• Analytical Science and Technology
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• v.6 no.3
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• pp.313-318
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• 1993

The rose petal tissue biosensor has been constructed by immobilizing New carina rose tissue. Optimum conditions for the determination of urea were investigated using this sensor. Selectivity and life time of this sensor were also obtained. As a result, the biosensor showed the optimum response characteristics in 0.20M phosphate buffer solution at pH 8.0, $37^{\circ}C$ and 50mg of tissue amounts. This sensor was linear from $9.0{\times}10^{-5}$ to $4.0{\times}10^{-3}M$ urea with a slope of 42mV/decade. The limit of detection and response time are $7.0{\times}10^{-5}M$ and 17~19 min.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.66-74
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• 2023

In this study, a new potentiometric sensor selective to copper(II) ions was developed and characterized. The developed sensor has a polymeric membrane and contains 4.0% electroactive material (ionophore), 33.0% poly(vinyl chloride) (PVC), 63.0% bis(2-ethylhexyl)sebacate (BEHS) and 1.0% potassium tetrakis(p-chlorophenyl)borate (KTpClPB). This novel copper(II)-selective sensor exhibits a Nernstian response over a wide concentration range from 1.0×10^-6 to 1.0×10^-1 mol L^-1 with a slope of 29.6 (±1.2) mV decade^-1, and a lower detection limit of 8.75×10-7 mol L^-1. The sensor, which was produced economically by synthesizing the ionophore in the laboratory, has a good selectivity and repeatability, fast response time and stable potentiometric behaviour. The potential response of the sensor remains unaffected of pH in the range of 5.0-10.0. Based on the analytical applications of the sensor, we showed that it can be used as an indicator electrode in the quantification of Cu²⁺ ions by potentiometric titration against EDTA, and can also be successfully utilized for the determination of copper(II) ions in different real samples.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.154-160
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• 1990

Hydroxypropyl methacrylate polymeric membranes having tertiary amine moiety were prepared to control the release rate of insulin in response to the concentration of glucose. Hydroxypropyl methacrylate was copolymerized with N, N'-diethylaminoethylacrylate. Its water content was increased with decreasing the pH of the medium and was reversible with variation of the pH of the medium. The permeation coefficient of insulin through copolymer membrane was also increased with decreasing the pH of the medium. Combining this copolymer membrane and the glucose oxidase immobilized membrane as a sensor for glucose, composite membrane was prepared. The permeability of this composite membrane was increased with addition of glucose.

• Analytical Science and Technology
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• v.14 no.3
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• pp.286-289
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• 2001

The effect of pH and the substrate concentration on the sensing ability of the chicken peroxidase enzyme electrode was examined quanititatively. Using the new Michaelis-Menten equation, to which pH concept was introduced, enabled to calculate all kinds of dissociation constant related to chicken peroxidase and subsequently to determine the optimum pH of the sensor.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1762-1765
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• 2004

This paper suggest the field test method of PD UHF sensor's sensitivity for a high voltage GIS and prove a reliability of the field test method through the test results of UHF sensor.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.956-958
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• 1999

We designed and fabricated p-type MOSFETs with floating gate in n-type well lesion and examined their photo characteristics. The fabricated MOBFETs showed a high photo-respsonse characteristics, indicating a possibility as a photo sensor. The structures of MOSFETs were changed as to the number of gate and channel. As the number of channel increased, the induced current by light source s increased. However, the effect of the number of gate was negligble on the photo-response characteristics of the device.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.121-124
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• 2004

This paper suggest the field test method of PD UHF sensor's sensitivity for a high voltage GIS and prove a reliability of the field test method through the test results of UHF sensor.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2979-2983
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• 2009

Nanowires of polytetrakis(o-aminophenyl)porphyrin (PTAPPNW) were fabricated by electrochemical polymerization with the cyclic voltammetric method in anodic aluminum oxide (AAO) membranes. The glassy carbon electrode (GCE) modified by PTAPPNW, single-walled carbon nanotubes (SWNT) and Nafion as a binder was investigated with voltammetric methods in a phosphate buffer saline (PBS) solution at pH 7.4. The PTAPPNW + SWNT + Nafion/GCE exhibited strongly enhanced voltammetric and amperometric sensitivity towards hydrogen peroxide ($H_2O_2$), which shortened the response time and enhanced the sensitivity for $H_2O_2$ determination at an applied potential of 0.0 V by amperometric method. The PTAPPNW + SWNT + Nafion/GCE can be used to monitor $H_2O_2$ at very low concentrations in biological pH as an efficient electrochemical $H_2O_2$ sensor.

• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.266-272
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• 2001

A coil-type capacitive sensor on which the deterioration of the car engine oil can be in situ measured, has been developed. The sensor was designed to get over 10 pF at the limited space on the drain hole of the oil pan. The design factors for stable capacitance measurement such as coil diameter and winding condition, materials and configuration of the coil former, and shielding method, etc., were known by both computer simulation and experimental investigations. The dielectric properties measured by several sensors for an used sample oil were consisted within 0.25%. The sensor installed on the car having severe vibration, temperature and humidity fluctuation, even electromagnetic noise, has shown very distinguishable results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.4
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• pp.325-329
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• 2013

Carbon nanotubes(CNT) have excellent electrical, chemical stability and mechanical properties. These can be used in a variety of fields. MWCNT are extremely sensitive for minute changes in the ambient gas, namely, their sensing properties varies greatly with the absorption of gas such as NOx and $H_2$. We investigate the electrical properties of CNTs and make a NOx gas sensor based on Multi-walled carbon nanotubes (MWCNT) materials. We obtained the NOx gas sensor of MWCNT based on P-type Si wafer that has the resistivity of $1.667{\times}10^{-1}[{\Omega}{\cdot}cm]$. We knew that the sensitivity of sensor decreased with increasing of NOx gas concentration. And the sensitivity of sensor shows the largest value at $20^{\circ}C$. The sensitivity of sensor decrease with increasing the temperature. Also absorption energy of NOx gas molecule on the MWCNT surface decreases with increasing concentration of NOx gas.