• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.607-615
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• 2009

Analysis of chloride penetration into concrete is performed considering the repeated wetting and drying conditions of tidal zone, by means of the developed finite element program which enables the diffusion-convection analysis to be conducted. Heat conduction and moisture diffusion are also included in the finite element analysis program in order that their effects to chloride penetration may be considered. For the efficiency of calculation, the analyses of temperature, relative humidity and free chloride concentration are conducted successively in that order, by treating the convection of chloride due to moisture diffusion as an source or sink term. By comparing the analysis result from finite element analysis, where main variable is a wetting and drying period, with the chloride profiles from ACI Life-365 method, it is shown that the Life-365 method gives an accurate result for the submerged zone but does not consider the differences of wetting and drying period. To obtain an accurate chloride profile in the tidal zone, it is confirmed that the diffusion-convection finite element analysis should be applied.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.1
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• pp.11-15
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• 1988

Square slices of sea tangle was dried in constant condition of thickness (1.54mm), air temperature $(50^{\circ}C)$, relative humidity $(30\%)$ and air velocity (0.4m/s). The shrunk surface area and the shrinking rate were investigated. The results obtained are summarized as follows : 1) Comparing the shrinking of transverse section with that of vertical section, the transverse section was proceeded more double shrinkage than vertical section. 2) The shrunk surface area curve showed nearly a linear shrinkage up to 90min of drying time. 3) The shrinking rate was rapidly increased in first falling rate period, and was largest in the early period of second falling rate period.

• Tribology and Lubricants
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• v.34 no.6
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• pp.235-240
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• 2018

Superlubricity refers to the lubrication phenomenon that occurs when the friction coefficient is lower than 0.01. In recent years, this phenomenon has received a significant amount of attention because it can greatly contribute to the reduction of economic and environmental losses caused by friction and wear. In the case of acid lubricants, only ceramic materials can be used for superlubricity, and it takes a long running-in period to enter the superlubricity regime. In this work, we investigated the superlubricity effect of vitreous enamel coating on SUS304. We also examined the running-in period of vitreous enamel coating under phosphoric acid lubricant condition with respect to surface treatments. Drying and polishing methods were used to treat the vitreous enamel coating on the specimen. The friction experimental results revealed that superlubricity could be achieved with vitreous enamel coating. It was also found that the drying and polishing methods can significantly reduce the running-in period and improve the wear properties of vitreous enamel coating. In particular, the polishing method shortened the running-in period by approximately 99% and reduced the wear rate by approximately 99%, compared to nontreated vitreous enamel coating.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.4
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• pp.315-326
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• 1996

An experiment was carried out to determine effect of cultivar, drying agent concentration and preservative on the moisture content, temperature and quality changes of fall harvested oat(Avena sativa L.) hay during field curing and storage. The main plots consisted of the cultivar such as 'Foothill' and 'Swan', the subplots consisted of drying agent concentration such as 7Skg/ha(C1), lOSkglha(C2) and control(C0) and the sub-subplots consisted of preservative such as buffered acid(BA), lactic bacteria inoculant(LB) and control(C0). Moisture contents of 'Foothill' and 'Swan' oat cultivar at harvest were 635.5 and 385.4%DW(Dry weight), respectively, but the final moisture contents of the oat cultivars were 117 and 86%DW. The moisture content of cut oat was not affeded by drying agent concentration. Core temperature of baled 'Swan' oat hay was a little higher than that of 'Foothill' and no consistent preservative effect was found. Total nitrogen content of 'Swan' oat hay was 3.08% and that of 'Foothill' oat hay was 3.45%(P<0.05). Drying agent treatment increased total nitrogen content of 'Swan'(P <0.05), but preservative had no effect. Crude fiber content of oat cultivar was increased as the curing progressed(P<0.05) and the difference of crude fiber content of oat cultivar was maintained through the whole curing period. Effect of drying agent concentration on crude fiber content was not found after preservation. Crude fiber content of 'Swan' oat hay was higher than that of 'Foothill' by 1.O% in ADF and 3.1 % in NDF(P<0.05). No preservative effect was found in crude fiber content. According to RFV of oat cultivar at harvest, forage quality of 'Foothill' and 'Swan' was Prime and Grade 1, respectively, but that of both cultivm was above Grade 2 at the final curing day. RFV of the stored 'Foothill' and 'Swan' oat hay was 122 and 114(P<0.05), respectively, and the quality of oat hay was classified as Grade 1 and 2, respectively, according to the forage quality standard assigned by AFGC.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.31-37
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• 2017

The use of half PC slab has been increasing to shorten construction period. Because the drying shrinkage of topping concrete is restrained by PC slab, the tensile stress is generated at the topping concrete and the cracks can be occurred at the topping concrete due to drying shrinkage. Therefore, it is important to predict the tensile strain of half PC slab due to drying shrinkage to improve the quality of half PC slab. However, there is no studies on prediction of shrinkage behavior of half PC slab yet. Therefore, in this study, half PC slab was made, and the predictability of tensile strain generated at half PC slab due to drying shrinkage was investigated. The step by step method considering creep was used to estimate the tensile strain of half PC slab. In result, good agreement was obtained between the analytical and experimental values.

• Conservation Science in Museum
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• v.14
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• pp.7-12
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• 2013

The conservation has been conducted for the fragments of an wooden boat in the Neolithic Age, excavated from Bibong-ri, Changnyeong, Korea. The vacuum-freeze drying have been applied to mostly to the small relics, such as wooden lacquerwares or small wooden goods etc.. Therefore, the large objects like a wooden boats have been treated almost by air-drying after impregnation with aqueous PEG solution. The air-drying is needed to impregnate with PEG aqueous solution during long period and run the risk of the fault generation. This report explain an example adapted for the fragments of the wooden boat by humidity-controlled drying(HCD) with slow adjusting moisture content. We did the chemical pre-treatment, PEG aqueous solution. The concentration of the aqueous solution was increased gradually from 10% to 80%. After the impregnation, the objects were dried by the HCD. The dimensional stability of the fragments after treatment was good.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.221-228
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• 2001

This study was carried out to investigate the effect of germination condition and drying temperature on growth and physicochemical properties of brown rice. Three brown rice seeds of Ilpumbyeo, Dasanbyeo and Heugjinjubyeo were stored at room temperature for six weeks to test the time-sequence germination viability. Relatively stable germination ratio was maintained until 2 weeks after storage. However, 3 weeks after storage, germination ratio of brown rice seeds started to decrease rapidly and their germination ratio was lower than 80%. For this reason, brown rice was recommended for seeding within 2 weeks after hulling. During the initial 5 days, germination ratio of 24 hours pre-soaking brown rice was higher about 2-3% than that of non-soaking brown rice. The $25^{\circ}C$ was considered as the most favorable temperature for brown rice germination, because of the high germination ratio and desirable coleoptile growth of the brown rice, and little seed rotting symptoms. The scanning electron micrographs showed the structural differences between hot-air dried and freeze dried germinated-brown rice kernel. In the freeze dried germinated-brown rice, seed coat (pericarp, tegmen and aleurone layer) was mechanically disrupted from the endosperm, and many cleavages were observed among starch storing cells and starch granules. The endosperm of freeze-dried brown rice kernels formed the sponge-like structures and showed the fragile traits. For this reason, hot-air drying is considered as more suitable method than freeze drying for germinated-brown rice. The crude protein and amylose contents were slightly changed, but there were no significant differences during the germination period. Crude fiber content was decreased, but crude Int and total amino acid contents were increased as seeding days increased. A rapid increase in $\alpha$-amylase activities of germinating brown rice was observed at S days after seeding, and $\alpha$-amylase activities were decreased from 8 days after seeding. Total free sugar contents were decreased during the germination period. There was continuous decline in the contents of sucrose and glucose until 8 days after seeding, but fructose and maltose content were gradually increased from the 5 days after seeding.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4032-4038
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• 2014

Vegetable fatty acid solid soap requires a drying process for moisture evaporation and hardness after being manufactured through saponification. Although the soap is manufactured by mixing additives mainly from natural ingredients, existing studies have focused primarily on the usability of vegetable solid soap. Consequently, research into the physical properties of vegetable fatty acid solid soap mixed with natural ingredients has been unsatisfactory. Therefore, this study attempted to compare and observe the changes in the physical properties (pH, surface tension, critical micelle concentration, and cleansing power) of solid soap in accordance with the drying period and additives (tea tree E.O and $TiO_2$) using pH paper, the Du Nouy measurement method, sedimentation method, and ultrasound washer. Regardless of the mixture with additives, vegetable fatty acid solid soap showed the same pH, and there was no change in the pH while maintaining pH 8 beginning from the $2^{nd}$ weeks to $12^{th}$ weeks of drying. In addition, as a result of measuring the surface tension and CMC, regardless of the drying period, only the soap added with $TiO_2$ showed an even value of 62.5mg/L, whereas the other soap specimens showed a decline in CMC to 25mg/L on the fourth week of drying. As a result of measuring the detergency, the removal efficiency of vegetable fatty acid solid soap mixed with tea tree E.O and $TiO_2$ and dried for four weeks was 4.50~4.65%, which was higher than that of the vegetable fatty acid solid soap without additives (3.62~3.92%).

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.65-73
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• 2018

This study was carried out for 20 days in a bio-drying batch reactor under the blowing conditions of 0.75, 1.00, 1.25, and $1.50L/min{\cdot}kg$ in order to optimize the operating conditions for the bio-drying of food wastes. The decomposition rate of organic matter during the bio-drying operation period was analyzed using modified Gompertz model. The maximum organic degradation (P) was 2.31, 2.52, 2.27 and 1.88 kg at air flow rates of 0.75, 1.00, 1.25 and $1.50L/min{\cdot}kg$, and the maximum organic degradation rate was 0.33, 0.45, 0.28, and 0.18 kg/day at 1.00, 1.25 and $1.50L/min{\cdot}kg$, respectively, showing excellent organic decomposition efficiency at a air flow rate of $1.00L/min{\cdot}kg$. The lag growth phase time (${\lambda}$) of the bio-drying reactor was 2.10, 1.48, 1.15, and 1.06 days at 0.75, 1.00, 1.25 and $1.50L/min{\cdot}kg$, respectively. The water removal rate in the operation of bio-drying reactor of food waste increased with the increase of air flow rate from the early stage of bio-drying to the middle stage, and the highest water removal rate was observed at the air flow rate of $1.00L/min{\cdot}kg$ at the end of bio-drying. The optimum air flow rate condition of bio-drying reactor was $1.00L/min{\cdot}kg$.

• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.39-45
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• 1995

The plywoods commonly used as decorative interior materials for the construction are inflammable and so it is a causative factor for making fire accidents, resulting in the destruction of human life and personal properties. Indeed, it is, therefore, required to produce fire-retardant plywoods. In this study, a special grade of defect-free, Kapur plywood was used. Specimens were cut into 3- by 20cm dimensions from 120- by 240- by 0.33-cm panels(thin panel) or 120- by 240- by 0.5-cm panels(thick panel). Some specimens were treated with diammonium phosphate(DAP), but some were not treated with diammonium phosphate to use as control panels. Chemical absorption, drying curves, drying rates and dynamic Young's modulus were investigated. The results were summaries as follows; 1. The specimens were soaked into 19% diammonium phosphate solution by a full cell pressure process and the diammonium phosphate retained in the thin and thick plywoods was 1.409kg/$(30cm)^3$, 1.487kg/$(30cm)^3$, respectively. 2. Diammonium phosphate-treated plywoods were redried with press-drying process at one of either condition dried on the platen($115^{\circ}C$) for a period of time or dried on the platen($50^{\circ}C$) for 3 hrs plus in a dry-oven($30^{\circ}C$) for 24 hrs. or dried on the platen($60^{\circ}C$) for 2 hrs plus in a dry-oven($30^{\circ}C$) for 24 hrs. The drying rate of treated thin specimens dried at $60^{\circ}C$ plus $30^{\circ}C$ and $115^{\circ}C$ only was found to be 0.04 %/min. and 8.53 %/min. Similarly, the drying rate of treated thick specimens were 0.03 %/min. and 6.77 %/min. respectively. 3. It was evident that highly-significantly different drying rate of treated plywoods was observed between plywood thicknesses and platen temperatures and the rate was increased by elevating the platen temperature up to $115^{\circ}C$. Based on the two-way variance analysis, highly significant drying rate was observed from the interaction between plywood thicknesses and platen temperatures. 4. After redrying, the specimens were weighed and reconditioned to a constant weight in a facility maintained temperature ($20^{\circ}C$) and relative humidity(65%) prior to test dynamic Young's modulus. The test revealed that the thin specimens dried at the platen temperature of $50^{\circ}C$, $60^{\circ}C$, $115^{\circ}C$ and untreated specimens showed 1.070E+09 dyne/$cm^2$, 1.156E+09 dyne/$cm^2$, 1.243E+09 dyne/$cm^2$, and 1.052E+09 dyne/$cm^2$, respectively. Likewise, the thick specimens revealed 5.647E+09 dyne/$cm^2$ 5.670E+09 dyne/$cm^2$, 6.395E+09 dyne/$cm^2$ and 5.415E+09 dyne/$cm^2$, respectively. 5. It was evident that significantly different dynamic Young's modulus was observed between the plywood thickness and the platen temperature, but not in the two-way interaction between the plywood thickness${\times}$the platen temperature.