• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.4
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• pp.87-93
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• 2006

The black-tailed gull chicks, Larus crassirostris, recognize various adult voice signal base on the simple patterns. We investigated behavior change in black-tailed gull chicks through physical manipulation of mew call. They were playback in four situations differing in physical character: 1) frequency manipulation only, 2) duration manipulation only, 3) call intensity(dB) manipulation only, and 4) call interval manipulation only. We observed occurrence of different response of the chicks, which were categorized into two behaviors(hidden and return behavior). The manipulated frequency, duration, and intensity were directly correlated. The chicks exposed to only manipulated call interval(0.5, 1sec) made significantly more hidden and return behavior. Adult black-tailed gull only increased flight time on manipulated call interval. The results suggest that black-tailed gulls use short call interval for alarm signal. The analysis of alarm signal provides an important on basic study of bird strike.

• Journal of Environmental Science International
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• v.19 no.1
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• pp.61-68
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• 2010

In this study, we analyzed the pulse-duration, pulse-interval and peak-frequency of echolocation call in three species as Rhinolophus ferrumequinum, Pipistrellus abramus, and Myotis macrodactylus. The peak frequency and pulse duration for above mentioned species were 69 kHz, 47 kHz and 49 kHz and $69.39{\pm}8.76\;ms$, $4.95{\pm}0.77\;ms$ and $3.09{\pm}0.48\;ms$ for R. ferrumequinum, P. abramus and M. macrodactylus, respectively. The pulse intervals for R. ferrumequinum, P. abramus and M. macrodactylus were $103.61{\pm}9.05\;ms$, $67.59{\pm}3.47\;ms$ and $66.35{\pm}4.96\;ms$, respectively. The pulse pattern of R. ferrumequinum was setting into a short FM call and linked to long CF call and went through the short FM call again. The pulse pattern of M. macrodactylus was comprised with serial short FM call and the CF call was not checked up in accordance with the spectrogram analysis. The long FM call and short CF call got join together for the P. abramus and the peak frequency was checked up at the pulse ending as CF call.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.1
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• pp.1-21
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• 2015

This paper presents two algorithms based on the Jamshidian equation which is from the Black-Scholes partial differential equation. The first algorithm is for American call options and the second one is for American put options. They compute numerically free boundary and then option price, iteratively, because the free boundary and the option price are coupled implicitly. By the upwind finite-difference scheme, we discretize the Jamshidian equation with respect to asset variable s and set up a linear system whose solution is an approximation to the option value. Using the property that the coefficient matrix of this linear system is an M-matrix, we prove several theorems in order to formulate a bisection method, which generates a sequence of intervals converging to the fixed interval containing the free boundary value with error bound h. These algorithms have the accuracy of O(k + h), where k and h are step sizes of variables t and s, respectively. We prove that they are unconditionally stable. We applied our algorithms for a series of numerical experiments and compared them with other algorithms. Our algorithms are efficient and applicable to options with such constraints as r > d, $r{\leq}d$, long-time or short-time maturity T.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.56-66
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• 2009

In the traditional Server/Client architecture, the client connects to the known servers and gets information through web searching. However, nowadays, diverse internet devices providing services (get) working on internet easily. The update interval of the services or information provided by the devices is relatively short. And also they tend to be both a server and a client. In this situation, the way of the traditional information searching such as web searching is not appropriate. In this paper we propose a service push model, where it pushes its service profiles to all the other network devices by broadcasting them on the network. When a device connects to the network newly, it can get all service profiles in the network and it gets service profiles newly pushed by service providers in prompt. Also it can call any service among the service profiles within itself. We implemented a prototype system for the service push model on the JXTA platform based on P2P network. Also we measured the service profile pushing delay, the service discovery time, and the response time of service execution by running test applications written on the prototype system.