• Journal of the Korean Mathematical Society
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• v.54 no.3
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• pp.967-986
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• 2017

We give the necessary condition for an operator defined on a cartesian product of $c_0(\mathcal{X})$ spaces to be summing or dominated and we show that for the multiplication operators this condition is also sufficient. By using these results, we show that ${\Pi}_s(c_0,{\ldots},c_0;c_0)$ contains a copy of $l_s(l^m_2{\mid}m{\in}\mathbb{N})$ for s > 2 or a copy of $1_s(l^m_1{\mid}{\in}\mathbb{N})$, for any $l{\leq}S$ < ${\infty}$. Also ${\Delta}_{s_1,{\ldots},s_n}(c_0,{\ldots},c_0;c_0)$ contains a copy of $l_{{\upsilon}_n(s_1,{\ldots},s_n)}$ if ${\upsilon}_n(s_1,{\ldots},s_n){\leq}2$ or a copy of $l_{{\upsilon}_n(s_1,{\ldots},s_n)}(l^m_2{\mid}m{\in}\mathbb{N})$ if 2 < ${\upsilon}_n(s_1,{\ldots},s_n)$, where ${\frac{1}{{\upsilon}_n(s_1,{\ldots},s_n})}={\frac{1}{s_1}}+{\cdots}+{\frac{1}{s_n}}$. We find also the necessary and sufficient conditions for bilinear operators induced by some method of summability to be 1-summing or 2-dominated.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.119-120
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• 2013

공구, 다이몰드 등에 널리 쓰이는 TiC, TiN, CrN, TiCrN, TiAlN 코팅의 산화특성을 비교하기 위하여 $600^{\circ}C-900^{\circ}C$에서 대기중 산화시험을 실시하였다. 내산화성은 (TiC, TiN), TiAlN, TiCrN, CrN 코팅의 순서로 증가하였다. 코팅원소중 Ti는 $TiO_2$로, Cr은 $Cr_2O_3$로, Al은 $Al_2O_3$로 산화되었다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1174-1179
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• 2005

Up-flow sludge blanket(USB) reactors were used to investigate the effects of N/C(${NO_3}^--N/COD$) ratio on simultaneous denitrification and methanogenesis processes. Without nitrate feeding, 84% of the influent COD was converted into methane. With the increase of N/C ratio, nitrogen gas increased while methane production decreased and stopped finally at the N/C ratio over 0.20. Influent nitrate was completely denitrified into nitrogen gas while nitrate removal efficiency dropped below 40% at N/C ratio of 0.40 because of deficiency in organic carbon. Fraction of COD utilized by denitrification increased at higher N/C ratios. Methanogenesis started to be effected at N/C ratio of 0.05, which could explain the competition for organic carbon between these microorganisms such as denitrifiers and methanogens, rather than inhibitory effect of nitrate and its intermediates. Critical N/C ratio for simultaneous denitrification and methanogenesis was found to be 0.20. Influent COD was removed over 92% by denitrification, methanogenesis and other biochemical reactions including cell growth at these N/C ratios.

• Ocean and Polar Research
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• v.41 no.2
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• pp.89-97
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• 2019

Long chain plant waxes (n-alkanes, n-alkanoic acids, and n-alcohols) and their carbon isotopic compositions (${\delta}^{13}C$) in geologic archives are valuable tools for paleovegetation reconstruction. However, the sensitivity of different plant wax constituents to vegetation shift is not well understood. This study explores controls on the variation in ${\delta}^{13}C$ values of long-chain n-alkanes ($C_{27}$ to $C_{33}$) and n-alkanoic acids ($C_{26}-C_{30}$) in the Gulf of Mexico core sediments (ODP 625B) near the Mississippi River delta. n-Alkanoic acids' ${\delta}^{13}C$ values were higher than those of n-alkanes by 1-2‰ on average and such a pattern is the opposite from their isotope fractionation observed in living plants: 1-2‰ smaller in n-alkanes than n-alkanoic acids. We attribute this offset to contributions from aquatic plants or microbes that produce high concentrations of $^{13}C-enriched$ long-chain n-alkanoic acids. The sensitivity of n-alkanes and n-alkanoic acids to vegetation and climate varied among chain lengths. The $n-C_{33}$ alkanes were most sensitive to $C_4$ grassland expansion among n-alkane homologues, while no specific trend was observed in n-alkanoic acids. This is due to the similarity in n-alkanoic acid concentrations between $C_3$ and $C_4$ plants by homologues and low terrestrial plant-derived n-alkanoic acid contributions to the sediments. The results of this study suggest that long chain n-alkanoic acids' ${\delta}^{13}C$ values in sediments may be influenced by contributions from different sources such as aquatic plants or microbial inputs and therefore interpretations regarding this matter should be cautiously formulated. We suggest that there is a need for further studies on characterizing long-chain n-alkanoic acids ($C_{26}-C_{34}$) in aquatic plants and microbes from various climates and environments in order to investigate their production and integration into sedimentary archives.

• Advances in environmental research
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• v.3 no.4
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• pp.367-377
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• 2014

In this study, we investigated a life cycle assessment (LCA) of six roof-waterproofing systems [asphalt (C1), synthetic polymer-based sheet (C2), improved asphalt (C3), liquid applied membrane (C4), Metal sheet with asphalt sheet (N1), and liquid applied membrane with asphalt sheet (N2)]for reinforced concrete building using an architectural model. To acquire accurate and realistic LCA results, minimum units of material compositions for life cycle inventory and real data for compositions of waterproofing materials were used. Considering only materials and energy demands for waterproofing systems per square meter, higher greenhouse gas (GHG) emissions could be generated in the order of C1 > N2 > C4 > N1 > C2 > C3 during construction phase. However, the order was changed to C1 > C4 > C3 > N2 > N1 > C2, when the actual architecture model was applied to the roof based on each specifications. When an entire life cycle including construction, maintenance, and deconstruction were considered, the amount of GHG emission was in the order of C4 > C1 > C3 > N2 > C2 > N1. Consequently, N1 was the most environmental-friendly waterproofing system producing the lowest GHG emission. GHG emissions from maintenance phase accounted for 71.4%~78.3% among whole life cycle.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.462-466
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• 2007

Aluminum nitride (AlN) thin films were deposited on Si substrates by using polycrystalline (poly) 3C-SiC buffer layers, in which the AlN film was grown by pulsed reactive magnetron sputtering. Characteristics of grown AlN films were investigated experimentally by means of FE-SEM, X-ray diffraction, and FT-IR, respectively. The columnar structure of AlN thin films was observed by FE-SEM. X-ray diffraction pattern proved that the grown AlN film on 3C-SiC layers had highly (002) orientation with low value of FWHM (${\Theta}=1.3^{\circ}$) in the rocking curve around (002) reflections. These results were shown that almost free residual stress existed in the grown AlN film on 3C-SiC buffer layers from the infrared absorbance spectrum. Therefore, the presented results showed that AlN thin films grown on 3C-SiC buffer layers can be used for various piezoelectric fields and M/NEMS applications.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.345-349
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• 2005

Low resistive ($300{\mu}{\Omega}$-cm) W-C-N films have been deposited on tetraethylorthosilicate (TEOS) interlayer dielectric by atomic layer deposition (ALD) with $WF_6-N_2-CH_4$ gas. The exposure cycles of $N_2$ and $CH_4$ are synchronized with pulse plasma. The W-C-N films on TEOS layer follow the ALD mechanism and keep constant deposition rate of 0.2 nm/cycle from 10 to 100 cycles. As a diffusion barrier for Cu interconnection the W-C-N films maintain amorphous phase and Cu inter-diffusion is not occurred even at $800^{\circ}C$ for 30 min.

• Journal of Ecology and Environment
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• v.43 no.1
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• pp.14-21
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• 2019

Background: Stoichiometry plays an important role in understanding nutrient composition and cycling processes in aquatic ecosystems. Previous studies have considered C:N:P ratios constant for both DOM (dissolved organic matter) and POM (particulate organic matter). In this study, water samples were collected in the six major rivers in Korea and were incubated for 20 days. C:N:P ratios were determined during the time course of the incubations. This allowed us to examine the changes in N and P contents of organic matter during decomposition. Results: POM and DOM showed significant differences in N and P content and the elemental ratios changed during the course of decomposition; DOM showed higher C:N and C:P ratios than POM, and the C:N and C:P ratios increased during decomposition, indicating the preferential mineralization of P over N and N over C. Conclusions: The N and P contents of organic matter in aquatic ecosystem are far from constant and vary significantly during decomposition. More detailed information on the changes in C:N:P ratios will provide improved understanding of decomposition processes and improved modeling of aquatic ecosystems.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.163-170
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• 1988

The MNDO calculations were performed on the various rotamers of N-methyl formamide, N,N-dimethyl formamide, N-methyl acetamide, and N,N-dimethylacetamide in order to investigate the contribution of the one-electron and the steric effect on their rotational barriers about the C-N bond. Results show that while the conformational stabilities of formamides depend mainly on the one-electron factor, those of acetamides depend mainly on the steric factor. According to results obtained by calculations on the rotational barriers about C-N bond, for N-monosubstituted amides the steric effect is larger in the rotational ground state than in the transition state and for N,N-disubstituted amides the steric effect is larger in the rotational transition state.

• Journal of the Korean Chemical Society
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• v.8 no.1
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• pp.20-24
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• 1964

The linear combination of bond orbitals method is used to investigate the reactivity of halomethanes in abstraction reactions by atoms. The activation energy is evaluated on the assumption that, in an activated complex, two electrons in a bond to be broken become completely isolated from the rest of the ${\sigma}$-electron systems. Such a model leads to an intuitively attractive concept that the interactions between the reactive bond and the neighboring bonds govern the reactivity of ${\sigma}$-electron systems. The resulting equation for the activation energy, ${\varepsilon},\;is:\;{\narepsilon}= ${\varepsilon}={\zeta}+$$${\sum}_{i=1}^3$${\eta}c-I,$ c-4 Here, subscript C-4 indicates the bond to be broken, while C-i represents the other three bonds surrounding the reactive bond; ξ is the activation energy of a hypothetical reaction of an isolated C-4 bond and an attacking atom; and ${\eta}$C-i,C-4 stems from the stabilizing interacting of C-4 bond with neighboring C-i bonds. A choie of η′s consistent with bond strength data simplifies the above equation to a form ${\varepsilon}={\zeta}\;+\;N{\eta}c$-H, C-4 where N denotes the number of C-H plus C-F bond in halomethanes. In agreement with this equation, experimental -values increase linearly with increasing N.