• Economic and Environmental Geology
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• v.21 no.3
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• pp.235-255
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• 1988

Talc deposit of pipe-like form occurrs in the lower part of the Hyangsanri Dolomite with a strike of N40 -50 E and a dip of 40 -50 NW which is one formation of the Ogcheon Super Croup. The pipi-like ore body plunge at about $40^{\circ}$ to the west and are parallel to the lineation developed in the area. Structural formulae of tales occurred in this deposit are close to the ieal composition $Mg_6Si_8O_{20}(OH)_4$ showing limited deviation from ideal one. Substitution of Al for Si in tetrahedral site is of little or nothing ranging 0-0.04 and octahedral occupancy is close to six ranging 5.88-5.98 atoms per unit cell. Predominant octahedaral cation is Mg and proportion of divalent cations is generally over 97percent. Calcite -dolomite thermometry is obtained by determining the mol % $MgCO_3$using of EPMA and XRD methods. The peak metamorphic temperature can be estimated at $470{\pm}30^{\circ}C$ in the area whereas carbonates occurred at near talc ore show lower temperature than $400^{\circ}C$ that the calcite solvus limit is not well established. It indicates that the talc deposit was formed at the lower temperature that the metamorphic temperature. Cosequently, the formation of talc by metamorphism is questionable and the alteratin zone developed around the talc ore is very limited. The occurrence of talc ore in the dolomite as well as mineralogy, calcite-dolomite geothermometry, chlorite geothermometry, field and microscopic evidence suggest that siliceous ascending hydrothermal solution along the fracture is responsible for the formation of talc. It was considered that the slight fracturing of dolomite was formed by deformation prior to the mineralization.

• Tribology and Lubricants
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• v.35 no.5
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• pp.300-309
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• 2019

Gas foil thrust bearings (GFTBs) support axial loads in oil-free, high speed rotating machinery using air or gas as a lubricant. Due to the inherent low viscosity of the lubricant, GFTBs often have super-laminar flows in the film region at operating conditions with high Reynolds numbers. This paper develops a mathematical model of a GFTB with turbulent flows and validates the model predictions against those from the literature. The pressure distribution, film thickness distribution, load carrying capacity, and power loss are predicted for both laminar and turbulent flow models and compared with each other. Predictions for an air lubricant show that the GFTB has high Reynolds numbers at the leading edge where the film thickness is large and relatively low Reynolds numbers at the trailing edge. The predicted load capacity and power loss for the turbulent flow model show little difference from those for the laminar flow model even at the highest speed of 100 krpm, because the Reynolds numbers are smaller than the critical Reynolds number. On the other hand, refrigerant (R-134a) lubricant, which has a higher density than air, had significant differences due to high Reynolds numbers in the film region, in particular, near the leading and outer edges. The predicted load capacity and power loss for the turbulent flow model are 2.1 and 2.3 times larger, respectively, than those for the laminar flow model, thus implying that the turbulent flow greatly affects the performance of the GFTB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1013-1018
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• 2021

Due to the recent accident caused by the automated vehicle, discussions on the ethical aspects of AI have been actively underway. This paper confirms that AI is inevitably connected to ethical components through the concepts and techniques related to robots-AI, and argues that ethical aspects are built-in, not post facto. Furthermore, this devises a solution to the trolley dilemma that can serve as a clue to ethical problems associated with automated vehicles. Preferentially, that process contains writing Bayesian networks. Next, only important and influential data are left after the pre-processing stage, and crowd-sourcing & extrapolation is used to calculate the exact figures of the networks. Through this process, this argues that humans' subjects are certainly included in implementing algorithms and models and discusses the necessity and direction of engineering liberal arts, especially education of ethics that distinguished from major education to prevent distortions and biases abouts AI systems.

• Journal of Broadcast Engineering
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• v.27 no.5
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• pp.694-702
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• 2022

This paper is the UX-based technology strategy research which is a solution to how conversational AI can be ethically evolved in the Metaverse environment. Since conversational AI influences people's on-offline decision-making factors through interaction with people, the Metaverse AI ethics must be reflected. In the machine learning process of conversational AI, cultural codes along with user's personal experience data must be included and considered to reduce the error value of user experience. Through this, the super-personalized Metaverse service can evolve ethically with social values. With above hypothesis as a result of the study, a conceptual model of a forward-looking perspective was developed and proposed by adding user experience data to the machine learning (ML) process for context-based interactive AI in the Metaverse service environment.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.310-323
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• 2023

The k-eigenvalue neutronics/thermal-hydraulics coupling calculation is a key issue for reactor design and analysis. Jacobian-free Newton-Krylov (JFNK) method, featured with super-linear convergence rate and high efficiency, has been attracting more and more attention to solve the multi-physics coupling problem. However, it may converge to the high-order eigenmode because of the multiple solutions nature of the k-eigenvalue form of multi-physics coupling issue. Based on our previous work, a modified JFNK with a line search method is proposed in this work, which can find the fundamental eigenmode together with thermal-hydraulics feedback in a wide range of initial values. In detail, the existing modified JFNK method is combined with the line search strategy, so that the intermediate iterative solution can avoid a sudden divergence and be adjusted into a convergence basin smoothly. Two simplified 2-D homogeneous reactor models, a PWR model, and an HTR model, are utilized to evaluate the performance of the newly proposed JFNK method. The results show that the performance of this proposed JFNK is more robust than the existing JFNK-based methods.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.52.4-53
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• 2020

It is less well known that the properties, especially the mass accretion rate, of accretion flow are affected by the angular momentum of accreting gas. Park (2009) found that the mass accretion rate \dot{m}, mass accretion rate in units of Bondi accretion rate, is inversely proportional to the angular momentum of gas λ, at the Bondi radius where gas sound speed is equal to the free-fall velocity and proportional to the viscosity parameter α, and also Narayan & Fabian (2011) found a similar relation, but the dependence of the mass accretion rate of the gas angular momentum is much weaker. In this work, we investigate the global solutions for the rotating Bondi flow, i.e., polytropic flow accreting via viscosity, for various accretion parameters and the dependence of the mass accretion rate on the physical characteristics of gas. We set the outer boundary at various radius r_{out}=10^3~10^5 r_{Sch}, where r_{Sch} is the Schwarzschild radius of the black hole. For a small Bondi radius, the mass accretion rate changes steeply, as the angular momentum changes, and for a large Bondi radius, the mass accretion rate changes gradually. When the accreting gas has a near or super Keplerian rotation, we confirm that the relation between the mass accretion rate and angular momentum is roughly independent of Bondi radius as shown in Park (2009). We find that \dot{m} is determined by the gas angular momentum at the Bondi radius in units of r_{Sch}c. We also investigate the solution for the rotating Bondi flow with the outflow. The outflow affects the determination of the mass accretion rate at the outer boundary. We find that the relation between the mass accretion and the gas angular momentum becomes shallower as the outflow strengthens.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.33-40
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• 2023

As South Korea enters the realm of an super-aging society, the demand for elderly welfare services has been steadily rising. However, the current shortage of welfare personnel has emerged as a social issue. To address this challenge, there is active research underway on elderly care robots designed to mitigate the social isolation of the elderly and provide emergency contact capabilities in critical situations. Nonetheless, these functionalities require direct user contact, which represents a limitation of conventional elderly care robots. In this paper, we propose a solution to overcome these challenges by introducing a care robot system capable of interacting with users without the need for direct physical contact. This system leverages commercialized elderly care robots and cameras. We have equipped the care robot with an edge device that incorporates facial expression recognition and action recognition models. The models were trained and validated using public available data. Experimental results demonstrate high accuracy rates, with facial expression recognition achieving 96.5% accuracy and action recognition reaching 90.9%. Furthermore, the inference times for these processes are 50ms and 350ms, respectively. These findings affirm that our proposed system offers efficient and accurate facial and action recognition, enabling seamless interaction even in non-contact situations.

• Korean Journal of Materials Research
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• v.7 no.2
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• pp.129-135
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• 1997

This study has investigated the effects of aging treatment on thc nlechanical propcrries of blg-iiAl-x%nix - 0.1.2) alloys fabricated by the squeeze castmg process. The microstructurcs of as-squeeze cast were composed of pro eurectic $\alpha$ magnesium solid solution, super saturated $\alpha$ solid solution and $\beta(Mg_{17}AI_{12}$) compund. Agcd at both $200^{\circ}C$ and $240^{\circ}C$, Mg--6AixZn alloys showed the peak hardness due to the formation of $\beta(Mg_{17}AI_{12}$) precipitates. The tiiscontinuous precipitates of the lamella r\.pe are predominant at $200^{\circ}C$ aging tredrment. tvhilc. the finely dispersed continu ous precipitates were major type at $240^{\circ}C$ treatment. Mg-- GAI-xZn a1loi.s fabricated hy the squeeze casting process had the hetter combination of tensile strength and elongation compared to the conventionally cast alloys. As increascci zinc: contents. the tensile strength was increased 11y the soiid solutirin strengthening effect of zinc,.

• Korean Journal of Crystallography
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• v.16 no.1
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• pp.43-53
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• 2005

The dihydrido P-C-P pincer complex, $IrH_2{C_6H_3-2,6-(CH_2PBu_2^t)_2}$ (1), was successfully prepared from the reaction of the hydrochloride complex, $IrClH (C_6H_3-2,6-(CH_2PBu_2^t)_2}$, and super acid $(LiBEt_3H)$ under 1 atm of hydrogen in pentane solution at room temperature and followed by Heating at $130^{\circ}C$ in vacuo. Jensen recently found that the dihydrido P-C-P pincer complex 1 is a highly active homogeneous catalyst for the transfer dehydrogenation of alkanes with unusual longterm stability at temperatures as high as $200^{\circ}C$. The treatment of dihydrido complex 1 with nitrogen, water, carbon dioxide, and carbon monoxide in presence of tert-butylethylene (the) at room temperature in an appropriate solution gave the dinitrogen complex, $[Ir{C-6H_3-2,6-(CH_2PBu_2^t)_2}]_2({\mu}-N_2)$ (2), the hydrido hydroxyl complex, $IrH(OH){C_6H_3-2,6-(CH_2PBu_2^t)_2}$ (3), the carbon dioxide complex, $Ir({\eta}^2-CO_2) {C_6H_3-2,6-(CH_2PBu_2^t)_2}$ (including the bicarbonate complex, $IrH({\kappa}^2-O_2COH){C_6H_3-2,6-(CH_2PBu_2^t)_2}\;(4))$, and the carbonyl complex, $Ir(CO) {C_6H_3-2,6-(CH_2PBu_2^t)_2}\;(5)$ (including the carboxyl complex, $IrH(C(O)OH) {C_6H_3-2,6-(CH_2PBu_2^t)_2}\;(6))$, in good yield, respectively. These P-C-P iridium complexes were isolated and characterized by $^1H,\;^{13}C,\;^{31}P\; NMR$, and IR spectroscopy. In addition, the complexes (1-6) were characterized by a single crystal X-ray crystallography. These complexes account for these small molecules' inhibition of dehydrogenation of alkanes catalyzed by the dihydrido complex 1.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.3
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• pp.174-186
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• 2007

Amphora coffeaeformis and Achnanthes longipes are commonly found as dominant benthic microalgae in Jeju coastal water throughout the year. In order to investigate pharmaceutical uses of these diatoms, each single species was isolated with micropipette under phase contrast microscope and subcultured with synthetic seawater media which was enriched with F/2 media, trace metal solution and $Na_2SiO_3$). Growth characteristics of these species were also determined with different combination of salinity, nutrients concentration and temperature. Thereafter, mass culture of each species was done based on the maximum growth condition. Biomass was collected after two weeks of mass culture and freeze dried for antioxidant study. The antioxidant properties of different fractions (n-hexane, chloroform and ethylacetate) obtained by solvent fractionation of 80% methanolic extract of two microalgae were investigated for free radical, reactive oxygen species scavenging (Super oxide, Hydrogen peroxide, Hydroxyl radical and Nitric oxide), metal chelating and lipid peroxidation inhibition activities. All fractions of A. longipes showed higher $DPPH^{\cdot}$ (free radical) scavenging activities (n-hexane: 89.0%, Chloroform: 76.0%, Ethylacetate: 66.0%, Methanol: 90.6% and aqueous residue: 63.0%). N-hexane fraction of A. longipes showed significantly higher activity (49.0%) on nitric-oxide. Ethylacetate fraction of A. longipes and aqueous residue of A. coffeaeformis exhibited 64.0% and 75.6% metal chelating activity which was higher than commercial antioxidants (${\alpha}$-tocopherol: 18.0% and BHT: 16.0%). The n-hexane fraction of A. coffeaeformis had 67.5% activity on $DPPH^{\cdot}$. Chloroform and n-hexane fractions of A. coffeaeformis exhibited 46.2% and 47.6% $H_2O_2$ scavenging effects which were closely similar to commercial antioxidants (${\alpha}$-tocopherol: 49.2% and BHT: 58.6%). Chloroform and ethylacetate fractions of A. longipes and fraction of n-hexane and chloroform of A. coffeaeformis showed better lipid peroxidation activities than ${\alpha}$-tocopherol. These data suggest that both organic and aqueous fractions have good antioxidative compounds with different antioxidant properties.