• Polymer(Korea)
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• v.31 no.6
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• pp.538-542
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• 2007

This study is on the performance analysis of modified asphalts which were prepared by mixing the asphalt with polymer modifiers of varying compositions which were synthesized by the emulsion polymerization method. Thermal properties of mired asphalt were investigated by DSC (differential scanning calorimetry), and dispersion of modifiers in asphalt was investigated by the fluorescence microscope. Dynamic stability and permanent deformation velocities of mixed asphalt were investigated by wheel tracking measurements. Modifier 6 showed the best results in both penetration test and wheel tracking measurement among investigated modifiers, which supports MMA(methyl methacrylate) moiety in modifiers plays better contribution for the enhancement of asphalt performance than styrene moiety does.

• Tribology and Lubricants
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• v.26 no.6
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• pp.317-321
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• 2010

Thin films of tin sulphide (SnS) have been formed by a novel 2-stage process where-in D.C. magnetron sputtering was used to deposit to thin films of tin (Sn) and the layers then sulphidised using 5% hydrogen sulphide ($H_2S$) gas in Argon. Although it was not found possible to deposit high quality thin films of tin directly onto glass substrates, excellent layers of tin were produced by using molybdenum (Mo) coated glass as the substrate material. The chemical and physical properties of the SnS layers formed were determined using scanning electron microscopy, energy dispersive x-ray analysis, x-ray diffraction studies and using reflectance versus wavelength measurements and these related to the conditions of synthesis. The data shows that it should be possible to produce conventional "substrate structure" devices based on the use of this technology.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.27-32
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• 2011

Tin nanoparticles were synthesized at room temperature by a compulsive reduction reaction using tin(II) acetate and tin(II) chloride precursors. When an identical amount (0.015 g) of polyvinyl pyrrolidone (PVP) was added, it was concluded that the probability of abnormally big particles forming increased with an increase in PVP molecular weight, resulting in the wide distribution of Sn nanoparticles. Differential scanning calorimetry measurements were carried out using diethylene glycol solution containing synthesized tin nanoparticles. When the population of specific particles with sizes below 35 nm was adequate, the melting point depression peaks of tin nanoparticles corresponding to the specific size were observed besides an evaporation endothermic peak of DEG during the first heating. Because DEG was evaporated and tin nanoparticles in contact became molten and coarsened during the first heating, a melting peak of bulk tin was only observed at $232^{\circ}C$ during the second heating.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1613-1618
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• 2014

Perovskite-type oxides are promising oxygen carriers in producing oxygen-enriched $CO_2$ gas stream for oxyfuel combustion. In this study, a new series of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ (x = 0.2, 0.4, 0.6, 0.8) was prepared and used to produce $O_2/CO_2$ mixture gas. The phase, crystal structure, and morphological properties of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ were investigated through X-ray diffraction, specific surface area measurements, and environmental scanning electron microscopy. The oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ was studied in a fixed-bed reactor system. Results showed that the different x values of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ have no obvious effects on crystalline structure. However, the oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ is improved by Co doping. Moreover, $SrCo_{0.8}Fe_{0.2}O_{3-{\delta}}$ synthesized via a new EDTA method has a larger BET surface area ($40.396m^2/g$), smaller particle size (48.3 nm), and better oxygen production performance compared with that synthesized through a liquid citrate method.

• Journal of Environmental Science International
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• v.23 no.6
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• pp.1175-1182
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• 2014

In this study, we examined the effect of cathode from electrolysis reactor for treating ballast water. We are going to select a suitable cathode for seawater electrolysis after considering the effect on the generation of the oxidant of cathode and the electrode deposition materials adhering to the surface of cathode. Anode is Ru-Ti-Pd electrode and cathode are Ti, Pt, JP520 (Ni-Pt-Ce) electrodes. Using the cathode of the three types, experiments were conducted to examine the effects of TRO (total residual oxidants) generation concentration and RNO (N, N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation concentration (in 1, 35 psu), ohmic drop, FESEM(field emission scanning electron microscope) observation of cathode surface and EDX (energy dispersive X-ray spectroscopy) measurements of attached fouling material. The results showed that TRO generation concentration and RNO degradation concentration in according to each type of cathode are not different. The attached fouling materials were observed on the surface of Ti and the JP520 electrode by the observation of SEM after electrolysis for two hours, but it was not observed on the surface of Pt electrode. When considering the surface ohmic drop of cathode and the attached fouling materials, Pt electrode was judged as the excellent cathode.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.239-248
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• 2007

The accuracy and dimensional stability of rubber impression materials are very important for the fitness of the final restoration. The purpose of this investigation was to evaluate the effects of the storage time and pouring frequency of the additional silicone materials on dimensional stability. Total 30 impressions were made of tooth prepared single crown. The dies had 1 buccolingual, 1 mesiodistal and 1 occlusogingival lines. Two additional silicone materials(examixfine, aquasil) were included. 15 specimens were made of each impression material and poured by type IV stone over times(1hour, 24hours, 72hours) after mixing. 5 impressions poured after 1 hour were used for second pouring after 24hours and third pouring after 72hours. The same examiner measured each specimen 3 times after lazer scanning. All statistical tests were performed with the level of significance set at 0.05. The results indicated that significant difference at any measuring point of stone dies except the buccolingual and mesiodistal lines of the specimen made at 1hour after mixing with examixfine when measurements at 1hour, 24hours and 72hours were campared. There were significant difference between two impression materials and at every measuring point of stone dies made at second and third pouring. The length of measuring point increased significantly as time passed by and increase of the pouring frequency. However, this results are clinically acceptable except the dies of the third pouring. Under the conditions of this study, the shrinkage rate of the additional silicone rubber impression materials significantly increased as time passed by and increase of the pouring frequency.

• Archives of Craniofacial Surgery
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• v.21 no.4
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• pp.219-224
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• 2020

Background: Repair of the orbital floor following trauma or tumor removal remains a challenge because of its complex three-dimensional shape. The purpose of the present study is to understand normal orbital floor anatomy by investigating its differences across four groups (Caucasian American and East Asian, males and females) via facial bone computed tomography (CT). Methods: A total of 48 orbits in 24 patients between 20 and 60 years of age were evaluated. Although most patients underwent CT scanning following trauma, the orbital walls were intact in all patients. Linear and angular measurements of the orbital floor were obtained from CT images. Results: Orbital floor width, length, angle between the orbital floor and medial wall, and distance from the inferior orbital rim to the lowest point of the orbital floor did not show a statistically significant difference between groups. Angles made by the infraorbital rim, the lowest point of the floor, and the anterior border of the infraorbital fissure were statistically significantly wider in East Asian females than in male groups. The floor depth in East Asian females was significantly smaller compared to all the other groups. Conclusion: East Asian female population had smaller curvature and depth of an orbital floor than the other groups, which means racial and sex-related differences should be considered in the orbital floor reconstruction.

• Journal of Electrochemical Science and Technology
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• v.6 no.4
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• pp.139-145
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• 2015

Capacitive deionization (CDI) process is a novel approach for desalination of an aqueous salt solution. In the present study, an activated carbon cloth (ACC) is proposed as effective electrode material. Initially the carbon cloth was activated in 1 M and 8 M HNO₃ for 9 hours at room temperature. The untreated and chemically activated carbon cloth (ACC) electrode materials were subjected to BET surface area measurements in order to get information about their specific surface area, average pore size, total pore volume and micropore area. The above materials were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) also. The electrochemical studies for the electrodes were done using cyclic voltammetry (CV) in 0.1 M Na₂SO₄ medium. From the studies, it was found that resistivity of the activated carbon cloth electrodes (treated in 1 M and 8 M HNO₃) was decreased significantly by the chemical oxidation in nitric acid at room temperature and its capacitance was found to be 90 F/g (1 M HNO₃) and 154 F/g (8 M HNO₃) respectively in 0.1 M Na₂SO₄ solution. The capacitive deionization behavior of a single cell CDI with activated carbon cloth electrodes was also studied and reported in this work.

• Journal of Electrochemical Science and Technology
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• v.11 no.3
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• pp.282-290
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• 2020

In this article, we report the effect of blended cathode materials on the performance of all-solid-state lithium-ion batteries (ASLBs) with oxide-based organic/inorganic hybrid electrolytes. LiFePO₄ material is good candidates as cathode material in PEO-based solid electrolytes because of their low operating potential of 3.4 V; however, LiFePO₄ suffers from low electric conductivity and low Li ion diffusion rate across the LiFePO₄/FePO₄ interface. Particularly, monoclinic Li₃V₂(PO₄)₃ (LVP) is a well-known high-power-density cathode material due to its rapid ionic diffusion properties. Therefore, the structure, cycling stability, and rate performance of the blended LiFePO₄/Li₃V₂(PO₄)₃ cathode material in ASLBs with oxidebased inorganic/organic-hybrid electrolytes are investigated by using powder X-ray diffraction analysis, field-emission scanning electron microscopy, Brunauer-Emmett-Teller sorption experiments, electrochemical impedance spectroscopy, and galvanostatic measurements.

• The korean journal of orthodontics
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• v.47 no.4
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• pp.238-247
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• 2017

Objective: The aim of this study was to compare recycled and unused orthodontic miniscrews to determine the feasibility of reuse. The comparisons included both miniscrews with machined surfaces (MS), and those with etched surfaces (ES). Methods: Retrieved MS and ES were further divided into three subgroups according to the assigned recycling procedure: group A, air-water spray; group B, mechanical cleaning; and group C, mechanical and chemical cleaning. Unused screws were used as controls. Scanning electron microscopy, energy-dispersive X-ray spectrometry, insertion time and maximum insertion torque measurements in artificial bone, and biological responses in the form of periotest values (PTV), bone-implant contact ratio (BIC), and bone volume ratio (BV) were assessed. Results: Morphological changes after recycling mainly occurred at the screw tip, and the cortical bone penetration success rate of recycled screws was lower than that of unused screws. Retrieved ES needed more thorough cleaning than retrieved MS to produce a surface composition similar to that of unused screws. There were no significant differences in PTV or BIC between recycled and unused screws, while the BV of the former was significantly lower than that of the latter (p < 0.05). Conclusions: These results indicate that reuse of recycled orthodontic miniscrews may not be feasible from the biomechanical aspect.