• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.173-180
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• 2003

Effects of the electric conductivity of particles were studied for the aggregation process of charged particles with a Brownian dynamic simulation in the free molecular regime. A periodic boundary condition was used for the calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered two extreme cases, a perfect conductor and a perfect nonconductor. The electrostatic force on a particle in the simulation cell was considered as a sum of electrostatic forces from other particles in the original cell and its replicate cells. We assumed that aggregates were only charged with pre-charged primary particles. The morphological shape of aggregates was described in terms of the fractal dimension. The fractal dimension for the uncharged aggregate was D$_{f}$= 1.761. However, the fractal dimension decreased from 1.694 to 1.360 for the case of the perfect conductor, and from 1.610 to 1.476 for the case of the perfect nonconductor, with the increase of the average number of charges on the primary particle from 0.2 to 0.3. These values were smaller than that of the centered charge case.e.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.19-23
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• 2012

This thesis is the result of conducting an analysis to find the solution to the phenomenon of power stoppage due to the disconnection of a CT (Current Transformer) because of vibration. The CT which measures the most essential current is used in power industries as part of a generator protection relay. When it comes to the bottom plate of a CT, nonconductor; such as bakelite and laminates; these material elements should be used because it is impossible to utilize the conductor when measuring the current of a generator which carries a high current if you use other materials. These nonconductor's material properties are irregular and interpretation errors often occur because the weight is light. In addition, since the change of dynamic characteristics which are related to the temperature often occur, it is important to match the real situation by considering an error of interpretation rather than selecting the quality of the material. Lastly, the conclusion that the study drew is that it is possible to avoid the resonance by utilizing three changes to the components to solve the problem concerning the high vibration which is caused by non-conductive objects. These changes are the most crucial points in this thesis: First, material changes to the Plate. Second, weight changes to the Coil. Third, thickness changes to the Plate.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.133-141
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• 2000

Enhanced the value of badge good with the gold plating of emblem, sports pictogram, mascot in 2002 Asian Game and World Cup, applying the plating and coating technique to screen printing. In addition, tourist and characteristic goods were of great value and image of visual communication displayed outside. After the screen printing in the surface of stainless steel, it obtained the plate coloring of beautiful a black glossy with a black Ru plating. At the identical surface, it did that the electrodeposition coating process in order to making a conductor state of image areas and a nonconductor state of nonimage areas. After the electrodeposition process, it removed the printing ink of image areas with solvent. A manufacturing process, it removed the printing ink of image areas with solvent. A manufacturing process completed with copper, nickel and gold plating at bared metal surface.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1496-1499
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• 2005

This paper was represented an electrostatics distribution analysis using FEM(finite element method) with industrial type Inkjet plotter. Here, we know electronic value with each system position by experiment. these were decreased by discharge through earth and electricity shielding. According to industrial development, all fields using chemical instrument and material are generated an electrostatics. Based on these, the big large position of electrostatics was obtained metal base of controller, nonconductor fiber between two rubber roller, head controller by moving roller etc., Therefore these were showed an electrostatics generation source and by rubbing and meager profits electric charge.

• Fire Science and Engineering
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• v.25 no.3
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• pp.107-112
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• 2011

We have considered the fire hazard by the static in anti-static film manufacturing factory on this study. Solvents that the flash point as ethanol, methanol and iso-propyl alcohol is low are used on the manufacturing process of anti-static film, and the minimum ignition energy of these solvents is ignited easily despite less discharge energy form 0.16 mJ to 0.65 mJ. After the static electric potential produced on each of the manufacturing plants was measured, electric potential on films of paste board is measured form 17 kV to 20 kV. But this exceeds 5 kV, which is electrifiable of objective of nonconductor for fire & explode protection. Therefore, We figure out the fire hazard was high by a static discharge in anti-static film manufacturing factory.

• Journal of Korean Elementary Science Education
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• v.33 no.3
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• pp.597-606
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• 2014

The purpose of this study is to survey and analyze difficulties in teaching and learning elementary school science on the chapter titled 'electric circuit'. 28 elementary school teachers who teach 5th grade science and 73 5th grade students in elementary school were taken part in this survey. The pilot questionnaire was distributed to find out both the degree and the reason of difficulties in teaching and learning. The answers are analyzed with four areas to extract elements which make class difficult; Learner factors (L), Instruction factors (I), Curriculum & textbooks factors (C), and Environment factors (E). The results are as follows. (1) It can be seen that both students and teachers feel the highest difficulty in 7th lesson 'the direction of current', while they felt little difficulty in lesson 3 'conductor and nonconductor' and lesson 8 'the safety of electricity'. (2) The most mentioned reason of difficulties in teaching and learning was Learner factors (L). (3) Teachers felt many difficulties in experimental environment. On the other hands, students didn't think experimental failures as serious trouble. (4) Students felt many difficulties in new terms and hazy concepts or expressions. (5) Teachers felt a lot of difficulties in those from Curriculum & textbooks factors.

• Clean Technology
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• v.24 no.1
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• pp.77-84
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• 2018

In this study, $Li_4Ti_5O_{12}$ anode materials for lithium ion battery were synthesized by dry ball-mill method. Polyvinyl chloride (PVC) as a carbon source was added to improve electrochemical properties. When the PVC was added after $Li_4Ti_5O_{12}$ formation, the spinel structure was well synthesized and it was confirmed by X-ray diffraction (XRD) experiments. When the carbon material was added before the synthesis and the heat treatment was performed, it was confirmed that a material having a different crystal structure was synthesized even when a small amount of carbon material was added. In the case of $Li_4Ti_5O_{12}$ without the carbon material, the electrical conductivity value was about $10{\mu}S\;m^{-1}$, which was very small and similar to that of the nonconductor. As the carbon was added, the electrical conductivity was greatly improved and increased up to 10,000 times. Electrochemical impedance spectroscopy (EIS) analysis showed that the size of semicircle corresponding to the resistance decreased with the carbon addition. This indicates that the resistance inside the electrode is reduced. According to the Cyclic voltammetry (CV) analysis, the potential difference between the oxidation peak and the reduction peak was reduced with carbon addition. This means that the rate of lithium ion insertion and deinsertion was increased. $Li_4Ti_5O_{12}$ with 9.5 wt% PVC added sample showed the best properties in rate capabilities of $180mA\;h\;g^{-1}$ at 0.2 C-rate, $165mA\;h\;g^{-1}$ at 0.5 C-rate, and $95.8mA\;h\;g^{-1}$ at 5 C-rate.