• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.62-68
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• 2011

In the study, acrylate copolymer as MMA-co-GMA-co-AA with a high hardness and flexibility was synthesized for applying to the clear protection film, where GMA was used as a mediator to enhance polymerization-efficiency between MMA and AA. With an increase of GMA content, molecular weight and hardness of acrylate copolymer increased, however, flexibility decreased. With an increase of AA content, its molecular weight and hardness decreased, however, flexibility increased. Molar ratio of GMA/MMA and AA/GMA were optimized as 1.6 and 1.8, respectively, at 30 g of MMA to enhance hardness and flexibility of acrylate copolymer film. Molecular weight and Tg of the acrylate copoylmer were 13,300 g/mol and 136.5 $^{\circ}C$, respectively. Hardness of the coated film at 1.4 g/$m^2$ of spread was 1 H and no crack was observed at expansion ratio of 5% and 15%, respectively. Hardness of film was improved to 3 H by increasing spread of 4.1-4.6 g/$m^2$.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.433-439
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• 2012

In this study, a cationic surfactant BHMAS (N,N-bis-(3'-n-dodecyloxy-2'-hydroxypropyl)-N-methyl-2-hydroxyethylammonium methyl sulfate) having two lauryl and three hydroxyl groups was synthesized by the reaction of n-dodecyl glycidyl ether and 2-aminoethanol followed by the quarternization with dimethyl sulfate. The structure of the product was elucidated by $^{1}H-NMR$ and FT-IR. The CMC (critical micelle concentration) and surface tension of BHMAS at CMC condition were found to be $9.12\;{\times}\;10^{-4}$ mol/L and 28.71 mN/m respectively. Dynamic surface tension measurements using a maximum bubble pressure tensiometer indicated that a relatively long time was required to saturate the interface between air and aqueous surfactant solution. The interfacial tension measured between 1 wt% surfactant solution and n-decane reached an equilibrium value of 0.045 mN/m in 5 min. The adsorption capacity of the synthesized surfactant was observed to be excellent, which suggests that the surfactant can be used as a softening agent during a laundry process.

• Membrane Journal
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• v.22 no.6
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• pp.404-414
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• 2012

In order to investigate $SO_2$ removal, PEI hollow fiber membranes were produced by a dry-wet phase inversion method. The membrane support layer on surface was coated with PEBAX1657$^{(R)}$ and PEG blending materials. Modules were prepared for the single gas permeation characteristics of composite membrane according to temperature and pressure. As a result, $SO_2$ permeance and $SO_2/N_2$ selectivity were 220~1220 GPU and 100~506 through operating condition, respectively. Moreover, $SO_2/CO_2/N_2$ mixture gas was used to compare the performance of separation properties according to temperature, pressure and retentate flow rate difference. $SO_2$ removal efficiency was increased with pressure and temperature.

• Science of Emotion and Sensibility
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• v.14 no.1
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• pp.157-164
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• 2011

Emotion science is one of the rapidly expanding engineering/scientific disciplines which has a major impact on human society. Such growing interests in emotion science and engineering owe the recent trend that various academic fields are being merged. In this paper we propose the potential importance of the biochip technology in which the human emotion can be precisely measured in real time using body fluids such as blood, saliva and sweat. We firstly and newly name such a biochip an Emotion-On-a-Chip (EOC). EOC consists of biological markers to measure the emotion, electrode to acquire the signal, transducer to transfer the signal and display to show the result. In particular, microfabrication techniques made it possible to construct nano/micron scale sensing parts/chips to accommodate the biological molecules to capture the emotional bio-markers and gave us a new opportunities to investigate the emotion precisely. Future developments in the EOC techniques will be able to help combine the social sciences and natural sciences, and consequently expand the scope of studies.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.539-544
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• 2020

A three-dimensional (3D) porous polyaniline (PANI) film was fabricated by a combined photo-and soft-lithography technique based on a large-area nanopillar array, followed by a controlled chemical dilute polymerization. The as-obtained 3D PANI film consisted of hierarchically interconnected PANI nanofibers, resulting in a 3D hierarchical nanoweb film with a large surface and open porous structure. Using electrochemical measurements, the resulting 3D PANI film was demonstrated as a flexible pH sensor electrode, exhibiting a high sensitivity of 60.3 mV/pH, which is close to the ideal Nernstian behavior. In addition, the 3D PANI electrode showed a fast response time of 10 s, good repeatability, and good selectivity. When the 3D PANI electrode was measured under a mechanically bent state, the electrode exhibited a high sensitivity of 60.4 mV/pH, demonstrating flexible pH sensor performance.

• Journal of Life Science
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• v.21 no.7
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• pp.976-984
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• 2011

Total phenolic content was the highest in 60% ethanol extracts at 21.91 mg/g, and inhibitory activity against tyrosinase of 60% ethanol extracts was higher than ethanol extracts of other concentration. The inhibitory compounds against tyrosinase from Persimmon leaves were purified using Sephadex LH-20, MCI-gel CHP-20 column chromatography with gradient elution. Two purified compounds were isolated as a result. The chemical structures of each compound were determined and identified using $^1H$-NMR and $^{13}C$-NMR, FAB-Mass. The compounds were confirmed as (+)-gallocatechin and prodelphinidin B-3. The tyrosinase inhibitory activities of purified (+)-gallocatechin and prodelphinidin B-3 were 29.5 and 40.2%, respectively. The inhibitory activities of (+)-gallocatechin and prodelphinidin B-3 against melanin biosynthesis in melanoma cell were 32.5 and 46.7%. The safety of essence with tyrosinase inhibitory compounds from persimmon leaves was also assessed by various safety profiles. First, changes in pH (4.90~4.95) and viscosity (23,000~26,000 cP) was not detected for 60 days. Essence also showed stability against temperature and light for 60 days. All these findings suggest that extracts from persimmon leaves have a great potential as a cosmetical ingredient with a potent whitening effect.

• Polymer(Korea)
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• v.35 no.2
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• pp.161-165
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• 2011

This study is related to the preparation of biocompatible gold nanoparticles (AuNPs) which are stable in aqueous solutions for a long time. Ultrasmall polyethyleneimine (PEI)-capped AuNPs (PEI-AuNPs) with limited agglomeration were prepared in aqueous solutions at room temperature, which were based on the roles of PEI as a reductant and a stabilizer. PEI-AuNPs with an average size of 8~12 nm formed highly stable nanocolloids with an average hydrodynamic cluster size of around 50 nm in aqueous media. At a low concentration of metal precursor hydrogen tetrachloroaurate (III), the particle size was reduced noticeably. The typical peaks of gold were observed in the X-ray diffraction pattern of AuNPs. The cell viability of 98% was obtained in the case of PEI-AuNPs, while PEI was cytotoxic. The PEI-AuNP is considered to be a potential candidate as a contrast agent for computed tomography.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.582-587
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• 2012

In this paper, it was studied on the crystallization characteristics of PLA film by adding ammonium phosphate (APP) as a nucleation agent. Crystallinity and crystallite size of PLA film were determined by Scherrer equation. Crystallization rate constant of PLA film was calculated through Avrami equation. Film samples in the study were prepared by two steps. PLA films were prepared by adding 1, 5, and 10 wt%, respectively, at first and was secondly annealed at 130, 140, and $150^{\circ}C$. Crystallinity of pure PLA film was average 4.6% and those of PLA film with adding 1, 5, and 10 wt% APP were 12.2, 47.7, and 50.0%, respectively. Crystallite size of PLA film was average 28.0 nm and those of PLA film with adding 1, 5, and 10 wt% APP were 26.8, 24.0, and 19.0 nm, respectively. Crystallization rate constants of PLA film with 1 wt% APP were 2.12, 3.86, and 0.27 by annealing at 130, 140, and $150^{\circ}C$, respectively, where was higher than pure PLA film and those with adding 5 and 10 wt% APP, respectively.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.367-375
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• 2014

In this thesis we observe microvascular structure in mice by using micro-computed tomography (CT), which is high-resolution X-ray imaging equipment that can acquire Real-time dynamic image, and it aims to investigate the usefulness of micro-CT developed by Institute for Radiological Imaging Science Wonkwang University School of Medicine. After acquiring the systemic images of rats, contrast-enhanced 3D images of vascular structures could be acquired by using Maximum Intensity Projection (MIP) and Volume Rending Technique (VRT), This was divided into each vascular system of head, abdomen and heart and systemic vascular system.

• Food Science and Preservation
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• v.16 no.5
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• pp.765-771
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• 2009

Anti-oxidative activities of Heracleum moellendorffii Hance extracts were measured after extraction with 50% (v/v) ethanol or water (at $80^{\circ}C$ or $20^{\circ}C$). The total polyphenol content was highest (64.73 mg GAE/g) in extract from 50% ethanol extraction at $80^{\circ}C$. In extracts obtained by water extraction at $80^{\circ}C$ and $20^{\circ}C$, the total polyphenol contents were 39.78 mg GAE/g and 23.17 mg GAE/g, respectively. The antioxidant activities of the ethanol extract at $80^{\circ}C$ were highest, as assessed by DPPH radical scavenging activity (69.14% at 50 ppm), reducing power (OD 0.93), and $ABTS^+$ radical-scavenging activity (85.62% at 1,000 ppm). At $80^{\circ}C$, the antioxidant activity of the 50% (v/v) ethanol extract was 8-20% higher than that of the water extract. Also, the chemical composition of extract from ethanol extraction at $80^{\circ}C$ was analyzed. The levels of moisture, crude protein, crude fat, and crude ash were 6.38%, 4.35%, 0.67%, and 1.96%, (all w/w), respectively. The Na, K, Mg, Zn, Fe, Ca, and P contents of the extract were 53.41, 398.26, 5.80, 0.40, 5.27, 3.56, and 47.17 mg/100 g, respectively. The total levels of polyphenolic compounds and flavonoids in the ethanol extract were 64.73 mg GAE/g and 49.54 mg RE/g.