• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.769-772
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• 2008

공극은 열화인자의 이동경로가 되어 콘크리트의 성능을 저하시키는 요인으로 작용할 수 있으며 수분은 콘크리트 내부의 공극을 충전시킬 수 있기에 수분에 의한 투기성이 시멘트경화체의 공극구조에 미치는 영향을 평가하는 것은 중요하다. 이에, 본 연구에서는 공극구조와 투기성에 대하여 0%, 40%, 60%, 80%, 90%의 습도를 유지시킨 시험체와 화학조성물인 리튬실리케이트를 도포시켰을 경우의 공극구조 변화를 평가하였다. 그 결과, 함수율이 증가할수록 투기성은 저하되고 공극구조의 밀실성이 향상되어 수분에 의한 응축현상을 확인할 수 있었다. 그리고 수용액 상태의 리튬실리케이트는 수분을 함유하고 있는 상태에서 1$\mu$m 전, 후의 공극을 충전시켜 밀실성을 향상시키나함수조건에 따라 침투성에 의한 성능향상 범위가 제한적일 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.705-708
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• 2008

본 연구에서는 규조토, 벤토나이트, 제올라이트를 사용하여 건축내장용 조습패널을 제조하였으며,패널 제조에 사용된 원료의 특성에 따른 조습 성능 등을 평가해 보고자 하였다. 철원 규조토는 형태와 구조가 와해 변질된 상태로 존재하였으며, 포항 벤토나이트는 입자 표면이만곡 현상(彎曲 現狀)과 많은 기공을 관찰할 수 있었다. 제올라이트는 타원형 또는 구형의 형태를 가지고 있으며, 다수의 판상 입자들이 한개의 거대 입자(15$\mu$m 전후)를 형성하는 특징이 있었다. 또한 대부분의 원료들은 판상이거나 침상으로 다공질의 미세구조를 관찰할 수 있었다. 각 원료를 사용해 제조한 조습패널은 다공성 원료의 첨가로 인해 다공성 원료를 혼합하지 않은 패널 보다 수분의 흡방습 특성은 크게 개선되어, 포항 제올라이트 10% 패널의 경우에는 흡습량 180g/m$^2$, 방습량 105g/m$^2$ 수준이었다. 또한 패널의 비표면적 및 기공 부피와 수분 흡방습량과의 높은 상관성이 있음을 확인하였다. 또한 다공성 원료의 종류에 따라서도 패널의 수분 흡방습량은 차이가 있었으며, 이는 다공성 원료의 영향으로 판단되었다. 이때 철원 규조토를 10% 첨가한 패널의 수분 흡습량은 170g/m$^2$ 정도 였으며, 포항 제올라이트를 10% 첨가한 패널의 수분 흡습량은 180g/m$^2$, 방습량은 105g/m$^2$ 로 다공성 원료를 혼합하지 않은 패널(흡/방습량:80/40g/m$^2$) 보다 매우 우수한 흡방습능을 나타내었다.

• Journal of the Korean Wood Science and Technology
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• 제50권5호
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• pp.301-314
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• 2022

The moisture and dimensional behaviors of a nail-laminated timber (NLT)-concrete slab composed of an NLT-plywood composite and topping concrete are monitored for 385 days. The slab is developed for using as flexural elements such as floors. The humidity control of wood gently introduces significant fluctuations under the ambient relative humidity into the slab, and fluctuations in the relative humidity result in dimensional changes. The equilibrium moisture content of the slab increases from 6.7% to 15.3% during the monitoring period, resulting in a width (radial) strain of 0.58%. The length (longitudinal) strain is negligible, and the height (tangential) strain is excluded from the analysis because of abstruse signal patterns generated. Concrete pouring causes a permanent increase in the width of the NLT-plywood composite. However, the width deforms because the weight of the concrete mixture loosens the nail-laminated structure, not because of the significant amount of moisture in the mixture. The dimensional stabilization effect of the nail-laminated system is demonstrated as the composite strain is lower than the total strain of lumber and plywood, which are elements constituting the nail-laminated structure.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.743-746
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• 2004

This research investigates experimentally an effect on the properties of the high flowing concrete according to variations of concrete materials and site conditions. Variations of sensitivity test are selected items as followings; (1)Concrete temperature, (2)Unit water(Surface moisture of fine aggregate), (3)Fineness modulus of fine aggregate, (4)Addition ratio of high-range water reducing agent. And fresh conditions of the high flowing concrete should be satisfied with required range including slump flow$(65{\pm}5cm)$, 50cm reaching time of slump flow$(4\~10sec)$, V-box flowing time$(10\~20sec)$, U-box height(min.300mm) and air content$(4{\pm}1\%)$. As results of sensitivity test, material variations and site conditions should be satisfied with the range as followings; (1)Concrete temperature is $10\~20^{\circ}C$ (below $30^{\circ}C$), (2)Surface moisture of fine aggregate is within ${\pm}0.6\%$, (3)Fineness modulus of fine aggregate is $2.6{\pm}0.2$ and (4)addition ratio of high range water reducing agent is within $1\%$ considered flow-ability, self-compaction and segregation resistance of the high flowing concrete.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2002년도 춘계학술대회 논문집
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• pp.261-267
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• 2002

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 추계 학술논문 발표대회
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• pp.43-44
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• 2012

Deterioration factors such as CO₂ and chloride ions cause steel corrosion in RC structures. The diffusion of these factors depends on the water content in concrete. To examine the moisture condition of concrete, this research considers the availability of the steel effect ratio, which is calculated by Resistivity Estimation Model (REM). It is concluded that the steel effect ratio is expected to be available as a quantitative evaluation method in the assessment of concrete layer resistivity.

• Computers and Concrete
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• 제33권4호
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• pp.409-423
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• 2024

Using an extensive database, a sensitivity analysis across fifteen machine learning (ML) classifiers was conducted to evaluate the impact of various data manipulation techniques, evaluation metrics, and explainability tools. The results of this sensitivity analysis reveal that the examined models can achieve an accuracy ranging from 72-93% in predicting the fire-induced spalling of concrete and denote the light gradient boosting machine, extreme gradient boosting, and random forest algorithms as the best-performing models. Among such models, the six key factors influencing spalling were maximum exposure temperature, heating rate, compressive strength of concrete, moisture content, silica fume content, and the quantity of polypropylene fiber. Our analysis also documents some conflicting results observed with the deep learning model. As such, this study highlights the necessity of selecting suitable models and carefully evaluating the presence of possible outcome biases.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.745-748
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• 2008

On investigation about quick measurement technology of unit water at range of W/B=35% in high strength, the average error of the Di-electric constant moisture tester A has measured more than $23.0kg/m^3$ unit water content of design and the average error of the method of unit volume weigh was less than $-9.6kg/m^3$. The average error with mixing factor has influenced with a kind of sand, but had not influenced with unit water content of design. Therefore, it will be for introduce business decide require more than a study about cement, sand, superplasticizer, etc.

• 한국가금학회지
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• 제26권3호
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• pp.189-193
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• 1999

This experiment was conducted to investigate the effect of floor heating system on housing environment and performance in broiler production. PVC heating pipes(in 25cm spacing) were covered with concrete under the litter. Floor heating system was compared with conventional direct heating system. Each treatment had two replicates of 110 birds each. Litter moisture content was significantly reduced in floor heating system than conventional direct heating system(P〈0.05). Dust concentration was higher in floor heating system because of low litter moisture content. CO$_2$concentration was 2,900ppm and 1,500ppm on the direct heating system and floor heating system, respectively at the age of 1 week. Body weight was significantly higher in floor heating system at 7 weeks of age(P〈0.05). The results of the trial show that floor heating was useful heating system for broiler production.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.29-30
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• 2013

Steel corrosion is the most serious problem in RC structures. Even though patch repair method is normally applied in repair system, the effectiveness is not enough. Cathodic protection in active repair method to deteriorated RC structures. FEM model was developed to simulate the optimized cathodic protection condition. Iro oxidation, hydrogen evolution and oxygen reduction were considered to expect current distribution. Moisture content in concrete which can affect the electrolyte conductivity was used as initial condition.