• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.185-192
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• 1998

Four kinds of polyamicacids(PAAs) were prepared by the condensation reaction of four diamines with different linkages, 3,3'-diaminodiphenyl sulfone(3,3'-$DDSO_2$), 4,4'-diaminodiphenyl sulfone(4,4'-$DDSO_2$), 4,4'-methylene dianiline(4,4'-MDA) and 4,4'-oxydianiline(4,4'-ODA), and dianhydride, 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA) using the solvent, dimethylacetamide(DMAc). These four PAAs were blended with poly[2,2-(m-phenylene)-5,5'-bibenzimidazole](PBI) from the solution blending. Then called as Blend-I, II, III, and IV, respectively. Cast films or precipitated powders of the PBI/PAA blends were cured at a higher temperature than expected Tg to transform into PBI/PIs blends. Miscibility, specific intermolecular interaction for miscibility and their relative strength as a function of polyimide chemical structure with different four diamines in the PBI/PI systems were investigated. Four blends used in this study were all miscible, and the specific intermolecular interactions existing in these blends was thought to be the hydrogen bonding between the N-H of PBI and the C=O of PIs. The hydrogen bonding in the blends were shown to be stronger in the Blend-III and Blend-IV than Blend-I and II. It is speculated that the differences of hydrogen bonding strength of PBI/PI blends are dependent upon chemical structures of PIs, that is, PIs consisting of $SO_2$ group have a weaker hydrogen bonding strength than those of O or $CH_2$ group because the former has a larger spacer than the latter.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.965-974
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• 2009

This study evaluated the degradation efficiency of malodorous sulfurized-organic compounds by utilizing N- and Sdoped titanium dioxide under visible-light irradiation, and examined the catalyst deactivation and regeneration. Catalyst surface was characterized by employing Fourier-Transform-Infrared-Red (FTIR) spectra. The visible-light-driven photocatalysis techniques were able to efficiently degrade low-level dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) with degradation efficiencies exceeding 97%, whereas they were not effective regarding the removal of high-level DMS and DMDS, with degradation efficiencies of 84 and 23% within 5 hrs of photocatalytic processes. As compared with DMS, DMDS which containes one more sulfur element revealed quick catalyst deactivation. Catalyst deactivation was confirmed by the equality between input and output concentrations of DMD or DMDS, the obsevation of no $CO_2$ generation during a photocatalytic process, and the FTIR spectrum peaks related with sulfur ion compounds, which are major byproducts formed on catalyst surfaces. The mineralization efficiency of DMS at 8 ppm, which was a peak value during a photocatalytic process, was calculated as 144%, exceeding 100%. The catalyst regenerated by high-temperature calcination exhibited higher catalyst recovery efficiency (53 and 58% for DMDS and DMS, respectively) as compared with dry-air and humid-air regeneration processes. However, even the calcined method was unable to totally regenerate deactivated catalysts.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.1
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• pp.1-15
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• 2000

To reconstruct 3- D shape, It is a common strategy to acquire multiple range Images from different viewpoints and integrate them into a common coordinates In this paper, we particularly focus on the registration and integration processes for combining all range Images into one surface model. For the registration, we propose the 2-step registration algorithm, which consists of 2 steps the rough registration step using all data points and the fine registration step using the high-curved data points For the integration, we propose a new algorithm, referred to as ‘multi-registration’ technique, to alleviate the error accumulation problem, which occurs during applying the pair-wise registration to each range image sequentially, in order to transform them into a common reference frame Intensive experiments are performed on the various real range data In experiments, all range images were registered within 1 minutes on Pentium 150MHz PC The results show that the proposed algorithms registrate and integrate multiple range Images within a tolerable error bound in a reasonable computation time, and the total error between all range Images are equalized with our proposed algorithms.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.275-281
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• 2020

Purpose: Development of a latent antimicrobial soft liner is strongly needed to overcome a possible inflammation related with its dimensional degrade or surface roughness. Modified tissue conditioner (TC) containing chitosan-doped silver nanoparticles (ChSN) complexes were synthesized and assessed for their characterizations. Materials and methods: ChSN were preliminarily synthesized from silver nitrate (AgNO₃), sodium borohydride (NaBH₄) as a reducing agent and chitosan biopolymer as a capping agent. Ultraviolet-visible and Fourier transform infrared spectroscopy were conducted to confirm the stable reduction of nanoparticles with chitosan. Modified TC blended with ChSN by 0 (control), 1.0, 3.0 and 5.0 % mass fraction were mechanically tested by ultimate tensile strength (UTS), silver ion elution and color stability (n=7). Results: At 24 hour and 7 day storage periods, UTS values were not significant (P>.05) as compared with pristine TC (control) and silver ion was detected with the dose-dependent values of ChSN incorporated. Color stability of TC were influenced by ChSN add, with the higher doses, the significantly greater color changes (P<.05). Conclusion: A stable synthesized ChSN was acquired and modified TC loading ChSN was characterized as silver ion releasing without detrimental physical property. For its clinical application, antimicrobial test, color control and multifactor investigations are still required.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.5
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• pp.587-594
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• 2000

At present embryonic stem (ES) cells with confirmed pluripotential properties are only available in the mouse. Recently, we were able to isolate, culture and genetically transform primordial germ cell (PGC)-derived cells from pig embryos and demonstrate their ability to contribute to chimera development in the pig. In order to determine whether the system we developed could be used to isolate embryonic germ (EG) cells from other mammalian species, we placed isolated PGCs from cattle, goats, rabbits and rats in culture. Briefly, PGCs were isolated from fetuses of cow (day 30-50), goat (day 25), rabbit (day 15-18) and rat (day 11-12), and plated on STO feeder cells in Dulbecco's modified Eagle's medium (DMEM): Ham's F10 medium (1:1) supplemented with 0.01 mM nonessential amino acids, 2 mM L-glutamine, 0.1 mM $\beta$ - mercaptoethnol, soluble recombinant human stem cell factor (SCF; 40ng/ml), human basic fibroblast growth factor (bFGF; 20ng/ml) and human leukemia inhibitory factor (LIF; 20ng/ml). For maintenance of the cells, colonies were passed to fresh feeders every 7-10 days. In all species tested, we were able to obtain and maintain colonies with ES-like morphology. Their developmental potential was tested by alkaline phosphatase (AP) staining and in vitro differentiation assay. For genetic transformation, cells were electroporated with a construct containing the green fluorescent protein (GFP) under the control of the cytomegalovirus (CMV) promoter. GFP-expressing colonies were detected in cattle, rabbits and rats. These results suggest that PGC-derived cells from cattle, goats, rabbits and rats can be isolated, cultured, and genetically transformed, and provide the basis for analyzing their developmental potential and their possible use for the precise genetic modification of these species.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.305-313
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• 2013

In this study, we investigated effects of thermal annealing on the thermal properties and microphase separation behaviors of glycidyl azide-based thermoplastic polyurethane elastomers (ETPE). The GAP-based ETPEs were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), and gel permeation chromatography (GPC). The effects of annealing temperature conditions ($80{\sim}130^{\circ}C$, 1 h or 24 h) on the properties of the ETPEs were investigated. The intensity of azide group absorption peak of ATR-FTIR spectra and the solubility of ETPE for methylene chloride and dimethylformamide solvent decreased after the annealing at $130^{\circ}C$ for 1 h and at $105^{\circ}C$ for 24 h. With increasing the annealing temperature from $80^{\circ}C$ to $110^{\circ}C$, the high temperature rubbery plateau region of storage modulus curves from DMA thermogram for GAP-based ETPEs was extended to the higher temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.301-309
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• 2016

To facilitate the effective use of butter clam shell as a natural calcium resource, we determined the optimal conditions for calcium lactate (BCCL) preparation with high solubility using response surface methodology (RSM). The polynomial models developed by RSM for pH, solubility and yield were highly effective in describing the relationships between factors (P<0.05). Increased molar ratios of calcined powder (BCCP) from butter clam shell led to reduced solubility, yield, color values and overall quality. The critical values of multiple response optimization to independent variables were 1.75 M and 0.94 M for lactic acid and BCCP, respectively. The actual values (pH 7.23, 97.42% for solubility and 423.22% for yield) under optimization conditions were similar to the predicted values. White indices of BCCLs were in the range of 86.70–90.86. Therefore, organic acid treatment improved color value. The buffering capacity of BCCLs was strong, at pH 2.82 to 3.80, upon the addition of less than 2 mL of 1 N HCl. The calcium content and solubility of BCCLs were 6.2–16.7 g/100 g and 93.6-98.5%, respectively. Fourier transform analysis of infrared spectroscopy data identified BCCL as calcium lactate pentahydrate, and the analysis of microstructure by field emission scanning electron microscopy revealed an irregular form.

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.102-111
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• 2010

This study was conducted to investigate the optimal conditions of collagen extraction from scales of yellowfin tuna (Thunnus albacares) using surface response methodology. Four independent variables of NaOH concentration and pretreatment fime in alkali pretreatment and enzyme concentration and treatment time in enzyme hydrolysis were used to predict a model equation for the collagen yield. The determinant coefficient ($R^2$) for the equation was 0.906. The values of the independent variables for the maximum yield were 0.32 N NaOH, 16.38 h alkali pretreatment time, 0.18% enzyme concentration, and 31.02 h enzyme treatment time. In the physicochemical properties of tuna scale collagen, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of tuna scale collagen showed the same migration distances as that of calf skin collagen. The amide A, I, II, and III regions of tuna scale collagen in Fourier transform infrared measurements were shown in the peaks of 3,414 $cm^{-1}$, 1,645 $cm^{-1}$, 1,553 $cm^{-1}$, and 1,247 $cm^{-1}$, respectively. The amount of imino acids in tuna scale collagen was 18.97% and the collagen denaturation temperature was $33^{\circ}C$. The collagen solubility as a function of NaCl concentration decreased to 4% NaCl (w/v) and the collagen solubility as a function of pH was high at pH 2-4 and sharply decreased from pH 4 to pH 7. Viscosity of the collagen solution decreased continuously until $30^{\circ}C$ and this decreasing rate slowed in the temperature range of $35-50^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.120-120
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• 1998

Boron nitride (BN) films have attracted a growing interest for a variety of t technological applications due to their excellent characteristics, namely hardness, c chemical inertness, and dielectrical behavior, etc. There are two crystalline phases 1551; of BN that are analogous to phases of carbon. Hexagonal boron nitride (h-BN) has a a layered s$\sigma$ucture which is spz-bonded structure similar to that of graphite, and is t the stable ordered phase at ambient conditions. Cubic boron nitride (c-BN) has a z zinc blende structure with sp3-bonding like as diamond, 따ld is the metastable phase a at ambient conditions. Among of their prototypes, especially 삼Ie c-BN is an i interesting material because it has almost the same hardness and thermal c conductivity as di없nond. C Conventionally, significant progress has been made in the experimental t techniques for synthesizing BN films using various of the physical vapor deposition 밍ld chemical vapor deposition. But, the major disadvantage of c-BN films is that t they are much more difficult to synthesize than h-BN films due to its narrow s stability phase region, high compression stress, and problem of nitrogen source c control. Recent studies of the metalorganic chemical vapor deposition (MOCVD) of I III - V compound have established that a molecular level understanding of the d deposition process is mandatory in controlling the selectivity parameters. This led t to the concept of using a single source organometallic precursor, having the c constituent elements in stoichiometric ratio, for MOCVD growth of 삼Ie required b binary compound. I In this study, therefore, we have been carried out the growth of h-BN thin f films on silicon substrates using a single source precursors. Polycrystalline h-BN t thin films were deposited on silicon in the temperature range of $\alpha$)() - 900 $^{\circ}$C from t the organometallic precursors of Boron-Triethylamine complex, (CZHs)3N:BRJ, and T Tris(dimethylamino)Borane, [CH3}zNhB, by supersonic molecular jet and remote p plasma assisted MOCVD. Hydrogen was used as carrier gas, and additional nitrogen w was supplied by either aDlIDonia through a nozzle, or nitrogen via a remote plasma. T The as-grown films were characterized by Fourier transform infrared spectroscopy, x x-ray pthotoelectron spectroscopy, Auger electron spectroscopy, x-ray diffraction, t transmission electron diffraction, optical transmission, and atomic force microscopy.roscopy.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.535-541
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• 2005

We report on the development of a passively mode-locked near-infrared femtosecond laser with Cr:YAG crystal that operates near room temperature. The laser wavelength could easily be tuned by using only the internal prism pair over 110 nm from 1400 nm to 1510 nm in cw and over about 30 nm in mode-locked operation, respectively Maximum cw output powers of 810 mW were obtained with $1.5 \%$ output coupler for absorbed pump powers of 7.6 W. For compensation of the internal group velocity dispersion, an IR graded prism pair was used. The Cr:YAG laser delivered nearly Fourier-transform limited pulses with a pulse duration as short as 64 fs at 100 MHz repetition rate. In the mode-locked regime, the laser was operating at 1510 nm with a spectral bandwidth of 44 nm. In order to avoid unstable mode-locking and power instabilities, self-built tubes were inserted into the beam path in the resonator and purged with N2 gas. Finally, output powers of the Cr:YAG laser were optimized to 250 mW fer long time stable mode-locked operation.