• 대한기계학회논문집
• /
• 제19권1호
• /
• pp.212-218
• /
• 1995

Turbulent flow and heat transfer characteristics around staggered tube bundles were studied using a non-orthogonal boundary fitted coordinate system and the low Reynolds .kappa. - .epsilon. turbulence model suggested by Lam and Bremhorst. The predicted flow characteristics for two tube pitches and tube arrangement showed good agreement with the experimental data except the strongly curved region. The predicted Nusselt number was compared with measurements obtained in the staggered rough bundles and it revealed the similar trend to measurements, but the location of the maximum and minimum heat transfer differed somewhat from the measurements.

• Bulletin of the Korean Chemical Society
• /
• 제34권1호
• /
• pp.231-236
• /
• 2013

Some cytotoxicity studies for the interpretation of the interaction between nanoparticles and cells are non-mechanistic and time-consuming. Therefore, non-biological screening methods, which are faster and simpler than in-vivo and in-vitro methods, are required as alternatives to current cytotoxicity tests. Here, we proposed a simple screening method for the analysis of the interaction between several AgNPs (bare-, citrate-, and polyvinylpyrrolidone-coating) and dye-containing vesicles acting as a biomimetic cell-membrane. The interaction between AgNPs and vesicles could be evaluated readily by UV-vis spectra. Absorbance deviation in UV-vis spectra revealed a large attraction between neighboring particles and vesicles. This was confirmed by (Derjagin, Landau, Verwey, and Overbeek) theory and DMF (dark-field microscopy) analysis. This proposed method might be useful for analyzing the cytotoxicity of nanoparticles with cell-membranes instead of in vitro or in vivo cytotoxicity tests.

• 한국안전학회지
• /
• 제3권1호
• /
• pp.15-19
• /
• 1988

The falling ball viscometer has been widely used for measuring the viscosity of the Newtonian fluids because of its simple theory and low cost. The use of the falling ball viscometer for measuring the non-Newtonian viscosity has been of interest to rheologists for some years. The analysis of the experimental results in a falling ball viscometer rest on Stokes law which yields the terminal velocity for a sphere moving through an infinite medium of fluids. An attempt to use the falling ball viscometer to measure the non-Newtonian viscosity in the intermediate shear rate ranEe was sucessfully accomplished by combining the direct experimental obserbations with a simple analytical model for the average shear-stress and shear rate at, the surface of a sphere. In the experiments with highly viscoelastic polyacrylamide solutions the terminal velocity was observed to be dependent on the time interval between the dropping of successive balls. The time-dependent phenomenon was used to determine characteristic diffusion times of the concentrated solutions of polyacrylamide.

• Journal of Information Processing Systems
• /
• 제10권2호
• /
• pp.163-175
• /
• 2014

This paper will focus on improving the performance of orthogonal frequency division multiplexing (OFDM) in Rayleigh fading environments. The proposed technique will use a previously published method that has been shown to improve OFDM performance in independent fading, based on ordered sub-carrier selection. Then, a simple non-iterative method for finding the optimal bit-loading allocation was proposed. It was also based on ordered sub-carrier selection. We compared both of these algorithms to an optimal bit-loading solution to determine their effectiveness in a correlated fading environment. The correlated fading was simulated using the JTC channel models. Our intent was not to create an optimal solution, but to create a low complexity solution that can be used in a wireless environment in which the channel conditions change rapidly and that require a simple algorithm for fast bit loading.

• Bulletin of the Korean Chemical Society
• /
• 제12권6호
• /
• pp.666-673
• /
• 1991

The elongation of the chain length at 2'position of aminothiazolylacetamido group of cephalosporin antibiotics was achieved. The derivatives with elongated side chain at 2'position were successfully synthesis and their in vitro activities were evaluated. It is indicated that there is an optimum range of the chain length in order to exhibit higher biological activities. This result could open a possibility for the development of the cephalosporin antibiotics with higher activities by further variation of the substituents at other positions. The cephalosporin derivatives with a simple (relatively non-functionalized) side chain as well as with a linear extended side chain were also prepared. Low activities of these derivatives led to a conclusion that either simple (non-functionalized) change or linear elongation of the side chain does not enhance the antibacterial activities.

• Kyungpook Mathematical Journal
• /
• 제61권1호
• /
• pp.11-21
• /
• 2021

We study the structure of rings whose factor rings modulo nonzero proper ideals are right duo; such rings are called right FD. We first see that this new ring property is not left-right symmetric. We prove for a non-prime right FD ring R that R is a subdirect product of subdirectly irreducible right FD rings; and that R/N∗(R) is a subdirect product of right duo domains, and R/J(R) is a subdirect product of division rings, where N∗(R) (J(R)) is the prime (Jacobson) radical of R. We study the relation among right FD rings, division rings, commutative rings, right duo rings and simple rings, in relation to matrix rings, polynomial rings and direct products. We prove that if a ring R is right FD and 0 ≠ e2 = e ∈ R then eRe is also right FD, examining that the class of right FD rings is not closed under subrings.

• 대한수학회보
• /
• 제43권3호
• /
• pp.627-634
• /
• 2006

A Weyl type algebra is defined in the book ([4]). A Weyl type non-associative algebra $\={WP_{m,n,s}}$ and its restricted sub-algebra $\={WP_{m,n,s_{\gamma}}}$ are defined in various papers ([1], [12], [3], [11]). Several authors 0nd all the derivations of an associative (Lie or non-associative) algebra in the papers ([1], [2], [12], [4], [6], [11]). We find all the non-associative algebra derivations of the non-associative algebra $\={WP_{0,2,0_B}$, where $B=\{{\partial}_0,\;{\partial}_1,\;{\partial}_2,\;{\partial}_{12},\;{\partial}^2_1,\;{\partial}^2_2\}$.

• 대한수학회논문집
• /
• 제21권1호
• /
• pp.45-52
• /
• 2006

Every non-associative algebra L corresponds to its symmetric semi-Lie algebra $L_{[,]}$ with respect to its commutator. It is an interesting problem whether the equality $Aut{non}(L)=Aut_{semi-Lie}(L)$ holds or not [2], [13]. We find the non-associative algebra automorphism groups $Aut_{non}\; \frac\;{(WN_{0,0,1}_{[0,1,r_1...,r_p])}$ and $Aut_{non-Lie}\; \frac\;{(WN_{0,0,1}_{[0,1,r_1...,r_p])}$ where every automorphism of the automorphism groups is the composition of elementary maps [3], [4], [7], [8], [9], [10], [11]. The results of the paper show that the F-algebra automorphism groups of a polynomial ring and its Laurent extension make easy to find the automorphism groups of the algebras in the paper.

• 호남수학학술지
• /
• 제28권2호
• /
• pp.197-204
• /
• 2006

For the evaluation algebra $F[e^{{\pm}{\chi}}]_M$, if M={$\partial$}, the automorphism group $Aut_{non}$($F[e^{{\pm}{\chi}}]_M$) and $Der_{non}$($F[e^{{\pm}{\chi}}]_M$) of the evaluation algebra $F[e^{{\pm}{\chi}}]_M$ are found in the paper [12]. For M={${\partial}^n$}, we find $Aut_{non}$($F[e^{{\pm}{\chi}}]_M$) and $Der_{non}$($F[e^{{\pm}{\chi}}]_M$) of the evaluation algebra $F[e^{{\pm}{\chi}}]_M$ in this paper. We show that a derivation of some non-associative algebra is not inner.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 추계학술대회 논문집
• /
• pp.297-300
• /
• 2008

In this paper, a simple and computationally efficient approach to non-isothermal three-dimensional analysis of hot forging processes is presented based on rigid-thermoviscoplastic finite element method. In the approach, the temperatures of dies are considered to be constant. Two hot forging processes of large crank shafts ranging from 800 to 1000 kg are simulated using the simple approach.