• Bulletin of the Korean Chemical Society
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• v.14 no.5
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• pp.599-602
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• 1993

Micellization process of dodecyltrimethylammonium bromide (DTAB) was studied by using the aromatic probe (benzene) which dissolved in aqueous DTAB solutions. Proton NMR chemical shift measurements of DTAB and DTAB-benzene system showed that benzene molecules solubilized near the micelle-water interface and that the solubilization sites within the micelles are different as the DTAB concentration is passing through 32.0 mM (hereafter we refer this concentration as the second CMC). The change of solubilization sites is also confirmed by abrupt changes of the chemical shifts and relaxation rates of benzene protons in DATB-benzene system at this concentration. It was revealed from the electrical conductivity and viscosity measurements that the solubilization of benzene caused the DTAB micelles to swell out and that the micelles prepared after the second CMC had a greater swelling effect than those prepared before the second CMC. The transition point which reflects the saturation of benzene molecules on the solubilization sites of micelles was observed at one benzene/micellized DTAB mole ratio from the electrical conductivity measurements. Along the different concentration of DTAB solution, this transition point is appeared clearly after the second CMC. From these results it is suggested that the shapes and/or sizes of DTAB micelles of the spherical micelle region prepared after the second CMC are different from those prepared before the second CMC.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.293-300
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• 2021

This study presents a Power Quality(:PQ) costs calculation methodology based on Value-Based Methodology. A SCDF including Voltage Sag Costs is presented to calculate Sustained Interruption Costs, Momentary Interruption Costs, and Voltage Sags Costs. Authors compared between interruption costs without Back-Up Power Supply and interruption costs with Back-Up Power Supply, and showed reduction of interruption costs by investing Back-UP Power Supply by multi-lateral analyzation. By applying this method to the real system, evaluated and analyzed power quality of the system.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.267-275
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• 2019

Tabriz is a large Iranian city and the capital of the East Azerbaijan province. The bed rock of this city is mainly consisted of marl layers. Marl layers have some outcrops in the northern and eastern parts of city that mainly belong to the Baghmisheh formation. Based on their colors, these marls are classified into three types: yellow, green, and gray marls. The city is developing toward its eastern side wherein various civil projects are under construction including tunnels, underground excavation, and high-rise building. In this regard, the swelling behavior assessment of these marls is of critical importance. Also, in lightweight structures with foundation pressure less than swelling pressure, several problems such as walls cracking and jamming of door and windows may occur. In the present study, physical properties and swelling behavior of Baghmisheh marls are investigated. According to the X-ray diffractometer (XRD) results, the marls are mainly composed of Illite, Kaolinite, Montmorillonite, and Chloride minerals. Type and content of clay minerals and initial void ratio have a decisive role in swelling behavior of these marls. The swelling potential of these marls was investigated using one-dimensional odometer apparatus under stress level up to 10 kPa. The results showed that yellow marls have high swelling potential and expansibility compared to the other marls. In addition, green and gray marls showed intermediate and low swelling potential and swelling pressure, respectively.

• Journal of IKEEE
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• v.23 no.1
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• pp.99-106
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• 2019

This paper propose a new form of UPQC (Unified Power Quality Compensator) to compensate the current and voltage quality problems of nonlinear loads. The conventional UPQC system consists of a series inverter, a parallel inverter, and a common DC link. A new type of UPQC proposed is a parallel compensator with SVC (Static Var Compensator) added to compensate for the wide compensation range and low DC link voltage. The parallel inverter compensates the reactive power generated by the nonlinear load, and the series inverter compensates the sag and swell generated at the power supply side.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.34-41
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• 2021

Interventional radiology and minimally invasive surgery both require a precisely shaped microcatheter. Microcatheters are manufactured using polymer extrusion processes with a die and puller. The manufacturing parameters and die geometry greatly influence the profile of the extrudate and designing dies using a trial-and-error process is expensive and requires a lot of time. Therefore, predicting the profile of the extrudate is important for manufacturing microcatheters. This study investigates the effects of die design and geometry on the profile of the extrudate. The profiles of the extrudate are predicted using ANSYS Polyflow with respect to the different die geometries. The outer and inner diameters and wall thickness of the predicted extrudate are compared to those of a target extrudate. The die swell of melt polymer and the effect of the pulling are both examined. Optimized die designs are suggested for manufacturing the target extrudate.

• The Journal of Korean Institute of Information Technology
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• v.17 no.9
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• pp.11-17
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• 2019

In recent years, damage and loss of life and property have been occurred frequently due to swelling waves in the East Sea. Swelling waves are not easy to predict because they are caused by various factors. In this research, we build a model for predicting the swelling waves occurrence in the East Coast of Korea using machine learning technique. We collect historical data of unloading interruption in the Pohang Port, and collect air pressure, wind speed, direction, water temperature data of the offshore Pohang Port. We select important variables for prediction, and test various machine learning prediction algorithms. As a result, tide level, water temperature, and air pressure were selected, and Random Forest model produced best performance. We confirm that Random Forest model shows best performance and it produces 88.86% of accuracy

• Korean Journal of Environmental Agriculture
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• v.19 no.5
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• pp.375-381
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• 2000

Quantifying the changes of soil microbial biomass and activity of enzymes are important to understand the dynamics of active soil C and N pools. The dynamics of soil microbial biomass C and N and the activity of enzymes over entire growth period of soybean-(Glycine max (L) Merr.)-wheat (Triticum aestivum L.) sequence on a Typic Haplustert as influenced by organic manure and inorganic fertilizer N were investigated in a field experiment. The application of farmyard manure at 4 to 16 $Mg{\cdot}ha^{-1}\;y^{-1}r^{-1}$ along with fertilizer nitrogen at 50 or 180 $kg{\cdot}ha^{-1}$ increased the mean soil microbial biomass from 1.12 to 2.05 fold over unmanured soils under soybean-wheat system. Irrespective of organic and chemical fertilizer N application, the soil microbial biomass was maximum during the first two months at active growing stage of the crops and subsequently declined with crop maturity. The mean annual microbial activity was significantly increased when manure and chemical fertilizer at 8 $Mg{\cdot}ha^{-1}$ and 50/180 N $kg{\cdot}ha^{-1}$, respectively were applied. The C turnover rate decreased by 47 to 72 % when the level of farmyard manure was increased from 4 to 8 and 16 $Mg{\cdot}ha^{-1}$. There were significant correlations between biomass C, available N, dehydrogenase, phosphatase and yield of the crops.

• Geomechanics and Engineering
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• v.31 no.3
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• pp.305-318
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• 2022

Permeable reactive barriers used for groundwater treatment require proper estimation of the reactive material behavior regarding the emplacement method. This study evaluates the dry emplacement of zeolite (clinoptilolite) to be used as a reactive material in the barrier by carrying out several geotechnical laboratory tests. Dry zeolite samples, exhibited higher wetting-induced compression strains at the higher vertical stresses, up to 12% at 400 kN/m². The swelling potential was observed to be limited with a 3.5 swell index and less than 1% free swelling strain. Direct shear tests revealed that inundation reduces the shear strength of a dry zeolite column by a maximum of 10%. Falling head permeability tests indicate decreasing permeability values with increasing the vertical effective stress. Regarding self-loading and inundation, the porosity along the zeolite column was calculated using a proposed 1D numerical model to predict the permeability with depth considering the laboratory tests. The calculated discharge efficiency was significantly decreased with depth and less than 2% relative to the top for barrier depths deeper than 20 m. Finally, the importance of directional dependence in the permeability of the zeolite medium for calibrating 2D finite element flow analysis was highlighted by bench-scale tests performed under 2D flow conditions.

• International journal of advanced smart convergence
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• v.13 no.3
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• pp.66-79
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• 2024

The model developed in this study holds significant importance in predicting carbon emissions in maritime transport. By utilizing ship data and EEDI (Energy Efficiency Design Index) guidelines, the model presents a highly accurate prediction tool, providing a solid foundation for maximizing operational efficiency and effectively managing carbon emissions in ship operations. The model's accuracy was demonstrated by an R² score of 0.95 and a Mean Absolute Percentage Error (MAPE) of 1.4%. Through SHAP (SHapley Additive exPlanations) and Partial Dependence Plots (PDP), it was identified that Speed Over Ground and relative wind speed are the most significant variables, both showing a positive correlation with increased CO2 emissions. Additionally, environmental factors such as exceeding an average draft of 22(m), a Leeway over 5°, and a current angle exceeding 200° were found to increase emissions significantly. Specific ranges of wind and swell wave angles also notably affected emissions. Conversely, lower pitch, roll, and rudder angle were associated with reduced emissions, indicating that stable ship operation enhances efficiency.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.552-557
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• 2001

By UV-irradiation of Eremothecium ashbyii DTl, a higWy flavinogenic mutant (UV-18-57) and a nonflavinogenic mutant (UV -85) were obtained. The physio-morphological characteristics of these three strains were studied on glucose medium in submerged fermentation. Glucose utilization and mycelial growth occurred in 0 - 2 days of fermentation. By the third day, the biomass had declined. Extracellular riboflavin excretion was distinct from the second day, reaching a maximum rate by the fourth day. The hyphae of the highly flavinogenic mutant UV-18-57 were broader than DTl, while the nonflavinogenic UV-85 hyphae were very thin. Riboflavin accumulation was high in UV-18-57 (extracellular riboflavin,$825\mu\textrm{g}/ml$ , and intracellular, $490\mu\textrm{g}/ml$) and caused the mycelia to swell into bulbous forms. Riboflavin accumulation was less in DTl ($108\mu\textrm{g}/ml$ extracellular and $24\mu\textrm{g}/ml$ intracellular) and correspondingly its hyphae were thinner than those of UV-18-57 and swollen bulbous mycelia were not prominent. UV-85 was nonflavinogenic and, accordingly, its mOlphological characteristics included long thin filaments with no intracellular riboflavin accumulation. A large number of greenish fluorescence spores were seen in UV-18-57, whereas DTI had less spores and UV-85 was nonsporulating. Sporulation is correlated with riboflavin production. UV-18-57 had better mycelial integrity and lysis started only by the seventh day, whereas DTI and UV -85 started to lyze earlier by 4 -5 days. By the late stage of fermentation (eighth day), DTl had a few long, thin filaments indicating some secondary growth, whereas UV -85 showed a compact pellet form of mycelia. Most mycelia of UV-18-57 still appeared intact.