• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.302-309
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• 1980

The solubilities of n-propyl bromide in nitrobenzene and in 1,2,4-trichlorobenzene have been measured at 19, 25 and $40^{\circ}C$ in the presence and absence of gallium bromide. When gallium bromide does not exist in the system, the solubility of n-propyl bromide in nitrobenzene is greater than in 1,2,4-trichlorobenzene, indicating a stronger interaction of n-propyl bromide with nitrobenzene than with 1,2,4-trichlorobenzene. In the presence of gallium bromide, 1: 1 complex $n-C_3H_7Br\cdotGaBr_3$ is formed in the solution. The instability constant K of the complex was evaluated. $$n-C_3H_7Br\cdotGaBr_3 \rightleftarrows n-C_3H_7Br ＋ \frac{1}{2Ga_2Br_6 }$$The change of enthalpy, free energy and entropy for the dissociation of the complex were also calculated. It seems that the stabilities of the complex, gallium bromide with alkyl bromide, are relatively concerned with the stabilities of the alkyl ion.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.246-249
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• 2007

In numerical analysis for phase change material, numerical values of thermodynamic properties such as temperature, pressure, specific volume, enthalpy and entropy are required. But the steam table or diagram itself cannot be used without modelling. In this study applicability of neural networks in modelling superheated vapor region of water was examined by comparing with the quadratic spline. neural network consists of an input layer with 2 nodes, two hidden layers and an output layer with 3 nodes. Quadratic spline interpoation method was also applied for comparison. Neural network model revealed smaller percentage error to quadratic spline interpolation. From these results, it is confirmed that the neural networks could be powerful method in modelling the superheated range of the steam table.

• Analytical Science and Technology
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• v.8 no.2
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• pp.107-116
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• 1995

The critical micelle concentration(CMC) of CTAB was determined with changes in absorbance at 202nm band of 4-biphenyl acetate($BPA^-$). With $BPA^-$ as a probe, the effect of temperature on CMC of CTAB has been observed between $30^{\circ}C{\sim}70^{\circ}C$. In this range of temperature the values of CMC are $1.18{\times}10^{-4}{\sim}2.02{\times}10^{-4}M$. The free energy(${\Delta}G^{\circ}m$) and enthalpy(${\Delta}H^{\circ}m$)for the micellization of CTAB was negative and the entropy(${\Delta}S^{\circ}m$) was a large positive value. The micellization of CTAB is considered as a spontaneous process and to involve a phase transition. The orientational binding of 4-biphenyl acetate anion to the CTAB micelle interface has been studied with $300MHz\;H^1-NMR$ data. The change in chemical shift of proton in CTAB as well as those of the protons in $BPA^-$ have been investigated by increasing the mole fraction of the anion in the mixed solutions. The changes in chemical shift with increasing mole fraction of anion($BPA^-$) indicate the formation of mixed micelle between CTAB and $BPA^-$. The changes in chemical shifts of methylene protons in CTAB, demonstrate the penetration of $BPA^-$ into the palisade layer of the CTAB micelle.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.179-188
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• 2020

The influx of marine exotic and alien species is disrupting marine ecosystems and aquaculture. Herdmania momus, reported as an invasive species, is distributed all along the coast of Jeju Island and has been confirmed to be distributed and spread to Busan. The potential habitats and distribution of H. momus were estimated using the maximum entropy (MaxEnt) model, quantum geographic information system (QGIS), and Bio-ocean rasters for analysis of climate and environment(Bio-ORACLE), which can predict the distribution and spread based only on species occurrence data using species distribution model (SDM). Temperature and salinity were selected as environmental variables based on previous literature. Additionally, two different representative concentration pathway (RCP) scenarios (RCP 4.5 and RCP 8.5) were set up to estimate future and potential habitats owing to climate change. The prediction of potential habitats and distribution for H. momus using MaxEnt confirmed maximum temperature as the highest contributor(77.1%), and mean salinity, the lowest (0%). And the potential habitats and distribution of H. momus were the highest on Jeju Island, and no potential habitat or distribution was seen in the Yellow Sea. Different RCP scenarios showed that at RCP 4.5, H. momus would be distributed along the coast of Jeju Island in the year 2050 and that the distribution would expand to parts of the Korea Strait by the year 2100. RCP 8.5, the distribution in 2050 is predicted to be similar to that at RCP 4.5; however, by 2100, the distribution is predicted to expand to parts of the Korea Strait and the East Sea. This study can be utilized as basic data to effectively control the ecological injuries by H. momus by predicting its spread and distribution both at present and in the future.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.2
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• pp.63-73
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• 2020

Purpose: To investigate breathing-related changes in the balance ability of healthy adults. Methods: The participants were 36 healthy adults in their 20s and 30s. All participants were trained in three breathing (neutral, thoracic, and abdominal) methods one week before measurements. We used AccuSway to measure each participant's balance ability, using each breathing technique, in two postures (bipedal and unipedal). Results: During the bipedal balance task, abdominal breathing produced significant increases in path length and sway velocity. Abdominal breathing resulted in significant changes in sample entropy at the anteroposterior location compared with neutral breathing (p<.05). In the normalized anteroposterior location, there were significant changes in backward movement during thoracic and abdominal breathing compared with those during neutral breathing (p<.05). During the unipedal balance task, path length and sway velocity increased significantly during voluntary breathing compared with those during neutral breathing (p<.05). There was a significant change in backward movement when abdominal breathing-compared with neutral breathing-was used in the normalized anteroposterior location (p<.05). In the normalized left-right location, there was a significant shift to the right during thoracic breathing compared with that during neutral breathing (p<.05). Conclusion: Compared with neutral breathing, altered voluntary breathing patterns affect balance in healthy adults. Our results indicated that that static balance was more affected by abdominal breathing than by neutral breathing. Future studies should examine variables such as the breathing volume, rhythm, and method.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.590-598
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• 2016

In this study, the adsorption behavior from aqueous solution as well as kinetic and thermodynamic parameters of Acid Black 1 were investigated through batch reaction using coconut shell based granular steam activated carbon. The effects of various adsorption parameters such as pH, initial concentration, contact time, temperature were studied. To confirm the effect of pH, pHpzc measurements were analyzed followed by measuring removal efficiencies of Acid Black 1 at the pH range from 3 to 11. Experimental equilibrium adsorption data were fitted using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich adsorption isotherm. The conformity of adsorption reaction for pseudo first and second order model were evaluated through kinetic analysis. Values of enthalpy change and activation energy were also investigated through thermodynamic analysis and it was confirmed that the adsorption process was endothermic. The spontaneity of adsorption process was evaluated using the values of entropy and Gibbs free energy changes.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.41-46
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• 1984

The pectic enzymes produced from Aspergillus niger were separated into three fractions (F-A, F-I and F-II) by means of Sephadex and DEAF-Sephadex column chromatography. Each enzyme fraction was characterized by determining viscosity change and reducing surgar of the pectic acid-enzyme mixture and analyzing thin layer chromatogram of the reaction products. F-I rapidly reduced the viscosity of pectic acid solution and released reducing groups in a random manner so that appeared to be an endo-polygalacturonase (endo-PG). The optimum pH of endo-PG for viscosity reducing activity was 4.2 and that for releasing reducing surgar was 4.7. In the thermal inactivation of endo-PG of $30-45^{\circ}C$, the enthalpy of activation was 217.3 kj/mole and z-value was $7.5^{\circ}C$. F-II and F-A were determined as endo-polymethylgalacturonase and exo-polygalacturonase, respectively.

• Journal of the Korean Chemical Society
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• v.29 no.1
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• pp.9-14
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• 1985

The solubilities of i-propyl bromide in nitrobenzene have been measured at 10$^{\circ}$, 19$^{\circ}$ and 25$^{\circ}C$ in the presence and absence of gallium bromide. In the presence of gallium bromide, 1 : 1 complex, i-C$_3$H$_7Br{\cdot}GaBr_3$ is formed in the solution. The instability constant K of the complex formation was evaluated from the following equilibrium equation: i-C$_3$H$_7Br{\cdot}GaBr_3$ ${\rightleftharpoons}$ i-C$_3$H$_7$Br + $\frac{1}{2}$$Ga_2Br_6$. The change of enthalpy, free energy and entropy for the dissociation of the complex were also calculated. From these result, it seems that the stabilities of the complex formation, gallium bromide with alkyl bromide, are directly related with those of the carbonium ions of alkyl bromide.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.2
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• pp.56-68
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• 2002

The Universal Variable Length Coding(UVLC) scheme in H.26L has nice features such as error resiliency and two-way decodability. However, it has lower coding efficiency than the conventional Huffman coding. To improve the coding efficiency of UVLC, we Propose to use a dynamic codeword mapping that changes association between symbols and codewords in order to utilize the statistical characteristics of symbols as much as possible but without losing any features of the UVLC. Both encoder and decoder use the same re-association table, and hence the encoder need not send additional overhead for the re-mapping relationship to the decoder. Simulation results show that without significant change of the current H.26L coding scheme, the proposed method additionally attains up to about 8% and about 5% bit reductions respectively in intra and inter frames over the current H.26L encoding method.

• Journal of the Korean Chemical Society
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• v.24 no.2
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• pp.150-154
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• 1980

Kinetic studies of the reaction of benzyl benzenesulfonate with pyridine in acetone were carried out by the electric conductivity method under 1 to 2000 bars and at 20 to $40^{\circ}C$. The rate increases with increasing pressure and temperature. The activation enthalpy $({\Delta}H^{\neq}),\;entropy\;({\Delta}S^{\neq})$ and activation volume $({\Delta}V^{\neq})$ of the reaction are obtained by the above experiment. The isokinetic relationship between $({\Delta}H^{\neq})\;and\;({\Delta}S^{\neq})$ for pressure change in the reaction was shown, and its isokinetic temperature was $342^{\circ}K$. From all of the above results it was found that this reaction precedes on the $S_N2$ reaction mechanism in which the rate of the reaction was determined by $C{\cdots}N$ bond formation at transition state.