• Journal of the Korea Society for Simulation
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• v.3 no.1
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• pp.151-165
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• 1994

Broadband network based on the Asynchronous Transfer Mode(ATM) concept are becoming the target technology for the emerging Broadband Integrated Services Digital Network(B-ISDN). Since B-ISDN is very complex and requites a great amount of investment, optimum design and performance analysis of such systems are very important. Simulation can be widely used to analyze and examine the broadband network behavior. However, for the complicated system like broadband networks it is extremely difficult and time-consuming to develop a complete model for simulation. In this paper, an object-oriented modeling approach for the broadband network simulation is presented for the effective and efficient modeling. Object-oriented approaches can provide a good structuring capability for complicated simulation models and facilitate the development of reusable and extensible simulation models. We have developed an object-oriented model which consists of object model and behavior model. In the object mode., the components of the broadband network and both constant bit rate(CBR) and variable bit rate(VBR) traffic types of call level, burst level, and cell level are modeled as object classes. In the behavior model, the dynamic features for each object class are represented using the state transition diagram. It has been shown by illustration that objectoriented modeling is an effective tool for modeling the complicated B-ISDN.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.5
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• pp.605-615
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• 2017

A multi-resonant broadband acoustic transducer with six Tonpilz elements operating at different resonant frequencies in a transducer assembly was fabricated, tested, and analyzed. A compensated transducer, modified by adding series inductance to the developed multi-resonant broadband transducer, was shown to provide improved bandwidth performance with a relatively more uniform frequency response compared with the uncompensated transducer. By controlling the series inductance, flat frequency response characteristics at two frequency bands were obtained over the range 38-52 kHz with 1.1 mH inductance and 50-60 kHz with 0.4 mH inductance. These results suggest that the operating frequency of the developed multi-resonant broadband transducer in a chirp echo sounder can be shifted to a different frequency band that is optimized according to the environment for more effective echo surveys of fishing grounds.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.4
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• pp.141-157
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• 2004

In this paper, we consider broadband satellite systems using MF-TDMA(Multi-Frequency Time Division Multiple Access) scheme. First, we analyze return link, superframe structure, and QoS( Quality of Service) parameters in broadband satellite systems, and mathematically formulate the QoS-based optimal timeslot allocation problem as a nonlinear integer programming problem for broadband satellite systems with clear-sky and rain-fade satellite terminals, and multiple data classes. Next, we modify the proposed problem to solve it within in a fast time, and suggest the QoS-based optimal timeslot allocation scheme. Extensive simulation results show that the proposed scheme finds an optimal solution or a near optimal solution within 5ms at Pentium IV PC.

• Journal of the Optical Society of Korea
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• v.20 no.2
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• pp.263-268
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• 2016

Broadband metal-dielectric-metal terahertz filters composed of complementary rings are designed and demonstrated. Four samples with different parameters were fabricated. Results measured using THz time-domain spectroscopy system show excellent agreement with simulations. Compared with the broadband filters reported before, the complementary ring structure in our design is insensitive to any polarization at normal incidence due to symmetry of the ring. Furthermore, the influence of structure parameters (such as period, radius, slot width, thickness and incidence angles) on the transmission characteristics has been investigated theoretically. The encouraging results afforded by designing of the filters could find applications in broadband sensors, terahertz communication systems, and other emerging terahertz technologies.

• Journal of information and communication convergence engineering
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• v.15 no.2
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• pp.73-78
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• 2017

A general linearly constrained broadband adaptive array is examined in the eigenvector space with respect to the optimal weight vector and the adaptive algorithm. The optimal weight vector and the general adaptive algorithm in the eigenvector space are obtained by eigenvector matrix transformation. Their operations are shown to be the same as in the standard coordinate system except for the relevant transformed vectors and matrices. The nulling performance of the general linearly constrained broadband adaptive array depends on the gain factor such that the constraint plane is shifted perpendicularly to the origin by an increase in the gain factor. The general linearly constrained broadband adaptive array is observed to perform better than a conventional linearly constrained adaptive array in a coherent signal environment, while the former performs similarly to the latter in a non-coherent signal environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.2
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• pp.221-232
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• 2015

Broadband echoes measured in live chub mackerel Scomber japonicus, goldeye rockfish Sebastes thompsoni, and fat greenling Hexagrammos otakii with different morphologies and internal characteristics were analyzed in time and frequency domains to understand the species-specific echo feature characteristics for classifying fish species. The mean echo image for each time-frequency representation dataset obtained as a function of orientation angle was extracted to mitigate the effect of fish orientation on acoustic scattering. The joint time-frequency content of the broadband echo signals was obtained using the smoothed pseudo-Wigner-Ville distribution (SPWVD). The SPWVDs were analyzed for each echo signature of the three fish species. The results show that the time-frequency analysis provided species-specific echo structure patterns and metrics of the broadband acoustic signals to facilitate fish species classification.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.912-916
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• 2004

The home network is the technique to guarantee a safe, economical, socially integrated, and healthy life to the family and it provides domestic safety, instrument control, controllable energy and health monitoring by the connection of the home appliances using wired and wireless networks. A home control system has been developed for managing and controlling home appliances. This paper designs the broadband PLC home controller using broadband PLC technology which can save much cost at a network infrastructure using the existing power line at a home and design the USB home controller using USB technology which is low cost and has many goods with it. And the embedded home server manages those. The CDMA module provides mobile functions to the home control system in this paper. And we choose the OSGi specification which is compatible with other home middleware and can accept various communication techniques of home network

• Journal of Advanced Navigation Technology
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• v.10 no.3
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• pp.213-218
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• 2006

In this paper, we analyzed the performance of orthogonal frequency division multiplexing/ frequency hopping multiple access(OFDM/FHMA) hybrid system that in impulsive interference and broadband wireless communication channel then we applied the turbo code scheme to make satisfied in data and voice transmission service. Also, we compared the bit error rate(BER) performance of turbo coded diversity scheme in the OFDM/FHMA hybrid system. As a result of simulation, proposed OFDM/FHMA hybrid system shows the enhancement of 10 times compared to the general OFDM/FHMA system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6839-6845
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• 2015

The optimization design method for the broadband operation of the sleeve monopole was proposed to unify the multiple antennas essential to the multi-functional broadband wireless communication systems into one antenna. The structure of the sleeve part was optimized to enhance the impedance matching characteristics based on the theoretical analysis that sleeve part can works as the open stub. The thick monopole was used for the broadband operation. The radius of the sleeve and the permittivity of the dielectric inside the sleeve was optimized to enhance the impedance matching characteristics for the broadband operation. The optimized sleeve monopole having thick monopole shows broadband characteristics over 3:1 bandwidth, from 0.8 to 2.43 GHz, which is suitable for the commercial wireless communication system. The proposed broadband sleeve monopole can reduce multiple antennas essential to the multi-functional broadband systems to one antenna.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.880-882
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• 2004

This paper presents the design and simulation results of 7 waveguide dielectric rod array antennas for 7 channel DBF(Digital beamformer) receivers for stratospheric system. A waveguide. dielectric antenna type, which has FTEP(Flat-toped element pattern) to manufacture easily. Also, the calculated element patterns according to the permittivity are compared. The designed antenna will be used for generating multibeam radiation pattern by means DBF.