• Journal of Electrochemical Science and Technology
• /
• v.1 no.1
• /
• pp.19-24
• /
• 2010

Alloying degree is an important structural factor of PtRu catalysts for direct methanol fuel cells (DMFC). In this work, carbon supported PtRu catalysts were synthesized by reduction method using anhydrous ethanol as a solvent and $NaBH_4$ as a reducing agent. Using anhydrous ethanol as a solvent resulted in high alloying degree and good dispersion. The morphological structure and crystallanity of synthesized catalysts were characterized by X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM). CO stripping and methanol oxidation reaction were measured. Due to high alloying degree catalyst prepared in anhydrous ethanol, exhibited low onset potential for methanol oxidation and negative peak shift of CO oxidation than commercial sample. Consequently, samples, applying ethanol as a solvent, exhibited not only enhanced CO oxidation, but also increased methanol oxidation reaction (MOR) activity compared with commercial PtRu/C (40 wt%, E-tek) and 40 wt% PtRu/C prepared in water solution.

• Macromolecular Research
• /
• v.11 no.5
• /
• pp.347-351
• /
• 2003

The hydrophobic ligand-containing hollow polypropylene (PP) membranes were synthesized by the mutual radiation induced graft copolymerization with glycidylmethacrylate (GMA) onto hollow PP membrane followed by the subsequent functionalization with L-phenylalanine. FT-IR, elemental analysis and UV spectroscopy were utilized to characterize copolymer composition, and degree of grafting, functionalization conversion and ${\gamma}$-globulins adsorption. The degree of grafting on the PP surface increased with the reaction time and total dose of E-beam. In the subsquent functionalization, the amount of L-phenylalanine increased with the increase in the degree of grafting and the degree of conversion was about 30%. The ${\gamma}$-globulins adsorption experiments showed that adsorption capacity had a maximum value at pH 8. The ${\gamma}$-globulins adsorption capacity in the basic pH region was higher than in the acidic pH region.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.46 no.1
• /
• pp.1-9
• /
• 2019

The aim of this study was to compare the degree of conversion and polymerization shrinkage of low and high viscosity bulk-fill giomer-based and resin-based composites. Two bulk-fill giomer (Beautifil Bulk Restorative (BBR), Beautifil Bulk Flowable (BBF)), two bulk-fill (Tetric N-Ceram Bulk-fill (TBF), SureFil SDR flow (SDR)) and two conventional resin composites (Tetric N-Ceram (TN), Tetric N-flow (TF)) were selected for this study. The degree of conversion was measured by using Fourier transform infrared spectroscopy. Polymerization shrinkage was measured with the linometer. For all depth, BBR had the lowest degree of conversion and SDR had the highest. At 4 mm, the degree of conversion of low and high viscosity bulk-fill giomer resin composites was lower than that of bulk-fill resin composites (p < 0.05). At the depth between 2 mm and 4 mm, there were significant difference with TBF, TN and TF (p < 0.05), while no significant difference in the degree of conversion was measured for BBR, BBF and SDR. Polymerization shrinkage of six resin composites decreased in the following order: TF > SDR > BBF > TBF > TN and BBR (p < 0.05). Polymerization shrinkage of bulk-fill giomer resin composites was lower than that of bulk-fill resin composites (p < 0.05). From this study, it is found that the bulk-fill giomer resin composites and TBF were not sufficiently cured in 4 mm depth. The degree of conversion of low and high viscosity bulk-fill giomer resin composites was significantly lower than bulk-fill resin composites in both 2 mm and 4 mm depths. Therefore, such features of bulk-fill giomer resin composites should be carefully considered in clinical application.

• Journal of Broadcast Engineering
• /
• v.24 no.7
• /
• pp.1209-1220
• /
• 2019

The demand for virtual reality (VR) is rapidly increasing. Providing the immersive experience requires much operation and many data to transmit. For example, a 360-degree video (360 video) with at least 4K resolution is needed to offer an immersive experience to users. Moreover, the MPEG-I group defined three degrees of freedom plus (3DoF+), and it requires the transmission of multiview 360 videos simultaneoulsy. This could be a burden for the VR streaming system. Accordingly, in this work, a bitrate-saving method using projection conversion is introduced, along with experimental results for streaming 3DoF+ 360 video. The results show that projection conversion of 360 video with 360lib shows a Bjontegaard delta bitrate gain of as much as 11.4%.

• Restorative Dentistry and Endodontics
• /
• v.36 no.4
• /
• pp.313-323
• /
• 2011

Objectives: This study investigated the optimal combination of 3-component photoinitiation system, consisting of CQ, p-octyloxy-phenyl-phenyl iodonium hexafluoroantimonate (OPPI), and 2-dimethylaminoethyl methacrylate (DMAEMA) to increase the degree of conversion of resin monomers, and analyze the effect of the ratio of the photoinitiator to the co-initiator. Materials and Methods: Each photoinitiators (CQ and OPP) and co-initiator (DMAEMA) were mixed in three levels with 0.2 wt.% (low concentration, L), 1.0 wt.% (medium concentration, M), and 2.0 wt.% (high concentration, H). A total of nine groups using the Taguchi method were tested according to the following proportion of components in the photoinitiator system: LLL, LMM, LHH, MLM, MMH, MHL, HLH, HML, HHM. Each monomer was polymerized using a quartz-tungsten-halogen curing unit (Demetron 400, USA) for 5, 20, 40, 60, 300 sec and the degree of conversion (DC) was determined at each exposure time using FTIR. Results: Significant differences were found for DC values in groups. MMH group and HHM group exhibited greater initial DC than the others. No significant difference was found with the ratio of the photoinitiators (CQ, OPPI) to the co-initiator (DMAEMA). The concentrations of CQ didn't affect the DC values, but those of OPPI did strongly. Conclusions: MMH and HHM groups seem to be best ones to get increased DC. MMH group is indicated for bright, translucent color and HHM group is good for dark, opaque colored-resin.

• Journal of Service Research and Studies
• /
• v.10 no.4
• /
• pp.71-88
• /
• 2020

CB(Convertible bond) is mezzanine security that have the characteristics of bonds and stocks. From the perspective of investors, the purpose of the research is to empirically investigate the degree of investment efficiency of CB and to suggest efficient investment plans. The research method investigated the maturity interest rate, conversion price, and conversion date for CB, and then linked it with daily stock price fluctuations after the conversion date to determine the degree of investment efficiency and stock conversion effect of CB. As a result of the study, it was analyzed that the ratio of the conversion price exceeded days was only about 1/4 of the conversion date, so the investment efficiency was low. The conversion day yield was -6.3% on average and the maturity day yield was -5.2% on average, showing a minus return on average, which was calculated differently from investor expectations. It was analyzed that the number of stocks with a minus conversion day is 2.4 times greater than the number of plus stocks and 3.7 times more than the number of plus stocks with a minus maturity return, so the expected return on stock conversion of CB is low. The research contribution was derived from the problem that the expected rate of return of CB is not high, and it is that the investor's point of view when purchasing CB was established.

• Journal of information and communication convergence engineering
• /
• v.1 no.3
• /
• pp.139-142
• /
• 2003

In this paper, we consider the factors that affect a conversion loss performance in designing a single balanced diode mixer integrated with IRF(Image Reject Filter), based on the embedded electrical wavelength placed between the IRF and mixer, diode matching and LO drive amplifier. To evaluate the conversion loss performance, we suggest two types of a single balanced mixer using 90 degree branch line coupler, microstrip line and schottky diode. One is only mixer and the other is integrated with IRF and LO drive amplifier. The measured results of a single balance diode mixer integrated IRF show the conversion loss of 8.5 dB and the flatness of 1 dB p-p from 21.2 GHz to 22.6 GHz with 10 dBm LO. The measured input PI dB and IIP3 are 7 dBm and 15 dBm respectively under the nominal LO power level of 10dBm. The LO/RF and LO/IF isolation are 22 dB and 50 dB, respectively.

• Restorative Dentistry and Endodontics
• /
• v.29 no.4
• /
• pp.386-398
• /
• 2004

Objectives: The purpose of this study was to observe the reaction kinetics and the degree of polymerization of composite resins when cured by different light sources and to evaluate the effectiveness of the blue Light Emitting Diode Light Curing Units (LED LCUs) compared with conventional halogen LCUs. Materials and Methods: First, thermal analysis was performed by a differential scanning calorimeter (DSC). The LED LCU (Elipar Freelight, $320{\;}mW/\textrm{cm}^2$) and the conventional halogen LCU (XL3000, $400{\;}mV/\textrm{cm}^2$) were used in this study for curing three composite resins (SureFil, Z-250 and AEliteFLO). Second. the degree of conversion was obtained in the composite resins cured according to the above curing mode with a FTIR. Third, the measurements of depth of cure were carried out in accordance with ISO 4049 standards. Statistical analysis was performed by two-way ANOVA test at 95% levels of confidence and Duncan's procedure for multiple comparisons. Results: The heat of cure was not statistically different among the LCUs (p > 0.05). The composites cured by the LED (Exp) LCUs were statistically more slowly polymerized than by the halogen LCU and the LED (Std) LCU (p < 0.05). The composite resin groups cured by the LED (Exp) LCUs had significantly greater degree of conversion value than by the halogen LCU and the LED (Std) LCU (p =0.0002). The composite resin groups cured by the LED (Std) LCUs showed significantly greater depth of cure value than by the halogen LCU and the LED (Exp) LCU (p < 0.05).

• The Korean Journal of Ceramics
• /
• v.6 no.4
• /
• pp.405-407
• /
• 2000

Polycrystalline films of Ni- and Co-ferrites films are prepared from aqueous solution at $90^{\circ}C$ by ferrite plating, which are subjected to Fe$^57$ conversion electron Mossbauer spectroscopy in backscatter mode. The average angle of Fe spins relative to the film plane is evaluated as 18 degree and 82 degree for the Ni- and Co-ferrite films, respectively, indicating a prominent magnetic anisotropy parallel and perpendicular to the film plane. It was also verified by the magnetization measurements.

• Proceedings of the KACD Conference
• /
• 2003.11a
• /
• pp.576-577
• /
• 2003

I. Objectives This study investigated the dentin shear bond strength and the degree of conversion (DC) of currently used dentin bonding agents (DBAs) that were irradiated with a light emitting diode (LED) light curing unit (LCU) and a halogen LCU. II. Materials and methods The halogen LCU and the LED LCU used in this study were a VIP(Bisco, Schaumburg, IL, USA) and an Elipar Freelight(3M ESPE, St Paul, MN, USA) respectively. For the VIP, $400mW{\cdot}cm-2$ intensity mode was used to adjust to the intensity of the LED LCU. The DBAs used in this study were Scotchbond Multipurpose (3M ESPE), Single Bond (3M ESPE), One-step(Bisco), Clearfil SE Bond(Kuraray), and Adper Prompt(3M ESPE).(omitted)