• Analytical Science and Technology
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• v.19 no.3
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• pp.244-254
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• 2006

Flame retardants are added to prevent catching fire and to slow down the burning process. PBDEs are known to affect thyroid hormones and hormone disruption. The aim of this study was to propose a manual for determination of PBDEs, and investigate the accumulation of PBDEs(BDE-28, 47, 99, 100, 153, 154 and 183) in fish&shellfish and human milk samples. Pre-treatment for PBDEs determination, alkali digestion and L-L(Liquid-Liquid) extraction method could be applied to fish and shellfish. When Multi-layer column was used for cleaning up the sample, 50 mL of hexane and 100 mL of hexane:dichloromethane(9:1) solutions were used for pre- and post-elution, respectively. Activated-carbon column was optimized by a 100 mL of hexane:dichloromethane(3:1). The result of fish, highest concentration was detected in flatfish, 890 pg/g(wet weight). The other side, lowest concentration was detected in pollack, 40 pg/g(wet weight). The result of breast milk, PBDEs was detected 2,580 and 3,600 pg/g(lipid weight) from breast milk of Seoul and Juju, respectively. BDE-153 and 183 were not detected in all samples. There was no difference in PBDEs level was not difference between first and second delivery. In this study, we could find that PBDEs level in Korea is lower than other countries.

• Resources Recycling
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• v.32 no.3
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• pp.3-8
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• 2023

This study discussed production, demand, and future prospects of rubidium, which is an alkali group metal that is highly reactive to various media and requires carefulness in handling, but no significant environmental hazard of rubidium has been reported yet. Rubidium is used in various fields such as optoelectronic equipment, biomedical, and chemical industries. Because of difficulty in production as well as limited demand, the transaction price of rubidium is relatively high, but its detail information such as market status and potential growth is uncertain. However, if the mass production of versatile ultra-high-performance equipment such as quantum computers and the necessity of rubidium use in the equipment are confirmed, there is a possibility that the rubidium market will expand in the future. Rubidium is often found together with lithium, beryllium, and cesium, and may be present in granite containing minerals such as lepidolite and pollucite, as well as in seawater and industrial waste. Several technologies such as acid leaching, roasting, solvent extraction, and adsorption are used to recover rubidium. The maximum recovery efficiency of the rubidium from the sources and the processing above is generally high, but, in many practices, rubidium is not the main recovery target, and therefore the actual recovery effects should depend on presence of other valuable components or impurities, together with recovery costs, energy consumption, environmental issues, etc. In conclusion, although the current production and consumption of rubidium are limited, with consideration of the possible market fluctuations according to the emergence of large-scale demand sources, etc., further investigations by related institutions should be necessary.

• Korean Journal of Heritage: History & Science
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• v.56 no.4
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• pp.160-189
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• 2023

The Cheonjeon-ri petroglyph is inscribed with shale formation belonging to the Daegu Formation of the Gyeongsang Supergroup in the Cretaceous of the Mesozoic Era. This rock undergoes thermal alteration to become hornfels, and has a high hardness and dense texture. Rock-forming minerals have almost the same composition as quartz, alkali felspar, plagioclase, calcite, mica, chlorite and opaque minerals, but calcite is rarely detected in the weathered zone. The petroglyph forms a weathered zone with a certain depth, and there is a difference in mineral and chemical composition between weathered and unweathered zones, respectively. The CaO contents of the weathered zone were reduced by more than 90% compared to that of the unweathered zone, because calcite reacted with water and dissolved. As a result of calculating the surface weathering depth for the petroglyph with the transmission characteristics of X-rays, depth of the parts in falling off and exfoliation showed a depth of about 0.5 to 1 mm, but the weathering depth in most areas was calculated to be about 3 to 4 mm. This can be proved by the contents and changes of Ca and Sr. The surface discolorations of the petroglyph are distributed with different color density, and the yellowish brown discoloration is alternated with a thin biofilm layer, showing a coverage of 79.6%. Therefore, periodic preservation managements and preventive conservation monitoring that can effectively control the physicochemical and biological damages of the Cheonjeonri petroglyph will be necessary.

• Journal of Adhesion and Interface
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• v.24 no.3
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• pp.77-85
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• 2023

In this research, polymeric anionic surfactants having various molecular weights and acid values were synthesized using a continuous stirred tank reactor (CSTR). The CSTR has an advantage of higher production rate and more constant product properties compared to batch and semi-batch reactors. The polymeric surfactants were made using butyl acrylate as a hydrophobic group and acrylic acid as a hydrophilic group. The synthesized polymeric surfactants were ionized with alkali solution and were used as an anionic surfactant. To investigate the properties as a surfactant, the properties of the synthesized surfactant, such as acid value, critical micelle concentration (CMC) and molecular weight, were measured. The results showed that the acid values of the polymeric surfactants were 60 to 380 and a number average molecular weight were 8,000 to 13,000 g/mol. Also, it was found that the CMC was around 0.01 g/ml, which showed similar level values with ordinary surfactant. To prove the performance of the polymeric surfactant, acrylic emulsion PSAs were synthesized using the acquired polymeric surfactant. The results showed that the maximum peel strength of 21.24 N/25mm when acid value was 150 and molecular weight was 8,500 g/mol. The values of peel strength and initial tack of acrylic emulsion PSAs using polymeric surfactant synthesized in this study showed much higher than those of reference PSAs synthesized using ordinary anionic surfactant, SDS (Sodium Dodecyl Sulfate) and SDS/TRX (Triton X-100).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47
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• pp.15-32
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• 2002

The endeavors enhancing the grain quality of high-yielding japonica rice were steadily continued during 1980s-1990s along with the self-sufficiency of rice production and the increasing demands of high-quality rices. During this time, considerably great progress and success was obtained in development of high-quality japonica cultivars and quality evaluation techniques including the elucidation of interrelationship between the physicochemical properties of rice grain and the physical or palatability components of cooked rice. In 1990s, some high-quality japonica rice cultivars and special rices adaptable for food processing such as large kernel, chalky endosperm, aromatic and colored rices were developed and its objective preference and utility was also examined by a palatability meter, rapid-visco analyzer and texture analyzer, Recently, new special rices such as extremely low-amylose dull or opaque non-glutinous endosperm mutants were developed. Also, a high-lysine rice variety was developed for higher nutritional utility. The water uptake rate and the maximum water absorption ratio showed significantly negative correlations with the K/Mg ratio and alkali digestion value(ADV) of milled rice. The rice materials showing the higher amount of hot water absorption exhibited the larger volume expansion of cooked rice. The harder rices with lower moisture content revealed the higher rate of water uptake at twenty minutes after soaking and the higher ratio of maximum water uptake under the room temperature condition. These water uptake characteristics were not associated with the protein and amylose contents of milled rice and the palatability of cooked rice. The water/rice ratio (in w/w basis) for optimum cooking was averaged to 1.52 in dry milled rices (12% wet basis) with varietal range from 1.45 to 1.61 and the expansion ratio of milled rice after proper boiling was average to 2.63(in v/v basis). The major physicochemical components of rice grain associated with the palatability of cooked rice were examined using japonica rice materials showing narrow varietal variation in grain size and shape, alkali digestibility, gel consistency, amylose and protein contents, but considerable difference in appearance and texture of cooked rice. The glossiness or gross palatability score of cooked rice were closely associated with the peak, hot paste and consistency viscosities of viscosities with year difference. The high-quality rice variety "IIpumbyeo" showed less portion of amylose on the outer layer of milled rice grain and less and slower change in iodine blue value of extracted paste during twenty minutes of boiling. This highly palatable rice also exhibited very fine net structure in outer layer and fine-spongy and well-swollen shape of gelatinized starch granules in inner layer and core of cooked rice kernel compared with the poor palatable rice through image of scanning electronic microscope. Gross sensory score of cooked rice could be estimated by multiple linear regression formula, deduced from relationship between rice quality components mentioned above and eating quality of cooked rice, with high probability of determination. The $\alpha$-amylose-iodine method was adopted for checking the varietal difference in retrogradation of cooked rice. The rice cultivars revealing the relatively slow retrogradation in aged cooked rice were IIpumbyeo, Chucheongyeo, Sasanishiki, Jinbubyeo and Koshihikari. A Tonsil-type rice, Taebaegbyeo, and a japonica cultivar, Seomjinbyeo, showed the relatively fast deterioration of cooked rice. Generally, the better rice cultivars in eating quality of cooked rice showed less retrogradation and much sponginess in cooled cooked rice. Also, the rice varieties exhibiting less retrogradation in cooled cooked rice revealed higher hot viscosity and lower cool viscosity of rice flour in amylogram. The sponginess of cooled cooked rice was closely associated with magnesium content and volume expansion of cooked rice. The hardness-changed ratio of cooked rice by cooling was negatively correlated with solids amount extracted during boiling and volume expansion of cooked rice. The major physicochemical properties of rice grain closely related to the palatability of cooked rice may be directly or indirectly associated with the retrogradation characteristics of cooked rice. The softer gel consistency and lower amylose content in milled rice revealed the higher ratio of popped rice and larger bulk density of popping. The stronger hardness of rice grain showed relatively higher ratio of popping and the more chalky or less translucent rice exhibited the lower ratio of intact popped brown rice. The potassium and magnesium contents of milled rice were negatively associated with gross score of noodle making mixed with wheat flour in half and the better rice for noodle making revealed relatively less amount of solid extraction during boiling. The more volume expansion of batters for making brown rice bread resulted the better loaf formation and more springiness in rice breed. The higher protein rices produced relatively the more moist white rice bread. The springiness of rice bread was also significantly correlated with high amylose content and hard gel consistency. The completely chalky and large grain rices showed better suitability far fermentation and brewing. The glutinous rice were classified into nine different varietal groups based on various physicochemical and structural characteristics of endosperm. There was some close associations among these grain properties and large varietal difference in suitability to various traditional food processing. Our breeding efforts on improvement of rice quality for high palatability and processing utility or value-adding products in the future should focus on not only continuous enhancement of marketing and eating qualities but also the diversification in morphological, physicochemical and nutritional characteristics of rice grain suitable for processing various value-added rice foods.ice foods.

• The Journal of the Petrological Society of Korea
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• v.19 no.2
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• pp.141-156
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• 2010

Dokdo Island, Korea, is located in the East Sea belonging to back arc basin. In this study we examined petrology and geochemistry of massive tuffaceous breccia (MTB) from Dongdo (Eastern islet) and Seodo(Western islet), the two largest islands of Dokdo. Field studies and chemical analysis distinguish the MTB in Dongdo and Seodo. The Dongdo MTB (DMTB) is exposed up to 50 m on the ocean cliff and it has dominant basalt and trachybasalt with moderate amount of trachyte and scoria. On the other hand, Seodo MTB (SMTB), which is preserved between trachyte dike and trachyandesite, is composed of roughly equal amounts of basalt, trachybasalt and trachyte. The location of the islets were related to the source vent having in contact with underlying trachyte lava and differential pyroclastic deposits made them different characteristics. According to trace element analysis of trachytic volcanic clasts, the Ba concentration ranges from 66 to 103 ppm and Sr varies from 44 to 56 ppm in DMTB. However, Br and Sr in SMTB correspondingly showed relatively wide ranges: Br 785-1259 ppm and Sr 466-1230 ppm. These differential trends between DMTB and SMTB, along with the difference in P and Ti, indicate that the crystallization of alkali feldspar, feldspathoid, biotite, apatite and titanium took place differently. Nevertheless, DMTB and SMTB are similar in REE patterns and they are correspondingly characterized by high LREE, low HREE and similar $(La/Yb)_N$ values with 23.9-40.2 in DMTB and 27.4-32.9 in SMTB. These patterns suggest that Dongdo and Seodo might be originated from coeval magma suites. Dokdo island shows high concentrations of Ba, K and Rb. These signatures mark a result attributed to the mantle upwelling because the magma derived from the asthenosphere was metasomatized with subduction-related fluids.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.3
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• pp.133-141
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• 2007

There are produced more than 600,000 tons of seaweeds every year along the coast of the Korea. Jeonnam province, south-west coast area, of Korea is producing 93% of total amounts of seaweeds. The laver, sea mustard, and tangleweed maintain stability in the output and has been exported as a simple product processing through drying or salting. It was evaluated the low value-added products and limited the expansion for the consumption of seaweeds. The seaweeds contains 40-60% carbohydrate and structurally different compared with land plant. The dietary fiber from seaweeds has been known the function of facilitating the bowl movement, excretion the heavy metal in the body, lowering the blood cholesterol level, anti-coagulant of blood, and anticancer. Especially, brown algae including sea mustard, seaweed fusiforme, and tangleweed contains alginic acid, laminarin, mannitol, fucoidan which are lowering the blood cholesterol level, lowering blood pressure, and fusion of blood clot. Agar-agar, carrageenan, and porphyran compound in red algae are known to antimutagenicity and anticoagulant function. In spite of potential of seaweed as a main bio-resource, there are lack of research to facilitate the consumption with its functional properties and consumers are unsatisfied with simple processing products. Also, the seaweed by-product dump into the sea and cause pollution of the seawater. Therefore, there are needed the scheme to promote the consumption of seaweeds. The development of value-added products, finding functional properties from seaweeds, development the functional feed for animal using seaweed by-products, and utilization of unused algae for food or other industrial uses will increase fisherman's income as well as serve as an aid for the people health due to its functional properties. Using by-product of seaweed and unexploited seaweed are needed to development of bio-degradable food packaging material and functional feed for animal.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.413-426
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• 2014

This study was conducted to investigate changes of physicochemical properties and fatty acid compositions of rough rice stored at different storage temperatures and periods. So we analyzed texture, alkali digestion value (ADV), toyo glossiness value, pasting properties, fat acidity and fatty acid compositions of five rice varieties every 4 month on the condition of which rough rice had been stored at different temperatures (ambient and low temperature condition at $15^{\circ}C$) for 2 years. Hardness of cooked rice was increased by storage periods and cohesiveness of cooked rice was not considerably different among varieties according to storage temperatures and periods. ADV was significantly different among varieties and storage periods but not different with storage temperatures. Toyo glossiness value of cooked rice was continuously decreased from 4 months after storage regardless to storage temperature. The pasting properties were considerably affected by storage temperatures and periods of rough rice. Increase in peak viscosity, final viscosity and breakdown was observed but setback was decreased by storage periods. Fat acidity of brown rice was much higher than that of milled rice during storage of rough rice and tend to increase by storage period. Oleic acid among fatty acids of brown rice except Sindongin and Hitomebore tended to be decreased by storage periods and linoleic acid among fatty acids of brown rice of Hopum was decreased by storage periods. The contents of linoleinic acid and stearic acid among fatty acids of milled rice were comparatively decreased from 4 months after storage, whereas the content of palmitic acid tended to be increased by storage periods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.10 no.1
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• pp.93-101
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• 1981

This study is designed to investigate the properties of caramel color made by corn sugar molasses, a new material. Com sugar refined and then caramelized in the solution of pH 2-10 ranges using catalysts such as ammonium carbonate, glycine and lysine. The control solution are 10% hydrochloric acid and sodium carbonate. The result were as follow; The caramelization showed the intensity of very strong color when added 0.4% ammonium carbonate as a catalyst. Color hue appeared to have the same color hue of the yellow belt and the red belt when compared with standard color hue in alkali, but the samples blue belt in all pH ranges showed a strong color hue than the standard color hue. Also, the stability of tannin, table salt and alcohol was transparent in all pH ranges, but the stability of acid appeared hazy at pH 9-10. In the case of glycine as a catalyst, caramelization showed the intensity of strong color when added 0.8% glycine at pH 9. Color hue showed in the yellow belt, strong in the red belt and very strong in the blue belt in all pH ranges when compared with standard color hue. Stability of tannin, table salt, acid alcohol was quite stable. In the case of lysine as a catalyst, caramelization showed strong color intensity when added 0.4% lysine in pH 9. Stability of tannin, table salt, acid and alcohol was quite stable.

• Applied Biological Chemistry
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• v.21 no.2
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• pp.71-80
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• 1978

In an attempt to elucidate the fate of 3,4-DCA and TCAB in various French soils, uniformly $^{14}C-ring-labeled$ 3,4-DCA and TCAB mere utilized and the following results obtained. 1) The rate of breakdown of $^{14}C-3,4-DCA$ into $^{14}CO_2$ was relatively higher in the early stage than that in the later stage. In 6 months of incubation in alkaline soil (pH 7.9), the rate was as high as 6.5% at dose 1 (1.5 ppm) and as low as 1.92% at dose 2(94 ppm), whereas in organic acid soil (pH 5.5) the rate was 4.91% at dose 1 and 4.24% at dose 2, respectively, without making any great difference between the two levels. 2) At dose 1, 47.70% of the initial radioactivity of $^{14}C-3,4-DCA$ was bound to soil in organic acid soil and 29.49% bound in alkaline soil, whereas at dose 2, 38.40% in organic acid soil and 20.30% in alkaline soil, respectively. 3) The amount of formation of $^{14}C-TCAB$ from $^{14}C-3,4-DCA$ seems to depend largely on the concentration of 3,4-DCA applied rather than on soil types. At dose 2, the amount was 50% of the total radioactivity extracted in organic acid soil and 30% in alkaline soil, corresponding to 1.8% and 1.4% of the initial radioactivity applied to soil, respectively. Cis-TCAB also seemed to be formed at dose 2 in both soils. Meanwhile, at dose 1, even though $^{14}C-TCAB$ was detected in trace on tlc and glc in both soils, the amount does not exceed 2 to 3% of the radioactivity extracted, corresponding to 0.05 to 0.1% of the initial radioactivity. 4) The rate of breakdown of $^{14}C-TCAB$ into $^{14}CO_2$ ranged from 0.05 to 0.20% in all the four soils. Most of the applied $^{14}C-TCAB$ remained intact after 3 months, not producing any detectable metabolites. 5) The fact that much more $^{14}C-TCAB$ was adsorbed to alkaline soil than to the other soils strongly indicates that in alkaline condition trans-isomer was converted tocisisomer which has the higher adsorption affinity than the former.