• 대한수학회보
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• 제60권4호
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• pp.1035-1059
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• 2023

Let p be an odd prime. Let E be an elliptic curve defined over a quadratic imaginary field, where p splits completely. Suppose E has supersingular reduction at primes above p. Under appropriate hypotheses, we extend the results of [17] to ℤ²_p-extensions. We define and study the fine double-signed residual Selmer groups in these settings. We prove that for two residually isomorphic elliptic curves, the vanishing of the signed 𝜇-invariants of one elliptic curve implies the vanishing of the signed 𝜇-invariants of the other. Finally, we show that the Pontryagin dual of the Selmer group and the double-signed Selmer groups have no non-trivial pseudo-null submodules for these extensions.

• 대한기계학회논문집
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• 제17권12호
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• pp.3105-3114
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• 1993

previously, several basic studies in the experimental analysis of stress intensity factors of cracks by slab analogy have been presented by authors. But, for the application of above mentioned method to the analysis of the arbitrarily distributed cracks, there still is several bottlenecks to be overcome in terms of its experimental process and data treatment. Moreover, authors recently proposed an improved experimental method to use the fixed slab analogy device which has promised more accurate measurement of S.I.F. of small cracks. In this paper, for the completion of slab analogy analysis of distributed cracks, a grating imaginary rotation method is introduced. And, to prove its validity, this combined method is applied to the determination of stress intensity factors of theoretically known distributed cracks. The results show good agreement with the existing theoretical solutions and physical crack propagation tendencies.

• 대한전자공학회논문지SD
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• 제37권9호
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• pp.66-77
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• 2000

이 논문에서는 Best Imaginary Level-Iterative(BILI) 분할 방법이라 부르는 새로운 하드웨어/소프트웨어 분할 알고리즘을 제안하다. 이 분할 알고리즘은 여러 개의 하드웨어와 소프트웨어로 이루어진 시스템에 대해서 분할을 할 수 있을 뿐만 아니라, 여러 가지의 구현 가능성 중에서 적은 비용의 구현을 선택하는 문제까지 해결한다. 이 분할 알고리즘은 기존의 분할 알고리즘인 GCLP와 비교하여 약 15%의 비용 감소를 가지고, 항상 최적의 해를 찾는 장수 선형 프로그래밍과 비교하여 약 5%정도의 비용 증가를 가진다.

• 공학논문집
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• 제8권1호
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• pp.51-57
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• 2006

We propose efficient methods for implementing 3-D reconstruction algorithms for Compton camera. Since reconstructing Compton scattered data involves the surface integral over the cone associated with the measurement bin, it is crucial to develop a computationally efficient surface integration method. In this work we assume that a cone is made up of a series of ellipses (or circles) stacked up one o top of the other. In order to reduce computational burden for tracing ellipses formed by the intersection of a cone and an image plane, we construct a series of imaginary planes perpendicular to the cone axis so that each plane contains a circle, not an ellipse. In this case the surface integral can be performed by adding uniform samples along each circle. The experimental results demonstrate that our method using imaginary planes significantly improves computational efficiency while keeping reconstruction accuracy.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1042-1045
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• 1999

This paper presents a new method for contingency selection of the transient stability. Contingency ranking in transient stability is done by estimating the change in the imaginary part of electro-mechanical oscillation mode, which represents modal synchronizing coefficient. And the change in the imaginary part is obtained by applying eigen-sensitivity theory of augmented matrix to linear system model. The Proposed algorithm was tested for New England System and compared the results with PSS/E dynamic simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.118-120
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• 2001

This paper presents a distance relaying algorithm based on the Discrete Fourier Transform(DFT) for elimination of DC-Offset. When the DFT is applied to current signal. the real and imaginary parts of fundamental component consist of fundamental component itself and DC-Offset. The DC-Offset is calculated by four consecutive values of the imaginary components, so that the fundamental component can be accurately estimated. Performance evaluation is presented for A-phase ground faults on 154kV 80km overhead transmission line. The proposed algorithm is inspected by software simulation and hardware simulation.

• 대한수학회보
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• 제53권1호
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• pp.21-28
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• 2016

It is known that no two of the roots of the polynomial equation (1) $$\prod\limits_{l=1}^{n}(x-r_l)+\prod\limits_{l=1}^{n}(x+r_l)=0$$, where 0 < $r_1{\leq}r_2{\leq}{\cdots}{\leq}r_n$, can be equal and all of its roots lie on the imaginary axis. In this paper we show that for 0 < h < $r_k$, the roots of $$(x-r_k+h)\prod\limits_{{l=1}\\{l{\neq}k}}^{n}(x-r_l)+(x+r_k-h)\prod\limits_{{l=1}\\{l{\neq}k}}^{n}(x+r_l)=0$$ and the roots of (1) in the upper half-plane lie alternatively on the imaginary axis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 학술대회 논문집 전문대학교육위원
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• pp.141-145
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• 2007

Using the New Fast Walsh Transform algorithm, we present a new algorithm which reduces the computational amount, and it can consequently calculate the real and imaginary components for current and voltage signals of power system in sampling intervals. The calculation amount is reduced to 2X(m-1) at m samples to measure full harmonics using developed algorithm. When in single harmonic measuring, it needs only 2(log2N-1)+1 additions and subtractions. We developed hardware device for testing, and tested the developed algorithm by measuring real and imaginary components.

• 한국전기전자재료학회논문지
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• 제24권9호
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• pp.744-749
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• 2011

Recently, annual usage of energy is dramatically increasing because industrialization is going faster and more electricity is needed due to various electronic devices. This study focused on the performance characteristics of solar cell using the impedance technique. The experiment measured an impedance according to frequency's from 2 mHz until 1 MHz. It could know that the impedance was decreased according to the frequency increases in solar cell. The imaginary part was changed from capacitance component to inductance component.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.88-88
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• 2002

Satellite Image archiving system requires large storage and long transmission time. A simple and cheap way of overcoming these limitations is to increase the compression ratio. However this requires a feasibility study for accurate applications. Here, a new still image compression standard is being developed, the JPEG2000. It provides lossless and lossy compression, progressive transmission by pixel accuracy and by resolution, region-of-interest coding, user-defined tiling size, random codestream access and processing etc. In this study, we will briefly introduce the JPEG2000 compression standard which provides a new compression technique based on the wavelet technology and offers better compression ratios, and evaluate the compression ratios of JPEG2000 for satellite image by performing various image quality tests. Also, we will compare brief test result using the commercial remote sensing software.