• 한국결정성장학회지
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• 제24권6호
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• pp.256-260
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• 2014

본 연구는 코발트 코팅 두께에 따른 점토 표면과의 반응성을 연구하였다. 시편에서 표면으로 부터 일정한 두께로 코발트가 확산된 것을 볼 수가 있으며, 황화코발트의 도포양과 함께 청자토보다 백자토에서 확산층의 두께가 증가하였다. 백자토에 코팅된 시편은 grayish blue가 blue 색으로 변화되는 것을 알 수 있으며 $L^*$값이 51.78에서 37.61로 감소하고, 청자토에 코팅된 시편인 경우 dark olive gray에서 dark gray색으로 $L^*$값이 53.91에서 38.93로 적어지는 것을 알 수가 있다. 시편의 물성 평가는 XRD, SEM, 열팽창기, TG-DTA, UV-vis spectrophotometer와 HRDPM을 이용하였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.321-324
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• 2000

Monascus purpureus ATCC 16365에 의한 5-liter 배양기에서 pH 조절을 통하여 세포외로 이차대사물인 수용성 적색소의 생산 증가 현상 와 황색소 보다 적색소로의 대사과정을 촉진시켜 적색소의 생산성을 향상시킬수 있는지의 가능성에 대하여 실험을 수행하였다. 황색소와 적색소의 분석은 UV-Vis spectrophotometer를 이용하여 각각 385nm 와 495nm에서 측정하였다. 실험결과 곰팡이의 최대균체량과 황${\cdot}$적색소를 포함한 총 색소 생산양은 pH 8보다 pH 4.0-5.5인 산성조건에서 2배 및 4배정도 증가하였다. 적색소 및 황색소의 전구물질인 홍색소는 pH 4.0에서 많이 생성되며 또한 홍색소에서 적색소로의 대사과정도 산성 조건 하에서 촉진된다고 보고되었다. 본 실험에서도 같은 경향을 보였으며 또한, 산성 조건 하에서 특히 수용성 적색소가 곰팡이 세포 외로 유출되는 양이 증가하는 경향을 나타내었다.

• 한국재료학회지
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• 제19권12호
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• pp.657-660
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• 2009

Optical characteristics and structural changes depending on CuO content in phosphate glasses that are used in near-infrared (near-IR) filters were investigated. With phosphate glasses that contain 1-9 mol% CuO, changes in optical transmittance, optical absorption, and color coordinate were measured with a UV-VIS spectrophotometer. An XPS (X-ray photoelectron spectroscopy) analysis was performed to determine valence of copper ion that influences optical characteristics in near-IR filter glasses. Structural changes in glasses depending on CuO content were also analyzed by FT-IR (Fourier transform infrared) and Raman spectrophotometers. From the UV-VIS spectrophotometer results, strong absorption peaks at 220 & 900 nm were found and transmittance was decreased. The color coordinates of the glasses were shifted to the green color direction with CuO addition for increasing absorption of long wavelength range spectra, in spite of the amount of $Cu^{2+}$, which gives a blue color to glasses, and which was increased in XPS results. Also, structural de-polymerization of glasses with CuO addition were found by FT-IR and Raman results.

• 한국환경농학회지
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• 제40권2호
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• pp.127-133
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• 2021

BACKGROUND: Dithiocarbamte fungicides have been used in crop cultivation for diseases protection and treatment. And cultivated agricultrual products were used as feedstuff, and residual pesticides are likely to be absorbed and transferred to livestock. But the maximum residue limits (MRLs) were not established for dithiocarbate fungicides in livestock products, and thus an analysis method was developed and validated for dithiocarbamate fungicides to establish MRLs. METHODS AND RESULTS: Samples were prepared using CS₂ trap method and detected with UV/VIS spectrophotometer. Calibration line (0.1 ~ 10 ㎍/mL) was linear with r² > 0.99. For validation, the recovery tests were carried out at three fortification levels (MLOQ, 10 MLOQ and 50 MLOQ) from livestock samples (egg, milk, beef, pork, and chicken). The results for mancozeb, propineb, and thiram ranged between 76.8 to 109.6%, 79.4 to 108.8%, and 80.2 to 107.8%, respectively and % RSD (relative standard deviation) values were below 9.5%. Furthermore, inter-laboratory analysis was performed to validate the method. CONCLUSION: All values were corresponded with the criteria ranges requested by both the CODEX (CAC/GL 40-1993, 2003) and MFDS guidelines (2016). This might be used as an official analytical method for determination of dithiocarbamate fungicides at established MRLs and monitoring.

• 분석과학
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• 제6권1호
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• pp.121-129
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• 1993

란탄족 원소 분석에서 란탄족 원소 상호간의 간섭영향에서 오는 방해영향을 제거하고 정확한 분석 결과를 얻기 위해 란탄족 원소들을 이온크로마토그래피로 분리하였다. 분리된 란탄족 원소들은 PAR(4-(2-pyridylazo)-resorcinol monosodium salt)과의 포스트컬럼 착색반응을 통하여 발색한 후, UV/VIS 흡광광도법으로 520nm의 파장에서 흡광도를 측정하여 란탄족 원소들을 분석하였다. 이때 용리액은 Pyromellitic acid였고 분리순서는 Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, Lu였고, La, Ce, Pr, Nd는 pyromellitic acid로 분리되지 않으므로 옥산살을 사용하여 분리 분석하였다. Pyromellitic acid의 pH 2.99에서 중란탄족 원소들이 가장 잘 분리되었다.

• 한국재료학회지
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• 제30권6호
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• pp.279-284
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• 2020

In this work, a carbon-doped carbon nitride photocatalyst is successfully synthesized through a simple centrifugal spinning method after heat treatment. The morphology and properties of the prepared photo catalyst are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectrophotometer (UV-vis), and specific surface area. The results show that the band gap of the prepared sample, g-CN-10 is 2.1 eV, is significantly lower than that of pure carbon nitride, 2.7 eV. As the amount of cotton candy increased, the absorption capacity of the prepared catalyst for visible light is significantly enhanced. In addition, the degradation efficiency of Rhodamine B (RhB) by sample g-CN-10 is 98.8 % over 2 h, which is twice that value of pure carbon nitride. The enhancement of photocatalytic ability is attributed to the increase of specific surface area after the carbon doping modifies carbon nitride. A possible photocatalytic degradation mechanism of carbon-doped carbon nitride is also suggested.

• 한국의류산업학회지
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• 제8권4호
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• pp.465-470
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• 2006

Walnut hull is a by-product from the Walnut tree, used as natural dyestuff from ancient times. This study was done to examine the effects of extractive conditions on the properties of walnut hull extracts for making efficient use of the walnut hull as a natural colorant. Aqueous extracts of walnut hull were prepared at various extractive concentration, temperature and time. Then they were characterized using UV-Vis. Spectrophotometer, FT-IR Spectrometer, Prep Liquid Chromatography, and Energy dispersive X-ray spectrometer. The aqueous extracts have two absorbency peaks of UV-Vis. Spectrum, shoulder type peak in the range of 270-280 nm and broad type band around 420 nm. Intensity of absorbency is increased with increase of extraction concentration and time. However, Boiling temperature extraction method showed the most efficiency of all. Intensity of absorbency is also affected by extraction pH. The Prep LC examined two kinds of isolated colorant with different molecular weight. FT-IR spectra of hull extracts showed an absorption band around $3400cm^{-1}$, the peaks at $1700-1600cm^{-1}$, which are characteristic of aromatic compounds with unsaturated ketone and benzene ring. It showed that the extraction contained some mineral ions, such as K, Ca, Si, Mg.

• 대한화학회지
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• 제41권6호
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• pp.299-303
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• 1997

4-치환 Phenyl ethyl benzylphosphonate의 알칼리 가수분해 반응에 대한 속도 상수($k_{OH}$)를 UV-Vis 분광 광도계로서 결정하였다. 활성화 엔트로피(${\Delta}S^{\neq}$)값은 큰 음의 값을 가졌으며 이 결과는 활성화 엔트로피가 양의 값이나 작은 음의 값으로 기대되는 해리 반응(EA)과 일치하지 않았고 좋은 Hammett 상관 관계식으로부터 속도결정단계에서 이탈기에 의해 음의 전하가 거의 발생하지 않는 회합성(AE) 메커니즘이 일어남을 강력히 암시하고 있다. 반응속도론적 연구 결과에 의하면 4-치환 Phenyl ethyl benzylphosphonate의 가수분해 반응은 해리 메커니즘으로 진행되지 않음을 알 수 있었다.

• 청정기술
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• 제12권3호
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• pp.145-150
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• 2006

수용액을 전기분해하면 반응성 유기화합물을 가수분해할 수 있는 수산화이온 및 수소이온을 얻을 뿐만 아니라 차아염소산이온과 같이 화합물을 산화시킬 수 있는 산화제도 얻을 수 있다. 자체 제작한 장치를 이용하여 염료 전기분해를 시도하였고, HPLC 및 UV-VIS 분광광도계를 이용하여 분해정도를 분석하였다. 전기분해장치를 이용하면 높은 반응속도와 저렴한 유지비용으로 염료 분해가 가능하며, 반응도중 소모되는 시약 보충 및 반응 후 부산물 처리 등의 과정이 수월하다. 다양한 염료에 대하여 분해시간을 비교하였고, 수처리 분야 응용에 대하여 토의하였다.

• Elastomers and Composites
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• 제51권3호
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• pp.240-249
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• 2016

$BiVO_4$ nanomaterial was synthesized from bismuth (III) nitrate pentahydrate [$Bi(NO_3)_3{\cdot}5H_2O$] and ammonium vanadate (V) [$NH_4VO_3$]. The $BiVO_4$-graphene nanocomposite was fabricated by calcining the $BiVO_4$ nanomaterial and graphene under an oxygen-free atmosphere at $700^{\circ}C$. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize structural and morphological properties of samples. The catalytic activity of the $BiVO_4$-graphene nanocomposite was studied for the reduction of 4-nitrophenol, 3-nitrophenol and 2-nitrophenol by sodium borohydride [$NaBH_4$]. The photocatalytic activity of the $BiVO_4$-graphene nanocomposite was demonstrated by the degradation of organic dyes like BG, MB, MO and RhB under irradiation at 365 nm. The catalytic and photocatalytic activity were studied by UV-vis spectrophotometry.