• Journal of the Korea Institute of Building Construction
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• v.6 no.1 s.19
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• pp.73-77
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• 2006

Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidify. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. As a result Strain Rate of Drying Shrinkage of concrete was measured to increase by average $10{\times}10^{-5}$ in proportion to additional 4% increase in fine aggregate ratio, when water/cement ratio constant. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. 6. Strain Rate of Drying Shrinkage in sea sand concrete increased $10%{\sim}15%$ higher than measured when in river sand. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as fellows. The coefficient of correlation of Drying Shrinkage in concrete was over 90%.

• Journal of the Korea Institute of Building Construction
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• v.4 no.4
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• pp.71-77
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• 2004

Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidity. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. Strain Rate of Drying Shrinkage of concrete under the condition of dry air appears to rise by about 20%-30% in proportion as the temperature rises $5^{\circ}C$ when the humidity was held below 10% compared under the condition of dry temperature & Humidity test chamber. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. A general formula with two variables is derived as follow ${\varepsilon}={\alpha}_1＋{\beta}_1x_1＋{\beta}_2x_2＋{\beta}_3x_1^2＋{\beta}_5x_2^2$. and also graphed in 3 dimensions, enabling to apply to actual design and predict Strain Rate of Drying Shrinkage in concrete. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as follows. The coefficient of correlation of Drying Shrinkage in Concrete was over 90%.

• Magazine of the Korea Concrete Institute
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• v.4 no.1
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• pp.127-134
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• 1992

Generally speaking, the internal moisture of concrete is mainly distributed in inner part and concrete surface which is exposed are dned according to influence of temperature and humidity. So, the properties which are compressive strength, modular elasticity, and volume change are different at each part even in same concrete. This is because moisture distribution is changed according to the evaporation and move ment of moisture, exist in the inner porosity of concrete. Therefore, it is necessary that we investigate the properties of concrete according to moisture distribution. The purpose of this study is investigating correlation between the moisture content and mechanical properties in concrete. Compressive and tenslle strength decrease according to increasing moisture content, but modular elas ticity increase. Those increasing or decreasing ratio at drying ratio 100% (absolute dries) is as follows in comparative of drying ratio 0 % (saturated condition).tion).

• The Korean Journal of Food And Nutrition
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• v.35 no.6
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• pp.426-434
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• 2022

In this study, the effect of osmotic drying conditions of mangoes on hot air drying was investigated. Four different osmotic agents of 60 Brix, such as S60, SM10, HF80, and SG25, were prepared. Mango slabs were osmotically dried with the agents at a ratio of 1:4 (w/w) for up to 8 hours. SG25 showed the lowest weight reduction and moisture loss during the process. As a result of hot-air drying, all samples showed a high correlation with the Page model (0.9761~0.9997), and the required drying time of all samples that were osmotically dried was reduced compared to the non-osmotically dried group. After hot-air drying, the pH value increased according to the drying temperature. The L, a, and b values and the total polyphenol content also decreased. Through this study, the possibility of osmotic drying was confirmed to increase the efficiency of hot air drying of mangoes, which is expected to contribute to the industrial use of domestic mangoes.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.136-143
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• 2016

There are various method for evaluating the durability life of concrete structures due to salt damage. The best way is to perform a corrosion test for a rebar embedded in concrete specimen was exposure to marine environment. However, this method has the disadvantage that it takes a long period of time. Also, accelerated corrosion test which was complemented complements the time-consuming weakness is limited to apply because it could not reveal a correlation between long-term exposure test. Accordingly, the purpose of this study is to derive a correlation coefficient between cycle drying-wetting accelerated corrosion test and long-term exposure test. Corrosion initiation time was measured in four types of concrete samples, i.e., two samples mixed with fly ash(FA) and blast furnace slag(BS), and the other two samples having two water/cement ratio(W/C = 0.6, 0.35) without admixture(OPC 60 and OPC 35). The accelerated corrosion test was carried out by two case, i.e., one is a cyclic drying-wetting method(case 1), and the other is a artificial seawater ponding test method(case 2). Whether corrosion occurs, it was measures using half-cell potential method. The results indicated that case 1 is to accelerated the corrosion of rebar about 24~36% as compared with case 2, then the corrosion of rebar embedded in concrete occurred according to the order of OPC60, FA, BS, OPC35. Correlation coefficient between accelerated corrosion test and long-term exposure test, case 1 is 4.23 to 5.42, and case 2 is 6.54 to 7.82.

• Culinary science and hospitality research
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• v.23 no.7
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• pp.220-233
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• 2017

The purposes of this study were: (1) to examine the quality characteristics of the Sulgidducks added with barley sprouts by blanching (CON), freeze-drying (FBP), hot-air drying(HBP); (2) to examine the quality characteristics of Sulgidduck such as the moisture content, the color value, the textural properties and the sensory evaluation; (3) to find the optimal ratio of barley sprouts, which were made by the three different drying methods. As a result, the Sulgidduks containing barley sprouts by CON showed a lot of significance and high correlation depending on the amounts of the barley sprout(p<0.05). As the amounts of CON, FBP and HBP increased, the L and the a values of Sulgidducks significantly decreased, whereas the b values of them increased. For the textual properties of the Sulgidducks, on the first day, the concentration in CON up to 6% showed no significant differences in the hardness, cohesiveness, springiness, and chewiness. In case of FBP, the increase in the additives caused decrease in the hardness, adhesiveness, springiness, and chewiness of the Sulgidducks on storage 0 day(p<0.05). As the amounts of HBP increased, the hardness, springiness of the Sulgidducks on the first day decreased(p<0.05). Conclusionally, 6% blanched barley sprout added group, 2% FBP and HBP were highly rated in color, flavor, bitterness, chewiness, overall acceptability and all sensory quality characteristics.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.3
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• pp.29-36
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• 2001

This paper was made to evaluate the effect of the blending ration of GCC and No. 1 clay on the printability by investigating the structure of pore such as the pore rate, the number of pores, pore size and distribution of coated paper. The coated structure is mainly depended on the results of correlation between pigment and binder. It means that the structure of the pore occurred is chiefly affected by the blending ratio of GCC and No. 1 clay. This physical properties of the pore have a close relation with ink set-off associated with the drying rate and the penetration in ink into base paper and with printing gloss. Therefore it was needed to find out how the pore structure and the printability will be changed by modifying the blending ratio of GCC and No. 1 clay to vary the pore structure of coated paper. Below are the results of measurement: As the blending ratio of clay going up, water retention, sedimentation volume. smoothness, and paper gloss were increased, but relatively brightness and opacity were decreased. Pore rate was the highest at the blending ratio of No. 1 clay to GCC, 70:30. In this case, average pore radius was also increased. Ink receptivity and K&N ink receptivity were improved with the increase of the blending ratio of GCC, where was, ink setting was vice versa. No difference was observed in the weight of ink, but ink repellance decrease with the decrease of blending ratio of GCC.

• Korean Journal of Materials Research
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• v.23 no.12
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• pp.687-694
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• 2013

This study was performed with an aim to improve the early-age strength of concrete containing fly ash, which is known to increase the long-age strength of concrete, reduce drying shrinkage, and enhance water tightness. The composition was partially substituted with calcium sulfoaluminate (CSA), from which ettringite is actively produced, in the early stages of hydration to verify its effect on improving the early-age strength and to determine the optimal mixing ratio. For this purpose, up to 30 % of the cement weight was substituted with fly ash, and the amount of CSA substitution was 8% of the fly ash weight. The mixtures were then fabricated into concrete specimens for compressive strength measurement and analysis of the correlation between the hydration products and the compressive strength.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.113-118
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• 2017

BACKGROUND: The carbon (C) isotope ratio (${\delta}^{13}C$) of dissolved organic C (DOC) is an indicator of water pollution source. In this study, the potential use of two pre-treatments for the ${\delta}^{13}C$ analysis, alkaline persulfate oxidation coupled with carbonate precipitation (precipitation) and freeze drying (drying), were compared to suggest a more feasible pre-treatment method. METHODS AND RESULTS: Two reference materials with different ${\delta}^{13}C$ values were used for the experiments; chemical grade glucose ($-12.0{\pm}0.02$‰) and pig manure compost extract ($-23.3{\pm}0.04$‰). In the precipitation method, the measured ${\delta}^{13}C$ values were consistently lower than the theoretically calculated values as dissolved $CO_2$ could not be removed due to the alkaline property of the reagents and the dissolution of air $CO_2$ into the alkaline solution. The drying method also resulted in more negative ${\delta}^{13}C$ than the calculated ${\delta}^{13}C$; however, the difference was systematic ($3.9{\pm}0.3$‰) and there was a strong correlation (${\delta}^{13}C_{calculated}=0.87{\times}{\delta}^{13}C_{measured}-0.624$, $r^2=0.98$) between the calculated and measured ${\delta}^{13}C$. Calibration of ${\delta}^{13}C$ using the relationship between the calculated and the measured ${\delta}^{13}C$ values produced reliable and accurate ${\delta}^{13}C$ values. CONCLUSION: Our results suggest that the drying method is more accurate pre-treatment method to minimize the influence of air $CO_2$ compared to the precipitation method for the determination of ${\delta}^{13}C$ of DOC.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.4
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• pp.589-598
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• 2000

A pilot-scale Spray Drying Sorber (SDS) system was set up to evaluate the effect of spray characteristics on the desulfurization yield. The size distribution and the Sauter Mean Diameters of slurry droplets were measured in advance using the optical size measurement system, Malvern 2600. The desulfurization yield of the drying chamber by size was measured for the conditions of inlet gas and spray injection. As a reagent, 10% limestone slurry of $Ca(OH)_2$ was treated with flue gas containing $SO_2$, and the combustion gas analyzer and gas detectors were attached to measure the $SO_2$ concentration. With a flow rate of 144 Nm3/h and a temperature range of $200{\sim}300^{\circ}C$, the experiments were performed for the Stoichiometric Ratio (SR) of 1.0 to 3.0 and droplet mean diameter of 6.5 to $34.3{\mu}m$. In case of smaller spray droplets, the desulfurization efficiency improved due to the increase of total droplet surface area, while the reduction in evaporation time reduced the contact time between the droplets and $SO_2$ gas. In some typical region of droplet diameter, this negative effect, reduction of contact time, became dominant and the desulfurization yield decreases the desulfurization yield in spite of the expansion in absorption area. These results revealed that there exists the optimal size of spray droplets for a given state, which is determined by the compromise between the total surface area of slurry droplets and the evaporation time of droplets. The measurements also indicated that the inlet temperature of flue gas changes the optimal injection condition by varying the driving force for evaporation. The results confirm that the effect of the evaporation time of slurry droplets should be considered in analyzing the desulfurization yield as well as the total surface area, for it is a significant aspect of the correlation with the capabilities of $SO_2$ absorption in wet droplets. In conclusion, the optimal condition of spray can be determined based on these results, which might be applied to design or scale-up of SDS system.