• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.1085-1093
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• 2017

Plasticizers are materials added to give softness and elasticity to plastics having rigid properties to give soft properties as products, and they are mainly added to high molecular materials to give flexibility to improve workability and to improve cold resistance, resistance to volatility and electrical properties. It is used for the purpose. Most plasticizers are inert liquids, similar in function to solvents but with high molecular weight and no volatility. In addition, when dissolved in petrochemical products, only the plasticizer is separated by the matrix effect with other compounds, and qualitative and quantitative analysis. In this study, qualitative and quantitative analysis of DOA and DOP, which are representative components of petrochemical products, were conducted using MD-GC/MS and developed an optimal plasticizer analysis method.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.421-427
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• 2015

Angelica gigas Nakai is one of the most widely used herbal medicines and is known to have many pharmaceutical effects including an anti-oxidant, anti-cancer etc. This study was carried out to investigate an effect of fertilization on leaf yield, production of dry-matter and accumulation of pyranocurmarine compounds such as decursin (DE) and decursinol angelate (DA) in Angelica gigas Nakai. Effect of fertilization was determined from response surface regression equation composing of 2 by 3 factorial arrangement of urea, sodium dihydrogen phosphate and potassium chloride. Yield of leaf in Angelica gigas Nakai significantly increased until 100 days after transplanting. Production of leaf also tended to increase with increasing nitrogen fertilization. Model of regression equation showed that leaf production depended upon nitrogen ($Pr>{\mid}t{\mid}$ : 0.087, 0.256 and 0.079). Also, statistical results between nitrogen application level and production of dry-matter showed significant relationship (p<0.05) and contents of dry-matter was highest in 10 kg 10a-1 treatment on 24 Sep. Active compound isolated and purified from leaf and root of Angelica gigas Nakai was identified as DE and DA by gas chromatograph-mass spectrophotometry (GC-MS). Concentration of DA as prevalent compound in leaf was highest on 20 Aug. but decreased on 24 Sep. Amount of DE and DA accumulated in Angelica gigas Nakai significantly increased with growth stages and nitrogen level. The result of our investigation imply that nitrogen fertilization is important factor for production of leaf and accumulation of pyranocurmarine in Angelica gigas Nakai as a medicinal/food materials.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.611-619
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• 2019

This study was carried out to investigate fuel decomposition characteristics and coke formation according to types of endothermic fuels and methods of catalyst molding. Methylcyclohexane (MCH), n-dodecane, and exo-tetrahydrodipentadiene (exo-THDCP) were used as the endothermic fuels. As a catalyst, USY720 supported with platinum was used. It was manufactured by only using pressure to disk-type, or pelletized with a binder and a silica solution. The characteristics of the catalysts according to the molding method were analyzed by X-ray diffraction analysis, scanning electron microscopy, nitrogen adsorption-desorption isotherm, and ammonia temperature programmed desorption analysis. The reaction was carried out under conditions of high temperature and high pressure ($500^{\circ}C$, 50 bar) in which the fuel could exist in a supercritical state. The product was analyzed by gas chromatograph/mass spectrometer and the coke produced by the catalyst was analyzed by thermogravimetric analyzer. After the reaction, the composition of the products varied greatly depending on the structure of the fuel. In addition, the crystallinity and surface properties of the catalysts were not changed by the method of catalyst molding, but the changes of the acid sites and the pore characteristics were observed, which resulted in changes in the amount and composition of products and coke.

• Journal of the Korean Chemical Society
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• v.65 no.4
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• pp.249-253
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• 2021

Litter and manure were obtained at a cow house of a livestock farm in Andondg city. We examined the change of formation of nitrogen and phosphorous from these samples and tried to suggest a more useful and realistic way for removing them. Constituent and its content of sample were identified by XRF. NO₂^-, NO₃^-, and PO₄^3- ions and NH₄⁺, T-P and T-N released from sample were analyzed using ion chromatograph and UV/Vis spectrometry, respectively. As the results of this study, the ammonia nitrogen in the early stage of cow excretion is a need to make an ammonia gas state that can be immediately volatile by increasing the pH. Nitrogen and phosphorous, the main source of nutrition in green algal bloom can be removed by transforming insoluble salts such as calcium phosphate (CaHPO₄·3H₂O) and struvite (NH₄MgPO₄·6H₂O), respectively, with addition of Ca and Mg after stimulating fermentation of manure.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.228-235
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• 1997

This experiments were conducted to determine the effect of allelopathy and autotoxicity in alfalfa. Among several alfalfa cultivars, the substances exudated from seven cultivars including Medicago sativa, c.v. Luna, Sparta, Magnum, Husky, Milkmaker, Challenger and Anchor inhibited the germination and seedling growth of radish, ranging from 60 to 80％. When allelopathic substances were exudated from the soil of the alfalfa-cultivated field, the increased levels of substance retarded the germination rate and seedling growth of radish and alfalfa. The inhibition rate was about 80％, compared with that of control. Thus, this study indicates that the allelopathy and autotoxicity substances of alfalfa influenced the germination and seedling growth in alfalfa itself and radish. When allelopathic substances were analysed by using gas chromatograph, several kinds of phenol compounds were detected as follows; Salicylic acid, hydroxybenzoic acid, vanillic acid, syringic acid, coumaric acid, and ferulic acid.

• Analytical Science and Technology
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• v.21 no.6
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• pp.443-458
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• 2008

Brominated flame retardants (BFRs) are chemical compounds that inhibit the combustion of organic materials by scavenging free radicals that would otherwise encourage the spread of flames. These compounds are found in a wide variety of materials including paints, plastics, textiles, furniture and electronics. Mounting evidence, however, suggests that the non-reactive BFRs can easily leach into the environment and pose significant environmental and health concerns. PBDDs/PBDFs are often formed in the process of manufacturing brominated flame retardants and from the combustion of waste products containing flame retardants BFR. Therefore, this paper describes the general characteristics, management status, residual concentration in environments and analytical method.

• Conservation Science in Museum
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• v.30
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• pp.47-70
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• 2023

In 2019, the first excavation survey was conducted at the Temple Site No. 4 of Yaksugok Vally in Namsan Mountain, Gyeongju to determine the original location of the headless stone Buddha statue and the structure of the temple site. The survey excavated a stone Buddha head that was confirmed in a comparative analysis to be petrologically and mineralogically identical to a headless stone seated Buddha statue found derelict nearby. Traces of gold leaf and black adhesive were found on a portion of the right side of the face of the Buddha head buried in the ground. Since it is exceedingly rare for lacquer and gilding techniques to have been applied to a large stone Buddha statue without a base layer, this study examines the gilding techniques of the time by analyzing the characteristics of the materials used. In this process, the structure of the gold foil was observed through analytical microscopy and scanning electron microscopy with energy dispersive X-ray spectrometry, and the gold (Au) component was identified. As a result of analyzing the black adhesive using pyrolysis-gas chromatograph/mass spectrometry (pyrolysis-GC/MS), pyrolysis compounds such as hydrocarbons, fatty acids, catechol, and catechol oxidation products were detected. This was identical to the characteristics identified upon analyzing lacquer collected from species of lacquer tree whose main component is urushiol. Therefore, it was confirmed that the stone Buddha head excavated from the Temple Site No. 4 of Yaksugok Valley was separated from a nearby stone seated Buddha statue, and that the gold foil was attached using lacquer sap collected from lacquer trees, which grow in Korea, China, and Japan.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.8-11
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• 2012

Purpose : Among quality control items, the radiochemical impurity must be below 10% of total radioactivity. In this regard, as the recently commercialized automatic synthesis module produces a large amount of 18F-FDG, radiolysis of radiopharmaceuticals is very likely to occur. Thus, this study compared the changes in radiochemical purity regarding radiolysis of $^{18}F$-FDG according to automatic synthesis module. Materials and methods : Cyclotron (PETtrace, GE Healthcare) was used to produce $^{18}F$ and automatic synthesis module (FASTlab, Tracerlab MX, GE Healthcare) was used to achieve synthesis into FDG. For radiochemical purity, Radio-TLC Scanner (AR 2000, Bioscan), GC (Gas Chromatograph, Agilent 7890A) was used to measure the content of ethanol included in $^{18}F$-FDG. Glass board applied with silica gel ($1{\times}10cm$) was used for stationary phase while a mixed liquid formed of acetonitrile and water (ratio 19:1) was used for mobile phase. High-concentration and low-concentration $^{18}F$-FDG were produced in each synthesis module and the radiochemical purity was measured every 2 hours. Results : The purity in low-concentration (below 2.59 GBq/mL) was measured as 99.26%, 98.69%, 98.25%, 98.09% in Tracerlab MX and as 99.09%, 97.83%, 96.89%, 96.62% in FASTlab according to 0, 2, 4, 6 hours changes, respectively. The purity in high-concentration (above 3.7 GBq/mL) was measured as 99.54%, 96.08%, 93.77%, 92.54% in Tracerlab MX and as 99.53%, 95.65%, 92.39%, 89.82% in FASTlab according to 0, 2, 4, 6 hours changes, respectively. Also, ethanol was not detected in GC of $^{18}F$-FDG produced in FASTlab, while 100~300 ppm ethanol was detected in Tracerlab MX. Conclusion : Whereas the change of radiochemical purity was only 3% in low-concentration $^{18}F$-FDG, the change was rapidly increased to 10% in high-concentration. Also, higher radiolysis were observed in $^{18}F$-FDG produced in FASTlab than Tracerlab MX. This is because ethanol is included in the synthesis stage of Tracerlab MX but not in the synthesis stage of FASTlab. Thus, radiolysis is influenced by radioactivity concentration than the inclusion of ethanol, which is the radioprotector. Therefore, after producing high-concentration $^{18}F$-FDG, the content must be diluted through saline to lower concentration.

• Economic and Environmental Geology
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• v.50 no.2
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• pp.171-180
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• 2017

This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu during the period from July 2015 to August 2016. Also, we confirmed the errors that $HCO_3{^-}$ concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved $CO_2$ in hot spring waters was analyzed using gas chromatograph in Lee et al. (2014). Improving this, from 2015, we used TOC-IC to analysis dissolved $CO_2$. Also, we analyzed the $Na_2CO_3$ standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the $HCO_3{^-}$ concentrations of 2014 samples. During the period of study, $CO_2/CH_4$ in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction conditions, and carbon in volcanic gases become more favorable to distribute into $CH_4$ or CO than $CO_2$. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of $CO_2$ which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cation, and some trace elements (As, Cd, Re).

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.716-723
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• 1995

The fucoidan purified from Korean brown seaweed, Ecklonia stolonifera was characterized on molecular structure and blood anticoagulant activities. Extraction was conducted at $100^{\circ}C$ with water and repeated twice. The crude fucodian was 151.1g out of 20.0 kg of Ecklonia stolonifera. The Fucoidan-1, which was purified from crude fucoidan using calcium chloride and cetyl pyridium chloride (CPC), was 35.2% against crude fucoidan. Fucoidan-5 was obtained approximately 28.1% from Fucoidan-1 through DEAE-Toyopearl 650 M ion-exchange column chromatography and showed one band by cellulose acetate electrophoresis. The molecular weight of Fucoidan-5 was estimated to be about 21,000∼23,000 dalton by Sephacryl S-300 gel filtration chromatography. Fucoidan-5 consists of 35.7% of fucose and 4.3% of galactose and the molar ratio of fucose and sulfate was about one to one. IR spectrum of Fucoidan-5 showed absorption at $1240\;cm^{-1}\;and\;850\;cm^{-1}$ and specific rotation value, $[\alpha]$, was $[\alpha]$. These results suggests that the sulfate maybe bind at $C_{4}$ carbon on ${\alpha}-L-fucose$. Gas chromatograph of methyl alditol acetate revealed that Fucoidan-5 is a fucose containing sulfated polysaccharide with $({\alpha}l-2)\;or\;({\alpha}l-2)$ glycosidic linkage. Anti-thrombin activity of the Fucoidan-5 was estimated as 1.4 time stronger than heparin. From above results, the purification methods using CPC and ion exchange chromatography is effective tools for obtaining highly purified fucoidan from Gompi, Ecklonia stolonifera.