• Title/Summary/Keyword: Hom-set

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HOM AND EXT FUNCTORS OF GENERALIZED INVERSE POLYNOMIAL MODULES

  • Han, Chang-Woo;Park, Sang-Won;Cho, Eun-Ha
    • East Asian mathematical journal
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    • v.16 no.1
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    • pp.111-123
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    • 2000
  • Northcott and McKerrow proved that if R is a left noetherian ring and E is an injective left R-module, then $E[x^{-1}]$ is an injective left R[xl-module. Park generalize Northcott and McKerrow's result so that if R is a left noetherian ring and E is an injective left R-module, then $E[x^{-S}]$ is an injective left $R[x^s]$-module, where S is a submonoid of N(N is the set of all natural numbers). In this paper we show $$Hom_{R[x^S]}(M[x^{-S}],\;N[x^{-S}]){\cong}Hom_R(M,\;N)[[x^S]]$$ and using the above result and this isomorphism, finally we show that $$Ext^i_{R[x^S]}(M[x^{-S}],\;N[x^{-S}]){\cong}Ext^i_R(M,\;N)[[x^S]]$$.

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The Higher-Order-Modulated Slow-Frequency-Hopping Spread-Spectrum System over AWGN under Partial-Band Jamming (부분 대역 재밍 하에서의 가산성 백색 가우시안 잡음 채널에서 고차 변조의 저속 주파수 도약 대역 확산 시스템)

  • Ahn, Hyoungbae;Kim, Chanki;No, Jong-Seon;Park, Jinsoo;Song, Hong-Yeop;Han, Sung Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.1
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    • pp.14-24
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    • 2017
  • In this paper, we propose a new EIM(erasure insertion method) based on the average-minimal-noise-power for HOM(higher order modulation) over AWGN(additive white Gaussian noise) under PBJ(partial-band jamming). Then we design SFH/SS(slow-frequency-hopping spread-spectrum) system by applying this method and formulate the PER(packet error rate) of the system. Based on this formula, we propose a new method to set the optimal threshold of the EIM and verify it at the designed 16-QAM SFH/SS system.

DERIVED LIMITS AND GROUPS OF PURE EXTENSIONS

  • LEE, H.J.;KIM, S.J.;HAN, Y.H.;LEE, W.H.;LEE, D.W.
    • Honam Mathematical Journal
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    • v.21 no.1
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    • pp.157-169
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    • 1999
  • For a k-connected inverse system $({\scr{X}},\;*)=((X_{\lambda},\;*),p_{{\lambda}{{\lambda}}^{\prime}},\;{\Lambda})$ of pointed topological spaces and pointed preserving weak fibrations, inducting epimorphic chain maps, over a directed set, we show that the homotopy group ${\pi}_k(lim{\scr{X}},\;*)$ of the inverse limit is isomorphic to the integral homology group $$H_k(lim{\scr{X}};\mathbb{Z})$. Using the result of S. $Marde{\check{s}}i{\acute{c}}$, we prove that the group of pure extension $Pext(colimH^n({\scr{X}},\;A)$ is isomorphic to the group of extension $Ext({\Delta}({\lambda}),\;Hom(H^n({\scr{X}}),\;A))$.

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DMRUT-MCDS: Discovery Relationships in the Cyber-Physical Integrated Network

  • Lu, Hongliang;Cao, Jiannong;Zhu, Weiping;Jiao, Xianlong;Lv, Shaohe;Wang, Xiaodong
    • Journal of Communications and Networks
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    • v.17 no.6
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    • pp.558-567
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    • 2015
  • In recent years, we have seen a proliferation of mobile-network-enabled smart objects, such as smart-phones and smart-watches, that form a cyber-physical integrated network to connect the cyber and physical worlds through the capabilities of sensing, communicating, and computing. Discovery of the relationship between smart objects is a critical and nontrivial task in cyber-physical integrated network applications. Aiming to find the most stable relationship in the heterogeneous and dynamic cyber-physical network, we propose a distributed and efficient relationship-discovery algorithm, called dynamically maximizing remaining unchanged time with minimum connected dominant set (DMRUT-MCDS) for constructing a backbone with the smallest scale infrastructure. In our proposed algorithm, the impact of the duration of the relationship is considered in order to balance the size and sustain time of the infrastructure. The performance of our algorithm is studied through extensive simulations and the results show that DMRUT-MCDS performs well in different distribution networks.

Corresponding Points Estimation of Motion Images by Orthogonal Function Expansion (직교 함수 전개법에 의한 동영상의 대응점 추출)

  • 김진우;김경태
    • Journal of Korea Multimedia Society
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    • v.3 no.4
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    • pp.380-388
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    • 2000
  • In computing the optical flow, Horn and Schunck's method which is a representative algorithm is based on differentiation. Therefore it is difficult to estimate the velocity for a large displacement by this algorithm. In this paper, we propose a method for estimating nonuniform motion from sequential images which is based on integral brightness constancy constraints. The equations which transform a source image to a target image are expressed as a function of the displacement field. If marginal effects can be neglected, the form of the transformation integral transform or orthogonal expansion can be determined from the expansion coefficients of the two images. The apparent displacement field is then computed iteratively by a projection method which utilities the functional derivatives of the linearized moment equations. We demonstrate that the performance of the orthogonal function transform on the data set of large motion.

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