• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1009-1011
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• 2004

In the present work a very simple, sensitive and selective spectrophotometric method for the determination of nitrite in micellar media is described. The method is based on the color reaction of nitrite with p-nitroaniline in the presence of diphenylamine in acid media. In order to remove the extraction step, Triton X-100, a non-ionic surfactant was used as micellar media. The optimum reaction conditions such as acid concentration, reagents concentration and effect of time have been studied and the analytical characteristics of the method such as limit of detection, linear range and molar absorptivity have been obtained. The interference of some anions and cations was also tested. The method was applied to the determination of nitrite in real samples.

• 대한화학회지
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• 제45권1호
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• pp.45-50
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• 2001

흡수분광분석장치와 반사분광분석장치가 결합된 형태의 복합분광분석장치를 제작하여 흡수분광분석과 반사분광분석의 성능을 서로 비교하였다. $Cu^{2+}$이온표준용액과 $Co^{2+}$이온표준용액들을 사용한 실험결과에 의하면, 분석대상성분의 농도가 너무 묽은 경우나 분석대상성분의 몰흡광계수가 충분히 크지 않은 경우와 같이 기존의 흡수분광분석으로는 정량분석이 힘든 시료용액에 대한 분광분석에 용이하게 적용될 수 있다는 사실을 확인하였다.

• 한국레이저가공학회지
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• 제6권1호
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• pp.9-16
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• 2003

Micromachining using the DPSS 3rd Harmonic Laser (355nm) has outstanding advantages as a UV source in comparison with Excimer lasers in various aspects such as maintenance cost, maskless machining, high repetition rate and so on. It also has the greater absorptivity of many materials in contrast to other IR sources. In this paper, the process for micro-drilling of blind hole in Cu/PI/Cu substrate with the DPSS UV laser and the scanning device is investigated by the experimental methods. It is known that there is a large gap between the ablation threshold of copper and that of PI. We use the Archimedes spiral path for the blind hole with different energy densities to ablate the different material. Finally, the blind via hole of diameter 100$\mu\textrm{m}$ and 50$\mu\textrm{m}$ was drilled.

• 분석과학
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• 제28권2호
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• pp.112-116
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• 2015

Extraction of quaternary ammonium compounds (choline and betaine) from plant samples (spinach) using ion exchange resin (AG1, OH⁻ form) is a very simple and inexpensive approach. However, it is very hard to determine amounts of choline and betaine simultaneously using high-performance liquid chromatography-ultraviolet (HPLC-UV) detection. Unlike choline, betaine has low molar absorptivity in UV-visible (UV-Vis) region, which makes it difficult to carry out UV-Vis detection of betaine. The mixture of quaternary ammonium compounds (choline and betaine) was derivatized using 2-bromo acetophenone as a derivatizing agent. As a result, choline did not react with the derivatizing agent, whereas betaine formed a betaine derivative. This betaine derivative exhibited detectable UV absorption with baseline separation between choline and the betaine derivative. Thus, with this method, choline and betaine can be determined simultaneously by using the HPLCUV method through one-step derivatization, which is an easy, sensitive, and reliable method.

• 한국염색가공학회지
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• 제10권5호
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• pp.56-62
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• 1998

In the prior study, the dyeing behaviors of Milling Cyanine 5R on silk fiber in aqueous dyeing liquor including small amount of organic compounds were investigated. The most effective compound was acetophenone which increased dye uptake as well as dyeing rate. In this study, the role of the acetophenone in dyeing of silk with Milling Cyanine 5R was studied. By addition of acetophenone into the dye solution, the molar absorptivity of Milling Cyanine 5R increased, and the wavelength of maximum absorption was shifted to longer wavelength, namely bathochromic shifted. This shows that the acetophenone prevents the dye to aggregate, and increases the number of monomeric dye molecule relative to the dye solution without acetophenone. This fact was also confirmed by the increase of the permeation rate of the dye through cellulose semipermeable membrane from the dye solution including the acetophenone. From these results, the acetophenone acts as a prohibitor of dye aggregation, increases the number of monomeric dye molecules even at relatively low temperature, and makes the dyes penetrate into the fiber easier.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1493-1498
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• 2007

Silicon Nitride ($Si_3N_4$), which is widely used in a variety of applications, is hard-to-machine due to its high hardness. At high temperature (e.g. above $1000^{\circ}C$), however, the machinability can be greatly improved. In this work, we used a $CO_2$ laser with a high absorptivity to $Si_3N_4$ of 0.9 to preheat the surface of a rothting $Si_3N_4$ rod. Preheating and turning of $Si_3N_4$ was executed at the same time. The result of machining was MRR of $8.0mm^3/s$ that is four times faster than normal grinding. Continuous chip formation was observed by a microscope.

• 한국인쇄학회지
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• 제22권2호
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• pp.139-150
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• 2004

Development of the paper coating technologies to prevent print mottle is needed to obtain high quality printing. Printing mottle is recognized as the most common printing problems in using coated paper and which is one of the most difficult problems to solve in offset printing. Print mottle is one of the most important quality properties of printed products and manufacturers strive to improve the paper surface to gain higher and more even print mottle. The prevention of printed mottle requires of coating color formation, especially the minimum of binder migration. The results the uniformity of liquid absorption by paper at very short contact time between paper and testing printing liquids.

• Journal of Pharmaceutical Investigation
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• 제11권3호
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• pp.1-13
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• 1981

A new application of monoacidic dye is reported for the determination of pipethanate hydrochloride(PTH). The method is based on solvent extraction into chloroform of an ion-pair compound formed between methyl orange(MO) and PTH. PTH is determined by measuring absorbance of the extracts over the range of $2.0{\sim}12.0{\mu}g/ml$ at 420nm. Best accuracy can be obtained for solutions containing $3.0{\sim}8.0{\mu}g/ml$. The color was stable for at least 5 days. The molar absorptivity was $2.88\;{\times}\;10^4\;l,\;mol^{-1},\;cm^{-1}$. Molar ratio and continuous variation plots have a maximum at 0.5 mol fraction of MO, indicating a 1 : 1 MO-PTH ratio.

• ETRI Journal
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• 제34권1호
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• pp.126-129
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• 2012

An ultra-thin hexagonal microwave metamaterial absorber is described. It can absorb any polarized transverse electromagnetic wave because of its hexagonal shape. In spite of its very thin structure, almost $0.028{\lambda}g$, the absorber achieved 99% absorptivity at 11.35 GHz in experimental results because of the increased coupling losses, showing good agreement with simulation results. In addition, this high absorbance is unchanged for any polarized waves with the same frequency.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.443-446
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• 2005

Recently, according to increase use of concrete which is the main material of construction, the natural aggregate of good quality is more and more decreased. Most of all, among the concrete materials, the development of alternation materials of sand is urgently needed. In this study, investigating the production equipment and the sample of crushed sand company and analyzing properties of sand, manufactured mortar by the KS to use crushed sand as the fine aggregate of concrete material. The experiment result is as follows. 1. The density, an absorptivity, and the amount of 0.08mm passage ratio of crushed sand, and the mortar used crushed sand satisfied KS. The mechanical results is similar to sea sand. 2. The crushed sand which used impact crusher instead of cone crusher for 3rd or 4th crusher was similar properties to sea sand, so it is judged that impact crusher has high effect of particle shape improvement of crushed sand.