• Proceedings of the Optical Society of Korea Conference
• /
• 2007.02a
• /
• pp.26-27
• /
• 2007

• Proceedings of the Optical Society of Korea Conference
• /
• 2006.02a
• /
• pp.145-146
• /
• 2006

• Journal of the Korean Geosynthetics Society
• /
• v.19 no.2
• /
• pp.23-33
• /
• 2020

This study determines the basic properties and acid rock drainage generation capacity of Pohang tertiary mudstone through laboratory experiments. According to X-ray fluorescence (XRF) analysis results, the mudstone of this area mostly comprised of SiO₂ with a proportion of approximately 60%, followed in order by Al₂O₃ and Fe₂O₃. As such, it is clear that there is an abundance of aluminosilicates with a high probability of generating acid rock drainage. The XRD analysis showed that the mudstone contains pyrite (FeS₂), it is highly likely to generate acid rock drainage, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis results showed that the mudstone samples contained a high amount of Fe²⁺ ions. As a result of anion analysis measured by ion chromatography (IC), all mudstone samples were measured to have high SO^2-₄ concentrations. According to elemental analysis, the total sulfur (S) content was high, which in turn indicates a high risk of acid rock drainage generation reflected by a maximum potential acidity (MPA) higher than 1%. All in all, although there were slight deviations between the tertiary mudstone samples, overall, the samples exhibited high acid rock drainage generation capacities.

• Korean Journal of Optics and Photonics
• /
• v.8 no.5
• /
• pp.377-381
• /
• 1997

Poling condition in 2 mol% MgO-doped $LiNbO_3$ crystals is investigated by varying the amplitude of poling electric field from 3V/cm to 7V/cm. It is found that 5V/cm is the best value for the formation of single domain by analysing the characteristics of the second harmonic generation(SHG) as the function of temperature. The temperature dependence of the phase-matching profile of SHG for the crystal applied by a spatially modulated electric field is observed to be very different from the simple sinc function. The distorted profile can be consistently fitted with the numerical simulations. This shows that the crystal homogeneity can be tested by the SHG temperature phase-matching profile. In addition, the thermo birefringence coefficient and electro birefringence coefficient of SHG were measured from the temperature dependence of phase-matching profile and shifts of phase-matching temperature by appling electric field along c-axis.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.240.2-240.2
• /
• 2013

The device scale of flash memory was confronted with quantum mechanical limitation. The next generation memory device will be required a break-through for the device scaling problem. Especially, graphene is one of important materials to overcome scaling and operation problem for the memory device, because ofthe high carrier mobility, the mechanicalflexibility, the one atomic layer thick and versatile chemistry. We demonstrate the hybrid memory consisted with the metal-oxide quantum dots and the mono-layered graphene which was transferred to $SiO_2$ (5 nm)/Si substrate. The 5-nm thick secondary $SiO_2$ layer was deposited on the mono-layered graphene by using ultra-high vacuum sputtering system which base pressure is about $1{\times}10^{-10}$ Torr. The $In_2O_3$ quantum dots were distributed on the secondary $SiO_2$2 layer after chemical reaction between deposited In layer and polyamic acid layer through soft baking at $125^{\circ}C$ for 30 min and curing process at $400^{\circ}C$ for 1 hr by using the furnace in $N_2$ ambient. The memory devices with the $In_2O_3$ quantum dots on graphene monolayer between $SiO_2$ thin films have demonstrated and evaluated for the application of next generation nonvolatile memory device. We will discuss the electrical properties to understating memory effect related with quantum mechanical transport between the $In_2O_3$ quantum dots and the Fermi level of graphene layer.

• Proceedings of the Optical Society of Korea Conference
• /
• 2008.02a
• /
• pp.289-290
• /
• 2008

• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.5
• /
• pp.353-358
• /
• 2013

To develop preferential CO oxidation reaction (PROX) catalyst for small scale hydrogen generation system, supported Pt catalysts have been applied for the target reaction. The supports were systematically changed to optimize supported Pt catalysts. $Pt/Al_2O_3$ catalyst showed the highest CO conversion among the catalysts tested in this study. This is due to easier reducibility, the highest dispersion, and smallest particle diameter of $Pt/Al_2O_3$. It has been found that the catalytic performance of supported Pt catalysts for PROX depends strongly on the reduction property and depends partly on the Pt dispersion of supported Pt catalysts. Thus, $Pt/Al_2O_3$ can be a promising catalyst for PROX for small scale hydrogen generation system.

• The Journal of Korean Institute of Next Generation Computing
• /
• v.13 no.4
• /
• pp.40-51
• /
• 2017

Recently, as mobile workloads are becoming more data-intensive, high data bandwidth is required for mobile memory which also consumes non-negligible system energy. A variety of researches and technologies are under development to improve and optimize mobile memory technologies. However, a comprehensive study on the latest mobile memory technologies (LPDDR or Wide I/O) has not been extensively performed yet. To construct high-performance and energy-efficient mobile memory systems, quantitative and detailed analysis of these technologies is crucial. In this paper, we simulate the computer system which adopts mobile DRAM technologies (Wide I/O and LPDDR3). Based on our detailed and comprehensive results, we analyze important factors that affect performance and energy-efficiency of mobile DRAM technologies and show which part can be improved to construct better systems.

• Natural Product Sciences
• /
• v.17 no.2
• /
• pp.90-94
• /
• 2011

An in vitro bioassay-guide revealed that the methanol (MeOH) extract of the whole plant of Patrinia saniculaefolia (Valerianaceae) showed cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) dual inhibitory activity by assessing their effects on the production of prostaglandin $D_2$ ($PGD_2$) and leukotriene $C_4$ ($LTC_4$) in mouse bone marrow-derived mast cells (BMMCs). Phytochemical study of the MeOH extract of this plant led to the isolation of twelve compounds; ${\beta}$-farnesene (1), squalene (2), nardostachin (3), patridoid I (4), patridoid II (5), patridoid II-A (6), oleanolic acid (7), oleanonic acid (8), 23-hydroxyursolic acid (9), oleanolic acid 3-O-${\alpha}$-L-arabinopyranoside (10), oleanolic acid 3-O-${\beta}$-D-glucopyranoside (11), oleanolic acid 3-O-[${\beta}$-D-xylopyranosyl-(1${\rightarrow}$3)-${\beta}$-D-(6-O-butyl)glucuronopyranoside] (12). Among the compounds, 4 and 5 strongly inhibited both the COX-2-dependent $PGD_2$ generation with $IC_{50}$ values of 8.7 and 13.6 ${\mu}M$, respectively, and the generation of $LTC_4$ in the 5-LOX dependent phase with $IC_{50}$ values of 41.7 and 46.9 ${\mu}M$, respectively, which suggest that the anti-inflammatory activity of P. saniculaefolia might occur in part via the inhibition of both $PGD_2$ and $LTC_4$ generation by 4 and 5.

• Current Applied Physics
• /
• v.18 no.12
• /
• pp.1473-1479
• /
• 2018

Recently multiferroic materials have attract great interest for the applications on memorial, spintronic and magneto-electric sensor devices for their spontaneous magneto-electric coupling properties. Research and development of the various kinds of multiferroics are indispensable factor for a new generation multifunctional materials. In this research, mechanical, electronic, magnetic and nonlinear optical properties of La modified $BiLaFe_2O_6$ (BLFO) and Mn modified $Bi_2FeMnO_6$ (BFMO) were studied as new members of multiferroic $BiFeO_3$ (BFO) series by first-principles calculations, and compared with the pure BFO to discover the optimized properties. Our results show that BLFO and BFMO have good mechanical stability as revealed by elastic constants that satisfy the stability criteria. All these compounds exhibit anisotropic and ductile nature. The enhanced properties by La and Mn substitution, such as increased hardness, improved magnetism, decreased band gap and comparable second harmonic generation responses reveal that the new multiferroic members of BLFO and BFMO would get wider application than their BFO counterpart. Our study is expected to providing an appropriate mechanical reference data as guidance for engineering of high efficiency multifunctional devices with the BFO series.