• Korean Journal of Materials Research
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• v.15 no.6
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• pp.426-430
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• 2005

Chemical mechanical polishing (CMP) is an essential process in the production of integrated circuits containing copper interconnects. The effect of alanine in reactive slurries representative of those that might be used in copper CMP was studied with the aim of improving selectivity between copper(Cu) film and tantalum-nitride(TaN) film. We investigated the pH effect of nano-colloidal silica slurry containing alanine through the chemical mechanical polishing test for the 8(inch) blanket wafers as deposited Cu and TaN film, respectively. The copper and tantalum-nitride removal rate decreased with the increase of pH and reaches the neutral at pH 7, then, with the further increase of pH to alkaline, the removal rate rise to increase soddenly. It was found that alkaline slurry has a higher removal rate than acidic and neutral slurries for copper film, but the removal rate of tantalum-nitride does not change much. These tests indicated that alanine may improve the CMP process by controlling the selectivity between Cu and TaN film.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.3
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• pp.194-197
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• 2002

Ion exchange is a chemical reaction between the ions in solution phase and ions in solid phase and is widely used in softening, demineralization, removal and collection of specific ions, and ion migration in the ground water. The ion selectivity depends on the charge and the hydrated radius of ion. The objective of this study was to examine the applicability of anion selectivity obtained from the ion exchange equilibrium OH/sup -/ < F/sup -/ < HCO/sup -/ < Cl/sup -/ < Br/sup -/ ≤ NO₃/sup -/ < SO₄/sup 2-/ to the column ion exchange. The column ion exchange was facilitated in the lower charge of counter-ion in the background electrolyte.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.284-284
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• 2011

Recently, the increasing degree of device integration in the fabrication of Si semiconductor devices, etching processes of nano-scale materials and high aspect-ratio (HAR) structures become more important. Due to this reason, etch selectivity control during etching of HAR contact holes and trenches is very important. In this study, The etch selectivity and etch rate of TEOS oxide layer using ACL (amorphous carbon layer) mask are investigated various process parameters in CH2F2/C4F8/O2/Ar plasma during etching TEOS oxide layer using ArF/BARC/SiOx/ACL multilevel resist (MLR) structures. The deformation and etch characteristics of TEOS oxide layer using ACL hard mask was investigated in a dual-frequency superimposed capacitively coupled plasma (DFS-CCP) etcher by different fHF/ fLF combinations by varying the CH2F2/ C4F8 gas flow ratio plasmas. The etch characteristics were measured by on scanning electron microscopy (SEM) And X-ray photoelectron spectroscopy (XPS) analyses and Fourier transform infrared spectroscopy (FT-IR). A process window for very high selective etching of TEOS oxide using ACL mask could be determined by controlling the process parameters and in turn degree of polymerization. Mechanisms for high etch selectivity will discussed in detail.

• The Journal of the Acoustical Society of Korea
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• v.24 no.8
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• pp.454-461
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• 2005

Time spread due to the multipath in underwater acoustic channel, induces ISI (Inter-Symbol Interference) which degrades the performance of the underwater acoustic communication system. The passive phase conjugation (PPC) which improves the signal to multipath interference ratio (SMR) and therefore reduces the frequency selectivity. is a diversity communication technique giving a less ISI under multipath fading channel. Its frequency selectivity depends on the number of receiver array sensors and time varying source to receiver range. In this study, frequency selectivity of the PPC and its effects on bit error of underwater acoustic communication is analyzed by numerical simulation.

• Membrane Journal
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• v.9 no.2
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• pp.107-113
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• 1999

Alcohol concentration via pervaporation process was performed by using commercial PDMS(polydimethylsiloxane) composite membrane and plasma treated PP(polypropylene) membranes. Effects of operating parameters of pcrvaporation process were examined. With the increase of butanol concentration in the feed, flux and selectivity increased due to the greater affinity of butanol with PDMS than that of water. As the operating temperature increased, free volume as well as the solubilities and diffusivities of alcohol and water increased to result in the greater flux and less selectivity of the membrane. As solubility parameter difference between alcohol and PDMS membrane decreased, high flux and good selectivity were obtained. When PP membrane was plasma treated with methanol, it has 6 times greater flux than PDMS membrane with equivalent separation factor. With the increase of plasma treatment time, flux and selectivity were enhanced. However, excess treatment time caused pore blocking to result in the flux decrease.

• Bulletin of the Korean Chemical Society
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• v.30 no.3
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• pp.599-607
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• 2009

A series of conjugated cyclic and linear enkephalin analogs, Tyr-c[D-A2bu-Gly-Phe-Asp(NH-X)], where X = methyl, stearyl or$ PEG_350$, and Tyr-D-Ala-Gly-Phe-Cys(S-X), where X = methyl, octyl, or farnesyl, were synthesized in solution to investigate the receptor selectivity of opioids based on Schwyzer's membrane compartment $concepts.^{5,6}$ Cyclizations of the target compounds were achieved in high yields (> 60%) employing BOP, $NaHCO_3$ in DMF despite the steric hindrance of the bulky pendant groups. In the binding assay, the hydrophobic fatty acyl conjugates retained $\mu$-receptor selectivity. The unsaturated farnesyl conjugate exhibited the increased binding affinity than the saturated stearyl conjugate for both $\mu$-and $\delta$-opioid receptors. The PEG conjugates displayed the $\delta$-receptor selectivity. The low molecular weight $PEG_350$ conjugate exhibited the increase selectivity than the high molecular weight $PEG_5000$ conjugate to the $\delta$-receptor. The results of this study support the membrane compartment concepts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.248-255
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• 2008

In an OFDMA system the performance of multi-user scheduling in the frequency domain is affected by the frequency selectivity of the channel. If the channel is too flat in the frequency domain, the multi-user scheduling gain might be degraded. On the contrary, if the frequency selectivity is too high and the magnitude of the frequency response severely fluctuates on the allocation bandwidth, it is also hard to get sufficient scheduling gain. For maximizing the multi-user scheduling gain, a cyclic delay diversity technique can be used to adjust the frequency selectivity of the channel. This paper proposes a method to determine the optimal delay value of cyclic delay diversity according to the allocation bandwidth and the channel characteristics.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.108-113
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• 1997

In this paper, the optimum condition of (110) Si etching with the potassium hydroxide(KOH) etchant is presented. Although several researches on (110) Si anisotropic etching have been studied, there has been lack of effects of mask quality and etching conditions on the selectivity and the roughness o the etched surface. Three kinds of masks (film, emulsion and E-beam mask) were used in order to verify the effect of etching properties. Anisotropic bulk etching depends on the crystalline orientation and the concentration and temperature of the etchant. In order to investigate the effect of etching conditions on selectivity and the roughness of the etched surface, the concentration of the etchant was varied from 35 to 45 per cent in weight with increments by 5 per cent and the temperature was changed from 70 to 90$^{\circ}C$ with increments by 10$^{\circ}C$. The combination of the temperature of 70$^{\circ}C$ and the concentration of 40wt.% was found to be the optimum etching condition for high selectivity. Etched surfaces show minimum surfaces show minimum surface roughness at a temperature of 80$^{\circ}C$ and a concentation of 40wt.%. Comb structures with various comb widths were fabricated and the lengths of the combs wree measured with several etching time durations. A micro comb structure 525$\mu\textrm{m}$ high was fabricated for MEMS application.

• Weed & Turfgrass Science
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• v.5 no.4
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• pp.191-195
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• 2016

Tefuryltrione is a new hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor, which has been recently registered for the use for paddy rice, Korea. Dose-response studies were conducted to compare rice safety and weed control efficacy of tefuryltrione against Eleocharis kuroguwai. When rice and E. kuroguwai were applied at a range of doses of tefuryltrione, $GR_{90}$ values (the dose required to inhibit weed growth by 90%) of E. kuroguwai were $82.38-93.39g\;a.i.\;ha^{-1}$ in two independent experiments. The $GR_{10}$ values (the dose required to inhibit rice growth by 10%) of tefuryltrione for rice were $297.77-471.54g\;a.i.\;ha^{-1}$. As a result, the selectivity indices ($GR_{10}$ for $rice/GR_{90}$ for E. kuroguwai) of tefuryltrione were 3.19-5.72. Therefore, these results demonstrate that tefuryltrione has a relatively high selectivity between rice and E. kuroguwai with a high herbicidal activity against E. kuroguwai and a good rice safety.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.3
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• pp.181-189
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• 2019

Discarding juvenile fishes under girth 16 cm nearly equal to inner perimeter of codend mesh size collected by a cover net method in bottom trawl. The body size of the main five species (mackerel, horse mackerel, sea bream, melon seed and black throat seaperch) was measured for their body length, girth, weight, height and width and analyzed size selectivity. Frequency of penetrating fish as retention in a cover net was less than 40% of total number of juvenile discarding fish. The most of body length or girth of five species were significantly different between in the codend and in the cover net. The 50% selection girth in the cover net ranged 8-11 cm were smaller than those in the codend ranged 9-13 cm by the species respectively. The 50% selection body length was significantly related with the ratio of body height (H) by body width (W) both for in the codend or in the cover net while 50% selection girth was not significantly related with H/W. Furthermore 50% selection fish size by fish species between in the codend and in the cover net was not significantly different both in body length or girth. Therefore, the girth selectivity represented possibly as one unique value regarding fish body shape was considered as more useful method for multi-species catch in trawl.