• Advances in nano research
• /
• v.12 no.3
• /
• pp.291-300
• /
• 2022

The behavior of hydrogen species on the surface of the catalyst during the Lewis acid transformation to form Brønsted acid sites over the spherical silica-supported WO_x catalyst was investigated. To understand the structure-activity relationship of Lewis acid transformation and hydrogen bonding interactions, we explore the potential of using the in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) with adsorbed ammonia and hydrogen exposure. From the results of in situ DRIFTS measurements, Lewis acid sites on surface catalysts were transformed into new Brønsted acid sites upon hydrogen exposure. The adsorbed NH₃ on Lewis acid sites migrated to Brønsted acid sites forming NH⁴⁺. The results show that the dissociated H atoms present on the catalyst surface formed new Si-OH hydroxyl species - the new Brønsted acid site. Besides, the isolated Si-O-W species is the key towards H-bond and Si-OH formation. Additionally, the H atoms adsorbed surrounding the Si-O-W species of mono-oxo O=WO₄ and di-oxo (O=)₂WO₂ species, where the Si-O-W species are the main species presented on the Inc-SSP catalysts than that of the IWI-SSP catalysts.

• Applied Chemistry for Engineering
• /
• v.21 no.4
• /
• pp.377-384
• /
• 2010

We perform a comparative study to investigate the properties of the new energetic chain extender (AzPD). A series of poly(glycidyl azide)/poly(tetramethylene oxide)-based energetic segmented polyurethane (GAP/PTMG ESPU) with different chain extender, which is 3-azidopropane-1,2-diol (AzPD), 1,4-butane diol (1,4-BD), or 1,5 pentane diol (1,5-PD), was synthesized by solution polymerization in dimethyl formamide (DMF) and their phase behaviors were investigated. The ESPUs were characterized with Fourier transform infrared-attenuated total reflection spectroscopy (ATR FT-IR), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The results of the ATR FT-IR analysis of the urethane carbonyl group region showed that the 'free' C=O fraction was higher in GAP/PTMG AzESPU (0.5) than GAP/PTMG BDESPU (0.44) and GAP/PTMG PDESPU (0.41) for 7 days samples after preparation and that it was similar in the range of 0.26~0.29 for three 60 days ESPU samples. DMA curves of the GAP/PTMG AzESPU for 7 days samples showed amorphous polymers, but GAP/PTMG BDESPU and GAP/PTMG PDESPU showed viscoelastic behaviors with rubbery plateau and the flow region. However, DMA curves of the GAP/PTMG AzESPU for 60 days samples showed viscoelastic behaviors with rubbery plateau and the flow region like GAP/PTMG PDESPU, but GAP/PTMG BDESPU did not show the flow region. From phase behaviors with ATR FT-IR, DSC and DMA analysis, GAP/PTMG AzESPU showed good phase-mixing between components. However, it represented viscoelastic behavior of TPE similar to GAP/PTMG PDESPM according to phase equilibrium progress with aging time.

• Journal of the Korean Vacuum Society
• /
• v.22 no.1
• /
• pp.13-19
• /
• 2013

It is expected that progress in building-integrated photovoltaic (BIPV) systems, improving the functionality and design of buildings, will be accelerated in the coming years. While the dye sensitized solar cell is considered one of the most important technologies in the BIPV field, the transparent silicon based thin film solar cell fabricated by thin film processes has drawn attention as a novel alternative. When the selective transmitting layer is applied to the solar cell, the conversion efficiency is improved due to the re-reflection of infrared light into an absorber layer with the transmission of visible light through the solar cell. In this work, we prepared Al-Ti based oxide thin films using cost-effective sputter deposition and examined their selective transmitting characteristics with various compositions. The transmittance and reflectance of the Al-Ti based oxide thin film changed with the variation of its composition, and the selective transmitting property was observed in the sample with the 25 nm-thick AlTiO layer. It is considered that the realization of transparent solar cells and the improvement of their conversion efficiency can be achieved by introducing the Al-Ti based selective transmitting layer.

• Corrosion Science and Technology
• /
• v.7 no.1
• /
• pp.50-60
• /
• 2008

The majority of the described experimental results deal with relatively pure aluminium. Variations were made in the pretreatment of the aluminum substrates and an investigation was performed on the resulting changes in oxide layer composition and chemistry. Subsequently, the bonding behavior of the surfaces was investigated by using model adhesion molecules. These molecules were chosen to represent the bonding functionality of an organic polymer. They were applied onto the pretreated surfaces as a monolayer and the bonding behavior was studied using infrared reflection absorption spectroscopy. A direct and clear relation was found between the hydroxyl fraction on the oxide surfaces and the amount of molecules that subsequently bonded to the surface. Moreover, it was found that most bonds between the oxide surface and organic functional groups are not stable in the presence of water. The best performance was obtained using molecules, which are capable of chemisorption with the oxide surface. Finally, it was found that freshly prepared relatively pure aluminum substrates, which are left in air, rapidly lose their bonding capacity towards organic functional groups. This can be attributed to the adsorption of contamination and water to the oxide surface. In addition the adhesion of a typical epoxy-coated aluminum system was investigated during exposure to water at different temperatures. The coating was found to quite rapidly lose its adhesion upon exposure to water. This rapid loss of adhesion corresponds well with the data where it was demonstrated that the studied epoxy coating only bonds through physisorptive hydrogen bonding, these bonds not being stable in the presence of water. After the initial loss the adhesion of the coating was however found to recover again and even exceeded the adhesion prior to exposure. The improvement could be ascribed to the growth of a thin oxyhydroxide layer on the aluminum substrate, which forms a new, water-stable and stronger bond with the epoxy coating. Two routes for improvement of adhesion are finally decribed including an interphasial polymeric thin layer and a treatment in boiling water of the substrate before coating takes place. The adhesion properties were finely also studied as a function of the Mg content of the alloys. It was shown that an enrichment of Mg in the oxide could take place when Mg containing alloys are heat-treated. It is expected that for these alloys the (hydr)oxide fraction also depends on the pre-treatment and on the distribution of magnesium as compared to the aluminium hydroxides, with a direct impact on adhesive properties.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.39 no.5
• /
• pp.486-493
• /
• 2002

In this paper, we proposed the effective multispectral image compression method using CIBP(classified interband bidrectional prediction) and extended SPIHT(set partition in hierarchical trees) in wavelet domain. We determine separately feature bands that have the highest correlation with other bands in the visible range and in the infrared range of wavelengths. Feature bands are coded to remove the spatial redundancy with SPIHT in the wavelet domain. Prediction bands that have high correlation with feature bands are wavelet transformed and they are classified into one of three classes considering reflection characteristics of the baseband. For Prediction bands, CIBP is performed to reduce the spectral redundancy. for the difference bands between prediction bands and the predicted bands, They are ordered to upgrade the compression efficiency of extended SPIHT with the largest error magnitude. The arranged bands are coded to compensate the prediction error with extended SPIHT. Experiments are carried out on the multispectral images. The results show that the proposed method reconstructs higher quality images than images reconstructed by the conventional methods at the same bit rate.

• KIPS Transactions on Computer and Communication Systems
• /
• v.2 no.10
• /
• pp.427-436
• /
• 2013

In this paper, a method of moving path control of an automatic guided vehicle in an indoor environment through recognition of marker images using vision sensors is presented. The existing AGV moving control system using infrared-ray sensors and landmarks have faced at two critical problems. Since there are many windows in a crematorium, they are going to let in too much sunlight in the main hall which is the moving area of AGVs. Sunlight affects the correct recognition of landmarks due to refraction and/or reflection of sunlight. The second one is that a crematorium has a narrow indoor environment compared to typical industrial fields. Particularly when an AVG changes its direction to enter the designated furnace the information provided by guided sensors cannot be utilized to estimate its location because the rotating space is too narrow to get them. To resolve the occurrences of such circumstances that cannot access sensing data in a WSN environment, a relative distance from marker to an AGV will be used as fingerprinting used for location estimation. Compared to the existing fingerprinting method which uses RSS, our proposed method may result in a higher reliable estimation of location. Our experimental results show that the proposed method proves the correctness and applicability. In addition, our proposed approach will be applied to the AGV system in the crematorium so that it can transport a dead body safely from the loading place to its rightful destination.

• Journal of the Korean Chemical Society
• /
• v.37 no.6
• /
• pp.570-576
• /
• 1993

1-, 3-, 9-, and 21-Monolayer Langmuir-Blodgett(LB) films of stearic acid were deposited on silver-coated glass slides at the surface pressure of 30 mN/m. Fourier transform infrared(FTIR) reflection-absorption spectra (RAS) of these LB films were recorded at various temperatures from 31 to $72^{\circ}C.$ The spectra at $31^{\circ}C$ exhibited characteristic features of highly perpendicular orientation of the hydrocarbon chain. In the 1-monolayer LB film, the C=O stretching band was not observed, presumably due to the image dipole effect on the silver surface. In the 1-and 3-monolayer LB films, the trans isomer of stearic acid was prominent, but the cis isomer was dominant in the 21-monolayer LB film. FTIR-RAS measurements at an elevated temperature indicated that the chain melting temperature increases and approached to the bulk melting point with increasing the number of monolayer, except for the 1-monolayer LB film which has a higher melting temperature than the 3-monolayer film due to the strong interaction with the silver substrate.

• Journal of Adhesion and Interface
• /
• v.13 no.1
• /
• pp.31-37
• /
• 2012

In this study, we investigated the curing properties of UV-LED curable color coating. Specially, the effects of UV-LED wavelength (365, 395, and 405 nm), inert gas, the concentration of photosensitizer, and dual curing on the curing behavior of UV-LED coating systems were studied. The photopolymerization behaviors and the unreacted acrylate groups at Film-air (FA) interface and Film-substrate (FS) interface were investigated by photo differential scanning calorimetry (Photo-DSC) and Fourier-transform infrared spectroscopy with attenuated total reflection (FT-IR/ATR), respectively. Photo-DSC results showed that the heat flow and the ultimate conversion for coating system cured by 405 nm UV-LED were higher than the corresponding values for coating systems cured by 395 and 365 nm UV-LED. FT-IR/ATR results showed that the UV-LED curing systems improved interior and through curing of the coating film, but significantly are affected by oxygen inhibition at FA-interface. The inert environment such as nitrogen purging and the dual curing improved the surface and interior curing of the coating films.

• Korean Journal of Remote Sensing
• /
• v.20 no.5
• /
• pp.289-305
• /
• 2004

Atmospheric correction of Landsat Visible and Near Infrared imagery (VIS/NIR) over aquatic environment is more demanding than over land because the signal from the water column is small and it carries immense information about biogeochemical variables in the ocean. This paper introduces two methods, a modified dark-pixel substraction technique (path--extraction) and our spectral shape matching method (SSMM), for the correction of the atmospheric effects in the Landsat VIS/NIR imagery in relation to the retrieval of meaningful information about the ocean color, especially from Case-2 waters (Morel and Prieur, 1977) around Korean peninsula. The results of these methods are compared with the classical atmospheric correction approaches based on the 6S radiative transfer model and standard SeaWiFS atmospheric algorithm. The atmospheric correction scheme using 6S radiative transfer code assumes a standard atmosphere with constant aerosol loading and a uniform, Lambertian surface, while the path-extraction assumes that the total radiance (L/sub TOA/) of a pixel of the black ocean (referred by Antoine and Morel, 1999) in a given image is considered as the path signal, which remains constant over, at least, the sub scene of Landsat VIS/NIR imagery. The assumption of SSMM is nearly similar, but it extracts the path signal from the L/sub TOA/ by matching-up the in-situ data of water-leaving radiance, for typical clear and turbid waters, and extrapolate it to be the spatially homogeneous contribution of the scattered signal after complex interaction of light with atmospheric aerosols and Raleigh particles, and direct reflection of light on the sea surface. The overall shape and magnitude of radiance or reflectance spectra of the atmospherically corrected Landsat VIS/NIR imagery by SSMM appears to have good agreement with the in-situ spectra collected for clear and turbid waters, while path-extraction over turbid waters though often reproduces in-situ spectra, but yields significant errors for clear waters due to the invalid assumption of zero water-leaving radiance for the black ocean pixels. Because of the standard atmosphere with constant aerosols and models adopted in 6S radiative transfer code, a large error is possible between the retrieved and in-situ spectra. The efficiency of spectral shape matching has also been explored, using SeaWiFS imagery for turbid waters and compared with that of the standard SeaWiFS atmospheric correction algorithm, which falls in highly turbid waters, due to the assumption that values of water-leaving radiance in the two NIR bands are negligible to enable retrieval of aerosol reflectance in the correction of ocean color imagery. Validation suggests that accurate the retrieval of water-leaving radiance is not feasible with the invalid assumption of the classical algorithms, but is feasible with SSMM.

• Nuclear Engineering and Technology
• /
• v.54 no.11
• /
• pp.4102-4110
• /
• 2022

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m². Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 ℃, much below the permissible value of tungsten material (~1200 ℃). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-active-multijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5° toroidally from the 4.6 GHz LH system and is not magnetically connected.