• 한국지능시스템학회논문지
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• 제11권6호
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• pp.563-567
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• 2001

We generalize the widebane P0-weyl symbol (P0WS) and the widebane spreading function (WSF) using the generalized warping function . The new generalized P0WS and WSF are useful for analyzing system and communication channels producing generalized time shifts. We also investigated the relationship between the affine Wey1 symbol(AWS) and the P0WS. By using specific warping functions, we derive new P0WS and WSF as analysis tools for systems and communication channels with non-linear group delary characteristics. The new P0WS preserves specific types of changes imposed on random processes. The new WSF provides a new interpretation of output of system and communication channel as weighted superpositions of non-linear time shifts on the input. It is compared to the conventional method obtaining output of system and communication channel as a convention integration of the input with the impulse response of the system and the communication channel. The convolution integration can be interpreted as weighted superpositions of liner time shifts on the input where the weight is the impulse response of the system and the communication channel. Application examples in analysis and detection demonstrate the advantages of our new results.

• 한국지능시스템학회논문지
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• 제11권7호
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• pp.628-632
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• 2001

We propose time-frequency (TF) tools for analyzing linear time-varying (LTV) systems and nonstationary random processes. Obtained warping the narrowband Weyl symbol (WS) and spreading function (SF), the new TF tools are useful for analyzing LTV systems and random processes characterized by generalized frequency shifts, This new Weyl symbol (WS) is useful in wideband signal analysis. We also propose WS an tools for analyzing systems which produce dispersive frequency shifts on the signal. We obtain these generalized, frequency-shift covariant WS by warping conventional, narrowband WS. Using the new, generalized WS, we provide a formulation for the Weyl correspondence for linear systems with instantaneous of linear signal transformation as weighted superpositions of non-linear frequency shifts on the signal. Application examples in signal and detection demonstrate the advantages of our new results.

• 대한수학회보
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• 제42권1호
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• pp.5-15
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• 2005

The conharmonic transformation is a conformal trans-formation which satisfies a specified differential equation. Such a transformation was defined by Y. Ishii and we have generalized his results. Twisted product space is a generalized warped product space with a warping function defined on a whole space. In this paper, we partially classified the twisted product space and obtain a sufficient condition for a twisted product space to be locally Riemannian products.

• 한국컴퓨터그래픽스학회논문지
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• 제21권5호
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• pp.1-10
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• 2015

본 연구는 가상 조경을 구성하는 다양한 종류의 디지털 잎을 쉽고 직관적으로 제작할 수 있는 저작도구 개발방법을 제안한다. 제안하는 저작도구의 핵심 시스템은 영상 워핑기반의 잎몸 윤곽선 변형 방법, 잎맥의 절차적 모델링 그리고 잎의 색과 명암 등을 표현하기 위한 수리모델기반 시각화 방법으로 구성된다. 우선 잎 영상을 입력으로 받아 잎몸에 대한 윤곽선 정보를 찾고, 특징기반 영상 워핑을 활용하여 다양한 잎몸 형상을 직관적인 구조에서 쉽게 생성할 수 있는 잎몸 변형 방법을 설계한다. 그리고 계산된 잎몸 윤곽선을 기반으로 잎몸 형상에 적합한 자연스러운 잎맥 패턴을 생성하는 일반화된 절차적 모델링 방법을 저작도구에 맞게 구현한다. 마지막으로 약수 함수의 합성 기반의 수리모델을 활용하여 잎의 색, 명암 그리고 시간에 따른 변화를 표현할 수 있는 시각화 기능을 적용한다. 제안한 저작도구를 활용하여 제작된 디지털 잎이 다양한 3차원 디지털 콘텐츠 분야에 활용 가능하도록 텍스쳐 지원 기능을 제공한다.