• Bulletin of the Korean Mathematical Society
• /
• v.49 no.3
• /
• pp.445-454
• /
• 2012

On a closed, connected Riemannian manifold with a K$\ddot{a}$ahler foliation $\mathcal{F}$ of codimension $q$, any transverse Killing $r$-form ($2{\leq}r{\leq}q$) is parallel.

• Honam Mathematical Journal
• /
• v.36 no.4
• /
• pp.731-737
• /
• 2014

In this article, we study the transverse Killing forms with finite global norms on complete foliated Riemannian manifolds.

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

• Journal of the Chungcheong Mathematical Society
• /
• v.24 no.4
• /
• pp.769-781
• /
• 2011

We study the geometry of half lightlike sbmanifolds M of a semi-Riemannian space form $\tilde{M}(c)$ admitting a semi-symmetric metric connection subject to the conditions: (1) The screen distribution S(TM) is totally umbilical (geodesic) and (2) the co-screen distribution $S(TM^{\bot})$ of M is a conformal Killing one.

• Kyungpook Mathematical Journal
• /
• v.31 no.2
• /
• pp.263-268
• /
• 1991

• Bulletin of the Korean Mathematical Society
• /
• v.32 no.1
• /
• pp.25-34
• /
• 1995

S. Tachibana [10] has defined a confornal Killing tensor in a n-dimensional Riemannian manifold M by a skew symmetric tensor $u_[ji}$ satisfying the equation $$ \nabla_k u_{ji} + \nabla_j u_{ki} = 2\rho_i g_{kj} - \rho_j g_{ki} - \rho_k g_{ji}, $$ where $g_{ji}$ is the metric tensor of M, $\nabla$ denotes the covariant derivative with respect to $g_{ji}$ and $\rho_i$ is a associated covector field of $u_{ji}$. In here, a covector field means a 1-form.

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

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

• Industry Promotion Research
• /
• v.9 no.3
• /
• pp.193-203
• /
• 2024

This study analyzes user behavior on YouTube Shorts within snack culture and proposes short-form video production strategies by identifying key value factors. Prior research identified seven characteristics (playfulness, time killing, information provision, social presence, interactivity, escapism, conciseness) and criteria based on the 5W1H principles. Surveys and interviews revealed that key user values are playfulness, time killing, conciseness, and interactivity. Users engage without specific purposes, watch 10-20 consecutive pieces selectively, and use it in comfortable environments. This research provides insights for understanding user behavior and short-form video production strategies.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.4 no.1
• /
• pp.12-16
• /
• 1999

Xenorhabdus nematophilus sp., an insect-pathogenic bacterium, was newly isolated from Korean entomopathogenic nematode of Steinernema carpocapsae, which can be used as a useful bioinsecticide. Primary and secondary form variants of Xenorhabdus nematophilus were observed when cultured in vitro. Primary form variants adsorbed bromothymol blue, while secondary form did not. However, many other characters of two variants were very similar. The variants were all rod-shaped and cell size was highly variable ranging from 0.5 by 2.0 ${\mu}$m to 1.0 by 5.0 ${\mu}$m. Both produced highly toxic substances and killed the insect larva within 20∼38 hr, indicating that insect pathogenicity of Xenorhabdus is not directly associated with its phase variation. In addition, cell-free culture supernatant of Xenorhabdus was sufficient to kill the insect larva by injecting it ito insect hemolymph; however, cell-harboring culture broth was more effective for killing the insect. The use of Xenorhabdus nematophilus may provide a potential alternative to Bacillus thuringiensis (Bt) toxins.