• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.11-18
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• 2020

High-pressure synchrotron X-ray powder diffraction experiments were performed on natural illite (K_0.65Al₂(Al_0.65Si_3.35)O₁₀(OH)₂) using diamond anvil cell (DAC) under two different pressure transmitting media (PTM), i.e., water and ME41 (methanol:ethanol = 4:1 by volume). When using water as PTM, occasional heating was applied up to about 250℃ while reaching pressure up to 2.7 GPa in order to promote both hydrostatic conditions and intercalation of water molecules into the layer. When using ME41, pressure was reached up to 6.9 GPa at room temperature. Under these conditions, illite did not show any expansion of interlayer distance or phase transitions. Pressure-volume data were used to derive bulk moduli (K₀) of 45(3) GPa under water and 51(3) GPa under ME41 PTM. indicating no difference in compressibility within the analytical error. Linear compressibilities were then calculated to be β^a = 0.0025, β^b = 0.0029, β^c = 0.0144 under ME41 PTM showing the c-axis is ca. six times more compressible than a- and b-axes. These elastic behaviors of illite were compared to muscovite, one of its structural analogues.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.254-270
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• 2020

We conducted a seasonal field survey to analyze the distribution patterns of a phytoplankton community and biological oceanographic characteristics in the Geum river estuary in 2018. The results showed that the phytoplankton community consisted of 58 genera and 116 species, showing a relatively simple distribution. It was controlled by diatoms at 70.2%, a low number of species in winter and spring, and a high number in summer and autumn. The phytoplankton cell density ranged from 10.0 to 2,904.0 cells mL^-1, with an average layer of 577.2 cells mL^-1, which was low in autumn and high in winter. The seasonal succession of phytoplankton dominant species was mainly centric diatoms from winter to summer, including Thalassiosira nordenskioeldii, Cerataulina bergonii, and Skeletonema costatum-ls in winter, S. costatum-ls and C. bergonii in spring, and Eucampia zodiacus and Th. nordenskioeldii in summer. However, the autumn species depended upon the regions, with the inner bay dominated by the centric diatom, Aulacoseira cf. granulata, the mixed areas by S. costatum-ls, and the open sea by the dinoflagellate, Lingulodinium polyedra. According to principal component analysis (PCA), the phytoplankton community was greatly affected by the inflow and expansion of freshwater, including high nutrients, which are introduced annually through the rivermouth weir in Geum river estuary. However, the estuary, which is strongly affected by annual freshwater, was limited to areas near Geumran Island, which is adjacent to the river-mouth weir.

• Journal of the Korean Ceramic Society
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• v.43 no.6 s.289
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• pp.369-375
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• 2006

[ $(Ba_{0.5}Sr_{0.5})_{0.99}Co_{x}Fe_{1-x}O_{3-{\delta}}$ ] [x=0.8, 0.2](BSCF) powders were synthesized by a Glycine-Nitrate Process (GNP) and the electrochemical performance of the BSCF cathode on a scandia stabilized zirconia, $[(Sc_{2}O_3)_{0.11}(ZrO_2)_{0.89}]-1Al_{2}O_3$ was investigated. In order to prevent unfavorable solid-state reactions between the cathode and zirconia electrolyte, a GDC ($Gd_{0.1}Ce_{0.9}O_{2-{delta}}$) buffer layer was applied on ScSZ. The BSCF (x = 0.8) cathode formed on GDC(Buffer)/ScSZ(Disk) showed poor electrochemical property, because the BSCF cathode layer peeled off after the heat-treatment. On the other hand, there were no delamination or peel off between the BSCF and GDC buffer layer, and the BSCF (x = 0.2) cathode exhibited fairly good electrochemical performances. It was considered that the observed phenomenon was associated with the thermal expansion mismatch between the cathode and buffer layer. The ohmic resistance of the double layer cathode was slightly lower than that of the single layer BSCF cathode due to the incorporation of platinum particle into the BSCF second layer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.809-819
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• 2004

In this paper, in order to exclude the expansion of M/W relay frequency or its new frequency assignment possibly, we analyzed a possibility of substituting M/W system by B-WLL or optical fiber network regarding service quality and economical points. To define the target of service quality, pre-condition and analysis method for the selected media have been derived to compare each other. E1 transmission with BER 10$^{-1}$ was chosen as a reference capacity, and service distance was calculated f3r the selected media as a function of availability. Also from the economical point we considered 3 systems such as optical fiber, M/W, and B-WLL based upon basic system structure, and analyzed them for various line configurations of fiber optic and B-WLL according to service period, system capacity, transmission distance, and data rate. It was confirmed that B-WLL can provide quality of service with 99.999 % availability within 1.6 km cell radius, and for optical fiber substitution, the leased fiber conduit on an electric pole is more economical than M/W system irrespective of service period, but in case of directly digging for underground conduit, it turned out ineffective regardless of cabling duct types.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.187-194
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• 2012

The strength of particle-reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic-plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite-element unit cell model. The proposed method is shown to be very effective by performing finite-element strength analysis of $SiC_p$/Al2124-T4 composites that included ductile failure in the matrix and particlematrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle-reinforced metal matrix composites.

• Journal of Distribution Science
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• v.11 no.10
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• pp.17-25
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• 2013

Purpose - This study analyzes the effect of customers' perceived service innovativeness of service centers for electronic goods, on repurchase intentions of customers, using behavior intentions of service centers as a mediator variable. In customer management and customer relationship marketing, service centers can be the most representative customer relationship management departments because they are most closely placed at the interface with customers. In addition, this study intends to investigate if continuous relationship with customers during one-time product-selling can affect their repurchase intentions. Specifically, this research aims to investigate if the expansion of the saturated physical market of the manufacturing business, to intangible service markets, can be competitive enough to satisfy customer needs. Research design, data, and methodology - This study targets college students, and especially those who have computers, digital cameras, or cell-phones, and often use electronic products and services. In order to investigate our hypothesis, we analyzed dates through SEM (structural equation modeling) using SPSS for Windows 18.0 and AMOS 18.0. In addition, we measured Cronbach's α coefficient using SPSS for Windows 18.0 in order to measure reliability. Further, using AMOS 18.0, this research statistically measured convergent validity as well as discriminant validity, and examined mediation models and path models in which service innovativeness leads to customers' repurchase intentions of electronic products. Results - As a result, this research shows that customers' perceived service innovativeness of service centers for electronic goods has significant positive influence on customers' behavior intentions of service centers. In addition, service innovativeness of electronic goods' service centers also has significant positive influence on repurchase intentions of customers. Conclusion - This study investigates the effect of customers' positive relation with the innovativeness of electronic service center on their behavior intention and product repurchase. The more concrete, important results of the study are as follows. Through the mediating effect, the findings of the study suggest that customers' behavior intentions of service centers partially mediate the effect of customers'perceived service innovativeness of service centers for electronic goods on customers' repurchase intentions. This research also provides an insight that the importance of service innovativeness and innovative approaches in managing customers should be recognized in the process of repurchase and service roles of manufacturing business as a way for customer management. As a result, the relationship between customer satisfaction and service quality of service centers for the electronic products is very sensitive. Although previous studies focus on certain aspects of the case for enhancing service innovation (Kim, 2012), this research recommends that the service centers need to understand the customers'desire first and try to adapt to achieve customer satisfaction by being innovative. This innovativeness of service centers would make customers visit them consistently, which in the long run, will also influence their repurchase decisions.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.478-478
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• 2012

Recently, there are many researches in order to increase the deposition rate (D/R) and improve film uniformity and quality in the deposition of microcrystalline silicon thin film. These two factors are the most important issues in the fabrication of the thin film solar cell, and for the purpose of that, several process conditions, including the large area electrode (more than 1.1 X 1.3 (m2)), higher pressure (1 ~ 10 (Torr)), and very high frequency regime (VHF, 40 ~ 100 (MHz)), have been needed. But, in the case of large-area capacitively coupled discharges (CCP) driven at frequencies higher than the usual RF (13.56 (MHz)) frequency, the standing wave and skin effects should be the critical problems for obtaining the good plasma uniformity, and the ion damage on the thin film layer due to the high voltage between the substrate and the bulk plasma might cause the defects which degrade the film quality. In this study, we will propose the new concept of the large-area multi-electrode (a new multi-electrode concept for the large-area plasma source), which consists of a series of electrodes and grounds arranged by turns. The experimental results with this new electrode showed the processing performances of high D/R (1 ~ 2 (nm/sec)), controllable crystallinity (~70% and controllable), and good uniformity (less than 10%) at the conditions of the relatively high frequency of 40 MHz in the large-area electrode of 280 X 540 mm2. And, we also observed the SEM images of the deposited thin film at the conditions of peeling, normal microcrystalline, and powder formation, and discussed the mechanisms of the crystal formation and voids generation in the film in order to try the enhancement of the film quality compared to the cases of normal VHF capacitive discharges. Also, we will discuss the relation between the processing parameters (including gap length between electrode and substrate, operating pressure) and the processing results (D/R and crystallinity) with the process condition map for ${\mu}c$-Si:H formation at a fixed input power and gas flow rate. Finally, we will discuss the potential of the multi-electrode of the 3.5G-class large-area plasma processing (650 X 550 (mm2) to the possibility of the expansion of the new electrode concept to 8G class large-area plasma processing and the additional issues in order to improve the process efficiency.

• Korean Journal of Ecology and Environment
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• v.44 no.1
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• pp.85-94
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• 2011

Present study aimed to investigate the effect of zinc accumulation on the tissues of Carassius auratus with various rearing condition. Heavy metal, Zn, was accumulated in the gill, bone and muscle increased for exposure period of 40 days. Moreover, the accumulated concentration of Zn in the gill showed relatively higher than that in other tissues. Also, activities of antioxidant enzymes in the gill, kidney, liver and muscle tissues after exposure to Zn were increased in the manner of exposure period. Antioxidant enzyme activities were shown higher in the gill and muscle than those in the kidney and liver tissues. The gill of C. auratus showed abnormal shapes in its secondary lamellae by long time exposure condition and determined the increased numbers of mucous cells in gill exposed to Zn. In addition, the edema, the exfoliation of epithelial cell was shown in the gill and membrane damages were observed in mitochondria and nucleus. In the kidney, we observed not only the atrophied glomerulus, but the expansion of empty space in Bowman's capsule. Based on the above results, it is considered that the exposure to the high level of Zn for long period possibly involves in the decrease of respiratory and excretory rates, giving rise to secondary lesion of tissues.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.306-310
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• 2005

The comparison in release rate constant and properties of extracts from extruded raw ginseng and extruded white ginseng was conducted to apply extrusion process for manufacturing of released ginseng tea bag. Dry raw ginseng and white ginseng powder were extruded at 20∼30% moisture content and 200∼300 rpm by using an experimental twin-screw extruder. Browness and redness (both indicated the releasing of saponin and ginsenosides) were increased with the increase in the screw speed and the decrease of moisture content. Crude saponin and water solubility index (WSI) of both ginseng also share the same behaviour against the level of screw speed and moisture content, as well as browness and redness. The particle size effects of extruded raw ginseng at 20% and 28% moisture content on absorbance of released extract at 260 up to 560 nm, WSI, and water absorption index were determined. While particle size decreased from 800∼1000 nm to 200∼500 nm, absorbance and WSI are decreased. Absorbance and WSI shown increasing level while moisture content was decreased. In conclusion, the formation of pores by expansion and disruption of cell wall in extrusion cooking were obviously responsible to increase the amount of released extract of extruded ginseng and its WSI as well. The extrusion process turns out be the efficient process for manufacturing of commercial ginseng tea product than those of other thermal processes.

• Journal of the Korean Institute of Gas
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• v.18 no.4
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• pp.13-20
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• 2014

In natural gas distribution system, gas pressure is regulated correspond to requirement using throttle valve which is releasing huge pressure energy as useless form. The waste pressure can be recovered by using turbo machinery devices such as a turbo expander. In this process, excessive temperature drop occurs due to Joule-Thompson effect during the expansion process. Installing natural gas boiler before or after the turbo expander prevents temperature drop. Fuel cell or gas engine hybrid system further improve the efficiency, but 1~2% of total transporting natural gas is used for operating the hybrid system. In this study, a heat pump system is proposed as a preheating device which can be operated without using transporting natural gas. Thermodynamic analysis on evaporating and condensing temperatures and refrigerants is conducted. Results show that R717 is proper refrigerant for the hybrid system with high COP and low turbine work within the defined operating conditions. In domestic usage in Korea, the heat pump system has more economic feasibility owing to natural gas being imported with a high price of LNG form.