• Transactions on Electrical and Electronic Materials
• /
• v.8 no.4
• /
• pp.182-187
• /
• 2007

The use of the pulsed electro acoustic (PEA) method allowed us to perform the direct observations of spatio-temporal charge distributions in Electric double layer capacitors (EDLCs) based on polarizable nanoporous carbonaceous electrode. The negative charge density became the maximum, about $205C/m^3$ at the region where was near to collector layer in EDLCs for case $V_{DC}=2.5V$, while the positively charged density became the maximum, about $61.1C/m^3$ at the region where it was located around the cathode layer. The performance of the best sample was found to be better in terms of the charge density (Cs) and specific energy ($E_s$) with a maximum value of ${\sim}8.4F/g$ and 26 Wh/kg. The $C_s$ obtained from the PEA method agreed well with that from the energy conversion method. The PEA measurement used here is a very useful method to quantitively investigates the spatio-temporal charge distribution in EDLCs.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.64.2-64.2
• /
• 2010

In order to improve the overall power conversion efficiency in dye-sensitized solar cells (DSSCs), it is very important to secure the sufficient surface area of photocatalytic nanoparticles layer for absorbing dye molecules. It is because increasing the amount of dye absorbed generally results in increasing the amount of light harvesting. In this work, we proposed a new method for increasing the specific surface area of photocatalytic titanium oxide ($TiO_2$) nanoparticles by using an inorganic templating method. Salt-$TiO_2$ composite nanoparticles were synthesized in this approach by spray pyrolyzing both the titanium butoxide and sodium chloride solution. After aqueous removal of salt from salt-$TiO_2$ composite nanoparticles, mesoporous $TiO_2$ nanoparticles with pore size of 2~50 nm were formed and then the specific surface area of resulting porous $TiO_2$ nanoparticle was measured by Brunauer-Emmett-Teller (BET) method. Generally, commercially available P-25 with the average primary size of ~25 nm $TiO_2$ nanoparticles was used as an active layer for dye-sensitized solarcells, and the specific surface area of P-25 was found to be ~50 $m^2/g$. On the other hand, the specific surface area of mesoporous $TiO_2$ nanoparticles prepared in this approach was found to be ~286 $m^2/g$, which is 5 times higher than that of P-25. The increased specific surface area of $TiO_2$ nanoparticles will absorb relatively more dye molecules, which can increase the short curcuit current (Jsc) in DSSCs. The influence of nanoporous structures of $TiO_2$ on the performance of DSSCs will be discussed in terms of the amount of dye molecules absorbed, the fill factor, the short circuit current, and the power conversion efficiency.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.16 no.1
• /
• pp.59-68
• /
• 1986

The purpose of this investigation was to locate the central plane of the image layer on the panoramic machine relative to a specific point on the machine. In the study of the central plane of the image layer of panoramic radiograph, using the Morrita Company PANEX-EC a series of 33 exposures were taken with the 4-5 experimental pins placed in the holes of the plastic model plate, then evaluated by human eye. The author analyzed the central plane of the image layer by Mitutoyo-A-221 and calculated horizontal and vertical magnification ratio in the central plane of the image layer determined experimentally. The results were as follows: 1. The location of the central plane of the image layer determined experimentally was to lateral, compared with manufactural central plane. 2. Horizontal magnification ratio in the central plane of the image layer determined experimentally was 9.25%. 3. Vertical magnification ratio in the central plane of the image layer determined experimentally was 9.17%.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.5
• /
• pp.552-558
• /
• 2013

In recent years the interest on flexible display has been increasing as a future display due to its bendable characteristics. An ITO(indium tin oxide) layer, which is part of a flexible display, can be broken easily while bending because it is made of brittle materials. This brittle property can cause the malfunction of flexible display. To analyze fracture characteristics of ITO layer, bending test was conducted commonly. However, it is not possible to know specific phenomena on bended ITO layer by simple bending test only. Accordingly, in this study, the FE(finite element) model is developed similarly to a real flexible display to analyze stress distribution of flexible display under bending condition, especially on ITO layer. To validate FE model, actual bending test was conducted and the test results were compared with the simulation results by measuring reaction forces during bending. By using the developed model, FE analysis about the effect of design parameter (Thickness & Young's Modulus of BL) on ITO Layer was performed. By explained FE analysis above, this research draws a conclusion of reliable design guide of flexible display, especially on ITO layer.

• Journal of the East Asian Society of Dietary Life
• /
• v.18 no.4
• /
• pp.531-538
• /
• 2008

We researched the physical, chemical, functional, textural, and manufacturing characteristics of yellow layer cake which prepared by adding different amounts of persimmon leaf powder (0, 4, 8, 12, 16%). The color of the crumbs inside the cake appeared dark, demonstrating that the L value decreased as the amount of persimmon leaf powder increased. The value of a, which corresponds to the level of redness, increased and the cake appeared dark red as the amount of persimmon leaf powder added increased; whereas, the yellowness of the cake tended to decrease as the value of b, which corresponds to the level of yellowness, gradually. As the amount of persimmon leaf powder added increased, the specific loaf volume of the cake increased, but the amount of baking loss tended to be similar at all. The textural characteristics of hardness and gumminess tended to increase, but cohesion and elasticity were not influenced by the addition of persimmon leaf powder. In the sensory test, color was rated low, but flavor, taste, and texture showed the highest score in 8% as the amount of persimmon leaf powder added increased. The general preference was highest when the persimmon leaf powder was added in the amount of 8%, and it decreased as the amount of persimmon leaf powder added increased.

• Journal of the East Asian Society of Dietary Life
• /
• v.23 no.3
• /
• pp.349-356
• /
• 2013

When making a yellow layer cake, an existing chemical leavening agent, sourdough starter powder, was used instead of using baking powder in order to produce batter where the acid agent in the baking powder was reduced using baking soda. The control group had the lowest share of the batter and therefore had the highest specific volume. In a test group, the share of SP4 was low and therefore, the specific volume was high. In terms of physiochemical characteristics, the volume, symmetry and uniform index was high in SP4 in the test group. The control group had the highest moisture content followed by SP4. In terms of texture, the control group had the lowest hardness and highest springiness. In the test group, SP4 had the lowest hardness and highest springiness. The result of the sensory evaluation indicates that SP4 had the best taste and flavor. In terms of overall preference, SP4 showed significantly higher preference overall. However, it did not show any significant difference compared to the control group.

• Journal of the Korean Electrochemical Society
• /
• v.16 no.2
• /
• pp.65-69
• /
• 2013

In order to improve capacitance of activated carbon for electric double layer capacitors, peptide bond was induced on the surface of the activated carbon by urea. Urea induced activated carbon has been stabilized through carbonization. Electrochemical characteristics was observed by cyclic voltammetry for specific capacitance, electrochemical impedance spectroscope for measuring resistance and charge-discharge for testing the cyclic ability. In the result, specific capacitance is increased about 22.9% than the activated carbon. And it shows excellent cycle performance and decreasing resistance with the introduction of nitrogen functional groups.

• Advances in Energy Research
• /
• v.7 no.1
• /
• pp.21-34
• /
• 2020

Energy storage devices have received a keen interest throughout the world due to high power consumption. A large number of research activities are being conducted on electrochemical double layer capacitors (EDLCs) because of their high power density and higher energy density. In the present study, an EDLC was fabricated using natural graphite based electrodes and ionic liquid (IL) based gel polymer electrolyte (GPE). The IL based GPE was prepared using the IL, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (1E3MITF) with the polymer poly(vinyl chloride) (PVC) and the salt magnesium trifluoromethanesulfonate (Mg(CF₃SO₃)₂ - MgTF). GPE was characterized by electrochemical impedance spectroscopy (EIS), DC polarization test, linear sweep voltammetry (LSV) test and cyclic voltammetry (CV) test. The maximum room temperature conductivity of the sample was 1.64 × 10^-4 Scm^-1. The electrolyte was purely an ionic conductor and the anionic contribution was prominent. Fabricated EDLC was characterized by EIS, CV and galvanostatic charge discharge (GCD) tests. CV test of the EDLC exhibits a single electrode specific capacitance of 1.44 Fg^-1 initially and GCD test gives 0.83 Fg^-1 as initial single electrode specific discharge capacitance. Moreover, a good stability was observed for prolonged cycling and the device can be used for applications with further modifications.

• Korean Journal of Materials Research
• /
• v.27 no.11
• /
• pp.617-623
• /
• 2017

Mesoporous carbon nanofibers as electrode material for electrical double-layer capacitors(EDLCs) are fabricated using the electrospinning method and carbonization. Their morphologies, structures, chemical bonding states, porous structure, and electrochemical performance are investigated. The optimized mesoporous carbon nanofiber has a high sepecific surface area of $667m^2\;g^{-1}$, high average pore size of 6.3 nm, and high mesopore volume fraction of 80 %, as well as a unifom network structure consiting of a 1-D nanofiber stucture. The optimized mesoporous carbon nanofiber shows outstanding electrochemical performance with high specific capacitance of $87F\;g^{-1}$ at a current density of $0.1A\;g^{-1}$, high-rate performance ($72F\;g^{-1}$ at a current density of $20.0A\;g^{-1}$), and good cycling stability ($92F\;g^{-1}$ after 100 cycles). The improvement of the electrochemical performance via the combined effects of high specific surface area are due to the high mesopore volume fraction of the carbon nanofibers.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.1 no.1
• /
• pp.114-127
• /
• 1998

A user friendly computer code(EMCOMST; Electro-Magnetic response for COMposite STructures) was developed which provides with computations of the response characteristics such as reflectance and transmittance to the incident wave angles, frequencies, composite thicknesses, ply orientations, and types of backplate as the linearly polarized transverse electro-magnetic wave is emitted to the advanced composite structures. In this investigation were reviewed the electromagnetic characteristics of the continuous orthotropic fiber-reinforced organic matrix composites with or without ferrite fillers, which are actively applied to low-weight and high-strength aircraft structures. Also were calculated the response of the three layered compound structures which have appropriately stacked above-mentioned materials as transmitting layer, absorbing layer, reflection layer, respectively under the specific thickness constraints for mechanical strength design requirements. For the composite structures presented in this study, minimum reflectance value less than -5㏈ can be obtained in the frequency range of 4 to 12 ㎓. In addition, analysis of structures attached isotropic radar absorbing materials(RAM) is facilitated by putting the material properties in the material input card entries adequately.