• YAKHAK HOEJI
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• v.56 no.5
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• pp.280-287
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• 2012

A high-performance liquid chromatography (HPLC) combined with ultraviolet (UV) method for the simultaneous determination of ${\alpha}$-cyperone and nootkatone was developed for the quality control of Cyperus rotundus Linne. The separation was performed on a KR100-$5C_{18}$ ($4.6{\times}250mm$) column, and an elution gradient composed of methanol and water with a flow-rate of 1.0 ml/min. Detection wavelength was set at 254 nm. The optimum extraction for the detection of the ${\alpha}$-cyperone and nookatone was achieved by ultrasonic with methanol for an hour. Two marker compounds ${\alpha}$-cyperone and nootkatone in Cyperi Rhizoma showed good linearity ($R^2$ >0.999) in the concentration range of $12.5{\mu}g/ml$ to $200{\mu}g/ml$. The developed method provided satisfactory precision and accuracy with overall intra-day and inter-day variations of 0.04~1.23% and 0.08~0.68%, respectively, and the overall recoveries of 97.45~105.58% for the two compounds analyzed. Additionally, a difference was observed in the cluster analysis and principal component analysis between Cyperi Rhizoma in Korea and China. The result demonstrated that the principal component analysis is useful to distinguish between Cyperi Rhizoma in Korea and China.

• Analytical Science and Technology
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• v.34 no.5
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• pp.212-224
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• 2021

The intent of the present work was to develop a simple, sensitive, accurate, precise, rapid and economical UV- spectrophotometric and reverse phase high pressure liquid chromatographic method for the simultaneous estimation of Spironolactone and Furosemide in bulk and combined tablet dosage forms. UV-Spectrophotometry was carried out by simultaneous equation method using 0.02 M potassium dihydrogen phosphate buffer pH 3.5: Acetonitrile (50:50) v/v as a solvent. The linearity range was 2-14 ㎍ mL^-1 for Spironolactone and Furosemide with a correlation coefficient > 0.99. The chromatographic separation was achieved on 250 mm × 4.6 mm, hypersil BDS C18 column with particle size 5 ㎛, by using an isocratic mixture of 0.02 M potassium dihydrogen phosphate buffer pH 3.5: Acetonitrile: tert butyl methyl ether (49:50:1) v/v/v as a solvent at a flow rate of 1 mL min^-1 and UV detection was carried out at 254 nm. The retention time were observed to be 3.666 and 6.661 minutes for Furosemide and Spironolactone respectively. The two developed methods were validated according to the ICH guidelines for accuracy, precision, linearity, LOD, LOQ and were found to be within the limits. It can be concluded that these two methods could be successfully used for the simultaneous estimation of Spironolactone and Furosemide in bulk and combined tablet dosage forms.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.254-254
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• 2015

가시광선에 대해 선택적으로 투과할 수 있는 스마트 윈도우를 제작하기 위해 우리는 전기 에너지를 이용하여 유리의 색을 조절할 필요가 있다. 특히 환원되면서 가시광선 파장의 흡광도를 증폭시켜 색을 변화시키는 무기물질들이 존재하는데, 이러한 특성을 가진 균일한 박막을 만들 경우 그 표면적을 달리 하는 것이 중요하다. 이번 연구에서 우리는 Polystyrene 단일층을 만들어 WOx의 나노구조체 template를 만드는 연구를 진행하였다. 먼저, WOx nanorod 졸을 ITO 위에 스핀코팅 기법을 이용하여 도포시키고, 이후 단일 크기의 PS beads를 monolayer로 올렸다. 이 때의 PS beads의 크기는 400 ~ 1800nm의 크기를 이용하였다. 만들어진 monolayer에 다시 WOx sol을 도포시켜 반구형의 template를 갖는 WOx를 제작하였다. 우리는 이러한 방식으로 만들어진 Tungsten oxide 나노 구조체의 전기변색 특성이 어떻게 달라지는지 확인했다. 결정형 분석을 위해 XRD를 분석했고 투과도와 표면상을 보기 위해 UV-visible과 FE-SEM을 이용하였으며 마지막으로 Cyclic Voltametry를 이용해 전기변색특성 변화를 알아보았다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.254-254
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• 2009

Single-walled carbon nanotubes (SWCNTs) have attracted much attention as promising materials for transparent conducting films (TCFs), thanks to their superior electrical conductivity, high mechanical strength, and complete flexibility. The CNT-based TCFs can be used in a variety of application fields as flexible, transparent electrodes, including touch panel screens, flexible electronics, transparent heaters, etc. First of all, this study investigated the effect of a variety of surfactants on the dispersion of SWCNTs in an aqueous solution. Following the optimization of the dispersion by surfactants, flexible TCFs were fabricated by spraying the CNT suspension onto poly(ethylene terephthalate) (PET) substrates. The sheet resistances of the TCFs having different surfactants were investigated with treatment in nitric acid ($HNO_3$) whose concentration and period of treatment time were varied. It seems that the $HNO_3$ removes the surfactants from and is simultaneously doped into the SWCNT network, reducing the contact resistance between CNTs. TCFs were characterized by UV-VIS spectroscopy, thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), and four-point probe.

• Polymer(Korea)
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• v.24 no.3
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• pp.407-417
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• 2000

Photosensitive polyimides having cyclobutane or phenyl and aromatic sulfonyloxyimide units in the main chain have been synthesized and the photodegradation behavior was investigated in relation with the polymer structure. The polyimides were prepared by condensation polymerization of N-hydroxyl and sulfonyl chloride. The prepared polyimides were stable up to 25$0^{\circ}C$ without thermal degradation. It has been found that the photodegradation of polyimides upon irradiation of 254 nm UV light results from scission of N-O bonds or ring opening of imides moiety by spectroscopic measurements. The polyimides were useful as positive working photodegradable polymers. Especially, the positive tone image of polyimide containing a pyromellitic diimide moiety exhibited high sensitivity and resolution.

• Korean Journal of Microbiology
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• v.37 no.2
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• pp.130-136
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• 2001

The killing effects of two types(one-phase reactor and two-phase reactor) of UV-TiO$_2$photocatalytic system on the microorganisms have been studied. The UV-lamp which emits maximum 39 watts at 254 nm was prepared in these system. Three types of $TiO_2$ coating method were adopted. One type is thin film coated form on the quartz tube in the reactor and another one is surface rough coated form on the glass bead. The other one is $TiO_2$-mixed alginate bead form. UV irradiation was carried out for 1 min. In case of one phase reactor, the bactericidal efficiencies of E. coli by $TiO_2$-coated quartz tube and $TiO_2$-coated glass bead were 63.2% and 89.9%, respectively. In the air-bubbling system, the bactericidal efficiency was 95%, however, the efficiency decreased to 90.6% in the non-bubbling system. In the $TiO_2$-mixed alginate bead system, bactericidal efficiency was 86%. When $H_2O$$_2$ was treated (10, 15, 20, and 25 mg/ι) to the $TiO_2$-coated glass bead reactor, bactericidal efficiency significantly increased according to the concentration of $H_2$$O_2$. Two phase reactor showed more elevated efficiency. E. coli was more sensitive to the reaction than S. cerevisiae.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.520-525
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• 1998

The optical properties with chemical composition change in BaO- MgO-$AI_2O_3$, system activated by divalent Eu ion were investigated under 254nm ultraviolet(UV) and 147nm vacuum ultraviolet(VUV). These phosphors emitted a blue light at a dominant wavelength of $\lambda$=445nm under UV and VUV irradiations. It was found that the brightness of $BaMgAI_{14}O_{23}$ phosphor increased with Eu concentration up to 10% under UV but it showed a maximum emitting intensity at 5% Eu for VUV. The emitting intensity of blue color of $BaMgAl_{10}O_{l7}$ phosphor was higher than that of $BaMgAI_{14}O_{23}$for both excitation. A further improvement in brightness was obtained for $Ba_{o.9}Ca_{0.1}MaAl_{14}O_{23}$ and $Ba_{0.9}Sr_{0.1}MgAl_{10}O_{17}$ phosphor synthesized by the substition of $Ba^{+2}$ ion with O.lmole of $Ca^{+2}$ or $Sr^{+2}$ ions in $BaMgAl_{IO}O_{17}$: Eu phosphor.

• Analytical Science and Technology
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• v.20 no.4
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• pp.347-354
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• 2007

A simple and rapid high-performance liquid chromatography assay for the determination of residual novobiocin levels in bovine, porcine, chicken, flatfish and japanese eel muscle has been developed and validated. The separation condition for HPLC/UV was optimized with phenyl hexyl ($4.6{\times}150mm$, $5{\mu}m$) column with 10 mM monobasic sodium phosphate buffer (pH 2.5)/acetonitrile (50/50, v/v) as the mobile phase at a flow rate of 1.0 mL/min and detection wavelength was set at 254 nm. Residues were extracted from tissue by blending with methanol and lipid materials were removed with n-hexane. Then, the methanol extract was evaporated to dryness under a nitrogen stream, reconstituted in the mobile phase. Aliquot of the organic extract was decanted and filtered through $0.45{\mu}m$ syringe filter. The $20{\mu}L$ of the resulting solution was injected into the HPLC system. The calibration ranges were $0.5{\sim}5{\mu}g/g$ and calibration curves were linear with coefficients of correlation better than 0.95. The limits of quantification were $0.5{\mu}g/g$ for all muscles. The recoveries of bovine, porcine, chicken, flatfish and japaneseel muscles were 99.8%, 102.4%, 91.0%, 104.0% and 93.0%, respectively. The procedures were validated according to the CODEX guideline, determining specificity, linearity, accuracy, precision, quantitation limit and recovery.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.534-541
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• 2014

This study investigated a method to determine an efficient operating condition for the $UV/H_2O_2$ process. The OH radical scavenging factor is the most important factor to predict the removal efficiency of the target compound and determine the operating condition of the $UV/H_2O_2$ process. To rapidly and simply measure the scavenging factor, Rhodamine B (RhB) was selected as a probe compound. Its reliability was verified by comparing it with a typical probe compound (para-chlorobenzoic acid, pCBA); the difference between RhB and pCBA was only 1.1%. In a prediction test for the removal of Ibuprofen, the RhB method also shows a high reliability with an error rate of about 5% between the experimental result and the model prediction using the measured scavenging factor. In the monitoring result, the scavenging factor in the influent water of the $UV/H_2O_2$ pilot plant was changed up to 200% for about 8 months, suggesting that the required UV dose could be increased about 1.7 times to achieve 90% caffeine removal. These results show the importance of the scavenging factor measurement in the $UV/H_2O_2$ process, and the operating condition could simply be determined from the scavenging factor, absorbance, and information pertaining to the target compound.

• Elastomers and Composites
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• v.52 no.4
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• pp.287-294
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• 2017

Nanocomposites based on $SnO_2-Mn$ were synthesized by the reaction of tin (II) chloride dihydrate and manganese (II) chloride tetrahydrate at a molar ratio of 10:1 in the presence of ammonium hydroxide at $80^{\circ}C$. The $SnO_2-Mn$ nanocomposites were stirred with fullerene [$C_{60}$] in a mass ratio of 2:1 in tetrahydrofuran to prepare $SnO_2-Mn-C_{60}$ nanocomposites; these nanocomposites were obtained upon heating the mixture of $SnO_2-Mn$ nanocomposites and fullerene [$C_{60}$] in an electric furnace at $700^{\circ}C$ for 2 h. The synthesized $SnO_2-Mn-C_{60}$ nanocomposites were confirmed through various characterization methods such as X-ray diffraction and scanning electron microscopy. The photocatalytic activities of the $SnO_2-Mn-C_{60}$ nanocomposites were demonstrated by the degradation of the organic dyes BG, MB, MO, and RhB under 254 nm irradiation and evaluated using UV-Vis spectrophotometry.