• 제목/요약/키워드: cyclic humidity

검색결과 6건 처리시간 0.132초

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

  • 한상훈
    • Ocean and Polar Research
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    • 제26권1호
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    • pp.43-50
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    • 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.

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

  • 서영범;오영순
    • 펄프종이기술
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    • 제30권1호
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    • pp.29-43
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    • 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.

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

  • 한상훈;장인성
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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    • pp.225-228
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    • 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.

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

  • 한상훈
    • 콘크리트학회논문집
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    • 제17권5호
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    • pp.751-760
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    • 2005
  • 본 논문에서는 확산과 수분이동에 의한 침투를 함께 고려할 수 있는 염소이온침투 모델을 제시하고 이를 바탕으로 유한요소 프로그램을 개발한다. 개발된 프로그램을 이용하여 습도와 온도가 연속적으로 변화하는 현장상태에 대한 염소이온 침투 해석을 수행한다. 해석과정으로 먼저 수분확산해석을 수행한다. 이 해석에 의한 각 유한요소의 상대습도를 바탕으로 염소이온 침투해석을 위한 재료상수를 구한다. 이러한 재료상수를 이용하여 염소이온 침투해석을 수행하게 된다. 각 유한요소들은 시간과 재령에 따라 연속적으로 변화하는 재료상수 값을 가지게 된다. 내외부의 상대습도 차이가 크면 수분이동에 의한 염소이온 침투의 영향이 커지지만 내외부의 상대습도의 차이는 수분확산에 의해서 재령에 따라 감소하므로 수분이동에 의한 염소이온 침투의 영향은 재령에 따라 감소한다. 반복 습윤은 수분이동에 의한 염소이온 침투의 영향을 증가시켜 철근 주위의 염소이온 농도를 커지게 한다. 현장상황과 같이 건습의 반복이 장기적으로 발생하게 되면 수착과 확산을 함께 고려한 염소이온 침투량이 수분이동을 고려하지 않은 염소이온 침투량보다 매우 크다. 따라서, 항만 콘크리트 구조물에 대한 염소이온 침투해석을 장기재령동안 수행할 경우에는 수분이동 메커니즘을 포함한 수치 모델링을 바탕으로 건습의 반복을 고려하여 해석을 수행하는 것이 해석의 오차를 줄일 수 있을 것이다.

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

  • 윤석기;서영범;전양
    • 농업과학연구
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    • 제35권1호
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    • pp.19-24
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    • 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.

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

  • 육재호;김용운
    • 전자공학회논문지 IE
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    • 제43권3호
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    • pp.1-5
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    • 2006
  • 고상반응법을 이용하여 $CaZrO_3$ 습도센서를 제작하였으며 그의 감습특성에 대하여 연구하였다. 습도센서의 임피던스는 상대습도가 증가함에 따라 감소하며 감습도는 주파수에 의존하였다. 센서의 감습도는 열처리에 안정되고 흡습 탈습에 따른 히스테리시스 현상이 거의 나타나지 않았으며 전기전도 활성화에너지는 흡습에 따라 감소하였다.