• Honam Mathematical Journal
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• v.30 no.3
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• pp.487-504
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• 2008

In this paper we study the geometry of codimension 2 screen conformal Einstein half lightiike submanifolds M of a semi-Riemannian manifold $(\={M}(c),\={g})$ of constant curvature c, with a Killing co-screen distribution on $\={M}$. The main result is a classification theorem for screen homothetic Einstein half lightlike submanifold of Lorentzian space forms.

• The Pure and Applied Mathematics
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• v.17 no.1
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• pp.29-38
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• 2010

We study the geometry of half light like submanifold M of a semi-Riemannian space form $\bar{M}$(c) subject to the conditions : (a) the screen distribution on M is totally umbilic in M and the coscreen distribution on M is conformal Killing on $\bar{M}$ or (b) the screen distribution is totally geodesic in M and M is irrotational.

• Bulletin of the Korean Mathematical Society
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• v.49 no.6
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• pp.1163-1178
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• 2012

In this paper, we study the geometry of Einstein half lightlike submanifolds M of a semi-Riemannian space form $\bar{M}(c)$ subject to the conditions: (a) M is screen conformal, and (b) the coscreen distribution of M is a conformal Killing one. The main result is a classification theorem for screen conformal Einstein half lightlike submanifolds of a Lorentzian space form with a conformal Killing coscreen distribution.

• Bulletin of the Korean Mathematical Society
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• v.50 no.3
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• pp.705-717
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• 2013

In this paper, we study the geometry of half lightlike submanifolds M of a semi-Riemannian manifold $\tilde{M}$ with a semi-symmetric non-metric connection subject to the conditions; (1) the characteristic vector field of $\tilde{M}$ is tangent to M, the screen distribution on M is totally umbilical in M and the co-screen distribution on M is conformal Killing, or (2) the screen distribution is integrable and the local lightlike second fundamental form of M is parallel.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1091-1098
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• 2012

This paper describes frequency response and propagation characteristics considering semiconducting screen in distribution cables. In CIGRE WG 21-05, Simplified Approach(SA) and Rigorous Approach(RA) which can revise the permittivity considering semiconducting screen propose for more detailed EMTP model and frequency dependant analysis. In this paper, the frequency dependent characteristics of complex permittivity are variously analysed by cole-cole function of RA. The attenuation, propagation velocity and surge impedance according to frequency range(1 kHz to 500 MHz) and cable length are also analysed by SA and EMTP simulation in distribution cables. The propagation velocity considering semiconducting screen is slower, and it is saturated over the range of 1 MHz. The signal is significantly attenuated as frequency range is high.

• Honam Mathematical Journal
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• v.31 no.1
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• pp.17-23
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• 2009

We study the geometry of screen conformal half lightlike submanifolds of a semi-Riemannian manifod. The main result is a classification theorem for screen conformal half lightlike submanifolds of a semi-Riemannian space form with a Killing co-screen distribution.

• Nuclear Engineering and Technology
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• v.38 no.7
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• pp.675-680
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• 2006

The neutron transmutation doping of silicon (NTD), as a method to produce a high quality semiconductor, utilizes the transmutation of a silicon element into phosphorus by neutron absorption in a silicon single crystal. In this paper, we present the design of a neutron screen for a 6' Si ingot irradiation in the NTD2 hole of HANARO. The goal of the design is to achieve an even flat axial distribution of the resistivity, or $Si^{30}(n,{\gamma})Si^{31}$ reaction rate, in the irradiated Si ingot. We used the MCNP4C code to simulate the neutron screen and to calculate the reaction rate distribution in the Si ingot. The fluctuations in the axial distribution were estimated to be within ${\pm}2.0%$ from the average for the final neutron screen design; thus, they satisfy the customers' requirement for uniform irradiation. On the other hand, we determined the optimal insertion depths of the Si ingots by varying the critical control rod position, which greatly affects the axial flux distribution.

• Journal of Power System Engineering
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• v.19 no.1
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• pp.83-89
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• 2015

A ball strainer screen module, which is used for a condenser tube cleaning system, is a critical mechanical component for maintaining condenser cleanliness. Despite of this importance, not many research have been focused on this module because of its relatively low usage. Employing CFD, this study examines the implication of fluid velocity change and blockage ratio on the ball strainer screen velocity and the static pressure distribution. Through this study, the impact of blockage in the space between ball strainer screen modules is verified. Also, it is found that the ranges of non-dimensional velocity distribution and static pressure distribution decrease as blockage ratio becomes smaller.

• The Pure and Applied Mathematics
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• v.19 no.4
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• pp.327-335
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• 2012

We study half lightlike submanifolds M of semi-Riemannian manifolds $\widetilde{M}$ of quasi-constant curvatures. The main result is a characterization theorem for screen homothetic Einstein half lightlike submanifolds of a Lorentzian manifold of quasi-constant curvature subject to the conditions; (1) the curvature vector field of $\widetilde{M}$ is tangent to M, and (2) the co-screen distribution is a conformal Killing one.

• Communications of the Korean Mathematical Society
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• v.25 no.3
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• pp.443-450
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• 2010

In this paper, we study the geometry of lightlike real hyper-surfaces of an indefinite Kaehler manifold. The main result is a characterization theorem for lightlike real hypersurfaces M of an indefinite complex space form $\bar{M}(c)$ such that the screen distribution is totally umbilic.