• Title/Summary/Keyword: 반전위

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Relationship between Half Cell Potential and Corrosion Amount Considering Saturated Cover depth and W/C ratios in Cement Mortar (습윤상태의 피복두께와 물-시멘트비를 고려한 반전위와 철근 부식량의 상관성)

  • Ryu, Hwa-Sung;Park, Jae-Sung;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.3
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    • pp.19-26
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    • 2017
  • Concrete is a construction material with porous media and corroded steel inside affects negatively to durability and structural safety. This study aims a derivation of quantitative relationship between measured HCP (Half Cell Potential) and corrosion amount considering cover depth and W/C (water to cement) ratio. For the work, cement mortar specimens with 3 different W/C ratios and 4 different cover depths are prepared, HCPs are measured with 3 different corrosion level. HCP measurement significantly increases in the saturated condition and linear relationship is observed between corrosion level and acceleration period. With increasing corrosion level and W/C ratio, and decreasing cover depth, HCP measurement increases. Considering total corrosion level and HCP measurements, relatively low COV(Coefficient of Variation) of 0.67 is evaluated through multi-linear regression analysis, however higher COVs over 0.90 can be obtained considering level of HCP measurement. In the room condition, corrosion level can be evaluated through measured HCP in the given conditions of cover depth, W/C ratio. diameter of steel inside.

Variation of Half Cell Potential Measurement in Concrete with Different Properties and Anti-Corrosive Condition (콘크리트 특성에 따른 반전위 측정값의 변화와 부식제어 조건)

  • Kim, Ki-Bum;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.6
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    • pp.95-103
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    • 2013
  • Half Cell Potential (HPC) technique has been widely adopted for its quantitative evaluation of corrosion possibility. In this study, RC specimens with three different cover depths (10mm, 30mm, and 60mm) and w/c ratios (0.35, 0.55, and 0.70) are prepared and accelerated salt spray test (SST) is performed for 45 days. Steel corrosion occurs in the specimens with 0.55 of w/c and 10mm of cover depth. In the case of 0.70 of w/c and 30mm of cover depth, steel corrosion is also monitored. Considering the effect of cover depth and w/c ratio, HCP evaluation equation is proposed and the condition which can control steel corrosion is obtained. Furthermore, anti-corrosive conditions containing w/c ratio and cover depth are analyzed through Life 365 program and the conditions are compared with the results from this study.

Numerical Investigation of the Effect of Spacing in Coaxial Propeller Multi-Copter in Hovering (멀티콥터용 동축반전 프로펠러 상하 간격에 따른 제자리 비행 공력 특성에 대한 수치적 연구)

  • Sim, Min-Cheol;Lee, Kyung-Tae;Kim, Hae-Dong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.48 no.2
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    • pp.89-97
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    • 2020
  • In this study, a numerical analysis was performed on 26 inch single and coaxial propeller using the ANSYS Fluent 19.0 Solver to analyse the effect of the distance between coaxial propellers as one of the design parameter. The Moving Reference Frame (MRF) method was used for single propeller, while the sliding mesh method was used for a coaxial propeller to analyse the flow field varying with azimuth angle. The thrust and power are decreased as the upper and lower propeller approaching each other. As H/D is increased, interference between the propellers is decreased. According to the flow field variable contour of the coaxial propeller, it appears that the change in aerodynamic performance is due to the loading effect and the tip vortex wake effect.

The Condition Evaluation of Mortar Parts of Stupa of State Preceptor Jigwang from Wonju Beopcheonsa Temple Site by Half Cell Potential Measurement - with Focus on the Mortar Parts the RoofStone - (반전위 측정을 통한 원주 법천사지 지광국사탑 모르타르 복원부위 상태평가 연구 - 옥개석 모르타르 복원부위를 중심으로 -)

  • Lee, Tae Jong;Cho, Ha Jin;Park, Hee Jeong;Chae, Seung A
    • Journal of Conservation Science
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    • v.34 no.6
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    • pp.503-515
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    • 2018
  • Stupa of State Preceptor Jigwang at Beopcheonsa temple site, Wonju, was conserved and restored in 1957. It was necessary to assess the degree of damage to the used mortar and to provide objective data on the necessity of its removal. Therefore, the HCP(half-cell potential) measurement used in concrete fields was applied. Multi-regression analysis of HCP data, following the rapid corrosion test of the roofstone mortar used by the rebar, resulted in a high correlation of HCP values(0.86), depending on the amount of corrosion and cover depth used for the steel bar. As a result, high correlation values(0.86) for the coefficients of determination were derived. The showed that the measurement of the wet conditions -431 to -663 mV on the roofstone indicated a corrosion damage rate of 90% or more after removal and restoration.

Evaluation of Half Cell Potential Measurement in Cracked Concrete Exposed to Salt Spraying Test (염해에 노출된 균열부 콘크리트의 반전위 평가)

  • Kim, Ki-Bum;Park, Ki-Tae;Kwon, Seung-Jun
    • Journal of the Korea Concrete Institute
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    • v.25 no.6
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    • pp.621-630
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    • 2013
  • Several techniques for steel corrosion detection are proposed and HCP (half cell potential) technique is widely adopted for field investigation. If concrete has cracks on surface, steel corrosion is rapidly accelerated due to additional intrusion of chloride and carbon dioxide ions. This study is for an evaluation of HCP in cracked concrete exposed chloride attack. For this work, RC (reinforced concrete) beams are prepared considering 3 w/c ratios (0.35, 0.55, and 0.70) and several cover depths (10~60 mm) and various crack widths of 0.0~1.0 mm are induced. For 35 days, SST (salt spraying test) is performed for corrosion acceleration, and HCP and corrosion length of rebar are evaluated. With increasing crack width, w/c ratios, and decreasing cover depth, HCP measurements increase. HCP evaluation technique is proposed considering the effects of w/c ratios, crack width, and cover depth. Furthermore anti-corrosive cover depths are obtained through Life365 program and the results are compared with those from this study. The results shows relatively big difference in cracked concrete, however provide similar anti-corrosive conditions in sound concrete.

Detection of Radial Pulse Wave by Photoplethysmogram (광전용적맥파를 이용한 요골동맥 맥파 검출)

  • 정동근;김광년;연규선;최병철;서덕준
    • Journal of Life Science
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    • v.13 no.1
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    • pp.42-46
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    • 2003
  • Photoplethysmogram is widely used to measure heart rate and arterial blood oxygen saturation in human. This paper describes radial pulse waves recorded by photoplethysmogram with 940 nm wavelength infra red light. Radial pulse waves were varied according to the recording site. When recorded on the skin over radial artery, the radial pulse wave was inverted, comparing to the photoplethysmogram at fingertip. The mechanism of inverted pulse wave seemed to be caused by the change of the blood volume in the subcutaneous tissue between radial artery and the skin, which was reduced during systolic period and increased during diastolic period of the cardiac cycle. These results suggest that radial arterial wall may reflect infra red ray.

Relationship between Corrosion in Reinforcement and Influencing Factors Using Half Cell Potential Under Saturated Condition (습윤 상태에서의 반전위를 이용한 철근 부식과 영향 인자 간의 상관성 분석)

  • Jeong, Gi-Chan;Kwon, Seung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.2
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    • pp.191-199
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    • 2021
  • In this study, the correlation between the influencing factors on corrosion and Half Cell Potential(HCP) measurement was analyzed considering the three levels of W/C ratio, cover depth, and chloride concentration. The HCP increased with enlarged cover depth, so it was confirmed that the increment of cover depth was effective for control of corrosion. Based on the criteria, the case of 60mm cover depth showed excellent corrosion control with under -200mV, indicating increase of cover depth is an effective method for reducing intrusion of external deterioration factors. When fresh water was injected to the upper part of specimens, very low level of HCP was monitored, but in the case that concentrations of chloride were 3.5% and 7.0%, HCP dropped under -200mV. In addition, the case with high volume of unit binder showed lower HCP measurement like increasing cover depth. Multiple regression analysis was performed to evaluate the correlation between the corrosive influence factors and HCP results, showing high coefficient of determination of 0.97. However, there were limitations such as limited number of samples and measuring period. Through the additional corrosion monitoring and chloride content evaluation after dismantling the specimen, more reasonable prediction can be achieved for correlation analysis with relevant data.

The Study of Model for Reducing Inversion in RT- Mach (RT- Mach에서 우선순위 반전을 줄이기 위한 모델 연구)

  • Choi, Dae-Soo;Im, Jong-Kyu;Lee, Tea-Hyun;Koo, Yong-Wan
    • Proceedings of the Korean Information Science Society Conference
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    • 1998.10a
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    • pp.98-100
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    • 1998
  • 실시간 시스템은 서버와 같은 공유자원들에 대해서 보다 높은 우선순위 활동의 최악 블록시간(worst case blocking time)을 결정해야한다. 현재까지 분산 시스템을 위한 여러 서버 모델들이 제안되었으며 이러한 서버모델들에 우선순위 규약을 적용하여 실시간성을 높이고 있다. 본 논문에서는 RT- Mach에서 실시간성을 향상시키기 위한 새로운 모델을 제시하여 우선순위 반전 문제를 해결하기 위해 동적 스레드 관리자(dynamic thread manager) 를 제안하였다. 기존의 여러 서버 모델들과 달리 서버마다 동적 스레드 관리자를 두어 작업자 그룹내에서 유혹 스레드(idle thread)와 바쁜스레드 (busy thread ) 판별하여 적절한 스레드를 선정, 조정하고 서버로부터의 요구에 대해 최상위 우선순위를 할당하여 서버간의 우선순위 반전을 중이고 실시간성을 향상시키고자 했다.

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The review of Mozi's Theory and practice about Anti-war and Peace (묵자의 반전 평화에 관한 이론과 실천 재조명)

  • Hwang, SeongKyu
    • The Journal of Korean Philosophical History
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    • no.59
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    • pp.191-214
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    • 2018
  • Mozi was a practitioner who suggested the most persuasive theory about the cruelty of war among Chinese thinkers, and was a theorist who applied his theories into reality. In order to do systematic and comprehensive analysis of Mozi's book,'Non-aggression'in which he suggested anti-war and peace theory, we tried to review his theory both theoretical and practical aspects. We examined the theoretical aspects in three different parts. First, the moral basis of Mozi's anti-war peace theory is "Mutual love" in which they love each other and share their mutual benefits. Second, according to Mozi it is clear that those who caused the war as well as those who steal other people's goods should be punish based on the retribution point of view. Third, Mozi demonstrates that war is not profitable from the economic aspects as well. These three aspects are at the core of anti-war peace theory of Mozi. Next, we looked at the case of Mozi's effort to protect the weak countries in reality. His theory of 'Anti-war and Peace' is presented to protect the weaker countries. Finally, we have looked at some of the Mozi's defensive tactics, which is called the best of all in ancient. Through these considerations, it can be guessed how much he tried to narrow the gap between theory and practice. The Mozi's theory of Anti-war and Peace, which has been struggle to establish a peace in reality, still has realistic significance today.

Electron Mobility Model in Strained Si Inversion Layer (응력변형을 겪는 Si 반전층에서 전자 이동도 모델)

  • Park Il-Soo;Won Taeyoung
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.42 no.3 s.333
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    • pp.9-16
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    • 2005
  • The mobility in strained Si inversion layer on $Si_{1-x}Ge_x$ is calculated considering a quantum effect(subband energy and wavefunction) in inversion layer and relaxation time approximation. The quantum effect in inversion layer is obtained by using self-consistent calculation of $Schr\ddot{o}dinger$ and Poisson equations. For the relaxation time, intravalley and intervalley scatterings are considered. The result shows that the reason for the enhancement in mobility as Ge mole fraction increases is that the electron mobility in 2-폴드 valleys is about 3 times higher than that of 4-폴드 valleys and most electrons are located in 2-폴드 valleys as Ge mole fraction increases. Meanwhile, for the phonon-limited mobility the fitting to experimental data, Coulomb and surface roughness mobilities are included in total mobility, Deformation potentials are selected for the calculated effective field, temperature, and Ge mole fraction dependent mobilities to be fitted to experimental data, and then upgraded data can be obtained by considering nonparabolicity in Si band structure.