• Geophysics and Geophysical Exploration
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• v.14 no.3
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• pp.227-233
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• 2011

Attention has been focused on geothermal energy as an alternative energy because it is continuously operable without external supply. Most of geothermal anomalies in Korea are related to deep circulation of groundwater through a fracture system in granite area. Therefore it is very important to understand the distribution of the fracture system which is the main channel of ground water. In this research, we constructed the velocity models with a fracture system and the layered sediments, respectively, and generated synthetic data sets with them to verify the presented vertical seismic profiling (VSP) preprocessing scheme. We compared the results from conventional VSP preprocessing flow to those from VSP preprocessing flow considering fracture system. We noticed that the preprocessing flow considering fracture system retains more sufficient signal including down-going wave than conventional preprocessing. In addition, we applied 3D VSP prestack phase screen migration to the preprocessed reversed VSP (RVSP) data from Seokmo Island so that we were able to image fracture structure of the geothermal site in Seokmo Island.

• Membrane Journal
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• v.33 no.4
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• pp.191-200
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• 2023

Polyethersulfone (PES) is a widely employed membrane material for water and industrial purification applications owing to its hydrophilicity and ease of phase separation. However, PES membranes and filters prepared using the nonsolvent induced phase separation method often encounter significant flux decline due to pore clogging and cake layer formation on the dense membrane surfaces. Our investigation revealed that tight microfiltration or loose ultrafiltration membranes can be subject to physical fouling due to the formation of a dense skin layer on the bottom side caused by water intrusion to the gap between the shrank membrane and the substrate. To investigate the effect of the bottom surface porosity on membrane fouling, two membranes with the same selective layers but different sub-layer structures were prepared using single and double layer casting methods, respectively. The double layered PES membrane with highly porous bottom surface showed high flux and physical fouling tolerance compared to the pristine single layer membrane. This study highlights the importance of physical optimization of the membrane structure to prevent membrane fouling.

• Journal of Korea Water Resources Association
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• v.56 no.spc1
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• pp.1059-1069
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• 2023

Dam-break flow occurs when an elevated dam suddenly collapses, resulting in the catastrophic release of rapid and uncontrolled impounded water. This study compares laminar and turbulent closure models for simulating three-dimensional dam-break flows using OpenFOAM. The Reynolds-Averaged Navier-Stokes (RANS) model, specifically the k-ε model, is employed to capture turbulent dissipation. Two scenarios are evaluated based on a laboratory experiment and a modified multi-layered block obstacle scenario. Both models effectively represent dam-break flows, with the turbulent closure model reducing oscillations. However, excessive dissipation in turbulent models can underestimate water surface profiles. Improving numerical schemes and grid resolution enhances flow recreation, particularly near structures and during turbulence. Model stability is more significantly influenced by numerical schemes and grid refinement than the use of turbulence closure. The k-ε model's reliance on time-averaging processes poses challenges in representing dam-break profiles with pronounced discontinuities and unsteadiness. While simulating turbulence models requires extensive computational efforts, the performance improvement compared to laminar models is marginal. To achieve better representation, more advanced turbulence models like Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) are recommended, necessitating small spatial and time scales. This research provides insights into the applicability of different modeling approaches for simulating dam-break flows, emphasizing the importance of accurate representation near structures and during turbulence.

• (The) Research of the performance art and culture
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• no.22
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• pp.93-121
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• 2011

This article is concerned with the withdrawal of the compositional principle of Jinogigut which has been performed in Seoul and the identification of its meaning based on the withdrawal. Jinogigut is a world where a god is connected to humans in complicated manners, this world and the world of the dead coexist, and it is a process of demonstrating that the dead, who have stayed in the world of humans, enter the world of a god. Jinogigut shows the process of leading the dead to the world of the dead one after another. First, the god-centered street is continued, and the gut displays through which process a god will guide the dead to the world of the dead. Next, is a human-centered street, which exhibits the appearance of the dead heading to the world of the dead following the death angel, more in detail. Finally, a human-centered structure shows how humans enter the world of the dead. Through this repetition, it reveals that the dead take a seat in the world of the dead, at last. The organization of the later part of the world of the dead-oriented gut in Jinogigut, which is god-centered, continues to a human-centered gut through the meeting between a god and humans. and , which are continued, followed by , are ceremonial rituals that confirm the dead entering the world of the dead without any problem. Begareugi shows that the entering of the dead into the world of the dead was completed with perfection by cutting hemp cloth, and informs the living that the dead expressed gratitude for holding the ritual for him/her by appearing at the venue of the gut once again and that the dead settled into the world of death. , which finally holds ancestral rites to the god of ancestors who is seated in the world of the dead, reveals that the dead, who had been a human, has been transformed into the god of ancestors through Jinogigut. Jinogigut also performs the function of comforting a client (who is the family of the dead) of the gut, who has faced a sudden death in his/her family. What is the most important for consoling the client is to display that the dead has entered the world of the dead without any problem. Jinogigut shows this process through a three-layered structure. It exhibits how the dead would be moved to the world of gods, as well as the safe entering of the dead who followed Jeoseung-saja(envoy from the world of the dead) and who had appeared to this world from the world of the dead. Then, it demonstrates again the appearance of the dead entering the world of the dead following Barigongu; thus, it placates the heart of the client's family.

• Membrane Journal
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• v.22 no.2
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• pp.113-119
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• 2012

$YBaCo_2O_{5+{\delta}}$ oxide was synthesized by solid state reaction and a typical dense membrane has been prepared using as-prepared powder by unilateral pressing and sintering at $1,180^{\circ}C$. The $YBaCo_2O_{5+{\delta}}$ membraneswas analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). XRD analysis showed the double layered perovskite structure was observed over $1,150^{\circ}C$ without impurities. Oxygen permeation was measured in the temperature range from 750 to $950^{\circ}C$ according to oxygen partial pressure difference between feed and permeation side. The oxygen permeation flux increased with increasing temperature and oxygen partial pressure and the maximum oxygen flux of $YBaCo_2O_{5+{\delta}}$ membrane with 1.0 mm thickness was about 0.15 mL/$cm^2{\cdot}min$ at $950^{\circ}C$ and $PO_2$ = 0.42 atm. The activation energy for oxygen permeation decreased with decreasing oxygen partial pressure to be 76.0 kJ/mol at the condition of $PO_2$ = 0.21 atm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.3
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• pp.99-105
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• 2014

$LiCoO_2$ thin film have received attention as cathodes of thin-film microbatteries. In this study, $LiCoO_2$ thin films were synthesized on Au substrates by sol-gel spin coating method and electrochemical properties were investigated under annealing temperature and time. The phycochemical properties of $LiCoO_2$ thin film were investigated by X-ray diffraction, scaning electron microscopy and atomic force microscopy. The electrochemical properties were characterized using galvanostatic charging/discharging cycling tests. From X-ray diffraction, as-grown films annealed at $550^{\circ}C$ and $750^{\circ}C$ are presumed to be spinel structure and a single phase of the layered-rock-salt, respectively. The RMS roughness and grain size of the films which annealed at $750^{\circ}C$ has similar values for annealing time 10 and 30 min, while for annealing time 120 min surface roughness, grain size increase and pore appearance were observed. The first discharge capacity of $LiCoO_2$ thin films annealed at $750^{\circ}C$ for 10, 30 and 120 min is about 54.5, 56.8 and $51.87{\mu}Ah/cm^2{\mu}m$, respectively. Corresponding capacity retention at 50th cycle is 97.25, 76.69, 77.19%.

• The KIPS Transactions:PartB
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• v.11B no.1
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• pp.83-90
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• 2004

Strategic games are missing special qualities of genre these days. Game engines neither reason about behaviors of computer objects nor have learning ability that can prepare countermeasure in variously command user's strategy. This paper suggests a strategic game engine that applies non-monotonic reasoning and inductive machine learning. The engine emphasizes three components -“user behavior monitor”to abstract user's objects behavior,“learning engine”to learn user's strategy,“behavior display handler”to reflect abstracted behavior of computer objects on game. Especially, this paper proposes two layered-structure to apply non-monotonic reasoning and inductive learning to make behaviors of computer objects that learns strategy behaviors of user objects exactly, and corresponds in user's objects. The engine decides actions and strategies of computer objects with created information through inductive learning. Main contribution of this paper is that computer objects command excellent strategies and reveal differentiation with behavior of existing computer objects to apply non-monotonic reasoning and inductive machine learning.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.403-414
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• 1994

Nonlinear analysis of RC containment structure under thermal load and pressure is presented to trace the behaviour after an assumed LOCA. The temperature distribution varying with time through the wall thickness is determined by transient finite element analysis with the two time level scheme in time domain. The layered shell finite elements are used to represent the containment structures in nuclear power plants. Both geometric and material nonlinearities are taken into account in the finite element formulation. The constitutive relation of concrete is modeled according to Drucker-Prager yield criteria in compression. Tension stiffening model is used to represent the tensile behaviour of concrete including bond effect. The reinforcing bars are modeled by smeared layer at the location of reinforcements accounting elasto-plastic axial behaviors. The steel liner model under Von Mises yield criteria is adopted to represent elastic-perfect plastic behaviour. Geometric nonlinearity is formulated to consider the large displacement effect. Thermal stress components are determined by the initial strain concept during each time step. The temperature differential between any two consecutive time steps is considered as a load incremental. The numerical results from this study reveal that nonlinear temperature gradient based on transient thermal analysis will produces excessive large displacement. Nonlinear behavior of containment structures up to ultimate stage can be traced reallistically. The present study allows more realistic analysis of concrete containment structures in nuclear power plants.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.3-8
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• 1988

Nonstoichiometric solid solutions of the $Sr_{1+x}Dy_{1-x}FeO_{4-y}$ system (x = 0. 00, 0. 25, 0. 50, 0. 75 and 1. 00) with layered $K-2NiF_4$ type structure were prepared at 1200$^{\circ}$C under atmospheric pressure. X-ray powder diffraction spectra show that the crystallographic phases of the samples are tetragonal within the x range. Nonstoichiometric chemical formulas have been determined by Mohr salt analysis and it shows that the amount of $Fe^{4+}$ ion or ${\tau}$ value increases with increasing x. Electrical conductivities of the samples which were measured in the temperature range of $-100{\sim}200^{\circ}$C under atmospheric air pressure are varied within the semiconductivity range of $l0^{-8}{\sim}10^{-2}(ohm^{-1}{\cdot}cm^{-1}$) and the activation energies are also varied from 0.02 to 0.08 eV. Mixed valency state of $Fe^{3+}$ and $Fe^{4+}$ in the sample of $Sr_{1.00}Dy_{1.00}FeO_{4.04}$ was identified again by Mossbauer spectrum at 200K.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.6
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• pp.683-689
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• 2006

Statement of problem. Interfacial toughness is important in the mechanical property of layered dental ceramics such as core-veneered all-ceramic dental materials. The interfaces between adjacent layers must be strongly bonded to prevent delamination, however the weak interface makes delamination by the growth of lateral cracks along the interface. Purpose. The purpose of this study was to determine the effect of the reaction layer on the interfacial fracture toughness of the core/veneer structure according to the five different divesting. Materials and methods. Thirty five heat-pressed Lithia-based ceramic core bars (IPS Empress 2), $20mm{\times}3mm{\times}2mm$ were made following the five different surface divesting conditions. G1 was no dissolution or sandblasting of the interaction layer. G2 and G3 were dissolved layer with 0.2% HF in an ultrasonic unit for 15min and 30 min. G4 and G5 were dissolved layer for 15min and 30min and then same sandblasting for 60s each. We veneered bilayered ceramic bars, $20mm{\times}2.8mm{\times}3.8mm$(2mm core and 1.8mm veneer), according to the manufacturer's instruction. After polishing the specimens through $1{\mu}m$ alumina, we induced five cracks for each of five groups within the veneer close to interface under an applied indenter load of 19.6N with a Vickers microhardness indenter. Results. The results from Vickers hardness were the percentage of delamination G1:55%, G2:50%, G3:35%, G4:0% and G5:0%. SEM examination showed that the mean thickness of the reaction layer were G1 $93.5{\pm}20.6{\mu}m$, G2 $69.9{\pm}14.3{\mu}m$, G3 $59.2{\pm}20.2{\mu}m$, G4 $0.61{\pm}1.44{\mu}m$ G5 $0{\pm}0{\mu}m$. The mean interfacial delamination crack lengths were G1 $131{\pm}54.5{\mu}m$, G2 $85.2{\pm}51.3{\mu}m$, and G3 $94.9{\pm}81.8{\mu}m$. One-way ANOVA showed that there was no statistically significant difference in interfacial crack length among G1, G2 and G3(p> 0.05). Conclusion. The investment reaction layer played important role at the interfacial toughness of body ceramic bonded to Lithia-based ceramic.