• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1246-1250
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• 2005

We have evaluated the hydroxyl group-solvent specific interactions by using a Lichrosorb RP18 stationary phase and by measuring the retention data of carefully selected solutes in 50/50, 60/40, 70/30, 80/20, and 90/10(v/v%) methanol/water eluents at 25, 30, 35, 40, 45, and 50 ${^{\circ}C}$. The selected solutes are 3 positional isomers of phenylpropanol, that is, 1-phenyl-1-propanol, 1-phenyl-2-propanol, and 3-phenyl-1-propanol. There exist clear discrepancies in ${\Delta}H^o$ (solute transfer enthalpy from the mobile to the stationary phase) and $T{\Delta}S^o$ (solute transfer entropy) among positional isomers. The difference in ${\Delta}H^o$ and $T{\Delta}S^o$ between secondary alcohols (1-phenyl-1-propanol and 1-phenyl-2-propanol)is negligible compared to the difference between the primary alcohol (1-phenyl-3-propanol) and secondary alcohols. The $T{\Delta}S^o$ values of 3-phenyl-1-propanol are close to those of butylbenzene while the $T{\Delta}S^o$ values of secondary alcohols are close to those of propylbenzene. The difference in ${\Delta}{\Delta}H^o$ (specific solute-mobile phase interaction enthalpy) between the primary alcohol and the secondary alcohol decreases with increase of methanol content in the mobile phase. A unique observation is an extremum for 1-phenyl-3-propanol in the plot of $T{\Delta}{\Delta}S^o$ vs. methanol volume %. The positive sign of $T{\Delta}{\Delta}S^o$ of 3-phenyl-1-propanol implies that the entropy of 3-phenyl-1-propanol is greater than that of the hypothetical alkylbenzene (the same size and shape as phenylpropanol) in the mobile phase.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2913-2917
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• 2009

Second-order rate constants (k$_{Nu–}$) have been measured for nucleophilic substitution reactions of Y-substituted phenyl benzoates (1a-i) with butane-2,3-dione monoximate ($Ox^-\;an\;\alpha$-nucleophile) and Z-substituted phenoxides in 80 mol% H$_2$O/20 mol% DMSO at 25.0${\pm}$0.1$^{\circ}C$. Hammett plots correlated with ${\sigma}^o$ and ${\sigma}^-$ constants for reactions of 1a-h with Ox$^–$ exhibit many scattered points. In contrast, the Yukawa-Tsuno plot results in a good linear correlation with ${\rho}_Y$ = 2.20 and r = 0.45, indicating that expulsion of the leaving group occurs in the rate-determining step (RDS). A stepwise mechanism with expulsion of the leaving-group being the RDS has been excluded, since Y-substituted phenoxides are less basic and better nucleofuges than Ox$^–$. Thus, the reactions have been concluded to proceed through a concerted mechanism. Ox$^–$ is over 10$^2$ times more reactive than its reference nucleophile, 4-chlorophenoxide (4-ClPhO$^–$). One might suggest that stabilization of the transition-state (TS) through intramolecular general acid/base catalysis is responsible for the ${\alpha}$-effect since such general acid/base catalysis is not possible for the corresponding reactions with 4-ClPhO$^–$. However, destabilization of the ground-state (GS) of Ox$^–$ has been concluded to be mainly responsible for the ${\alpha}$-effect found in this study on the basis of the fact that the magnitude of the ${\alpha}$-effect is independent of the nature of the substituent Y.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.8-22
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• 2014

In the past few decades, CMOS logic technologies and devices have been successfully developed with the steady miniaturization of the feature size. At the sub-30-nm CMOS technology nodes, one of the main hurdles for continuously and successfully scaling down CMOS devices is the parametric failure caused by random variations such as line edge roughness (LER), random dopant fluctuation (RDF), and work-function variation (WFV). The characteristics of each random variation source and its effect on advanced device structures such as multigate and ultra-thin-body devices (vs. conventional planar bulk MOSFET) are discussed in detail. Further, suggested are suppression methods for the LER-, RDF-, and WFV-induced threshold voltage (VTH) variations in advanced CMOS logic technologies including the double-patterning and double-etching (2P2E) technique and in advanced device structures including the fully depleted silicon-on-insulator (FD-SOI) MOSFET and FinFET/tri-gate MOSFET at the sub-30-nm nodes. The segmented-channel MOSFET (SegFET) and junctionless transistor (JLT) that can suppress the random variations and the SegFET-/JLT-based static random access memory (SRAM) cell that enhance the read and write margins at a time, though generally with a trade-off between the read and the write margins, are introduced.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.615-620
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• 2020

Oxide semiconductor, represented by a-IGZO, has been commercialized in the market as active layer of TFTs of display backplanes due to its various advantages over a-Si. a-IGZO can be deposited at room temperature by RF magnetron sputtering process; however, additional thermal annealing above 300℃ is required to obtain good semiconducting properties and stability. These temperature are too high for common flexible substrates like PET, PEN, and PI. In this work, effects of microwave annealing time on IGZO thin film and associated thin-film transistors are demonstrated. As the microwave annealing time increases, the electrical properties of a-IGZO TFT improve to a degree similar to that during thermal annealing. Optimal microwave annealed IGZO TFT exhibits mobility, SS, V_th, and V_H of 6.45 ㎠/Vs, 0.17 V/dec, 1.53 V, and 0.47 V, respectively. PBS and NBS stability tests confirm that microwave annealing can effectively improve the interface between the dielectric and the active layer.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.55-61
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• 2015

In this paper, the displacement behavior characteristic of hollow rollers with various cross sectional area profiles and circular plate for load supporting capacity increment has been presented using a finite element method. The FEM results present that the hollow roller with X-shaped or Y-shaped columns between outer tube, middle tube and inner tube reduces a maximum displacement at the middle length of hollow rollers. And the circular plate, which is inserted at the middle of the hollow roller, is very useful to reduce the maximum displacement of hollow rollers with the plate thickness of 30~40mm. This paper presents the weight vs the maximum displacement ratio in which is represented for the optimized design as a function of a hollow roller total weight. The FEM analyzed results recommend the design model 4, 5 and 6 of hollow rollers for decreasing the ratio of maximum displacement and total weight of hollow rollers.

• Parasites, Hosts and Diseases
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• v.51 no.1
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• pp.93-98
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• 2013

A field applicable diagnostic technique, the dipstick assay, was evaluated for its sensitivity and specificity in diagnosing human Schistosoma mansoni infection. A monoclonal antibody (mAb) against S. mansoni adult worm tegumental antigen (AWTA) was employed in dipstick and sandwich ELISA for detection of circulating schistosome antigen (CSA) in both serum and urine samples. Based on clinical and parasitological examinations, 60 S. mansoni-infected patients, 30 patients infected with parasites other than schistosomiasis, and 30 uninfected healthy individuals were selected. The sensitivity and specificity of dipstick assay in urine samples were 86.7% and 90.0%, respectively, compared to 90.0% sensitivity and 91.7% specificity of sandwich ELISA. In serum samples, the sensitivity and specificity were 88.3% and 91.7% for dipstick assay vs. 91.7% and 95.0% for sandwich ELISA, respectively. The diagnostic efficacy of dipstick assay in urine and serum samples was 88.3% and 90.0%, while it was 90.8% and 93.3% for sandwich ELISA, respectively. The diagnostic indices of dipstick assay and ELISA either in serum or in urine were statistically comparable (P>0.05). In conclusion, the dipstick assay offers an alternative simple, rapid, non-invasive technique in detecting CSA or complement to stool examinations especially in field studies.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1043-1050
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• 2000

The nutritional value of commercial instant noodles produced in summer and winter seasons were investigated. Only the noodle itself was used for the analysis. The content of carbohydrate was calculated by difference. The calorie was estimated by using a conversion factor of 4.32 for protein, 9.21 for fat and 4.20 for carbohydrate. Bag-type instant noodles had higher moisture, but lower content of fat and calorie compared with bowl-type products. No seasonal variations on composition and calorie were found. The calorie was negatively correlated with moisture or carbohydrate content, and positively correlated with fat content. The calorie estimated from linear regression equation of calorie vs. moisture was similar to the value calculated using a conversion factor, which implies that the calorie of the instant noodle can be simply estimated from the moisture content. The intakes of calorie from fat accounted for 30.8% and 34.1% from bag-type and bowl-type noodles, respectively. The content of ash and fat, and calorie were significantly decreased upon cooking, which were more pronounced in the bowl-type products. At the same moisture contents the loss of calorie for bag-type products was 3.5% and for bowl-type ones was 7.7%.

• Korean Journal of Community Nutrition
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• v.4 no.1
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• pp.30-36
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• 1999

This study was carried out to longitudinally investigate the iron and zinc intakes and correlation with growth performance of 25 male breast-and formula-fed infants from 1 to 3 months postpartum, longitudinally. There were four groups breast fed(BF) and three formula fed groups((FFM, FFN and FFP). Milk intakes and the concentration of iron and zinc from human milk and the formulas were measured. The iron content of human milk was $2.07\pm{1.05(0.63~5.65)}\mu{g}$/ml. The zinc content was $2.43\pm{1.14(0.70~5.30)}\mu{/ml.}$ Both were not significantly different among postpartum months. The average iron intake of the breast-fed and formula-fed infants was $1.6\pm{0.7mg/}$day and $8.4\pm{2.3mg}$/day, respectively. The iron intake of breast-fed infants was higher than previous reports. And that of formula-fed infants was higher than the RDA. The average zinc intake of the breast-fed group was $1.9\pm{0.9mg/}$day and formula-fed infants' was $2.7\pm{0.7mg/}$day, which was higher than the RDA. There was no correlation between these mineral intakes and the growth performance during 1 to 3 postpartum months. So, extensive studies of the iron content of human milk and wide cross-sectional studies for establishing iron and zinc recommended dietary allowances for infants are needed.

• Journal of Environmental Science International
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• v.30 no.10
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• pp.789-802
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• 2021

This study analyzed the characteristics of high PM_2.5 episodes that meets the concentration criteria of Emergency Reduction Measures Plan (ERMP) in Busan during the 2015-2020, and compared with those in Seoul. As a first step, the CAPSS-2017 emission data was employed to analyze the emission differences between Busan and Seoul, and pointed out that Busan emission included the dominance of ship emissions (37.7%) among total PM_2.5 city emissions, whereas fugitive PM_2.5 emission was the highest in Seoul. These emission characteristics are indicating that the controlling action plan should be uniquely applied to cope with ERMP in each region. We selected extremely high PM_2.5 episode days that meet the criteria of ERMP levels. In Busan, Ulsan, and Gyeongnam region, 15, 16, and 8 days of extremely high PM_2.5 cases were found, respectively, whereas Seoul showed approximately doubling of occurrences with 37 cases. However, the occurrences in summer season indicated big differences between two cities: the proportion of summer-season occurrence was 13-25% in Busan, whereas no single case have occurred in Seoul. This is suggesting the needs of comprehensive summer emission reduction plan with focusing on sulfur reduction to effectively cope with the ERMP levels in summer in the southeastern region, including Busan.

• Investigative and Clinical Urology
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• v.59 no.6
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• pp.416-421
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• 2018

Purpose: Few studies have explored the treatment of isolated communicating hydroceles via scrotal incision. We prospectively evaluated the surgical outcomes of such treatment in boys with hydroceles compared with that using traditional, inguinal incision hydrocelectomy. Materials and Methods: Of 347 boys aged 0-12 years who were diagnosed as hydrocele on ultrasonography, 173 boys were assigned to the scrotal incision hydrocelectomy group (group I, n=173) and 172 boys were assigned to the traditional inguinal incision hydrocelectomy group (group II, n=172), and finally 156 boys in group I and 156 boys in group II were included in this study. Surgical outcomes, including postoperative complications and hydrocele relapse rates, were compared between groups. Results: The overall success rates were similar in both groups (group I, 96.8%; group II, 89.1%; p=0.740). The operation time and hospital stay were significantly shorter in group I ($30.94{\pm}3.95minutes$ and $3.94{\pm}0.30days$) than in group II ($38.02{\pm}7.12minutes$ and $4.24{\pm}0.99days$; p<0.001 and p=0.009, respectively). The postoperative complication rate was lower in group I than in group II (3.2% vs. 10.9%, p=0.740). Conclusions: Scrotal incision hydrocelectomy in boys was associated with shorter operative time and hospital stay, and a lower postoperative complication rate, than was the inguinal incision approach. The scrotal incision technique might be an easy and effective alternative treatment when used to treat hydroceles in boys as well as inguinal incision approach.