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181.
Doo-Hee Chang Seung-Ho Jeong Bong-Guen Hong Kyu-Sun Chung Gon-Ho Kim Jae-Shin Lee 《Current Applied Physics》2001,1(6):497
The radial profiles of KT-1 tokamak (major radius of 27 cm, minor radius of 4.25 cm, two poloidal stainless-steel limiters) edge plasma parameters are measured using single and triple electric probes. The particle transport parameters are calculated from the measured edge plasma parameters, and the results are analyzed by the simple fluid approximations. The cross-field particle diffusion coefficient (D) in the boundary plasma of the KT-1 is calculated from the density scrape-off length (λn) measured by using a triple probe. The particle density and electron temperature fall exponentially in the radial direction with the e-folding length of λn=0.13 cm and λe=0.41 cm, respectively. From the scrape-off layer (SOL) model, the experimental values of scrape-off length (λn) is used to calculate the cross-field diffusion coefficient (D=1.2×103cm2/s), roughly corresponding to one third of the typical Bohm value. A simple SOL model with the contribution of recombination is introduced to evaluate the Bohm diffusion in the KT-1 tokamak edge plasma. Cross-field heat conductivity calculated from these deduced values is 5.2D in the SOL of KT-1 edge plasma. These results provide the finally certain information for edge particle transport in the KT-1 boundary plasmas. 相似文献
182.
Sub Hur Hodeok Jang Yonghoon Kim Hanlim Lee Seongtaek Hwang Yunje Oh Y. J. Sung Y. S. Kim Jichai Jeong 《Optical and Quantum Electronics》2007,39(7):561-569
We investigate the performance limits of a pico-cell system using the radio- over-fiber technique with an electroabsorption
modulator (EAM) in a 2.4 GHz wireless local area network (WLAN) environment. To understand the performance limits of the system
using an EAM as the optical transceiver, we vary the optical modulation index (OMI) of the transmitter for different bias
voltages to the EAM. Power margins in the links are found to estimate a possible service range, and packet loss rates (PLRs)
in the pico-cell system are measured to evaluate the transmission performance. The total service range can be extended up
to 3 m by adjusting the OMI of the transmitter for different applied bias voltages to the EAM. 相似文献
183.
Kyung Ah Jeon Hyo Jeong Son Chang Eun Kim Jong Hoon Kim Sang Yeol Lee 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):222
ZnO nanowires were fabricated on c-plane (0 0 0 1), a-plane (1 1 2¯ 0) sapphire, and boron doped p-type (1 0 0) Si substrates in vacuum furnace by simple physical vapor deposition. Room temperature photoluminescence spectra of the nanowires show the near band-edge emission and the deep-level green light emission. The ZnO nanowires formed on sapphire (1 1 2¯ 0) substrates exhibited enhancement on optical properties and better crystalline structures than those of nanowires grown on other substrates. The formation mechanism and the effect of substrate direction on structural and optical properties of the nanowires are discussed. 相似文献
184.
Sangtae Jeong 《Journal of Number Theory》2011,131(6):1089-1104
We revisit hyperderivatives to build on the integral theory of calculus in positive characteristic p. In particular, we give necessary and sufficient conditions for the exactness of a hyperdifferential form associated with hyperderivatives and then propose a closed formula for finding the hyperantiderivative of an exact form. 相似文献
185.
Hong Kyung Choi Jeong Ho Chang Il Hwan Ko Bong Yong Jeong Jung Bae Kim 《Journal of solid state chemistry》2011,184(4):805-2221
This work describes the development of highly efficient human DNA separation with functionalized mesoporous silica (FMS) materials. To demonstrate the electrostatic interaction effect between the target DNA molecules and FMS, three aminofunctionality types comprised of a mono-, a di-, and a tri-amine functional group were introduced on the inner surfaces of mesoporous silica particles. Systematic characterization of the synthesized materials was achieved by solid-state 29Si and 13C-NMR techniques, BET, FT-IR, and XPS. The DNA separation efficiency was explored via the function of the amino-group number, the amount used, and the added NaCl concentration. The DNA adsorption yields were high in terms of the use of triaminofunctionalized FMS at the 10 ng/L level, and the DNA desorption efficiency showed the optimum level at over 3.0 M NaCl concentration. The use of FMS in a DNA separation process provides numerous advantages over the conventional silica-based process. 相似文献
186.
187.
Young-Kwon Park Hyung Won Lee Jong-Ki Jeon Seung-Soo Kim Changkook Ryu Ji Man Kim Ho-Jeong Chae Kwang-Eun Jeong 《Research on Chemical Intermediates》2011,37(9):1283-1291
The catalytic cracking of oil fractions separated from summer food waste leachate was investigated over BEA zeolite and Al-SBA-15 catalysts. In this study, a mixture of food waste oil fractions and catalyst was directly introduced to pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), with the resulting vapor phase products being simultaneously analyzed. Various acid compounds, including oleic acid, produced by the non-catalytic pyrolysis of food waste leachate were reformed into valuable compounds, such as oxygenates, hydrocarbons, and aromatics. The BEA zeolite catalyst showed higher selectivity for hydrocarbon compounds, especially aromatics, within the gasoline range due to its superior cracking ability originating from its highly acidic sites. Conversely, the cracking performance of the Al-SBA-15 catalyst, possessing mild acidic sites, was lower than that of the BEA zeolite. Increasing the amount of Al-SBA-15 catalyst enhanced the cracking activity and resulted in higher selectivity for hydrocarbons. 相似文献
188.
Jeong‐Heui Choi Hae‐Jung Yoon Jung‐Ah Do Yong‐Chun Park Jae Hun Kim Dongmi Choi 《Biomedical chromatography : BMC》2011,25(4):493-497
A residual determination method as a regulatory residue method was developed using HPLC‐UVD for prohexadione residues in Chinese cabbage (Brassica pekinensis) and apple (Malus domestica). The developed method consisted of solid–liquid extraction with acidic acetonitrile and ion‐suppression liquid–liquid partitioning, followed by anion exchange cartridge cleanup. The limits of detection and quantitation for the method were 0.005 and 0.02 mg/kg, respectively. The method gave good linearity in the range of 0.02–2.5 mg/kg. Accuracy and precision ranged from 84.1 to 94.1% and from 2.4 to 6.9%, respectively. Additionally, the confirmative conditions of LC‐MS/MS for prohexadione were set in negative electrospray ionization mode with transitions of m/z 211.4 → 167.5 and m/z 211.4 → 123.5 in the selected reaction monitoring mode. The applicability of the method was demonstrated by analyzing real samples collected from local markets in Seoul, Republic of Korea. This developed method fully deserves consideration in accordance with its sensitivity, accuracy and precision required for residue analysis of prohexadione in Chinese cabbages and apples. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
189.
190.
Sung Joong Lee Semin Park Jin Young Choi Jae‐Han Shim Eun‐Ho Shin Jeong‐Heui Choi Soo Taek Kim A. M. Abd El‐Aty Jong Sung Jin Dong Won Bae Sung Chul Shin 《Biomedical chromatography : BMC》2009,23(7):719-731
It would be preferable for pesticide residues substituted by hydrolyzable functionality to be analyzed after cooking because their structures are apt to degrade during boiling and/or heating. A liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method for the quantitative determination of 44 pesticide residues with hydrolyzable functional group in five typical vegetable widely consumed in Republic of Korea is described. The sample clean‐up was carried out according to the method of Food Code No. 83 established by the Korea Food and Drug Administration (KFDA). Zorbox XDB‐C18 column was selected for the analysis because of the best peak separation. The LC mobile phase consisted of water and 5 mm methanolic ammonium formate, which resulted in a peak shape with good symmetry at each run. Tandem mass spectroscopic (MS/MS) experiments were performed in ESI positive mode and the multiple reaction monitoring modes. A conventional matrix effect was modified to more comprehensive form 100γij (%). A high matrix effect (30%) was detected for the seven polar pesticides, namely thiamethoxam, clothianidin, acetamiprid, aldicarb, thiacloprid, pirimicarb and methabenzthiazuron. The limits of detection were in the range of 0.1–8.1 µg/kg, indicating a good sensitivity. Most of the recoveries ranged from 70 to 131% with RSDs ≤ 20%. The current method allowed rapid quantitation and identification of low pesticide levels in the cooked vegetable samples. Of the screened pesticide residues, only fluquinconazole and dimethomorph below the maximum residue levels established by the KFDA were detected in onion and cucumber samples. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献