• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.155-160
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• 2023

The potential performance benefits of Silicon Carbide(SiC) MOSFETs in high power, high frequency power switching applications have been well established over the past 20 years. In the past few years, SiC MOSFET offerings have been announced by suppliers as die, discrete, module and system level products. In high-voltage SiC vertical devices, major design concerns is the edge termination and cell pitch design Field Limiting Rings(FLR) based structures are commonly used in the edge termination approaches. This study presents a comprehensive analysis of the impact of variation of FLR and JFET region on the performance of a 3.3 kV SiC MOSFET during. The improvement in MOSFET reverse bias by optimizing the field ring design and its influence on the nominal operating performance is evaluated. And, manufacturability of the optimization of the JFET region of the SiC MOSFET was also examined by investigating full-map electrical characteristics.

• 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 the Korean Mathematical Society
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• v.55 no.1
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• pp.131-146
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• 2018

We generate ring class fields of imaginary quadratic fields in terms of the special values of certain eta-quotients, which are related to the relative norms of Siegel-Ramachandra invariants. These give us minimal polynomials with relatively small coefficients from which we are able to solve certain quadratic Diophantine equations concerning non-convenient numbers.

• Bulletin of the Korean Mathematical Society
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• v.57 no.5
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• pp.1231-1240
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• 2020

The asymptotic behavior of graded Betti numbers of powers of homogeneous ideals in a polynomial ring over a field has recently been reviewed. We extend quasi-polynomial behavior of graded Betti numbers of powers of homogenous ideals to ℤ-graded algebra over Noetherian local ring. Furthermore our main result treats the Betti table of filtrations which is finite or integral over the Rees algebra.

• Communications of the Korean Mathematical Society
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• v.11 no.4
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• pp.887-893
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• 1996

Let (R,m) be a Cohen-Macaulay local ring with an infinite residue field and let $J = (a_1, \cdots, a_l)$ be a minimal reduction of an equimultiple ideal I of R. In this paper we shall prove that the following conditions are equivalent: (1) $I^2 = JI$. (2) $gr_I(R)/mgr_I(R)$ is Cohen-Macaulay with minimal multiplicity at its maximal homogeneous ideal N. (3) $N^2 = (a'_1, \cdots, a'_l)N$, where $a'_i$ denotes the images of $a_i$ in I/mI for $i = 1, \cdots, l$.

• Bulletin of the Korean Mathematical Society
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• v.45 no.4
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• pp.709-715
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• 2008

We construct certain ring class fields over an imaginary quadratic field by making use of Shimura's canonical models and extend the result of Chen-Yui ([1] Theorem 3.7.5(2)) to the case where (a, b, N) $\neq$ N or (a/N, N) $\neq$ 1 for a positive integer N > 1.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.679-682
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• 1997

This paper presents finite element analysis algorithm combined with vector hysteresis model for accurate analysis of the hysteresis motor. Magnetization-dependent vector model is adapted to calculate the vector magnetization. That is to say, from the magnitude and direction of the magnetic field intensity, the magnetization of each ring element is computed by the vector model. By comparing the simulation results with the experimental ones, it is found that good results are obtained.

• Journal of the Korean Mathematical Society
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• v.37 no.4
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• pp.521-530
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• 2000

We find the values of numerical invariants col(R) and row (R) for R=k[te, te+1, t(e-1)e-1] where k is a field and e$\geq$4. We also show that col(R) = crs (R) and row (R) = drs(R), but they are strictly less than the reduction number of R plus 1.

• Journal of Integrative Natural Science
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• v.6 no.4
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• pp.187-192
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• 2013

We provide a complete proof that the existence of a system of parameters, which is a reduction of the maximal ideal, is essential in Koh-Lee's conjecture.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.641-643
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• 2002

Synchronous generator needs slip-ring and brush for supplying current to rotor with external source. but slip-ring and brush have some problems to supply DC power to field winding with friction and high power loss due to brush voltage drop at high field current. Thus synchronous generator have been designed to brushless machine. Brushless synchronous machines of using permanent halbach array can composed without back core and coreloss. In this paper, analyse on the characteristics of external rotor type permenant magnet brushless with halbach array.