• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.27-34
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• 2008

The vertical distribution and origin of particulate organic matter (POM) were investigated in Shingu reservoir on 4th July (pre-monsoon) and 7th August (post-monsoon) 2006. High turbid water (120 NTU) were found at 4.5 m water depth in postmonsoon period. The average C/N ratio of POM was about 5.70 and 6.96 in surface water and bottom water, respectively in pre-monsoon period, exhibiting the close values to its ratio in phytoplankton cell. However, the average C/N ratio was 7.10 in surface water and 12.81 in bottom water in post-monsoon period. In addition, the ${\delta}^{13}C$ values of POM in pre-monsoon period ranged from -25.1%o to -26.1%o in whole water column, but the ${\delta}^{13}C$ values of POM in post-monsoon period showed relatively wide range between -23.2%o and -27.5%o. The apparently lighter values (average -27.5%o) in near bottom water (4.5 m water depth) demonstrate that POM in high turbid water in post-monsoon period may be derived from the outside terrestrial plants through heavy rainfall during the summer monsoon period. The present study suggests that carbon and nitrogen stable isotope ratios as well as C/N ratios should be useful indexes to clarify the origin of POM.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.292-299
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• 2012

We made 8 wt% silica dispersion system with fumed silica and photo curable acrylic monomer by beads mill process. These dispersions could be applied in organic/inorganic hybrid coating systems. These dispersions could be applied in organic/inorganic hybrid coating systems. The 4 species of photo curable acrylic monomer which was presence of hydroxyl group, different solubility parameter, and different molecular size were used in the silica dispersions. Stability of polar solvent, isopropyl alcohol, in silica dispersions was investigated. We investigated the stability of silica dispersions by using steady-state and dynamic rheology. As the monomer has hydroxyl group increased in mono and binary monomer silica dispersions, they showed non flocculated stable sol (loss modulus (G")> storage modulus (G')). When polar solvent IPA was added into slightly flocculated silica dispersions, they changed to non flocculated stable sol.

• Journal of Korea Entertainment Industry Association
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• v.14 no.2
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• pp.27-40
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• 2020

Recently, popular entertainers have contributed significantly to the achievement of TV program and exportation, which make them attract more attention. Therefore, this study investigates the relationship perception of broadcasting entertainers in inductive interview study. Thoughts of entertainers can affect theirs' behavior and attitude as well as value and thought, which makes it necessary on celebrity studies to examine entertainers' ideas. This study divides into drama and variety show for genres and cast portions are classified into three categories; leading, supporting, and minor role. We conducted an interview study on 48 entertainers in drama and variety entertainment programs and have explored data by using Nvivo 11 program. Entertainers' perception on their relationship in program can be sub-categorized into ideas on PDs, script writers, and colleague entertainers. Perception on PD revealed significant difference on consciousness on PDs' and script writers' authority, treatment, and communication. In addition, perception on colleague entertainers revealed significant result on colleague membership, relationship between seniors and newcomers, competition, and communication with colleagues. Because this study covered all relationship perceptions, and it is possible to come up with new practical implications, it is difficult to suggest diverse guidance for the harmonious awareness of entertainers. Therefore, future studies should be analyzed to address these limitations and provide more implications.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.17-30
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• 2009

Underground construction such as tunneling can induce damages on the surrounding rock mass, due to the stress concentration of in situ stresses and excessive energy input during construction sequence, such as blasting. The developed damage on the rock mass can have substantial influence on the mechanical and hydraulic behaviors of the rock masses around a tunnel. In this study, investigation on the generation of damage around an opening in a jointed rock model under biaxial compression condition was conducted. The joint dip angles employed are 30, 45, and 60 degrees to the horizontal, and the synthetic rock mass was made using early strength cement and water. From the biaxial compression test, initiation and propagation of tensile cracks at norm to the joint angle were found. The propagated tensile cracks eventually developed rock blocks, which were dislodged from the rock mass. Furthermore, the propagation process of the tensile cracks varies with joint angle: lower joint angle model shows more stable and progressive tensile crack propagation. The development of the tensile crack can be explained under the hypothesis that the rock segment encompassed by the joint set is subjected to the developing moment, which can be induced by the geometric irregularity around the opening in the rock model. The experiment results were simulated by using discrete element method PFC 2D. From the simulation, as has been observed from the test, a rock mass with lower joint angle produces wider damage region and rock block by tensile cracks. In addition, a rock model with lower joint angle shows progressive tensile cracks generation around the opening from the investigation of the interacted tensile cracks.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.1
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• pp.51-54
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• 2018

Purpose $^{18}F-THK5351$ is the newly developed PET probe for tau imaging in alzheimer's disease. The purpose of study was to establish the automated production of $^{18}F-THK5351$ on a commercial module. Materials and Methods Two different approaches were evaluated for the synthesis of $^{18}F-THK5351$. The first approach (method I) included the nucleophilic $^{18}F$-fluorination of the tosylate precursor, subsequently followed by pre-HPLC purification of crude reaction mixture with SPE cartridge. In the second approach (method II), the crude reaction mixture was directly introduced to a semi-preparative HPLC without SPE purification. The radiosynthesis of $^{18}F-THK5351$ was performed on a commercial GE $TRACERlab^{TM}$ $FX-_{FN}$ module. Quality control of $^{18}F-THK5351$ was carried out to meet the criteria guidelined in USP for PET radiopharmaceuticals. Results The overall radiochemical yield of method I was $23.8{\pm}1.9%$ (n=4) as the decay-corrected yield (end of synthesis, EOS) and the total synthesis time was $75{\pm}3min$. The radiochemical yield of method II was $31.9{\pm}6.7%$ (decay-corrected, n=10) and the total preparation time was $70{\pm}2min$. The radiochemical purity was>98%. Conclusion This study shows that method II provides higher radiochemical yield and shorter production time compared to the pre-SPE purification described in method I. The $^{18}F-THK5351$ synthesis by method II will be ideal for routine clinical application, considering short physical half-life of fluorine-18 ($t_{1/2}=110min$).

• Journal of the Korean Chemical Society
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• v.58 no.2
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• pp.179-185
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• 2014

Commercial (S)-naproxen was racemized under strong basic condition. After checking the peak position of (R)- and (S)-naproxen by analysis the recemized naproxen, optical purity of 19 commercialized naproxens sold in 2013 in Korea were examined by chiral HPLC. The Chiralcel OD-H column, ChiralHyun-LE(S)-1 column and LUX-Cellulose-1 column were used as chiral stationary phases and the mixed eluent of hexane:isopropanol:acetic acid as 100:1:0.1 was used as a mobile phase with a flow rate of 1.0 mL/min. Each data was obtained from an average value of at least three different experiments for each sample and the relative standard deviation of them appeared very small. The average optical purity values obtained from three different chiral columns were very similar and the total average optical purity value (99.32%) of nineteen commercialized naproxens used in this study were larger than those of three years ago (98.17%).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.721-728
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• 2016

97% of water on earth exists in the form of seawater. Therefore, the use of marine resources is one of the most important research issues at present. The use of seawater is expanding in various fields (seawater desalination, cooling water for nuclear power plants, deep seawater utilization, etc.). Seawater intake systems utilizing sand filters in order to take in clean seawater are being actively employed. For the intake pipe used in this system, assuring equal intake flows through the respective holes is very important to improve the efficiency of the intake and filtering process. In this study, we analyzed the efficiency of the dual structure perforated pipe used in the seawater intake system using 3D numerical simulations and the inflow rate according to the gap of the up holes. In the case of decreasing gaps in the up holes toward the pipe end, the variation of the total inflow rate was small in comparison with the other cases. However, the standard deviation of the inflow rate through the up holes was the lowest in this case. Also, stable flow occurred, which can improve the efficiency of the intake process. In the future, a sensitivity analysis of the various conditions should be performed based on the results of this study, in order to determine the factors influencing the efficiency, which can then be utilized to derive optimal designs suitable for specific environments.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.4
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• pp.274-281
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• 2015

Thermal and nuclear power plants on shore commonly use the sea water for cooling facility. Discharged cooling water has the high kinematic energy potential due to amount of water flux. Numerical analysis was made to find the suitable combinations between the arrangement of tidal turbines and the overall dimensions of the discharged channel. Several parameters such as the turbine diameter to inlet size, and the axial distance to turbine size were investigated. Power coefficients for various test conditions were also compared to see the effect of inlet configurations such as single inlet and dual inlet. For the single inlet, the mean power coefficient appeared to be gradually decreased with increasing distance, and the maximum power was obtained when the turbine diameter was same as the inlet diameter. For the dual inlet, the tendency was similar so that the better result when the turbine diameter was same as the inlet diameter. It is expected that the present methodology can be extensively utilized to harness the high kinetic energy flow of the discharge channel of power plant.

• Cartoon and Animation Studies
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• s.47
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• pp.273-294
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• 2017

Korea has suffered numerous casualties due to a lot of accidents caused by safety insufficiency in recent years. Therefore, safety education is more important than ever before, and 'how to educate with what contents' is an important subject. Especially, experience education is effective rather than theoretical education because of the nature of safety education. However, it is not easy to design and develop these safety education programs. There is not much opportunity to access first-aid training, which is a part of safety education, unless it is compulsory to learn through public institutions. As a result, program utilization on safety education in Korea is still insufficient to what it should be. With that taken into account, this study proposed an effective serious game with fun and immersion for medical first-aid education. To do this, we analyzed five medical games through 20 cases of first-aid applications and elicited five factors that enhance the usability of serious games. With an analysis of five medical games, we selected one game to borrow the game rules, and applied the elicited five elements in the forms of level-up structure, iterative learning, compensation outcomes, competition system, and information transfer. The proposed medical education functional games should have 1) a character that plays a role of a patient, 2) a narrative flow that shows the situation, 3) the user should judge the situation and induce first aid. 4) compensation, levels, and simple repetition should be designed, and 5) information should be shared with the others in the given community. The results of this study is believed to contribute to enhance the medical emergency education in Korea.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.373-381
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• 2016

In this study, we investigate the characteristics of the drag reduction of a circular cylinder having a detached splitter plate at the wake side. We measure the fluid force on a circular cylinder and visualize the field using particle image velocimetry (PIV) with a high Reynolds number, Re = 10,000. The experimental paraeters used were the width ratios (H/B = 0.5~1.5) of splitters to the prism width and the gap ratios (G/B = 0~2) between the prism and the splitter plate. The drag-reduction rate of the circular cylinder increased with H/B in the case of the same G/B, and it increased and then decreased with G/B in the case of the same H/B. The vortices of the opposite direction on the upper and lower sides of the detached splitter plate were generated by installing the plate. Reverse flow was caused by the vortices at the wake region of the circular cylinder, and the drag of the circular cylinder was decreased by the reverse flow.