• Journal of Advanced Navigation Technology
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• v.21 no.6
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• pp.585-592
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• 2017

Recently, as the air traffic volume has been explosively increased, various studies are being conducted to increase the air passenger capacity. In order to compensate the limitation of the separation distance on the aerodrome established on the basis of existing VOR / DME equipment, GNSS utilizing satellite is considered. In addition, we are trying to obtain more precise location information by using SBAS, a system that can correct GNSS error. ICAO recommends introducing SBAS until 2025, and Korea has also started to develop KASS, a Korean SBAS since 2014. Therefore, in this paper, we analyze the interference threshold for the measurement items and the receiving antenna gain according to the elevation angle of the satellite receiving antenna.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.517-526
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• 2006

In order to achieve high capacity and reliable link quality in wireless communication, the significant efforts should be concentrated on mitigating interference between cells. To solve the interference problem, the newly introduced concept of a Distributed Wireless Communication System (DWCS) can provide the capability of joint control of the signals at multiple cells. This paper proposes a new concept of virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. The proposed system manages two kinds of virtual cell. One is the Active Virtual Cell which exists for user's actual data traffic and the other is the Candidate Virtual Cell which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. The proposed system constructs DVC by using antenna selection method. Also, for multi-user high-rate data transmission, the proposed system introduces multiple antenna technology to get a spatial and temporal diversity gam and exploits space-Time Trellis Codes known as STTC to increase a spectral efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.33-42
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• 2001

We consider a model describing large scale performance of multiservice networks supporting both constant- and adaptive-rate services. As the number of constant-rate connection changes over time in multiservice networks, the available bandwidth for adaptive-rate connections changes as well. We estimate the available bandwidth for adaptive-rate service in a dynamically changing traffic environment based on Erlang fixed point equation and Little\`s law. The bandwidth allocation for adaptive-rate service is determined by the max-min fairness criterion. We find an upper bound on the average minimum throughput for adaptive-rate service, and 7how that the bound is achieved in large-capacity networks. This is verified using network examples. Since max-min fair allocation may not maximize the total throughput or revenue in a network, we consider adjustments via network level priority schemes to increase efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1276-1285
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• 2007

Since the TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) system is based on TDD (Time Division Duplexing), the uplink and downlink can be allocated asymmetrically according to the traffic e.g. Web browsing. Although this asymmetric allocation can increase the frequency utilization, it may cause time slot opposing, which implies the time slot is assigned in opposing direction between cells. The time slot opposing can generate significant interference between cells, which results in severe performance degradation. In the paper, a novel dynamic channel allocation (DCA) is proposed in the TD-SCDMA system, to mitigate the impact of time slot opposing considering smart antenna. When the smart antenna is applied in the system, the inter-cell interference is largely affected by beam pattern and beam direction between neighboring cells. Therefore, the time slot opposing and smart antenna should be considered together in the DCA. The intensive simulations show that the proposed scheme can improve the system capacity compared to the conventional DCA schemes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.6 s.360
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• pp.31-39
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• 2007

In this paper, a system for real-time or periodic measurement and analysis of RF parameters such as forward transmit power and pilot power in CDMA base station systems is proposed. Such RF characteristic parameter measurement can be prevented from system fault and used to achieve optimal service quality and maximum investment return through cell coverage expansion, subscriber capacity increase and so on. For forward power measurement, the local oscillator frequency for the detector is varied so that the transmit power for all channels can be measured. The channel power measurement can be used to analyze the variation in transmit power for changes in voice traffic. By comparing to forward $E_c/I_o$, the pilot channel power can be deducted, which can be used to determine uy degradation in transmit section modules such as the high dover amplifier. Since an accurate analysis of carefully measured data using the CDMA level detector must be made, the system is designed so that measurement errors due to changes in crest factor with modulation method can be overcome.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6385-6390
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• 2015

With bending moment, torsional moment due to geometric properties as "Initial curvature" acts in horizontally curved I-girder. These behavior causes the secondary effect of bending in minor-axis because of interaction between bending and torsion. The bending and torsion interaction cause a loss of load bearing capacity by induced the early inelastic or plasticity condition in curved girder. Also eccentric load by movements of traffic can increase torsion. However, Equation of interaction between bending and torsion for straight girder, not deal with characteristics of curved girder behavior in previous studies, can be overestimated for ultimate strength in horizontally curved I-girder acting vertical force. Therefore, using more rational, obvious suggestion is required when design curved girder. In this study, we identified the bending-torsional moment interaction for the horizontally curved I-girder of the eccentric load acting by FEM analysis.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.105-116
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• 2007

A ROUNDABOUT is more effective way to improve safety and prevent delays than signal intersection. ROUNDABOUT has been known highly safe treatment that could be used as a method to reduce conflicts between vehicles, to reduce travel speed in inner or approach of intersection, and to have no speed difference between drivers than intersection. In this study, the effective analysis on the installation of ROUNDABOUT was carried out using computer-based simulation tool VISSIM, in order to evaluate performance and safety of ROUNDABOUT and develope a warrant. In conclusion, the results indicated that there was remarkable increase of Y-intersection capacity and decrese of delay, and improvement of traffic safety. Finally, A nice feature of this study is to firstly attempt to use microscopic simulator to evaluate the effectiveness of ROUNDABOUT and suggest a passible operation boundary.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.468-471
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• 2010

MOST150, which has a higher bandwidth than of MOST25, appears to satisfy the demand for the automotive infotainment system and to increase the multimedia processing capacity, and the various technology applications are required for the accomplishment of MOST150 development. The MOST25 network technology is being restrictively equipped with some of the car models but the problems with bandwidth and compatibility has arisen. In order to solve this, the MOST150 technology has been developed and further research is being carried out to apply the technology to the automobile industry. Thus, for the effective process of the Ethernet traffic in the realization of MOST150/Ethernet Gateway for automobile, we, in the research, shall analyse the Management Mapping method, including the MOST150's Isochronous channel, the MOST Ethernet Packet channel, and etc. and study the efficient algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.780-783
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• 2009

The application of MOST150 technology has been required to satisfy the demand for the automotive infotainment system and the higher bandwidth requirements caused by the increase of the multimedia processing capacity. The Ethernet technology applied gateway was implemented for an efficient transmission of multimedia, a vehicle diagnosis, an external communication, a data processing between the MOST150 and the CAN communication method applied to many existing vehicles. The new algorithm and application were suggested in order to efficiently perform the data processing between other types of communication systems. The existing MOST150 frame is mainly composed of the Control Channel, the Legacy Packet Channel(async) and the Synchronous /Isochronous Channels and performs the data processing through these sequential channels. With the sense of this process, this study suggested the new algorithm that the Mapping method of the IETF's QoS Management was applied to the MOST150 technology for the efficient QoS.

• Journal of Advanced Navigation Technology
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• v.25 no.1
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• pp.78-83
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• 2021

Due to rapidly increasing air traffic congestion and airspace restrictions, the International Civil Aviation Organization (ICAO) is urging all aircraft to use SBAS by 2025, in order to implement Performance-based navigation to increase airspace capacity. In line with this, research and development of Korean-style SBAS, which reflects the characteristics of Korea's airspace environment, continues in Korea. Since there is no flight inspection procedure for performance testing and verification of SBAS in Korea yet, this paper analyzes FAA, ICAO Regulations, and laws enacted by the Ministry of Land, Infrastructure and Transport to derive essential evaluations and parameters of Korean SBAS, and presents the optimal design using RTK-DGPS as a position fixing system.