• KIPS Transactions on Software and Data Engineering
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• v.8 no.6
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• pp.243-250
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• 2019

Because of a moving UAV has a lot of potential/kinetic energy, if the UAV falls to the ground, it may have a lot of impact. Because this can lead to human casualities, in this paper, the population density area on the UAV flight path is defined as a dangerous area. The conventional UAV path flight was a passive form in which a UAV moved in accordance with a path preset by a user before the flight. Some UAVs include safety features such as a obstacle avoidance system during flight. Still, it is difficult to respond to changes in the real-time flight environment. Using public Big Data for UAV path flight can improve response to real-time flight environment changes by enabling detection of dangerous areas and avoidance of the areas. Therefore, in this paper, we propose a method to detect and avoid dangerous areas for UAVs by utilizing the Big Data collected in real-time. If the routh is designated according to the destination by the proposed method, the dangerous area is determined in real-time and the flight is made to the optimal bypass path. In further research, we will study ways to increase the quality satisfaction of the images acquired by flying under the avoidance flight plan.

• Journal of Soil and Groundwater Environment
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• v.24 no.3
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• pp.24-35
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• 2019

It is known that ${\delta}^{13}C_{DIC}$ (carbon-13 isotope of dissolved inorganic carbonate (DIC) ions) of water increases when dissolved $CO_2$ degases. However, ${\delta}^{13}C_{DIC}$ could decrease when the pH of water is lower than 5.5 at the early stage of degassing. Laboratory experiments were performed to observe the changes of ${\delta}^{13}C_{DIC}$ as $CO_2$ degassed from three different artificial $CO_2$-rich waters (ACWs) in which the initial pH was 4.9, 5.4, and 6.4, respectively. The pH, alkalinity and ${\delta}^{13}C_{DIC}$ were measured until 240 hours after degassing began and those data were compared with kinetic isotope fractionation calculations. Furthermore, same experiment was conducted with the natural $CO_2$-rich water (pH 4.9) from Daepyeong, Sejong City. As a result of experiments, we could observe the decrease of DIC and increase of pH as the degassing progressed. ACW with an initial pH of 6.4, ${\delta}^{13}C_{DIC}$ kept increasing but, in cases where the initial pH was lower than 5.5, ${\delta}^{13}C_{DIC}$ decreased until 6 hours. After 6 hours ${\delta}^{13}C_{DIC}$ increased within all cases because the $CO_2$ degassing caused pH increase and subsequently the ratio of $HCO_3{^-}$ in solution. In the early stage of $CO_2$ degassing, the laboratory measurements were well matched with the calculations, but after about 48 hours, the experiment results were deviated from the calculations, probably due to the equilibrium interaction with the atmosphere and precipitation of carbonates. The result of this study may be not applicable to all natural environments because the pressure and $CO_2$ concentration in headspace of reaction vessels was not maintained constant as well as the temperature. Nevertheless, this study provides fundamental knowledge on the ${\delta}^{13}C_{DIC}$ evolution during $CO_2$ degassing, and therefore it can be utilized in the studies about carbonated water with low pH and the monitoring of geologic carbon sequestration.

• Clean Technology
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• v.24 no.4
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• pp.307-314
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• 2018

In this study, NMO (Natural Manganese Ore), $MnO_2$, and $Mn_2O_3$ catalysts were used in the selective catalytic reduction process to remove nitrogen oxides (NOx) using $NH_3$ as a reducing agent at low temperatures in the presence of oxygen. In the case of the NMO (Natural Manganese Ore), it was confirmed that the conversion of nitrogen oxides in the stability test did not change even after 100 hours at 423 K. The Kinetics experiments were carried out within the range where heat and mass transfer were not factors. From a steady-state Kinetics study, it was found that the low-temperature SCR reaction was zero order with the respect to $NH_3$ and 0.41 ~ 0.57 order with the respect to NO and 0.13 ~ 0.26 order with the respect to $O_2$. As temperature increases, the reaction order decreases as a result of $NH_3$ and oxygen concentration. It was confirmed that the reaction between the $NH_3$ dissociated and adsorbedon the catalyst surface and the gaseous nitrogen monoxide (E-R model) and the reaction with the adsorbed nitrogen monoxide (L-H model) occur.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.930-938
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• 2018

Underwater noise radiated from submarines is directly related to the probability of being detected by the sonar of an enemy vessel. Therefore, minimizing the noise of a submarine is essential for improving survival outcomes. For modern submarines, as the speed and size of a submarine increase and noise reduction technology is developed, interest in flow noise around the hull has been increasing. In this study, a noise analysis technique was developed to predict flow noise generated around a submarine shape considering the free surface effect. When a submarine is operated near a free surface, turbulence-induced noise due to the turbulence of the flow and bubble noise from breaking waves arise. First, to analyze the flow around a submarine, VOF-based incompressible two-phase flow analysis was performed to derive flow field data and the shape of the free surface around the submarine. Turbulence-induced noise was analyzed by applying permeable FW-H, which is an acoustic analogy technique. Bubble noise was derived through a noise model for breaking waves based on the turbulent kinetic energy distribution results obtained from the CFD results. The analysis method developed was verified by comparison with experimental results for a submarine model measured in a Large Cavitation Tunnel (LCT).

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.365-370
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• 2019

In this study, effects of the ultrasonic irradiation during the reaction process were investigated for the enantioselective kinetic resolution (EKR) reaction of racemic epoxides in the presence of chiral cobalt salen catalysts, as compared to that of using the conventional mechanical stirring. In order to compare catalytic activities, the chiral cobalt salen complexes having $AlCl_3-$, $BF_3-$ and nitrobenzenesulfonic acid (NBSA) were synthesized and used as catalysts, and then three kinds of the racemic epoxides such as ephichlorohydrine (ECH), epoxy phenoxypropane (EPP) and propylene oxide (PO) were used as reactants. In addition, EKR reactions have been performed using the water and methanol as nucleophiles, respectively. The unique contribution of ultrasonic irradiation as a powerful mixing medium was evaluated in this study to improve the kinetics in comparison to the conventional mechanical agitation during EKR reactions. The reaction time to obtain the highest 99 ee% became shorten more than that of above 60%, when the ultrasonic irradiation was used. This result may be interpreted by the cavitation effect of ultrasound in the solution, generating a powerful shear force for the very violent mixing.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.2
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• pp.103-108
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• 2019

Non-equilibrium molecular dynamics simulation on the thermal boundary resistance(TBR) of an aluminum(Al)/silicon(Si) interface was performed in the present study. The constant heat flux across the Si/Al interface was simulated by adding the kinetic energy in hot Si region and removing the same amount of the energy from the cold Al region. The TBR estimated from the sharp temperature drop at the interface was independent of heat flux and equal to $5.13{\pm}0.17K{\cdot}m^2/GW$ at 300K. The simulation result was experimentally confirmed by the time-domain thermoreflectance technique. A 90nm thick Al film was deposited on a Si(100) wafer using an e-beam evaporator and the TBR on the film/substrate interface was measured using the time-domain thermoreflectance technique based on a femtosecond laser system. A numerical solution of the transient heat conduction equation was obtained using the finite difference method to estimate the TBR value. Experimental results were compared to the prediction and discussions on the nanoscale thermal transport phenomena were made.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.547-555
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• 2018

In addition to North America and Europe, Korea is also responding to the toxic damage caused by the production and distribution of chemicals. Methods for assessing bio-toxicity of harmful substances have been widely introduced, but it is required of quantitative and speedy information for modeling. For 6 heavy metals, as zinc, copper, chrome, cadmium, mercury and lead, bio-toxicity assessment and kinetics model were constructed using Vibrio fischeri which is widely used luminous bacteria. The degree of luminescence activity and the toxicity of heavy metals were relative limunescence unit, RLU measured as by using a photomultiplier embedded device. The toxicity was assessed by the concentration levels giving under 20% lethality and lethal concentration, $EC_{50}$. In the results, the toxicity order were followed from mercury, lead, copper, chrome, zinc and cadmium. $EC_{{50},{\infty}}$ obtained by trends of $EC_{50}$ by time follows had highly linear agreement with main parameters of bio-toxicity modelling. The average error rates of the reproduced lethality obtained from DAM and TDM model on the basis of body residue, were 10.2% for mercury, lead, copper, chrome and 20.0 for the all 6 methals.

• Journal of Korean Medical Ki-Gong Academy
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• v.20 no.1
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• pp.118-147
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• 2020

Objective : The purpose of this study is to understand trends of pelvic correction therapy in Korea and to assist research activities on pelvic correction therapy. Also, this study selected and presented indicators for measuring pelvic slope to help ensure consistent studies with uniform indicators in future studies related to pelvic correction. Methods : The following keywords "골반", "골반 교정", "골반 변위" "Pelvic correction" were searched on three specialized search sites (RISS, NAI, DBpia). Trends in pelvic correction therapy were analyzed through the selected researches suitable among these searched researches in an overview format. Results : 1. A total of 7,806 studies were searched and a total of 268 studies were finally selected. 2. Studies began in 1977 and have been actively studied until recently, with 35 studies in 2017 being the most recent trend since 2000. 3. In the results according to the Main Field of Research, the 'Arts and Kinesiology'(113, 42.16%) and 'Medicine and Pharmacy'(103, 38.43%) were the most in order. To the Middle Field, the 'Kinesiology was the largest with 96(35.82%) studies. 4. In the results according to the study design, 'Pre-Post Test(PPT)' was the largest with 107 studies. 5. In the results according to the Intervention, 'Exercise' was the largest with 165 studies, of which 'Pilates' and 'Yoga' in 'Training' was the largest. 6. Among the evaluation method, the 'Pelvic Index' was used 146 times, followed by 'Spinal Alignment (99)', 'Other Joints (93)', and 'Kinetic Specialized Measurement Test (56)'. 7. Among the evaluation methods, the pelvic slope measurement indicators were PT (58), PH (48), Pelvic Torsion (40), Iliac Crest (38), ASIS-PSIS distance/angle (27), and Pelvic Width (I.W., I.L., S.W) (25) in order. 8. The journals that published the most researches were KJSS(Korean Alliance For Health, Physical Education, Recreation, And Dance;9), and JKPT(Korean Physical Therapy;9). Among the University, the Graduate School of Silla University published the most papers (12). 9. The author who published the most studies were Seungjin Park(3), the co-authors were Hoseong Lee, Gideok Park, Seongsu Bae(3), and the Thesis-Director Gyeongok Lee(7). Conclusions : 1. Studies on pelvic correction treatment continue to increase every year. 2. The main academic field of pelvic correction is 'Sports', 'Physical Therapy', and 'Medical Science'. 3. The most chosen research design method in the study on pelvic correction treatment was 'Pre-Post Test(PPT)', primarily as an intermediary, Pilates and yoga during exercise therapy, and then Chiropractic during handcraft were used as multiple frequencies. 4. Among the various measurement method indicators of pelvic correction previously used, multiple frequency was taken up in the order of PT, PH, Pelvic Torsion, iliac crest, ASIS-PSIS distance/angle, and pelvic width (I.W.,I.L.,S.W). Typically, measurements through "ASIS-PSIS angle" are recommended and are considered as the most rational in clinical trials.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.312-318
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• 2011

We have investigated the kinetics and catalytic activity of $CO_2$-lignite gasification with various metal precursors as catalysts. $K_2CO_3$, $Mn(NO_3)_2$, and $Ce(NO_3)_3$ were used and impregnated on a coal using an evaporator. The gasification experiments were carried out with the low rank coal loaded with 5 wt% catalyst at the temperature range from $700{\sim}900^{\circ}C$ and atmospheric pressure with the $N_2-CO_2$ reactant gas mixture. The catalytic effect on the gasification rate of the low rank coal with $CO_2$ was determined by the thermogravimetric analyzer. It was observed that the low rank coal reached the complete carbon conversion regardless of the kinds of catalysts at $900^{\circ}C$ from the results of TGA. The catalytic activity was ranked as 5 wt% $K_2CO_3$ > 5 wt% $Mn(NO_3)_2$ > 5 wt% $Ce(NO_3)_3$ > Non-catalyst at $900^{\circ}C$. The gasification rate increased with increasing the temperature. The activation energy of the catalytic gasification with 5 wt% $K_2CO_3$ was 119.0 kJ/mol, which was the lowest among all catalysts.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.167-173
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• 2011

Nickel cobalt ferrite($Ni_{0.5}Co_{0.5}Fe_2O_4$) powder was prepared through the ceramic route by the calcination of a stoichiometric mixture of NiO, CoO and $Fe_2O_3$ at $1100^{\circ}C$. The pressed pellets of $Ni_{0.5}Co_{0.5}Fe_2O_4$ were isothermally reduced in pure hydrogen at $800{\sim}1100^{\circ}C$. Based on the thermogravimetric analysis, the reduction behavior and the kinetic reaction mechanisms of the synthesized ferrite were studied. The initial ferrite powder and the various reduction products were characterized by X-ray diffraction, scanning electron microscopy, reflected light microscope and vibrating sample magnetometer to reveal the effect of hydrogen reduction on the composition, microstructure and magnetic properties of the produced Fe-Ni-Co alloy. The arrhenius equation with the approved mathematical formulations for the gas solid reaction was applied to calculate the activation energy($E_a$) and detect the controlling reaction mechanisms. In the initial stage of hydrogen reduction, the reduction rate was controlled by the gas diffusion and the interfacial chemical reaction. However, in later stages, the rate was controlled by the interfacial chemical reaction. The nature of the hydrogen reduction and the magnetic property changes for nickel cobalt ferrite were compared with the previous result for nickel ferrite. The microstructural development of the synthesized Fe-Ni-Co alloy with an increase in the reduction temperature improved its soft magnetic properties by increasing the saturation magnetization($M_s$) and by decreasing the coercivity($H_c$). The Fe-Ni-Co alloy showed higher saturation magnetization compared to Fe-Ni alloy.