• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1189-1193
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• 1998

The determination of total paraffin, naphthene, and aromatic (PNA) contents in naphtha samples, which were directly obtained from actual refining process, has been studied using near-infrared (NIR) spectroscopy. Each of the total PNA concentrations in naphtha has been successfully analyzed using NIR spectroscopy. Partial least squares (PLS) regression method has been utilized to quantify the total PNA contents in naphtha from the NIR spectral bands. The NIR calibration results showed an excellent correlation with those of conventional gas chromatography (GC). Due to its rapidity and accuracy, NIR spectroscopy is appeared as a new analytical technique which can be substituted for the conventional GC method for the quantitative analysis of petrochemical products including naphtha.

• Korean Journal of Environmental Agriculture
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• v.25 no.4
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• pp.339-345
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• 2006

Accumulation of nitrate in green vegetables is undesirable due to potential risks to human health. Lettuce was cultivated in pots under greenhouse conditions with compost applications of 2,000 and 4,000 kg/10a, and the growth and nitrate accumulation of lettuce were compared with those found in the lettuce cultivated with chemical fertilizers of recommended levels. Content of $NH_4-N$ in the soils of compost applications were much lower than those found in the soil of chemical fertilizer application. Two weeks after lettuce transplant $NH_4-N$ was not found in the soils of compost applications, and in the soils of chemical fertilizers application $NH_4-N$ was not found three weeks after lettuce transplant. One week after lettuce transplant content of $NO_3-N$ was much higher in the soils of compost applications, and the contents were rapidly decreased. While, the content of $NO_3-N$ in the soil of chemical fertilizers application was rapidly increased due to the nitrification of $NH_4$ released from the applied urea. At the time of harvest contents of $NO_3-N$ in the soils of compost applications were less than 1.4 mg/kg, but in the soil of chemical fertilizers application the content of $NO_3-N$ was 54.2 mg/kg. Contents of $NH_4$ in lettuce were about 20 mg/kg FW and were not much different among the treatments. However, contents of $NO_3$ in lettuce were significantly different between the treatments of chemical fertilizer and compost. There were significant differences in fresh and dry weights, and growth of lettuce in the compost treatment of 4,000 kg/10a was highest among the treatments. These results indicate that the cultivation with compost only as N source can produce higher yield of lettuce and significantly reduce nitrate accumulation as compared to the conventional cultivation with chemical fertilizers.

• Proceedings of the Korea Contents Association Conference
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• 2014.06a
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• pp.203-204
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• 2014

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.585-585
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• 2005

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.897-898
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• 2005

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.452-457
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• 2013

To obtain the useful data related to optimum nutrient management technique for pesticides-free jujube cultivation, nutrient contents of jujube leaves and fruits and the selected chemical properties of jujube orchard soils were investigated at 9 different orchards with pesticides-free cultivation in Boeun, Chungbuk, Korea. Soil and jujube leaf samples were collected from the different orchards in July and October, and jujube fruit samples were taken in October, 2012. Soil available $P_2O_5$ contents in the optimum level for jujube cultivation were 11% and 33% of total samples in July and October, respectively, but 56% of total samples was higher than the optimum level in both July and October. Exchangeable K and Ca ion contents were 44% and 67% of total samples, respectively, in both July and October, whereas exchangeable Mg ion content was 100% and 56% of total samples in July and October, respectively. Nutrient contents in jujube leaves were higher than those in fresh fruits. In addition, total nitrate, potassium and magnesium contents in the jujube leaves were higher in the samples collected in July than in October.

• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.66-76
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• 2004

This study is to compare and analyse the high school chemistry curriculum in Korea and Japan from the viewpoint of the structure, objectives, contents, teaching-learning method, and assessment plans. From the comparative analysis, we found some common and different aspects. The suggestive ideas which is useful for study of Korean science curriculum were deduced, such as more expansion of selective subjects and enhancing the guidance, more flexible teaching methods, enhancing the individualized instruction plans suitable to each student's condition, careful selection of educational contents and enhancing the base and foundation, and transition period.

• Elastomers and Composites
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• v.52 no.3
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• pp.201-210
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• 2017

We studied the antibacterial effect and mechanical properties of PLA composites with in organic porous zeolite-type bacteriocides. The specimens were prepared by an intermeshing co-rotating twin screw extruder using different contents of inorganic bacteriocide. The degree of dispersion of the in organic bacteriocide in the PLA composite was confirmed by FE-SEM. The contents of Ag and Zn in the composite were also investigated by energy dispersive spectroscopy at different concentrations of the inorganic bacteriocide. The antibacterial effects were analyzed by turbidity analysis, shaking culture, and drop-test. The mechanical properties, such as the tensile and flexural properties, impact strength, and physical properties, were also investigated. As the content of inorganic bacteriocide increased, the antibacterial activity was increased, especially against Staphylococcus aureus. Mechanical properties, namely, tensile strength, elongation, flexural strength, and impact strength, tended to decrease with an increase in inorganic bacteriocide content, but the tensile and flexural modulus increased.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.376-390
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• 2003

The contents of chemical reaction in the science textbooks, used by starting from elementary school to college level, were investigated how much closely connected with them. For this purpose, nineteen subjects of chemistry contents were selected and the articulation analysis, classified into 5 criteria, was carried out. The results indicated that the articulation from elementary school to middle school looked quite acceptable, but there was a big gap from middle school to high school and the articulation from high school to college exhibited a big overlap and gap. Finally, the flow map of chemical reaction was suggested.

• Journal of the Korean Applied Science and Technology
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• v.23 no.4
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• pp.319-327
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• 2006

In order to prepare high-solid coatings, first acrylic resins (HSAs) which contain 80% solid were synthesized, and then the prepared resins were cured with isocyanate at room temperature. In the synthesis of HSAs, viscosity, number average molecular weight $(M_n)$ and conversion were $1372{\sim}2700$ cps, $1520{\sim}1650$ and $83{\sim}87%$, respectively. Among the four kinds of initiators used, tert-amylperoxy-2-ethyl hexanoate was the most proper one in the synthesis of HSAs. With increasing $T_g$ values, viscosity increased rapidly and molecular weight increased slowly. As a result of the examination of coated films, it was found that $60^{\circ}$ specular gloss, impact resistance, heat resistance and cross-hatch adhesion were good, and pencil hardness, drying time and pot life were poor.