• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.268-273
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• 2015

While analyzing the specimens before and after the thermal shock test, we found that the power drop rate of the bare cell was 5.08%, while the power drop rate of the ribboned cell was 16.49%. In comparative terms, the efficiency was lower at the ribboned cell than at the bare cell. While analyzing through EL (Electroluminescence) shots and cross sections, we tried to decipher the exact cause of the power drop. Although mere color change of the cell was observed at the surface of the bare cell, no abnormality could be found inside the cell. On the surface of the ribboned cell, the short circuit of gridfinger extended from the front part of the front electrode of the ribboned cells. Therefore, cracks occurred on the surface of the cell. Cracks also appeared inside the cell. While analyzing the I-V curve, we determined an increase in the leakage current and an increase of resistances in series in the bare cell. In the ribboned cell, the resistances in parallel reduced remarkably. An increase of resistances in series could also be verified. Conclusively, we deduced that the power drop rate in the bare cell is a life span of the cell itself; aging is the cause of power drop rate in cells. In case of ribboned cell, the power drop rate was directly influenced by internal cracks and an intermetallic compound layer joining the ribbon at the front electrode.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.938-946
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• 2008

This study is on sealing leakage holes where are in landfills to make clay cakes with clay particles, which have a negative surface charge using the method of electrophoresis. Generally, electrophoresis is the motion of charged particles in a colloid under the influence of an electric field; particles with a positive charge go to the cathode and negative to the anode. In this study in order to develop the prevention system of leakages of the leachate in landfills, one-dimensional electrophoresis tests were conducted for determining the properties of the motion of the electrophoresis and cutoff using the method of electrophoresis depending on various the effect factors such as types of clays, concentrations of the clays, and applied electric field. In case of the experiments of determining the optimum clays, Na and Ca-Bentonite, Na and Ca-Montmorillonite, which have greater zeta-potential, cation, exchange capacity as well as ability of cutoff, and Micro-cement inducing cementation were chosen and then the effect of those clays was investigated. Moreover, the properties of the motion and settling of the clays were investigated following electric field varied from 0 to 1V/cm at different concentration of the clays in order to determine both the properties of the motion of the clays and the efficiency of electric field when applying different direct current. Ultimately, the ability of cutoff was examined through measuring the permeability of the clay cakes derived from the one-dimensional electrophoresis tests.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1157-1167
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• 2013

The development of electronic devices has recently led to many problems such as personal information rape and leakage of business information. Conventional loud-speakers have been generally used to output devices. It can be, however, operated as a micro-phone which was abused as a means for eavesdropping since the speaker and microphone have basically the equivalent structure. Most importantly, the general peoples are not aware of the approaching danger about using speaker as microphone. And, traditional eavesdropping detection equipment does not check the attack. In this paper, we demonstrate that there is a serious danger and vulnerability in using loud-speakers since they can be used as eavesdropping devices.

• Tribology and Lubricants
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• v.30 no.5
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• pp.303-310
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• 2014

In order to reduce friction and improve reliability, researchers have applied various surface texturing methods to highly sliding machine elements such as mechanical seals and piston rings. Despite extensive theoretical research on surface texturing, previous numerical results are only applicable to isothermal and iso-viscous conditions. Because the lubricant flow pattern of textured bearing surfaces is much more complicated than that for non-textured bearings, the Navier?Stokes equation is more suitable than the Reynolds equation for the former. This study carries out a thermohydrodynamic (THD) lubrication analysis to investigate the lubrication characteristics of a single micro-dimpled parallel thrust bearing cell. The analysis involves using the continuity, Navier?Stokes, energy, temperature?viscosity relation, and heat conduction equations with the commercial computational fluid dynamics (CFD) code FLUENT. This study discretizes these equations using the finite volume method and solves them using the SIMPLE algorithm. The results include finding the streamlines, pressure and temperature distributions, and variations in the friction force and leakage for various dimple radii and depths. Increasing the dimple radius and decreasing the depth causes a recirculation flow to form because of a strong vortex, and the oil temperature greatly increases compared with the non-textured case. The present numerical scheme and results are applicable to THD analysis of various surface-textured sliding bearings and can lead to further study.

• Transactions on Electrical and Electronic Materials
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• v.8 no.2
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• pp.84-88
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• 2007

[ $Bi_{1.5}Zn_{1.0}Nb_{1.5}O_7$ ] (BZN), $Bi_2Mg_{2/3}Nb_{4/3}O_7$ (BMN), and $Bi_2Cu_{2/3}Nb_{4/3}O_7$ (BCN) pyrochlore thin films were prepared on $Cu/Ti/SiO_2/Si$ substrates by pulsed laser deposition and the micro-structural and electrical properties were characterized for embedded capacitor applications. The BZN, BMN, and BCN films deposited at $25\;^{\circ}C$ and $150\;^{\circ}C$, respectively show smooth surface morphologies and dielectric constants of about $39\;{\sim}\;58$. The high dielectric loss of the films deposited at $150\;^{\circ}C$ compared with films deposited at $25\;^{\circ}C$ was attributed to the defects existing at interface between the films and copper electrode by an oxidation of copper bottom electrode. The leakage current densities and breakdown voltages in 200 nm thick-BMN and BZN films deposited at $150\;^{\circ}C$ are approximately $2.5\;{\times}\;10^{-8}\;A/cm^2$ at 3 V and above 10 V, respectively. Both BZN and BMN films are considered to be suitable materials for embedded capacitor applications.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.680-692
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• 1997

New bonding agent systems have been supplied which operators can simply apply to conditioned tooth surfaces. The purpose of this study was to evaluate the shear bond strengths and the microleakages of three bonding agents and composite resins to dentin. Seventy-five extracted human maxillary and mandibular molar teeth were used in this study. For the shear bond strength test, the entire occlusal dentin surfaces of thirty teeth were exposed with Diamond Wheel Saw and smoothed with Lapping and Polishing Machine (South Bay Technology Co., U.S.A). For the microleakage test, Class V cavities were prepared in the buccal surfaces of fourtyfive teeth. They were randomly assigned into 3 groups according to dentin bonding agents ($Scotchbond^{TM}$ Multi-Purpose plus, ONE-$STEP^{TM}$ and Prime & $Bond^{TM}$)and composite resins (Z-100, $Aelitefil^{TM}$ and TPH $Spectrum^{TM}$) to be used. Bonding agents and composite resins were bonded to exposed dentin surfaces of the tooth crown and to Class V cavities on the buccal surfaces respectively according to manufacturer's directions. The shear bond strengths were measured by universal testing machine($U^{TM}$ AGS-100, Japan). In addition, the degree of micro leakage at the occlusal and gingival margin was examined by 2 % methylene blue and stereomicroscope(Olymous SZH 10, Japan). The results were as follows: 1. The shear bond strength to dentin was the highest value in SBMP-Plus group($16.68{\pm}7.38$ MPa) and the lowest value in Prime & Bond group($11.61{\pm}5.82$ MPa), but there was no significant difference of shear bond strength among three groups. 2. The degree of microleakage at both occlusal and gingival margin was showed the lowest in SBMP-Plus group and the highest in ONE-STEP group. 3. At both occlusal and gingival margin, there was significant difference of microleakage between SBMP-Plus and ONE-STEP/ Prime & Bond groups(p<0.05), but no significant difference of microleakage between ONE-STEP and Prime & Bond group(p>0.05).

• Journal of the Korea Convergence Society
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• v.8 no.3
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• pp.191-197
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• 2017

This development is for non-destructive machine using X-Ray source about detecting outline faults of below middle size products. The differentiation is product of research and development unspecialized small and medium-sized products using X-Ray light sources can check real time if the surface of an external fault of radiation dose reference, within the leakage. The speed control is possible by software solution. In addition, we're working on possibly block doors for worker safety and equipment at the same time that inner drive can be identified in the image. These principles, as a key enabler of the current inspection system such as the container is small to medium-sized parts - a long way from utilization level is possible. This research will give rise to major effects for other various non-destructive market industries except car-industry. The most important fact is that this developed non-destructive machine is controlled below $0.2micro-S{\mu}v$.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.47-61
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• 1998

The purpose of this study was to compare the microleakage pattern of glass ionomer with resin restoration in microleakage pattern of primary and permanent teeth. Microscopical observation of interface between tooth structure and restoration was also performed. 80 and 8 sound molar teeth were used for the microleakage test and SEM study respectively. Data were analyzed statistically using ANOVA test and/or t-Test. The results of the present study were as follows: 1. According to the result of microleakage pattern between primary and permanent tooth, primary tooth generally showed more micro leakage than permanent tooth in all groups (p<.05). 2. In the resin-filled groups, occlusal margin was shown to have more microleakage than gingival margin(p<.05). Whereas the glass ionomer-filled groups showed no statistically significant differences between them(p>.05). 3. No statistically significant differences in microleakage could be found between two different resin groups(p>.05), while Fuji II LC group showed less microleakage than Ketac-Fil group(p>.05). 4. The various type hybrid layer was evident under SEM in resin-filled groups both in primary and permanent teeth with generally thicker layer in primary group. Among glass-ionomer group, Fuji II LC group showed more intact adhesion to tooth surface than Ketac-Fil group

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.346-355
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• 1999

To evaluate the micro leakage of compomer, 4 materials were divided into 4 groups of 15 cavities each.(Group 1: Z-100, Group 2: Dyarct AP, Group 3: Fuji II LC, Group 4: Compoglass) After the class II cavities were prepared using carbide bur No. 553, all specimen were restored by incremental filling technique. In group 3, Z-100 was filled with a base of a light curing glass-ionomer. After 7 days, all specimens were thermocycled between $5^{\circ}C$ and $55^{\circ}C$ for 500 cycles, followed by placement in 50% silver nitrate dye for 2 hours at $37^{\circ}C$. After rinsed in distilled water, these teeth were immersed in photodeveloping solution and exposed to fluorescent light for 6 hours. Teeth were then washed in distilled water to remove the photodeveloping solution, sectioned mesio-distally and evaluated. The results were as follows : 1. In the cervical portion, there was significant difference between Fuji II LC and other groups(Z-100, Dyract AP, Compoglass), Fuji II LC had the least value.(p<0.05) 2. In the cervical portion, there was not significant difference among Dyract AP, Z-100 and Compoglass. 3. In the occlusal portion, there was not significant difference among Dyract AP, Z-100 and Compoglass. From the results above, In enamel, microleakage of compomer such as Dyract AP and Compoglass resemble to that of composite resin. It is thought that it is due to characteristics of composite resin portion of compomer. But in dentin, microleakage of compomer is higher than that of resin modified glass ionomer cement, it is thought that in compomer, acid-base reaction is not developed with dentin.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.236-246
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• 1998

The purpose of this study was to compare the degree of micro- leakage of new glass ionomer root canal sealer, Ketac-Endo(ESPE Co., Seefeld, Germany) with that of AH-26(De Trey Co., Ltd., U.S.A.). Root canal treatment using K -file, H -file, Gate Glidden drill was conducted on 49 extracted single-rooted teeth. 45 teeth were randomly divided into 3 experimental groups(15 teeth per group) and 4 teeth were used as the control group. Group 1 was used AH -26 sealer with the lateral condensation method for canal filling, group 2 was used Ketac-Endo with the single cone method and group 3 was used Ketac-Endo with the lateral condensation method. The control group was obturated with the single cone method without sealer. The teeth were covered with two coats of nail varnish after 48 hours of obturation. The teeth were immersed in India ink for 1 week and cleaned with methyl salicylate and then the degree of dye penetration were measured with stereomicroscope. The data were analyzed statistically by one-way ANOVA. The results were as follows: 1. 7 teeth in group 1, 5 in group 2, and 3 in group 3, were showed evidence of microleakage implying appropriate canal filling. 2, The mean average of microleakage was $0.17{\pm}0.32mm$ in group 1, $0.30{\pm}0.37mm$ in group 2. $0.10{\pm}0.21mm$ in group 3, showing that canal filling using the lateral condensation canal filling method with Ketac-Endo showed the least microleakage and using the single cone method with Ketac-Endo showed the largest amount of microleakage, 3. There were no statistically significant difference in the variation of microleakage among groups. From the results above, Ketac-Endo which has the advantage of glass ionomer, whether using the single cone method or the lateral condensation method, showed similar results as AH-26, but for clinical application it is thought that were studies on the properties of Ketac-Endo should be followed.