• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.393-393
• /
• 2011

We investigated the electronic structures of a poly sodium 4-styrensulfonate intercalated graphite oxide (PSSGO) electrode and a precursor graphite oxide (GO) electrode using X-ray absorption spectroscopy (XAS). Both electrodes were obtained from electrochemical cells. We found that in the C K-edge XAS spectra the ${\pi}^*$ state intensity originating from the sp2 hybridization of graphite decreases predominantly in the graphite oxide and PSSGO electrodes. This indicates that the negatively charged electrolyte ion (BF4-) is absorbed onto the electrodes and is transferred to the ${\pi}^*$ state of the both electrodes. The analysis of their F K-edge spectra reveals that more BF4- ions were found in the PSSGO electrode than in the graphite oxide electrode. This indicates that more electrolyte ions are absorbed in the PSSGO than in the graphite oxide electrode. We argue that this is the main reason why PSSGO cells have higher capacitance, higher energy density, and higher power density when compared to the graphite oxide cells. We also found that BF4- is the primary working ion that can be inserted into the interlayers of the PSSGO electrode.

• Journal of the Korean institute of surface engineering
• /
• v.53 no.5
• /
• pp.213-218
• /
• 2020

Composite material of the graphene ball (GB) inserted graphene oxide (GO) sheet for a supercapacitor electrode was studied. Chemical vapor deposition (CVD) process used to make GBs on the silicon oxide nanoparticles. The GBs mixed into the GO sheets to make GOGB and reduced it to create a reduced GOGB(RGOGB) composite. The RGOGB composite electrode had a large surface area and improved electrochemical properties. Specific capacitance of the RGBGO composite electrode was higher over 20 times than a pure GO and GOGB electrode in cyclic voltammetry(CV) tests, and the Z' and Z" impedance measured by an electrochemical impedance spectrometry(EIS) also low. So, the RGBGO composite electrode would use effectively to expand a performance of supercapacitor.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.10
• /
• pp.1792-1796
• /
• 2007

Insulating effects on Au electrode according to the thickness and density of coated materials are well-known. To do electrochemical immunoassay reproducibly the glod electrode would be coated with self-assembled monolayers and antobodies. To get reproducibility, the antobody monolayer should be packed at highest density so that the amount of immobilized antibody at defined area should be the same. The calix[4]crown-5 SAMs could provide the basis for the antibodies to be immobilized reproducibly and at highest density. But the insulating effect would be highest too. We proved that the compactly packed protein monolayers on SAMs inhibited the electron transfer by block the free shuttling of redox molecules. The inhibition was minimized by inserting redox molecules in between the proteins during immobilization process. In this paper, we demonstrated that the calix[4]crown-5 SAMs would provide the protein monolayers with highest density and new method to minimize the insulating effect by inserted redox molecules in between the compactly packed protein monolayers.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.512-513
• /
• 2013

Space and time resolved discharge images from an atmospheric pressure non-thermal Ar plasma jet have been observed by a ICCD camera to investigate the electron temperatures. Plasma jet device consisting of a syringe electrode inserted into a glass tube has been introduced. A high voltage is applied to the syringe electrode. The syringe needle has an outer diameter of 1.8 mm, an inner diameter of 1.3 mm, and a total length of 39.0 mm. The needle is inserted into a glass tube of outer diameter 2.4 mm and inner diameter 2.0 mm, and a total length of 80.0 mm. The Ar plasma propagation speed on the cathode has been shown to be about 2.1 km/s at input discharge voltage of 3.6 kV, discharge current of 19.9 mA and driving frequency of about 45 kHz. Particularly, the electron temperature in plasma jet were found to be about 1.8 eV at input discharge voltage of 3.6 kV and driving frequency of 45 kHz, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.1
• /
• pp.28-33
• /
• 2015

The needle electrode is inserted into the cross-linked polyethylene(XLPE) which is the ultra high voltage cable for electric power. By changing the tilt of the needle electrode, we investigated how the void and the thickness of the insulating layer influence the partial discharge(PD) characteristics and the insulating breakdown. In order to investigate the PD characteristics, The XLPE cable was used to the specimens and the tungsten electrode was used with the needle electrode. And the inner semi-conductive layer material of XLPE cable was used with the negative electrode by bonding with the use of conduction tape. The size of the specimens was manufactured to be $16{\times}40{\times}30[mm^3]$. We confirmed the effect on changing the PD characteristics according to the changing voltage and the tilt of the electrode after applying the voltage on the electrode from 1[kV] to 40[kV] at room temperature. In the PD characteristics, it was confirmed that the PD current of air void specimens with tilt was unstable more than that of no void specimens with tilt. It was also confirmed that the breakdown voltage was decreased because the effect of air void is more active than the change of the needle electrode tilt in the specimen with air void inside the insulation.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.51-54
• /
• 2004

We have developed a new PDP cell structure called MARI(${\underline{M}}ulti$ ${\underline{A}}node$ for ${\underline{R}}eduction$ of ${\underline{I}}onic$ effect) and new driving scheme achieving a high luminous efficacy. The MARI PDP has middle electrode inserted between X and Y main electrodes. In the MARI PDP, reset and scan voltage is applied to middle electrode and sustain voltage is applied to X and Y electrode. Using a long gap sustain discharge we accomplished a high luminous efficacy. And we developed 42”full panel adopting MARI structure and new driving scheme and attained luminous efficacy of 2.35lm/W.

• Transactions on Electrical and Electronic Materials
• /
• v.6 no.4
• /
• pp.154-158
• /
• 2005

Organic molecules have many properties that make them attractive for electronic applications. We have been examining the progress of memory cell by using molecular-scale switch to give an example of the application using both nano scale components and Si-technology. In this study, molecular electronic devices were fabricated with amino style derivatives as redox-active component. This molecule is amphiphilic to allow monolayer formation by the Langmuir-Blodgett (LB) method and then this LB monolayer is inserted between two metal electrodes. According to the current-voltage (I-V) characteristics, it was found that the devices show remarkable hysteresis behavior and can be used as memory devices at ambient conditions, when aluminum oxide layer was existed on bottom electrode. The diode-like characteristics were measured only, when Pt layer was existed as bottom electrode. It was also found that this metal layer interacts with organic molecules and acts as a protecting layer, when thin Ti layer was inserted between the organic molecular layer and Al top electrode. These electrical properties of the devices may be applicable to active components for the memory and/or logic gates in the future.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.5
• /
• pp.827-832
• /
• 2008

One of the most important issues in AC PDP is luminance and luminous efficacy. To improve the luminance and luminous efficacy, new sustain electrode structure which contains long discharge gap is necessary. However, it causes a rise of firing voltage. In this experiment, a new structure is proposed in order to solve this problem. To drop the firing voltage, the hump shaped electrode is inserted into the forward area of the main discharge gap. The experimental results show that proposed structures with 160um discharge gap have high firing voltage by 38V, high luminance by 30% and high luminous efficacy by 15% compared with conventional type having 60um discharge gap. In addition, the proposed structure with hump electrode shows lower firing voltage by 24V compared with the test panel with 160um discharge gap which doesn't have hump electrode though they have similar luminous efficacy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.346.1-346.1
• /
• 2014

Porous nano crystalline $TiO_2$ is currently used as a working electrode in a dye-sensitized solar cell (DSSC). The conventional working electrode is comprised of absorption layer (particle size:~20 nm) and scattering layer (particle size:~300 nm). We inserted window layer with 10 nm particle size in order to increase transmittance and specific surface area of $TiO_2$. The electrochemical impedance spectroscope analysis was conducted to analysis characterization of the electronic behavior. The Bode phase plot and Nyquist plot were interpreted to confirm the internal resistance caused by the insertion of window layer and carrier lifetime. The photocurrent that occurred in working electrode, which is caused by rise in specific surface area, increased. Accordingly, it was found that insertion of window layer in the working electrode lead to not only effectively transmitting the light, but also increasing of specific surface area. Therefore, it was concluded that insertion of window layer contributes to high conversion efficiency of DSSCs.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.4059-4062
• /
• 2012

The effect of a conductive agent on the structural and electrochemical properties of $Li_4Ti_5O_{12}$(LTO) spinel was investigated through neutron diffraction during Li intercalation and electrochemical measurements. The charging process of LTO is known as transformation of the white $(Li_3)_{8a}[LiTi_5]_{16d}O_{12}$ into a dark-colored $(Li_{3-X})_{8a}[Li_{X+Y}]_{16c}[LiTi_5]_{16d}O_{12}$ by incorporating the inserted Li into octahedral 16c sites, and the Li in tetrahedral 8a sites shifted to 16c sites. The occupancy of the tetrahedral 8a site varied with the existence of carbon in the electrode. Without carbon, the lattice parameter and cell volume of LTO decreased more notably than in the carbon-containing LTO electrode during Li insertion process. These phenomena might be attributed that the Li occupancy of the tetrahedral 8a of the LTO electrode without carbon was less than that of the carbon-containing LTO electrode.