• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.8-15
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• 2021

TiO2 has been used in various fields such as solar cells, dental implants, and photocatalysis, because it has high physical and chemical stability and is harmless to the body. TiO2 nanofibers which have a large specific surface area also show a good reactivity in bio-friendly products and excellent photocatalysis in air and water purification. To fabricate TiO2 nanofibers, an electrospinning method was used. To observe the diameter of TiO2 nanofibers with fabrication variables, the fabrication variables was divided into precursor composition variables and process variables and microstructure was analyzed. The concentrations of PVP (Polyvinylpyrrolidone) and TTIP (Titanium(IV) isopropoxide) were selected as precursor composition variables, and inflow velocity and voltage were also selected as process variables. Microstructure and crystal structure of TiO2 nanofibers were analyzed using FE-SEM (Field emission scanning electron microscope) and XRD (X-ray diffraction), respectively. As-spun TiO2 nanofibers with an average diameter of about 0.27 ㎛ to 1.31 ㎛ were transformed to anatase TiO2 nanofibers with an average diameter of about 0.22 ㎛ to 0.78 ㎛ after heat treatment of 3 hours at 450℃. Anatase TiO2 nanofibers with an average diameter of 0.22 ㎛ can be expected to improve the photocatalytic properties by increasing the specific surface area. To change the average diameter of TiO2 nanofibers, the control of precursor composition variables such as concentrations of PVP and TTIP is more efficient than the control of electrospinning process variables such as inflow velocity and voltage.

• Clean Technology
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• v.28 no.1
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• pp.79-93
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• 2022

In this study, an electronics industrial wastewater activated sludge model (e-ASM) to be used as a Water Digital Twin was calibrated based on real high-tech electronics industrial wastewater treatment measurements from lab-scale and pilot-scale reactors, and examined for its treatment performance, effluent quality prediction, and optimal process selection. For specialized modeling of a high-tech electronics industrial wastewater treatment system, the kinetic parameters of the e-ASM were identified by a sensitivity analysis and calibrated by the multiple response surface method (MRS). The calibrated e-ASM showed a high compatibility of more than 90% with the experimental data from the lab-scale and pilot-scale processes. Four electronics industrial wastewater treatment processes-MLE, A2/O, 4-stage MLE-MBR, and Bardenpo-MBR-were implemented with the proposed Water Digital Twin to compare their removal efficiencies according to various electronics industrial wastewater characteristics. Bardenpo-MBR stably removed more than 90% of the chemical oxygen demand (COD) and showed the highest nitrogen removal efficiency. Furthermore, a high concentration of 1,800 mg L^-1 T MAH influent could be 98% removed when the HRT of the Bardenpho-MBR process was more than 3 days. Hence, it is expected that the e-ASM in this study can be used as a Water Digital Twin platform with high compatibility in a variety of situations, including plant optimization, Water AI, and the selection of best available technology (BAT) for a sustainable high-tech electronics industry.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.313-331
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• 2022

Natural or native abiotic molecular hydrogen (H₂) is a major component in natural gas, however yet its importance in the global energy sector's usage as clean and renewable energy is underestimated. Here we review the occurrence and geological settings of native hydrogen to demonstrate the much widesprease H₂ occurrence in nature by comparison with previous estimations. Three main types of source rocks have been identified: (1) ultramafic rocks; (2) cratons comprising iron (Fe²⁺)-rich rocks; and (3) uranium-rich rocks. The rocks are closely associated with Precambrian crystalline basement and serpentinized ultramafic rocks from ophiolite and peridotite either at mid-ocean ridges or within continental margin(Zgonnik, 2020). Inorganic geological processes producing H₂ in the source rocks include (a) the reduction of water during the oxidation of Fe²⁺ in minerals (e.g., olivine), (b) water splitting due to radioactive decay, (c) degassing of magma at low pressure, and (d) the reaction of water with surface radicals during mechanical breaking (e.g., fault) of silicate rocks. Native hydrogen are found as a free gas (51%), fluid inclusions in various rock types (29%), and dissolved gas in underground water (20%) (Zgonnik, 2020). Although research on H₂ has not yet been carried out in Korea, the potential H₂ reservoirs in the Gyeongsang Basin are highly probable based on geological and geochemical characteristics including occurrence of ultramafic rocks, inter-bedded basaltic layers and iron-copper deposits within thick sedimentary basin and igneous activities at an active continental margin during the Permian-Paleogene. The native hydrogen is expected to be clean and renewable energy source in the near future. Therefore it is clear that the origin and exploration of the native hydrogen, not yet been revealed by an integrated studies of rock-fluid interaction studies, are a field of special interest, regardless of the presence of economic native hydrogen reservoirs in Korea.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.111-120
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• 2023

The nucleation mechanism was studied using a calcium ion selective electrode (Ca ISE) to observe the formation of CaCO₃, a representative mineral in the CO2 cycle, and to analyze the effect of the Mg/Ca-ratio and temperature on the formation of pre-nucleation cluster (PNC) and CaCO₃. As a result of the experiment, a small amount of crystal was formed. Energy dispersive X-ray spectroscopy (EDS) was used for surface element analysis, and a field emission scanning-electron microscope (FE-SEM) was used for the morphology analysis of synthesized carbonates. These results showed that various shapes of crystalline CaCO₃ (calcite, aragonite, etc.) were observed for each Mg/Ca ratio and temperature. In addition, the calibration plot obtained from Ca ISE showed information on the formation process of CaCO₃. Our results showed that as magnesium ions interfered with the binding of calcium and carbonate ions and delayed the aggregation between PNCs, the nucleation and formation of CaCO₃ were delayed. On the other hand, the temperature showed an opposite trend as compared to the effect of magnesium under our experimental conditions, indicating that temperature accelerated the formation of CaCO₃. Furthermore, the morphology of CaCO₃ clearly changed according to the Mg/Ca ratio and temperature, and it was confirmed that the two factors are very important for CaCO₃ formation in that they could affect the overall process.

• Journal of Korea Entertainment Industry Association
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• v.13 no.8
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• pp.313-323
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• 2019

For the actors on video, facial expression acting can easily become 'forced facial expression' or 'over-acting'. Also, if self-restraint is emphasized too much, then it becomes 'flat acting' with insufficient emotions. By bringing forth questions in regard to such facial expression acting methods, this study analyzed the facial expression acting of the actors in genre dramas with strong commercial aspects. In conclusion, the facial expression acting methods of the actors in genre dramas were being conducted in a typical way. This means that in visual conventions of video acting, the aesthetic standard has become the important standard in the facial expression acting of the actors. In genre dramas, the emotions of the characters are often revealed in close-up shots. Within the close-up shot, the most important expressive medium in a 'zoomed-in face' is the 'pupil of the eye', and emotions are mostly expressed through the movements of the eye and muscles around it. The second most important expressive medium is the 'mouth'. The differences in the degree of opening and closing the mouth convey diverse emotions along with the expression of the 'eye'. In addition, tensions in the facial muscles greatly hinder the expression of emotions, and the movement of facial muscles must be minimized to prevent excessive wrinkles from forming on the surface of the face. Facial expressions are not completed just with the movement of the muscles. Ultimately, the movement of the muscle is the result of emotions. Facial expression acting takes place after having emotional feelings. For this, the actor needs to go through the process of 'personalization' of a character, such as 'emotional memory', 'concentration' and 'relaxation' which are psychological acting techniques of Stanislavsky. Also, the characteristics of close-up shots that visually reveal the 'inner world' should be recognized. In addition, it was discovered that the facial expression acting is the reaction acting that provides the important point in the unfolding of narratives, and that the method of facial expression and the size of the shots required for the actors are different depending on the roles of main and supporting characters.

• Journal of Food Hygiene and Safety
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• v.38 no.6
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• pp.449-456
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• 2023

In this study, we developed Rapid Enrichment Broth for Vibrio parahaemolyticus (REB-V), a broth capable enriching V. parahaemolyticus from 10⁰ CFU/mL to 10⁶ CFU/mL within 6 hours, which greatly facilitates the rapid detection of V. parahaemolyticus. Using a modified Gompertz model and response surface methodology, we optimized supplement sources to rapidly enrich V. parahaemolyticus. The addition of 0.003 g/10 mL of D-(+)-mannose, 0.002 g/10 mL of L-valine, and 0.002 g/10 mL of magnesium sulfate to 2% (w/v) NaCl BPW was the most effective combination of V. parahaemolyticus enrichment. Optimal V. parahaemolyticus culture conditions using REB-V were at pH 7.84 and 37℃. To confirm REB-V culture efficiency compared to 2% (w/v) NaCl BPW, we assessed the amount of enrichment achieved in 7 hours in each medium and extracted DNA samples from each culture every hour. Real-time PCR was performed using the extracted DNA to verify the applicability of this REB-V culture method to molecular diagnosis. V. parahaemolyticus was enriched to 5.452±0.151 Log CFU/mL in 2% (w/v) NaCl BPW in 7 hours, while in REB-V, it reached 7.831±0.323 Log CFU/mL. This confirmed that REB-V enriched V. parahaemolyticus to more than 10⁶ CFU/mL within 6 hours. The enrichment rate of REB-V was faster than that of 2% (w/v) NaCl BPW, and the amount of enrichment within the same time was greater than that of 2% (w/v) NaCl BPW, indicating that REB-V exhibits excellent enrichment efficiency.

• Food Science and Preservation
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• v.30 no.5
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• pp.857-867
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• 2023

In this study, the extraction yield, acidic polysaccharides and ginsenosides of red and black ginseng were optimized by using the response surface methodology in consideration of the ethanol concentration and temperature of the extraction. The R² of the model formula for the yield, acidic polysaccharides and ginsenosides was 0.8378-0.9679 (p<0.1). An optimal extraction yield of 5.29% was reached for red ginseng soluble solids when 1.52% ethanol concentration was used at a temperature of 67.27℃. Additionally, the optimal extraction yield for black ginseng soluble solid was 6.11% when 3.12% ethanol concentration was used at a temperature of 66.13℃. Furthermore, the optimal conditions for extracting acidic polysaccharides from red ginseng were using an ethanol concentration of 4.03% at a temperature of 69.61℃; a yield of 1.86 mg/mL was obtained. The optimal extraction yield for acidic polysaccharides from black ginseng was 1.80 mg/mL when extracted using a concentration of 24.67% of ethanol at a temperature of 71.14℃. An optimal extraction yield of 0.22 mg/mL was reached for ginsenoside Rg₁ from red ginseng when 79.92% ethanol concentration was used at a temperature of 70.62℃. The optimal extraction yield of ginsenoside Rg₃ from black ginseng was 0.31 mg/mL when ethanol was used at a concentration of 75.70% at a temperature of 65.49℃. The ideal extraction conditions for obtaining the maximum yield of both acidic polysaccharide and ginsenoside from red and black ginseng were using ethanol at a concentration between 35 and 50% at an extraction temperature of 70℃.

• Information Systems Review
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• v.19 no.2
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• pp.1-19
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• 2017

Original scripts of e-learning lectures for the CEOs of corporation S were analyzed using topic analysis, which is a text mining method. Twenty-two topics were extracted based on the keywords chosen from five-year records that ranged from 2011 to 2015. Research analysis was then conducted on various issues. Promising topics were selected through evaluation and element analysis of the members of each topic. In management and economics, members demonstrated high satisfaction and interest toward topics in marketing strategy, human resource management, and communication. Philosophy, history of war, and history demonstrated high interest and satisfaction in the field of humanities, whereas mind health showed high interest and satisfaction in the field of in lifestyle. Studies were also conducted to identify topics on the proportion of content, but these studies failed to increase member satisfaction. In the field of IT, educational content responds sensitively to change of the times, but it may not increase the interest and satisfaction of members. The present study found that content production for CEOs should draw out deep implications for value innovation through technology application instead of simply ending the technical aspect of information delivery. Previous studies classified contents superficially based on the name of content program when analyzing the status of content operation. However, text mining can derive deep content and subject classification based on the contents of unstructured data script. This approach can examine current shortages and necessary fields if the service contents of the themes are displayed by year. This study was based on data obtained from influential e-learning companies in Korea. Obtaining practical results was difficult because data were not acquired from portal sites or social networking service. The content of e-learning trends of CEOs were analyzed. Data analysis was also conducted on the intellectual interests of CEOs in each field.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.13-26
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• 1968

To establish the most efficient method of nitrogen and phosphorus fertilization in paddy rice a series of internationally coordinated research using $N^{15}\;P^{32}$ isotopes were carried out from the year 1962 through 1967, supervised by the Joint FAO/IAEA Division of Atomic Energy in Agriculture under the auspicies of FAO, UN. In Korea College of Agriculture, Seoul National University had been participated in the Coordinated Research Programme from the year 1963 through the last year, arid the results obtained through the six years' researches are summarized as follows: 1. In the application of superphosphate broadcasting or placement at the surface of paddy as basal dressing was most efficient. 2. Split or late application of superphosphate did not affect the grain yield of the rice, but its efficiency in the rice plant uptake was less than in the case of basal dressing of whole amounts. 3. The contents of available soil phoshorus of the experimental sites in Korea were above 60 ppm, and the efficiency of phosphorus utilization of the rice from the fertilizer was approximately 10 per cent. The grain yield response of the rice to phosphorus application in Korea was rather small comparing to those of other countries. 4. The nitrogen uptake of the rice plants from the fertilizer was most efficient when the fertilizer was applied at the time of ear prime growth. However, the most efficient utilization of nitrogen did not necessarily accompany the maximum yield of the rice and basic application of adequate amount of nitrogen was required to secure proper number of panicles. 5. In the application of nitrogenous fertilizer shallow placement at 5 cm depth was most efficient. The effect of split application of nitrogen was not so noticeable. It seemed due to the fact that total application amount of nitrogen, 60 kg N/ha, was smaller than that of usual dosage in Korea. 6. The efficiency of nitrogen utilization of the rice from the fertilizer was about 40 percent in Korea, and the yield reponse of the rice plant to nitrogen application was remarkable comparing to those of other countries, showing the marked differences in the fertilizer efficiency and grain yield according to the application method. 7. The nitrogen uptake of the rice plant was not likely affected by the time and the rate of phosphorus application whereas the efficiency of phosphorus utilization was affected to some degree by the method of nitrogen application.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.35-52
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• 1973

Red Yellow Soils occur very commonly in Korea and constitute the important upland soils of the country which are either presently being cultivated or are suitable for reclaiming and cultivating. These soils are distributed on rolling, moutain foot slopes, and terraces in the southern and western parts of the central districts of Korea, and are derived from granite, granite gneiss, old alluvium and locally from limestone and shale. This report is a summary of the morphology, physical and chemical characteristics of Red Yellow Soils. The data obtained from detailed soil surveys since 1964 are summarized as follows. 1. Red-Yellows Soils have an A, Bt, C profile. The A horizon is dark colored coarse loamy or fine loamy with the thin layer of organic matter. The B horizon is dominantly strong brown, reddish brown or yellowish red, clayey or fine loamy with clay cutans on the soil peds. The C horizon varies with parent materials, and is coarser texture and has a less developed structure than the Bt horizon. Soil depth, varied with relief and parent materials, is predominantly around 100cm. 2. In the physical characteristics, the clay content of surface soil is 18 to 35 percent, and of subsoil is 30 to 90 percent nearly two times higher than the surface soil. Bulk density is 1.2 to 1.3 in the surface soil and 1.3 to 1.5 in the subsoil. The range of 3-phase is mostly narrow with 45 to 50 percent in solid phase, 30 to 45 percent in liquid one, and 5 to 25 percent in gaseous state in the surface soil; and 50 to 60 solid, 35 to 45 percent liquid and less than 15 percent gaseous in the subsoil. Available soil moisture capacity ranges from 10 to 23 percent in the surface soil, and 5 to 16 percent in the subsoil. 3. Chemically, soil reaction is neutral to alkaline in soils derived from limestone or old fluviomarine deposits, and acid to strong acid in other ones. The organic matter content of surface soil varying considerably with vegetation, erosion and cultivation, ranges from 1.0 to 5.0 percent. The cation exchange capacity is 5 to 40 me/100gr soil and closely related to the content of organic matter, clay and silt. Base saturation is low, on the whole, due to the leaching of extractable cations, but is high in soils derived from limestone with high content of lime and magnesium. 4. Most of these soils mainly contain halloysite (a part of kaolin minerals), vermiculite (weathered mica), and illite, including small amount of chlorite, gibbsite, hematite, quartz and feldspar. 5. Characteristically they are similar to Red Yellow Podzolic Soils and a part of Reddish Brown Lateritic Soils of the United States, and Red Yellow Soils of Japan. According to USDA 7th Approximation, they can be classified as Udu Its or Udalfs, and in FAO classification system to Acrisols, Luvisols, and Nitosols.