• 한국안전학회지
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• 제25권6호
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• pp.28-33
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• 2010

Stainless steel is useful material for various industrial facilities such as the nuclear and steam power plant and the heavy chemical industry due to its good corrosion resistance and mechanical properties. However, it has also a large problem that is sensitized in the welding process and its corrosion resistance and mechanical properties decreases by sensitization. Thus, corrosion and corrosion fatigue characteristics of artificially sensitized austenitic STS304 were investigated through the EPR test and corrosion fatigue test. Obtained results are as follows: 1) According to the sensitizing period increase, Cr deficiency layer is linearly expanded. 2) Degree of sensitization(Ia/Ir) proportionally increased with sensitizing period. However, after 4hrs, it showed constant value. 3) Cr-carbide($Cr_{23}C_6$) in the grain boundary increased as sensitizing period increases until six hours. 4) corrosion fatigue strength of sensitized STS304 were remarkably reduced compare to non-sensitized ones.

• Journal of Plant Biotechnology
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• 제34권3호
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• pp.253-261
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• 2007

본 연구에서는 제초제 저항성 bar 유전자 및 CP4-EPSPS 유전자를 포함하는 발현벡터로 형질전환되고 항생제 마커 유전자를 포함하지 않는 제초제 복합 저항성 감자 식물체를 육성하고자 실험하였다. Bar 유전자를 포함하는 pCAMBIA3300에 CaMV35S 프로모터에 의해 조절되는 CP4-EPSPS 유전자를 도입하여 식물체용 발현 운반체를 제작하고, 이를 Agrobacterium tumafaciens EHA105에 도입하였다. 태동밸리 잎 절편체를 Agrobacterium과 공동배양한 다음, phosphinothricin 0.5 mg/L이 첨가된 배지에서 선발하고 호르몬 무처리 MS발근시켜 형질전환체 (E3-6)를 얻었다. PCR, Southern 분석, 효소면역반응 분석 등을 통해 두 가지 유전자가 도입되었으며 이들이 정상적으로 발현됨이 확인되었다. E3-6 식물체는 glufosinate-ammonium의 어린 식물체 잎 도포처리, glyphosate 용액에 치상한 식물체 조직에서의 shikimate 축적 여부 조사를 통하여 조사한 결과, 두 제초제에 대해 저항성을 나타내었다. 또한 형질전환감자의 전식물체에 대해 glyphosate와 glufosinate-ammonium 각각의 용액 또는 이들의 혼합물을 처리한 후 제초활성 반응을 조사한 결과, E3-6 형질전환 감자는 두 제초제를 각각 단독으로 처리할 때나 혼합하여 동시 처리할 때에도 동일한 저항성이 나타남을 확인하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제17권1호
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• pp.51-55
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• 2016

Phytochemical investigation of Pistacia integerrima has highlighted isolation of two known compounds naringenin (1) and dihydrokaempferol (2). A crude extract and these isolated compounds were here evaluated for their effects on reversion of multidrug resistance (MDR) mediated by P-glycoprotein (P-gp). The multidrug resistance P-glycoprotein is a target for chemotherapeutic drugs from cancer cells. In the present study rhodamine-123 exclusion screening test on human mdr1 gene transfected mouse gene transfected L5178 and L5178Y mouse T-cell lymphoma cells showed excellent MDR reversing effects in a dose dependent manner. In-silico molecular docking investigations demonstrated a common binding site for Rhodamine123, and compounds naringenin and dihydrokaempferol. Our results showed that the relative docking energies estimated by docking softwares were in satisfactory correlation with the experimental activities. Preliminary interaction profile of P-gp docked complexes were also analysed in order to understand the nature of binding modes of these compounds. Our computational investigation suggested that the compounds interactions with the hydrophobic pocket of P-gp are mainly related to the inhibitory activity. Moreover this study s a platform for the discovery of novel natural compounds from herbal origin, as inhibitor molecules against the P-glycoprotein for the treatment of cancer.

• 한국표면공학회지
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• 제51권2호
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• pp.116-125
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• 2018

Aluminum-doped zinc oxide (AZO) is a commonly used material for the front contact layer of chalcopyrite $CuInGaSe_2$ (CIGS) based thin film solar cells since it satisfies the requisite optical and electrical properties with low cost and abundant elemental availability. Low-resistivity and high-transmission front contacts have been developed for high-performance CIGS solar cells, and nearly meet the required performance. However, the durability of the cell especially for the corrosion resistance of AZO films has not been studied intensively. In this work, AZO films were prepared on Corning glass 7059 substrates by radio frequency magnetron sputtering depending on the hydrogen content. The electrical and optical properties and electrochemical corrosion resistance of the AZO films were evaluated as a function of the hydrogen content. With increasing hydrogen content to 6 wt%, the crystallinity, crystal size, and surface roughness of the films increased, and the resistivity decreased with increased carrier concentration, Hall mobility, oxygen vacancies, and $Zn(OH)_2$ binding on the AZO surface. At a hydrogen content of 6 wt%, the corrosion resistance was also relatively high with less columnar morphology, shallow pore channels, and lower grain boundary angles.

• 상하수도학회지
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• 제31권5호
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• pp.389-395
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• 2017

In this paper, we investigate the characteristics of membrane fouling caused by water temperature in the Membrane bioreactor(MBR) process and try to derive the membrane fouling control by chemical enhanced backwashing(CEB). The extracellular polymeric substances(EPS) concentration was analyzed according to the water temperature in the MBR, and the membrane fouling characteristics were investigated according to the conditions, with sludge & without sludge, through a lab-scale reactor. As shown in the existing literature the fouling resistance rate was increased within sludge with the water temperature was lowered. However, in the lab-scale test using the synthetic wastewater, the fouling resistance increased with the water temperature. This is because that the protein of the EPS was more easily adsorbed on the membrane surface due to the increase of entropy due to the structural rearrangement of the protein inside the protein as the water temperature increases. In order to control membrane fouling, we tried to derive the cleaning characteristics of CEB by using sodium hypochlorite(NaOCl). We selected the condition with the chemicals and the retention time, and the higher the water temperature and the chemical concentration are the higher the efficiencies. It is considered that the increasing temperature accelerated the chemical reaction such as protein peptide binding and hydrolysis, so that the attached proteinaceous structure was dissolved and the frequency of the reaction collision with the protein with the chemical agent becomes higher. These results suggest that the MBRs operation focus on the fouling control of cake layer on membrane surface in low temperatures. On the other hand, the higher the water temperature is the more the operation strategies of fouling control by soluble EPS adsorption are needed.

• 아시안잔디학회지
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• 제24권2호
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• pp.170-175
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• 2010

우리나라 16개 골프장으로부터 동전마름병균 24균주를 분리하였다. Sclereotiona homoeocarpa 24 균주의 약제 저항성 검정은 지오판수화제(benzimidazole계)와 테부코나졸유제(demethylation inhibitor: DMI), 이프로디온수화제(dicaboximide계)가 첨가된 영양배지 위에서 균사 생장에의해 결정되었다. 시험결과 24 균주 중 이프로디온수화제에 약제 저항성 발생률은 83.3%, 지오판수화제 62.5%, 테부코나졸유제 0%를 나타냈었다. 또한 이프로디온수화제와 지오판수화제 두 약제에 대한 약제 저항성 발생률은 58.3%였다. 지오판수화제와 이프로디온수화제의 살균제 저항성 발생률은 잔디 초종과 병원균 분리장소와 상관이 없었다. 동전마름병 방제를 위한 포장시험에서 프로사이미돈(prcymidone), 보스칼리드(boscalid), 플루퀸코나졸+테부코나졸(fluquinconazole+pyrimethanil)이 크리핑벤트그래스의 동전마름병을 효과적으로 방제하였다.

• International Journal of Concrete Structures and Materials
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• 제9권2호
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• pp.241-254
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• 2015

A lot of reinforced concrete (RC) structures in Syria went out of service after a few years of construction. This was mainly due to reinforcement corrosion or chemical attack on concrete. The use of blended cements is growing rapidly in the construction industry due to economical, ecological and technical benefits. Syria is relatively rich in scoria. In the study, mortar/concrete specimens were produced with seven types of cement: one plain Portland cement (control) and six blended cements with replacement levels ranging from 10 to 35 %. Rapid chloride penetration test was carried in accordance with ASTM C 1202 after two curing times of 28 and 90 days. The effect on the resistance of concrete against damage caused by corrosion of the embedded steel has been investigated using an accelerated corrosion test by impressing a constant anodic potential. The variation of current with time and time to failure of RC specimens were determined at 28 and 90 days curing. In addition, effects of aggressive acidic environments on mortars were investigated through 100 days of exposure to 5 % $H_2SO_4$, 10 % HCl, 5 % $HNO_3$ and 10 % $CH_3COOH$ solutions. Evaluation of sulfate resistance of mortars was also performed by immersing in 5 % $Na_2SO_4$ solution for 52 weeks. Test results reveal that the resistance to chloride penetration of concrete improves substantially with the increase of replacement level, and the concretes containing scoria based-blended cements, especially CEM II/B-P, exhibited corrosion initiation periods several times longer than the control mix. Further, an increase in scoria addition improves the acid resistance of mortar, especially in the early days of exposure, whereas after a long period of continuous exposure all specimens show the same behavior against the acid attack. According to results of sulfate resistance, CEM II/B-P can be used instead of SRPC in sulfate-bearing environments.

• Journal of Advanced Marine Engineering and Technology
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• 제31권2호
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• pp.173-181
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• 2007

Recently, galvanizing method is predominantly being used not only a economical point of view but also due to it s stability and long life. For example, guard rail of high way, all kinds of structures for ship etc. were protected with galvanizing and demand of galvanized structural materials was being increased with more and more. However, galvanized structures were inevitably being deteriorated with time eventually because they were corroded with solution of galvanizing film and exfoliation of it s film in the present severe corrosive environment. Therefore, it is necessary to improve the corrosion resistance of the galvanizing film through various methods such as variation of chemical composition of galvanizing bath, chromate treatment and coating treatment. In this study, three test specimens such as pure galvanizing, galvarium, and chromate treatment were submerged at tap water with inhibitor addition. And the effect of their corrosion resistance improvement was comparatively investigated with electrochemical method. Corrosion current density of the galvanized steel was the largest among three specimens, however, the galvarium steel showed the lowest corrosion current density. Futhermore, these three kinds of test specimens indicated considerably excellent corrosion resistance by dipped at tap water with inhibitor addition. Especially, the galvanized steel showed the best effect of corrosion resistance improvement than other test specimens.

• Korean Chemical Engineering Research
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• 제61권1호
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• pp.26-31
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• 2023

고분자 전해질 연료전지(Polymer electrolyte membrane fuel cell, PEMFC) 고분자막의 내구성 향상을 위해서 빠른 시간에 내구성을 평가할 수 있는 가속 내구 평가법들이 연구 개발되었다. 그러나 트럭, 버스 등 대형 상용차용 연료전지 수명은 승용차보다 3배 이상 요구되어 화학적 가속 내구 평가(Accelerated stress test, AST) 시간도 길어져서 1,500 시간 이상이 되었다. 그래서 본 연구에서는 단 시간내에 고분자막의 화학적 내구성을 평가하기 위한 방법으로 막 초기 특성으로 내구성을 예측할 수 있을지 검토하였다. 초기 특성으로 수소투과전류밀도(Hydrogen crossover current density, HCCD)와 단락 저항(Short resistance, SR)을 그리고 3시간의 셀 밖 실험으로 가능한 Fenton 실험을 통해 AST 시간을 예측하였다. HCCD와 불소 이온 유출 농도가 증가하면 AST 시간이 선형적으로 짧아지는 경향을 보였으나 편차가 있었다(R² ≒0.65). SR이 감소하면 AST 시간이 선형적으로 증가하는 상관관계를 보였으며 정확도가 높아(R² =0.93) 고분 자막 초기 SR로 AST 시간을 예측할 수 있었다.

• 한국지반신소재학회논문집
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• 제3권1호
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• pp.37-42
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• 2004

보강토 옹벽시스템에서, 부직포 지오텍스타일은 블럭이 시공될 때 보강토체의 전면에 노출, 포설되어 있다. 임시구조물에 보강토 옹벽이 적용될 때 지오텍스타일은 시공기간 중 일광에 노출되게 된다. 이 기간 중, 자외선에 의해 부직포 지오텍스타일의 분해가 발생하게 된다. 따라서 현장시공의 관점에서 부직포 지오텍스타일의 자외선 저항성이 명확하게 평가되어야만 한다. 본 연구에서는 실험실 및 현장시험을 수행하여 KOESWall 시스템에 사용되는 부직포 지오텍스타일의 자외선 저항성이 평가되었고, 그 결과를 SEM 사진과 인장특성으로 나타내었다.