period in vicious environmental conditions.

• Journal of the KSME
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• v.33 no.6
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• pp.515-522
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• 1993

센서는 자연현상을 감지하는 소자로 계측 및 제어시스템의 구성요소로 이용되며, 센서를 이용 하여 Closed-loop System의 구성을 가능케 하며, 지능화된 시스템을 구현 할 수 있다. 센서는 압력, 유량, 온도, 자장, 광 등을 측정하는 물리적 센서, pH, 이온, 산소 등의 구성물을 감지하는 화학센서, 인체의 혈당량, 뇌의 상태, 냄새 등을 측정하는 바이오 센서로 대별될 수 있다. 이중 물리적 센서는 기계적 시스템에 많이 이용되며, 특히 압력, 유량센서는 자동차에 있어서 엔진의 Manifold, 엔진오일, 브레이크 오일, 타이어, 연료 등의 상태를 측정하는데 사용되고 있다. 예를 들어 1980년대에는 미국 Ford와 Motorola사가 공동으로 반도체공정 기술을 이용한 용량 형(capacitive) 압력센서를 개발하여 엔진의 컨트롤시스템에 이용하였다. 이러한 압력센서는 1988년에 15억불의 매출을 기록하였으며, 1955년에는 30억불로 늘어날 전망으로 있어 가장 많이 사용되는 센서로 각광을 받고 있다. 이글에서 압력센서의 원리 및 종류에 대하여 알아보고, 마 이크로머시닝 기술 등의 제작방법과 이의 응용에 대하여 논의하려 한다.

• KSBB Journal
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• v.21 no.4
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• pp.241-247
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• 2006

The present study was intended to examine a basic scheme to determine the biochemical oxygen demand(BOD) of livestock wastewater by means of six individual dissolved oxygen(DO) sensors and its multi-measurable meter. Maximal point of the first order time derivative of the DO difference between DO distribution of sterilized livestock wastewater and that of non-sterilized livestock wastewater, was considered as the oxygen uptake rate(OUR) of microorganisms in livestock wastewater, as determined to be 0.00074 mg $O_2/{\ell}{\cdot}sec$. The present study showed that there was a fair linear relationship(97.72%) between maximal OUR and BOD values of livestock wastewater, the latter being determined by classical Winkler azide method. It was thus concluded that the present multi-biosensor system might be applicable to an on-line system for measurement of BOD of livestock wastewater.

• Electrical & Electronic Materials
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• v.8 no.6
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• pp.816-822
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• 1995

본 고에서는 지구환경문제에 관련된 가스와 그들의 검지를 위한 가스센서에 관하여 살펴보고자 한다. 환경오염을 방지하려는 노력과 대책이 전세계적으로 추진되고 있는 시점에서 특히 대기오염의 주범인 환경가스에 대한 고성능 센서의 개발은 필수불가결하다. 그러나 현재에 사용되고 있는 환경가스센서는 차량의 배기계통에 사용되는 산소센서나 연소배출가스를 검지하는 소수의 가스센서외에는 아직 실용화되지 못하고 있다. 따라서 고온, 부식등의 과혹한 조건하에서 안정하고, 고성능의 센서의 개발은 물론 센서를 구동시키는데 필연적인 신호처리 등 주변기술 또한 병행해서 발달되어야 할 것이다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.5
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• pp.187-191
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• 2019

Perovskite-type oxides have consistently attracted considerable attention for their applications in high-temperature electrochemical devices, such as electrolytes and electrodes of solid oxide fuel cells, oxygen permeating membranes and sensors etc. Among them, the electrical conductivity of 10 % Sr and 10 % Mg doped $LaAlO_3$ (LSAM9191) was measured using impedance spectroscopy and 4-probe d.c. method. Below $550^{\circ}C$, the grain boundary resistance mostly determined the overall conductivity; however, it nearly disappeared above $800^{\circ}C$. Using the defect model and curve fitting, the ionic and electronic conductivity contributions were also separated. In the temperature region where the sample resistance is mostly determined by the grain volume property, LSAM9191 was an oxygen ion conductor at low $Po_2$ and a mixed conductor at high $Po_2$. With increasing temperature, the ionic conduction region only slightly increased. Thus, LSAM9191 is a promising material as an oxygen ion conductor at high temperature and in low $Po_2$.

• 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.