• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.449-455
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• 2021

Composite materials are substances that are configured to have excellent physical properties by combining the properties of a single substance, and are in the limelight as materials that exceed the performance of metals and polymers. However, it has the disadvantages of long cycle time and high unit price, and much research is being performed to overcome these disadvantages. In this study, we developed an epoxy resin curing agent that can shorten the time required for mass production of composite materials, and tried to expand the applicability of objections by imparting flame retardancy. The epoxy resin used as a basic substance utilized two types of bisphenol F and resorcinol structure, which was further modified using 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide (DOPO) to impart flame retardancy. Triethylphosphate (TEP) and bis [(5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl] methyl phosphonate P,P'-dioxide (FR-001) were used as additives, seven kinds of compositions were blended, thermal characteristics (gelation time, glass transition temperature) and flame retardant performance were evaluated. We successfully developed an epoxy matrix that can be applied to high pressure resin transfer molding (HP-RTM) process.

• Food Science and Industry
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• v.50 no.1
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• pp.67-73
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• 2017

Control of food pathogens is critical in food safety field. Norovirus is one of the major causes of gastroenteritis and food poisoning worldwide, however, currently, there is not a vaccine or a specific drug available for its treatment. There are several methods to inactivate norovirus during food processing by chemical and physical treatments, however, the use of natural substance has been suggested as an optional strategy due to their safety and consumer preference. In this study supported by Ministry of Food and Drug Safety in Korea, we identified novel plant-derived substances with significant anti-norovirus activities. The aim of this project was to determine the antiviral activity of a wide range of natural substances, including plant-derived extracts and essential oils, using a norovirus surrogate system, human norovirus replicon-bearing cells, and mouse in vivo experiments. During the activity screening test, we identified novel anti-norovirus substances or oils using plaque assay with MNV-1. Six selected substances were formulated into an optimum mixture and used as an ingredient for salad sauce of which anti-novovirus activity was confirmed(pending for patent and paper submission). The potential application of selected natural substances as a metal surface sanitizer was also tested. Interestingly, the mixture of selected natural compounds showed a significant inhibitory effect against norovirus. These results suggest that these substances may be used as food ingredient with anti-norovirus antivity or components for surface sanitizers to prevent norovirus contamination.

• Journal of the Korean Society of Safety
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• v.37 no.6
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• pp.9-17
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• 2022

Qualifying quantities (upper tier (UT) and lower tier (LT)) are designated for the regulation of toxic substances. In this study, we aimed to establish systematic criteria for the qualifying quantities by comparing the South of Korea chemical control act with the European Seveso III Directive (Seveso III). In Seveso III, qualifying quantities are defined as "hazard categories" applying GHS (Globally Harmonized System of Classification and Labelling of Chemicals), and LTR (lower-tier requirements) and UTR (upper-tier requirements) are determined. The Pro HC (proposed hazard categories) were relevant to the GHS classification of toxic substances and were compared with the currently regulated qualifying quantities. Furthermore, we estimated the Pro LTR (proposed lower-tier requirements) and Pro UTR (proposed upper-tier requirements) corresponding to each Pro HC. Consequently, it was supposed that LT and UT were selected based on GHS like those of Seveso III. Therefore, designation criteria for qualifying quantities should be established by setting the Pro HC such as in Seveso III, rather than designating the qualifying quantities of toxic substances by itself individually. In addition, qualifying quantities should not be delegated to GHS classifications (H302, H341, H411) that do not meet the criteria for the designation of toxic substances, and the corresponding substances should be excluded from classification as toxic substances. This study provides insights into the selection of hazard categories and criteria for qualifying quantities of toxic substances.

• Natural Product Sciences
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• v.11 no.1
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• pp.50-53
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• 2005

Bioassay-directed fractionation of the lipophilic extract of a marine sponge Sarcotragus sp. led to the isolation of a known trisoxazole containing macrolide, mycalolide B (1). Its structure was identified by NMR and MS analyses. This is the first report on the isolation of macrolide from a sponge of the genus Sarcotragus (Order: Dictyoceratida).

• Applied Chemistry for Engineering
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• v.17 no.2
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• pp.119-124
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• 2006

Natural organic matter (NOM) should be carefully considered in terms of its constituent and effect because NOM is complex substances that occur in spatially and seasonally varying concentrations in natural water. This review presents characteristics of natural organic matter present in water. These compounds mainly include humic substances, carbohydrates, proteins (amino acids), hexosamines, fats, oils, greases, and trace organic compounds (endocrine disrupting chemicals and pharmaceuticals and personal care products).

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3122-3127
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• 2007

Water resource can be examined using biological sensors. Algae has been one of the biological sensors used to evaluate and monitor the water pollution. The monitoring system, however, could determine whether the examined water was safe or not. It needs additional expensive chemical test to figure out the cause of the water pollution. In this study, an endeavor is given to identify the toxicant in the water using the shape of the chlorophyll fluorescence induction curve(FIC) from algae using monitoring system. Fundamental curves are obtained from the experiments with specified amount of toxicant. Baysian method is utilized to determine the unknown toxicant in the water by comparing it with the fundamental curves. The results shows that the proposed method works fairly well.

• Proceedings of the Korean Society of Food Science and Nutrition Conference
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• 2004.11a
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• pp.99-101
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• 2004

An important aspect of indigenous medicine is the ability of traditional societis to manipulate the environment for their own benefit, for example for their health care. In Indonesia, this indigenous medicine is called Jamu. Jamu mostly consists of a mixture of herbals of the genus Curcuma, Zingiberaceae. There are 19 species of curcuma grown in Indonesia. Eleven of them are popular in the jamu preparations. Ethnopharma-cological surveys have shown that 50% of these species are used for post partum protection, dismenorrhea, 30% are used for the treatment of stomache and as cosmetics, 20% for the treatment of various diseases such as fever, worms, asthma, etc. Chemical studies show that they contain curcuminoids, volatile oils, flavonoids, starch, and resinous substance. Pharmacological studies of extracts and isolated bioactive compounds have shown that they have a broad pharmacological activity such as antibacterial, antifungal, anti-inflammatory, choleretic, antihepatotoxic, antitumor, antioxidant, and antihyperlipidemic activity.

• Food Science and Preservation
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• v.6 no.1
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• pp.66-70
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• 1999

The mechanism of natural removal of astringency and seasonal changes of tannin substance in sweet persimmon(Fuyu) and astrigent persimmon(Chungdo Bansi)were investigated. Tannin productivity of astringent persimmon fruit was higher than that of sweet perimmon fruit during growth. In the reactivity of tannin to acetaldehyde, it was observed that tannin from sweet persimmon have a milder chemical properties than that from astrigent persimmon. The threshold value of astringency on sweet persimmon tannin was higher than that of astrigent persimmon tannin. Tannin substances from sweet persimmon distributed mainly in lower molecular weight range at harvest stage, but those from astrigent persimmon distributed mainly in higher molecular weight range. Therefore, the natural removal of astringency was related to difference of tannin productivity, threshold value of astringency, reactivity and qualitative difference of tanni.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.139-148
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• 1995

In this paper we report the device of a multi-channel clinical instrument developed for determi¬nation of the levels of the urinary urobilinogen, glucose, ketone, bilirubin, protein, ascorbic acid, nitrite, pH, occult-blood, specific gravity, and leukocytes semiquantitatively. The test parameters are expressed on the dry test strips as a range of color intensities by chemical reactions. The instrument measures the value of each substance by reading the reflectance light emanated from the test strips. We also designed the reagent strip cassette and loader in order to intercept the outside interference. The loader can be operated semi-automatically. The light source is consisted on light emitting diodes at three specific wavelengths (560 nm, 610 nm, 650 nm). Precision of the system was evaluated by testing a series of commercial control urine samples. Furthermore, the performance of the instrument was compared with two other test methods on the urine samples from 100 persons. Our results showed a good repeatability between tests and a satisfactory agreement between the readings by our instrument and visual evaluation.

• Korean Journal of Child Studies
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• v.30 no.6
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• pp.125-137
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• 2009

This study reviews facts and trends of harmful environments in the last decade that negatively affected children's development. Younger children have been exposed to harmful media, drugs, facilities, and objects. A matter of chemical substances contaminating in-door air has become quite controversial, recently. In order to provide a better understanding of harmful environments against children, there are great needs for a survey covering all ages based on the clear definition of the term harmful environments, research identifying its causal effects on child development in the context of both parent-child and peer relationships, and a longitudinal study processing its effects in a life-span perspective. It is suggested that by providing parent education and a plenty of cultural facilities as social efforts to create sound family culture, psycho-social and physical environments of children are improved. Furthermore, legal regulations and supervision on harmful environments are needed to be strengthened.