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Papers

Total Posts 55
45

Impact of the Asian monsoon climate on ecosystem carbon and water exchanges

JinKyu Hong, Joon Kim | Global Change Biology 17 (2011)

The monsoon system is an important natural driver of ecosystem carbon and water exchanges in Asia and is being altered by anthropogenic forcings. This system is accompanied by heavy rainfall and typhoons in the main growing season, thus causing alterations of environmental conditions such as rainfall, wind, and temperature; therefore, it acts as a natural disturbance to forests in Asia. Therefore, degradation of ecosystem service by monsoon activity reinforced by anthropogenic factors in a changing climate is of great concern. In this study, we presented observational evidences for the interplay of terrestrial carbon and water dynamics with the Asian monsoon and their implication in ecosystem modeling. We analyzed 3­year eddy­covariance data at a temperate deciduous forest in Korea. We used wavelet power and coherence spectra to investigate the Asian monsoon system and to determine its impact on the ecosystem. During the study period, our analysis showed strong coupling between ecosystem functioning and temporal variations of monsoon climate. Further scrutiny on the model outputs showed that the model did not accurately reproduce the observed plant phenology and thus ecosystem carbon and water exchanges disturbed by monsoon activities. Our findings suggest that under projected climate scenarios, terrestrial carbon sinks in monsoon Asia will decline if the monsoon disturbance will exceed its natural range of variation and if there is no enhancement in the robustness of the ecosystem in this region.

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44

Nonlinear instability of the one-dimensional Vlasov-Yukawa system

S.-Y.Ha; Taeyoung Ha; Chi-Ok Hwang; Ho Lee | Journal of Mathematical Physics 52 (2011)

We discuss the nonlinear instability of some class of stationary solutions to the one-dimensional Vlasov–Yukawa system with a mass parameter m. The Vlasov–Yukawa system corresponds to the short-range correction of the repulsive Vlasov–Poisson system arising from plasma physics. We show that the stationary solutions satisfying the Penrose condition are nonlinearly unstable in small mass regime. In a large mass regime, the massiveness of force carrier particles acts as stabilizer in a finite time interval. We present several numerical results to confirm our analytical results.

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43

확률적 분포 측정 기반의 비정상 SIP 트래픽 탐지

허준(Joon Heo) | 정보과학회논문지 38 (2011)

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42

A remark of P_{I,k} on Elliptic Curves and Application for Manchester Coding

Kim, Dae-Yeoul; Kim, Min-Soo | Honam Mathematical Journal 33 (2011)

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41

Potential Field Based Routing for IPv6 over Low Power WPAN

Sangsu Jung, D. Singh | Communications in Computer and Information Sciences 206 (2011)

Requirements of IPv6 over Low Power WPAN (6LoWPAN) are energy conservation and low protocol complexity. Incorporating the desirable features, potential-field-based routing known as ALFA (autonomous load-balancing field-based any cast routing) achieves autonomous load-balancing and efficient path-length provisioning with little control overhead in a wireless mesh network (WMN), which is a hub-and-spoke type network similarly to 6LoWPAN. In this paper, we provide the protocol architecture of ALFA for 6LoWPAN to consider energy consumption. Distinct from the case of ALFA in a WMN, when the energy level of a sensor node declines to a threshold, the exchange of its potential information holds and its energy shortage is reported to a sink node.

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40

Some Results for the q-Bernoulli, q-Euler numbers and polynomials

Daeyeoul Kim; Min-Soo Kim | Advances in Difference Equations 68 (2011)

The q-analogues of many well known formulas are derived by using several results of q-Bernoulli, q-Euler numbers and polynomials. The q-analogues of ζ-type functions are given by using generating functions of q-Bernoulli, q-Euler numbers and polynomials. Finally, their values at non-positive integers are also been computed. 2010 Mathematics Subject Classification: 11B68; 11S40; 11S80.

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39

Local Stability of the pexiderized Cauchy and Jensen's equations in fuzzy spaces

Abbas NajatIi; Jung Im Kang; Yeol Je Cho | Journal of Inequalities and Applications 78 (2011)

Lex X be a normed space and Y be a Banach fuzzy space. Let D = {(x, y) ∈ X × X : ||x|| + ||y|| ≥ d} where d > 0. We prove that the Pexiderized Jensen functional equation is stable in the fuzzy norm for functions defined on D and taking values in Y. We consider also the Pexiderized Cauchy functional equation. 2000 Mathematics Subject Classification: 39B22; 39B82; 46S10.

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38

Information Theories for time-dependent harmonic oscillator

J. Choi, M. Kim, D. Kim, M. Maamache, S. Menouar, I. Nahm | Annals of Physics 326 (2011)

Information theories for the general time-dependent harmonic oscillator are described on the basis of invariant operator method. We obtained entropic uncertainty relation of the system and discussed whether it is always larger than or equal to the physically allowed minimum value. Shannon information and Fisher information are derived by means of density operator that satisfies Liouville–von Neumann equation and their characteristics are investigated. Shannon information is independent of time, but Fisher information is explicitly dependent on time as the time functions of the Hamiltonian vary. We can regard that the Fisher information is a local measure since its time behavior is largely affected by local arrangements of the density, whilst the Shannon information plays the role of a global measure of the spreading of density. To promote the understanding, our theory is applied to special systems, the so-called quantum oscillator with time-dependent frequency and strongly pulsating mass system.

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37

Effects of periodic stimulation on an overly activated neuronal circuit

Okyu Kwon, Kiwoong Kim, Sungwon Park, Hie-Tae Moon | Physical Review E 84 (2011)

Motivated by therapeutic deep brain stimulation, we carried out a model study on the effects of periodic stimulation on an overly activated neuronal circuit. Our neuronal circuit, modeled as a small-world network of noisy Hodgkin-Huxley neurons, is controlled to undergo the mechanism of coherence resonance to exhibit spontaneous synchronization of neuronal firing. This state of energy burst is then directly modulated by a chain of electric pulses. Our study shows that (i) the stimulation blocks the synchronization by generating traveling waves, (ii) only the pulse with proper frequency can block the synchronization, and (iii) the effects of stimulation are completely reversible. It is also found that the stimulation is effective only when the network maintains fairly good structural regularity.

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36

The m-step competition graphs of doubly partial orders

Boram Park, Jung Yeun Lee, and Suh-Ryung Kim | Applied Mathematics Letters 24 (2011)

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