• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.153-162
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• 2000

Triple points of high purity materials have been used to calibrate primarily the capsule-type platinum resistance thermometer (PRT) in the temperature range of the triple point of equilibrium hydrogen (13.8033 K) and water (273.16 K). In this work, triple points of Ne, $O_2$, Ar, Hg and $H_2O$ except for the triple point of equilibrium hydrogen were realized to establish the International Temperature Scale of 1990 (ITS-90). At each fixed point, two capsule-type PRTs, which were selected for the international comparison, were tested two times. The combined uncertainties of the realization of each triple point were calculated considering the type A and type B evaluation. In Korea Research Institute of Standards and Science, the combined standard uncertainties of the defining triple Points by the ITS-90 were estimated to about 0.18 mK for Ne, 0.14 mK for $O_2$, 0.14 mK for Ar, 0.24 mK for Hg and 0.11 mK for $H_2O$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5847-5855
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• 2013

The purpose of this research is to develop Dementia-diagnosis application program through inter-working between biometric sensors and smart phone with diagnostic programs. Receiving data from 2 biometric sensors, SpO2 and HRV(heart rate variability) with Bluetooth and adding scores from questionnaires and memory test game, smart phone can draw a final Dementia Index(DI). Simple clinical tests provided threshold for Dementia, and diagnosis was made by comparing the DI with the threshold. We performed testing on persons aged over 60 and found out the proposed application can be used to diagnose Dementia easily and quickly. Additionally, we have shown the potential of oxygen chamber combined with Dementia-diagnosis application as a medical equipment to ease or cure Dementia in its early stages.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.395-400
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• 2017

The paper discussed the air-to-fuel ratio control of automotive fuel-injection systems using the cerebellar model articulation controller(CMAC) neural network. Because of the internal combustion engines and fuel-injection's dynamics is extremely nonlinear, it leads to the discontinuous of the fuel-injection and the traditional method of control based on table look up has the question of control accuracy low. The advantages about CMAC neural network are distributed storage information, parallel processing information, self-organizing and self-educated function. The unique structure of CMAC neural network and the processing method lets it have extensive application. In addition, by analyzing the output characteristics of oxygen sensor, calculating the rate of fuel-injection to maintain the air-to-fuel ratio. The CMAC may easily compensate for time delay. Experimental results proved that the way is more good than traditional for petrol control and the CMAC fuel-injection controller can keep ideal mixing ratio (A/F) for engine at any working conditions. The performance of power and economy is evidently improved.

• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.222-231
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• 2001

The material properties of $SnO_2$ were investigated as a function of the amount of $Fe_2O_3$, the partial pressure of oxygen, the concentration of CO gas, and temperature. $Fe_2O_3$-doped $SnO_2$ thick films were prepared by the screen printing technique on alumina substrate. The specimens sintered at $700^{\circ}C$ for 6 hours showed little difference of the grain size and narrow distribution with the content of $Fe_2O_3$. The electrical conductance of undoped $SnO_2$ is high at low firing temperature and at low partial pressure of oxygen. The electrical conductance of $Fe_2O_3-$-doped $SnO_2$ is increased with measurement temperature, but decreased with the content of $Fe_2O_3$. The dependence of oxygen partial pressure is decreased with dopant addition. The highest sensitivity and the good properties of response speed and repeatability for CO gas were observed on the specimen with 0.1 mol% $Fe_2O_3$ at $350^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.15 no.2
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• pp.97-101
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• 2006

Silver electrode having a high Electrocatalytic activity is oxygen-permeable electrode, in which oxygen ad-atoms are adsorbed and moved toward YSZ electrolyte by bulk diffusion. It is the different point in comparison to usual porous electrodes, especially platinum, which react with oxygen only in TPBs(Three Phase Boundaries). Also ad-atoms at TPBs of Pt are diffused to YSZ electrolyte by interfacial diffusion mechanism. These properties were used for turning down the operating temperature of YSZ from over $600^{\circ}C$ to below $450^{\circ}C$. The different heat-treatment temperature between a working electrode and a reference electrode suppresses the formation of silver oxides and reduces a volatility of Ag as well. Above all, these own characteristics and special processes of Ag improved a long-term stability of a oxygen sensor.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.273-280
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• 2008

Monolith aperture-type oxygen sensors with simple structure of YSZ(pin-hole)/Pt/ YSZ(solid electrolyte)/Pt were fabricated by co-firing technique. To enhance the yield of productivity, a couple of YSZ green sheets for diffused barrier and solid electrolyte were prepared by tape-casting and co-firing method. The limit current characteristics of the oxygen sensors were measured between 500 and $650^{\circ}C$ The heating temperature of $600^{\circ}C$ was optimum as a portable oxygen sensor in the range of oxygen concentration from 0 to 75 vol%. Linear proficiency of limit current behavior as a function of oxygen concentration was controlled by the variation of aperture dimension. The fabricated oxygen sensors showed the stable sensing output for 30 days. Gas leakage in bonding area due to warping, cracking and thermal cycling was not found in the period.

• Journal of Sensor Science and Technology
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• v.18 no.6
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• pp.441-448
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• 2009

Magnesia partially stabilized zirconia(Mg-PSZ) solid electrolytes for an improvement of thermal shock resistance, which is suitable for the measurement of oxygen activity in a molten steel, were prepared by post-thermal aging treatment. The steelmaking oxygen sensor elements were formed by an injection molding method, sintered at $1650^{\circ}C$, and then thermal aged ranged from 1250 to $1400^{\circ}C$. Sintered density and porosity were decreased as increasing the magnesia content in a zirconia-magnesia solid solution. Fractions of cubic phase to the synthesized Mg-PSZ solid electrolytes were ranged from 13.13 to 79.54.% after post-thermal aging treatment. Very dense microstructure without voids in the grains was obtained by the post-thermal aging process. Fine tetragonal phase crystallites precipitated on the cubic surface during post-thermal aging up to $1300^{\circ}C$ improve a thermal shock resistance and reappearance of electro motive force(EMF) curve.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1246-1249
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• 2008

우리 나라는 고령화 사회로 접어들었고 그에 이어 초 고령화 사회가 예상되는 가운데, 실버 세대를 위한 체계적이고 실질적인 의료 환경이 요구 되고 있다. 독거노인과 거동이 불편한 노인들을 위하여 USN을 활용한 노인 건강관리 시스템(U-SilverCare)의 필요성이 급증하고 있다. 본 논문은 가속도 센서(Accelerometer Sensor), 혈중 산소포화도 센서 (POximeter Sensor), 심장박동센서(EKG Sensor)를 이용하여 실생활에서 일어날 수 있는 상황을 4가지로 구성, 실버 세대를 위한 U-SilverCare 응급상황 통보 시스템 시나리오를 구현하였다.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.36-43
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• 2000

In oder to enhance the selectivity of TMA(trimethylamine) gas, the ZnO-based films which were doped with $Al_2O_3$, $TiO_2, $In_2O_3$ and $V_2O_5$ catalysts with various weight percents were deposited in oxygen by RF magnetron sputtering method. To improve electrical stability of sensors, the ZnO-based films were annealed in oxygen at $700^{\circ}C$ for 1 hour. The TMA selectivity of sensors was defined by the magnitude($S_{TMA}/S_{DMA}$ and $S_{TMA}/S_{NH3}$) of TMA sensitivity relative to DMA and sensitivity ammonia($NH_3$) sensitivity, respectively. The $ZnO+Al_2O_3(4\;wt.%)+TiO_2(1\;wt.%)+In_2O_3(1\;wt.%)$ sensor showed high $S_{TMA}/S_{DMA}$ of 5.9 and $S_{TMA}/S_{NH3}$ of 26 to 160 ppm at the working temperature of $300^{\circ}C$ respectively.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1660-1663
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• 1999

혈액 내의 요소 농도는 신장병 진단의 척도로서 정확한 측정이 필요하다. 요소의 농도는 전위차법을 이용하여 정확히 검출할 수 있으며 이를 위하여 효소를 고정화시킨 전극형 센서를 사용하였다. 전도성 고분자로서 P3MT(Poly(3-methylthiophene) )와 PPy(polypyrrole)를 효소 고정화에 이용하였다. PPy는 전기적 특성이 좋고 중합 및 효소의 고정화가 용이하며 중합 과정이 상대적으로 신속하고 비용도 저렴하다는 장점은 있으나. 다소 불안정하다. P3MT는 PPy와 마찬가지로 전극 상에 단량체가 전기적 산화에 의하여 중합되고 일반적으로 전해질 이온이 도우핑된 상태나 도우핑 되지 않은 상태 모두에서 산소. 습도. 온도에 대하여 매우 안정하다. 본 연구에서는 3-methylthiophene과 pyrrole을 전기 중합하여 urease를 고정화한 요소센서의 특성(감도, 안정성, 직선성)을 비교하였다. P3MT를 이용한 센서와 PPy를 이용한 센서 각각에 대해 감도는 P3MT가 32.3mV/decade, PPy가 4.7mV/decate로서 P3MT가 우수하였고 직선성도 보다 뛰어났으며 순환 전압 전류 곡선을 분석한 결과 P3MT가 PPy보다 안정성도 우수한 특성을 보였다.