• Kyungpook Mathematical Journal
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• 제48권1호
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• pp.109-121
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• 2008

We determine maximal space-like hypersurfaces which are the images of subbundles of the normal bundle of m-dimensional totally geodesic space-like submanifolds of an (m + 2)-dimensional Lorentzian space form $\tilde{M}_1^{m+2}$(c) under the normal exponential map. Then we construct examples of maximal space-like hypersurfaces of $\tilde{M}_1^{m+2}$(c).

• 대한수학회논문집
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• 제12권3호
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• pp.539-541
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• 1997

Let X be a smooth projective threefold. Let C be a smooth projective curve and let $f : X \to C$ be a fiber space with connected fiber S. Assume that $q_1(S) = 0$. Then we have $-X(O_C)X(O_S) \leq -X(O_X)$.

• 대한수학회논문집
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• 제17권1호
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• pp.57-69
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• 2002

We study a unifying method to obtain nondegenerate isometric immersions of manifolds of constant sectional curvatures c with flat normal bundles into the space forms of curvature c for c= -1,0,1.

• 한국결정학회지
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• 제15권1호
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• pp.9-17
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• 2004

Trigonal system에 屬한 25個 space group들 中 18個는 hexagonal axes만을 나타내는 lattice letter p로 表示되고, 나머지 7個의 rhombohedral space groups R3(146), $R\={3}$(148), R32(155), R3m(160), R3c(161), $R\={3}m$(166), $R\={3}c$(167)은 첫째 3개의 lattice points (0, 0, 0), (2/3, 1/3, 1/3), (1/3, 2/3, 2/3)를 갖는 hexagonal cell in obverse setting과 둘째 primitive rhombohedral cell의 두 가지로 表示된다. 本 論文에서는 space group $R\={3}c$(167)에 대하여 論한 後 이 space group에 屬한 化合物인 tris(1,2,3,4-tetraphenylbuta-1,3-dienyl)cyclotriphosphazene, $C_{84}H_{60}N_3P_3$의 構造를 hexagonal 및 rhombohedral cell 의 양쪽으로 糾明하여 發表하였다.

• Journal of Astronomy and Space Sciences
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• 제24권3호
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• pp.227-234
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• 2007

Sungrazing comet은 근일점이 태양에 매우 가까이 근접하는 혜성을 의미한다. 1996년부터 2007년 4월까지 약 1270여개의 sungrazing comet이 Solar and Heliospheric Observatory(SOHO) 위성에 의해 발견되었다. 현재 이들은 Kreutz, Meyer, Marsden, Kracht 1&2 group으로 나뉘며, 현재 약 85%가 Kreutz group에 속한다. 이 Kreutz group은 근일점이 대체로 태양 표면으로부터 $2{\sim}3R_{\bigodot}$ 떨어진 곳에 위치한다. 우리는 SOHO sungrazing comet의 근일점 분포에 대해 분석하였고, 지금가지 그룹으로 분류되지 못한 혜성 중에서 앞으로 그룹이 될 가능성이 있을 만큼 근일점이 가깝고 궤도가 비슷한 3쌍의 혜성[(C/2000 Y6, C/2000 Y7), (C/2000 V4, C/2001 T5), (C/2003 H6, C/2003 H7)]을 예비그룹으로 제안하고자 한다.

• 대한수학회지
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• 제46권2호
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• pp.327-345
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• 2009

In this paper, we define generalized Fourier-Hermite functionals on a function space $C_{a,b}[0,\;T]$ to obtain a complete orthonormal set in $L_2(C_{a,b}[0,\;T])$ where $C_{a,b}[0,\;T]$ is a very general function space. We then proceed to give a necessary and sufficient condition that a functional F in $L_2(C_{a,b}[0,\;T])$ has a generalized Fourier-Wiener function space transform ${\cal{F}}_{\sqrt{2},i}(F)$ also belonging to $L_2(C_{a,b}[0,\;T])$.

• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.189-200
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• 2015

In this study, we present the results of orbit determination (OD) using satellite laser ranging (SLR) data for the Science and Technology Satellite (STSAT)-2C by a short-arc analysis. For SLR data processing, the NASA/GSFC GEODYN II software with one year (2013/04 - 2014/04) of normal point observations is used. As there is only an extremely small quantity of SLR observations of STSAT-2C and they are sparsely distribution, the selection of the arc length and the estimation intervals for the atmospheric drag coefficients and the empirical acceleration parameters was made on an arc-to-arc basis. For orbit quality assessment, the post-fit residuals of each short-arc and orbit overlaps of arcs are investigated. The OD results show that the weighted root mean square post-fit residuals of short-arcs are less than 1 cm, and the average 1-day orbit overlaps are superior to 50/600/900 m for the radial/cross-track/along-track components. These results demonstrate that OD for STSAT-2C was successfully achieved with cm-level range precision. However its orbit quality did not reach the same level due to the availability of few and sparse measurement conditions. From a mission analysis viewpoint, obtaining the results of OD for STSAT-2C is significant for generating enhanced orbit predictions for more frequent tracking.

• Kyungpook Mathematical Journal
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• 제61권4호
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• pp.889-896
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• 2021

Let 𝜙 be an entire self map on ℂ and let 𝜓 be an entire function on ℂ. A weighted composition operator induced by 𝜙 with weight 𝜓 is given by C_𝜓,𝜙. In this paper we investigate under what conditions the weighted composition operators C_𝜓,𝜙 on the Fock space over ℂ induced by 𝜙 with weight of the form $k_c({\zeta})=e^{{\langle}{\zeta},c{\rangle}-{\frac{{\mid}c{\mid}^2}{2}}}$ is normaloid and essentially normaloid.

• 충청수학회지
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• 제13권1호
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• pp.79-85
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• 2000

In this paper, we have an affirmative solution of G. Godini's open question ([3]): If a normed almost linear space Y is complete, is the normed almost linear space B(X, (Y,C)) complete?

• 대한수학회보
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• 제53권6호
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• pp.1785-1794
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• 2016

This paper gives complete characterization for isometric weighted composition operators on the Fock space of ${\mathbb{C}}^N$. The main result shows that an isometric weighted composition operator on the Fock space of ${\mathbb{C}}^N$ is a unitary operator.