• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.241-246
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• 2007

Purpose: $[^{11}C]6-OH-BTA-1$ ([N-methyl-$^{11}C$]2-(4'-methylaminophenyl)-6-hydroxybenzothiazole, 1), a -amyloid imaging agent for the diagnosis of Alzheimer's disease in PET, can be labeled with higher yield by a simple loop method. During the synthesis of $[^{11}C]1$, we found the formation of by-products in various solvents, e.g., methylethylketone (MEK), cyclohexanone (CHO), diethylketone (DEK), and dimethylformamide (DMF). Materials and Methods: In Automated radiosynthesis module, 1 mg of 4-aminophenyl-6-hydroxybenzothiazole (4) in 100 l of each solvent was reacted with $[^{11}C]methyl$ triflate in HPLC loop at room temperature (RT). The reaction mixture was separated by semi-preparative HPLC. Aliquots eluted at 14.4, 16.3 and 17.6 min were collected and analyzed by analytical HPLC and LC/MS spectrometer. Results: The labeling efficiencies of $[^{11}C]1$ were $86.0{\pm}5.5%$, $59.7{\pm}2.4%$, $29.9{\pm}1.8%$, and $7.6{\pm}0.5%$ in MEK, CHO, DEK and DMF, respectively. The LC/MS spectra of three products eluted at 14.4, 16.3 and 17.6 mins showed m/z peaks at 257.3 (M+1), 257.3 (M+1) and 271.3 (M+1), respectively, indicating their structures as 1, 2-(4'-aminophenyl)-6-methoxybenzothiazole (2) and by-product (3), respectively. Ratios of labeling efficiencies for the three products $([^{11}C]1:[^{11}C]2:[^{11}C]3)$ were $86.0{\pm}5.5%:5.0{\pm}3.4%:1.5{\pm}1.3%$ in MEK, $59.7{\pm}2.4%:4.7{\pm}3.2%:1.3{\pm}0.5%$ in CHO, $9.9{\pm}1.8%:2.0{\pm}0.7%:0.3{\pm}0.1%$ in DEK and $7.6{\pm}0.5%:0.0%:0.0%$ in DMF, respectively. Conclusion: The labeling efficiency of $[^{11}C]1$ was the highest when MEK was used as a reaction solvent. As results of mass spectrometry, 1 and 2 were conformed. 3 was presumed.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.76.1-76.1
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• 2015

We study the environmental dependence of the mass-size relation especially for the most massive early type galaxies (M>$10^{11.2}M_{\odot}$) in the redshift range 0.15~0.25. As a measure of the environment, galaxy number densities are measured by the $10^{th}$ nearest galaxies within 7000km/s from galaxies with spectroscopic redshifts. We find that galaxies more massive than $10^{11.6}M_{\odot}$ show the environmental dependence in the mass-size relation. The galaxies with M>$10^{11.6}M_{\odot}$ located in the densest, cluster like environment have larger sizes than their counterparts located in a low dense environment. We also find that this environmental dependence of the mass-size relation originates from the brightest cluster galaxies (BCG) rather than non-BCG galaxies. Our result can be explained with a hierarchical growth of the most massive galaxies through dissipation-less merger in dense environments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.97-103
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• 2009

The decompostion characteristics of NAPL TCE in cement/slag/Fe(II) system were studied with various TCE concentration and amounts of binders (cement/slag) For analyses of the TCE degradation by cement/slag/Fe(II), TCE solution injected using gas-tight syringe after TCE solution dissolved a methanol. Initial concentrations of TCE are 0.42 mM, NAPL condition 11.7 mM and saturated condition 16.8 mM respectively. The result showed that the cases of 8.4 mM and 4.2 mM are decreased 88% of total TCE concentration within 18 days. NAPL condition 11.7 mM was decreased 84% within 50 days and saturated condition 16.8 mM was decreased 60% of total TCE concentration within 60 days respectively. This showed that degradations of TCE in various concentrations were in one kind reaction as pseudo-first-order. TCE was dissolved as aqueous solution before degraded. The reaction rate was increased $0.12day^{-1}$, $0.24day^{-1}$, $0.31day^{-1}$ when the mass of media 0.1, 0.2, 0.3 S/L rate was increased. TCE reaction speed is affected by cement/slag surface ares in this system. When HDTMA, experimental facter, was added, TCE decomposition rate was high despite the high concentration of NAPL. and The decompostion characteristics of NAPL TCE in cement/slag/Fe(II) system were studied by using modeling.

• Information and Communications Magazine
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• v.30 no.6
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• pp.20-25
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• 2013

본고에서는 1GHz 이하 주파수에서 동작하는 Wireless LAN(WLAN) 표준으로, IEEE 802.11ah PHY/MAC 표준 규격에 대해서 알아 본다. IEEE 802.11ah 표준은, Smart Grid, M2M, IoT 와 같이 실내, 실외에서 많은 수의 단말들을 최소한의 전력소모로 데이터 통신을 하기 위한 목적으로 개발되었다. WLAN의 서비스 범위가 1Km 이상으로 늘어나게 되면, 그 동안 WLAN 에서 심각하게 다루지 않았던 Hidden Node 문제가 단말의 전력 소모, throughput performance 을 결정하는 중요한 요소로 등장하게 된다. 특별히 IEEE 802.11ah 에서는, 많은 수의 단말들간에 Hidden Node 을 고려한 Restricted Access Window 라는 새로운 channel access 기법이 제안되었고, 이에 본 고에서는 IEEE 802.11ah 에 새롭게 지원되는 MAC 기능들에 대해 중점적으로 살펴 보도록 한다.

• Analytical Science and Technology
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• v.11 no.5
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• pp.409-412
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• 1998

The analytical method to determine europium(III) ion in aqueous solution by fluorescence spectroscopy based upon the conformational change of calmodulin in the presence of the analyte has been studied. The fiber optic chemical sensor used in this study was constructed by entrapping a fluorescein-labeled calmodulin solution, EGTA, buffer solution at the common end of a bifurcated fiber optic bundle by means of a dialysis membrane. The calibration curve to determine europium(III) ion was obtained when concentration of calmodulin, concentration of EGTA, Tris-HCl buffer solution, pH, excitation wavelength and fluorescence wavelength were $5.0{\times}10^{-5}M$, 0.50 mM, 5.0 mM, 7.0, 495 nm and 520 nm, respectively. The detection limit was $1.0{\times}10^{-11}M$ and the working range of the calibration curve for the sensor was $1.0{\times}10^{-11}M{\sim}1.0{\times}10^{-9}M$. The response time was 15 minutes. For the determination of europium(III) ion by the present method, $Na^+$ and $K^+$ ions did not interfere but $Ca^{2+}$ ion seriously interfered.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.11
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• pp.824-831
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• 2008

We present a continuous size-dependent particle separator using a negative dielectrophoretic (DEP) virtual pillar array. Two major problems in the previous size-dependent particle separators include the particle clogging in the mechanical sieving structures and the fixed range of separable particle sizes. The present particle separator uses the virtual pillar array generated by negative DEP force instead of the mechanical pillar array, thus eliminating the clogging problems. It is also possible to adjust the size of separable particles since the size of virtual pillars is a function of a particle diameter and applied voltage. At an applied voltage of 500 kHz $10\;V_{rms}$ (root mean sqaure voltage) sinusidal wave and a flow rate of $0.40\;{\mu}l\;min^{-1}$, we separate $5.7\;{\mu}m$-, $8.0\;{\mu}m$-, $10.5\;{\mu}m$-, and $11.9\;{\mu}m$-diameter polystyrene (PS) beads with separation purity of 95%, 92%, 50%, and 63%, respectively. The $10.5\;{\mu}m$- and $11.9\;{\mu}m$-diameter PS beads have relatively low separation purity of 50% and 63%. However, at an applied voltage of $8\;V_{rms}$, we separate $11.9\;{\mu}m$-diameter PS beads with separation purity over 99%. Therefore, the present particle separator achieves clog-free size-dependent particle separation, which is capable of size tuning of separable particles.

• Nuclear Engineering and Technology
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• v.32 no.1
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• pp.1-9
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• 2000

Delayed hydride cracking (DHC) velocity and threshold stress intensity factor for DHC ($K_{IH}$) tests in the radial direction on M11 pressure tube material in Wolsong unit 1 were carried out following the Atomic Energy Canada Limited (AECL) standard test procedure in order to identify the effect of undercooling on DHCV and to acquire the $K_{IH}$ data. The results showed that $K_{IH}$ 's were 8.8$\pm$0.8 MPa√m in the back offcut and 11.4$\pm$0.7 MPa√m in the front offcut. The fact that $K_{IH}$ in the front offcut is about 20% higher than that in the back offcut is attributed to the microstructural difference between the materials of the front and back ends. $K_{IH}$ 's in M11 pressure tube appeared to be higher than the values from the tubes made of double melted ingot reported earlier. This can be interpreted by the fact that very small amounts of Chlorine (Cl) and Phosphorus (P) are contained in the ingot and that the content of the harmful elements in the M11 pressure tube is equivalent to that made of a quadruple melting process. DHC velocities at 25$0^{\circ}C$ in the front offcut in the radial direction are measured to be 5~8$\times$10$^{-8}$ m/s. The results show that the prior thermal history change the DHC velocity significantly. This effect was confirmed by the experiment of undercooling prior to the DHC tests.DHC tests.

• Korean journal of applied entomology
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• v.45 no.2 s.143
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• pp.161-167
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• 2006

The citrus leafminer (CLM), Phyllocnistis citrella Stainton, is an oligophagous pest of Rutaceae family, especially Citrus spp. occurring in most worldwide citrus-growing areas. This study was conducted to evaluate a sex pheromone chemical of CLM, (Z,Z)-7,11-hexadecadienal (7Z,11Z-16:Al) in monitoring CLM by trap types, the diel activity and the influence of some weather factors on trap catch. CLM was well attracted on a trap baited 7Z,11Z-16:Al 1mg. Sticky wing trap was more effective than bucket trap. Most caught CLM were attracted at 2$\sim$6 a.m. regardless of season, and activity time of CLM was affected by sunrise time as well as sunset time. The trap catch of CLM was more influenced by wind velocity than temperature for activity time of CLM. The number of caught CLM was fallen at below 13$^{\circ}C$, but there was little effect for trap catch at over that temperature. The average wind velocity at over 2.0 m/sec made the number of caught CLM drop down. The precipitation did not affect the number of caught CLM when the average wind velocity was lower than at 2.0 m/sec.

• Journal of Industrial Convergence
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• v.20 no.11
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• pp.35-39
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• 2022

The purpose of this study was to investigate the effect of sea salt on the growth and moisture content of sweet basil, soil moisture content, and salt stress. As a research method, sweet basil was treated with sea salt at 0, 5, 50, 100, and 200 mM concentration of sea salt was investigated to determine the growth and stress time of sweet basil. As a result of the study, it was confirmed that the leaf width increased by 11% when treated with 5 mM, 49% when treated with 50 mM, and 44% when treated with 100 mM. Leaf length was confirmed to grow by 16% at 5 mM, 59% at 50 mM, and 82% at 100 mM treatment. As a future study, based on the effect of sea salt on the leaf and length growth of sweet basil by concentration, it was considered that more research is needed on the beneficial effects of sea salt on edible, medicinal, and aromatic plants. In addition, although salt has only been studied on stress in crops, we intend to contribute to providing basic data for research on ingredients more beneficial to the environment by finding various edible, medicinal, and aromatic plants using the sun-dried salt used in this study.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.2
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• pp.74-78
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• 2018

Purpose $[^{11}C]$acetate has been proved useful in detecting the myocardial oxygen metabolism and various malignancies including prostate cancer, hepatocellular carcinoma, renal cell carcinoma and brain tumors. The purpose of study was to improve the radiosynthesis yield of $[^{11}C]$acetate on a automated radiosynthesis module. Materials and Methods $[^{11}C]$acetate was prepared by carboxylation of grignard reagent, methylmagnesium chloride, with $[^{11}C]$$CO_2$ gas, followed by hydrolysis with 1 mM acetic acid and purification using solid phase extraction cartridges. The effect of the reaction temperature ($0^{\circ}C$, $10^{\circ}C$, $-55^{\circ}C$) and cyclotron beam time (10 min, 15 min, 20 min, 25 min) on the radiosynthesis yield were investigated in the $[^{11}C]$acetate labeling reaction. Results The maximum radiosynthesis yield was obtained at $-10^{\circ}C$ of reaction temperature. The radioactivities of $[^{11}C]$acetate acquired at $-10^{\circ}C$ reaction temperature was 2.4 times higher than those of $[^{11}C]$acetate acquired at $-55^{\circ}C$. Radiosynthesis yield of $[^{11}C]$acetate increased with increasing cyclotron beam time. Conclusion This study shows that radiosynthesis yield of $[^{11}C]$acetate highly dependent on reaction temperature. The best radiosynthesis yield was obtained in reaction of grignard reagent with $[^{11}C]$$CO_2$ at $-10^{\circ}C$. This radiolabeling conditions will be ideal for routine clinical application.