• The Korea Journal of Herbology
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• v.27 no.6
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• pp.43-48
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• 2012

Objectives : This study was investigated to determine the contents of pesticide residues and sulfur dioxide residues in commercial herbal medicines in Korea. Methods : Chromatographic test was performed on 100 samples consisted with 10 kinds of medicinal plants including improted and domestic products. To establish 19 pesticide residues (DDE, DDD, DDT, Dieldrin, Methoxychlor, BHC isomers, Aldrin, Endosulfan isomers, Endrin, Captan, Procymidone, Chlorpyrifos and Imidacloprid) in commercial herbal medicines, chromatographic equipments were used with the gas chromatography-mass detector and gas chromatography-electron capture detector for qualitative analysis. The imidacloprid analysis was performed by high performance liquid chromatograpgy-ultraviolet detector at 270 nm UV wavelength. The contents of sulfur dioxides were analyzed by modified Monnier-Williams method. All methods were based on notification procedure of Korea Food & Drug Administration (KFDA). Results : The residual pesticides were not founded in improted and domestic samples. Among 100 samples, the residues of sulfur dioxide in 73 samples were not detected and 25 samples showed contents in the range of 0~21.90 mg/kg. The excess samples of MRLs were 2 samples (30 mg/kg to medicinal herbs), Asiasari Radix et Rhizoma (Imported product) and the average amount of sulfur dioxide in 2 unsuitable samples were 14.83 mg/kg. These samples were found to transgress KFDA regulatory guidance of residual sulfur dioxide. Conclusion : These results are able to use as basic data to improve the reliability and value of commercial medicinal herbs.

• Composites Research
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• v.34 no.6
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• pp.406-411
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• 2021

PEM (proton exchange membrane) fuel cells generate only water as a by-product, and thus are in the spotlight as an eco-friendly energy source. Among the various components composing the stack of the fuel cell, research on the bipolar plate that determines the efficiency of the fuel cell is being actively conducted. The composite bipolar plate has high strength, rigidity and corrosion resistance, but has the disadvantage of having a relatively low electrical conductivity. In this study, to overcome these shortcomings, a gas diffusion layer (GDL)-composite bipolar plate assembly was developed and its performance was experimentally verified. The graphite foil coating method developed in the previous study was applied to reduce the contact resistance between the bipolar plate and the GDL. In addition, in order to improve electron path in the stack and minimize the contact resistance between the GDL and the bipolar plate, a GDL-bipolar plate assembly was fabricated using a thin metal foil. As a result of the experiment, it was confirmed that the developed GDL-bipolar plate assembly had 98% lower electrical resistance compared to the conventional composite bipolar plate.

• Journal of Wetlands Research
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• v.25 no.1
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• pp.1-13
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• 2023

Coastal shellfish in the shallow aquaculture waters form carbon contained shells as they grow. The existing researches showed that carbon flux can be improved, if the shells are re-treated by the carbon stored methods. In the present study, firstly, the mechanism and the quantitative flux of carbon dioxide in the shellfish individual have been analyzed. The re-treated methods of the useful by-product in the shellfish aquaculture, shells, have been reviewed. Finally, the potential effects to reduce the greenhouse gas has been suggested, if the shells can be properly re-treated.

• Clean Technology
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• v.15 no.1
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• pp.42-46
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• 2009

Solvent-free direct preparation of dichloropropanol (DCP) from glycerol (by-product of bio-diesel production) and hydrochloric acid gas was carried out over acetin catalyst in a gas-liquid batch reactor. For this purpose, acetin mixture and triacetin were used as a homogeneous acetin catalyst. Performance in the acetin-catalyzed reaction was compared to that in the non-catalytic reaction under the same reaction conditions ($110^{\circ}C$, 3 bar, 3 h). Conversion of glycerol in the acetin-catalyzed reactions was ca. 3% higher than that in the non-catalytic reaction, and selectivity for dichloropropanol in the acetin-catalyzed reactions was ca. 50% higher than that in the non-catalytic reaction. It was also revealed that the catalytic performance of triacetin was ca. 2% higher than that of acetic mixture.

• Journal of Convergence for Information Technology
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• v.12 no.2
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• pp.149-156
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• 2022

In this paper, it was attempted to form a titanium (Ti: Titanium) thin film using the atmospheric pressure plasma process technology for the conductor, which is the main component of the optical sensor. The atmospheric plasma equipment was remodeled. A 4-inch Ti target for sputter was etched using CF4 gas, and the by-product was coated on a glass sample. These by-products were formed up to about 2 cm, and could be divided into 15 areas according to color. Surface shape and constituent elements were analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), respectively. Electrical properties using 4-point probe equipment were also measured. If the process is performed by positioning the sample at about 4.5 mm to 5 mm from the target, a uniform Ti thin film will be deposited. However, it was found that the thin film contained a significant amount of fluorine, which greatly affects the electrical properties of the thin film. Therefore, additional experiments and studies should be performed to remove or minimize fluorine during deposition.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.550-554
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• 2023

Fossil energy sources are limited in their sustainable use and expansion due to global warming caused by carbon dioxide emissions. Hydrogen is considered as a promising alternative to traditional fossil fuels. To ensure the stable long-term storage, it is necessary to accurately predict its thermodynamic properties at cryogenic temperatures. Therefore, this study aimed to investigate thermodynamic properties, such as saturated vapor pressure and density, enthalpy, and entropy of liquid and gas, using cubic equations of state that demonstrate relatively simple relationships. Among the three types of equations of state (Redlich-Kwong (RK), Soave-Redlich-Kwong (SRK), and Peng-Robinson (PR)), the SRK model exhibited relatively accurate prediction results for various physical properties.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.603-616
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• 2007

Roy Huddle, having invented the coated particle in Harwell 1957, stated in the early 1970s that we know now everything about particles and coatings and should be going over to deal with other problems. This was on the occasion of the Dragon fuel performance information meeting London 1973: How wrong a genius be! It took until 1978 that really good particles were made in Germany, then during the Japanese HTTR production in the 1990s and finally the Chinese 2000-2001 campaign for HTR-10. Here, we present a review of history and present status. Today, good fuel is measured by different standards from the seventies: where $9*10^{-4}$ initial free heavy metal fraction was typical for early AVR carbide fuel and $3*10^{-4}$ initial free heavy metal fraction was acceptable for oxide fuel in THTR, we insist on values more than an order of magnitude below this value today. Half a percent of particle failure at the end-of-irradiation, another ancient standard, is not even acceptable today, even for the most severe accidents. While legislation and licensing has not changed, one of the reasons we insist on these improvements is the preference for passive systems rather than active controls of earlier times. After renewed HTGR interest, we are reporting about the start of new or reactivated coated particle work in several parts of the world, considering the aspects of designs/ traditional and new materials, manufacturing technologies/ quality control quality assurance, irradiation and accident performance, modeling and performance predictions, and fuel cycle aspects and spent fuel treatment. In very general terms, the coated particle should be strong, reliable, retentive, and affordable. These properties have to be quantified and will be eventually optimized for a specific application system. Results obtained so far indicate that the same particle can be used for steam cycle applications with $700-750^{\circ}C$ helium coolant gas exit, for gas turbine applications at $850-900^{\circ}C$ and for process heat/hydrogen generation applications with $950^{\circ}C$ outlet temperatures. There is a clear set of standards for modem high quality fuel in terms of low levels of heavy metal contamination, manufacture-induced particle defects during fuel body and fuel element making, irradiation/accident induced particle failures and limits on fission product release from intact particles. While gas-cooled reactor design is still open-ended with blocks for the prismatic and spherical fuel elements for the pebble-bed design, there is near worldwide agreement on high quality fuel: a $500{\mu}m$ diameter $UO_2$ kernel of 10% enrichment is surrounded by a $100{\mu}m$ thick sacrificial buffer layer to be followed by a dense inner pyrocarbon layer, a high quality silicon carbide layer of $35{\mu}m$ thickness and theoretical density and another outer pyrocarbon layer. Good performance has been demonstrated both under operational and under accident conditions, i.e. to 10% FIMA and maximum $1600^{\circ}C$ afterwards. And it is the wide-ranging demonstration experience that makes this particle superior. Recommendations are made for further work: 1. Generation of data for presently manufactured materials, e.g. SiC strength and strength distribution, PyC creep and shrinkage and many more material data sets. 2. Renewed start of irradiation and accident testing of modem coated particle fuel. 3. Analysis of existing and newly created data with a view to demonstrate satisfactory performance at burnups beyond 10% FIMA and complete fission product retention even in accidents that go beyond $1600^{\circ}C$ for a short period of time. This work should proceed at both national and international level.

• Journal of Climate Change Research
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• v.2 no.1
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• pp.15-32
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• 2011

Due to greenhouse gas increased by human activities, abnormal climate changes are continuously occurring everywhere in the world and internationally people make efforts to reduce the emission of greenhouse gas. Our country also is making endeavors to realize low carbon society on the foundation of the green growth and for this low carbon consumption pattern settlement through green life is necessary. Therefore for the nationals the offering of the information on greenhouse gas emission that is reduced through the change to low carbon life is required. In this study the objects are beef and wine whose weight of import is high among the beverages and foods consumed in the country and we calculated the food mileage and emission of carbon dioxide of the domestic and foreign product beef and wine and estimated the potential amount that can be reduced when replacing the imported products with domestic products. As the year 2007 being standard if we replace 10% of imported beef with domestic products it is possible to reduce 14,000 tons of carbon dioxide per year and on one day out of a year if we replace imported beef with domestic beef the reduction of 384 tons of carbon dioxide is appeared to be possible. In the same standard year if we replace 10% of imported wine with domestic product we can reduce 1,396 tons and on one day out of a year if we replace imported wine with domestic wine reduction of 38 tons of carbon per year appeared to be possible. Through active promotion and expansion of variety of domestic foods and beverages in the real life of the nationals the consumption pattern of natural low carbon life should be achieved and offering of more systematized greenhouse gas emission DB is thought to be necessary.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.4
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• pp.617-626
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• 1996

Nitrogenous compounds in hydrolysate of skipjack processing by-product(SPB) was increased 6.4 times in amount comparing that of raw SPB. The major compounds in hydrolysate were anserine, histidine, leucine, hydroxyproline, arginine, phenylalanine and taurine, and composed 56.25% of total nitrogenous compounds. In fatty acid composition, the highest amount was saturated fatty acids in both samples. Polyunsaturated fatty acids such as $C_{20:5}$ and $C_{22:6}$ were increased after hydrolysis. A total of 99 volatile compounds was detected in raw and hydrolysate of SPB by vacuum simultaneous steam distillation-solvent extraction/gas chromatography/mass chromatorgraphy. Of these, 75 compounds were identified in raw SPB, while 72 compounds were identified in hydorlysate of SPB. There compounds were composed mainly of 28 aldehydes, 20 ketones, 19 alcohols, 5 nitrogen containing compounds, 5 aromatic hydrocarbons, 4 furans and 12 miscellaneous compounds. Levels of aldehydes and aromatic hydrocarbons decreased after hydrolysis, whereas heterocyclic compounds such as pyrazies, furans increased.

• Food Science of Animal Resources
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• v.31 no.3
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• pp.477-483
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• 2011

In this study, the most preferred trans fatty acid analysis methods, AOAC 996.06 and the Korea Food and Drug Administration official method, were reviewed and modified to apply to dairy products and dairy products imported into the Republic of Korea for evaluating trans fatty acid (TFA) content. The Rose-Gottlieb method for total fat analysis was validated with accuracy and precision parameters by analyzing infant formula standard reference material provided by the National Institute for Standards and Technology. The accuracy and precision data satisfied the CODEX guidelines. TFAs were analyzed with a resolution of 1.5 for 45 min using the modified oven temperature program. This modified method was applied to 45 dairy products from 11 countries. Average TFA contents in these imported dairy products ranged from 0.1 to 5.4 g per 100 g product. The majority of dairy products imported into the Republic of Korea were cheeses. TFA contents in the cheeses were 0.1 to 2.4 g per 100 g cheese. TFA contents in other dairy products were 1.7 to 5.4 g per 100 g product. These TFAs content variations can be explained by the trans fatty acids naturally present in ruminant milk formed by bacterial bio-hydrogenation in the rumen of cows and the different vegetable fat used as ingredients in the final products.