• KSBB Journal
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• v.15 no.5
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• pp.452-457
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• 2000

Due to the advantage of RP-HPLC with a variety of compositions of mobile phases, experiments on water-soluble charged species were examined. The samples were mononucleotides (5-CMP, 5-UMP, 5-GMP, 5-IMP, 5-AMP), and the buffers used were sodium phosphate monobasic and acetic acid. The concentrations of buffers ranged from 0.01 to 10 mM, while that of the methanol, an additive to the mobile phase was 5 to 20 vol.%. To predict the retention factor of a sample in terms of its methanol composition (M, vol.%) and buffer(C(sub)B, mM), the following nonlinear equation is suggested, k= $\frac{a+b C_B}{(1+c C_B) M^d}($ where a, b, c, and d were experimentally determined constants. The regression coefficients were above 0.96, and the agreement between experimental and calculated retention factors were relatively good.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.211-218
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• 2006

This work deals with 24 substances composed of nitrogen-containing heterocycles. The relationships between the chromatographic retention factor (k) and those physicochemical properties which are relevant in quantitative structure-properties relationship (QSPR) studies, such as the polarizability $(\alpha)$, molar refractivity (MR), lipophilicity (logP), dipole moment $(\mu)$, total energy $(E_{tot})$, heat of formation $(\Delta H_f)$, molecular surface area $(S_M)$, and binding energy $(E_b)$, were investigated. The accuracy of the simple linear regressions between the chromatographic retention and the descriptors for all of the compounds was satisfactory (correlation coefficient, $0.8 \leq r \leq 1.0$). The QSPR models of these nitrogen-containing heterocyclic compounds could be predicted with a multiple linear regression equation having the statistical index, r = 1.000. This work demonstrated the successful application of the multiple linear approaches through the development of accurate predictive equations for retention factors in liquid chromatography.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1757-1762
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• 2003

The interrelation between retention factors of several L-amino acids and their physico-chemical and structural properties can be determined in chromatographic research. In this paper we describe a predictor for retention factors with various properties of the L-amino acids. Eighteen L-amino acids are included in this study, and retention factors are measured experimentally by RP-HPLC. Binding energy ($E_b$), hydrophobicity (log P), molecular refractivity (MR), polarizability (${\alpha}$), total energy ($E_t$), water solubility (log S), connectivity index (${\chi}$) of different orders and Wiener index (w) are theoretically calculated. Relationships between these properties and retention factors are established, and their predictive and interpretive ability are evaluated. The equation of the relationship between retention factors and various descriptors of L-amino acids is suggested as linear and multiple linear form, and the correlation coefficients estimated are relatively higher than 0.90.

• Culinary science and hospitality research
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• v.12 no.4 s.31
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• pp.18-32
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• 2006

This research is to figure out how interpersonal relationships among the foodservice industry affected customer satisfaction and retention. Marketing strategy methods could be indicated to bear fruit in the food-industry based on this research. First, the properties of each factor related interpersonal relationship of foodservice industry, customer satisfaction and retention were obtained from previous studies. Second, interpersonal relationship was applied as an independent variable, retention between customers and the foodservice industry as a consequent variable and customer satisfaction as a parameters. The result reached through convergent validity came to satisfy all variables. Third, it was strongly maintained that the higher interpersonal relationship was, the more satisfied customers were and that the more satisfied customers were, the stronger retention was. It was shown that customers would repurchase and had strong loyalty to a certain enterprise if its services satisfied them and met their expectations.

• Culinary science and hospitality research
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• v.14 no.2
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• pp.99-114
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• 2008

The purpose of this study is to examine the relationships between each type of attitudes toward money and the attributes of choosing family restaurants. A self-administrated questionnaire was completed by 387 students, and data were analysed by frequency, factor, reliability and canonical correlation. Seven factors were obtained from factor analysis of attitudes toward money; Factor 1 "power", Factor 2 "obsession", Factor 3 "retention", Factor 4 "achievement", Factor 5 "anxiety", Factor 6 "distrust", and Factor7 "evaluation". The attributes of family restaurant choice were extracted into six factors: Factor 1 "quality of food", Factor 2 "restaurant event", Factor 3 "interior environment", Factor 4 "value of food", Factor 5 "convenience for approach", and Factor 6 "employees' service". Canonical correlation analysis showed three significant functions. Canonical function 1 showed that the attitudes of considering the power of money, its retention and achievement were indicated to have significantly positive relationships with the quality of food in the attributes of choosing family restaurants. Canonical function 2 showed that significantly negative relationships between distrust and restaurant events and convenience for approach. Canonical function 3 also showed that significantly positive relationships between obsession and anxiety and the interior of restaurants and employees' service, and significantly negative relationships between evaluation and the interior of restaurants and employees' service.

• KSBB Journal
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• v.19 no.4
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• pp.263-268
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• 2004

The separation method using chiral stationary phase in preparation of chiral compound was wildly used, but in this work, supercritical fluid chromatography was suggested in the stability to resolve the chiral mixtures. To determine the optimum operating condition of the racemic ibuprofen, the retention factor and resolution with change in pressures, temperatures and the contents of IPA % (vol.) in CO$_2$ were investigated. The retention factor was decreased with increase in pressure and decrease in temperature. The factor was also influenced by the content of IPA in mobile phase, while the resolution was worse with a increase in IPA %. From the experimental results, the desirable separation condition was 130 bar, 311.15 K and 4% IPA in CO$_2$. Compared to the asymmetric peak shape by liquid chromatography, that of supercritical fluid chromatography was symmetric which was a favorable condition for preparative separation.

• KSBB Journal
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• v.20 no.4
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• pp.260-265
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• 2005

In this work, molecular imprinted polymers (MIPs) using the template of the N-CBZ (carbobenzyloxy)-L-phenylalanine, MAA and 4-VPY as a monomer, EGDMA as a crosslinker and AIBN as an initiator were considered. The prepared polymer particles $(Ca.\;25-35\;{\mu}m)$ were packed into a chromatographic column $(3.9\;\times\;150\;mm)$. The chromatographic characteristics of the retention on the MIP were experimented with acetonitrile as a mobile phase at the flow rate of mobile phase, 0.5 ml/min. The retention factors and resolutions of chiral racemate of the N-CBZ-D, L-phenylalanine were measured. The results showed that the retention factor and resolution by the two co-monomer imprinting polymer were higher than the single monomer imprinting polymers, which indicated an increase in the affinity of the MIP with the sample as a result of the cooperation effect of the binding sites.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.E
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• pp.47-58
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• 1990

Abstract A regionalized daily streamflow model using a modified retention parameter in the SCS method was developed to predict the daily streamflow of a natural series for Korean watersheds. Model verification showed that it is possible to use the model for extending short period records in a gaged watershed or for predicting daily streamflow in any ungaged watershed, with reasonable accuracy by simply inputing the name of the watershed boundary, the watershed size, the latitude and longitude of the watershed, and the daily areal rainfall.

• Food Science of Animal Resources
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• v.30 no.6
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• pp.1024-1030
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• 2010

The focus of the study was to maximize the output data for Korean cuisine. This study evaluated the nutritional retention factor for different cuts of Korean beef (Hanwoo beef) subjected to various cooking methods. Five cuts (short rib, sirloin, chuck roll, tenderloin, and fore shank) of Korean Hanwoo beef were prepared and used in this experiment. Two different cooking methods (dry-heat cooking and moisture-heat cooking) were applied to each cut. The sodium contents of dry-heat cooked short rib (86.44), sirloin (76.81), tenderloin (86.65), and fore shank (85.89) decreased. Potassium contents of dryheat cooked sirloin (94.99), chuck roll (89.19), and fore shank (92.66) decreased. Calcium contents of dry-heat cooked sirloin (61.49), chuck roll (73.97), and fore shank (91.46) decreased. Iron contents of dry-heat cooked chuck roll (79.71), and tenderloin (90.79) decreased. Phosphorus contents of dry-heat cooked sirloin (87.87), and tenderloin (99.88) decreased. Mineral contents of all cuts cooked by moisture-heat decreased. Finally, the nutritional retention factor represents output data of each cooking method with yield % of each item.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1265-1268
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• 2003

The estimation of retention factors by correlation equations with physico-chmical properties maybe helpful in chromatographic work. The physico-chemical properties were water solubility (S), hydrophobicity (P), total energy ($E_t$), connectivity index 1 ($^1{\chi}$), hydrophilic-lipophlic balance (x) and hydrophilic surface area (h) of isoflavones. The retention factors were experimentally measured by RP-HPLC. Especially, the empirical regulations of water solubility and hydrophobicity were expressed in a linear form. The equation between retention factors and various physico-chemical properties of isoflavones was suggested as $k = a_0 + a_1\;log S + a_2log\;P^Q + a_3(E_t) + a_4(^1{\chi}) + a_5(x) + a_6(h)$, and the correlation coefficients estimated were relatively higher than 0.95. The empirical equations might be successfully used for a prediction of the various chromatographic characteristics of substances, with a similar chemical structure.