• Journal of Internet Computing and Services
• /
• v.4 no.4
• /
• pp.65-74
• /
• 2003

Recently, It is required that multimedia data display on not only PC but also the Mobile device such as cellar phone, PDA. Mobile divieces has not sufficient of storage space or main memory and has slow network speed. So we can't process the multimedia data with the existing way on PC. This paper presents various methods for MultimediaPresentation which are able to display on the mobile device with the low-bandwidth and small storage. There Is an analysis that Is playable on the mobile device using presentation area devision method and replayable analysis method. If the display of multimedia presentation is impossible from this analysis, to apply prefetch techniques a using EPOB apoint and as User QoS of multimedia data through prefetch techniques have keep, do so that playable. Then, it is proposed to playable smooth multimedia presentation as that each of the presentations through prefetch Scheduling techniques point and quantity of data which are prefetch.

• The Journal of the Korea Contents Association
• /
• v.5 no.6
• /
• pp.129-137
• /
• 2005

A performance analysis of LEO Satellite Communication Service is being made in a variety of ways. In this paper we examined the variation of interference caused by the distribution of terminals within a cell and the maximum number of users according to the average distance between terminals, which had not been considered in former researches. Also we examined the interference made by sopt beam isolation value of some antennas(tapered-apertured antenna, gaussian antenna) which are used on LEO Satellite Communication Service Assigning this interference to the bandwidth of channels in LEO Satellite Communication Service, and with principal parameters(bandwidth, number of carrier) we made a performance analysis. And comparing tapered-apertured antenna with gaussian antenna we will find out which one is more effective and more suitable for interference.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.10
• /
• pp.773-782
• /
• 2018

A frequency-locked loop(FLL) is a negative-feedback system that uses a frequency detector to improve the phase noise of a voltage-controlled oscillator(VCO). In this work, a theoretical analysis of the phase noise of a VCO in an FLL is presented. The analysis shows that the phase noise of the VCO follows the phase noise determined by the frequency detector and the loop filter within the FLL loop bandwidth, while the phase noise of the VCO appears outside the loop bandwidth. Therefore, it is possible to design an FLL that minimizes the phase noise of the VCO based on the theoretical analysis results. The theoretical phase noise results were verified through experiments.

• Korean Journal of Environment and Ecology
• /
• v.27 no.1
• /
• pp.11-21
• /
• 2013

We tried to find out the core feeding site of the Red-crowned Crane(Grus japonensis) in Cheorwon, Korea by using analysis techniques which are MCP(minimum convex polygon), KDE(kernel density estimation), LoCoH(local nearest-neighbor convex-hull). And, We discussed the difference and meaning of result among analysis methods. We choose the data of utilization distribution from distribution map of Red-crowned Crane in Cheorwon, Korea at $17^{th}$ February 2012. Extent of the distribution area was $140km^2$ by MCP analysis. Extents of core feeding area of the Red-crowned Crane were $33.3km^2$($KDE_{1000m}$), $25.7km^2$($KDE_{CVh}$), $19.7km^2$($KDE_{LSCVh}$), according to the 1000m, CVh, LSCVh in value of bandwidth. Extent, number and shape complexity of the core area has decreased, and size of each core area have decreased as small as the bandwidth size(default:1000m, CVh: 554.6m, LSCVh: 329.9). We would suggest the CVh value in KDE analysis as a proper bandwidth value for the Red-crowned crane's core area zoning. Extent of the distribution range and core area have increased and merged into the large core area as a increasing of k value in LoCoH analysis. Proper value for the selecting core area of Red-crowned Crane's distribution was k=24, and extent of the core area was $18.2km^2$, 16.5% area of total distribution area. Finally, the result of LoCoH analysis, we selected two core area, and number of selected core area was smaller than selected area of KDE analysis. Exact value of bandwidth have not been used in studies using KDE analysis in most articles and presentations of the Korea. As a result, it is needed to clarify the exact using bandwidth value in KDE studies.

• KIPS Transactions on Computer and Communication Systems
• /
• v.9 no.3
• /
• pp.45-58
• /
• 2020

In the current trend of increasing network traffic due to the popularization of cloud service and mobile devices, WAN bandwidth is very low compared to LAN bandwidth. In a WAN environment, a WAN optimizer is needed to overcome performance problems caused by transmission protocol, packet loss, and network bandwidth limitations. In this paper, we analyze the data deduplication algorithm of WANProxy, an open source WAN optimizer, and evaluate its performance in terms of network latency and WAN bandwidth. Also, we evaluate the performance of the two-stage compression method of WANProxy and Zstandard. We propose a new method to improve the performance of WANProxy by revising its data deduplication algorithm and evaluate its performance improvement. We perform experiments using 12 data files of Silesia with a data segment size of 2048 bytes. Experimental results show that the average compression rate by WANProxy is 150.6, and the average network latency reduction rates by WANProxy are 95.2% for a 10 Mbps WAN environment and 60.7% for a 100 Mbps WAN environment, respectively. Compared with WANProxy, the two-stage compression of WANProxy and Zstandard increases the average compression rate by 33%. However, it increases the average network latency by 2.1% for a 10 Mbps WAN environment and 5.27% for a 100 Mbps WAN environment, respectively. Compared with WANProxy, our proposed method increases the average compression rate by 34.8% and reduces the average network latency by 13.8% for a 10 Mbps WAN and 12.9% for a 100 Mbps WAN, respectively. Performance analysis results of WANProxy show that its performance improvement in terms of network latency and WAN bandwidth is excellent in a 10Mbps or less WAN environment while superior in a 100 Mbps WAN environment.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.7
• /
• pp.28-38
• /
• 1997

Previously, we have proposed the M-BECM(Modified-Band Edge Component Maximization), which is a symbol synchronization algorithm based on spectral line method for all-digital high speed digital communications. However, Until now, the characteristics of the timing detector based on the spectral line method including M-BECM was not analyzed, particularly the effect of a timing offset at the optimal convergence pont. In this paper, we analyze the timing dtector's characteristics of the M-BECM and present optimal design value. First, the expression for the timing detector's mean value(often called its S-Curver) as a function of the normalized symbol timing offset is derived. Next, the P $D_{bias}$, the value for compensating the timing offset at an optimal convergence point, and the bandwidth of bandpass filter in the timing detector are calculated. It is also shown and analyzed that the P $D_{bias}$ is affected by varuous factors such as the excess bandwidth of input signal, frequency offsets, noise and particularly, the excess bandwidth of input signal is a major parameter to decide P $D_{bias}$. Finally, analytic resutls are compared to simulation results.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.37 no.10
• /
• pp.37-42
• /
• 2000

There has been a constant effort to study methods for increasing the bandwidth of antenna by microstrip patch. In this paper, we propose a special type of the external rectangular patch, for design and analysis of an antenna using a local multi-point distribution system (LMDS). We minimized electromagnetic emissions from the fringing effect. As a result, we obtained an increase in antenna efficiency and frequency bandwidth. We were also able to design the wide band antenna easily, because of the difference in parameter between the aimed and the simulated antenna was reduced greatly. In comparison with the rectangular patch antenna, the banded one has a wider bandwidth.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.1 s.94
• /
• pp.265-271
• /
• 1999

In the feed drive systems or the spindle systems of machine tools that consist of many mechanical components, a torsional vibration is often generated because of its elastic elements in torque transmission-Generally, the accuracy of motion control system is strongly influenced by the dynamic behavior of coupled transmission components Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So, it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed m1d spindle system. In this paper, based on the DC motor model, a model of electro-drive system with motor has been developed and an optimal criterion for tuning the gain of speed controller is discussed. The frequency bandwidth of the system and the damping ratio in time domain are optimal design specifications for the gain adjustment speed controller. The gains of PI speed controller are then derived from the bandwidth and damping ratio, and those relationships have been classified.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.2
• /
• pp.634-640
• /
• 2015

This paper deals with the design of a microstrip line feed toppled T shaped microstrip patch antenna that gives dualband characteristics at 4 GHz and 6.73 GHz respectively. The simulation of proposed antenna geometry has been performed using method of moment based IE3D simulation software. A radial basis function neural network (RBFNN) is used for the estimation of bandwidth for dualband at 4 GHz and 6.73 GHz respectively. In RBFNN model, antenna parameters such as dielectric constant, height of substrate, and width are used as input and bandwidth of first and second band is considered as output of the network. To validate the RBFNN output, an antenna has been physically fabricated on glass epoxy substrate. The fabricated antenna can be utilized in S and C bands applications. RBFNN results are found in close agreement with simulated and experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.8
• /
• pp.1159-1168
• /
• 1993

The Switched-Capacitor Integrator(SCI) is a basic building block of Switched-Scpacitor Filter(SCF). But owing to the errors from the finite gain and bandwidth of op-amp on SCI, the most of SCP are limited to their applications. Although many of the compensation methods developed for active RC filters can be directly adapted to SCF, this is not true for the analysis of the effects of the op-amp dynamics on the filter response. The effect of finite op-amp gain is similar to the active RC filters. But SCF is more toter-ant of the finite op-amp bandwidth. In this paper, we have considered the errors of the finite gain and bandwidth of op-amp on SCI , and presented the simple and effective methods of compensating the errors of SCI due to the finite op-amp gain using the buffer circuit.