• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.92-97
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• 2001

This paper was studied on the effect of temperature on corrosion of absorption refrigeration systems using LiBr-$H_2O$ working fluids. In the fresh water and 62 %lithium bromide solution at $70^{\circ}C$, polarization test of SS 400, Cu(Cl220T-OL) and Ni-Al bronze was carried out. And Polarization behavior, polarization resistance characteristics, corrosion rate(mmpy) and corrosion sensitivity of materials forming absorption refrigeration systems was considered. The main results are as following: As the experimental temperature increase, the change of corrosion rate of Ni-Al bronze become duller than SS 400 and Cu in 62 % lithium bromide solution. Open circuit potential of SS 400 is less noble than that of Cu and Ni-Al bronze in fresh water, but that becomes noble than Cu and Ni-Al bronze in 62 % lithium bromide solution. The corrosion sensitivity of Ni-Al bronze was controlled than that of Cu and SS 400 in 62% LiBr solution.

• Journal of the Korean Wood Science and Technology
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• v.19 no.4
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• pp.52-61
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• 1991

In this paper, the difference of the property of absorption and desorption for five species in semi-steady state are studied. The species used are listed in Table 1 and the dimension of specimen was $8\times8{\times}T$(Tangential direction)cm and tested in various conditions. A change of average moisture content with time were measured in each cycles. The results obtained are summarized as follows. When the relative humidity in air was maximum or minimum, the distribution of moisture In wood of all specimens were illustrated by exponential curves of decrease or increased from lace 10 center of wood. From the consideration of coefficient of decrease(C), the amount of moisture change of spruce was larger than the others. The pheonomenon was considered no relation to the specific gravity in air dry, but the wood structures. The velocity of the absorption and desorption for species decreased in the order spruce(Picea sitchensis) neodobam(Fagus crenata), solsong(Tsuga heterophylla), meranti(Shorea sp.) and kaesoo(Cercidiphyllum japoicum). In case of constant temperature and water vapor pressure is changed. the amount of absorbed moisture was larger than that of constant water vapor pressure and temperature vaned. In this fact, it is considered that the property of sorption of wood is strongly influenced by vapor pressure gradient than temperature gradient.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.892-901
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• 2018

Because of excellent electrical properties, epoxy resin is widely used in packaging and casting power equipment. Moisture and temperature in the environment are inclined to seriously affect the insulation tolerance of epoxy resin. This work focuses on the aging characteristics of epoxy resin in hygrothermal environment. Scanning electron microscopy images show that there are micro-crack, micro-slit and holes inside aged samples. The moisture absorption process undergoes three equilibrium stages and it does not follow the Fick's second law. Observing the change of hydrogen bonds in the infrared spectra of the dried samples, it is found that chemically moisture absorption immerges when the physical moisture absorption entered the third equilibrium stage. By Debye equation to fit the imaginary part of the dielectric constant, it is concluded that the uniformity of water molecule has a great influence on the electrical conductivity loss. Furthermore, the polarization loss can be more easily affected by water molecules than small free molecules. After the aged samples being dried, their real and imaginary part of the dielectric constant descend, but their original electrical properties cannot completely restored. After chemical moisture absorption appears inside the material, the residual space charges increase significantly and the charge dissipation rate slow down obviously.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.46-51
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• 2006

In order to utilize the refrigerants condensation heat of condenser on the absorption chiller system, the solution cooling condenser(SCC) were proposed, which weak solution of absorber outlet use as a cooling water. As the UA of the solution cooling condenser increased, increasement of COP is about maximum 0.09 in occasion of single effect and is about maximum 0.08 in occasion of double effect series flow. In the case of heat exchanger efficiency is about 0.85, it's increments are 0.08 and 0.072, each. And solution cooling condenser is a more effective device in the single effect absorption system more than double effect system for the principle of operation. In order to increases the heat of solution cooling condenser, if reduce the flow rate of cooling water or the value of UA, it makes COP increase a little, but it brought COP decrease because of increasing the pressure of system.

• Advances in materials Research
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• v.11 no.2
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• pp.165-170
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• 2022

Acrylic resin or polymethylmethacrylate (PMMA) is one of the most attractive materials to be used for dental appliances manufacturing. It has been introduced as a biomaterial during the last century. This study aims to evaluate the compounds absorption and release through acrylic resin to be used for drug delivery as well. The study specimens were 10 pieces of heat-cured clear acrylic resin with dimensions of 10 × 10 × 2 mm. The specimens were dipped in methylene blue solution at a powder-water ratio of 1:20 for 5 days. The samples were removed and dipped in 5 ml distilled water vials for 24 hours. Then the specimens were replaced into new 5 ml vials and the process lasted for 4 days. The extracted solutions were analyzed by the visible light spectroscopy for absorbance. The statistical results showed a gradual increase in stain release from day 1 to day 4 with a significant difference between day 1 and day 4 solutions. The study showed that PMMA resin is able to absorb and release some compounds constantly and the absorption drug-loading technique is applicable to this material.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.854-855
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• 2005

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.184-189
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• 2014

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1604-1615
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• 1969

This experiment was carried out as one of the basic studies to improve the acid resistance of concrete and it was conducted to investigate some relations among physical properties such as basorption, ratio of water to cement, compressive strength, density and ratio of mix to weight losses of mortar when exposed to 0.1 N solution of hydrochrolic acid. The results obtained from the limited data secured so far in this experiment are summarized as follows: 1. The specimens used in the experiment were made of 5 cubic centimeters of mortar having such various ratios of mix by weight as 1 : 1, 1 : 3, 1 : 5, 1 : 7, 1 : 10. 2. Physical tests included compressive strengths at 7 days, 28 days, 3 months, and 6 month, and 5 hour boiling absorption test. 3. In acid test, every specimen was immersed into 0.1 N solution of hydrochrolic acid. The specimens exposed to the acid solution were weighed to determine the weight losses of the acid-corroded at one week interval for 7 weeks exposure, and the old acid solutions were also changed to fresh one when weighed the weight losses by acid attack at one week interval. 4. The correlative relations were found among physical properties and they are expressed by certain formulas as follows; i) Relation between ratio of mix and absorption Y = 1.036x + 13.53 where Y: absorption(%) X: ratio of mix ii) Relation between ratio of mix and ratio of water-cement Y = 0.204x + 0.214 where Y: ratio of water-cement. X: ratio of mix iii) Relation between ratio of water-cement and absorption Y = 5.01x + 12.53 where Y: absorption(%). X: ratio of water-cement iv) Relation between density and absorption Y = 50.6 - 0.0176X where Y: absorption(%). X: density($kg/m^3$) v) Relation between density and ratio of water cement Y = 7.2183 - 0.0033X where Y: ratio of water-cement . X: density($kg/m^3$) 5. After completing the acid exposure test the specimens were corroded and , the per cent ranges of weight losses varies from a minimum of 20.4 per cent at a 1 : 1 mix to a maximum of 92.0 per cent at a 1:10 mix 6. The correlative relations of physical properties of mortar to weight losses by acid attak were found and they are also expressed by certain formulas as follows: i) Relation between weight losses and ratio of mix Y = 8.59X + 8.63 where Y: weight losses(%), X: ratio of mix ii) Relation between wieght losses and absorption Y = 0.121x + 12.43 where Y: absorption(%). X: weight losses(%) iii) Relation between weight losses and ratio of w/c Y = 0.0226X + 0.07 where Y: ratio of w/c X: weight losses(%) iv) Relation between weight losses and compressive strength LogY = 3.6097 - 0.05058X + 0.00022$X^2$ where Y: compressive strength ($kg/cm^3$) X: weight losses(%) v) Relation between weight losses and density Y = 2153.1 - 6.62X where Y: density($kg/m^3$) X: weigh losses(%) 7. In order to make better acid resistant mortar, it could be concluded that a 1 : 3 mix or richer mixes, adequate mixing water to minnimize the ratio of water-cement considering the workability, 16 per cent or less absorption by 5 hour boiling water, 1,800 kilogram per cubic meter or denser density by absolute weight base and 200 kilogram per square meter or compressive strength at 20 day, etc are required so as to obtain acid-resistant mortar. In addition to the above, it might be recommonded to select the fine aggregate and to use better equipments such as a mechanical vibrator, a mechanical mixer etc. in concrete manufacturing works.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.492-497
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• 2014

Artificial fine aggregates (denoted AFA) were fabricated using spent bleaching clay (denoted SBC) generated from processed vegetable oil and stone sludge (denoted SS) produced from crushed aggregate manufacturing materials for use as functional construction materials. Each raw material was crushed to particle size finer than $150{\mu}m$, and fine spherical pellets of approximately 1 ~ 4 mm in diameter were prepared by a pelletizing process. The physical properties of the AFA were measured with different types of sintering equipment. A new type of vertical furnace that sinters fine aggregates in a fluidized bed at high temperatures was designed and tested. AFA sintered in a rotary kiln at $1125^{\circ}C$ showed a bulk density of $1.5g/cm^3$ and a water absorption of 16%. AFA sintered in the vertical furnace at $1125^{\circ}C$ showed a bulk density of $1.9g/cm^3$ and water absorption of 8.5%. The bulk density of the AFA sintered in the vertical furnace showed a bulk density 27% higher and water absorption 47% lower than those of AFA sintered in the rotary kiln.

• Korean journal of food and cookery science
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• v.27 no.6
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• pp.735-743
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• 2011

This study examined physicochemical properties of rice grains and qualities of cooked white rice of the high yielding, Japonica type, specifically Druryechanbyeo and Boramchanbyeo, and of the Tongil-type, specifically Hanarumbyeo and Andabyeo. The changes of water absorption rate of rice grains, their textural properties and a sensory evaluation of the cooked rice s were analyzed. All varieties were short grain. The length and width of Tongil type rice grains larger than those of Japonica type. The water absorption of white rice grains increased rapidly until 1 hr when soaking and after that increased slightly. The water absorption of Druryechan grain was higher than that of the Boramchan. The sensory evaluation results showed that the Japonica type cooked rices had a higher value for overall quality than the Tongil type cooked rices. With regard to the textural properties of the cooked rices, the hardness of Boramchan and Hanarum varieties showed higher than that of Druyechan and Anda varieties. Adhesiveness, springiness and chewiness were not significantly different between varieties (p<0.05).