• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.383-390
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• 1998

The interaction of phenoxide anion with several cationic surfactant micelles (DTAB, TTAB, CTAB, CDEAB, and CTAC) was studied by UV/Vis spectrophotometric method. The solubilization constants of phenoxide anion into the cationic micellar phase and the critical micelle concentration of these surfactants in the presence of the phenoxide anion could be determined from the absorbance changes. The measured solubilization constants were changed according to the following order: $K_s(CTAC)>K_s(CDEAB)>K_s(CTAB)>K_s(TTAB)>K_s(DTAB).$ Effects of salts(NaCl and NaBr) and n-alcohols(butanol, pentanol, and hexanol) on the solubilization of phenoxide anion by the TTAB system have been also measured and analyzed. There was a great decrease of solubilization constant and CMC with these additives. The standard Gibbs free energy, enthalpy, and entropy changes for the solubilization of phenoxide anion by the TTAB system were calculated from the temperature dependence of $K_s$ values.

• Polymer(Korea)
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• v.27 no.1
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• pp.33-39
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• 2003

In this study, the bisphenol-based DGEBA/GEBS blend systems were studied in cure kinetics, thermal stabilities, and fracture toughness of the casting specimen. The content of DGEBA/DCEBS was varied in 100 : 0, 90 : 10, 80 : 20, 70 : 30, and 60 : 40 wt%. The cure activation energies ($E_a$) of the blend systems were determined by Ozawa's equation. The thermal stabilities, including initial decomposed temperature (IDT), temperatures of maximum rate of degradation ($T_{max}$), and integral procedural decomposition temperature (IPDT) of the cured specimen were investigated by thermogravimetric analysis (TGA). For the mechanical interfacial properties of the specimens, the critical stress intensity factor ($K_{IC}$) test was performed and their fractured surfaces were examined by using a scanning electron microscope (SEM). As a result, $E_a$, IPDT, and $K_{IC}$ show maximum values in the 20 wt% DGEBS content compared with the neat DGEBA resins. This was probably due to the fact that the elevated networks were farmed by the introduction of sulfonyl groups of the DCEBS resin.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.397-405
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• 2003

In this paper, we propose an efficient motion estimation algorithm which can reduce computational complexity by using characteristics of wavelet coefficient in each subband while keeping about the same image quality as in using MRME(multiresolution motion estimation). In general, because of the high similarity between consecutive frames, we first decide whether the motion exists or not by just comparing MAD(mean absolute difference) between blocks with threshold in the lowest subbands of consecutive two frames. If it turns out that there is no motion in the lowest subband, we can also decide no motion exists in the higher subband. This is due to the characteristics of wavelet transform. Conversely, if we find any motion in the lowest subband, we can reduce computational complexity by estimating high subband motion vectors selectively according to the amount of computational complexity by estimating high subband motion vectors selectively according to the amount of energy in that subband. Experimental results are shown that algorithm suggested in this paper maintains about the same PSNR as MRME. However, the processing time was reduced about 30-50% compared with the MRME.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.6
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• pp.445-454
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• 1998

In order to establish a technical concept for the detection of defects in weldments in thin steel plate, an experimental and theoretical investigation was carried out for artificial defects in a steel plate having a thickness of 2.4mm by using the guided wave technique. In particular the goal was to find the most effective testing parameters paying attention to the relationship between the excitation frequency by a tone burst system and various incident angles. It was found that the test conditions that worked best was for a frequency of 840kHz and an incident angle of 30 or 85 degrees, most of the defects were detected with these conditions. Also, it was clear that a guided wave mode generated under an incident angle of 30 degrees was a symmetric mode, So, and that of 85 degrees corresponded to an antisymmetric mode, Ao. By using the two modes, most of all of the defects could be detected. Furthermore, it was shown that the antisymmetric mode was more sensitive to defects near the surface than the symmetric mode. Theoretical predictions confirmed this sensitivity improvement with Ao for surface defects because of wave structure variation and energy concentration near the surface.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.853-860
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• 2019

In order to meet more severe environmental regulations, oxy-fuel circulating fluidized bed(CFB) boilers or ultra supercritical CFB boilers, which are a kind of process in that solid particles moves similar to fluid, have been developed in the world. In CFB power generation processes, the method to reduce or remove sulfur dioxide is in-situ desulfurization reaction via limestone directly injected into CFB boilers. However, the desulfurization efficiencies have continuously changed because limestones injected into CFB boilers are affected by various operation conditions (Bed temperature, pressure, solid circulating rate, solid holdup, residence time, and so on). In this study, a prediction method with physical and chemical properties of limestone and operation conditions of CFB boiler for in-situ desulfurization reaction in CFB boilers has developed by integrating desulfurization kinetic equations and hydrodynamics equations for CFB previously published. In particular, the prediction equation for in-situ desulfurization was modified by using experimental results from desulfurization reactions of various domestic limestones.

• Environmental and Resource Economics Review
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• v.28 no.1
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• pp.95-120
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• 2019

As the Nagoya Protocol has been in effect since 2014, firms that invest in projects related with the genetic resources should establish methods to share the benefits arising from using genetic resources with the country providing such resources. The objective of this paper is to investigate the factors that affect the genetic resources related investment decisions under the Nagoya Protocol. Specifically, we construct the model of Sharpley value and benefit sharing rate in order to consider the results of benefit sharing with a providing country under the Real Options, and simulate the model in the context of Madagascar Banana project. The results show that the product time to market, benefit sharing rate, and discount rate significantly influence the investment decisions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.5
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• pp.74-81
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• 2019

This study reports the CW $CO_2$ laser scribing of soda lime glass. In this study, scribing experiments are carried out at different laser powers, scan speeds, and focal positions to investigate the effect of the process parameters on the interaction characteristics between a laser beam and glass. In particular, the interaction characteristics are analyzed and described with the input laser energy per unit length. According to the experimental results, the damage threshold for the glass surface was found to exist between 0.072 and 0.08 J/mm. The input laser energy in this region induced partial melting of the surface and grain-shaped cracks. These cracks tended to increase as the input laser energy increased. At the laser input energy larger than 1 J/mm, a huge crack propagating along the scan direction was produced, and the volume below the scribed area was fully melted. The growth of this crack finally resulted in the complete cutting of the glass at the input laser energy above 8 J/mm. It was found that both the width and depth of the scribed line increased with increasing input laser energy. For the beam focusing at the rear surface, the width of the scribed line varied irregularly. This could be ascribed to the increased asymmetry of the beam intensity distribution when the laser beam was focused at the rear surface. Under this condition, a large burr was only produced on one side of the scribed line.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.260-267
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• 2021

In this study, a carboxylate-based anionic surfactant SLEC-3 was prepared from coconut oil and the structure was elucidated by using FT-IR, ¹H-NMR and ¹³C-NMR analysis. Measurements of interfacial properties such as critical micelle concentration, static and dynamic surface tensions, emulsification index, and foam stability have shown that SLEC-3 is better in terms of interfacial activity and more effective in lowering interfacial free energy than those of SLES, which has been widely used as a conventional anionic surfactant in the detergent industry. Biodegradability, acute oral toxicity and dermal irritation tests also revealed that SLEC-3 surfactant possesses excellent mildness and low toxicity, indicating the potential applicability in detergents and cleaner products formulation.

• Progress in Superconductivity and Cryogenics
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• v.6 no.1
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• pp.12-17
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• 2004

High critical current density. $J_c$ over $1MA/cm^2$ at 77 K in a self field was successfully achieved from the YBCO film prepared on (100) $SrTiO_3$ single-crystal substrates by the TFA-MOD process. Unlike a normal TFA-MOD process, we prepared the TFA precursor solution by dissolving YBCO powder into the trifluoroacetic acid. A significant amount of the second phases, including $BaF_2$, was observed in the films fired at $700-725^{\circ}C$ for 2 h under $P(O_2)=10^{-3}$ atm and $P(H_2O)=4.2%$, most probably due to an insufficient reaction time, and hence $T_c$ was greatly degraded. However the films fired at $750-800^{\circ}C$ for 2 h were composed of strongly c-axis oriented YBCO grams without any second phases. and exhibited the $T_c$ values of 89.5 ~ 91 K with a sharp transition. With increasing the firing temperature from 750 to $800^{\circ}C$ average grain size of YBCO was increased and grain connectivity was enhanced. The highest $J_c$ value of $1.1MA/cm^2$ was obtained from the YBCO film fired at $800^{\circ}C$.

• Journal of the Korean Geotechnical Society
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• v.40 no.4
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• pp.81-90
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• 2024

With the discovery of energy resources such as water ice on the Moon's surface, the Moon is attracting attention as an outpost for deep space exploration. As the concept of in situ resource utilization (ISRU) for establishing sustainable deep space exploration outposts gains traction, there is an increasing demand for technology to solidify lunar regolith as an in situ resource. In this study, sintered blocks were manufactured using a hybrid microwave sintering furnace. The effects of system configuration and dwell time on the microwave sintering efficiency were assessed. The results indicated that the composition of the SiC susceptor and its distance from the magnetron influenced the manufacturing of homogeneous sintered blocks. Additionally, varying the dwell time at a sintering temperature of 1,080℃ under optimal conditions revealed that exceeding the threshold dwell time caused the sintered blocks to become heterogeneous, thereby reducing the sintering efficiency.