• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.112-118
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• 2012

In this study, physical properties of synthesized DE7-OSA82-AO and DEP52-OSA82-AOQ82 zwitterionic surfactants were measured such as critical micelle concentration, surface tension, interfacial tension, contact angle and viscosity. Phase behavior study was also performed. The dual function characteristics of a zwitterionic surfactant were investigated by determining an isoelectric point, which was attained using zeta potential measurements and QCM (quartz crystal microbalance) experiments. The isoelectric point of DE7-OSA82-AO surfactant determined by the zeta potential measurement and QCM experiment was about 7.2 and 7.4, respectively. On the other hand, the isoelectric point of DEP52-OSA82-AOQ82 surfactant determined by the zeta potential measurement and QCM experiment was about 10.9 and 11.0, respectively. The frictional property measured using an automated mildness tester showed that DE7-OSA82-AO surfactant can provide a good softening effect at an acidic or neutral condition. On the other hand, DEP52-OSA82-AOQ82 was found to provide a good softening effect to a fabric surface at a pH below its isoelectric point of 11.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.83-87
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• 1998

To reduce the supersonic jet noise from the liquid rocket engine, water injetion silencers were designed and tested. Test variables were the mass flow rate of water jet, the length of primary pipe and the diameter of expansion pipe. Followings are the results of this study. 1. From the same mass flow rate of water, longer primary pipe was more effective to reduce the noise. 2. Noise level was significantly reduced with increasingly water flow rate. 3. The optimum water flow rate was 10～12 times of the propellant flow rate. 4. By installing expansion pipe, noise level was reduced approximately 30㏈ compared to without expansion pipe

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.310-318
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• 2016

This study deals with a method to localize a noise source occuring in a marine vehicle in a 3D environment. Even when access to the noise source is limited for a marine vehicle, such as a ship or a submarine in operation, the signal received on a hydrophone located elsewhere contains Doppler effected noise by moving relatively. This study suggests noise localization algorithm in 3D based on Doppler effect by moving marine vehicle. Using a known source mounted on the vehicle, the noise source was estimated by reducing the range of Doppler center and closest point of approach via the least square method. The algorithm was verified through various simulations and it was shown that the noise could be localized in 3D based on Doppler effect by employing two fixed hydrophones located at the vehicle's exterior points and a known reference signal generator located somewhere on the vehicle.

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.244-254
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• 2018

The first geophysical technique applied to the agricultural sector in Korea was electrical resistivity sounding and conducted in purpose of groundwater exploitation in the 1970s. According to the diversity of agricultural activities since the 1990s, various geophysical methods including electrical resistivity, electromagnetic induction, and self-potential method were applied to several agricultural fields such as soil characterization with saline concentration in vast reclaimed area, delineation of seawater intrusion regions in costal aquifer, safety inspection of embankment dikes with leakage problem, detection of ground subsidence from overpumping and tracing of groundwater aquifer contamination by leachate from livestock mortality burial or waste burial site. This paper introduces representative geophysical techniques that have been utilized in various agricultural fields and suggests several ways to develop the geophysical methods required for the precision agriculture field in the near future based on the past achievements.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.1076-1084
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• 2017

For analyzing the qualitative and quantitative analysis of fuel marker in petroleum products, the applicability of HPLC was studied. For the qualitative analysis of fuel marker in kerosene and automotive diesel, optimal analytical conditions(ratio of mobile phase solvent, flow rate, etc) in HPLC were selected and calibration curve for quantitative analysis of fuel marker was prepared based on the result of qualitative analysis. In particular, the correlation coefficient of calibration curve in kerosene and automotive diesel was shown to be 0.999 in a certain concentration range and it could be applied to the quantitative analysis. The results of analysis using the UV/Vis spectrometer, which is the current analysis method of fuel marker, were compared with the analysis results using the HPLC. The kerosene showed a low deviation of about 7 % and the automotive diesel showed a somewhat large deviation of about 20 %.

• Journal of the Korean Solar Energy Society
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• v.35 no.4
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• pp.1-7
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• 2015

The operation of the natural circulation type solar heating systems with facade integrated collector was analyzed by experiment. Two different types of flat plate solar collectors were used for these experiments. One was for the normal flat plate solar collector with the size of 1m*2m and the other was for the large size solar collector with $4m^2$(1m*4m). The experiments were carried out to investigate the effect of the series or parallel connection method on the performance of the collectors. As a result, the solar thermal system which is installed on the wall or facade would be applicable for the natural circulation type if the system design reflects various parameters, including collector connecting method(series or parallel), to provide enough vertical height between collector and storage tank, and to reduce pressure loss due to collector and piping network, etc. The natural circulation type of solar thermal system as proposed in this study can increase the system reliability by removing or minimizing the use of the components such as pump, controller, sensors which may cause serious troubles of the system for a long-time operation

• Applied Microscopy
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• v.29 no.2
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• pp.211-221
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• 1999

The ultrastructural changes of cuticular surface, excretory and digestive organs of Anisakis simplex larvae chronologically recovered from experimental cats were observed with a SEM and TEM. The larva recovered from an experimental cat at 3 days post-infection (PI) retained the cuticular surface with regular transverse striations and a longitudinal groove on the lateral side of body. This finding suggests that the molting of the 3rd stage larva of A. simplex to 4th one occurred from the 3rd day after infection in cats. The excretory organ (renette cell) consisted of a large cell with numerous ductules ramified from the main duct, mitochondria and secretory granules in cytoplasm. Secretory granules in the renette cell of larvae recovered at 24 hours PI were round whereas those of control and larvae recovered at 6 hours PI were amorphous. Muscular esophagus and ventriculus also retained many secretory granules in the cytoplasm. The secretory granules in these organs of larvae recovered at $6\sim24$ hours PI were electron-dense and widely distributed whereas those of control worm were packed in a pocket and retained various electron densities. In the cytoplasm of intestinal epithelial cells, numerous fine glycogen particles and mitochondria were distributed. The chronological changes of secretory granules in renette cell, muscular esophagus and ventriculus seem to be related with the worm penetration into host tissue.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.3
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• pp.259-264
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• 1999

A field experiment was carried out to determine the optimum application level of dicamba herbicide for efficient control of Calystegia japonica in silage corn field. Six treatments of application levels (0 ; control, $0.75{\ell},\;1.0{\ell},\;1.25{\ell},\;1.5{\ell},\;and\;2.0{\ell}/ha$) were arranged at National Livestock Research Institute, RDA, Suwon in 1995. The hybrid silage corn was DK 729, and dicamba herbicide was applied at 5~6 leaf stage of corn. The growth of corn was poor in control plot, and the days for tasseling and silking were delayed 1~4 days when compared with the plots of herbicide application. The control efficiency of Calystegia japonica was excellent as 74.3~94.6% in the plots of dicamba application. A slight injury of herbicide was observed at early stage of corn when applied at $1.25{\ell}$ and $1.5{\ell}$ of dicamba per ha, and severe injury was found at $2.0{\ell}$ of dicamba. Forage dry matter(DM) yield, and length of ear in the plots of dicamba treatments were significantly higher than those of control. The DM yield of control(4,866kg/ha) was only about 30% of dicamba treatment plot (14,960~16,340kg/ha). However, there was no yield difference among dicamba application level. The percentage of ear to total DM yield was ranged from 33.6 to 39.4%. With application of herbicide, the contents of crude protein and nitrogen free extract were increased, and that of crude fiber was decreased in stover. However, nutritive value of corn ear was very similar among all treatments, regardless of herbicide treatment. From the above results, it is recommended that optimum application level of dicamba herbicide was $0.75{\sim}1.0{\ell}/ha$ for efficient control of Calystegia japonica and for silage corn production without herbicide injury.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.4
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• pp.649-658
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• 2013

This study aims to discover the relations between physical activities and metabolic syndrome in postmenopausal women, in order to present basic data for health promotion of patients with metabolic syndrome. Based on Year 2 data of the 4th Korean National Health Nutrition Examination Survey, this study discovered that the prevalence rate of metabolic syndrome of the Korean women at the menopause was significantly higher as they got older and they had less physical activities. To keep their health and prevent from metabolic syndrome, it is suggested that further research is needed to develop physical activity programs for which preferences of patients and their restrictions are considered and verify the effects.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.696-700
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• 2003

$H_2SO_4$ and citric acid had higher extraction efficiency of $^{137}Cs$ from soil than the other chemicals. Thus, $H_2SO_4$and citric acid were used as additives on remediation experiment by electrokinetic method to increase removal efficiency of $^{137}Cs$ from the radioactive soil being stored during a long time. An average velocity of effluent discharged from experimental column $2.0{\times}10^{-2}$/cm/min and a volume of the discharged soil wastewater for 10 days is 3.6 Pore Volume. The 54% of a total of $^{137}Cs$ in the column was decontaminated for 10 days. Furthermore, the predicted values of residual concentration by the developed model were quite similar to those obtained from experiments.