• Structural Engineering and Mechanics
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• v.22 no.1
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• pp.71-83
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• 2006

This paper deals with the effects of various moisture environments on the structural behavior of concrete beams. The presented results were obtained within a large experimental program carried out at the Laboratoire Central des Ponts et Chauss$\acute{e}$es (LCPC), with Electricit$\acute{e}$ de France (EDF) as a partner. The aim of this paper is to point out and to quantify the strains resulting from unidirectional moisture conditions: a drying gradient applied during 14 months, followed by the re-wetting of the dried surface during 9 months. The effect of reinforcement on the shrinkage and on the deformation due to water absorption is pointed out. Moreover, a lot of tests on companion cylinders and prisms were carried out to determine the mechanical characteristics of the material and help checking analysis methods. The paper focuses on numerous measurements obtained during the 23 months on one plain concrete beam and one reinforced concrete beam: variation of water content, followed by precise weighing and gammadensitometry, relative humidity measurements, local and global deformations in the three directions and deflection of the beams. Thus, the effects of drying and water absorption on the behavior of concrete structures are documented and analyzed in comparison with existing representation of water diffusion.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1066-1072
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• 2000

This study is to investigate the pressure wave characteristics and the absorption of maximum and minimum pressure generated by instantaneous valve closure at the end of the straightening copper piping system with and without a water hammer arrester. Experiments were conducted under the following conditions : initial pressure 1~5 bar, flow velocity 0.6~3.0 m/s, water temperature $20^{\circ}C$ and air volume of water hammer arrester $80~180^cm^3$. Experimental results show that the optimum air volume of water hammer arrester is 110㎤.

• Clean Technology
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• v.7 no.4
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• pp.273-280
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• 2001

An absorber is a major component in the absorption refrigeration systems and its performance greatly affects the overall system performance. In this study, experimental analyses on heat transfer characteristics for removal of absorption heat in ammonia-water bubble mode absorber were performed. Heat transfer coefficients were estimated as the variations of input gas flow rate, solution flow rate, temperature, concentration, absorber diameter and height, and input flow direction. The increase of gas and solution flow rate affects positively in heat transfer. However, the increase of solution temperature and concentration affects negatively. Moreover, under the same Reynolds Numbers, countercurrent flow is superior to cocurrent flow in heat transfer performance. In addition, from these experimental data, empirical correlations which can explain easily the characteristics of heat transfer are derived.

• Journal of Adhesion and Interface
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• v.22 no.1
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• pp.22-28
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• 2021

Products using diatomaceous earth, which are used in various fields, are optimized for moisture absorption, but have problems such as high hardness, powder flying, and rough surface feel. To improve this, an olefin-based foam having low hardness and high elasticity was prepared by adding an excessive amount of inorganic material using EVA (Ethylene vinyl acetate) having low hardness and excellent elasticity. Diatomaceous earth was added to impart moisture absorption characteristics of the foam, and the moisture absorption/drying characteristics showed a moisture absorption rate of about 10 to 15% and a moisture drying rate of 10 to 70% depending on the content of the diatomaceous earth. Through this study, it was possible to manufacture a water-absorbing olefin-based foam with diatomaceous earth added, and it was confirmed that the diatomaceous earth added to the foam had a great influence on water absorption and dissipation due to its microstructure and characteristics.

• Korean Journal of Plant Resources
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• v.20 no.4
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• pp.267-271
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• 2007

This study was carried out to examine optimal hot water treatment time in Albizzia julibrissin seeds. Germination and moisture absorption characteristics among intact seeds, immersed seeds for 24 hours in distilled water and hot water treated seeds were surveyed. As result, treated seeds showed a highly significant difference with intact and immersed seeds (p<0.0l). Especially, treated seed for 2.0 minutes represented the highest percent of germination (PG). But mean germination time (MGT) did not have significant difference between non-treatment and treatments (p=0.502). Germination speed and germination performance index showed similar tendency with PG. In percent of moisture absorption (PMA) and moisture absorption rate constant (MARC) treatments had higher values than non-treatment whereas 2.0 minutes treatment was lower than non-treatment in initial moisture absorption rate (IMAR). In relation between germination properties and moisture absorption characteristics, all properties except MGT among germination properties had high correlations with PMA and MARC ($r=0.854{\sim}0.931$,p<0.01) whereas IMAR didn't have correlation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.68-75
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• 2021

This study performed simulating water absorption in various pre-cracked concretes. 2D-Finite Element Analysis (2D-FEA) model was developed based on experimental results on the amount of absorbed water in concrete with the exposure time. Results from the 2D-FEA showed that both crack width and crack depth strongly affect the amount of absorbed water in cracked concrete. In addition, water absorption rate is introduced and a predictive equation is suggested to estimate the rate in order to quantify the amount of absorbed water in cracked concrete. It was confirmed that water absorption in concrete having less than 150 mm crack depth was dominated as a main transport factor regardless of crack width. Therefore, considering that steel corrosion caused by chlorides dissolved in water mainly occurs in reinforced concrete structures, it is necessary that crack depth as well as crack width should be investigated in reinforced concrete structures at the time of field-inspection.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.2
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• pp.65-71
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• 1992

In most absorption machines, absorption enhancement has been achieved by adding small amount of surfactant additive, which introduced the surface tension difference between absorbent and surfactant droplets in the vapor absorption. The aim of this study is to understand a basic mechanism of Marangoni convection and its effectiveness in the vapor absorption enhancement. In this study, nonflowing aqueous solution of LiBr 60 mass% was exposed to saturated water vapor under the condition that two dropwises surfactant were fixed on the absorbent surface. Our experiments achieved to visualize the enhanced heat and mass transfer phenomena by the effect of Marangoni convection through the laser holographic interferometry. Also, Marangoni convection behavior was obtained by using tracer method.

• Journal of the Korean Geographical Society
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• v.50 no.5
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• pp.505-514
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• 2015

This study analyzes a correlation between water content values and chemical index of alteration (CIA) for coarse sedimentary rocks of Mt. Cheonsaeng in Gumi-si, Kyeongsangbuk-do. Through measurement of various water values of 20 samples including water content rate, water absorption rate and equipment measuring we comparatively analyzed the values with CIA of the samples obtained by X-ray fluorescence. As a result of analysis water content rate and water absorption rate in a sedimentary rock are likely to be higher when matrix is psephitic and less compact. Furthermore the higher water content rate is, the higher CIA is due to increase of $SiO_2$ and $Al_2O_3$ and decrease of CaO and $Na_2O$ derived by chemical weathering of felspar. This correlation between water content rate and CIA represents a similar result with previous studies targeting granite.

• Journal of the Korean Solar Energy Society
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• v.39 no.1
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• pp.21-32
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• 2019

Solar hot water system produces hot water using solar energy. If it is not used effectively, overheating occurs during the summer. Therefore, a lot of research is being done to solve this. This study develops thermoelectric power module applicable to solar hot water system. A thermoelectric material can directly convert thermal energy into electrical energy without additional power generation devices. If there is a temperature difference between high and low temperature, it generate power by Seebeck effect. The thermoelectric module generates electricity using temperature differences through the heat exchange of hot and cold water. The water used for cooling is heated and stored as hot water as it passes through the module. It can prevent overheating of Solar hot water system while producing power. The thermoelectric module consists of one absorption and two radiation part. There path is designed in the form of a water jacket. As a result, a temperature of the absorption part was $134.2^{\circ}C$ and the radiation part was $48.6^{\circ}C$. The temperature difference between the absorption and radiation was $85.6^{\circ}C$. Also, The Thermoelectric module produced about 122 W of irradiation at $708W/m^2$. At this time, power generation efficiency was 2.62% and hot water conversion efficiency was 62.46%.

• Food Science and Preservation
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• v.13 no.3
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• pp.344-350
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• 2006

Soaking and drying were studied for seven grains and legumes including glutinous rice, brown rice, glutinous brown rice, glutinous barley, Seoritae, Heuktae and red bean to improve taste of cooked mixed grams and make easy to cook then Seoritae and Heuktae showed the highest water absorption and the rest were in the order of glutinous barley, glutinous rice, milled rice, brown glutinous rice, brown rice, and red bean. In regards with water absorption index by soaking temperature, the higher the temperature showed, the more water absorption and the shorter time to reach the water absorption balance, the more grinding legumes. showed the more water absorption and the shorter time to reach to the water absorption balance. The soaked samples were dried at mom temperature $30^{\circ}\C,\;50^{\circ}\C$, and microwave 300 W, 700 W and 1000 W power. As a result 700 W drying method br microwave can dry samples in the shortest time without damage to the samples. Therefore, it was considered as the best pretreatment conditions for mixed stains to dry with 700 W microwave after one-hour soaking at $30^{\circ}C$.