• Korean Journal of Soil Science and Fertilizer
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• v.15 no.3
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• pp.188-193
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• 1982

Granulation formed from mixture of sulfate of potash (SOP) powder and pulverized silica minerals (Zeolite, Serpentine and Talc) was studied to establish granulation rate and physical properties of granules. These mixtures were granulated in a pan granulator with water and granules of SOP were coated with minerals powder. Mixture of SOP and mineral powder by half (w/w) were increased granulation rate compared with pure SOP powder, and talc was superior to them with SOP. Water was needed about 14% to granulate SOP powder alone, but it decreased by 2% with talc and increased by 4% and 2% with zeolite and serpentine, respectively. Granules of mixture of SOP with zeolite were harder than pure SOP granules but with another minerals powder decreased in hardness. Also breaking rate of granules in vinyl parcel falling from 2m height and abrasion rate of granules by agitation were improved by mixing and coating with zeolite but with the other were of inferior.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8637-8642
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• 2015

Typical aging for the rubber using the current military adhesive combat boots was spread with a regular aging caused by heat stress. In this study, the aging test of the rubber for combat boots was carried out and the reaction rate constant, k was calculated at aging temperature $60^{\circ}C$, $80^{\circ}C$ and $100^{\circ}C$, using the Arrhenius equation. The lifetime limit was assumed that the tensile strength of the product is reduced to 30%, the elongation is reduced to 50% and abrasion resistance ratio is 380%. ln($P/P_0$) and the lifetime was predicted with the consideration of the activation energy constant. According to the above, the lifetime of the rubber for combat boots with influenced by aging temperature was predicted. As the result, the estimate lifetime at $20^{\circ}C$ was confirmed more than 10 years.

• Journal of Veterinary Clinics
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• v.10 no.2
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• pp.227-235
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• 1993

The effectiveness of sodium carboxymethylcellulose(SCMC) and dextran 70 in the prevention of adhesion formation in abdominal cavity of rabbits following artificial injuries was elucidated and the effects -of these medicines on blood pictures were also examined. After abrasion treatment on jejunum in gonadotropins primed rabbits, 1, 2 and 3% of SCMC solutions, 6 and 10% dextran 70 solutions and a synthetic solution of 1% SCMC and loft dextran 70 in 0.9% saline solution were infused into the abdominal cavity. Four weeks later the abdominal cavities were reopened under general anesthesia. The synthetic solution showed the highest adhesion reduction rate(100%), while 1% SCMC, 6 and loft dextran solutions showed no significantly evident effect of adhesion prevention. The SCMC solutions showed better adhesion reduction effect than dextran 70 solutions. After infusion of these adhesion preventive medicines, the changes of total leucocytes, erythrocytes, lymphocytes, PCV, plasma fibrinogen and protein contents were examined. No remarkable difference in blood pictures was shown between the synthetic solution and the other medicines. Therefore, it can be suggested that the synthetic solution of 1% SCMC and 10% dextran 70 in 0.9% saline solution at dose of 5$m\ell$/kg of body weight is prominently effective in the prevention of postoperative adhesion formation and wolf be safe in animals and human.

• Journal of Veterinary Clinics
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• v.10 no.2
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• pp.203-214
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• 1993

With the use of a rat surgical model, the ability of carboxymethylcellulose and ibuprofen in the reduction of abdominal adhesion was examined. Seventy seven female rats were randomly divided into 7 groups : (1) control, (2) 2% CMC, (3) 3% CMC, (4) ibuprofen 25mg, (5) ibuprofen 50mg, (6) combination of ibuprofen 25mg and 2% CMC and(7) combination of ibuprofen 50mg and 3%, CMC. Following induction of abrasion injuries on ileum, colon and both uterine horns with a surgical blads, the rats in groups (2), (6) were infused with 2% CMC solution singly or in combined Infection of 25 mg/kg of ibuprofen for three consecutive days, the rats In groups (3), (7) were infused with 3% CMC solution singly or In combined Injection of 50mg/kg of ibuprofen for three consecutive days. The rats in groups (4), (5) were injected only with 25 mg or 50 mg/kg of ibuprofen for three consecutive days. After 10 days the abdominal cavities were opened and the appearance of formed adhesion were graded. The changes of body weight, CBC and blood chemicals were also evaluated at 3, 6 and 10 days after operation. In ileum, the rats in the groups (2), (6) and (7) showed less adhesion formation. In colon, there were significant differences(p<0.05) in adhesion formation in all treated groups as compared to control. In both uterine horns, there were significant decrease(p<0.05) of adhesion formation in groups(2), (6) and (7) in comparison with other groups. The increasing rate of body weight was evident in group (3) and fibrinogen concentrations at 6 and 10 days revealed significant decrease (p<0.01) in group (7), whereas there was no consistent change in CBC and blood chemicals. Therefore, it can be sugested that the infusion of 2% CMC solution with or without the injection of 25 mg/kg of ibuprofen and 3% CMC solution with the injection of 50 mg/kg of ibuprofen are effective and safe following abdominal surgery,

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.127-134
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• 1993

The purpose of this study was to observe the control effect of hypersensitivity after periodontal treatment in the 19% microcrystalline hydroxyapatite containing toothpaste for the subject of 85 persons of both sexes, who complained hypersensitivity. At 2 weeks and 4 weeks after periodontal treatment, comparison of control effect was performed between the 19% microcrystalline hydroxyapatite containing toothpaste group and control group. The result were as follows, 1. The main causes of dentin hypersensitivity are the root exposure with gingival recession and cervical abrasion. 2. The occurance rate of hypersensitive tooth in the upper jaw was higher than that of the lower jaw, and more or less, the molar area showed more occlurance of hypersensitivity than the premolar and incisor area in both jaw. 3. Patients showed very sensitive response to the thermal stimulus, especially cold stimulus. 4. Exellent control effect of hypersensitivity in 19% microcrystalline hydroxyapatite containing toothpaste group showed 83.02% at 2weeks, 92.45% at 4weeks and these values were higher than the control group. In conclusion, we find that 19% microcrystalline hydroxyapatite containing toothpaste have the control effect of hypersensitivity and the proper toothbrushing method is the key in attaining more effectiveness of the toothpaste.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.292-299
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• 2017

The KUH-1's Wheel Brake Assembly which is Brake System is an essential component to perform flight mission for pilot. It has function of taxing, differential braking and parking to sustain landing capability. However, the skid and abrasion of tire were occurred in mass-produce operation. Also, if it is occurred on the ground, the flight can not be performed. In this case, the defect is a major cause of the decrease in the operation rate of aircraft. In this paper, the cause of the defect in flight was identified and the failure process was organized. Also, it describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5157-5164
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• 2010

Currently about 3.2 millon tons of waste lime are accumulated and annually 100,000 tons are producted. This study was carried out to investigate the characteristics of soil mixed with waste lime for reusing of roadbed embanking material. Waste lime used in this study is producted as a by-product in the manufacturing process of making $Na_2CO_3$ from local chemical factory in Incheon. In this study, the feasible reuse of waste lime mixed with granite weathered soil, clay, crushed rock was investigated through laboratory tests including specific gravity test, sieve analysis, hydrometer analysis, atterberg limit test, compaction test, unconfined compressive test, CBR test, permeability test, shear test, and abrasion test. The mixing rate is granite weathered soil, clay, crushed rock 80 % respectively and waste lime 20 % by weight. From the test results, it is shown that the waste lime and soil mixtures satisfy the criteria as road embanking material specification.

• International Journal of Highway Engineering
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• v.20 no.2
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• pp.19-25
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• 2018

PURPOSES : This purpose of this study is to analyze the effect to autogenous shrinkage of the top-layer material of a two-lift concrete pavement mixing both silica fume and polymer powder. METHODS : The bottom-layer of a two-lift concrete pavement was paved with original portland cement (OPC) with a 20~23 cm thickness. Additionally, the top-layer which is directly exposed to the environment and vehicles was paved with a high-performance concrete (HPC) with a 7~10 cm thickness. These types of pavements can achieve a long service life by reducing joint damage and increasing the abrasion and scaling resistance. In order to integrate the different bottom and top layer materials, autogenous shrinkage tests were performed in this study according to the mixing ratio of silica fume and polymer powder, which are the admixture of the top-layer material. RESULTS : Autogenous shrinkage decreased when polymer powder was used in the mix. Contrary to this, autogenous shrinkage tended to rise with increasing silica fume content. However, the effects were not significant when small amounts of polymer powder were used (3% and 11%). CONCLUSIONS : The durability and compressive strength increase when silica fume is used in the mix. The flexural strength considerably increases and autogenous shrinkage of concrete decreases when polymer powder is used in the mix. As seen from above, the proper use of these materials improves not only durability, but also autogenous shrinkage, leading to better shrinkage crack control in the concrete.

• Journal of the Korean Ceramic Society
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• v.54 no.4
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• pp.292-297
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• 2017

${\beta}-SiAlON$, based on its high fracture toughness, good strength and low abrasion resistance, has been adopted in several industrial fields such as bearings, turbine blades and non-ferrous metal refractories. In general, ${\beta}-SiAlON$ is fabricated by reactive sintering using expensive $Si_3N_4$ and AlN as starting materials. On the other hand, in this study, a cheaper ${\beta}-SiAlON$ starting powder synthesized by SHS was employed to improve price competitiveness compared to that of the reactive sintering process. ${\beta}-SiAlON$ ceramics with various content of the sintering additive $Y_2O_3$ up to 7 wt% were fabricated by conventional pressureless sintering at $1800^{\circ}C$ for 2 to 8 h under $N_2$ pressure of 0.1 MPa. The specimen with 3 wt% $Y_2O_3$ exhibited the best mechanical properties: hardness of 14 GPa, biaxial strength of 830 MPa, fracture toughness of $5MPa{\cdot}m^{1/2}$ and wear rate of about $3{\times}10^{-6}mm^3/N{\cdot}m$.

• Fashion & Textile Research Journal
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• v.11 no.5
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• pp.764-770
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• 2009

This study was conducted to analyze the wearing condition on gloves for pilots and to suggest the developments for pilot gloves design. This survey was performed with 99 pilots and the questionnaires included items about discomfort, materials and problems when wearing pilot gloves. The respondents felt uncomfortable on the finger tip, the hollow area of the hand and the end of thumb when they move their hands with the gloves. They replied that the finger length, palm length, and circumference of the fingers did not match well. Also they complained there was severe abrasion in the tip of the thumb, finger tips and the middle of the palm of the gloves. The result of these analyses supports the following suggestions. It is necessary to improve durability by applying the additional materials to the severely worn parts. Punching on the glove materials could improve sweat rate and ventilation, and careful washing should be accompanied to prevent the occurrence of linters and transformation after laundering. And it is needed to prepare an accurate and more diversified size system and to design the gloves fitted to the individual hands. With these in mind, it is required to propose solutions for pilot gloves with reference to the survey results in order to design appropriate pilot gloves in terms of movement, size and material. It was concluded that an analysis of the wearing condition and developments are useful for ergonomics pilot gloves design.