• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.679-685
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• 2002

Low-frequency mono-static reverberation model for shallow-water environment is presented. It is necessary to develop the transmission loss model to calculate the sub-bottom interaction because the ray-based transmission loss model is difficult to compute the pressure accurately which penetrates the bottom medium. In this paper reverberation level is calculated using the RAM (Range dependent Acoustic Model) to augment the multi-path expansion model because it does not estimate transmission loss accurately in shallow water. The signals generated by the L-HYREV and the GSM are compared with the observed signals and it is showed that the L-HYREV model provides a closer fit to the observed signals than those obtained using the GSM.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.133-141
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• 2005

In this paper, we designed about OFDM/QPSK image transmission system simulator embedded watermark in wireless channel environment. Channel environment used OFDM/QPSK still image transmission system considering AWGN, Multi-path fading. And, we analyzed effect of still image and watermark information in considered channel environment. Watermark information is coded by DM-SS (Direct Matric/Spread Spectrum) image watermarking scheme, Also, we used interleaving scheme for mitigating the degradation in watermarking data under wireless channel. As a results, we could know that PSNR of watermark image improved of about 1dB by 54.2371dB then apply interleaving in same multi-path fading environment.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.153-158
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• 2005

In this paper, an improved detection method is Proposed by supplementing multi-path gain for a MMSE detecter. This method is Proposed to complement the shortcomings of the conventional detection method which is used for multiuser detection in STBC CDMA system. We analyzed the improved method in bit error Probability viewpoint and compared the result with that of the conventional method In this result, we showed that the improved method obtains better performance of bit error probability than the conventional method when parameters such as delay, number of user and SNR are increased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.601-609
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• 2002

In multi-path wireless channels with time-variant delay profile, a mobile station measures the received signal strength and report it to network which performs network control function such as handover. In order to improve the maximum ratio combining (MRC) gain, it also should search the strongest signal paths and measure their time offsets fast and exactly. This paper proposes some methods of fast and exactly measuring the multi-path signal strength and time offset. Since the W-CDMA system adopts antenna diversity technique for the next generation high speed packet access (HSDPA) service, we derive the optimum design parameter values for the proposed methods through computer simulations under the HSDPA conditions o( low speed of mobile, of no power control, and of multi-path wireless environment with transmit and receive antenna diversity. Finally, we prove the validity of the proposed methods by showing the improvement of the bit error rate (BER) performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.8
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• pp.856-866
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• 1992

In this paper, the graphic simulation system Is presented which supports the determination of efficient multi-robot motions during cooperation. For the construction of the simulation software for multi robot motions, two problems are described. First problem is that all the robot motions must be determined using both the desired object motions and the holonomic constraints with the object. To find the robot motions combined with the various object motion path, the robot motions are derived from the desired object path instead of a master robot path. There ore, robot motions can be easily modifiable with #he various object motions. This type of motion determination Is different from that of the master-slaves method using the master robot motions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.41-42
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• 2012

• Communications of the Korean Mathematical Society
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• v.29 no.1
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• pp.213-218
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• 2014

J. Malkevitch defined the coded path in r-valent polytopal graphs of uniform face structure and showed many interesting properties of the coded paths. In this paper, we study the simplicity of coded paths in an m-valent planar multigraph which is not a polytopal graph.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.45-51
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• 2000

In this Paper a basic technique of gantry robot control system has been developed to weld the curved part of a large structure. A welding robot is designed to rotate torch and make the torch angle normal to the welding surface. The Kalman filter is applied to obtain the smooth welding path signal from the noised Sensing data. A welding path finding algorithm has been developed in Turbo-C language.

• International Journal of Control, Automation, and Systems
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• v.4 no.1
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• pp.77-86
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• 2006

A new method in robot path generation is presented using an analysis of the characteristics of multi-robot collision avoidance. The research is based on the concept of the collision map, where the collision between two robots is presented by a collision region and a crossing curve TLVSTC (traveled length versus servo time curve). Analytic collision avoidance is considered by translating the collision region in the collision map. The 4 different translations of collision regions correspond to the 4 parallel movements of the actual original robot path in the real world. This analysis is applied to path modifications where the analysis of collision characteristics is crucial and the resultant path for collision avoidance is generated. Also, the correlations between the translations of the collision region and robot paths are clarified by analyzing the collision/non-collision areas. The influence of the changes of robot velocity is investigated analytically in view of collision avoidance as an example.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.160-163
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• 2021

In this paper, we present a path search scheme for the safe movement of the swarm of unmanned systems in unknown dangerous areas. Some of the swarm searches for the primary and secondary paths before the majority of swarm move through dangerous areas. In terms of rapid movement from the dangerous area and preparation for an accident, the primary path is searched first in the destination's direction. The secondary path is searched by considering the distance between the paths to guarantee a safe distance. The computer simulations show that the proposed scheme is suitable for the swarm of unmanned systems.