• 한국분말재료학회지
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• 제15권5호
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• pp.393-398
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• 2008

Trace analysis of Cd and Pb at surface modified thick film graphite electrode with Bi nanopowder has been carried out using square-wave anodic stripping voltammetry (SWASV) technique. Bi nanopowder synthesized by gas condensation (GC) method showed the size of $50{\sim}100$ nm with BET surface area, $A_{BET}=6.8m^{2}g^{-l}$. For a strong adhesion of the Bi nanopowder onto the screen printed carbon paste electrode, nafion solution was added into Bi-containing suspension. From the SWASV, it was found that the Bi nanopowder electrode exhibited a well-defined responses relating to the oxidations of Cd and Pb. The current peak intensity increased with increasing concentration of Cd and Pb. From the linear relationship between Cd/Pb concentrations and peak current, the sensitivity of the Bi nanopowder electrode was quantitatively estimated. The detection limit of the electrode was estimated to be $0.15{\mu}g/l$ and $0.07{\mu}g/l$ for Cd and Pb, respectively, on the basis of the signal-to-noise characteristics (S/N=3) of the response for the $1.0{\mu}g/l$ solution under a 10 min accumulation.

• Journal of Biosystems Engineering
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• 제41권2호
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• pp.75-84
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• 2016

Purpose: In-situ water quality monitoring based on ion-selective electrodes (ISEs) is a promising technique because ISEs can be used directly in the medium to be tested, have a compact size, and are inexpensive. However, signal drift can be a major concern with on-line management systems because continuous immersion of the ISEs in water causes electrode degradation, affecting the stability, repeatability, and selectivity over time. In this study, a computer-based nitrate monitoring system including automatic electrode rinsing and calibration was developed to measure the nitrate concentration in water samples in real-time. Methods: The capabilities of two different types of poly(vinyl chloride) membrane-based ISEs, an electrode with a liquid filling and a carbon paste-based solid state electrode, were used in the monitoring system and evaluated on their sensitivities, selectivities, and durabilities. A feasibility test for the continuous detection of nitrate ions in water using the developed system was conducted using water samples obtained from various water sources. Results: Both prepared ISEs were capable of detecting low concentrations of nitrate in solution, i.e., 0.7 mg/L $NO_3-N$. Furthermore, the electrodes have the same order of selectivity for nitrate: $NO_3{^-}{\gg}HCO_3{^-}$ > $Cl^-$ > $H_2PO_4{^-}$ > $SO{_4}^{2-}$, and maintain their sensitivity by > 40 mV/decade over a period of 90 days. Conclusions: The use of an automated ISE-based nitrate measurement system that includes automatic electrode rinsing and two-point normalization proved to be feasible in measuring $NO_3-N$ in water samples obtained from different water sources. A one-to-one relationship between the levels of $NO_3-N$ measured with the ISEs and standard analytical instruments was obtained.

• 센서학회지
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• 제29권4호
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• pp.232-236
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• 2020

Three-dimensional (3D) multilayered Pt electrodes were fabricated to develop a porous electrode using a pattern-transfer printing process. The Pt thin films were deposited using a transferred sputtering pattern having a 250 nm line width on the substrate, and the uniform line patterns were efficiently transferred using our proposed method. Temperature-programmed desorption (TPD) analyses were used to evaluate the porosity of the electrodes. It was possible to distinguish between two resolved maxima at 168 and 227 ℃, which could be described in terms of desorption reactions on the Pt (111) planes. The results of the TPD analysis of the 3D and multilayered Pt electrodes prepared through transfer printing were compared to those of an electrode fabricated through screen printing using a commercial Pt-carbon paste commonly used as porous electrodes. It was confirmed that the 3D multilayered electrodes exhibited a desorption concentration approximately 100 times higher than that of the Pt-carbon composite electrode, and the desorption concentration increased by approximately 0.02 mg/mol per layer. The 3D multilayered electrode effectively functions as a porous electrode and a catalyst.

• 대한전자공학회논문지SD
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• 제45권5호
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• pp.12-18
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• 2008

본 연구는 PC(polycarbonate) 기판 위에 소스(source)/드레인(drain) 전극으로 Ag 페이스트를 스크린 인쇄하여 OTFT(organic thin film transistor)를 제작하였다. 또한 이렇게 제작된 OTFT를 적용하여 OTFT-OLED(organic light emitting diode) 어레이를 제작하였으며 OTFT의 소스 및 드레인 전극과 더불어 데이터 배선전극을 Ag 페이스트를 이용하여 형성하였다. Ag 페이스트는 스크린 마스크의 mesh에 따라 325 mesh용과 500 mesh용을 사용하였으며, 325 mesh용 페이스트는 선폭 60 ${\mu}m$, 500 mesh용 페이스트는 선폭 40 ${\mu}m$까지 인쇄가 가능하였다. 그리고 면저항은 각각 $60m{\Omega}/\square,\;133.1m{\Omega}/\square$이었다. 제작된 OTFT의 성능은 이동도가 자각 0.35 $cm^2/V{\cdot}sec$와 0.12 $cm^2/V{\cdot}sec$, 문턱전압 -4.7 V와 0.9 V이었으며, 전류 점멸비는 ${\sim}10^5$이었다. OTFT-OLED 어레이는 인쇄성이 우수한 500 mesh용 Ag 페이스트를 사용하였으며 OTFT의 채널길이를 50 ${\mu}m$로 설계하여 제작하였다. OTFT-OLED 어레이의 화소는 2개의 OTFT, 1개의 캐패시터 그리고 1개의 OLED로 구성하였고, 크기는 $2mm{\times}2mm$이며, 해상도는 $16{\times}16$ 이다. 제작된 어레이는 일부 불량 화소를 포함하고 있지만 능동형 모드로 동작함을 확인할 수 있었다.

• 공업화학
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• 제18권4호
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• pp.356-360
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• 2007

나노 다공질 $TiO_2$ 전극막, 광 감응형 염료, 전해질 그리고 상대전극으로 구성된 염료감응형 태양전지(Dye-Sensitized Solar Cells, DSSCs)는 최근에 많은 관심을 받아오고 있다. 염료감응형 태양전지에서 $TiO_2$ 전극막은 태양광의 흡수량을 증가시키기 위해 가능한 많은 양의 Ru 착물을 표면에 흡착시켜야 하는데 이를 위해 높은 비표면적과 나노 다공성 입자로 구성된 광전극이 요구된다. 또한 에너지 전환 효율을 증가시키기 위한 방법으로 $TiO_2$ 페이스트의 제작시 산을 첨가 후 열처리하는 방법이 보고되고 있다. 이 논문에서는 산이 첨가된 페이스트로 제조한 $TiO_2$ 광전극이 염료감응형 태양전지의 에너지 변환 효율에 미치는 영향을 체계적으로 이해하기 위해 FE-SEM, XPS, EXAFS 그리고 AFM 등을 이용하여 제조된 광전극의 물리적 화학적 특성을 조사하였다. 또한 광전류-전압 곡선으로부터 산처리된 페이스트를 이용하여 제조한 염료감응형 태양전지의 에너지 전환효율을 평가하였다. 산처리된 페이스는 염료감응형 태양전지의 에너지 전환효율에 크게 영향을 미침을 알 수 있었다.

• 한국전기전자재료학회논문지
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• 제21권6호
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• pp.524-529
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• 2008

In this paper, in order to develop low loss multilayer actuator, piezoelectric properties of PZW-PMN-PZT multilayer actuator sintered at $900^{\circ}C$ low temperature were investigated according to the number of multilayer. The multilayer actuator was fabricated using tape casting method and used pure Ag internal electrode. The density above $8.0\;g/cm^3$ was obtained at all specimens. With increasing number of multilayer, effective electromechanical coupling factor($k_{eff}$) was increased. $k_{eff}$ of multilayer actuator shows the maximum value of 0.283 at 11 layers actuator. However, effective mechanical quality factor(Qm') was decreased according to the increase of number of multilayer. The Qm' of multilayer actuator showed the maximum value of 920 at 5 layers actuator.

• 한국세라믹학회지
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• 제28권2호
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• pp.101-108
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• 1991

0.2 mo1% La doped BaTiO3 samples were prepared by a wet chemical process (Pechini process) and electrical conductivity were measured from annealing temperatures(800-110$0^{\circ}C$) to room temperature continuously. 2 probe I-V characteristics showed that Pt electrodes were non-ohmic below about 80$0^{\circ}C$ for Ladoped sample. I-V curves showed varistor behavior and breakdown voltages showed PTC-like behavior. AC complex impedance of 0.2 La and 0.05 Mn mo1% doped BaTiO3 samples with three different electrodes (electroless Ni, Pt, Ag electrodes) were measured with temperature variation. Complex impedance plots showed that the samples with electroless Ni electrodes have negligible electrode resistance. Samples with Ag or Pt paste electrodes showed large electrode resistance. PTC effect, which is defined as the ratio of maximum resistance to minimum resistance, was found to be less than 10 for 0.2 mo1% La doped dense sample however greater than 105 with codoping of 0.05 mo1% Mn and 0.2 mol% La.

• 한국세라믹학회지
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• 제23권5호
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• pp.55-60
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• 1986

A mechanism for formation of surface reoxidation layer in Surface Boundary Layer Capacitor (SBLC) has been studied. SBLC were prepared by reduction of $BaTiO_3$ doped with $Bi_2O_3$ and electrode firing of silver paste containing $Bi_2O_3$ The apparent dielectric constant was in the order of $10^5$ and the insulation resistance larger than $10^6$$\Omega$ It can be expected that $Bi_2O_3$ dopant in $BaTiO_3$ plays the role of inhibition of grain growth and decreasing the resistivity of $BaTiO_3$. In order to confirm the process of surface reoxidation layer effects of atmosphere and annealing time in electrode sintering were investigated.

• 한국응용과학기술학회지
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• 제32권4호
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• pp.724-730
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• 2015

For ex-vivo diabetic control, the voltammetric diagnosis of glucose (GU) was conducted with a modified carbon nanotube paste electrode, using handheld analytical circuits. The optimum analytical conditions were attained within the 0.5-4.0 ug/L working range and at the 0.06 ug/L detection limit, which system was interfaced to the feedback circuits and was applied to human urine for diabetic-patient diagnosis. It can be used for ex-vivo flow control analysis, vascular flow detection and other medicinal assays. The equations of the patients' urine are y=36.65x+12.13 and $R^2=0.987$, those of the healthy person of y= 2.5x+10.9 and $R^2=0.928$ (patients: 118 ug/L; healthy person: 12.34 ug/L).

• 한국응용과학기술학회지
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• 제31권2호
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• pp.210-217
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• 2014

For ex-vivo diabetic control, the voltammetric diagnosis of glucose (GU) was conducted with a modified carbon nanotube paste electrode, using handheld analytical circuits. The optimum analytical conditions were attained within the 0.5-4.0 ug/L working range and at the 0.06 ug/L detection limit, which system was interfaced to the feedback circuits and was applied to human urine for diabetic-patient diagnosis. It can be used for ex-vivo flow control analysis, vascular flow detection, and other medicinal assays.