• The Journal of the Petrological Society of Korea
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• v.18 no.4
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• pp.279-291
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• 2009

Radon is a natural radionuclide originated from radioactive decay of radium in rocks and soil. It is colorless, odorless and tasteless elements that mainly distributed as gaseous phase in soil pore space. The present study analyzed the characteristics of long-term radon variation in granitic residual soil at Mt. Guemjeong in Guemjeong-gu, Busan and determined the effects of atmospheric temperature, rainfall and soil temperature and moisture. Periodic measurements of radon concentrations in soil gas were conducted by applying two types of in-situ monitoring methods (chamber system and tubing system). Radon concentration in soil gas was highest in summer and lowest in winter. The variations in soil temperature and atmospheric temperature were most effective factors in the long-term radon variations and showed positive co-relations. The air circulation between soil air and atmosphere by the temperature difference between soil and atmosphere was analyzed a major cause of the variation. However, other factors such as atmospheric pressure, rainfall and soil moisture were analyzed relatively less effective.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.6
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• pp.812-817
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• 2012

Nitrate can serve as a terminal electron acceptor in place of carbon dioxide and inhibit methane emission in the rumen and nitrate reducing bacteria might help enhance the reduction of nitrate/nitrite, which depends on the type of feed offered to animals. In this study the effects of three levels of sodium nitrate (0, 5, 10 mM) on fermentation of three diets varying in their wheat straw to concentrate ratio (700:300, low concentrate, LC; 500:500, medium concentrate, MC and 300:700, high concentrate, HC diet) were investigated in vitro using buffalo rumen liquor as inoculum. Nitrate reducing bacteria, isolated from the rumen of buffalo were tested as a probiotic to study if it could help in enhancing methane inhibition in vitro. Inclusion of sodium nitrate at 5 or 10 mM reduced (p<0.01) methane production (9.56, 7.93 vs. 21.76 ml/g DM; 12.20, 10.42 vs. 25.76 ml/g DM; 15.49, 12.33 vs. 26.86 ml/g DM) in LC, MC and HC diets, respectively. Inclusion of nitrate at both 5 and 10 mM also reduced (p<0.01) gas production in all the diets, but in vitro true digestibility (IVTD) of feed reduced (p<0.05) only in LC and MC diets. In the medium at 10 mM sodium nitrate level, there was 0.76 to 1.18 mM of residual nitrate and nitrite (p<0.01) also accumulated. In an attempt to eliminate residual nitrate and nitrite in the medium, the nitrate reducing bacteria were isolated from buffalo adapted to nitrate feeding and introduced individually (3 ml containing 1.2 to $2.3{\times}10^6$ cfu/ml) into in vitro incubations containing the MC diet with 10 mM sodium nitrate. Addition of live culture of NRBB 57 resulted in complete removal of nitrate and nitrite from the medium with a further reduction in methane and no effect on IVTD compared to the control treatments containing nitrate with autoclaved cultures or nitrate without any culture. The data revealed that nitrate reducing bacteria can be used as probiotic to prevent the accumulation of nitrite when sodium nitrate is used to reduce in vitro methane emissions.

• Journal of the Korean Vacuum Society
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• v.11 no.2
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• pp.87-96
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• 2002

Outgassing from such sources as paints, coatings, adhesives and other non-metallic surfaces can contaminate satellites, especially second surface mirror and optical lens, it cause satellite to fail in own missions. The vacuum bake-out test using high temperature(more than $85 ^{\circ}C$)and high vacuum(less than $5.0{\times}1-^{-3}$ Pa) certify that the components of satellite work properly and can survive and operate in space environment like high vacuum. In the bake-out chamber installed at SITC of KARI, Rotary vacuum pump and Booster pump produce low vacuum of 5.0 Pa, and then two cryopumps produce high vacuum of below $5.0{\times}10^{-3}$ Pa. Also 48 ceramic heaters were provided to simulate high temperature. During the vacuum bake-out test, we detected contaminants using RGA(Residual Gas Analyzer) and measure the outgassing rate of the contaminant using the TQCM(Thermoelectric Quartz Crystal Microbalance). Also, IR/UV Spectrometer and witness plate be used to certify that the components were suitable for the spacecraft. This paper includes the preparation and procedures of the bake-out test for SAR(Solar Array Regulator) and MLI(Multi Layer Insulator), which were the components of the spacecraft. Especially, we discussed the methods and results of the contamination measurement. In the bake-out for SAR, the contamination was measured continuously although it was on the decrease from TQCM results. And RCA established that it is a highly polymerized compound. In the MLI bake-out using RGA and witness plate, we didn't detect any contamination materials.

• Korean Journal of Materials Research
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• v.4 no.8
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• pp.934-944
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• 1994

Effects of residual chloride on thermal decomposition behaviour of a-stannic acid and physical properties of $SnO_{2}$ powder were observed. The powder was fabricated by hydroxide method; $\alpha$-stannic acid was precipitated by mixing acqueous solutions of $SnCl_{4}$ and $NH_{4}$OH . The precipitate was washed with $NH_{4}NO_{3}$ solution while washing was controlled to be of three grades to modify its residual chloride content. The precipitate was dried at $1100^{\circ}C$ ~ 24h and calcined in air at $500^{\circ}C$ ~ $1100^{\circ}C$ for one hour. Thermal decomposition behaviour of $\alpha$-stannic acid was examined by a DT-TGA and a FTIR. Chemical composition and physical properties of $SnO_{2}$ powder were observed by an AES, a BET and a TEM, respectively. With a reduction in chloride content, the relative crystallite size of $SnO_{2}$ powder slightly increased by a low-temperature-calcining. However, at a high calcining temperature(T), the reverse relation occured. It was suggested that chloride ion replaces part of lattice oxygen site of a-stannic acid. Also, chloride ion on the site was suggested to retard de-hydration as well as crystalization at a low T while to promote crystal growth of $SnO_{2}$ by forming oxygen vacancy at a high T.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.928-934
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• 2002

Gallium doped Zinc Oxide(GZO) films were deposited by dc magnetron sputtering using a GZO ceramic target at various conditions such as substrate temperature (RT, 400), residual water pressure ($P_{H_2O}$; 1.61${\times}10^{-4}∼2.2{\times}10^{-3}$ Pa), introduction of $H_2$ gas (8.5%) and different magnetic field strengths(250, 1000G). GZO films deposited without substrate heating showed clear degradation in film crystallinity and electrical properties with increasing $P_{H_2O}$. The resistivity increased from 3.0${\times}10^{-3}$ to 3.1${\times}10^{-2}{\Omega}㎝$ and the grain size of the films decreased from 24 to 3 nm when PH2O was increased from 1.61${\times}10^{-4}$ to 2.2${\times}10^{-3}$ Pa. However, degradation in electrical properties with increasing $P_{H_2O}$ was not observed for the films deposited with introduction of 8.5% $H_2$. When magnetic field strength of the cathode increased from 250G to 1000G, crystallinity and electrical properties of GZO films improved remarkably about all the $P_{H_2O}$. This result could be attributed to the decrease in film damage caused by the decrease in plasma impedance.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.4
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• pp.111-116
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• 2001

As part of the recycling methods, residual food through the anaerobic fermentation process was decomposed into methane gas and fermentation liquid. The research was conducted to measure the effect of application of fermentation liquid on chemical properties of soil and plant growth according to application rate and separate manure at the base of nitrogen in fermentation liquid. The fermentation liquid contained 0.52% nitrogen was applied in treatments by standard fertilizer. The treatments were composed of the control only with chemical fertilizer and N-50, N-100-4, N-100-8 were each of applied with 50, 100(6 times), 100(3 times)% of fermentation liquid contrast to standard fertilizer. Properties of fermentation liquid was high EC because of waster soluble organic compounds as well as much of salts and also contained a lot of suspended solid. The changes of soil chemical properties little occurred in before and after of experiment but EC and content of ex. Ca in soil were increased. Fresh weigh in treatments applied with fermentation is high than that of control but the difference between treatments little showed. The above result means if fermentation liquid be used instead of chemical fertilizer the volume of used fermentation liquid will be reduced by 50% of present standard fertilizer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1179-1185
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• 2011

Cold and hot-rolled carbon steel sheets are commonly used in railroad cars or commercial vehicles such as the automobile. The sheets used in these applications are mainly fabricated by spot welding, which is a type of electric resistance welding. However, the fatigue strength of a spot-welded joint is lower than that of the base metal because of high stress concentration at the nugget edge of the spot-welded part. In particular, the fatigue strength of the joint is influenced by not only geometrical and mechanical factors but also the welding conditions for the spot-welded joint. Therefore, there is a need for establishing a reasonable criterion for a long-life design for spot-welded structures. In this thesis, ${\Delta}P-N_f$ relation curves have been used to determine a long-life fatigue-design criterion for thin-sheet structures. However, as these curves vary under the influence of welding conditions, mechanical conditions, geometrical factors, etc. It is very difficult to systematically determine a fatigue-design criterion on the basis of these curves. Therefore, in order to eliminate such problems, the welding residual stresses generated during welding and the stress distributions around the weld generated by external forces were numerically and experimentally analyzed on the basis of the results, reassessed fatigue strength of gas welded joints.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.98-103
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• 2017

In this study, contributes to improving the state of this problem using cavitation by ultrasonic energy to reduce fuel costs, which take up a considerable part of ship operation costs, by making the use of on-board blended fuel oil more stable. An experiment simulating on-board blending methods was completed. Fuel (M.G.O & MF-180) was mixed at a volume ratio of 0.25:0.75 and, 0.75:0.25, and the effect of ultrasonic energy on blended fuel oil was examined after applying ultrasonic energy to blended fuel oil using an ultrasonic treatment unit. With the results, we confirmed the blending problem reported by vessels and residual carbon was reduced by up to 28.4%. In addition, based on the results for reduction of residual carbon content and dispersion stability, it was confirmed that the collapse pressure of the cavity due to the ultrasonic energy was effective to atomization of fuel particle and the temporary availability of mixed fuel containing a heavy fuel increased.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.131.1-131.1
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• 2010

This study was conducted for engineering optimization for the gasification process which is the key factor for success of Taean IGCC gasification plant which has been driven forward under the government support in order to expand to supply new and renewable energy and diminish the burden of the responsibility for the reduction of the green house gas emission. The gasification process consists of coal milling and drying, pressurization and feeding, gasification, quenching and HP syngas cooling, slag removal system, dry flyash removal system, wet scrubbing system, and primary water treatment system. The configuration optimization is essential for the high efficiency and the cost saving. For this purpose, it was designed to have syngas cooler to recover the sensible heat as much as possible from the hot syngas produced from the gasifier which is the dry-feeding and entrained bed slagging type and also applied with the oxygen combustion and the first stage cylindrical upward gas flow. The pressure condition inside of the gasifier is around 40~45Mpg and the temperature condition is up to $1500{\sim}1700^{\circ}C$. It was designed for about 70% out of fly ash to be drained out throughout the quenching water in the bottom part of the gasifier as a type of molten slag flowing down on the membrane wall and finally become a byproduct over the slag removal system. The flyash removal system to capture solid particulates is applied with HPHT ceramic candle filter to stand up against the high pressure and temperature. When it comes to the residual tiny particles after the flyash removal system, wet scurbbing system is applied to finally clean up the solids. The washed-up syngas through the wet scrubber will keep around $130{\sim}135^{\circ}C$, 40~42Mpg and 250 ppmv of hydrochloric acid(HCl) and hydrofluoric acid(HF) at maximum and it is turned over to the gas treatment system for removing toxic gases out of the syngas to comply with the conditions requested from the gas turbine. The result of this study will be utilized to the detailed engineering, procurement and manufacturing of equipments, and construction for the Taean IGCC plant and furthermore it is the baseline technology applicable for the poly-generation such as coal gasification(SNG) and liquefaction(CTL) to reinforce national energy security and create new business models.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.55-66
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• 2012

The practical way to minimize the greenhouse gas is to reduce the emission of carbon dioxide. For this reason, CCS(Carbon Capture and Storage) technology, which could reduce carbon dioxide emission, has risen as a realistic alternative in recent years. In addition, the researcher is recently working into ways of applying CCS technologies with deep saline aquifer. In this study, the evaluation model on the feasibility of $CO_2$ sequestration in the deep saline aquifer using ANN(Artificial Neural Network) was developed. In order to develop the efficiency-evaluation model, basic model was created in the deep saline aquifer and sensitivity analysis was performed for the aquifer characteristics by utilizing the commercial simulator of GEM. Based on the sensitivity analysis, the factors and ranges affecting $CO_2$ sequestration in the deep saline aquifer were chosen. The result from ANN training scenario were confirmed $CO_2$ sequestration by solubility trapping and residual trapping mechanism. The result from ANN model evaluation indicated there is the increase of correlation coefficient up to 0.99. It has been confirmed that the developed model can be utilized in feasibility of $CO_2$ sequestration at deep saline aquifer.