• 식품보건융합연구
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• 제4권4호
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• pp.10-17
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• 2018

Capsicum frutescen is known in Sudan, is one of the most commonly used pepper species in cooking and in Sudanese folk medicine. The present study was conducted to investigate antimicrobial (bacteria and fungi) and cytotoxicity (Brine Shrimp Lethality Test) of methanolic extract of Capsicum frutescen (fruits). The extract have been tested in the present study to investigate the in vitro potential effects against Gram positive, Gram negative bacteria and fungi. The selected organisms were Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and Candida albicans using the cup plate agar diffusion method. The methanol extract of Capsicum frutescen (fruits) exhibited inhibitory effects against Escherichia coli with zone of inhibition (23 mm) and Klebsiella pneumonia with zone of inhibition (17 mm). The phytochemical screening revealed the presence of Tannins, Saponin, Alkaloids, Anthroquinoles and Terpenoids. The Cytotoxicity of methanolic extract of Capsicum frutescens was $LD_{50}$ $64.68{\mu}g/ml$. The activity and presence of compounds known to be biologically active are a validation for the use of Capsicum as a food ingredient and as a therapeutic element of traditional medicine.

• Corrosion Science and Technology
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• 제15권6호
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• pp.311-313
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• 2016

The anodic dissolution behavior of copper and brass in an electrolyte solution of 0.5M NaCl containing 0.5 mM $NaHCO_3$ was investigated by electrochemical impedance spectroscopy. The Nyquist plots of the copper impedance described a small loop in the high-frequency range and a large locus in the low-frequency range. Additionally, the features of the impedance spectrum of the brass were similar to those of the copper. This indicates that the copper-enriched layer formed on the brass surface due to the selective dissolution of the zinc from the surface. In addition, the rest potential and the anodic polarization curve for each sample were measured in order to discuss the selective dissolution of the zinc from the brass surface.

• International journal of advanced smart convergence
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• 제4권2호
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• pp.38-45
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• 2015

Peer-to-Peer(P2P) systems are generally classified into two categories; hybrid and pure P2P. Hybrid systems have a single central index server keeping the details of shared information, so that undesirable effects such as heavy load on that server and lack of fault-tolerance can be caused. Pure P2P causes the other problems such as message flooding and scalability although it shows high degree of fault-tolerance. Recently, mobile agent-based distributed computing has been receiving wide attention for its potential to support disconnected operations, high asynchrony, and thus saving network bandwidth. In this paper, a new scheme of peer coordination is proposed for a decentralized P2P network with self-organizing structure. We deployed mobile agents for incorporating the advantages of usage of mobile agents into our P2P network. Proposed P2P network has both advantages of hybrid and pure P2P. The problems of heavy load on the server and lack of fault-tolerance are improved by using multiple special peers called super-peers. And the problems of pure P2P can be reduced by using mobile agents.

• 자원리싸이클링
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• 제25권3호
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• pp.55-62
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• 2016

해양환경 및 공장지역과 같이 가혹한 부식환경에 놓인 강구조물은 사용수명을 증대시키기 위하여 다양한 방식 기술을 적용하여 건설되고 있다. 그 중 금속용사에 의한 방식기술은 일반적으로 널리 쓰이는 기술의 단점을 보완한 방식 기술이지만 완벽하다 할 수 없어 내식성 향상에 대한 연구개발이 절실한 상황이다. 본 연구에서는 금속용사에서 사용되는 금속 재료의 종류 및 용사 두께의 변화에 따른 내식성을 평가하였으며 전기화학적 방법인 부식전위 및 부식전류밀도 측정을 통하여 비교 고찰하였다. 금속용사 재료로는 아연(Zn) 및 알루미늄(Al)을 사용하여 비율을 조절하였고, 용사 두께는 $30{\sim}100{\mu}m$ 사이에서 구분하여 선정하였다. 검토 결과, 금속용사 재료로 Zn을 100% 사용한 경우에서 가장 낮은 부식전위가 측정된 것을 확인하였으며, Zn 85%-Al 15% 합금과 Al 100%의 경우에는 부식전류밀도가 감소하였다. 또한 용사재료에 관계없이 용사두께가 증가할수록 부식전위는 감소하였다.

• International Journal of Quality Innovation
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• 제6권3호
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• pp.173-189
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• 2005

A life-cycle assessment (LCA) is based on the attention given to the environmental protection and concerning the possible impact while producing, making, and consuming products. It includes all environmental concerns and the potential impact of a product's life cycle from raw material procurement, manufacturing, usage, and disposal (that is, from cradle to grave). This study assesses the environmental impact of the ultra pure water process of semiconductor manufacturing by a life-cycle assessment in order to point out the heavy environmental impact process for industry when attempting a balanced point between production and environmental protection. The main purpose of this research is studying the development and application of this technology by setting the ultra pure water of semiconductor manufacturing as a target. We evaluate the environmental impact of the Precoat filter process and the Cation/Anion (C/A) filter process of an ultra pure water manufacturing process. The difference is filter material used produces different water quality and waste material, and has a significant, different environmental influence. Finally, we calculate the cost by engineering economics so as to analyze deeply the minimized environmental impact and suitable process that can be accepted by industry. The structure of this study is mainly combined with a life-cycle assessment by implementing analysis software, using SimaPro as a tool. We clearly understand the environmental impact of ultra pure water of semiconductor used and provide a promotion alternative to the heavy environmental impact items by calculating the environmental impact during a life cycle. At the same time, we specify the cost of reducing the environmental impact by a life-cycle cost analysis.

• Corrosion Science and Technology
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• 제12권1호
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• pp.40-49
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• 2013

Effects of magnesium and pH on corrosion of aluminum galvanically coupled to iron have studied by using potentio- dynamic and static tests for polarization curves, Mott-Schottky test for analysis of semiconductor property, and GD-AES and XPS for film analysis. Pitting potential was sensitive to magnesium as an alloying element but not to pH, while passive current was sensitive to pH but not to magnesium. It was explained with, instead of point defect model (PDM), surface charge model describing that the ingression of chloride depends on the state of surface charge and passive film at film/solution interface is affected by pH. In addition, galvanic current of aluminum electrically coupled to iron was not affected by magnesium in pH 8.4, 0.2M citrate solution but was increased by magnesium at the solution of pH 9.1. The galvanic current at pH 9.1 increased with time at the initial stage and after the exposure of about 200 minute, decreased and stabilized. The behavior of the galvanic current was related with the concentration of magnesium at the surface. It agreed with the depletion of magnesium at the oxide surface by using glow discharge atomic emission spectroscopy (GD-AES). In addition, pitting potential of pure aluminum was reduced in neutral pH solution where chloride ion maybe are competitively adsorbed on pure aluminum. It was confirmed by the exponential decrease of pitting potential with log of [$Cl^-$] around 0.025 M of [$Cl^-$] and linear decrease of the pitting potential. From the above results, unlike magnesium, alloying elements with higher electron negativity, lowering isoelectric point (ISE), are recommended to be added to improve pitting corrosion resistance of aluminum and its alloys in neutral solutions as well as their galvanic corrosion resistance in weakly basic solutions.

• Nuclear Engineering and Technology
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• 제23권3호
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• pp.321-327
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• 1991

가돌리니아 첨가 우라니아에 대한 점결함 모델이 순수 우라니아의 점결함구조를 바탕으로 하여 개발되었다. Gd 도펀트는 금속이온자리에 -1 유효전하를 지니고, 주위의 산소침입형을 밀어내어 산소침입형의 자리를 감소시킨다. 산소 공공 농도가 증가하면 Gd 도펀트는 산소공공과 집합체를 형성하게 된다. 이 점결함 모델은 Gd 도펀트의 양의 증가에 따른 산소포텐샬의 증가와 산소 대금추비율이 2일때 급속한 산소포텐샬 변화를 설명하여, 현존하는 실험값과 좋은 일치를 보였다.

• 상하수도학회지
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• 제19권4호
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• pp.437-445
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• 2005

Zeta potential is a key parameter of double layer repulsion for individual particles and can usually be used to interpret the trend of coagulation efficiency. This study focused on the measurement of zeta potential of algae and clay under various experimental conditions including water characteristics (pure water, stream water, reservoir water) and coagulant dose (10~50 mg/L). Results showed that the variation of zeta potential was highly sensitive depending on the water characteristics and coagulation conditions. Zeta potential of two genera of algae (anabaena sp. and microcystis sp.) were changed highly with coagulant dosage, especially. On the basis of trajectory analysis, bubble-floc collision efficiency simulated in terms of zeta potential was fitted well with removal efficiency of chlorophyll-a from algae particles. It was found that the control of zeta potential was important for effective removal of algae particles.

• 대한금속재료학회지
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• 제49권6호
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• pp.425-439
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• 2011

A review of the development history of interatomic potential models for ionic materials was carried out paying attention to the way of future development of an interatomic potential model that can cover ionic, covalent and metallic bonding materials simultaneously. Earlier pair potential models based on fixed point charges with and without considering the electronic polarization effect were found to satisfactorily describe the fundamental physical properties of crystalline oxides (Ti oxides, $SiO_2$, for example) and their polymorphs, However, pair potential models are limited in dealing with pure elements such as Ti or Si. Another limitation of the fixed point charge model is that it cannot describe the charge variation on individual atoms depending on the local atomic environment. Those limitations lead to the development of many-body potential models(EAM or Tersoff), a charge equilibration (Qeq) model, and a combination of a many-body potential model and the Qeq model. EAM+Qeq can be applied to metal oxides, while Tersoff+Qeq can be applied to Si oxides. As a means to describe reactions between Si oxides and metallic elements, the combination of 2NN MEAM that can describe both covalent and metallic elements and the Qeq model is proposed.

• 한국표면공학회지
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• 제48권2호
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• pp.68-72
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• 2015

The corrosion behavior of metals and alloys for the safety of offshore structures in seawater was investigated for the application of sacrificial anodes. The experiments were focused on the polarization behaviors and the surface morphology of each metal after experiments. Pure Zn, pure Al (Al1050), Al alloys (Al5052, Al6061), Mg alloys (AZ31, AZ91D) and steel (SCM440) were assessed in 3.5% sodium chloride solution by means of potentiodynamic polarization to verify the galvanic corrosion potential ($E_{couple}$). Potentiostat plots were plotted to compare the surface and corrosion current density ($i_{couple}$) of metals as sacrificial anodes in seawater to protect steel alloy as a cathode. Al alloys showed the best performance as a sacrificial anode, on the other hand, Mg alloys showed overprotection behavior. The surface morphologies of sacrificial anodes were observed by FESEM and compared.