• Journal of the Mineralogical Society of Korea
• /
• v.10 no.1
• /
• pp.33-44
• /
• 1997

The reaction path of water-gneiss in 200m borehole at the Soorichi site of Yugu Myeon, Chungnam was simulated by the EQ3NR/EQ6 program. Mineral composition of borehole core and fracture-filling minerals, and chemical composition of groundwater was published by authors. In this study, chemical evolution of groundwater and formation of secondary minerals in water-gneiss system was modelled on the basis of published results. The surface water was used as a starting solution for reaction. Input parameters for modelling such as mineral assemblage and their volume percent, chemical composition of mineral phases, water/rock ratio reactive surface area, dissolution rates of mineral phases were determined by experimental measurement and model fit. EQ6 modelling of the reaction path in water-gneiss system has been carried out by a flow-centered flow through open system which can be considered as a suitable option for fracture flow of groundwater. The modelling results show that reaction time of 133 years is required to reach equilibrium state in water-gneiss system, and evolution of present groundwater will continue to pH 9.45 and higher na ion concentration. The secondary minerals formed from equeous phase are kaolinite, smectite, saponite, muscovite, mesolite, celadonite, microcline and calcite with uincreasing time. Modeling results are comparatively well fitted to pH and chemical composition of borehole groudwater, secondary minerals identified and tritium age of groundwater. The EQ6 modelling results are dependent on reliability of input parameters: water-rock ratio, effective reaction surface area and dissolution rates of mineral phases, which are difficult parameters to be measured.

• Korean Journal of Mineralogy and Petrology
• /
• v.34 no.1
• /
• pp.15-29
• /
• 2021

In the Arctic Ocean, the distribution of sea ice and ice sheets changes as climate changes. Because the distribution of ice cover influences the mineral composition of marine sediments, studying marine sediments transported by sea ice or iceberg is very important to understand the global climate change. This study analyzes marine sediment samples collected from the Arctic Ocean and infers the provenance of the sediments to reconstruct the paleoenvironment changes of the western Arctic. The analyzed samples include four gravity cores collected from the Araon mound in the Chukchi Plateau and one gravity core collected from the slope between the Araon mounds. The core sediments were brown, gray, and greenish gray, each of which corresponds to the characteristic color of sediments deposited during the interglacial/glacial cycle in the western Arctic Ocean. We divide the core sediments into three units based on the analysis of bulk mineral composition, clay mineral composition, and Ice Rafted Debris (IRD) as well as comparison with previous study results. Unit 3 sediments, deposited during the last glacial maximum, were transported by sea ice and currents after the sediments of the Kolyma and Indigirka Rivers were deposited on the continental shelf of the East Siberian Sea. Unit 2 sediments, deposited during the deglacial period, were from the Kolyma and Indigirka Rivers flowing into the East Siberian Sea as well as from the Mackenzie River and the Canadian Archipelago flowing into the Beaufort Sea. Unit 2 sediments also contained an extensive amount of IRD, which originated from the melted Laurentide Ice Sheet. During the interglacial stage, fine-grained sediments of Unit 1 were transported by sea ice and currents from Northern Canada and the East Siberian Sea, but coarse-grained sediments were derived by sea ice from the Canadian Archipelago.

• 한국체육학회지인문사회과학편
• /
• v.58 no.5
• /
• pp.201-217
• /
• 2019

The purpose of this study was to consider composition of the movement program for the elderly with dementia to develop visit-customized movement program. For the study, 20 experts were selected including 8 dance therapists, 2 dementia-specialized doctors, 5 physical education leaders of the elderly, and 5 geriatric care helpers. First Delphi data, which listed items, was used to analyze content. Second and third Delphi questionnaires, which evaluated importance in Likert scale, was used to calculate content validity rate, average, standard deviation, quartile, convergence degree, and concurrence degree of each composition. 46 core composition of movement program for the elderly, which were selected and highlighted by the experts, were departmentalized into 6 considered compositions of movement program. 7 required composition of movement program, 1 Appropriate frequency of 3 times in a week and 1 30 minutes for each exercise, 1 operation method, 5 appropriate exercise of rhythm expression, 4 appropriate aerobic exercise, 4 appropriate muscle exercises, 5 appropriate stretches, 3 appropriate partner exercises 4 Appropriate massages, 5 appropriate tools

• Journal of the Korean Magnetics Society
• /
• v.12 no.6
• /
• pp.218-223
• /
• 2002

We investigated the magnetic properties of High Flux-type $Ni_{x}Fe_{100-x}$(x=40∼50, wt.％) permalloy powders and dust cores. The powder was prepared by conventional gas atomization in mass production scale. At the composition of $Ni_{x}Fe_{55}$, saturation magnetization was maximum. In case of lower Ni content than X=45, the $M_{s}$, decreased largely with the decrease in Ni content, which is due to the invar effect. The permeability of compressed powder cores increased with the decrease in Ni content, which was considered to be due to the decrease in the magnetostriction. In addition, the dust core with Ni=45％ showed the lowest core loss because of the increase in electrical resistivity leading to the low eddy current loss. From the better frequency dependence of permeability, larger Q value and superior DC bias characteristics of Ni=45％ than those of Ni=50％ core, it was confirmed that the 45％Ni-55％Fe powder alloy was better material for the dust core than commercial High Flux core materials.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.10
• /
• pp.825-829
• /
• 2015

Theoretical calculations suggest that the thermoelectric figure of merit (ZT) can be improved by introducing a core-shell heterostructure to a semiconductor nanowire because of the reduced thermal conductivity of the nanowire. To experimentally verify the decrease in thermal conductivity in core-shell nanowires, the thermal conductivity of Ge-SixGe1-x core-shell nanowires grown by chemical vapor deposition (CVD) was measured using suspended microdevices. The silicon composition (Xsi) in the shells was measured to be about 0.65, and the remainder of the germanium in the shells was shown to play a role in decreasing defects originating from the lattice mismatch between the cores and shells. In addition to the standard four-point current- voltage (I-V) measurement, the measurement configuration based on the Wheatstone bridge was attempted to enhance the measurement sensitivity. The measured thermal conductivity values are in the range of 9-13 W/mK at room temperature and are lower by approximately 30 than that of a germanium nanowire with a comparable diameter.

• The Korean Journal of Quaternary Research
• /
• v.25 no.2
• /
• pp.17-24
• /
• 2011

We investigated the variation of $CaCO_3$ contents in cores PC1 and PC2 recovered from the continental slope area of the Ulleung Basin in the East Sea. $CaCO_3$ contents of cores PC1 and PC2 varied between 0.6 and 17.2% and between 0.3 and 43.0%, respectively. $CaCO_3$ contents in the upper part of core PC1 corresponding to MIS 1 are less than 5%, whereas those in the lower part of MIS 2 are more than 10%. Such variation of $CaCO_3$ contents in core PC1 confirms the previous results of $CaCO_3$ studies in the East Sea. In core PC2, $CaCO_3$ contents of the upper part are similar to those of core PC1. However, $CaCO_3$ contents in the lower part of core PC2 are more than 40%. According to XRD operation and SEM examination, the high $CaCO_3$ contents in the lower part of core PC2 are more attributable to the authigenic carbonate minerals rather than the biogenic carbonate composition. Such abundant authigenic carbonate minerals are closely related to the dissociation of methan hydrates which were observed in the Ulleung Basin.

• Nuclear Engineering and Technology
• /
• v.41 no.5
• /
• pp.617-648
• /
• 2009

Under the government supported long-term nuclear R&D program, the severe accident research program at KAERI is directed to investigate unresolved severe accident issues such as core debris coolability, steam explosions, and hydrogen combustion both experimentally and numerically. Extensive studies have been performed to evaluate the in-vessel retention of core debris through external reactor vessel cooling concept for APR1400 as a severe accident management strategy. Additionally, an improvement of the insulator design outside the vessel was investigated. To address steam explosions, a series of experiments using a prototypic material was performed in the TROI facility. Major parameters such as material composition and void fraction as well as the relevant physics affecting the energetics of steam explosions were investigated. For hydrogen control in Korean nuclear power plants, evaluation of the hydrogen concentration and the possibility of deflagration-to-detonation transition occurrence in the containment using three-dimensional analysis code, GASFLOW, were performed. Finally, the integrated severe accident analysis code, MIDAS, has been developed for domestication based on MELCOR. The data transfer scheme using pointers was restructured with the modules and the derived-type direct variables using FORTRAN90. New models were implemented to extend the capability of MIDAS.

• Health Policy and Management
• /
• v.20 no.1
• /
• pp.137-154
• /
• 2010

This study empirically analyzed the effects of the Top Management Team (TMT) on organizational performance. We verified whether the age heterogeneity, job heterogeneity (core career, core function and major), and process (communication and integration) of the TMT affect organizational performance (management performance and healthcare service quality evaluation level). We collected data about 473 members of the 2006 TMT in 81 medical institutions. We also utilized statistics of organizational performance from the Ministry for Health, Welfare and Family Affairs and the Korean Institute of Hospital Management. Results of the study showed that the age heterogeneity of TMT exerted a negative effect on the healthcare service quality evaluation level, while the process exerted a positive effect. However, the age heterogeneity, job heterogeneity, and process had no influence on management performance. We discussed the implications of such outcome of the investigation in comparison with the former studies on TMT and organizational performance, and presented its restrictions and future plans.

• Macromolecular Research
• /
• v.14 no.2
• /
• pp.209-213
• /
• 2006

The ring-opening polymerization of D,L-lactide initiated by tin(II) 2-ethylhexanoate $(Sn(Oct)_2)$ on the surface-initiated magnetite $(Fe_{3}O_4)$ nanoparticles was performed at $130^{\circ}C$. The effects of the polymer molar mass and concentration on the amount of surface polymer were investigated. The number average molecular weights, $M_n$, obtained by both NMR and GPC methods fit well within the accuracy of the applied methods and ranged from 1,100 to $4,040g\;mol^{-1}$. A surface functionalization density of up to 625 initiation sites per particle was obtained. The composition of various core-shell particles was determined by TGA, with results indicating magnetite $(Fe_{3}O_4)$ contents, ${\mu}m$, between 17 and 59 wt%. Under the influence of a magnetic field, the heating generated by superparamagnetic core-shell particles suspended in toluene presented guidelines for an optimization of magnetic particle systems with respect to an application for hyperthermia.

• Journal of the Korean Ceramic Society
• /
• v.39 no.6
• /
• pp.594-597
• /
• 2002

Silicon Oxynitride(SiON) thick films on p-type silicon(100) wafers have obtained by using plasma-enhanced chemical vapor deposition from SiH$_4$ , N$_2$O and N$_2$. Prism coupler measurements show that the refractive indices of SiON layers range from 1.4620 to 1.5312. A high deposition power of 180 W leads to deposition rates of up to 5.92${\mu}$m/h. The influence of the deposition condition on the chemical composition was investigated using X-ray photoelectron spectroscopy. After deposition of the SiON thick films, the films were annealed at 1050$^{\circ}C$ in a nitrogen atmosphere for 2 h to remove absorption band near 1.5${\mu}$m.