• 한국해양학회지
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• 제5권1호
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• pp.1-5
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• 1970

The hydration numbers of some salts present in sea water have been calculated by a simple model for the equation of the dielectric constant, and the mean activity coefficients from the theoretical formula proposed by Jhon and Eyring. The validity of the theory for the electrolyte solution is tested by evaluating the hydration numbers and the mean activity coefficients of some 1:1, 1:2, 2:1 and 1:3 electrolytes in sea water. The results show good agreement with the observations.

• Bulletin of the Korean Chemical Society
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• 제24권11호
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• pp.1708-1710
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• 2003

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3709-3714
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• 2013

Based on the Debye-H$\ddot{u}$ckel equation, a semi-empirical equation for activity coefficients was derived through empirical and theoretical trial and error efforts. The obtained equation included two parameters: the proportional factor and the effective radius of an ionic sphere. These parameters were used in the empirical and regression parameter fitting of the calculated values to the experimental results. The activity coefficients calculated from the equation agreed with the data. Transforming to a semi-empirical form, the equation was expressed with one parameter, the ion radius. The ion radius, ${\alpha}$, was divided into three parameters, ${\alpha}_{cation}$, ${\alpha}_{anion}$ and ${\delta}_{cation}$, representing parameters for the cation, anion and combination, respectively. The advantage of this equation is the ability to propose a semi-empirical equation that can easily determine the activity coefficient with just one parameter, so the equation is expected to be used more widely in actual industry applications.

• 한국응용과학기술학회지
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• 제17권2호
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• pp.132-138
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• 2000

Excess enthalpies ($H^{E}$) were measured by isothermal flow calorimetry for the nonionic amphiphile 2-butoxyethanol/water mixtures at 10 different temperatures (48.5 to $70^{\circ}C$) around and above the lower consolute solution temperature, $T_{lc}$. $H^{E}$ exhibits U-shape for the binary mixtures, and is large and negative which reflects substantial interaction between two chemical species. When the commonly used, semi-empirical Redlich-Kister (RK) polynomials were fitted to the measured $H^{E}$, plots of $H^{E}$ vs. weight fraction provided more accurate fitting with fewer parameters than conventionally drawn $H^{E}$ vs. mole fraction plots. This was due to the enhanced symmetry of $H^{E}$ vs. weight fraction plots. Using the fitted Redlich-Kister polynomials and the Gibbs-Helmholtz relation, temperature dependence of the activity coefficients were found and compared to the values determined from vapor-liquid equilibria. The activity coefficients were in the range of one to three, indicating that the binary system deviates from ideality but not substantially. They slightly depended on temperature and the temperature effect was equivalent to 10 % change in the activity coefficients.

• The Korean Journal of Ceramics
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• 제4권2호
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• pp.90-94
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• 1998

Self diffusion coefficients of $^{67}$Co and impurity diffusion coefficients of $^{51}$Mn and $^{65}$Zn in single crystalline CoO have been measured by applying different radioactive isotopes simultaneously. To compare the residual activity method and the tracer sectioning method we analyzed our tracer diffusion experiments by using both methods simultaneously. According to our experimental results, the diffusion coefficients obtained from both methods are identical within experimental error, demonstrating the relibility of our experimental procedures. The diffusion coefficients of all the isotopes obtained during these test experiments for the methodology are similar in magnitude and show similar dependences on oxygen partial pressure. These first observations indicate that impurity diffusion of Mn and Zn occur via a vacancy mechanism as known for self diffusion of cobalt.

• Korean Chemical Engineering Research
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• 제50권1호
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• pp.93-105
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• 2012

본 연구에서는 무기염인 NaCl, KCl, $NaNO_3$ 및 $KNO_3$의 각 전해질과 L형 아미노산인 L-Valine 및 L-Proline이 용해된 아미노산/전해질 수용액에서 L-Valine 및 L-Proline의 활동도계수와 용해도를 298.15 K에서 측정하였다. 아미노산의 활동도계수는 양이온 및 음이온의 선택성 전극간의 기전력을 측정하는 전기화학 법으로 측정하였으며, 용해도는 아미노산의 고체상과 상평형을 이루고 있는 포화용액을 중량 분석하여 측정하였다. 실험적으로 측정된 전해질 및 아미노산의 활동도계수 값을 본 연구의 저자들이 수행한 지난번 연구[Korean Chem. Eng. Res. 48(4), 519(2010)]의 이론적 모델로 검토하였다. 실험을 수행한 8개의 아미노산/전해질 수용액에서 측정된 전해질 및 아미노산의 활동도계수 값은 지난번 연구의 이론적 모델에 잘 적용되는 경향을 보였으며, 또한 측정된 아미노산의 용해도 데이터도 지난번 연구의 이론적 관계로 잘 묘사될 수 있었다.

• 산업기술연구
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• 제20권A호
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• pp.185-194
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• 2000

In this work we measured the total pressure of the aqueous solutions and the methanol-water solutions dissolved with inorganic salts, at $25^{\circ}C$. In organic electrolytes used in this work were $K_2SO_4$ and $(NH_4)_2SO_4$. Using the measured vapour pressures the activity coefficient of solvents and the mean ionic activity coefficient were obtained through thermodynamic relations. The activity coefficients of solvent and the mean ionic activity coefficirnt obtained in this work were fitted with Macedo's model and Acard's model. Both two models were good agreeable to the vapor pressure and the mean ionic activity coefficient for the electroyte aqueous solutions. For electrolyte /methanol/water solutions, Macedo's model had much deviation from experimental data, while Acard's model showed a good agreement with experimental data.

• 대한지역사회영양학회지
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• 제12권3호
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• pp.361-371
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• 2007

The purpose of this study was to assess the daily steps, physical activities and activity coefficient of the elementary school children in the rural area. Body weight, height and daily steps were measured and one-day activity diaries were collected by interviewing children. The average age of the subjects was $9.96{\pm}1.02$ years. Average height, weight, obesity index, body fat and muscle of subjects were $136.2{\pm}8.9cm,\;35.2{\pm}8.5kg,\;99.6{\pm}18.8%,\;22.9{\pm}8.5%\;and\;35.8{\pm}6.0%$, respectively. The average daily steps of the subjects was 17,584 and daily steps (19,314) of 3rd grade students was significantly higher than that (15,712) of 5th grade children. But there was no significant difference in daily steps and activity coefficients between boys and girls. Daily steps (23,347) of exercise group showed the significantly higher than that (16,144) of non-exercise group. Gender and grade of subjects did not have significant influence on activity coefficients, but there was a significant difference in activity coefficient on weekdays between the exercise group ($1.82{\pm}0.30$) and non-exercise group ($1.50{\pm}0.21$). Analysis of variance revealed stronger associations between daily steps and body fat (%) than between daily steps and BMI. Daily steps showed significant negative correlation with body fat (%) measured using two methods r=-0.321 and r=-0.365, respectively. Activity coefficient was significantly correlated (r=0.436) with daily steps, thus increasing daily steps cm prevent and treat childhood obesity by increasing the energy expenditure. The higher activity coefficients (weekday 1.56, weekend 1.53) of the subjects was caused by the fact that rural students spent more time outside and enjoyed stronger activities than urban students. The results of this study can be used to estimate energy requirements for Korean children based on exercise levels and living areas.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.519-533
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• 2010

본 연구에서는 L-형 아미노산인 L-Alanine과 무기염인 NaCl, KCl, $NaNO_3$ 및 $KNO_3$의 각 전해질로 이루어진 L-Alanine/전해질 수용액 계에서 L-Alanine의 활동도계수와 용해도를 298.15 K에서 측정하였다. L-Alanine의 활동도계수는 양이온 및 음이온의 선택성 전극으로 이루어진 화학전지에서 두 전극간의 기전력을 측정하는 전기화학 법으로 측정하였으며, 용해도는 L-Alanine의 고체상과 상평형을 이루고 있는 포화용액을 중량 분석하여 측정하였다. 한편 본 연구에서는 아미노산(L-Alanine)/전해질 수용액 계의 잔류(residual) Helmholtz 자유에너지를 섭동사슬-통계역학적 회합성유체이론(perturbed chain-statistical associating fluid theory)과 단순-평균구근사(primitive-mean spherical approximation)이론을 결합한 관계로 모델링 하였으며, 이로부터 아미노산의 활동도계수 및 용해도에 대한 열역학적 관계식을 얻었다. Helmholtz 자유에너지를 모델링 하는 과정에서는 아미노산은 양쪽성 이온(zwitterion) 형태로 존재하며 아미노산의 양쪽성 이온은 같은 이온끼리 자기-회합(self-association)하며 동시에 물분자와 교차-회합(cross-association)하는 회합체로 가정하였으며, 또한 아미노산의 양쪽성 이온이 전해질(무기염)로부터 해리된 양이온 및 음이온과 상호작용하여 이온복합체(ion complex)를 형성하는 과정을 회합현상으로 가정하였다. 본 연구에서 제안된 이론적 모델로부터 L-Alanine/전해질 수용액 계에서 계산되는 L-Alanine의 활동도계수 및 용해도 값은 본 연구의 실험값과 일치하는 경향을 보였다.

• 대한화학회지
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• 제6권2호
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• pp.113-116
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• 1962

In this study we have measured the activity coefficients of NaCl in solution by E.M.F. method, depending upon MacInnes' equation at 25 dog. The cell (electrodes) is same as MacInnes' except the cock which was designed by ourselves as figure 1.Additionally, we have calculated the hydration number of NaCl from the activity coefficients using Robinson's equation and ionic hydration number according to our new formula $\frac{n_M{^+}+0.8}{n_A{^-}-0.1}=n_{MA}$, which was mentioned our former thesis.We also have calculated the hydration number of some salts from the ionic hydration number using upper formula and have got reasonable series match with other's value.As the results of our studying, we conclude it as follow;1) Liquid junction potential depend only on the bulk concentration of the both solution.2) The formula $\frac{n_M{^+}+0.8}{{n_A{^-}}-0.1}=n_{MA}$ is reasonable one in deducing to ionic hydration number.3) From upper relation, we can calculate the hydration number of unknown salts from it's ionic hydration numbers.