• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.395-402
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• 2003

The capacity of a CDMA cellular system is determined by the amount of interference, therefore the exact estimation of interference is important to evaluate the system performance. In this paper, we propose an approximated equation which calculates reverse link other cell interference in the CDMA cellular systems. The equation using Riemann-Zeta function has a property that it is useful in case of any radio propagation loss exponents. And we compare calculation results with simulation results in other to verify it's usefulness. The upper bound of system capacity calculated with the proposed approximated equation gives almost alike result with the simulation. The proposed interference bound is useful to calculate system capacity and to evaluate some algorithm in a hierarchical cellular system which must be considered various propagation exponents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1828-1835
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• 2000

In this paper, we analyzed the other-cell interference characteristics for various non-uniform traffic distributions and their effects on the capacity of multi-cell CDMA system. We consider three different traffic distributions, i.e., linear, exponential and Gaussian traffic distribution with distribution parameters. Changing the distribution parameter, we can obtain the center-focused distributions or uniform distributions for each model. From the results of other-cell interference calculation we can see that the other-cell interference decreases, as the user concentrates on the base station. Also using frequency reuse efficiency indicating the capacity reduction of a multi-cell system when compared to a single cell system, we evaluate the effect of traffic distribution on the reverse link CDMA capacity. For linear case, the capacity of multi-cell system is reduced to 0.637∼0.867 times that of single cell system. On the other hand, for both exponential and Gaussian cases, the capacity under a multi-cell environment is equal to 70∼100% of that under a single cell. Therefore, we conclude that the average capacity of multi-cell CDMA system are increased when users are likely to be at near the cell base station due to reduced total other-cell interference and decreased when users exist at near the cell edge regardless of traffic distribution models.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1671-1679
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• 2009

The existing subjects of supply chain management, which link business firms to customers, have focused on forward logistics such as acquisition of low and subsidiary parts, manufacturing, distribution and sales. Consequently, it is emphasized that supply chain management has to be a sustainable business activity. Nevertheless, capabilities of reverse supply chain management for domestic companies are still relatively limited compared to advanced foreign companies. For this reason, this study aims to develop the service platform, which provides information on return, retrieval, abolish and recycling using RFID, includes information on packing, placement, loading and unloading and transportation of the goods. In order to achieve the purpose of this study, the research previous studies and analyze achieved diverse cases on reverse logistics, review the present state, and propose service platform application to manage reverse supply chain which will be applied.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.291-297
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• 2002

Due to the increasing demand for high data multimedia service, there has been progressing study of adaptive smart antenna to increase both the performance and capacity using limited wireless resource. IS-95 scheme in the origin of cdma2000 of IMT-2000 standard uses signals of spreading and Walsh-Orthogonal Modulation in reverse link. But, in the case of reverse lint there exists difficulty in synchronous of signals transmitted from users. Therefore, orthogonality between users is not satisfied. So, asynchronous MC-CDMA scheme may yield low performance. In this paper, MC/DS-CDMA scheme to reverse link transmission in adaptive array antenna environment is proposed for spreading the S/P-converted data streams using a given spreading code. Due to frequency diversity effect, simulation results show that the proposed system provides improved BER performance and narrow band interference supple psi on.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.603-608
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• 2007

In the conventional AOA(angle-of-arrival) positioning utilizing reverse-link wireless channel, each sensor should be equipped with an array antenna to measure the incident angle of signal transmitting from a tag. To perform the complicated signal processing for angle measurements, sensor size and its power consumption will be large. In some applications like mobile robot location, there exists no strict restriction in tag size or in power consumption. Rather, it is desirable that the sensor would be as small as possible. This paper presents a new AOA positioning method utilizing forward-link channel. Under the assumption that the mobile robot is operating on the flat surface, the measurement model for FLAOA(tiJrward-link AOA) is derived first. Two kinds of position estimation algorithms using FLAOA measurements are proposed; Gauss-Newton method and closed-fonn solution method. With the proposed methods, we can ohtain the attitude of robot as well as its position. Positioning performance of proposed methods is compared by computer simulation. Simulation results show that the closed-form solution method using FLAOA measurements is suitable for indoor robot positioning.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.3
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• pp.99-105
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• 2009

This paper suggests novel signal processing methods for optimal beamforming of smart antenna system in CDMA2000 mobile communication environments. This method utilize characteristics of the reverse pilot channel of CDMA2000 mobile communication systems, and applies them to improve the performance of an adaptive algorithm, which is used to a smart antenna system for beamforming. To perform the best beamforming, it is important to get an exact beamforming algorithm. This paper proposed an algorithm based on Laglange multiplier which has such an adaptive process, and also proposed the method to demodulate the received signal through array antenna using pilot channel in CDMA2000 environment. This paper analysed the enhanced performance of proposed algorithm in various signal environment through signal modeling of physical layer in CDMA2000 reverse link.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1282-1290
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• 1998

In this paper, the physical layer design of IMT-2000 system being developed by SK Telecom is introuduced. The outband signaling scheme and the two-pilot scheme are adopted for multimedia service and inter-cell asynchronous mode respectively. In addition, the synchronous transmission scheme is proposed to reduce the interference in the reverse link. The algorithm and simulation results of 'two-pilot scheme' for inter-cell asynchronous mode and 'reverse synchronous control' for synchronous transmission are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.5
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• pp.1283-1293
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• 1996

This paper descries design concepts, structure and charracteristics of personal communications system based on wideband CDMA under developing for general low-tier mobile telecommunications services as the first step of the next generation mobile telecommunications systems that provide timely exchange of various types of information with anyone, from anywhere, at anytime. Also, wedesign a reverse linktransmitter/receiver structure for personal communications system based on wideband CDMA and validata the performance of the designed structure and establish the each parameter via computer simulation. Simulaation results on the effects of reverse link synchronous transmission and the effects of power control and control and channel coding in pedestrian environment for low-tier services are presented.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1285-1289
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• 2008

Increasing the flood control capacity's link that is enforcing to existing dam by unusual change of weather, While build planing construction by exiting spillway of tunnel type to dam, could know that part bed rock is formed as is different with design. Grasped topography of research area and geology state to definite distribution aspect of different bed rock, Place that achieved Surface geological Survey and correct Survey is difficult in some section enforced Electrical resistivity dipole-dipole investigation. Grasped stratigraphy distribution confirmation and fracture or weathering zone making out siding 2D-Resistivity Electrical resistivity diagram and Reverse analysis diagram, examining closely soil weathered rock rock's distribution state, established stability countermeasure plan

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.804-811
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• 1997

In the CDMA mobile communication system, reverse power control can be used to minimize the interference level for a good quality of the voice channel, and used to maxmize the system capacity. In this paper, we have analyed the environment of the K-parameter and the access procedure for the mobile station, and proposed a new algorithm for the access probe procedure of the station. K-parameter is determined according to the environment of the base station and access probe can adaptively control the power according to the position changes of the mobile station or the rapid and various state changes of the channel. Simulation results in the limited test environment show that it can increase the system capacity and decrease the power comsumption of the mobile station while maintaining the good and stable quality of the voice channel.