• 분석과학
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• 제8권1호
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• pp.47-53
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• 1995

수용액에서 $TPB^-$와 $PG^+$의 회합을 흡수 및 형광분광법으로 연구하였다. 1, 4-dioxane을 PG-TPB 수용액에 첨가하면 순수한 물보다 용매의 소수성이 증가되어 $PG^+$와 $TPB^-$ 사이의 회합체가 해리되었고, $PG^+$만의 수용액보다 $PG^+$ 단위체의 농도가 더 크게 나타났다. 물을 제외한 모든 유기 용매에서 회합은 관찰되지 않았고, 최대 흡수는 ${\pi}^*$ 척도와 $(n^2-1)/(2n^2+1)$ 함수를 사용하였을 때가 비교적 좋은 직선 관계를 주었다. 그러나 알코올의 경우는 ${\pi}^*$ 척도를 사용하였을 때가 더 훌륭한 직선 관계를 주었다.

• 한국분말재료학회지
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• 제24권5호
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• pp.395-399
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• 2017

Solder paste is widely used as a conductive adhesive in the electronics industry. In this paper, nano and microsized mixed lead-free solder powder (Sn-Ag-Cu) is used to manufacture solder paste. The purpose of this paper is to improve the storage stability using different types of solvents that are used in fabricating the solder paste. If a solvent of sole acetate is used, the nano sized solder powder and organic acid react and form a Sn-Ag-Cu malonate. These formed malonates create fatty acid soaps. The fatty acid soaps absorb the solvents and while the viscosity of the solder paste rises, the storage stability and reliability decrease. When ethylene glycol, a dihydric alcohol, is used the fatty acid soaps and ethylene glycol react, preventing the further creation of the fatty acid soaps. The prevention of gelation results in an improvement in the solder paste storage ability.

• Archives of Pharmacal Research
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• 제19권5호
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• pp.396-399
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• 1996

High-performance liquid chromatographic method with UV detecction was developed for the determination of theophylline and its metabolites in human urine using ${beta}$-hydroxyethyl theophylline$({beta} -HET)$ as an internal standard. For extraction of urine sample, quality control sample and xanthine-free blank urine were mixed with decylamine (ion-paring reagent) and ${beta}$-HET. After saturation with ammonium sulfate, the mixture was then extracted with organic solvent at pH values of 4.0-4.5. All separations were performed with ion-pair chromatography using decylamine as an ion-pairing reagent and 3mM sodium acetate buffered mobile phase (pH 4.0) containing 1% (v/v) acetonitrile and 0.75 mM decylamine. The detection limits of theophylline, 1, 3-DMU, 1-MU, 3-MX and 1-MX in human urine were 0.17, 0.17, 0.39, 0.19 and 0.19 ${\mu}g$/ml, based on a signal-to-noise ratios of 3.0. The mean intraday coefficients of variation (C.V.s) of each compound on nine replicates were lower than 2.0%, while mean interday C.V.s on three days were lower than 1.6%. All separations were finished within 40miutes.

• 한국자원식물학회지
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• 제21권6호
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• pp.435-439
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• 2008

Due to the fact that tocopherols and tocotrienols have antioxidant and anticancer properties, the commercial utilization of unsaponifiable fractions in rice bran is increasing. These nutraceutical compounds, however, are fairly unstable and readily break down when exposed to oxygen or lighting conditions. To compare the relative sensitivity of vit E isomers to heat and oxygen, concentrated unsaponifiable fractions extracted from crude rice bran oil were exposed to various temperature, oxygen (nitrogen-balanced), and bathing solvent conditions and resultant concentration changes in ${\alpha}$- and ${\gamma}$-tocopherols (T) and tocotrienols (T3) were evaluated. Each isomer exhibited different heat stability. Among them, ${\alpha}$-T3 degraded more rapidly compared to other vit E isomers while ${\alpha}$-T was the most stable isomer. Oxygen level also showed significant impact on each isomer's stability where severe reductions of ${\gamma}$-T (by 20%) and ${\gamma}$-T3 (by 29%) were observed under 2% oxygen conditions, while under 0% oxygen conditions no degradation could be observed even after exposure to $95^{\circ}C$ for 4 hours. When various blending solvents were mixed with concentrated unsaponifiable fractions, organic solvents such as isooctane and hexane were more effective in maintaining the stability of ${\gamma}$- T3 compared to edible oils, among which com oil was more efficient than soybean and rice bran oils.

• 한국수소및신에너지학회논문집
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• 제13권3호
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• pp.224-232
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• 2002

CdS-$TiO_2$ nano-composite sol was prepared by the sol-gel method in organic solvents at room temperature and further hydrothermal treatment at various temperatures to control the physical properties of the primary particles. Again, CdS-$TiO_2$ composite particulate films were made by casting CdS-$TiO_2$ sols onto $F:SnO_2$ conducting glass and then heat-treatment at $400^{\circ}C$. Physical properties of these 61ms were further controlled by the surface treatment with $TiCl_4$, aqueous solution. The photo currents and hydrogen production rates measured under the experimental conditions varied according to the $CdS/[CdS+TiO_2]$ mole ratio and the mixed-sol preparation method. For $CdS-TiO_2$ composite sols prepared in IPA, CdS particles were homogeneously surrounded by $TiO_2$ particles. Also, the surface treatment with $TiCl_4$ aqueous solution caused a considerable improvement in the photocatalytic activity, probably as a result of close contacts between the primary particles by the etching effect of $TiCl_4$. It was found that the photoelectrochemical performance of these particulate films could be effectively enhanced by this approach.

• 마이크로전자및패키징학회지
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• 제13권1호통권38호
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• pp.37-42
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• 2006

유기 박막트랜지스터(OTFTs)제작에서 PVP-게이트 절연막의 형성과 처리가 소자성능에 미치는 영향을 조사하였다. 유기 게이트 용액의 제조에서는 polyvinyl 계열의 PVP(poly-4-vinylphenol)를 용질로, PGMEA (propylene glycol monomethyl ether acetate)를 용매로 사용하였다. 또한 열경화성 수지인 poly(melamine-co-formaldehyde)를 경화제로 사용하여 유기 절연막의 cross-link를 시도하였다. MIM 시료의 전기적 절연 특성을 측정한 결과, PVP-기반 유기 절연막은 용액의 제조에서 PGMEA에 대한 PVP와 poly (melamine-co-formaldehyde)의 농도를 증가시킬수록 낮은 누설전류 특성을 나타내었다. OTFT 제작에서는 PGMEA에 대해 PVP를 20 wt%로 섞은 PVP(20 wt%) copolymer와 5 wt%와 10 wt%의 poly(melamine-co-formaldehyde)를 경화제로 추가한 cross-linked PVP(20 wt%)를 게이트 유전 재료로 사용하였다. 제작된 트랜지스터들에서 전계효과 이동도는 5 wt % cross-linked PVP(20 wt%) 소자에서 $0.31cm^2/Vs$로, 그리고 전류 점멸비는 10 wt% cross-linked PVP(20 wt%) 소자에서 $1.92{\times}10^5$으로 가장 높게 나타났다.

• 자원리싸이클링
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• 제27권3호
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• pp.8-15
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• 2018

Nd-Fe-B 폐 영구자석으로부터 회수한 염화희토류용액을 PC88A에 의한 경희토류(Pr, Nd)/중희토류(Tb, Dy) 분리정제에 대한 용매추출 연구를 진행하였다. 회분식 실험 단계에서 추출제(PC88A) 농도 0.5 M, 추출 후 평형 pH는 0.8~1.0(feed의 초기 pH 1.3), 세정액(HCl)의 농도는 0.1 M, 탈거액(HCl)의 농도는 2 M 이상일 때 분리 효율이 좋은 것을 확인하였다. 이 결과값을 혼합침강조에 적용하여 초기 조건에서 운용 조건을 변화시키면서 180시간 운용하여 3N급의 경희토류(Pr, Nd)/중희토류(Tb, Dy)금속 이온으로 분리정제 후 회수하였다.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2006년도 춘계임시총회 및 제27회 학술발표대회
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• pp.90-94
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• 2006

액정(LCD)과 반도체 제조공정에서 발생하는 인산, 질산, 초산, Al, Mo 등이 혼재하고 있는 인산계 혼산폐액을 액정제조공정에서 사용할 수 있는 고순도 에칭액으로 재활용하기 위해서 용매추출법, 진공 증발법, 확산투석법 및 이온교환법의 각각의 기술적 특성을 살린 혼합 처리공정을 이용하여 고순도 인산 회수 기술을 확립하고 상용화 시스템을 개발하고자 하였다. 시험 결과 진공증발에 의해 질산과 초산을 100% 제거할 수 있었고, TOP를 사용한 용매추출에서도 추출 4단, 탈거 6단, 상비 1/3으로 완벽하게 제거할 수 있었다. 이온교환의 전단계로 적용한 확산투석에서 Al 97%, Mo 75% 제거할 수 있었고 이온교환공정에서 Al 및 Mo를 각각 1ppm 이하로 정제할 수 있었다.

• Journal of Korean Dental Science
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• 제5권1호
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• pp.7-12
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• 2012

Purpose: To examine the antibacterial effectiveness of silver nanoparticles (SNP) mixed with commercial orthodontic adhesives. Materials and Methods: SNP was prepared by dissolving silver perchlorate in an organic solvent and reducing it with ultraviolet radiation. SNP was then mixed with four commercial orthodontic adhesives (Light Bond, Blugloo, Transbond XT, and Fuji Ortho LC) (0.05 wt %), which were then formed into disc-shape specimens ($8.0mm{\times}3.0mm$). Commercial orthodontic adhesives containing no SNP were used as the control groups. Specimens of the four experimental and four control groups were incubated with streptococcus mutans and the medium turbidity was assessed at 3, 6, 9, 12, and 24 hours after incubation. The agar diffusion test was also performed to examine the growth inhibition zone of these groups. The data were statistically analyzed using a Wilcoxon rank sum test and t-test with a Bonferroni's correction (P<0.05). Result: The SNP containing groups had a superior antibacterial effect compared to the control groups. In the agar diffusion test, the control groups without SNP did not produce an inhibition zone, whereas the SNP containing groups showed inhibition zone of 10~13 mm. Conclusion: The incorporation of SNP into orthodontic adhesives can inhibit cariogenic bacterial growth.

• 한국의학물리학회지:의학물리
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• 제28권4호
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• pp.226-231
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• 2017

The aim is to investigate the spectra responsibilities of QD (Quantum Dot) for the innovation of new dosimetry application for therapeutic Megavoltage X-ray range. The unique electrical and optical properties of QD are expected to make it a good sensing material for dosimeter. This study shows the spectra responsibility of toluene based ZnCd QD and PPO (2.5-diphenyloxazol) mixed liquid scintillator. The QDs of 4 sizes corresponding to an emission wavelength (ZnCdSe/ZnS:$440{\pm}5nm$, ZnCdSeS:470, 500, $570{\pm}5nm$) were utilized. A liquid scintillator for control sample was made of toluene, PPO. The Composition of QD loaded scintillators are about 99 wt% Toluene as solvent, 1 wt% of PPO as primary scintillator and 0.05, 0.1, 0.2 and 0.4 wt% of QDs as solute. For the spectra responsibility of QD scintillation, they were irradiated for 30 second with 6 MV beam from a LINAC ($Infinity^{TM}$, Elekta). With the guidance of 1.0 mm core diameter optical fiber, scintillation spectrums were measured by a compact CCD spectrometer which could measure 200~1,000 nm wavelength range (CCS200, Thorlabs). We measured the spectra responsibilities of QD loaded organic liquid scintillators in two scintillation mechanisms. First was the direct transfer and second was using wave shifter. The emission peaks from the direct transfer were measured to be much smaller luminescent intensity than based on the wavelength shift from the PPO to QDs. The emission peak was shifted from PPO emission wavelength 380 nm to each emission wavelength of loaded QD. In both mechanisms, 500 nm QD loaded samples were observed to radiate in the highest luminescence intensity. We observed the spectra responsibility of QD doped toluene based liquid scintillator in order to innovate QD dosimetry applicator. The liquid scintillator loading 0.2 wt% of 500 nm emission wavelength QD has most superior responsibility at 6 MV photon beam. In this study we observed the spectra responsibilities for therapeutic X-ray range. It would be the first step of innovating new radiation dosimetric methods for radiation treatment.