• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.837-844
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• 2015

Carob waste is a useful raw material for the second-generation ethanol because 50% of its dry weight is sucrose, glucose, and fructose. To optimize the process, we have studied the influence of the initial concentration of sugars on the fermentation performance of Saccharomyces cerevisiae. With initial sugar concentrations (S₀ ) of 20 g/l, the yeasts were derepressed and the ethanol produced during the exponential phase was consumed in a diauxic phase. The rate of ethanol consumption decreased with increasing S₀ and disappeared at 250 g/l when the Crabtree effect was complete and almost all the sugar consumed was transformed into ethanol with a yield factor of 0.42 g/g. Sucrose hydrolysis was delayed at high S₀ because of glucose repression of invertase synthesis, which was triggered at concentrations above 40 g/l. At S₀ higher than 250 g/l, even when glucose had been exhausted, sucrose was hydrolyzed very slowly, probably due to an inhibition at this low water activity. Although with lower metabolic rates and longer times of fermentation, 250 g/l is considered the optimal initial concentration because it avoids the diauxic consumption of ethanol and maintains enough invertase activity to consume all the sucrose, and also avoids the inhibitions due to lower water activities at higher S₀ .

• Journal of the Korean Chemical Society
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• v.25 no.4
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• pp.283-290
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• 1981

The reaction rates for the transesterification reaction were measured on the excess sucrose with the five fatty acid methyl ester systems such as methyl laurate, methyl myristate, methyl palmitate, methyl stearate and methyl oleate at temperature range of $50^{\circ}C$ to $90^{\circ}C$ in N,N-dimethylformamide solvent and potassium carbonate as a catalyst. Their activation parameters as well as rate constants were calculated from these measurements. And these reactions were found to be pseudo-first order and depended mainly on the structural changes in fatty acid residue of methyl esters. Also their reactions were found to be of enthalpy-controlled, which were disfavored in the order of methyl laurate, methyl myristate, methyl palmitate, methyl oleate and methyl stearate. Correspondingly their activation energies were 9.3, 9.9, 10.3, 10.9 and 11.1 kcal/mole, respectively.

• IMMUNE NETWORK
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• v.2 no.4
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• pp.195-201
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• 2002

Background: IgE is closely related to the development of allergies. However, the poor relationship between the specific IgE level and the severity of allergic diseases suggests the possibility of functionally different IgE isoforms. With this in mind, rat basophilic leukemia (RBL)-2H3 activation was analyzed with each type of rat IgE for two parameters, exocytosis and IL-4 mRNA production. RBL-2H3 has been well documented in the rat mucosal mast cell line. Methods: RBL-2H3 cells sensitized with each kind of rat IgE was activated by cross-linking FcRI with B5 (monoclonal anti-rat IgE mouse IgG antibodies). The RBL-2H3 exocytosis was measured by analyzing the ${\beta}$-hexosaminidase level, and the level of IL-4 mRNA synthesis was analyzed using semiquantitative RT-PCR. Rat IgE, which was produced by a parasite infection (REP), was prepared using either Paragonimus westermani metacercariae (REP-PW) or Anisakis simplex third stage larvae (REP-AS). A rat IgE prototype of IR162 was prepared by a peritoneal injection of immunocytoma. Results: The level of exocytosis showed a linear relationship with the rat IgE concentration when REP-PW or REP-AS was applied. However, it exhibited a biphasic response with IR162. In addition, the time course of heating at $56^{\circ}C$ illustrated the similarity between REP-PW and REP-AS, which differed from that of IR162. In contrast, the level of IL-4 mRNA synthesis in the RBL-2H3 cells with IR162 was comparable to that of either REP-PW or REP-AS. Conclusion: These results suggest that functionally different rat IgE isoforms exists in RBL-2H3 exocytosis.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.221-227
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• 2014

In this paper, we propose a synthesis method that can effectively suppress the ambience which affects tonal components in the PS decoder. Ambience component was obtained by using decorrelation filter and the weighting of the ambience in the decoder was determined through IC parameter. However, since the parameters are extracted in the sub-band domain, a low IC value could be analyzed even if the tonal component is dominant. The quality of the output signal may be degraded. To prevent this problem, the tonality was measured in the downmixed signal and the weighting of the ambience components were adjusted appropriately according to the measured tonality index. The performance of the proposed method was evaluated by simulations. Furthermore, the subjective test was performed and the results confirmed that the proposed method offers improved quality.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.77-80
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• 2018

Silver nanoparticles with various sizes were synthesized using ionic liquids. In order to conduct more efficient research, experimental methods and results were analyzed statistically. First, effects of five different parameters including the reaction time, temperature, NaOH concentration, reducing agent and ionic liquid amount on the size of silver particles were investigated. As a result, the effects of time and temperature were negligible. The experimental conditions for the other three factors were then statistically constructed. From XRD analyses, the particles synthesized under all conditions had a pure silver crystal structure. Sizes of the synthesized silver particles were also analyzed by HR-SEM. In the three synthetic conditions, NaOH concentration had the greatest influence on determining the size of silver particles and the reducing agent concentration was relatively minute. Synthesis conditions of silver particles with various sizes were presented by using statistical methods with respect to NaOH and ionic liquids. In addition, the sizes of silver particles according to three experimental conditions were derived by the mixture method.

• Advances in Energy Research
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• v.2 no.1
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• pp.33-45
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• 2014

Photocatalytic hydrogen generation by water splitting ($H_2O_{(1)}{\rightarrow}H_2_{(g)}+1/2O_2_{(g)}$) has been studied on photocatalysts based on Zn, Cd, Fe and Cu, synthesized by coprecipitation. Iron and copper nanoparticles were incorporated as cocatalysts to enhance the photocatalytic activity of the ZnCd solid solution. The effect of the different synthesis parameters (temperature, elemental atomic ratios, amount of Cu and Fe incorporated in the catalyst and calcination temperature) on the photocatalytic production of hydrogen has been studied in order to determine the best experimental synthesis conditions. The catalysts have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and BET. The experiments of photocatalytic water splitting were performed in aqueous solution of the photocatalysts previously dispersed in a soft ultrasound bath. The photocatalysts were irradiated under different lights ranging from 220 to 700 nm. The photocatalytic activity was found to be clearly dependent on the specific area of the photocatalyst.

• The Journal of the Acoustical Society of Korea
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• v.14 no.5
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• pp.63-73
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• 1995

The conventional acoustic sounds can be synthesized by Frequency Modulation which includes the variation of frequency, amplitude, and modulation index. In this paper the number of variable synthesis parameters are limited to easily implement the existing two carrier FM algorithm by hardware. The DSP(Digital Signal Processor), which is able to carry out the modified algorithm and synthesize 16 sounds at a time, is designed with $0.8{\mu}m$ standard sells. The DSP which can synthesize 2 sounds at a time is implemented by ASIC emulator to examine the sound quality of the designed DSP. Through the objective and subjective estimation, it is confirmed that the sounds of many instruments from the implemented DSP are very closed to their real sound. Finally the designed DSP is layouted and simulated by VLSI desgn tool. According to the simulation, the designed DSP has the sufficiently fast speed for synthesizing 16 sounds at a time.

• Korean Journal of Materials Research
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• v.21 no.8
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• pp.415-418
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• 2011

Tin (IV) dioxide ($SnO_2$) has attracted much attention due to its potential scientific significance and technological applications. $SnO_2$ nanoparticles were prepared under low temperature and pressure conditions via precipitation from a 0.1 M $SnCl_4{\cdot}5H_2O$ solution by slowly adding $NH_4OH$ while rapidly stirring the solution. $SnO_2$ nanoparticles were obtained from the reaction in the temperature range from 130 to $250^{\circ}C$ during 6 h. The microstructure and phase of the synthesized tin oxide particles were studied using XRD and TEM analyses. The average crystalline sizes of the synthesized $SnO_2$ particles were from 5 to 20 nm and they had a narrow distribution. The average crystalline size of the synthesized particles increased as the reaction temperature increased. The crystalline size of the synthesized tin oxide particles decreased with increases in the pH value. The X-ray analysis showed that the synthesized particles were crystalline, and the SAED patterns also indicate that the synthesized $SnO_2$ nanoparticles were crystalline. Furthermore, the morphology of the synthesized $SnO_2$ nanoparticles was as a function of the reaction temperature. The effects of the synthesis parameters, such as the pH condition and reaction temperature, are also discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3C
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• pp.251-256
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• 2009

In this paper, we propose a new method with the improved continuity performance of overlap and add speech signal synthesis method using damping harmonic amplitude parameter. The existing method uses the average value of past and current parameters for the sinusoidal amplitude used as the weight of phase error function. But, the proposed method extracts the more accurate sinusoidal amplitude by using a correlation between the original signals and the synthesized signals for the sinusodal amplitude used as the weights. To verify the performance of the proposed method, we observed the average differential error value between the synthesized signals.

• Composites Research
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• v.16 no.3
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• pp.68-74
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• 2003

In this paper, intermetallic/metal laminated composites have been successfully produced that utilizes SHS reactions between Ni and Al elemental metal foils. The reaction between Ni and Al started from the nucleation and growth of NiA1$_3$ and was followed by the diffusional growth of Ni$_2$A1$_3$ between Ni and NiA1$_3$. The SHS reaction was thermodynamically analyzed through the final volume fraction of the non-reacted Al related with the initial thickness ratio of Ni:Al and prior heat treatment. Thermally aging these 1aminates resulted in formation of a functionally gradient series of intermetallic phases. Microstructure showed that the intermetallic volume percent was 82, 59.5, 40% in the 1:1, 2:1, 4:1 thickness ratio specimen. Main phases of the intermetallic were NiAl and Ni$_3$Al having higher strength at room and high temperatures.