• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.3
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• pp.9-17
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• 2001

The floc characteristics of base paper stock for coating by the retention aid system consisting of polyacrylamide (high molecular weight low charge density, HMLC) and PEI without and with anionic inorganic oxide (IO) were investigated under various shear conditions of MDDA (modified dynamic drainage analyzer). The floc size was increased with cationic electrolytes dosage whatever inorganic oxide is applied or not. The effect of inorganic oxide on the floc size showed the different result between PAM and PEI. The smaller floc was obtained by PAM without inorganic oxide, but larger floc was obtained by PAM with inorganic oxide. However, the effect of shear force was not observed. Floc formation index was decreased by the addition of cationic electrolytes with or without inorganic oxide. Floc formation index had better correlation format formation index than floc size. The relationships between wet web permeability and mat air permeability showed the significant linear correlation ($R^2$=0.97~0.98) for HML PAM and PEI. Floc formation index gave more useful information than the retention measurement when the performance of retention aids is evaluated at the laboratory before applying at the paper mill.

• 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.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1703-1707
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• 2013

A fast and simple sampling and sample preparation device, (NTD) has been developed and applied to sample and analyze volatile components from ground coffee beans. Coffee fragrances and other volatile organic compounds (VOCs) were sampled by the NTD and then analyzed by gas chromatograph-mass spectrometry (GC/MS). Divinylbenzene (DVB) particles (80/100 mesh size) were the sorbent bed of the NTD. More than 150 volatile components were first identified based on the database of the mass library and then finally 30 fragrances including caffeine were further confirmed by comparing experimental retention indices (i.e. Kovat index) with literature retention indices. Total sampling time was 10 minutes and no extra solvent extraction and/or reconstitution step need. Straight n-alkanes (C6-C20) were used as retention index probes for the calculation of experimental retention indices. In addition, this report suggests that an empty needle can be an alternative platform for analyzing polymers by pyrolysis-GC/MS.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.1
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• pp.48-53
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• 2010

Commercial micro pulps(Arbocel) were coated with three kinds of polymers using spray method. These coated micro pulps were used to papermaking additives to evaluate retention, drainage and physical properties of paper. The retention and drainage were improved with addition of polymer coated micro pulp. The bulk index of paper was also increased, but tensile and tear strength were decreased slightly, probably due to weakening of internal bonding. These results showed that the use of polymer coated micro pulp was an effective method to improve retention, drainage and bulk index of paper.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.135-144
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• 2019

This study was conducted in order to be applied to basic data for enhancing dental hygienists' retention intention. Data analysis was carried out a univariate analysis and a hierarchical regression analysis over 3 stages by using SPSS version 19.0. The dental hygienists' retention intention showed a high outcome in case of the married(p<.001), in the more positive emotion(p<.001), in the lower frequency of emotional expression(p=.010), in the higher happiness index with life satisfaction(p<.001) and in the higher psychological happiness index(p=.012). The dental hygienists' emotion, emotional labor and happiness index need to be recognized as important relevant factors for increasing retention intention.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.1
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• pp.20-25
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• 1994

The volatile components were extracted from root of Cnidium officinale M. by SDE(Simultaneous steam distillation and extraction) apparatus and analyzed by GC/M.5 and GC retention index matching. The experimental results revealed the presence of over 22 volatile components. Major components were cnidilide (35.1%), neocnidilids (13.4%), ligustilide (23.2%). The essential oils were separated by silica gel column chromatography(Merck 70-230mesh), and 4 fractions among 12 fractions separated had a, good aroma character.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.315-320
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• 1996

In this paper, we investigated the retention amounts(ash contents) according to the addition amounts of retention aid and calcium carbonate and compared the mechanical and optical properties of sheets under the same ash content. As the addition amounts of retention aid increase, the retention of calcium carbonate, that is, ash contents of sheets increase in all retention system. In this case, the sheets included ash content as already expected is produced by adjusting the addition amounts of retention aid and calcium carbonate. Tensile index, burst index, tear index, internal bonding strength of sheets straightly decrease as the ash content of sheets increases. Especially, in the same ash content, all sorts of strength are high in compozil system, low in dual polymer system. Opacity increases along with according to the increase of ash content, and is high in hydrocol system, the worst in dual polymer system. In equal opacity, the strength of paper decreases compozil, hydrocol, and dual polymer system in order. But to judge she superiority or inferiority of retention aids, it should consider the various factors such as the optimum production and process conditions besides the retention amounts of filler and the sheet strength.

• The korean journal of orthodontics
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• v.42 no.5
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• pp.255-262
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• 2012

Objective: We aimed to compare the retention characteristics of Essix and Hawley retainers. Methods: Adolescents undergoing fixed appliance treatment at 2 centers were recruited for this study. Twenty-two patients (16 women and 6 men) wore Essix retainers (Essix group) while 20 (14 women and 6 men) wore Hawley retainers (Hawley group). The mean retention time was 1 year, and the mean follow-up recall time for both groups was 2 years. Two qualified dental examiners evaluated the blind patient data. Maxillary and mandibular dental casts and lateral cephalograms were analyzed at 4 stages: pretreatment (T1), post-treatment (T2), post-retention (T3), and follow-up (T4). Results: The results revealed that Essix appliances were more efficient in retaining the anterior teeth in the mandible during a 1-year retention period. The irregularity index increased in both arches in both groups after a 2-year post-retention period. The mandibular arch lengths increased during treatment and tended to return to their original value after retention in both groups; however, these changes were statistically significant only in the Hawley group. Cephalometric variables did not show any significant differences. Conclusions: The retention characteristics of both Essix and Hawley retainers are similar.

• Analytical Science and Technology
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• v.8 no.4
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• pp.519-527
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• 1995

The retention mechanism of Ni(II)-${\alpha}$-isonitroso-${\beta}$-diketone imine chelates in reversed-phase HPLC has been studied by examining the effect of temperature, mobile phase composition in acetonitrile-water mixture, and molecular structure on retention. The empirical retention equation was investigated to evaluate the properties of S (hydrophilic index). The value of the S index of the Ni(II) chelates decrease with the increasing column temperature and a linear relationship between S and log $k{_w}^{\prime}$ has been found. The results showed that the S index is influenced by the interaction between Ni(II) chelates and mobile phase. Molecular properties, van der Waals molar volume, polarizability and dipole moment, of the Ni(II) chelates were calculated by Cerius 2 program and the calculations were performed at Universal Force Field (UFF) model. The S value and log $k{_w}^{\prime}$ increase with decreasing the dipole moment of Ni(II) chelates.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.357-363
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• 1994

We evaluated the diagnostic accuracy of $^{99m}Tc$-DISIDA scintigrauhy as a mean of differentiating biliary atresia from neonatal hepatitis. $^{99m}Tc$-DISIDA scintigraphy was visually interpreted by assessing the presence or absence of radioactivity in the intestine or gall bladder. In patients without intestinal radioactivity, we measured the hepatic retention index and the hepatic uptake index. The hepatic retention Index was expressed as the amount of change of liver activity from 5 minutes to 30 minutes postinjection. The hepatic uptake Index was graded visually with 5 minute images using the following scoring scheme : grade 0(normal hepatic uptake), grade 1(decreased hepatic uptake), grade 2(hepatic uptake equal to cardiac uptake), and grade 3(hepatic uptake less than cardiac uptake). Age, total bilirubin, and hepatic uptake index were compared between the biliary atresia and the neonatal hepatitis group, between neonatal hepatitis patients with and without intestinal radioactivity, and between the biliary atresia and neonatal hepatitis patients with absent intestinal radioactivity. The results were as follows ; 1) None of the 30 biliary atresia patients showed intestinal radioactivity, while 31/40 neonatal hepatitis patients showed intestinal radioactivity. The sensitivity, specificity, and accuracy of the presence of intestinal radioactivity ?or the diagnosis of biliary atresia was 100%, 78%, and 87%, respectively. 2) In patients with absent intestinal radioactivity the mean hepatic retention index was $1.5{\pm}0.6$ in the 16 biliary atresia patients, and $1.1{\pm}0.2$ in the 7 neonatal hepatitis patients(p<0.01). All 7 patients with hepatic retention index over 1.5 had biliary atresia. But there were 9 patients with biliary atresia below 1.5. 3) No significant differences were found in age, total bilirubin, or hepatic uptake Index between biliary atresia and neonatal hepatitis patients. However there were differences in age, total bilirubin, and hepatic uptake index between neonatal hepatitis patients with and without intestinal radioactivity. The hepatic uptake index was significantly lower, age was old, and total bilirubin was low in the group with intestinal radioactivity compared the group without intestinal radioactivity(p<0.05). Relation between total bilirubin and the hepatic uptake index was that total bilirubin was relatively low at normal hepatic uptake index in biliary atresia and neonatal hepatitis patients. 4) When hepatic uptake index and hepatic retention index were high it suggest that biliary atresia is more likely, considered relation between hepatic uptake Index and the hepatic retention index. Thus, we conclude that $^{99m}Tc$-DISIDA scintigraphy is accurate in the differential diagnosis of biliary atresia and neonatal hepatitis. In patients without intestinal radioactivity, the hepatic retention index and hepatic uptake index, along with the patient's age and total bilirubin level may supplement diagnosis and improve diagnostic accuracy.