• 한국환경과학회지
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• 제12권10호
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• pp.1061-1069
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• 2003

The adsorption behaviors of strontium and cesium ions on fly ash, natural zeolites, and zeolites synthesized from fly ash were investigated. The zeolites synthesized from fly ash had greater adsorption capabilities for strontium and cesium ions than the original fly ash and natural zeolites. The maximum adsorption capacity of synthetic zeolite for strontium and cesium ions was 100 and 154 mg/g, respectively, It was found that the Freundlich isotherm model could fit the adsorption isotherm. The distribution coefficients (K$\_$d/) for strontium and cesium ions were also calculated from the adsorption isotherm data, The distribution coefficients decreased with increasing equilibrium concentration of strontium and cesium ions in solution. By studying the removal of cesium and strontium ions in the presence of calcium, magnesium, sodium, potassium, sulfate, nitrate, nitrite, and EDTA (in the range of 0.01 - 5 mM) it was found that these coexistence ions competed for the same adsorption sites with strontium and cesium ions.

• 한국식품과학회지
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• 제54권3호
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• pp.264-271
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• 2022

본 연구에서는 살균 및 비가열압착한 들깨오일(superilla)을 활용하여 영양성분을 확인하고 기능성 식품으로서의 가능성을 알아보기 위해 시판되는 들기름과 비교실험을 수행하였다. 수분 함량과 pH는 CPPO에서 높았고, 구리, 코발트, 칼슘 함량은 SRPO에서 높았다. 총 비타민 E, 토코페롤, 리놀렌산 함량은 LPPO에서 더 높았다. 총 폴리페놀 함량과 ABTS 라디칼 소거활성은 SRPO에서 가장 높은 수치를 보였으며, 아질산염 소거능 측정값은 CPPO에서 가장 높았다. L 및 a 값은 CPPO에서 더 높았고 b값은 LPPO에서 더 높았다. 이상의 결과를 통해 살균 및 비가열압착한 들깨오일(SRPO)의 무기질 함량, 총 폴리페놀 함량, ABTS 라디칼 소거활성 및 아질산 소거능이 있음을 확인하였다. 또한 시간이 경과할수록 SRPO는 과산화물가가 낮았고, LPPO는 산가가 유의하게 증가하였다. 따라서 본 연구를 종합해 볼 때, 살균 및 비가열압착한 들기름의 경우 기존의 방식으로 생산된 들기름과 영양소 성분이 유사하였다. 이는 새로운 들기름 제조방법을 제공하는 계기가 되었으며, 이를 통해 들기름의 상품화의 기초가 마련되었다고 판단된다.

• 한국해양학회지
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• 제5권1호
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• pp.14-29
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• 1970

김의 성장과 품질에 대한 환경수질의 중요성은 다시 말할 필요가 없다 김 양식기에 있어서의 환경수질의 변동을 보기 위해 저자의 한 사람은 섬진강 및 낙동강 하구 김밭에 대해 이미 조사한 바 있거니와 이번에는 우리나라 유수의 김 생산지인 완도군하 김밭의 수질을 전보와 같은 방법으로 조사하였다. 조사지점으로서는 완도군 에서대체로 대표적 김밭이라 볼 수 있는 두 지점을 선정하여 1968년 10월부터 1969년 2월까지 매월 대조일에서의 수질변동을 조수의 일조기에 걸쳐 1시간마다 각 성분량을 측정하므로써 조사하였다.

• International Journal of Concrete Structures and Materials
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• 제18권1E호
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• pp.3-9
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• 2006

Five slab specimens with predefined cracks are examined to evaluate the corrosion behavior of epoxy-coated bars in chloride contaminated concrete, using linear polarization method. The test specimens were subjected to alternating weekly cycles of ponding in a salt solution and drying for 48 weeks. Test results show that the current density of the specimen of normal steel bars becomes 0.715 ${\mu}A/cm^2$ indicating that the steel bars are in moderate or high corrosion condition. However, the corrosion rates of the specimens with damaged epoxy-coated bars are significantly below 0.1 ${\mu}A/cm^2$ and the bars appears to be in passive condition. The damaged epoxy-coated bars with a corrosion inhibitor of calcium nitrite showed a corrosion rate of 0.110 ${\mu}m/year$ or 56 percents of the corrosion rate of damaged epoxy-coated specimen without such an inhibitor, 0.195 ${\mu}m/year$. However, the corrosion rates of specimens containing the other two corrosion inhibitors, a combination of amines and esters or mixtures of organic alkenyl dicarboxyl acid salts are quite equivalent to the control specimen. The research technique of linear polarization resistance method has proven itself to be useful in measuring corrosion rates of reinforcement in concrete.

• Computers and Concrete
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• 제26권3호
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• pp.257-273
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• 2020

Concrete bond strength with steel re-bars depends on multiple factors including concrete-steel interface and mechanical properties of concrete. However, the hydration development of cementitious paste, and in turn the mechanical properties of concrete, are negatively affected by cold weather. This study aimed at exploring the concrete-steel bonding behavior in concrete cast and cured under freezing temperatures. Three concrete mixtures were cast and cured at -10 and -20℃. The mixtures were protected using conventional insulation blankets and a hybrid system consisting of insulation blankets and phase change materials. The mixtures comprised General Use cement, fly ash (20%), nano-silica (6%) and calcium nitrate-nitrite as a cold weather admixture system. The mixtures were tested in terms of internal temperature, compressive, tensile strengths, and modulus of elasticity. In addition, the bond strength between concrete and steel re-bars were evaluated by a pull-out test, while the quality of the interface between concrete and steel was assessed by thermal and microscopy studies. In addition, the internal heat evolution and force-slip relationship were modeled based on energy conservation and stress-strain relationships, respectively using three-dimensional (3D) finite-element software. The results showed the reliability of the proposed models to accurately predict concrete heat evolution as well as bond strength relative to experimental data. The hybrid protection system and nano-modified concrete mixtures produced good quality concrete-steel interface with adequate bond strength, without need for heating operations before casting and during curing under freezing temperatures down to -20℃.

• Journal of Microbiology and Biotechnology
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• 제16권5호
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• pp.678-682
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• 2006

To remove nitrate from wastewater, a novel bioelectrochemical denitrification system is introduced. In this proposed system, biological reactions are coupled with reactions on the electrode, whereby the electrons are transferred to the bacterial enzymes via a mediator as an electron carrier. The denitrification reaction was achieved with permeabilized Ochrobactrum anthropi SY509 containing denitrifying enzymes, such as nitrate reductase, nitrite reductase, and nitrous oxide reductase, and methyl viologen was used as the mediator. The electron transfer from the electrode to the enzymes in the bacterial cells was confirmed using cyclic voltammetry. A high removal efficiency of nitrate was achieved when the bioelectrochemical system was used with the permeabilized cells. Furthermore, when the permeabilized cells were immobilized to a graphite felt electrode using a calcium alginate matrix containing graphite powder, a high removal efficiency was achieved (4.38 nmol/min mg cell) that was comparable to the result when using the free permeabilized cells.

• 한국환경과학회지
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• 제18권11호
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• pp.1207-1214
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• 2009

Functional properties of Solanium nigrum-ethanol extract were investigated, nitrite scavenging ability(NSA) and antioxidant activities based on thiobarbituric acid(TBA) value were measured. The contents of potassium in fruit and root, calcium in leaf were the highest mineral components in each parts of Solanium nigrum. Total aromatics contents(TAC) was order of fruit>root>leaf, total flavonoid contents(TFC) in leaf was 6 and 10 times, total phenolic compounds contents(TPC) in leaf was 15 and 30 times of those in fruit and root, respectively, and TFC was high with TPC increase. NSA of leaf-ethanol extract was 61.9% on pH 1.2, 53.5% on pH 3.0, 54.8% on pH 4.0 and 14.3% on pH 6.0, where as NSA of root and fruit-ethanol were considerably low to 3.5~7.9% over pH 1.2~6.0. TBA value of soybean oil with the dosage of leaf-extract showed few differences from control within 3 days, but it fairly decreased with considerable antioxidant effect to 47.6% of the control in 8 days.

• KSBB Journal
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• 제26권2호
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• pp.143-150
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• 2011

The aim of the study was to optimize harvesting method for concentrating microalgae from microalgae mass culture. It is well known that the mass density of microalgae is usually very low and these are small size (5-20 ${\mu}m$) in the culture medium. It is essential that microalgae is harvested and concentrated economically for economical biodiesel production from microalgae. In this study, to determine optimized conditions for microalgae harvesting by chemical flocculation. Flocculation of three algae, Chlorella ellipsoidea, Dunaliella bardawil, and Dunaliella tertiolecta, was performed using various chemical flocculants, such as inorganic flocculants (aluminium sulfate, aluminium potassium sulfate, ferrous sulfate, ferric sulfate, ferric chloride, calcium hydroxide, sodium carbonate, sodium nitrite, and sodium aluminate), organic flocculant (polyacrylamide), and biopolymer flocculants (chitosan and starch). The results indicated that aluminium based inorganic flocculants is suitable for microalgae harvesting such as Chlorella ellipsoidea, Dunaliella bardawil, and Dunaliella tertiolecta. The results also recommended that flocculant doses, agitation speed, agitation time, sedimentation time for economical microalgae harvesting method using chemical flocculants.

• 한국수산과학회지
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• 제55권6호
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• pp.858-866
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• 2022

The present study investigated the chemical composition, and antioxidant and physiological activities of the Korean marine algae, Codium fragile. The solvent extracts from C. fragile were prepared using 70% ethanol, 80% methanol, and distilled water. Based on the general chemical composition, carbohydrate, crude protein, crude lipid, crude ash, and moisture were 74.22%, 16.73%, 0.66%, 4.39%, and 4.00%, respectively. Calcium, magnesium, sodium and potassium were the main minerals. The extraction yield range of the solvent extracts was 3.51-9.76%. The ranges of total polyphenol and flavonoid contents were approximately 10.97-13.76 mg/g and 8.00-8.69 mg/g, respectively. The ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)] radical scavenging activity, reducing power and FRAP (ferric reducing antioxidant power) activities were the highest in the ethanol extract, while methanol extract exhibited the strongest nitrite oxide scavenging activity. On the other hand, tyrosinase, elastase, and xanthine oxidase inhibitory activities of the ethanol and methanol extracts were higher than those of the water extract. Furthermore, the ethanol extract exhibited the highest β-secretase inhibitory activity. The results indicate that C. fragile can be used as an antioxidant and a functional ingredient in food and pharmaceutical products.

• 한국식품위생안전성학회지
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• 제25권4호
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• pp.354-359
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• 2010

본 연구에서는 고들빼기의 기능성 식품으로서 이용 가능성성을 검토하기 위하여 고들빼기의 잎과 뿌리 분말에 대한 일반성분, 무기질, 지방산을 분석하였으며, 메탄올 추출물 및 용매 순차 분획물을 이용하여 총 폴리페놀, 총 플라보노이드 함량, 전자공여능 및 아질산염 소거능을 측정하였다. 고들빼기의 일반성분 분석 결과 수분, 탄수화물, 조단백질, 조지방 및 조회분 함량은 잎에서는 각각 4.3%, 53.9%, 21.6%, 3.5% 및 16.7%였으며, 뿌리에서는 각각 4.8%, 65.9%, 17.4%, 3.2% 및 8.7%로 나타났다. 무기질 함량은 칼륨이 잎에서 4,936.9 mg/100 g, 뿌리에서 2,193.8 mg/100 g으로 가장 많이 함유되어 있었으며, 그 다음으로 칼슘, 마그네슘, 철분 순으로 나타났다. 지방산은 잎에서 23종, 뿌리에서 20종이 함유되어 있었으며, 잎에는 총 포화지방산, 단일불포화지방 및 다가불포화지방산이 각각 4 1.4%, 2.7%, 56.0%였으며, 뿌리에는 각각 45.8%, 7.7%, 46.5%의 조성 비율을 나타내었다. 총 폴리페놀 함량은 잎과 뿌리에서 각각 3,922.4 mg/100 g, 1,898.4 mg/100 g이였으며, 총 플라보노이드는 각각 1,903.2 mg/100 g, 359.8 mg/100 g으로 나타났다. 잎의 용매 분획별 전자공여능은 에칠아세테이트 분획이 94.3%로 가장 높았으며, 다음으로 부탄올, 클로로포름, 물 및 헥산 분획 순으로 나타났으며, 뿌리에서는 에칠아세테이트 분획이 92.9%로 높은 활성을 보였고, 다음으로 클로로포름, 부탄올, 헥산 및 물 분획 순으로 나타났다. 분획별 아질산염 소거능은 잎 추출물의 에칠아세테이트 분획이 45.4%로 가장 높았고, 헥산 분획 23.5%, 부탄올 분획 21.3%, 클로로포름 분획 18.7%, 물 분획 9.1% 순으로 나타났으며, 뿌리 추출물의 에칠아세테이트 분획 28.8%, 클로로포름 분획 15.6%, 부탄올 분획 8.0%, 헥산 분획 3.9% 및 물 분획 1.5% 순으로 나타났다. 이상의 결과로 볼 때 고들빼기는 무기질 및 폴리페놀 함량이 풍부하고, 에칠아세테이트 분획은 항산화 효과가 우수하며 아칠산염 소거 효과를 보여, 기능성 소재로서의 활용이 가능하리라 생각된다.