• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.751-756
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• 2000

Based on Experimental analysis, the characteristics of back pressure in automotive exhaust system is tested for 4-stroke gasoline engine. The back pressure in automotive exhaust system is generated by resistance working of exhaust system, i.e. exhaust manifold, pipe length, pipe banding, difference system pressure with atmospheric pressure. This paper contains experimental results which are tested for the change of exhaust pipe length and torque change are tested under experimental conditions.

• Journal of applied mathematics & informatics
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• 제36권3_4호
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• pp.237-244
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• 2018

Let ${\mathcal{H}}$ be an infinite dimensional separable Hilbert space with a fixed orthonormal base $\{e_1,e_2,{\cdots}\}$. Let L be the subspace lattice generated by the subspaces $\{[e_1],[e_1,e_2],[e_1,e_2,e_3],{\cdots}\}$ and let $Alg{\mathcal{L}}$ be the algebra of bounded operators which leave invariant all projections in ${\mathcal{L}}$. Let p and q be natural numbers (p < q). Let ${\mathcal{A}}$ be a linear manifold in $Alg{\mathcal{L}}$ such that $T_{(p,q)}=0$ for all T in ${\mathcal{A}}$. If ${\mathcal{A}}$ is a Lie ideal, then $T_{(p,p)}=T_{(p+1,p+1)}={\cdots}=T_{(q,q)}$ and $T_{(i,j)}=0$, $p{\eqslantless}i{\eqslantless}q$ and i < $j{\eqslantless}q$ for all T in ${\mathcal{A}}$.

• 대한수학회보
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• 제31권2호
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• pp.215-236
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• 1994

The purpose of the present paper is to study generic submanifolds of a Sasakian space form with nonvanishing parallel mean curvature vector field such that the shape operator in the direction of the mean curvature vector field commutes with the structure tensor field induced on the submanifold. In .cint. 1 we state general formulas on generic submanifolds of a Sasakian manifold, especially those of a Sasakian space form. .cint.2 is devoted to the study a generic submanifold of a Sasakian manifold, which is not tangent to the structure vector. In .cint.3 we investigate generic submanifolds, not tangent to the structure vector, of a Sasakian space form with nonvanishing parallel mean curvature vactor field. In .cint.4 we discuss generic submanifolds tangent to the structure vector of a Sasakian space form and compute the restricted Laplacian for the shape operator in the direction of the mean curvature vector field. As a applications of these, in the last .cint.5 we prove our main results.

• 대한수학회보
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• 제48권1호
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• pp.129-140
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• 2011

The aim of this paper is to study the structure of the fundamental group of a closed oriented Riemannian manifold with positive scalar curvature. To be more precise, let M be a closed oriented Riemannian manifold of dimension n (4 $\leq$ n $\leq$ 7) with positive scalar curvature and non-trivial first Betti number, and let be $\alpha$ non-trivial codimension one homology class in $H_{n-1}$(M;$\mathbb{R}$). Then it is known as in [8] that there exists a closed embedded hypersurface $N_{\alpha}$ of M representing $\alpha$ of minimum volume, compared with all other closed hypersurfaces in the homology class. Our main result is to show that the fundamental group ${\pi}_1(N_{\alpha})$ is always virtually free. In particular, this gives rise to a new obstruction to the existence of a metric of positive scalar curvature.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.57-63
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• 2005

The effects of an urea injection at the exhaust pipe for a 4-cylinder DI(Direct Injection) diesel engine were investigated with the parameters such as urea-SCR(Selective Catalytic Reduction) and EGR system. The urea quantity was controlled by NOx quantity and MAF(Manifold Air Flow). The urea injection quantity can be controlled with the urea syringe pump, precisely. The effects of NOx reduction for the urea-SCR system were investigated with and without ECR engine, respectively. It was concluded that the SUF(Stoichiometric Urea Flow) is calculated and the NOx results are visualized with engine speed and load. Furthermore, the NOx map is made from this experimental results. It was suggested, therefore, that NOx reduction effects of the urea-SCR system without the EGR engine were better than that with the EGR engine except of low load and low speed.

• 한국자동차공학회논문집
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• 제4권1호
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• pp.218-228
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• 1996

The behaviors of the mixture at the downstream of throttle valve in a TBI type gasoline engine plays a greater role in design of intake system. A good mixture has been influencing directly not only on the engine power but also on the pollutant emission. The mixture flow in an intake manifold is very complex, and the flow characteristics are varied with the valve type, valve angle, inlet air flow rate, and the other flow factors. Three kinds of valve are chosen in this study, and the informations of the mixture flow are observed experimentally using a PIV apparatus. Perforate valve has a smaller recirculation zone than the case of solid valve with a lower valve loss coefficient, and iti is verified that the perforated valve is also suitable to control the flow rate in a mixture flow system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2280-2285
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• 2008

A general flow distribution model and a simple process of numerical analysis, which can be applied to multi-pass systems with manifolds, are presented. Correlations are derived from the discrete model, and numerically calculated using a modified equal pressure method. The predicted pressure distribution agrees well with the available experimental results of other researchers with the average error less than 2% for 10 branch manifolds, and 4% for 20 branch manifolds. A parametric study is performed to demonstrate the effect on the flow distribution.

• Bulletin of the Korean Chemical Society
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• 제20권11호
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• pp.1263-1268
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• 1999

The fluorescence properties and photoisomerization behavior of 1-(9-anthryl)-2-(2-quinolinyl)ethene (2-AQE) have been investigated in various solvents. Instead of phenyl ring in 1-(9-anthryl)-2-phenylethene, the intro-duction of quinoline ring reduces not only the fluorescence yield but also the photoisomerization yield, due to competition of efficient radiationless deactivation and an increase in the torsional barrier for twisting in the singlet manifold. The S1 decay parameters were found to be solvent-dependent due to the charge-transfer character of lowest S1 state. Polar solvents reduce the activation barrier to twisting, thus slight enhancing the isomerization of t-2-AQE in the singlet manifold. As solvent polarity is increased, Φf of c-2-AQE is greatly reduced, but Φc →ｔ is practically independent of solvent polarity. Dual fluorescence in t-2-AQE was observed and two fluorescing species could be assigned t-2-AQE and c-2-AQE, where the ratio between two species was dependent on the solvent polarity. Interestingly, in the concentration above 1×10 -4 M, the shapes of the fluorescence excitation spectra of t- and c-2-AQE are significantly altered without spectral changes of their fluorescence and absorption, probably due to the formation of excimer.

• Journal of applied mathematics & informatics
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• 제40권3_4호
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• pp.475-490
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• 2022

The main purpose of the present paper is to introduce a brief analysis on some properties of quasi hemi-slant submanifolds of Kenmotsu manifolds. After discussing the introduction and some preliminaries about the Kenmotsu manifold, we worked out some important results in the direction of integrability of the distributions of quasi hemi-slant submanifolds of Kenmotsu manifolds. Afterward, we investigate the conditions for quasi hemi-slant submanifolds of a Kenmotsu manifold to be totally geodesic and later we provide some non-trivial examples to validate the existence of such submanifolds.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1623-1628
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• 2004

In the 3-dimensional cyclic Lotka-Volterra equations, we show the solution on the invariant hyperplane. In addition, we show the existence of the invariant hyperplane by the center manifold theorem under the some conditions. With this result, we can lead the hyperplane of the n-dimensional cyclic Lotka-Volterra equaions. In other section, we study the 3- or 4-dimensional Hamiltonian Lotka-Volterra equations which satisfy the Jacobi identity. We analyze the solution of the Hamiltonian Lotka- Volterra equations with the functions called the split Liapunov functions by [4], [5] since they provide the Liapunov functions for each region separated by the invariant hyperplane. In the cyclic Lotka-Volterra equations, the role of the Liapunov functions is the same in the odd and even dimension. However, in the Hamiltonian Lotka-Volterra equations, we can show the difference of the role of the Liapunov function between the odd and the even dimension by the numerical calculation. In this paper, we regard the invariant hyperplane as the important item to analyze the motion of Lotka-Volterra equations and occur the chaotic orbit. Furtheremore, an example of the asymptoticaly stable and stable solution of the 3-dimensional cyclic Lotka-Volterra equations, 3- and 4-dimensional Hamiltonian equations are shown.