• 한국구조물진단유지관리공학회 논문집
• /
• 제5권1호
• /
• pp.188-194
• /
• 2001

A reinforced concrete structure is complex structure that works as one body with bonding role of steel bar and concrete. The bonding action between steel bar and concrete makes possible the compound structure. The transmission of mutual strength of the steel bar with concrete in structure is determined by the bonding characteristic of steel bar and concrete surface. But the efficiency of bonding characteristic of steel bar is Questionable by the corrosion cause by the delay construction term, the wrong management, etc. So this study investigate bonding characteristic of reinforced concrete using pull-out test method which steel bar removed rust and the principal variables of this study are concrete compression strength and the degree of corrosion. The result showed that bonding strength tend to increase when removed rust of steel bar whereas it tend to decrease when not removed rust.

• Corrosion Science and Technology
• /
• 제4권4호
• /
• pp.121-129
• /
• 2005

Basic design concept of the future steel structure requires environmental compatibility and maintenance free capability to minimize economic burdens. Recent trends in alloy design for advanced weathering steel include addition of various alloying elements which can enhance formation of stable and protective rust layer even in polluted urban and/or high $Cl^{-}$ environment. The effects of Ca, Ni, W, and Mo addition on the corrosion property of Ca-modified weathering steel were evaluated through a series of electrochemical tests (pH measurement and electrochemical impedance spectroscopy: EIS) and structural analysis on rust layer formed on the steel surface. Ca-containing inclusions of Ca-Al-Mn-O-S compound are formed if the amount of Ca addition is over 25 ppm. Steels with higher Ca content results in higher pH value for condensed water film formed on the steel surface, however, addition of Ni, W, and Mo does not affect pH value of the thin water film. The steels containing a high amount of Ca, Ni, W and Mo showed a dense and compact rust layer with enhanced amount of ${\alpha}-FeOOH$. Addition of Ni, W and Mo in Ca-modified weathering steel shows anion-selectivity and contributes to lower the permeability of $Cl^{-}$ ions. Effect of each alloying element on the formation of protective rust layer will be discussed in detail with respect to corrosion resistance.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
• /
• pp.308-311
• /
• 1998

Some nondestructive diagnostic methods including various types of corrosion sensors have been investigated. Under these conditions, a new structure of sensor that has a pair of electrode and magneto-supply was proposed. In order to detect the edge of the iron rust part, three-poles touch-type corrosion sensor is now proposed. The iron rust pattern where the sensor touches is estimated by means of the impedance of the sensor, and the edge of the iron rust is recognized by comparing the three measured impedances. As the result, our proposed sensor is useful to detect the initial state of iron rust.

• Journal of Microbiology and Biotechnology
• /
• 제14권2호
• /
• pp.422-425
• /
• 2004

To discover a potent strain against wheat leaf rust, soil samples collected from Ilgamho, Seoul, Korea were tested in vivo and a strain belonging to Streptomyces sp. was found to show good antifungal activity when fermented in a broth. The identification of the strain was carried out based on 16S rDNA analysis, and the active compound was separated from the fermented broth. Even though its structure was not determined completely, the authors report the results obtained so far indicate that the fermented broth of the strain showed activity against wheat leaf rust. Therefore, we propose that this may be a potential novel strain showing antifangal activity against Puccinia recondita.

• 식물병연구
• /
• 제30권1호
• /
• pp.20-25
• /
• 2024

A fungus strain Stereostratum corticioides PKVL1, belonging to the family Pucciniaceae that causes rust in plants, was discovered on the sheath of the bamboo Pseudosasa japonica leading to the death of the infected bamboo in the following year. Microscopic observation of the yellow fungal mass revealed teliospores with an oval, one-septate (two-celled) structure. The average length and width of teliospores were 31.83±3.57 ㎛ and 20.74±1.72 ㎛, respectively. The large-subunit ribosomal RNA gene was amplified using the LR0R and LR7 primers, showing that the strain PKVL1 had a similarity of 99.34% to previously reported S. corticioides. In particular, the two Stereostratum strains form a separate cluster among the fungi in the family Pucciniaceae. This is the first report in the Republic of Korea of fungal rust occurring on the culm of bamboo rather than on the leaves.

• 한국산학기술학회논문지
• /
• 제14권5호
• /
• pp.2063-2068
• /
• 2013

해양환경에서 사용되는 선박이나 해양구조물은 해수환경에서 쉽게 부식이 발생한다. 본 연구에서는 구조용 강재에서 부식생성물의 존재가 피로강도에 미치는 영향에 대하여 조사하였다. 이를 위하여 부식생성물을 제거한 시험편과 부식생성물이 부착된 시험편의 피로강도를 비교하고 부식생성물의 강도분담에 대하여 고찰하였다. 본 연구에서 부식생성물은 피로강도분담효과가 있으며, 부식생성물을 제거한 시험편의 피로강도는 부식생성물이 부착되어 있는 시험편보다 피로강도감소계수가 18.1% 감소하였다. 이상의 연구에서 부식생성물 내에서 강도상 유해물질이 없는 한 부식생성물은 피로강도에 유익함을 알 수 있었다.

• Journal of Nuclear Fuel Cycle and Waste Technology
• /
• 제1권1호
• /
• pp.57-63
• /
• 2013

Natural green rust (GR) can retard the migration of anions through geological media because it has a Layer Double Hydroxyl (LDH) structure with a positive charge. In this study, the sorption behaviors of anions such as selenite ($Se(IV)O{_3}^{2-}$), selenate ($Se(VI)O{_4}^{2-}$), and iodide ($I^-$) onto green rusts with different structures, i.e., GR($Cl^-$) and GR($CO{_3}^{2-}$), were investigated by conducting batch sorption experiments in an anoxic condition. Experimental results showed that selenite was mostly sorbed onto GR($CO{_3}^{2-}$) and then partly reduced to metal selenium, Se(0). However, little selenate and iodide was sorbed onto GR($CO{_3}^{2-}$) while some iodide was sorbed onto GR($Cl^-$). It is presumed from the experimental results that the major sorption mechanism of $SeO{_3}^{2-}$ and $I^-$ onto green rusts is the anion exchange reaction with the anions existing in the interlayer of the rusts. Green rust, therefore, can play an important role in the retardation of anions migrating through deep geological environments owing to its LDH structure with a high anion exchange capacity.

• 콘크리트학회논문집
• /
• 제20권6호
• /
• pp.741-746
• /
• 2008

RC 구조물에서 매립된 철근의 부식을 억제하기 위하여 많은 방법들이 소개되어 왔다. 철근의 부식을 억제하는 방법 중 하나가 부식억제제이다. 최근 탄닌산을 이용하여 활성태의 녹을 부동태의 녹으로 전환시킴으로써 부식의 진행을 지연시키는 기술이 개발되었다. 그러나 이 부식억제제가 일반적인 금속 제품에 대한 방식을 위하여 개발되었기 때문에 콘크리트구조물에 대한 성능이 검토되지 않았다. 따라서 본 연구에서는 탄닌산을 이용한 부식억제제의 적용성을 콘크리트 시험체에 대하여 조사하였다. 연구 결과에 따르면, 탄닌산 부식억제제는 콘크리트에 있어 시공성 및 압축강도의 저하를 발생시키지 않았다. 부식억제제가 시멘트 중량당 4% 이상 첨가될 경우, 염화물 침투깊이가 10% 정도 감소하였다. 또한, 탄닌산 부식억제제는 녹을 안정한 상태로 변환시키는 효과를 가지고 있어, 부식 저항성이 향상된다. 특히, 6% 이상의 첨가가 부식 저항성에 효과적인 것으로 나타났다.

• Computers and Concrete
• /
• 제33권6호
• /
• pp.631-642
• /
• 2024

The present study concerns the corrosion mitigation of electrochemical chloride extraction (ECE) in concrete structure. Concrete specimen was fabricated with 5.0% chloride in cast, while the other specimen was exposed to 4.0M NaCl solution for 1 year to accelerate corrosion of steel. Then, the ECE was applied to the concrete specimen with 1000 mA/m² of the current density for 2, 4 and 8 weeks, respectively. During the ECE, the corrosion current density and corrosion potential were regularly monitored. As a result, the ECE was very effective in mitigating the degree of corrosion on the steel surface. The corrosion current density was significantly reduced from thousands to decades mA/m², while the corrosion potential was mostly shifted to positive direction. Assuming that the corrosion starts at 1.0 mA/m² of the corrosion current density or/and -275 mV vs SCE of the corrosion potential, the ECE could not fully achieve the repassivation of the steel, although its degree was lowered more or less depending on the duration of the treatment and type of chloride contamination. A visual examination confirmed that an increase in the duration of the treatment could lower the rust formation, but never fully removed all rust stains.

• 광물과 암석
• /
• 제35권2호
• /
• pp.111-123
• /
• 2022

본 연구는 자연계에서 가장 흔하게 관찰되는 두 그린 러스트(green rust) 광물인 carbonate green rust (CGR)과 sulfate green rust (SGR)을 공침법(co-precipitation)을 통해 각각 합성하고, 이들의 형성 메커니즘 및 이화학적 특성들을 체계적으로 규명하였다. X-선 회절(XRD) 분석 및 리트벨트 정련 수행 결과, 본 합성 조건에서 이차광물상 없이 이중층수산화물로서 CGR과 SGR이 합성됨을 확인하였다. 또한, 각각의 구조 파라미터는 CGR의 경우 a(=b)축 = 3.17 Å, c축 = 22.52 Å이고, SGR의 경우 a(=b)축 = 5.50 Å, c축 = 10.97 Å이며, 이들의 미결정 크기는 각각 (003)면 기준 57.8 nm와 (001)면 기준 40.1 nm로 밝혀졌다. 주사전자현미경/에너지 분산형 분광분석(SEM/EDS) 결과, CGR과 SGR은 모두 육각 판상의 전형적인 이중층수산화물 결정 형상을 보이지만 탄소(C)와 황(S)의 함량은 서로 다르게 나타났다. 퓨리에 변환 적외선(FT-IR) 분광 분석결과, 탄산염(CO₃^2-)와 황산염(SO₄^2-) 이온들이 각각 CGR과 SGR의 층간 음이온으로 밝혀졌고, 이는 XRD를 활용한 광물상 동정 결과와 잘 일치한다. 철 용액으로의 수산화이온(OH^-) 주입 시간에 따른 혼합 용액의 pH와 Eh, 그리고 잔류 철 농도의 비율(Fe(II):Fe(III)) 측정 결과, 시간에 따른 차이는 있지만 두 green rusts 모두 1단계 전구체 형성, 2단계 중간 생성물로의 상변환, 그리고 3단계 green rust로의 상변환과 에이징에 의한 결정성장으로 이어지는 결정 형성 메커니즘을 보이는 것으로 판단된다. 본 연구는 공침법을 통해 CGR과 SGR을 안정적으로 합성하고 이들의 형성 메커니즘과 이화학적 특성을 규명함으로써, green rust를 활용한 응용 연구 및 산업 활용에 원천 기초자료를 제공할 것으로 기대된다.