• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.114-114
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• 2014

We present our activities linking to planning of possible forms of large program to study on circumstellar H2O and SiO maser sources with KaVA. A great advantage of KaVA for the stellar maser observations is the combination of the unique capability of the multi-frequency phase referencing technique of KVN and the dual-beam astrometry of VERA with the KaVA's relative dense antenna configuration. We have demonstrated this advantage through the test observations conducted by the KaVA Evolved Stars Sub-working Group since 2012 March. Snapshot KaVA imaging is confirmed to be possible in integration time of 0.5 hour at the 22 GHz band and 1.0 hour at the 43 GHz band in typical cases. This implies that large snapshot imaging surveys towards many H2O and SiO stellar masers are possible within a reasonable machine time (e.g., scans on ~100 maser sources within 200 hours). This possibility enables us to select the maser sources, which are suitable for future long-term (10 years) intensive (biweekly-monthly) monitoring observations, from 1000 potential target candidates selected from dual-frequency band (K/Q-bands) KVN single-dish observations. The output of the survey programs will be used for statistical analysis of the structures of individual stellar maser clumps and the spatio-kinematical structures of circumstellar envelopes with accelerating outflows. The combination of astrometry in milliarcsecond(mas) level and the multi-phase referencing technique yields not only trigonometric parallax distances to the masers but also precise position reference for registration of different maser lines. The accuracy of the map registration affects interpretation of the excitation mechanism of the SiO maser lines and the origin of the variety of the maser actions, which are expected to reflect periodic behaviors of the circumstellar envelope with stellar pulsation. Currently we are checking the technical feasibility of KaVA operations for this combination. After this feasibility test, the long-term monitoring campaign program will run as one of KaVA's legacy projects.

• KSBB Journal
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• v.14 no.6
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• pp.661-664
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• 1999

Proteins were extracted from an aqueous phase with reversed micelles. The effect of pH, and salt concentration on the solubilization of lysozyme in AOT/isooctane solution was studied to explore the potential for employing this solvent system in the large-scale recovery and concentration of proteins using liquid extraction. For pH values below the isoelectric point, pl of the protein, solubilization was high, probably owing to strong electrostatic interactions between the positively charged proteins and the anionic surfactant heads forming the inner micelle wall. At low ionic strength complete solubilization of the protein was observed. A pH higher than the pl of lysozyme and a salt concentration lower than that of the water pool were required for the recovery aqueous phase to ensure the back extraction of lysozyme from the AOT reversed micelles.

• The Journal of Korean Medicine
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• v.32 no.3
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• pp.25-34
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• 2011

Objectives: We performed simultaneous determination of five constituents by HPLC in Samul-tang (SMT). Additionally, we investigated the immune-stimulatory potential of SMT on specific cellular and humoral immune responses in ovalbumin (OVA)-immunized mice. Methods: Reverse-phase chromatography using a Gemini C18 column operating at $40^{\circ}C$, and photodiode array (PDA) detection at 190-400 nm, were used for quantification of the five components of SMT. Mobile phase using a gradient flow consisted of two solvent systems. Solvent A was 1.0% (v/v) aqueous acetic acid and solvent B was acetonitrile with 1.0% (v/v) acetic acid. C57BL/6 mice were immunized intraperitoneally with OVA/alum ($100{\mu}g/200{\mu}g$) on days 1, 8, and 15. The extract of SMT (1000 mg/kg) was given to mice orally for 21 days (from day 1 to day 21). At day 22, OVA-, lipopolysaccharide (LPS)- and concanavalin A (Con A)-stimulated splenocyte proliferation and OVA-specific and total antibodies were measured in plasma. Results: Calibration curves were acquired with $r^2$>0.9999, and the relative standard deviation (RSD, %) for intra- and inter-day precision were both less than 3.5%. The recovery was in the range of 95.69-115.12%, with an RSD less than 6.0%. The contents of five components in SMT were 1.08-15.30 mg/g. SMT significantly enhanced Con A-induced splenocyte proliferation in OVA-immunized mice (p<0.01). Also, SMT significantly enhanced OVAspecific IgG, IgG1 and total IgM levels in plasma compared with the OVA-immunized group. Conclusions: The established method will be applied for the quantification of major components and immunestimulating activity in OVA-immunized mouse model of SMT.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.673-679
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• 2016

Because of the growing interest in supercritical carbon dioxide power cycle technology owing to its potential enhancement in compactness and efficiency, supercritical carbon dioxide cycles have been studied in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. This study introduces the current status of the research project on the supercritical carbon dioxide power cycle by Korea Institute of Energy Research (KIER). During the first phase of the project, the un-recuperated supercritical Brayton cycle test loop was built and tested. In phase two, researchers are designing and building a supercritical carbon dioxide dual Brayton cycle, which utilizes two turbines and two recuperators. Under the simulation condition considered in this study, it was confirmed that the design parameter has an optimal value for maximizing the net power in the supercritical carbon dioxide dual cycle.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.141-148
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• 2011

Support vector machines have been extensively studied and utilized in pattern recognition area for years. One of interesting applications of this technique is music/speech classification for a standardized codec such as 3GPP2 selectable mode vocoder. In this paper, we propose a novel approach that improves the speech/music classification of support vector machines. While conventional support vector machine optimization techniques apply during training phase, the proposed technique can be adopted in classification phase. In this regard, the proposed approach can be developed and employed in parallel with conventional optimizations, resulting in synergistic boost in classification performance. We first analyze the impact of kernel width parameter on the classifications made by support vector machines. From this analysis, we observe that we can fine-tune outputs of support vector machines with the kernel width parameter. To make the most of this capability, we identify strong correlation among neighboring input frames, and use this correlation information as a guide to adjusting kernel width parameter. According to the experimental results, the proposed algorithm is found to have potential for improving the performance of support vector machines.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2178-2182
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• 2011

Recently, the synthesis of ordered macroporous materials has received much attention due to its potential use as photonic band gap materials.$^1$ In this study, we have used the three-dimensional (3D) latex array template impregnated with benzenesulfonic acid (BSA), which is capable of catalyzing the reaction using tetraethyl orthosilicate (TEOS) as a precursor and distilled water. The polystyrene (PS) templates were reacted with TEOS in $scCO_2$ at 40 $^{\circ}C$ and at 80 bar. In the reactor, TEOS was filtrated into the PS particle lattice. After the reaction, porous silica materials were obtained by calcinations of the template. The stability test of the PS template in pure $CO_2$ was conducted before the main experiment. Scanning electron microscopy (SEM) images showed that the reaction in $scCO_2$ takes place only on the particle surface. This new method using $scCO_2$ has advantages over conventional sol-gel processes in its capability to control the fluid properties such as viscosity and interfacial tension. It has been found that the reaction in $scCO_2$ occurs only on the particle surface, making the proposed technique as more rapid and sustainable method of synthesizing inverse opal materials than conventional coating processes in the liquid phase and in the vapor phase.

• The Journal of Korean Obstetrics and Gynecology
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• v.28 no.2
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• pp.26-39
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• 2015

Objectives : Dendropanax morbifera is known as a tree that has been used in traditional medicine for various diseases. However, its biological activities in cancer have not yet been clearly elucidated. In this study, we investigated the anti-cancer effects of water extract of Dendropanax morbifera (DP) on 2 human breast cancer cell lines (estrogen dependent MCF-7 and estrogen independent MDA-MB-231). Methods : The MTT assay and flow cytometry were used to assess cell proliferation, along with cell cycle analysis. Nitric oxide production was detected by Griess assay. The expression of apoptosis related gene was assessed by quantitative real-time PCR. Results : Our data revealed that DP inhibits the cell growth in a dose dependent manner (0, 50, 100, 250, and 500 μg/ml) of both estrogen independent MDA-MB-231 and estrogen dependent MCF-7 breast cancer cells. Also, LPS induced nitric oxide production was significantly reduced by DP. Cell cycle analysis showed an increased G1 phase in the MCF-7 cell and G2/M phase in the MDA-MB-231 cell. DP decreased mRNA expression of apoptotic suppressor gene Bcl-xL, and increased mRNA expression of pro-apoptotic genes. DP increased mRNA expression of p21, and Rip1 in both cell. And DP decreased mRNA expression of survivin in the MCF-7 cell. Conclusions : Taken together, these results indicate that DP extract are source of anti-cancer potential and could be developed botanical drug.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.248-257
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• 2020

This study presents an initial design for a novel system consisting in a coupled nuclear reactor and a phase change material-based thermal energy storage (TES) component, which acts as a buffer and regulator of heat transfer between the primary and secondary loops. The goal of this concept is to enhance the capacity factor of nuclear power plants (NPPs) in the case of high integration of renewable energy sources into the electric grid. Hence, this system could support in elevating the economics of NPPs in current competitive markets, especially with subsidized solar and wind energy sources, and relatively low oil and gas prices. Furthermore, utilizing a prismatic-core advanced high temperature reactor (PAHTR) cooled by a molten salt with a high melting point, have the potential in increasing the system efficiency due to its high operating temperature, and providing the baseline requirements for coupling other process heat applications. The present research studies the neutronics and thermal hydraulics (TH) of the PAHTR as well as TH calculations for the TES which consists of 300 blocks with a total heat storage capacity of 150 MWd. SERPENT Monte Carlo and MCNP5 codes carried out the neutronics analysis of the PAHTR which is sized to have a 5-year refueling cycle and rated power of 300 MW_th. The PAHTR has 10 metric tons of heavy metal with 19.75 wt% enriched UO₂ TRISO fuel, a hot clean excess reactivity and shutdown margin of $33.70 and -$115.68; respectively, negative temperature feedback coefficients, and an axial flux peaking factor of 1.68. Star-CCM + code predicted the correct convective heat transfer coefficient variations for both the reactor and the storage. TH analysis results show that the flow in the primary loop (in the reactor and TES) remains in the developing mixed convection regime while it reaches a fully developed flow in the secondary loop.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.73-85
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• 2007

In this study, the experiment of solid-phase microextraction (SPME) technique using GC/FID was conducted as a possible alternative to liquid-liquid extraction for the analysis of EGBE, DGBE, DBM and TGME in water, and also, an optimization condition of trace analysis for disel oxygenates including EGBE by the design of experiment (DOE) was described. Experiments used a fractional factorial design method followed by central composite design allowing optimization of a number of factors as well as statistical analysis of the results. The response surface analysis showed that the extraction efficiency could be represented by a second-order polynomial equation in which the salts concentration, extraction temperature, extraction time and sonication time are the major influences. Using DOE method, a new datadependent method was developed to improve the quantity of confidently analyzed disel oxygenates in water samples.

• Progress in Superconductivity and Cryogenics
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• v.20 no.3
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• pp.21-27
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• 2018

It is difficult to fabricate and maintain moving parts of expander at cryogenic temperature. This paper describes numerical analysis and experimental investigation on a cryogenic reciprocating expander without moving piston. An intake valve which takes high-pressure gas, and an exhaust valve which discharges low-pressure gas, are connected to a tube. The inside pressure of the tube is pulsated for work production. This geometric configuration is similar to that of pulse tube refrigerator but without regenerator. An orifice valve and a reservoir are installed to control the phase of the mass flow and the pressure. At the warm end, a heat exchanger rejects the heat which is converted from the produced work of the expanded gas. For the numerical analysis, mass conservation, energy conservation, and local mass function for valves are used as the governing equations. Before performing cryogenic experiments, we carried out the expander test at room temperature and compared the performance results with the numerical results. For cryogenic experiments, the gas is pre-cooled by liquid nitrogen, and then it enters the pulse tube expander. The experiments are controlled by the opening of the orifice valve. Numerical analysis also found the expander conditions that optimize the expander performance by changing the intake pressure and valve timing as well as the opening of the orifice valve. This paper discusses the experimental data and the numerical analysis results to understand the fundamental behavior of such a newly developed non-mechanical expander and elucidate its potential feature for cryogenic application.