• 콘크리트학회지
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• 제4권1호
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• pp.127-134
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• 1992

일반적으로 콘크리트 내부의 수분은 주로 중심부에 분포되어 있으며, 노출된 콘크리트의 표면은 주위의 온습도영향에 따라 건조하게 된다. 이에 따라 동일 부재내에서도 부위에 따라 함수율이 달라지게 된다. 이는 콘크리트의 내부공극에 존재하고 있는 수분의 증발과 이동으로 인하여 함수상태가 달라지기 때문이다. 이와 같이 콘크리트의 함수상태변화로 인하여 압축강도, 탄성계수, 용적변화등의 제성상이 각 부위에 따라 달라질 것으로 예상된다. 따라서, 콘크리트의 함수상태에 따른 콘크리트의 제성상을 명확히 파악함은 매우 중요하다고 판단된다. 본 연구에서는 콘크리트의 함수상태와 역학적 성상을 규명하는데 그 목적이 있다. 콘크리트의 함수량이 증가할수록 압축강도와 인장강도는 감소하나, 탄성계수는 증가한다. 본 연구에서 실험을 통하여 이와 같은 콘크리트의 성상과 함수상태와의 상관관계를 밝혔다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
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• pp.428-433
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• 2008

The strength capacity properties of concrete are much influenced by water content which has a significant effect on concrete spalling, especially, in high temperature areas. Therefore, the properties of the material's shall be closely examined first by measuring the water content in each material in order to analyze Concrete Fire Characteristics, and a reliable measuring method shall be presented in order to derive the following influence. The method used to measure the water content within concrete is mainly divided into 4 types; ASTM method, Nuclear Magnetic method, Ultrasonic measurement method, Radio Wave method, etc. It is essential to use a reliable measuring method for each experiment. In this experiment, we measured the water content and humidity of concrete by two methods; Relative/Absolute humidity method using VISALA HM44 measuring equipment which is easily measurable compared with other methods regardless of the shape of the experimental model, and a water content measuring experiment using ASTM C 566. If the aggregates are under the condition that their surface is dry but in saturation, there is no change of water content according to concrete curing methods. However if the aggregates are absolutely dry, the water content is significantly changed according to concrete curing methods.

• Journal of Biosystems Engineering
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• 제22권3호
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• pp.279-288
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• 1997

This study was worked out to obtain fundamental data needed for developing a continuous type dryer. The drying process in a cross-flow type continuous dryer was expressed as partial differential equations, and a drying simulation model for predicting rice moisture content, rice temperature, drying air absolute humidity, drying air temperature was developed by using the finite difference method. To validate the performance of the drying simulation model, a prototype continuous dryer was constructed in this study. The size of the test dryer was one-tenth to that of a commercial continuous dryer. The difference in the outlet rice moisture content between the predicted values and the measured values was within 0.5%, that of outlet rice temperature was below $3^{\circ}C$, that of drying air temperature in drying bed was within $8^{\circ}C$ and that of relative humidity of outlet drying air was big because of the different measuring point. In addition, a drying simulation model for a actual size continuous dryer with double flow was developed in this study. This drying simulation model included the rice mixing effect in the middle of drying length. The difference of outlet moisture content between the predicted and the measured values showed below 0.5% in this study.

• 한국공간구조학회논문집
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• 제21권2호
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• pp.99-110
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• 2021

This study presents the estimation of crack depth by analyzing temperatures extracted from thermal images and environmental parameters such as air temperature, air humidity, illumination. The statistics of all acquired features and the correlation coefficient among thermal images and environmental parameters are presented. The concrete crack depths were predicted by four different machine learning models: Multi-Layer Perceptron (MLP), Random Forest (RF), Gradient Boosting (GB), and AdaBoost (AB). The machine learning algorithms are validated by the coefficient of determination, accuracy, and Mean Absolute Percentage Error (MAPE). The AB model had a great performance among the four models due to the non-linearity of features and weak learner aggregation with weights on misclassified data. The maximum depth 11 of the base estimator in the AB model is efficient with high performance with 97.6% of accuracy and 0.07% of MAPE. Feature importances, permutation importance, and partial dependence are analyzed in the AB model. The results show that the marginal effect of air humidity, crack depth, and crack temperature in order is higher than that of the others.

• 한국건축시공학회지
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• 제23권1호
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• pp.1-9
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• 2023

본 연구에서는 보편적으로 건물의 옥상 등에 사용되는 폴리 우레탄 방수재의 바탕구조물의 함수정도와 시공환경조건에 따른 하자원인을 분석하기 위한 것으로 바탕판의 함수조건에 따른 부착강도, 표면상태를 육안관찰하였고, 온도, 습도의 양생조건에 따라서 방수재 도막의 기계적 성능을 평가하였다. 실험결과 바탕판의 함수상태가 10%이상일 때 도막의 부착이 이뤄지지 않음을 확인하였고, 온습도 조건이 20℃, 80% RH일때는 기초물성이 모두 확보되었으나, 40℃, 60% RH일 때 표면에 기포가 관찰되었으며, 40℃, 80% RH일 때 건조도막 기초물성이 KS F 3211 성능기준이하로, 우레탄 방수재 도포에 있어 시공환경조건의 하자원인 중 바탕판의 함수조건 및 양생 시 절대습도가 중요한 요인임을 확인하였다.

• 한국버섯학회지
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• 제14권2호
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• pp.39-43
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• 2016

생육실 내 외부 환경조건과 종균 배양 및 자실체 특성검정 결과 다음과 같은 결론을 얻을 수 있었다. 먼저, 종균배양이 외부 온도의 영향을 받는 것을 확인할 수 있었다. 배양실의 환경 조건($22^{\circ}C$, 65-68%, 700-1,200 ppm)을 일정하게 하여도 외부 기온이 낮고, 건조해지는 1월(동절기)에는 16-18일 가량 늦은 것을 확인하였다. 또한, 외부 기후에 따라 생육실 내부 환경이 영향을 받아, 자실체 생장이 느리고 발생 형태가 다른 것을 확인하였다. 동일한 조건($18{\pm}1^{\circ}C$, 85-95%, 700-1,200ppm)을 설정한 생육실에서 재배한 버섯이 수량(무게), 길이(크기) 모두 1월에 수확한 버섯이 3월에 수확한 버섯에 비해 작은 수치임을 확인하였고, 경도가 작아 품질 면에서도 양호하지 못함을 확인하였다. 이는 1월 외부의 영하의 저온과 60% 이하의 저습에 의해 생육실 내부 환경이 변화하여 일어난 현상임을 알 수 있었다. 아울러 버섯의 특성은 일정 시일이 지난 후 외부 기후를 보완하여 실내 환경을 조절하여도 개선되지 않음을 확인하였다. 일정 기간이 지난 후의 조치는 균의 노후화만 진행시켜 색만 변화할 뿐 크기가 커지거나 침이 형성되지 않았다. 그러므로 환경스트레스를 받지 않도록 미리 예방하는 것이 필요하다. 환기와 생육관리를 위해 생육실 내부 환경이 외부로 노출될 때, 외부 환경이 영향을 미치지 않도록 에어커튼 혹은 보온 커튼을 덧대어 문제가 발생하지 않도록 해야할 것이다. 특히, 동절기와 같이 외부 기온이 낮고, 습도가 낮은 시기에는 특별히 주의가 필요할 것이다.

• Journal of Mechanical Science and Technology
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• 제15권4호
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• pp.492-499
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• 2001

The characteristics of Prand시-Meyer expansion of supersonic flow with condensation along a wavy wall in a channel are investigated by means of experiments and numerical analyses. Experiments are carried out for the case of moist air flow in an intermittent indraft supersonic wind tunnel. The flow fields are visualized by a Schlieren system and the distributions of static pressure along the upper wavy wall are measured by a scanning valve system with pressure transducers. In numerical analyses, the distributions of streamlines, Mach lines, iso-pressure lines, and iso-mass fractions of liquid are obtained by the two-dimensional direct marching method of characteristics. The effects of stagnation temperature, absolute humidity, and attack angle of the upper wavy wall on the generation and the locations of generation and reflection of an oblique shock wave are clarified. Futhermore, it is confirmed that the wavy wall plays an important role in the generation of an oblique shock wave and that the effect of condensation on the flow fields is apparent.

• 대한기계학회논문집B
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• 제30권12호
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• pp.1188-1195
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• 2006

This paper examines the critical air temperature at which frost formation does not occur on a cold plate in order to improve the efficiency of a heat pump. The critical air temperature on test points is obtained from numerical analysis and a correlation of the critical air temperature is derived as a function of frosting factors (air absolute humidity, air velocity, and cold plate temperature) by least square method. Experiments are carried out to verify the correlation proposed in this study, and the prediction obtained with the correlation agrees well with the experimental data. Based on the correlation, we propose the non-frosting regions according to frosting factors.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.224-229
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• 2009

Performance curve of the desiccant rotor is an important information when developing and selecting the desiccant dehumidifier. The effective utilization of the energy is major capacity for the system and the desiccant performance curve is a design ability for a designer. By the rotor supply contract with DRI, ECO-DRY programs would be offered. Moreover, it could make remarkable progress in the desiccant system and energy saving. It is good to introduce the programs with the amicable help of DRI.

• 전기학회논문지P
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• 제61권1호
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• pp.55-58
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• 2012

By using EEG and HRV, subjects were estimated on their psychological and physiological reaction when reading psychrometric chart in 7 point century font, in an environmental test room in the condition of temperature 25[$^{\circ}C$], relative humidity 50[RH%], air current speed 0.02[m/sec], giving variation in illuminance to 0.1, 300, 600, 1000, 1300 and 1600[lux]. As a result, it was at 1300[lux] that absolute ${\alpha}$ wave, SMR, SDNN were most vitalized, and also both sides ${\alpha}$ wave asymmetry index, SEF50, HRT, stress and fatigue degree were at the lowest. It was found that a certain illuminance which minimizes psychological stress and fatigue degree while enhancing concentration and task achievement stably does exist.