• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.5
• /
• pp.720-725
• /
• 2012

Sodium hypochlorite is used worldwide as a water disinfectant and in bleaching agent. Sodium hypochlorite applied to water initially undergoes hydrolysis to form free chlorine consisting of hypochlorous acid(HOCl) and hypochlorite ion($OCl^-$). For free chlorine determination, an electrochemical method is simple due to the electroactivity of free chlorine; it measures current and is free of most reagents. Amperometric free chlorine sensor has been developed with gold (Au)-based electrode. The 3-electrode free chlorine sensor whose working and counter electrodes were Pt exhibited excellent response to HClO at +400mV vs. Ag/AgCl/sat. KCl. In addition, the use of a pH error correction algorithm provided a reliable measurement of residual free chlorine in water sample without any pretreatment in the normal pH range(pH 6~8) of municipal water supply. The free chlorine sensor installed in on-line monitoring system could be used to continually monitor the level of residual free chlorine in real samples.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.8
• /
• pp.1405-1409
• /
• 2007

The potential-induced charge transfer of the dye (Bu4N)2[Ru(dcbpyH)2-(NCS)2] (N719) on Au, Ag, and Cu electrode surfaces has been examined by surface-enhanced Raman scattering (SERS) in the applied voltage range between 0.0 and ?0.8 V. N719 is assumed to have a relatively perpendicular geometry with its bipyridine ring on the metal surfaces. A strong appearance of the carboxylate band at ~1370 cm-1 indicates that the carboxyl group will likely be deprotonated on the metal surfaces. As the electric potential is shifted from ?0.8 to 0.0 V, the ν (NCS) band at ~2100 cm-1 on the electrode surfaces appears to undergo a shift in frequency and intensity change. This indicated that the charge transfer between the dye and metal electrode surfaces had occurred. Electric-field-dependent charge transfer differs somewhat depending on the type of metal surfaces as suggested from the dissimilar frequency positions of the ν (NCS) band.

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

• Bulletin of the Korean Chemical Society
• /
• v.31 no.2
• /
• pp.491-494
• /
• 2010

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.198-201
• /
• 2004

We have developed a multi-domain vertically aligned liquid crystal display (MVA-LCD) that produces natural gray-scale images even at high viewing angles. We divided each pixel into two areas and set different threshold voltages for each sub-area. A transparent electrode in a sub-area is not connected directly to the source electrodes but via the capacitance of the SiN layer. In particular, light-orange skin color appears very natural, even at a high inclination angle. The contrast ratio is over 500 in the normal direction and over 10 from any viewing angle.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.481-482
• /
• 2006

We fabricated pentacene organic thin film transistor with good uniformity. And we extracted contact resistance in organic thin film transistors from the plot of the inverse of drain current versus channel length by extrapolating the curve to a channel length of zero, and multiplying by drain-source voltage. Extracted contact resistance is about $70K{\Omega}$ at gate-drain voltage of -20 V

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2395-2397
• /
• 2005

A low voltage operated piezoelectric RF MEMS in-line switch has been realized by using silicon bulk micromachining technologies for advanced mobile/wireless applications. The developed RF MEMS in-line switches were comprised of four piezoelectric cantilever actuators with an Au contact metal electrode and a suspended Au signal transmission line above the silicon substrate. The measured operation dc bias voltages were ranged from 2.5 to 4 volts by varying the thickness and the length of the piezoelectric cantilever actuators, which are well agreed with the simulation results. The measured isolation and insertion loss of the switch with series configuration were -43dB and -0.21dB (including parasitic effects of the silicon substrate) at a frequency of 2GHz and an actuation voltage of 3 volts.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.108-111
• /
• 2003

Currently, molecular devices are reported utilizing active self-assembled monolayers containing the nitro group as the active component, which has active redox centers[1]. We confirm the electrical properties of 4,4-di(ethynylphenyl)-2'-nitro-1-benzenethiolate. To deposit the SAM layer onto gold electrode, we transfer the prefabricated Au(111) substrates into a 1mM self-assembly molecules in THF solution. Au(111) substrates were prepared by ion beam sputtering method of gold onto the silicon wafer. As a result, we measured current-voltage curve using ultra high vacuum scanning tunneling microscopy (UHV STM), I-V curve also clearly shows several current peaks between the negative bias region (-0.3958V) and the positive bias region (0.4658V), respectively.

• Journal of the Korean Chemical Society
• /
• v.63 no.1
• /
• pp.45-50
• /
• 2019

Because arsenic (As) is a chemical substance toxic to humans, there have been extensive investigations on the development of As detection methods. In this study, the electrochemical determination of As on nanoporous gold (NPG) electrodes was investigated using anodic stripping voltammetry. The electrochemical surface area of the NPG electrodes was controlled by changing the reaction times during the anodization of Au for NPG preparation, and its effect on the electrochemical behavior during As detection was examined. The detection efficiency of the NPG electrodes improved as the roughness factor of the NPG electrodes increased up to around 100. A further increase in the surface area of the NPG electrodes resulted in a decrease of the detection efficiency due to high background current levels. The most efficient As detection efficiency was obtained on the NPG electrodes prepared with an anodization time of 50 s. The effects of the detection parameters and of the Cu interference in As detection were investigated and the NPG electrode was compared to flat Au electrodes.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.4
• /
• pp.321-325
• /
• 1995

Adsorption mechanisms of diisobutyl dithiophosphinate (DIBDTPI) and diisobutyl monothiophosphinate (DIBMTPI) on gold and gold-silver alloys (80:20 and 50:50) have been studied. The adsorption mechanisms on gold-silver alloys can be explained by the EC mechanism involving an electron transfer step and a chemical reaction step. Thus, the adsorption should be controlled by the E of the electrochemical oxidation of the electrode involved and the pK of the metal collector complex. Both di- and mono- thiophosphinate adsorb on 50:50 Au-Ag alloy at lower potential than on 80:20 Au-Ag alloy surface. There are no significant differences between the reactivities of DIBDTPI and DIBMTPI with precious metals except that the dithio- compound can be oxidized to dimer on gold at high potentials, while the monothio- homologue cannot. In this regard, DIBDTPI may be a better surface active reagent for pure gold than DIBMTPI.