• Title/Summary/Keyword: cyclic humidity

Search Result 6, Processing Time 0.05 seconds

Analysis of Chloride Ion Penetraion for Marine Concrete Structure with Cyclic Humidity Environment (건습이 반복되는 환경하의 해양콘크리트 구조물에 대한 염소이온 침투 해석)

  • Han, Sang-Hun
    • Ocean and Polar Research
    • /
    • v.26 no.1
    • /
    • pp.43-50
    • /
    • 2004
  • The diffusion model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion model provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in situ analysis of chloride ion penetration for marine concrete structures must be performed considering the cyclic humidity condition and the long term sorption.

The preliminary study of developing strong corrugated box board against aggravated service condition(I) (환경변화에 강한 골판지 개발을 위한 기초연구(제1보))

  • 서영범;오영순
    • Journal of Korea Technical Association of The Pulp and Paper Industry
    • /
    • v.30 no.1
    • /
    • pp.29-43
    • /
    • 1998
  • This study was to investigate the effect of .compressive load and cyclic humidity(2$0^{\circ}C$, 65% and 90% RH) on the physical and mechanical properties of corrugated board. Corrugated boards in the study were under compressive load and under cyclic humidity, and their properties were compared to those without load. Results were summarized as follows ; 1 Statistically significant correlation was shown between the ring crush of the boards and the compressive strength of cylinder specimen made from the boards. So we could study the compressive behavior of board with cylinder specimen. 2. The boards under the compressive load increased their moisture content and thickness much more than those without load both in constant and in cyclic RH. 3. The compressive and tensile strength of board samples were inversely and closely proportional to the sheet moisture content regardless of their load and humidity history. 4. The moisture content did not show any significant proportionality to the change of burst strength of boards within this experiment. 5. Board reconditioning in standard condition led to the recovery of the strength loss that had occurred under various load and humidity condition. 6. The handsheets prepared from the boards that had experienced compressive load and cyclic humidity, and those with no-load and 65% RH did not show any significant difference in strength properties. No physical damage or load-carrying properties of the wood fiber were observed by the compressive load and cyclic humidity history.

  • PDF

Analysis of Chloride Ion Penetration for Harbor Concrete Structure with In-situation Environment (항만 콘크리트 구조물의 현장환경변화에 따른 염소이온 침투해석)

  • Han, Sang-Hun;Jang, In-Sung
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2004.11a
    • /
    • pp.225-228
    • /
    • 2004
  • In order to estimate the chloride ion penetration, the model, which considers diffusion and sorption, is proposed on the basis of Finite Element Method (FEM). The FEM program provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages and constant outer humidity, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in-situ analysis of chloride ion penetration for marine concrete structures must be performed considering the cyclic humidity condition and the long term sorption.

  • PDF

Analysis of Chloride ion Penetration for In-Situation Harbor Concrete Structures (현장 항만 콘크리트 구조물에 대한 염소이온 침투 해석)

  • Han Sang-Hun
    • Journal of the Korea Concrete Institute
    • /
    • v.17 no.5 s.89
    • /
    • pp.751-760
    • /
    • 2005
  • The chloride penetration model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion and sorption model provides the estimation of chloride concentration variation according to cyclic humidity and temperature. The humidity diffusion analysis is carried out, and the chloride ion diffusion and sorption analysis are conducted on the basis of the pre-estimated humidity data in each element. Each element has different variables at different ages and locations in analysis. At early ages, the difference of relative humidity between inner and outer concretes causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference of relative humidity between inner md outer concretes with age, the effect of sorption on the chloride ion penetration decreases with age. The cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and increases the quantity of chloride ion around steel at later ages. Therefore, the in-situ analysis of chloride ion Penetration for harbor concrete structures must be Performed considering the cyclic humidity conditionandthelongtermsorption.

A New Compressive Testing Specimen for Linerboard and Corrugating Medium (ECT를 응용한 라이너지의 압축강도 측정시편 개발)

  • Youn, Seuk-Ki;Seo, Yung-Bum;Jeon, Yang
    • Korean Journal of Agricultural Science
    • /
    • v.35 no.1
    • /
    • pp.19-24
    • /
    • 2008
  • A new compressive strength test specimen for linerboard and medium was developed, and tested for its agreement with conventional testing methods such as RCT and STFI. The new specimen enables compressive testing under the changing humidity and temperature. Experimental results showed that the new specimen gave equivalent compressive strengths as the other conventional methods at a constant temperature and humidity. We'll apply the methods under the cyclic humidity and temperature conditions.

  • PDF

The humidity sensitive characteristics of $CaZrO_3$ ceramics ($CaZrO_3$ 세라믹스의 감습 특성)

  • Yuk, Jae-Ho;Kim, Yong-Woon
    • 전자공학회논문지 IE
    • /
    • v.43 no.3
    • /
    • pp.1-5
    • /
    • 2006
  • [ $CaZrO_3$ ] humidity sensors were prepared using the solid-state synthetic method and their humidity sensitive characteristics have been investigated. It was found that the impedance of the humidity sensors decreased with increasing relative humidity and the humidity sensitivity depended on the applied frequencies. The sensitivity of sensor is stable with heat treatment and a negligible hysteresis under cyclic humidity changes is shown, and the activation energy for electrical conduction is reduced with water adsorption.