• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.443-446
• /
• 2006

Carbon-supported Platinum (Pt) is the potential electro-catalyst material for anodic and cathodic reactions in fuel cell. Catalytic activity of the metal strongly depends on the particle shape, size and distribution of the metal in the porous supportive network. Conventional preparation techniques based on wet impregnation and chemical reduction of the metal precursors often do not provide adequate control of particle size and shape. We have proposed a novel route for preparing nano sized Pt colloidal particles in solution by oxidation of ethylene glycol. These Pt nano particles were deposited on large surface area carbon support. The process of nano Pt colloid formation involves the oxidation of solvent ethylene glycol to mainly glycolic acid and the presence of its anion glycolate depends on the solution pH. In the process of colloidal Pt formation glycolate actsas stabilizer for the Pt colloidal particle and prevents the agglomeration of colloidal Pt particles. These mono disperse Pt particles in carbon support are found uniformly distributed in nearly spherical shape and the size distribution was narrow for both supported and unsupported metals. The average diameter of the Pt nano particle was controlled in the range off to 3 nm by optimizing reaction parameters. Transmission electron microscopy, CV and RRDE experiments were used to compliment the results.

• Journal of Electrochemical Science and Technology
• /
• v.5 no.4
• /
• pp.115-127
• /
• 2014

Cd-Pb thin films were electrodeposited from a diluted chloride solution using stainless steel rotating disc electrode. The linear sweep voltammograms of the single metallic ions show that electrodeposition of these ions was mass transfer control due to the plateau observed for different rotations at concentration (50 and 200 ppm). The voltammograms of binary system elucidate that electrodeposition process always start at cathodic potential located between the potential of individual metals. Currents transients measurements, anodic linear sweep voltammetry (ALSV) and atomic force microscopy (AFM) were used to characterize the electrocryatalization process and morphology of thin films. ALSV profiles show a differentiation for the dissolution process of individual metals and binary system. Two peaks of dissolution Cd-Pb film were observed for the binary system with different metal ion concentration ratios. The model of Scharifker and Hills was used to analyze the current transients and it revealed that Cd-Pb electrocrystalization processes at low concentration is governed by three-dimensional progressive nucleation controlled by diffusion, while at higher concentration starts as a progressive nucleation then switch to instantaneous nucleation process. AFM images reveal that Cd-Pb film electrodeposited at low concentration is more roughness than Cd-Pb film electrodeposited at high concentrated solution.

• Journal of Plant Biology
• /
• v.34 no.4
• /
• pp.261-266
• /
• 1991

The hairy root was induced form potato tuber disc by infection of a. rhizogenes. The detection of the agropine and mannopine by paper electrophoresis confirmed that induced hairy root was transformed by A. rhizogenes. The activity of peroxidase was the highest at 5 weeks and isozyme pattern of peroxidase revealed 3 cathodic bands and 2 anodic bands and new C4 band(pI 4.6) was observed at 7 weeks after cultivation in hairy root was isoelectric focusing. To study the effect of Ca2+ on cell wall formation in hairy root, channel blocker of Ca2+ was treated. The activity of $\beta$-glucan synthetase II(GS II) related to cell wall synthesis was inhibited by about 50% in diltiazem and flunarizine treatment than that of control, but stimulated in CaCl2 treatment. Therefore these results showed that Ca2+ might be an effective factor in the cell wall formation. The activity of GS II by NaF treatment was increased by about 30%. This result suggested that the activity GS II is changed through phosphorylation process.

• Journal of the Korean Institute of Gas
• /
• v.19 no.3
• /
• pp.38-43
• /
• 2015

For buried gas pipelines, cathodic protection system shall be installed to protect against corrosion. The surveys of pipe-to-soil potentials for the gas pipelines should be carried out at the test box more than once a year. In urban, the test box is usually located on the driveway, therefore, it is difficult to measure the potentials. That is, traffic control is needed when carrying out the measurements of the potentials on daytime, or measurements of pipe-to-soil potentials at the test box located on the driveway have to be carried out in the late night when the traffic is light. We have developed remote potential monitoring system using the solid reference electrode and the wireless communication technology for the purpose of removing above problems. We have installed the developed solid reference electrodes at a site and monitored the potentials by wireless communication. Measured potential values were transferred to the server in office and analyzed. We have found the pipe-to-soil potentials transferred to the web server make no difference to the potentials measured directly on the site.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.101-109
• /
• 2005

In order to produce only a pH-controlled solution without discharging any unused solution, this work has developed a continuous electrolytic system with a pH-adjustment reservoir being placed before an ion exchange membrane-equipped electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, some portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and some other portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through other counter chamber with its pH being controlled as acid or base. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between anode and cathode and its consequently-occurring non-charge equilibriums and electrolytic water- split reactions in the anodic and cathodic chambers.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.6
• /
• pp.1221-1228
• /
• 2005

Carbon electrode was applied to a wastewater treatment system as biofilm media. The spatial distribution of heterotrophic bacteria in aerobic wastewater biofilm grown on carbon electrode was investigated by scanning electron microscopy, atomic force microscopy, and biomass measurement. Five volts of electric oxidation and reduction potential were charged to the carbon anode and cathode of the bioelectrochemical system, respectively, but were not charged to electrodes of a conventional system. To correlate the biofilm architecture of bacterial populations with their activity, the bacterial treatment efficiency of organic carbons was measured in the bioelectrochemical system and compared with that in the conventional system. In the SEM image, the biofilm on the anodic medium of the bioelectrochemical system looked intact and active; however, that on the carbon medium of the conventional system appeared to be shrinking or damaging. In the AFM image, the thickness of biofilm formed on the carbon medium was about two times of those on the anodic medium. The bacterial treatment efficiency of organic carbons in the bioelectrochemical system was about 1.5 times higher than that in the conventional system. Some denitrifying bacteria can metabolically oxidize $H_{2}$, coupled to reduction of $NO_{3}^{-}\;to\;N_{2}$. $H_{2}$ was produced from the cathode in the bioelectrochemical system by electrolysis of water but was not so in the conventional system. The denitrification efficiency was less than $22\%$ in the conventional system and more than $77\%$ in the bioelectrochemical system. From these results, we found that the electrochemical coupling reactions between aerobic and anaerobic reactors may be a useful tool for improvement of wastewater treatment and denitrification efficiency, without special manipulations such as bacterial growth condition control, C/N ratio (the ratio of carbon to nitrogen) control, MLSS returning, or biofilm refreshing.

• Journal of the Korean Vacuum Society
• /
• v.11 no.1
• /
• pp.8-15
• /
• 2002

Tetrahedral amorphous carbon(ta-C) films were deposited by the filtered vacuum arc(FVA) process. The FVA process has many advantages such as high ionization ratio and the ion energy, which is suitable for dense amorphous carbon film deposition. However, the energy of the carbon ion cannot be readily controlled by manipulating the arc source parameters. In order to control the film properties in wide range, we investigated the dependence of the film properties on the substrate bias voltage. The mechanical properties and the density of the film exhibit the maximum values at about -100 V of the bias voltage. The maximum values of hardness and density were respectively 54$\pm$3 GPa and 3.6$\pm$0.4 g/㎤, which are 3 to 5 times higher than those of the films deposited by RF PACVD or ion beam process. The details of the atomic bond structure were analysed by Raman and NEXAFS spectroscopy. The change in the film properties for various bias voltages could be understood in the view of the $sp^2$ and $sp^3$ bond fraction in the deposited films.

• Corrosion Science and Technology
• /
• v.7 no.1
• /
• pp.16-21
• /
• 2008

A non-phosphorous program employing an alkyl epoxy carboxylate (AEC) has been successfully applied to petrochemical and other large industrial open recirculating cooling water systems. AEC is a patented non-phosphorous calcium carbonate scale inhibitor that has demonstrated better scale inhibition abilities than traditional organic phosphonates. In addition to its antiscalant properties, AEC inhibits carbon steel corrosion when used at high dosages. AEC can be combined with zinc to form a non-phosphorous program with very low levels of phosphate to provide an environmentally acceptable program. In actual applications, the total phosphate developed in the cooling system from cycling the makeup is below 1 ppm as $PO_4$. This level has complied with the highest standards of wastewater discharge limitations. The performance of two AEC/Zinc applications is reviewed. In both cases excellent corrosion and scale control were achieved with AEC/Zinc programs. One case history details the performance with a low hardness water (100 ppm calcium, as $CaCO_3$) operating at 8-10 cycles of concentration. The corrosive nature of the water and the long retention time of the system stressed both the corrosion and scale control capabilities of the program. The second case history demonstrates the performance of the program with a moderate hardness water (400-600 ppm calcium, as $CaCO_3$), but under harsh conditions of high temperature and low flow. The AEC/zinc combination has been found to be highly effective in controlling the corrosion of ferrous metals. AEC can provide good corrosion inhibition at high concentrations, while zinc is known to be an excellent cathodic inhibitor. The combination of the two inhibitors not only provides a synergistic blend that is effective over a wide range of operating conditions, but also is environmentally friendly.

• Corrosion Science and Technology
• /
• v.18 no.6
• /
• pp.277-284
• /
• 2019

External corrosion control of buried pipe can be achieved by the combination of barrier coating and cathodic protection. Coating damage and deterioration can be induced by many reasons; damage during handling and laying, enhanced failure at low temperatures, failure during commissioning and operation, disbanding due to inadequate surface cleaning, rock penetration during installation and service etc. This work focused on the effect of survey conditions on the reliability of coating flaw detection of buried pipes. The effects of applied voltage and anode location on the detection reliability of coating flaw of buried pipe in soil with the resistivity of ca. 25.8 kΩ·cm were discussed. Higher applied voltage increased the detection reliability, regardless of buried depth, but deeper burial depth reduced the reliability. The location of the anode has influenced on the detection reliability. This behaviour may be induced by the variation of current distribution by the applied voltage and buried depth. From the relationship between the applied voltage and reliability, the needed detection potential to get a desire detection reliability can be calculated to get 100% detection reliability using the derived equation.

• The Korean Journal of Physiology and Pharmacology
• /
• v.21 no.5
• /
• pp.555-563
• /
• 2017

Electrical stimulation through retinal prosthesis elicits both short and long-latency retinal ganglion cell (RGC) spikes. Because the short-latency RGC spike is usually obscured by electrical stimulus artifact, it is very important to isolate spike from stimulus artifact. Previously, we showed that topographic prominence (TP) discriminator based algorithm is valid and useful for artifact subtraction. In this study, we compared the performance of forward backward (FB) filter only vs. TP-adopted FB filter for artifact subtraction. From the extracted retinae of rd1 mice, we recorded RGC spikes with $8{\times}8$ multielectrode array (MEA). The recorded signals were classified into four groups by distances between the stimulation and recording electrodes on MEA (200-400, 400-600, 600-800, $800-1000{\mu}m$). Fifty cathodic phase-$1^{st}$ biphasic current pulses (duration $500{\mu}s$, intensity 5, 10, 20, 30, 40, 50, $60{\mu}A$) were applied at every 1 sec. We compared false positive error and false negative error in FB filter and TP-adopted FB filter. By implementing TP-adopted FB filter, short-latency spike can be detected better regarding sensitivity and specificity for detecting spikes regardless of the strength of stimulus and the distance between stimulus and recording electrodes.