• Journal of applied mathematics & informatics
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• v.8 no.2
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• pp.591-611
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• 2001

In this paper, we classify elliptic curve by isomorphism classes over some finite fields. We consider finite field as a quotient ring, saying $\mathbb{Z}[i]/{\pi}\mathbb{Z}[i]$ where $\pi$ is a prime element in $\mathbb{Z}[i]$. Here $\mathbb{Z}[i]$ is the ring of Gaussian integers.

• Journal of applied mathematics & informatics
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• v.8 no.2
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• pp.561-567
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• 2001

In this paper, we investigate the Hyers-Ulam-Rassias stability of a quadratic functional equation f(x+y+z)+f(x-y)+f(y-z)+f(x-z) = 3f(x)+3f(y)+3f(z) and prove the Hyers-Ulam stability of the equation on bounded domains.

• Communications of the Korean Mathematical Society
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• v.12 no.2
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• pp.325-332
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• 1997

Let $Z = X \times Y$ where X and Y are complex manifolds. We suppose that projection $\pi$ on the second factor is a Riemannian submersion, that TX is perpendicular to TY, and that the metrics on Z and on Y are Hermetian; we do not assume Z is a Riemannian product. We study when the pull-back of an eigenfunction of the complex Laplacian on Y is an eigenfunction of the complex Laplacian on Z.

• Journal of the Korean Mathematical Society
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• v.53 no.4
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• pp.847-868
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• 2016

Let M be an invariant subspace of $H^2$ over the bidisk. Associated with M, we have the fringe operator $F^M_z$ on $M{\ominus}{\omega}M$. It is studied the Fredholmness of $F^M_z$ for (generalized) zero based invariant subspaces M. Also ker $F^M_z$ and ker $(F^M_z)^*$ are described.

• Bulletin of the Korean Mathematical Society
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• v.38 no.2
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• pp.325-336
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• 2001

In this paper, we investigate the generalized Hyers-Ulam-Rassias stability of a quadratic function equation f(x+y+z)+f(x-y)+f(y-z)+f(z-x)=3f(x)+3f(y)+3f(z) and prove the Hyers-Ulam-Rassias stability of the equation on bounded domain.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.56-57
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• 2012

본 논문에서는 단상 전류형 qZ-Source 인버터를 개선하여 전압이득이 확장된 단상 전류형 qZ-Source를 제안 한다. 기존의 인버터는 출력전압이 입력전압보다 작거나 같지만 제안한 인버터는 기존의 인버터보다 2배의 출력전압을 가진다. 120 W의 시제품을 제작하여 실험 검증하였다.

• Journal of applied mathematics & informatics
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• v.15 no.1_2
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• pp.377-392
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• 2004

In the present paper, we obtain the Hyers-Ulam-Rassias stability in the sense of Gavruta for the general quadratic functional equation f(χ + y + z) + f(χ - y) + f(χ - z) = f(χ - y - z) + f(χ + y) + f(χ + z).

• Korean journal of applied entomology
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• v.35 no.3
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• pp.193-198
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• 1996

Five species of the genus Zeiraphera from Korea were recognized. Among them species, Z. demutana (Walsingham) and Z. rufumitrana(Herrich-Schaffer), are reported for the first time Korea.

• Communications of the Korean Mathematical Society
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• v.15 no.4
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• pp.597-603
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• 2000

Let K be an algebraically closed filed of characteristic 0 and let G = Z(sub)m x Z(sub)n. We find the conditions under which the elements of the group ring KG are units and idempotents respectively by using the represented matrix. We can see that if $\alpha$ = ∑r(g)g $\in$ KG is an idempotent then r(1) = 0, 1/mn, 2/mn, …, (mn-1)/mn or 1.

• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.351-358
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• 2003

We prove the generalized Hyers-Ulam stability of a quadratic functional equation f($\chi$+ y + z) + f($\chi$) + f(y) + f(z) = f($\chi$+ y) + f(y + z) + f(z + $\chi$) for the functions defined between Banach modules over a Banach algebra.