• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.15-20
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• 1994

The adsorption model in reversed phase liquid chromatography has been critically examined. It has been found that use of the Everett type surface activity coefficient for the solute in the stationary phase is not useful to study the retention characteristics of a nonpolar solute. We suggest a modified model. In this model it is assumed that the displaced modifier molecules from the surface monolayer do not transfer into the bulk mobile phase but stick to the nonpolar solute which has displaced them. In addition, we prefer to use an apparent stationary phase activity coefficient of the soluie instead of the Everett type activity coefficient. This modified adsorption model well explains the mobile and stationary phase effects on the solute retention upon variation of mobile phase composition.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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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.

• Journal of the Korean Dietetic Association
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• v.12 no.1
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• pp.44-54
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• 2006

The study was conducted to assess the energy expenditure of 102 elementary school children. Body weight and height were measured and one-day activity diaries were collected by interviewing with children. The children spent about 9 hours 14 minutes sleeping ; 3 hours 40 minutes resting. They spent 86.4% of 24 hours (one day) in 'very light activities' and 13.3% in 'light activities'. Activity coefficient (1.41$\pm$0.11) of boys was significantly higher than that of girls(1.35$\pm$0.07). Activity coefficient (1.41$\pm$0.11) of 4th grade elementary school children was higher than those of 2nd and 6th grade school children(p<0.05). Resting energy expenditure estimated by Harris-Benedict formula, formula based on body surface area and DRI formula for Koreans were 1240.9$\pm$147.4kcal/day, 1386.5$\pm$206.9kcal/day and 1284.5$\pm$199.8 kcal/day. And daily energy expenditure by using Harris-Benedict formula, body surface area formula and DRI formula were 1708.4$\pm$258.8kcal, 1909.8$\pm$341.8kcal and 1771.1$\pm$341.9kcal/day. These results suggested that nutrition and exercise program to increase the energy expenditures of primary school children should be developed.

• Korean Journal of Community Nutrition
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• v.16 no.2
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• pp.195-205
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• 2011

This study was conducted to investigate the time spent, activity coefficient and energy expenditure on 7 different types of activity. Total of 386 5th and 6th grade primary school boys and girls in Seoul participated in this study. The participants spent 8 hrs for rest, 4 hrs for out of school study, 3 hrs for leisure, 1 hr 45 mins. for hygiene, 1 hr for commute, and 15 mins. for house choir activity in the day of 6 class hours. The average activity coefficient of 1 day for boys and girls were 1.69 and 1.64, respectively. The TEEs were 2,382 kcal and 2,050 kcal for boys and girls, respectively. The energy cost for study related activity (in school and study activities) was 40% of the TEE, and for rest 20%, for commute 9%, and for hygiene 10% of the TEE. The energy cost for house choir was only about 2% of TEE. The 91.2% participant's EER was higher than the EER shown in the table of 2010 DRI for Koreans. When the participant's EER was compared with the energy allowance calculated by the method in 2000 RDA for Korean, 81.6% was in the range of ${\pm}5%$, and the correlation coefficients between the 2 values were 0.981 for boys and 0.978 for girls, which means high agreements.

• Korean Journal of Community Nutrition
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• v.14 no.6
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• pp.777-788
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• 2009

The purpose of this study was to assess physical activities and activity coefficient of preschool children and was to give some concrete information to activate outdoor play and to probe the suggestions to activate outdoor play. 42 preschool children (17 boys and 25 girls) were included. Body weight and height were measured and one-day activity diaries were collected by interviewing with their parents and kindergarten teachers. To measure physical activity during outdoor play, this study was researched the current conditions and content of outdoor play activity in daycare centers, and teacher's perceptions of that outdoor play. The average age of the subjects was 5.0 years. Average height, weight, body fat and body muscle of subjects were 108.9 cm, 18.9 kg, 17.7% and 26.8%, respectively. The subjects spent about 10 hours 39 minutes sleeping; 4 hours 16 minutes personal hygiene and computer working. They spent 88.2% of 24 hours (one day) in "very light activities" and 11.3% in "light activities". Activity coefficient (1.34) of weekday was significantly higher than that of weekend (1.21). And in this study, it was found that most of daycare centers (87.7%) have outdoor play space, 95.2% of them were garden. The teachers recognized that have a outdoor play frequency everyday (48%), three or four times (46%) in a week but they have three or four times (38%), one or two times (30%) because of various indoor program. Also, they recognized that have a outdoor play expending time 21-30 minutes (48%), 31-40 minutes (26%) but they have 21-30 minutes (64%). They answered that have frequency and expending time less than their recognition of outdoor play. Most of daycare center teachers perceived outdoor play to be as important as indoor play, and the teachers believed outdoor play supports children's physical, cognitive, social, and language development. The results of this study may be used to utilize as a basic data for estimate physical activity for preschool children and developed that exercise program to increase physical activity of daycare center outdoor play.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.652-659
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• 2017

In the present research, in order to predict activity coefficient of inorganic ions in electrolyte solution of a petroleum system, we studied 13 components in the electrolyte solution, including $H_2O$, $CO_2$ (aq), $H^+$, $Na^+$, $Ba^{2+}$, $Ca^{2+}$, $Sr^{2+}$, $Mg^{2+}$, $SO_4$, $CO_3$, $OH^-$, $Cl^-$, and $HCO_3$. To predict the activity coefficient of the components of the petroleum system (a solid/liquid equilibrium system), activity coefficient model of Extended UNIQUAC was studied, along with its adjustable parameters optimized based on a genetic algorithm. The total calculated error associated with optimizing the adjustable parameters of Extended UNIQUAC model considering the 13 components under study at three temperature levels (298.15, 323.15, and 373.15 K) using the genetic algorithm is found to be 0.07.

• International Journal of Safety
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• v.10 no.1
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• pp.5-9
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• 2011

Two popular activity coefficient models, Wilson and NRTL equations have been used to correlate the published flash point data on the n-propanol + propionic acid and n-butanol + propionic acid systems through the optimization method. The results of these correlation were compared with the results calculated by Raoult's law. The optimization method were found to be better than those based on the Raoult's law. The optimization method based on the Wilson equation described the published data more effectively than was the case when the optimization method was based upon the NRTL equation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1747-1753
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• 2010

In this study, a comparative study was performed to predict the vapor-liquid equilibria with maximum azeotropic pressure for ethanol-benzene binary system between an equation of state model and a liquid activity coefficient model. Peng-Robinson equation of state model with a Panatiotopoulos mixing rules (PRP) was used and NRTL liquid activity coefficient model proposed by Renon was selected. The PRP model, even though it has only two binary adjustable parameters, was not inferior to the NRTL model to predict vapor-liquid equilibria for low pressure region of ethanol-benzene system and showed a better prediction capability for high pressure region of ethanol-benzene system than the NRTL model with three binary interaction parameters.

• Mass Spectrometry Letters
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• v.1 no.1
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• pp.13-16
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• 2010

The active components in a plant extract can be represented as mass profiles. We introduce here a new, multi-compound discovery method known as Scaling of Correlations between Activity and Mass Profiles (SCAMP). In this method, a correlation coefficient is used to quantify similarities between the extract activity and mass profiles. The method was evaluated by first measuring the anti-oxidation activity of eleven fractions of an Astragali Radix extract using DPPH assays. Next, 15 T Fouriertransform ion cyclotron resonance (FT-ICR) MS was employed to generate mass profiles of the eleven fractions. A comparison of correlation coefficients indicated two compounds at m/z 285.076 and 286.076 that were strong antioxidants. Principal component analyses of these profiles yielded the same result. FT-ICR MS, which offers a mass resolving power of 500,000, was used to discern isotopic fine structures and indicated that the molecular formula corresponding to the peak at m/z 285.076 was $C_{16}H_{13}O_5$. SCAMP in combination with high-resolution MS can be applied to any type of mixture to study pharmacological activity and is a powerful tool for active compound discovery in plant extract studies.

• Korean Journal of Community Nutrition
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• v.9 no.3
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• pp.285-291
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• 2004

The purpose of this study was to compare the energy expenditure and energy intake of normal-weight and overweight Korean adults. We recruited 242 adults to determine resting energy expenditure, physical activity and energy intake. Resting energy expenditure was measured by indirect calorimetry. Energy intake for consecutive two days was assessed by 24 hour recall method. Daily activity pattern for 24 hour was collected from each subject. Body weight, lean body mass and percentage body fat were measured by INBODY 3.0. The subject were divided into normal ($20\leqBMI$ ＜ 25) and overweight ($BMI \geq 25$) groups by BMI. There was no significant difference in intake of energy between two groups. Energy intake of each group was lower than the 7th Korean RDA of energy. Overweight subjects showed significantly lower REE/kg body weight. However, REE/kg lean body mass (LBM) did not differ between the two groups. Total activity energy was significantly higher in the overweight group compared to the normal group. Daily activity coefficient of overweight group in male was lower than that of normal group. Daily activity coefficient was almost same in two female groups. LBM was highly correlated with REE and total energy expenditure. We concluded that the overweight group consumed more energy than the normal group due to the heavier body weight.