• Bulletin of the Korean Mathematical Society
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• v.36 no.4
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• pp.629-636
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• 1999

We introduce Lipschitz algebras of differentiable functions of a perfect compact plane set X and extend the definition to Lipschitz algebras of infinitely differentiable functions of X. Then we define the subalgebras generated by polynomials, rational functions, and analytic functions in some neighbourhood of X, and determine the maximal ideal spaces of some of these algebras. We investigate the polynomial and rational approximation problems on certain compact sets X.

• Communications of the Korean Mathematical Society
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• v.12 no.1
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• pp.109-112
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• 1997

In this paper, we study on a classification of hypersurfaces given by tansnormal functions on $R^{n+1}_1$. If M is a level set of a transnormal function on $R^{n+1}_1$, then it is one of a hyperplane, a cylinder around k-plane, a pseudo-sphere and a pseudo-hyperbolic space.

• Bulletin of the Korean Mathematical Society
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• v.52 no.1
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• pp.301-312
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• 2015

In this paper, we study a class of spacelike rotational surfaces in the Minkowski 4-space $\mathbb{E}^4_1$ with meridian curves lying in 2-dimensional spacelike planes and having pointwise 1-type Gauss map. We obtain all such surfaces with pointwise 1-type Gauss map of the first kind. Then we prove that the spacelike rotational surface with flat normal bundle and pointwise 1-type Gauss map of the second kind is an open part of a spacelike 2-plane in $\mathbb{E}^4_1$.

• Journal of the Korean Mathematical Society
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• v.46 no.4
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• pp.701-711
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• 2009

We prove that every non-separable connected metric space can be endowed with a total preorder that is order-isomorphic to a nonrepresentable subset of the lexicographic plane and semicontinuous with respect to the metric topology.

• Bulletin of the Korean Mathematical Society
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• v.57 no.5
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• pp.1195-1204
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• 2020

In this paper we consider the holomorphic curves (or derived holomorphic curves introduced by Toda in [15]) with maximal defect sum in the complex plane. Some well-known theorems on meromorphic functions of finite order with maximal sum of defects are extended to holomorphic curves in projective space.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.111-114
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• 1998

Acoustical holography is one of the powerful methods in sound radiation problems. Just measuring hologram data on a plane, one can calculate whole space physical quantities such as pressure, particle velocity, and sound intensity. However, the use of finite and discrete operations introduce significant errors inevitably. This paper reviews error reduction schemes, and introduces error analysis criteria derived from modal analysis. Finally the effect of window functions is investigated by these criteria.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.129-136
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• 1999

This research proposes an effective analytical methodology for vertical vibration of three dimensional frame structures including slabs. The consideration of slabs, although allows more precise results, requires large amount of computer time and memory space due to the use of plane stress elements. In consideration of these problems, a method to properly manage nodal points and degrees of freedom is proposed based on matrix condensation technique. Also studied is the use of substructure method to obtain fast and reliable results with simple input data when they are applied to conventional building structures.

• Korean Journal of Crystallography
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• v.12 no.1
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• pp.1-4
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• 2001

Single crystals of strontium barium metaborate, Sr/sub 1.36/Ba/sub 1.64/(B₃O/sub 6/)₂, were grown for the first time by the high-temperature-solution-growth technique, and a detailed structure analysis was carried out with the space group R3c. The metaborate (B₃O/sub 6/)/sup 3-/ anion planar groups in the title compound form infinite layers parallel to (001) plane, and Sr and Ba atoms are alternatively placed between the layers and are octahedrally coordinated by six O(2) atoms in the neighbouring anion rings.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.407-411
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• 1992

A method for optimal route planning is presented with the assumption that the overall defended area is known in terms of threat potential function. This approach employes tangent plane to reduce the dimension of the state space for optimal programming problems with a state equality constraint. One-dimensional search algorithm is used to select the optimal route among the extermal fields which are obtained by integrating three differential equations from the initial values. In addition to being useful for the route planning through threat potential area, the trajectory planning will be suitable for general two-dimensional searching problems.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.76.2-76.2
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• 2010

We report the extended far-ultraviolet (FUV) halo of NGC 891 above the galactic plane. The FUV intensity distribution is well described by two exponential components, one with the scale height of ~0.34 kpc and the other of ~2.3 kpc. The extraplanar FUV halo is traceable up to > 5 kpc. The FUV halo is attributable to scattered-off starlight by extraplanar dust. Using Monte-Carlo radiative transfer simulations, the FUV intensity distribution along the minor axis is found to be well modeled with two dust comonents. Its implications are discussed.