• Journal of the Korean Chemical Society
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• v.39 no.1
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• pp.57-65
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• 1995

The electrochemical reduction of methylene blue (MB) in 1.0${\times}$10-2 M KNO3 aqueous solution was investigated by direct current (DC), differential pulse (DP) polarography, cyclic voltammetry (CV) and controlled potential coulometry (CPC). The electrode reduction of melthylene blue was processed CE reaction mechanism by two electrons transfer at the first reversible wave (- 0.18 volts vs. Ag/AgCl). MB was strongly adsorbed on the stationary mercury electrode and the reduction product of conptrolled potential electrolysis was rapidly auto-oxidized in air to the original methylene blue. Upon the basis of interpretation of cyclic voltammogram with pH change, possible CE electrode reaction mechanism was suggested.

• Journal of the Korean Chemical Society
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• v.38 no.3
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• pp.234-240
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• 1994

Square-wave voltammetric behavior for uranium(VI)-cupferron complex was studied in 0.1 M acetate buffer solution(pH5.0). The optimum condition for square-wave voltammetric analysis of uranium was also investigated. The reduction of uranium(VI)-cupferron complex was found to be irreversible and only uranium(VI)-cupferron complex was adsorbed on the electrode surface during the deposition time. Detection limit of uranium(VI) was 7.9nM(2 ppb) where the deposition time was 30sec at -0.1 V vs. Ag/AgCl. The amount of uranium(VI)-cupferron complex adsorbed on the electrode surface was ${\Gamma}_{max} = (4.9{\pm}0.3){\times}10^{-10} mol{\cdot}cm^{-2}$.

• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.579-587
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• 2015

To support the use of nuclear power as a sustainable electric energy generating technology, long-term supply of uranium is very important. The objective of this research is to investigate the use of new adsorbent material for cost effective uranium extraction from seawater. An activated carbon-based adsorbent material is developed and tested through an electrosorption technique in this research. Adsorption of uranium from seawater by activated carbon electrodes was investigated through electrosorption experiments up to 300 minutes by changing positive potentials from +0.2V to +0.8V (vs. Ag/AgCl). Uranium adsorption by the activated carbon electrode developed in this research reached up to 3.4 g-U/kg-adsorbent material, which is comparable with the performance of amidoxime-based adsorbent materials. Electrosorption of uranium ions from seawater was found to be most favorable at +0.4V (vs. Ag/AgCl). The cost of chemicals and materials in the present research was compared with that of the amidoxime-based approach as part of the engineering feasibility examination.

• Korean Journal of Crystallography
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• v.19 no.1
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• pp.21-24
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• 2008

The title complex [Pt(dppe)($NO_3$)($CF_3SO_3$)] (dppe=1,2-bis(diphenylphosphino)ethane, $Ph_2PCH_2CH_2PH_2$) was prepared by sequentially treating [Pt(dppe)$Cl_2$] with 1 equiv of $AgNO_3$ and 1 equiv AgOTf (OTf=$CF_3SO_3$). The Pt metal is coordinated by two phosphorous atoms of the dppe ligand, one oxygen atom of the nitrato ($NO^-_3$) ligand, and one oxygen atom of the triflato(trifluoromethylsulfonato, $OTf^-$) ligand. The coordination sphere of Pt metal can be described as a distorted square plane.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1450-1454
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• 2007

This paper presents a microfabricated Clark-type sensor which exactly can measure dissolved oxygen in the cell containing solution. We designed, fabricated, and characterized a microfabircated Clark-type oxygen sensor for measuring dissolved oxygen. The microfabricated oxygen sensor consists of 3-electrodes on a glass substrate, a FEP (Fluorinated ethylene propylene) oxygen-permeable membrane, and PDMS (Polydimethylsiloxane) reservoir for storing sample solution. Thin-film Ag/AgCl was employed as a reference electrode and its durability was verified by obtaining a stable open circuit potential for 2 hours against a commercial Ag/AgCl electrode and a stable cyclic voltammetry curve. Selectivity, response time, and linearity of the fabricated oxygen sensor were also verified well by cyclic voltammetry and amperometry depending. The fabricated oxygen sensor showed a 90% response time of 40sec and an excellent linearity with a correlation coefficient of 0.994.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.276-277
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• 2007

본 논문에서는 미량의 세포를 포함한 용액 내에서 세포의 산소호흡량을 측정하기 위해 FEP(Fluorinated Ethylene Propylene)를 멤브레인으로 사용한 Clark-type 센서를 제안하였다. 제안된 Clark-type 센서는 3-전극 시스템을 구성하는 유리 기판, 산소를 선택적으로 투과 시키는 FEP 멤브레인과 세포를 담을 수 있는 PDMS reservoir로 구성된다. 산소 센서의 3-전극 시스템에서 작업 전극과 상대 전극으로는 Au, 기준 전극으로는 Ag/AgCl을 사용하였다. 기준 전극은 Ag 전극을 0.1M KCl/Tris-HCl 용액에서 chlorination하여 표면에 AgCl이 형성되도록 하였고, OCP(Open Circuit Potential) test를 수행한 결과 2시간 동안 안정적인 OCP 특성을 보여 좋은 내구성을 가짐을 확인하였다. 또한, 산소 유무에 따른 cyclic voltammetry 그래프의 차이를 확인하고, amperometry로 감도 및 반응 시간, 선형성을 측정/분석하였다. 제작된 산소 센서는 40초의 90% 반응 시간과 0.994의 아주 좋은 선형 상관계수를 보여주었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.101-104
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• 2002

Abstract We give pressure stimulation into organic thin films and then manufacture a device under the accumulation condition that the state surface pressure is 10[mN/m]. In processing of a device manufacture, we can see the process is good from the change of a surface pressure for organic thin films and transfer ratio of area per molecule. The structure of manufactured device is Au/Poly-${\gamma}$ Benzyl $_D$-Glutamate/Al; the number of accumulated layers is 1, 3, 5 and 7. Also, we then examined of the MIM device by means of I-V. The I-V characteristic of the device is measured from 0 to +2[V]. We determined electrochemical measurement by using cyclic voltammetry with a three-electrode system. LB film accumulated by monolayer on an ITO. In the cyclicvoltammetry, An Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode measured in $LiBF_4$ solution, stable up to 0.9V vs. Ag/AgCl.

• Journal of Surface Science and Engineering
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• v.51 no.4
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• pp.237-242
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• 2018

We report on the fabrication and photoelectrochemical (PEC) properties of a ZnO nanorod array structure as an efficient photoelectrode for hydrogen production from sunlight-driven water splitting. Vertically aligned ZnO nanorods were grown on an indium-tin-oxide-coated glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which was formed by thermally oxidizing a sputtered Zn metal thin film. The structural and morphological properties of the synthesized ZnO nanorods were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated ZnO nanorod photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the vertically aligned ZnO nanorod photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., $0.65mA/cm^2$ at 0.8 V vs Ag/AgCl in a 1 mM $Na_2SO_4$ electrolyte. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs Ag/AgCl, which made the device self-powered.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2926-2936
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• 2021

Rare-earth (RE) industries generate a massive amount of radioactive residue containing high thorium concentrations. Due to the fact that thorium is considered a non-economic element, large volume of these RE processed residues are commonly disposed of without treatment. It is essential to study an appropriate treatment that could reduce the volume of waste for final disposition. To this end, this research investigates the applicability of carbon-based adsorbent in separating thorium from aqueous phase sulphate is obtained from the cracking and leaching process of solid rare-earth by-product residue. Adsorption of thorium from the aqueous phase sulphate by carbon-based electrodes was investigated through electrosorption experiments conducted at a duration of 180 minutes with a positive potential variable range of +0.2V to +0.6V (vs. Ag/AgCl). Through this research, the specific capacity obtained was equivalent to 1.0 to 5.14 mg-Th/g-Carbon. Furthermore, electrosorption of thorium ions from aqueous phase sulphate is found to be most favorable at a higher positive potential of +0.6V (vs. Ag/AgCl). This study's findings elucidate the removal of thorium from the rare-earth residue by carbon-based electrodes and simultaneously its potential to reduce disposal waste of untreated residue.

• Bulletin of the Korean Chemical Society
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• v.8 no.4
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• pp.225-230
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• 1987

The redox properties of 2-mercaptopyridine N-oxide (mpno) and its oxovanadium complex, $VO (mpno)_2$ have been studied by the use of polarography and cyclic voltammetry. The radical anion of mpno is generated in acetone and is adsorbed to the electrode to form an adsorption wave at -0.21 V vs Ag/AgCl electrode. The normal wave appeared at -0.50 V is attributed to the formation of radical anion. The $VO (mpno)_2$ exhibits one oxidation wave at +0.57 V, and two reduction waves at -1.07 V and -1.76 V vs. Ag/AgCl electrode; the oxidation is fully reversible one-electron process ($VO (mpno)_2\;{\leftrightarrow}\;VO(mpno)_2^+ + e).$ The reduction wave at -1.07 V is quasireversible and is arised from the formation of $VO (mpno)_2^-.$ The second reduction wave at -1.76 V is irreversible and this reduction process consists of two one-electron steps. The sulfur containing ligands seem to enhance the stability of lower oxidation state of vanadium while the oxygen or nitrogen donor of the ligands stabilize the higher oxidation state of vanadium when comparisons are made among several oxovanadium complexes.