• Clean Technology
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• v.20 no.1
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• pp.1-6
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• 2014

$CO_2$ is generated by the combustion reaction, when getting the energy from fossil fuel. If the carbon dioxide emissions increases more, the global warming problem will become more serious. CCS (carbon capture storage) needs to be developed for the prevention of this. When liquefied $CO_2$ is transported, BOG (boil-off gas) is generated because of several problems. In the study, by injecting liquefied $CO_2$ in two tanks which contains $40m^3$each, the amount of BOG and its composition were measured during 30 days when generating pressure changes and external heat, loading, unloading. In result, 16,040 kg of BOG was generated and the composition has been found out to be 99.95% $CO_2$ and 0.05 % $N_2$. Also, we conducted simulation process for reliquefaction of generated BOG with vapor compression cycle using the PRO/II with PROVISION version 9.2. As a result, the refrigeration cycle of the total circulation flow rate was 42.07 kg/h and the condenser utility consumption was 48.85 kg/h.

• Journal of Astronomy and Space Sciences
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• v.26 no.2
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• pp.171-186
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• 2009

Various Earth-Moon transfer trajectories are designed and analyzed to prepare the future Korea's Lunar missions. Minimum fuel trajectory solutions are obtained for the departure year of 2017, 2020, 2022, and every required mission phases are analyzed from Earth departure to the final lunar mission orbit. N-body equations of motion are formulated which include the gravitational effect of the Sun, Earth and Moon. In addition, accelerations due to geopotential harmonics, Lunar J2 and solar radiation pressures are considered. Impulsive high thrust is assumed as the main thrusting method of spacecraft with launcher capability of KSLV-2 which is planned to be developed. For the method of injecting a spacecraft into a trans Lunar trajectory, both direct shooting from circular parking orbit and shooting from the multiple elliptical intermediate orbits are adapted, and their design results are compared and analyzed. In addition, spacecraft's visibility from Deajeon ground station are constrained to see how they affect the magnitude of TLI(Trans Lunar Injection) maneuver. The results presented in this paper includes launch opportunities, required optimal maneuver characteristics for each mission phase as well as the trajectory characteristics and numerous related parameters. It is confirmed that the final mass of Korean lunar explorer strongly depends onto the initial parking orbit's altitude and launcher's capability, rather than mission start time.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1177-1192
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• 2018

The objective of this study is to develop the existing drainage system for catching the partial leakage of tunnel structures operating in cold region. The drainage system consists of drainage board, Hotty-gel as a waterproofing material, cover for preventing protrusion of Hotty-gel, air nailer, fixed nail, pipe for collecting ground leak, pipe for conveying ground leak, wire-mesh, and sprayed cement mortar. The drainage systems were installed in conventional concrete lining tunnels to evaluate the site applicability and constructability. The performances of waterproof and the drainage in the drainage system were evaluated by injecting 1,000 ml of red water in the back of the drainage system at 7 days, 14 days, 21 days, 28 days, 2 months, 3 months, 4 months, 5 months, 6 months, 7 months and 8 months. During 8 months of field test, the average daily temperature of the tunnel site was measured from $-16.0^{\circ}C$ to $25.6^{\circ}C$. The daily minimum temperature was $-21.3^{\circ}C$ and the daily maximum temperature was $30.8^{\circ}C$. There was no problem in waterproof and drainage performance of the drainage board in the drainage system. However, the pipe for conveying ground leak had the leakage problem from 14 days. It is considered that the leakage of the pipe for conveying ground leak was caused by the deformation of the pipe of the flexible plastic material having a thickness of 0.2 cm by using the high pressure air nailer and the fixing pin and the insufficient thickness and width of the hotty-gel for preventing the leakage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.460-468
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• 2021

This study investigated the enhanced combustion efficiency of an "air-cooled combustion system" with single F.D. fan, and performed a numerical analysis for the operation and design conditions to increase the combustion efficiency. The combustion efficiency in an actual combustor was compared before and after the structure modification. Numerical analysis for application of a single fan revealed the difficulty of forming a turbulence for circular combustion conditions. This is because the supply ratio of combustion air supplied into 2 flow paths becomes irregular in the combustion furnace due to a change in friction force and pressure in each flow path. Subsequently, two methods of supplying air into the combustion furnace were analyzed numerically to obtain the optimal combustion conditions of an air-cooled combustion system. The first method involved injecting the preheated combustion air after a 180~360 degree rotation from the outer wall, whereas in the second method, the combustion air was injected into the combustion furnace in a tangential direction after primary heat exchange outside the combustion furnace, by applying a rotatable vane structure in the combustion furnace. Results reveal that application of a single F.D. fan to the air injection into a rotatable combustion furnace is desirable for optimization of the combustion conditions for applying a duct structure having a dual cooling wall for the cooling of the outer wall of the combustion furnace, and for maintaining perfect mixing in the combustion furnace. We therefore confirmed enhanced combustion efficiency by comparing the actual combustion efficiency before and after structure modification.

• Journal of the Korean GEO-environmental Society
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• v.25 no.6
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• pp.5-12
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• 2024

Currently, a grouting method that minimizes damage to the reservoir embankment by injecting solidification agent at low pressure is commonly used to ensure waterproofing and safety of the embankment, but the use of solidification agents can cause issues, such as a decrease in durability and a lack of clear method for determining the mixing ratio. In this study, when the base ground and solidification agent were stirred and mixed at various weight mixing ratios, the permeability coefficient and strength of the mixture were confirmed through laboratory tests, and the optimal mixing ratio was suggested through analysis of the test results. The specimen for the laboratory test was produced considering the mixing ratio of the solidification agent. The specimen for the permeability coefficient test was tested by producing one each of cohesionless and cohesive soil for a mixing amount of 1.5 kN/m³ of solidification agent, and the permeability test results confirmed that the water barrier performance was secured below the permeability coefficient value required by various design criteria. A total of 24 specimens for the strength test were produced, 3 for each of 5 mixing amounts for cohesive soil and 3 mixing amounts for cohesionless soil. The strength test results showed that the uniaxial compressive strength tends to increase linearly with increasing curing time for both cohesionless soil and cohesive soil when the mixing amount is less than 2.0 kN/m³. Therefore, the optimal mixing ratio applied to the site is determined to be mixing amount of 1.5 kN/m³ and 2.0 kN/m³. Finally, numerical analysis reflecting test results was conducted on design case for improvement projects for aging reservoirs embankment to verify the water barrier performance and safety improvement effects.

• Journal of Pharmacopuncture
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• v.5 no.1 s.8
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• pp.113-133
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• 2002

Objective: To investigate effects of Cervi Cornu on Adjuvant Athritis in rats, the edema inhibit rate, the anaJgesic effects, the number of WBC, RA facter, Platelet, the quantity of CRP, total protein, albumin and globuline in the blood serum were measured in the arthritis part. Results: The results obtained as fonows ; 1. After arthritis of Sprague dawley(SD) rats was induced by injecting Freund's complete adjuvant for 2 weeks, any treatment was not for Control group, acupunctured for Treat Ⅰ group. normal saJine was ora] administrated for the Treat Ⅱ group, Cervi Cornu Ex. was oral administrated for Treat Ⅲ, and Cervi Cornu Herbal-acupullcture was injected for Trea Ⅳ group during 2 weeks every other day. Selected point was on pressure pain point in both groups. And then the edema inhibit rate were checked. The edema inhibit rate was $46.03\%$ in Treat I group, $43.24\%$ Treat IV group, $37.44\%$ in Treat III. there was significance in the edema inhibit rate between Control group and Treat group, in order of Treat Ⅰ, Ⅳ, Ⅲ.(p<0.05) 2. The analgesic effects was $7.58{\pm}1.80$(${\times}10$gm) in Control group. $11.00{\pm}1.10$(${\times}10$gm) in Treat Ⅰ group. $99.92{\pm}1.28$(${\times}10$gm) in Treat Ⅲ group and $14.67{\pm}1.03$(${\times}10$gm) in Treat Ⅳ group. There was significance in the analgesic effects between Control group and Treat group(p<0.05) 3. The number of WBC was $14.72{\pm}1.48$(${\times}10^3$㎕) in control Group, $10.26{\pm}1.13$(${\times}10^3$㎕) in Treat Ⅰ group, $11.00{\pm}1.13$(${\times}103$㎕) in Treat Ⅱ Group and $9.63{\pm}1.75$(${\times}10^3$㎕) in Treat Ⅳ group. There was significance in the number of WBC between Control group and Treat group(p<0.05) 4. The content of total protein in the blood serum were $6.13{\pm}0.05$g/dl in control group, $5.73{\pm}0.14$g/dl in Treat I group, $5.88{\pm}0.13$g/dl in Treat Ⅲ group and $5.90{\pm}0.13$g/dl in Treat IV group. There was significance in The content of total protein in the blood serum between Control group and Treat group(p<0.05) 5. The contests of albumin in the blood serum were $2.32{\pm}0.12$g/dl in the Control group, $2.35{\pm}0.05$g/dl in Treat Ⅰ group, $2.35{\pm}0.05$g/dl in Treat Ⅱ group, $2.30{\pm}0.06$g/dl in Treat Ⅲ group, $2.42{\pm}0.08$g/dl in Treat IV group. There was no significance in The content of albumin in the blood serum between Control group and Treat group(p<0.05) 6. The contests of globulin in the blood semm were $3.68{\pm}0.08$g/dl in the Control group, $3.43{\pm}0.12$g/dl in Treat Ⅰ group, $3.55{\pm}0.10$g/dl in Treat IV group. There was significance in The content of globulin in the blood serum between Control group and Treat group(p<0.05) 7. The numbers of RA factor were $3.47{\pm}0.54$IU/ml in Control group and $2.38{\pm}0.50$IU/ml in Treat Ⅱ group. There was significance inThe numbers of RA factor between Control group and Treat group(p<0.05) 8. The numbers of platelet were $1126.33{\pm}1126.33{\pm}85.93{times}10^3$/㎕ in Control group, $1043.33{\pm}80.80{times}10^3$/㎕ in Treat Ⅰ group, $1116.82{\pm}77.93{times}10^3$/㎕ in Treat Ⅱ group, $1164.17{\pm}94.02{times}10^3$/㎕l in Treat Ⅲ group, $1076.67{\pm}54.84{times}10^3$/㎕ in Treat Ⅳ group. There was no significance in The numbers of platelet between Control group and Treat group(p<0.05) 9. The quantity of CRP were $0.05{\pm}0.01$mg/ml in Control group, $0.05{\pm}0.01$mg/ml in Treat Ⅰ group, $0.06{\pm}0.01$mg/ml in Treat Ⅱ group, $0.05{\pm}0.00$mg/ml in Treat Ⅲ group, $0.05{\pm}0.00$mg/ml in Treat Ⅳ group. There was no significance in The quantity of CRP between Control group and Treat group(p<0.05) Concluslon : From these results, it is shown Cervi Comu Herbal-acupuncture more efffective thaJJ Cervi Cornu Ex. on Adjuvant Arthritis in rats.

• Journal of dental hygiene science
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• v.15 no.3
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• pp.259-264
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• 2015

For this experiment, specimen was manufactured by injecting polymer and monomer into silicon mold with volume ratio of 2.5:1 based on ISO 20795-2 so that average thickness, width and length of specimen would be maintained as 3.3 mm, 10.0 mm and 65.0 mm, respectively depending on spray on technique. Specimen was divided into 3 groups ($25^{\circ}C$, $40^{\circ}C$, $70^{\circ}C$) depending on polymerization temperature and 10 specimen was manufactured for each group and it was polymerized in water tank of ${\pm}1^{\circ}C$ under the setting condition of polymerization time of 15 minutes and pressure of 3 bar. After keeping specimen in distilled water of $37^{\circ}C$ for over 48 hours before experiment, flexural strength (FS) and elasticity modulus (EM) of specimen being tested by using Intron (3344; Instron; Instron). SPSS ver. 16.0 was used for analysis and post-hoc test of Scheffe was performed after using one-way ANOVA. When comparing mean value of FS of resin for orthodontics, it was represented in the range of 71.500 MPa for $25^{\circ}C$ group, 74.920 MPa for $40^{\circ}C$ group and 76.880 MPa for $70^{\circ}C$ group and difference was shown in the order of $25^{\circ}C$ group <$40^{\circ}C$ group <$70^{\circ}C$ group but such difference was not significant statistically (p=0.052). Result of EM mean value of resin for orthodontics was more polymerization temperature was high, the more was significant difference represented in the order of $25^{\circ}C$ group <$40^{\circ}C$ group <$70^{\circ}C$ group (p<0.039).