• 한국산업보건학회지
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• 제23권4호
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• pp.341-347
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• 2013

Objectives: The aim of this study is to investigate the differences in airborne TDI concentrations based on the filter collection method and liquid collection method and to compare airborne TDIs concentrations by sampling method change when using the filter collection method in the spray-painting process. Methods: For the sample measurement, the filter collection method(OSHA#42) and liquid collection method(NIOSH#5522) were used; for the sampling method, the full-period single sampling and full-period consecutive sampling methods were used. The samples were collected in spray-painting and drying process locations. Results: In all samples collected from the spray-painting and drying process locations through the filter collection and liquid collection methods, greater amounts of 2,6-TDI than 2,4-TDI were detected. When the TDI collection concentrations based on the sampling methods were compared, the concentrations of 2,4-TDI and 2,6-TDI collected by the consecutive sampling method were higher than the concentrations of 2,4-TDI and 2,6-TDI collected by the single sampling method for both the filter collection method and liquid collection method used in the spray-painting process. These differences were statistically significant. Conclusions: When TDI collection concentrations based on the sample measurement methods were compared, the concentration of 2,4-TDI and 2,6-TDI collected through the liquid collection method were higher than the concentrations of 2,4-TDI and 2,6-TDI collected by the filter collection method, and the differences were statistically significant. In the drying process, no difference was shown in the collection concentrations of 2,4-TDI and 2,6-TDI with the two measurement methods.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1997년도 추계총회 및 학술발표회 논문집
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• pp.32-35
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• 1997

Aggregation states ans electro-optic properties of a binary mixture by mixing a side chain type liquid crystalline polymer(LCP) and a low molecular weight liquid crystal(LMLC) have been studied. Side chain liquid crystalline polysiloxanes were synthesized from allyl bromide, p-hydroxy benzoic acid, p-cyanophenol, p-methoxyphenol and polysiloxanes. Low molecular weight liquid crystals were synthesized from allyl bromide, p-hydroxy benzoic acid and 4-cyano 4'-hydroxy biphenyl. And then, their properties were compared with blended liquid crystals. The thermal properties of the blended liquid crystals were evaluated using differential scanning calorimetry. The phase behavior of blended sample with temperature were also observed polarized microscope with hot stage. Thus, it seemed to us that a study of LC polysiloxanes with LMLC would be useful, especially in view of the fact that, systematic investigations have been carried out on the effects of changes in LCP/LMLC binary system on the properties of this relatively new type of liquid crystal.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.269-272
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• 2005

Due to the high density and heating value, liquid fuel is attractive for ramjet propulsion system. Liquid fuel requires time to evaporation and mix with incoming air before ignition; insufficient evaporation and mixing result in low combustion efficiency and instability. So the numerical studies are conducted to investigate the spray and combustion characteristics of a liquid-fueled dump type Integrated Rocket Ramjet combustor. The governing equations are solved by means of a finite-volume using time derivative preconditioning method for chemical reacting flow. The liquid phase is treated by solving Lagrangian equations of motion and transport for the life histories of a statistically significant sample of individual droplets.

• 분석과학
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• 제12권5호
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• pp.428-435
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• 1999

액체섬광계수기를 이용한 수용액시료 중의 미량의 Rn-222 및 Ra-226 농도 측정을 위한 분석방법을 확립하였다. 라돈 분석을 위해 자이렌계열 섬광용액(xylene-based cocktail) 12 mL를 사용하여 물 시료(10mL)내 라돈을 선택적으로 용매 추출하였다. 추출된 라돈을 측정용기 내에서 딸핵종과의 방사 평형을 위해 3시간동안 방치한 후 저준위 액체섬광계수기를 이용하여 계측하였다. Ra-226 분석을 위해서는 화학적 분리과정을 거친 후 자이렌 계열 섬광용액이 포함된 측정용기 내에서 일정 기간동안의 방사평형을 거쳐 생성된 Rn-222 및 알파선 딸핵종을 계측하였다. Rn-222 및 그의 알파선 딸핵종의 계측을 위한 최적 파형분석(PSA) 준위는 바탕시료에 대한 최대 효율값(Figure of Merit)을 조사하여 설정하였다. PSA 준위 100에서 폴리에틸렌 용기와 자이렌계열 섬광용액을 사용하여 준비된 시료를 200분 동안 계측하였을 때 얻어진 검출하한값(MDA)은 알파선의 총 피크영역에서 0.14 Bq/L(3.78 pCi)이었고, Po-214 만의 피크영역에서는 0.06 Bq/L(1.63 pCi)이었다. 섬광용액에 대한 시료의 부피비와 시료용기의 취급 및 시료용기를 통한 라돈기체의 손실등이 계측치에 미치는 영향을 고찰하였다.

• 한국토양비료학회지
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• 제34권3호
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• pp.153-157
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• 2001

To evaluate the effect of liquid pig manure application, the growth and yield of rice and the quality of infiltration water were investigated with application of different amounts of liquid manure. At this study, liquid pig manure was treated with 100, 200, 300 and 400% of recommending nitrogen fertilizer level, respectively. Liquid manure with application rate more than 200% of recommending N fertilizer level (11kg) caused to increase of plant height and number of tiller at panicle formation stage, but it caused the plant disease and pest and plant lodging. In those treatment, number of panicles per hill and number of spikelets per panicle were increased, but yield of rice was less than chemical fertilizer treatment due to low rate of ripeness and 1,000 grain weight. $NO_3-N$ concentration in infiltration water sample collected at 90 cm of soil depth was increased with increasing application amount of liquid manure. With liquid manure application more than 200% of recommending N fertilizer level, it affected negatively on yield and environment such as groundwater quality.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1021-1021
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• 2001

Sample presentation, which means how to set samples to an NIR instrument, is very important in Near Infrared (NIR) Spectroscopy. When sample presentation is not suitable for the samples that you use, very good spectra can not be obtained even if you use a sophisticated NIR instrument. In my presentation, various NIR sample presentations for agricultural products such as intact fruits, single grains, vegetable juice and the others will be explained. In case of peaches with thin peel, the fiber optics of Interactance can be used. However, the fiber optics are not suitable for oranges with relatively thick peel. In this case, transmittance method is useful. As for a small sample such as single grains, a specially designed cell is needed. The cell in transmittance mode has been developed and then applied to single kernels of rice and soybean. In this case we also used the fiber optics. As regards liquid type of sample, a cuvette cell made of quartz in transmittance mode is popular. However, it is time-consuming to wash and dry it. In order to compensate this disadvantage the sample presentation using normal test tubes as sample cells have been developed and applied to milk, rumen juice and urine of a milking cow. An individual test tube can be used for each sample if you use the calibration equation with sample cell compensation. The test tube cell has also been applied to spinach juice for determination of undesirable constituents. It is concluded that sample presentation is most important for NIR Spectroscopy.

• 한국식품위생안전성학회지
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• 제5권4호
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• pp.213-217
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• 1990

커피, 홍차, 녹차중의 카페인 함량을 간단하고 신속하게 정량하는 방법을 검토하였다. 역상계 액체크로마토그래피에 의한 카페인 정량은 메타놀-초산-물(20 : 1 : 79)을 이동상으로 하여 ${\mu}-Bondapak$ C18 컬럼하에서 이루어졌다. 카페인의 검출에는 UV검출기를 사용하여 280 mm에서 행하였다. Sep-Pak alumina A 카트리지를 이용한 간단한 전처리를 통해 효과적으로 카페인의 추출 및 clean-up를 행하였다. 카페인의 첨가 회수율은 95.2~101.3%이었고 분석의 재현성은 상대표준 편차로서 0.10~0.62%이었으며 검출한계는 $0.1;\mu\textrm{g}$/ml이었다.

• 한국환경농학회지
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• 제29권3호
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• pp.247-256
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• 2010

A high-performance liquid chromatographic (HPLC) method was developed to determine buprofezin residues in hulled rice and fruits. The buprofezin residue was extracted with acetone and the extract was stepwise purified by liquid-liquid partition and Florisil column chromatography. For rice samples, acetonitrile/n-hexane partition was additionally employed to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate buprofezin from sample co-extractives, as detected by ultraviolet absorption at 250 nm. Recovery experiment at the limit of quantitation validated that the proposed method could evidently determine the buprofezin residue at the level of 0.02 mg/kg. Mean recoveries from hulled rice, apple, pear, and persimmon samples fortified at three tenfold levels were in the range of 80.8~85.2%, 89.1~98.4%, 88.8~95.7% and 90.8~96.2%, respectively. Relative standard deviations of the analytical method were all less than 5%, irrespective of sample types. A selected-ion monitoring LC/mass spectrometry with positive electrospray ionization was also provided to sensitively confirm the suspected residue.

• 한국동물위생학회지
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• 제41권2호
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• pp.125-131
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• 2018

This study investigated the effects of the alkaline detergent and acid rinse used for cleaning milking machines on the rubber composition of the newly-developed teat cup liners. The samples prepared for use in the clean-in-place process were analyzed by ultraviolet spectrophotometer, ion chromatography and liquid chromatography. In the absorption spectrum of the first sample solution, the form of absorbance or absorption peak was largely different, compared to the absorption spectrum of alkaline detergent alone, but in the absorption spectra of the second and third sample solutions, the absorbance decreased, which was similar to the absorption spectrum in the pure acid detergent. In the ion chromatogram, two main peaks only, which might be shown by the pure alkaline detergent alone, were measured. In the liquid chromatograms, however, new peaks were observed in addition to the two main peaks caused by the pure alkaline detergent alone, which suggested that various molecular materials were created or eluted from the liner by the reaction with the alkaline detergent, but when washed with the acid detergent, any ion species were not produced. Therefore, we propose that an acid rinse should be applied, after cleaning the milking machine with the alkaline detergent.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3228-3232
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• 2010

Malachite green (MG) has been used world-widely in aquaculture as a parasiticide or fungicide. Although MG performed successfully, it has not been permitted for use in aquaculture from European Union, USA, and Canada because of its carcinogenicity and mutagenicity. We developed a sensitive and specific method to determine MG and its principal metabolite, leucomalachite green (LMG), respectively by isotope dilution liquid chromatography mass spectrometry (ID-LC/MS). To enhance the extraction recovery of MG and LMG from fish tissue, an additional step, saponification, was introduced in sample preparation process to remove fat in sample extract, which hampered the performance of SPE columns. The residue of MG and LMG in fish was analyzed using liquid chromatography mass spectrometry in the selected ion monitoring (SIM) mode by monitoring at m/z 329 and 334 for MG and $d_5$-MG and at m/z 331 and 337 for LMG and $^{13}C_6$-LMG, respectively. This method was validated by comparing with the value of the reference material provided by Laboratory Government Chemistry (LGC). The results agreed within the measurement uncertainty and the accuracy was much improved than the provided reference value by LGC.