• 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.

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.332-337
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• 2004

The use of gas absorption refrigeration machine has considerably increased because of the shortage of the electric power in the summer and the regulation of freon refrigerant. Gas absorption refrigeration machine consists of a condenser, a heat exchanger. supplying pipes, a radiator etc, This system is likely to be corroded by acid. dissolved oxygen and gases, Cavitation erosion-corrosion by flow velocity of cooling water may happen in absorption refrigeration machine. In these cases. erosion and corrosion occur simultaneously. Then, it makes a serious damage with synergy effect. Therefore, this paper was studied on the cavitation damage of cupronickel(70/30) tube for gas absorption refrigeration machine, In the $30^{\circ}C$ tap water, linear polarization test and anodic polarization test were carried out for copper(C1220T-OL) and cupronickel(70/30) tube. Also, cavitation erosion-corrosion behavior of cupronickel (70/30) tube was considered, The main results are as following: (1) In the linear test, the corrosion current density of cupronickel(70/30) is higher than that of copper. (2) The erosion-corrosion rate of cupronickel(70/30) displayed later tendency than that of copper by vibratory cavitation in cooling water. (3) In cooling water, the progress mechanism of erosion-corrosion rate of copper and cupronickel(70/30) follows a pattern of incubation, acceleration, attenuation and a steady state period.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.254-257
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• 2006

Five bench scale specimens were used to evaluate corrosion performance of damaged epoxy-coated bars in chloride contaminated concrete. The test specimens were subjected 48 weekly cycles of ponding with sodium chloride solution and drying. Test results using linear polarization technique show that the current density of specimen with conventional steel 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 much below $0.1\;{\mu}A/cm^2$ and the bars appears to be in passive condition. The corrosion protection performance provided by calcium nitrite is better than that of specimens with the other two inhibitors.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.479-481
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• 2007

COMS will transmit its observed data, Sensor Data, through L-Band with linear polarization. To avoid link loss caused by polarization discrepancy between satellite and SOC DATS, the L-Band antenna at SOC DATS should be linearly polarized. However, SOC DATS is supposed to share single antenna with SOC TTC, so the antenna should be circularly polarized. To cope with about 3dB loss, SOC DATS is designed to receive Sensor Data through two orthogonal circular polarizations, RHCP (Right-Hand Circular Polarization) and LHCP (Left-Hand Circular Polarization). Eventually, SOC DATS can obtain 2.6dB of combining gain through diversity combiner in MODEM/BB. This paper presents the verification on the diversity combining of SOC DATS with test configuration and results in depth.

• Corrosion Science and Technology
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• 제20권2호
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• pp.52-61
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• 2021

This study using experimental design and linear regression technique was implemented in order to predict the pitting potential of stainless steel in marine environments, with the target materials being AL-6XN and STS 316L. The various variables (inputs) which affect stainless steel's pitting potential included the pitting resistance equivalent number (PRNE), temperature, pH, Cl^- concentration, sulfate levels, and nitrate levels. Among them, significant factors affecting pitting potential were chosen through an experimental design method (screening design, full factor design, analysis of variance). The potentiodynamic polarization test was performed based on the experimental design, including significant factor levels. From these testing methods, a total 32 polarization curves were obtained, which were used as training data for the linear regression model. As a result of the model's validation, it showed an acceptable prediction performance, which was statistically significant within the 95% confidence level. The linear regression model based on the full factorial design and ANOVA also showed a high confidence level in the prediction of pitting potential. This study confirmed the possibility to predict the pitting potential of stainless steel according to various variables used with experimental linear regression design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1278-1280
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• 1995

A probe type fiber-optic sensing techique for electric current measurement is applied in this paper. The technique is based on the Faraday effect which meaning is that polarization state of light is rotated by magnetic field. In experiment, test wire is located at inside and outside of the probe to be measured. The experimental results prove not only linear property, but also polarization rotation property according to the distance from outside of probe.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2005년도 공동학술대회 논문집
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• pp.233-236
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• 2005

천부 탄성파 탐사 기록에서 신호부를 약화시키는 레일리파를 제거하고, 초동 인지가 어려운 S파 신호를 강화하는 방법을 제시하고자 다성분 복소트레이스 분석법에 기초한 분극 필터를 작성하였다. 이 분극필터의 효율성을 시험하기 위해서 단순한 수평 2층 모델 자료를 유한차분법으로 합성하였다. 그 결과 타원운동을 하는 레일리파가 비교적 잘 제거되고 선형운동의 P파와 S파도 효과적으로 분리됨을 볼 수 있었다.

• 지구물리
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• 제8권1호
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• pp.35-38
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• 2005

천부 탄성파 탐사 기록에서 신호부를 약화시키는 레일리파를 제거하고, 초동 인지가 어려운 S파 신호를 강화하는 방법을 제시하고자 다성분 복소트레이스 분석법에 기초한 분극필터를 작성하였다. 이 분극필터의 효율성을 시험하기 위해서 단순한 수평 2층 모델 자료를 유한차분법으로 합성하였다. 그 결과 타원운동을 하는 레일리파가 비교적 잘 제거되고 선형운동의 P파와 S파도 효과적으로 분리됨을 볼 수 있었다.

• 대한금속재료학회지
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• 제47권10호
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• pp.635-643
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• 2009

The resistance to pitting corrosion of Fe-Cr alloys was evaluated by performing potentiodynamic polarization and critical pitting temperature (CPT) tests. For the potentiodynamic polarization tests, various standards were applied, i.e., KS D 0238 (wet, dry), ASTM G 61, and ISO 17475, showing different potentiodynamic polarization results including pitting potentials. ASTM G 61 and ISO 17475 standards presented relatively higher pitting potential while KS D 0238 (dry) indicated lower values than the others. Effects of surface roughness, scan rates, and exposure time to air before tests were also investigated. CPT tests were performed under two different applied potentials, 300 m$V_{SCE}$ and 200 m$V_{SCE}$ in deaerated 1 M NaCl aqueous solution. CPT values and the polarization test results showed a linear relationship.

• International Journal of Concrete Structures and Materials
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• 제2권2호
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• pp.99-105
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• 2008

Southern exposure test specimens were used to evaluate corrosion performance of epoxy-coated reinforcing bars in chloride contaminated concrete by electrochemical impedance spectroscopy method. The test specimens with conventional bars, epoxy-coated bars and corrosion inhibitors were subjected 48 weekly cycles of ponding with sodium chloride solution and drying. The polarization resistance obtained from the Nyquist plot was the key parameter to characterize the degree of reinforcement corrosion. The impedance spectra of specimens with epoxy-coated bars are mainly governed by the arc of the interfacial film and the resistance against the charge transfer through the coating is an order of magnitude higher than that of the reference steel bars. Test results show good performance of epoxy-coated bars, although the coatings had holes simulating partial damage, and the effectiveness of corrosion-inhibiting additives. The corrosion rate obtained from the impedance spectroscopy method is equivalent to those determined by the linear polarization method for estimating the rate of corrosion of reinforcing steel in concrete structures.