• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.591-596
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• 2019

A recently developed propellant, ammonium dinitramide (ADN, $NH_4N(NO_2)_2$ is stable and safe at an ambient condition. However, it requires high purity for practical applications. A very little quantity of foreign impurities in ADN may cause clogging of thruster nozzles and catalyst poisoning for the use of a liquid propellant. Thus, several purification processes for precipitated ADN particles such as repetition extraction, activated carbon adsorption and low-temperature extraction were presented in this study. The purifying methods helped to improve the chemical purity as evaluated by FT-IR and UV-Vis spectroscopy in addition to ion chromatography (IC) analyses. Among the purification processes, adsorption was found to be the best, showing a final purity of 99.8% based on relative quantification by IC. Thermal analysis revealed an exothermic temperature of $148^{\circ}C$ for the synthesized liquid monopropellant, but rose to $188^{\circ}C$ when urea was added.

• Journal of Practical Agriculture & Fisheries Research
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• v.7 no.1
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• pp.81-89
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• 2005

The experiment was conducted to evaluate the effect of fruit skin spray of the lime fertilizer in 'Campbell Early' grapes. The T-N, P, K, Ca and Mg of fruit skin and cluster weight, berry weight, cluster length showed no difference between control and lime fertilizer. But soluble solids in fruit was reduced by fruit skin spray of liquid calcium fertilizer extracted from oyster shell after bagging(LCaB). The anthocyanin content of fruit skin was decreased by air-slaked lime(HCa) and LCaB treatment. Also, occurrence of fruit skin bloom was significantly reduced by HCa and oyster shell powder(OS-CaP) treatment. The berry firmness was significantly increased through liquid calcium fertilizer extracted from oyster shell(LCa) and HCa treatment. Conspicuously, berry elasticity was rather decreased by OS-CaP treatment. However, there was no difference of weight loss of fruit among treatments during room temperature storage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.529-536
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• 2011

In this study, we confirmed that the SWRO(Sea Water Reverse Osmosis) production water has more hard corrosiveness than the tap water by fundamental experiment. According to the result, the target of this study was aimed at developing maintenance and anti-corrosion method. In the early stages of the research, batch tests using mild steel coupons and electrochemical experiments were applied to compare the corrosiveness between SWRO production water and the tap water. After then, two corrosion control methods for SWRO production water were applied. Liquid lime($Ca(OH)_2$) and Carbon Dioxide($CO_2$) were inserted and compared with the combination of liquid lime with phosphate corrosion inhibitor and carbon dioxide. The water qualities were evaluated through LSI(Langelier Saturation Index) and proper injection ratio was deduced by the result. Since then, simulated loop system test were performed to evaluate anti-corrosion effect depending on corrosion inhibitors. Subsequently, carbon steel pipes equipped at the loop system were detached for SEM, EDX and XRD analysis to acquire quantitative and qualitative data of the major corrosion products inside the pipes. In conclusion, the controled groups with anti-corrosion techniques applied were effective by appearing 97.4% and 90.9% of improvements in both case of liquid lime and the liquid lime with a phosphate corrosion Inhibitor. furthermore, major components of scale were iron oxides, on the other hand, protective effect of film formation by calcium carbonate($CaCO_3$) could be confirmed.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.167-175
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• 2009

The geology of Sepola district in Mali is consisted of Birrimian group with metasedimentary rocks of lower Proterozoic and volcanoclastics, and later intrusive igneous rocks. Ore diposit in this district has the characteristics of vein- and disseminated-type gold deposit which was formed by infilling the secondary fracture zones related to the large-scale fault zone of NW direction within Birrimian group. It is confirmed as promising that Barani district has the gold grade of 0.53${\sim}$9.21 g/t with the extension of 1.3 km and width of 1 to 20.1 m. The ore mineralogy is simple with electrum, pyrite and galena. Fineness of gold grain ranges from 848 to 915(average 891) indicating mesothermal to hypothermal environment. Fluid inclusions are classified as liquid-rich type I. gas-rich type II and liquid-$CO_2$ bearing type III. Primary and pseudosecondary inclusions homogenize from 236 to 393$^{\circ}C$ with salinity of 0.0 to 8.6 wt% NaCl. Secondary inclusions homogenize from 103 to 184$^{\circ}C$ with salinity of 0.7 to 8.6 wt.%. From the relationship between homogeniztion temperature and salinity, it may be thought that auriferous fluid experienced dilution and cooling through inflow of meteoric water after fluid unmixing derived from pressure decrease in the temperature range of 400 to 250$^{\circ}C$. From the massive occurrence of quartz vein, simple mineralogy with paucity of sulfide, and presence of liquid-$CO_2$ bearing with high homogenization temperature, it is thought that gold mineralization in Sepola district correspods to the mesothermal to hypothermal ore deposit.

• Journal of ILASS-Korea
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• v.12 no.2
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• pp.94-100
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• 2007

The liquid phase LPG injection (LPLi) system (the third generation technology) has been considered as one of the next generation fuel supply systems for LPG vehicles, since it has a very strong potential to accomplish the higher power, higher efficiency, and lower emission characteristics than the mixer type (the second generation technology) fuel supply system. To investigate the characteristics of LPG residue in liquid phase LPG injection system, various rubbers in LPG fuel system were reacted with LPG fuels during 3 months. The experimental results showed that the residue of a cover rubber in a fuel pump after test increased 10 times higher than that before test. Furthermore, the amount of sulfur, nitrogen species which are considered as main sources in deposit formation in the LPLi fuel injector were also found to be higher than that in original LPG fuel. And rubber properties of fuel pump cover were decreased after reaction test compared with those of the original rubber. Therefore, the rubber for fuel pump cover is not suitable for a proper material in LPLi fuel system. And these results can provide more information if a motor company shares the data of core rubber parts in field test LPLi vehicles.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.6
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• pp.685-692
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• 2015

The concern over the risk of environmental exposure to brominated phenols has been increased and has led the researchers to focus their attention on the study of bromophenol treatment. In this study, the effects of pH and ferrate(VI) dose on the degradation of 2-bromophenol were investigated. The results indicated that the oxidation of 2-bromophenol by liquid ferrate(VI) was found to be highly sensitive to the pH condition. Furthermore, the highest removal efficiency was observed at the neutral condition with the removal efficiency of 94.2%. In addition, experimental results showed that 2-bromophenol removal efficiency increased with increasing of ferrate dosage. Ferrate(VI) dose of 0.23 mM was sufficient to remove most of the 2-bromophenol with the efficiency of 99.73% and kapp value of $2982M^{-1}s^{-1}$. Seven compounds were identified as the intermediate products by the GC/MS analysis.

• Journal of Power System Engineering
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• v.13 no.3
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• pp.20-26
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• 2009

디젤기관에서 배출되는 유해배출성분인 NOx(Nitrogen oxides)와 PM(Particulate matter)은 기관 실린더내의 혼합기 분포에 의해 그 생성이 지배된다. 이 때문에 그 유해배출물들을 저감하기 위해서는 연소의 전단계인 혼합기 분포 및 그 생성과정의 해석은 매우 중요하다. 디젤기관에서 노즐로부터 분사된 연료는 주위기체와 혼합기를 형성하는 과정에서 액체에서 기체로 상변화를 동반한다. 따라서 분무의 혼합기형성과정을 해석하기 위해서는 액상과 기상을 동시에 분리하여 계측하는 것이 필요하다. 그러므로 본 연구에서는 디젤분무를 대상으로 Melton 등이 제안한 엑시플렉스(Exciplex) 형광법을 이용하여, 분무의 액상과 기상을 동시에 2차원분리해서 가시화촬영을 행하였다. 그 엑시플렉스 형광법을 이용하여 획득한 이미지에 화상 응용해석을 실시하여 비정상증발디젤분무의 혼합기형성과정에 대한 정보를 얻고자 하였다. 엑시플렉스 형광법을 이용해서 증발분무의 거동측성을 해석한 결과 프랙틸해석을 이용한 분무 흐트러짐(Disturbance)의 평가에서 플랙틸차원은 분사압력의 변화에 관계없이 하나의 값, 약 1.1로 정리 할 수 있고, 그 결과 각 분사압력에 대한 분무 기상외곽곡선(외주)은 거의 동일한 정도의 요철형상을 갖는다.

• Journal of Welding and Joining
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• v.9 no.4
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• pp.28-39
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• 1991

The change of microstructure in the bonded interlayer and mechanical properties of the joints were investigated during Transient Liquid Phase Diffusion Bonding(TLP bonding) of STS304/SM17C and STS304/SM45C couples using Ni base amorphous alloys added boron and prepared alloy as insert metal. Main experimental results obtained in this study are as follows: 1) Isothermal solidification process was completed much faster than theoretically expected time, 14ks at 1473K temperature. Its completion times were 3.6ks at 1423K, 2.5ks at 1473K and 1.6ks at 1523K respectively. 2) As the concentration of boron in the insert metal increased, the more borides were precipitated near bonded interlayer and grain boundary of STS304 side during isothermal solidification process, its products were $M_{23}P(C,B)_6}_3)$ The formation of grain boundary during isothermal solidification process was completed at structural carbon steel after starting the solidfication at STS304 stainless steel. 4) The highest value of hardness was obtained at bonded interface of STS304 side. The desirable tensile properties were obtained from STS304/SM17C, STS304/SM45C using MBF50 and experimentally prepared insert metal with low boron concentration.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.32-37
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• 2008

For a development of U-safety system, liquid/gas-sensors that are easy to carry and install in any place are needed. Therefore, in this work, we prepared porous gold using a templating method with nanoporous alumina, and it was used as sensing materials and electrode. The resulting materials showed high purity macroporous structure with $200{\sim}300\;nm$ of window-pore and $4.8\;m^2/g$ of surface area. Because porous gold had good electric conductivity, convenience to measure the change of electric resistivity and good reproducibility, it could be used as potential sensing materials. As a proof-of-concept test, the detection test for mercury ion was carried out.

• Journal of Animal Environmental Science
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• v.11 no.1
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• pp.17-24
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• 2005

Aerobic sequencing batch reactor (SBR) was used to treat screened dairy wastewaters. The study examined the production of volatile organic compounds (VOCs) and volatile fatty acids (VFAs) in the aerobic SBR and raw manure effluent storage over 35 days. The reduction of total VFAs in the aerobic SBR was over $59\%$ removal than that of the raw manure. Acetic acid production in the aerobic SBR and the raw manure effluent storage were kept 138 and 286 mg/L. The propionic acid in the aerobic SBR was 1.9 mg/L, while the raw manure effluent storage was 68 mg/L, respectively. The concentrations of VOCs in the aerobic SBR reactor and effluent fill down remarkably than the raw manure storage. The results confirmed that the aerobic biological treatment is an essential requirement for minimizing odor problems.