• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.3-9
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• 2005

무선통신 기술과 정보 기술을 이용해서 사용자 무선 단말에 다양한 정보를 제공하는 텔레매틱스 서비스는 차량 운전자, 탑승자 및 보행자 등 사용자에 따라 다양한 형태의 서비스로 진화하고 있다. 또한 무선통신망의 발전으로 인해 광대역 통신의 대용량 텔레매틱스 서비스로의 발전이 기대되고 있다. 본 논문에서는 텔레매틱스 서비스 중에서 대중교통의 편리한 사용을 위한 보행자 위주의 길안내 서비스에 대해 논한다. 보행자 대중교통 안내 서비스를 위한 요구 사항을 기반으로 서비스 기능을 정의하고 서비스를 분류함으로써 보행자의 도보 및 대중교통 안내 서비스를 제안한다. 보행자 대중교통 안내 서비스는 보행자 도보 길안내 기능, 출발지와 목적지 기반의 One-Stop 대중교통 안내 기능, 대중교통 정보 제공 기능, 경로 예약 기능, 개인화 기능으로 분류할 수 있으며 각 기능의 정의 및 구성 요건들을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6B
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• pp.563-572
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• 2003

When the Mobile IP is applied for mobility management protocol in the next-generation mobile communication networks, it can cause a serious performance degradation called micro-mobility problem. In this paper, we propose ANMM(Access Network Mobility Management) to efficiently support micro-mobility in the IP-based wireless access network. The ANMM scheme can reduce the handoff latency and signaling overhead resulting in performance enhancement by managing the mobility of mobile nodes within access network.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.325-326
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• 2011

전력선 통신기반 기술이 발전됨에 따라 원격검침시스템의 설치 및 유지관리에 필요한 망관리시스템기술도 함께 개발되어 운영되고 있으나 통합검침서비스를 제공하기 위해서 추가되는 무선통신노드의 관리에 대해서는 아직 적용된 바가 없다. 국내 구축된 전력선통신망의 셀 중심에는 칩 셋 벤더가 제공하는 망 관리유닛으로 망관리 정보를 모으고 SNMP기반으로 서버로 전송하는 Proxy agent 망관리구조를 가진다. 본 논문에서는 통합검침을 위한 주요 무선통신 노드인 댁내집속장치와 무선계량미터기관리를 위한 방안을 제시하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.26-33
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• 2003

The SSB(Single Side Band) communication in the 27MHz band has mainly been using between fishiery station and small fishing ship less than 101ons, but the most of small fishing ship are depend on cellular system. When accident for small ship at sea happens, It's very important to communicate continuously for preventing the collision and taking action. At present it is hard to control small fishing ship and provide information properly by using 27MHz SSB channel. Therefore in this paper We present TRS communication system applied for small fishing ship to protect the safety and life at sea and to prepare for emmergency, and also validate it's application.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.965-973
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• 2007

We analyzed that the loss of data in TCP protocol based wireless networks caused by overlapped responses in bi-directional nodes that were resulted in out of the data sequence. This loss can be prevented by using revised TCP rate control algorithm and the performance of throughput can also be improved. The rate control algorithm is applied when the congestion happens between nodes while traffic packets are retransmitting in TCP bandwidth. In addition to applying the rate control algorithm, we determine the number of system clients in bandwidth and the average of pausing time between transmitting serial files to produce a competitive level so that an efficient performance of rapid retransmitting for the loss of multi-packets. This paper discusses the improvement of congestion control in that the decrease of the loss, firstly, as ensuring an efficient connection rate and, secondly, as using sliding window flow control.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.196-201
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• 2002

The SSB(Single Side Band) communication in the 27MHz band has mainly been using between fishiery station and small fishing ship less than 10tons, but the most of small fishing ship are depend on cellular system. When accident for small ship at sea happens, It's very important to communicate continuously for preventing the collision and taking action. At present it is hard to control small fishing ship and provide information properly by using 27MHz SSB channel. Therefore in this paper We present TRS communication system applied for small fishing ship to protect the safy and life at sea and to prepare for emmergency, and also validate it's application.

• Journal of Korea Multimedia Society
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• v.10 no.9
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• pp.1153-1164
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• 2007

One of the most challenging technical issues in mobile communication for multimedia is Quality of Service (QoS) management of handover calls. This paper proposes a 2-level handover control system to copy with this problem. A 2-level handover control system consists of resource reservation and call admission control modules. The resource reservation module divides the network resource into Hard and Soft reserved resource. The Hard reserved resource is only for the handover calls while the Soft reserved resource is for both the handovers and the new calls. And also, the resource reservation module classifies handovers into primary and secondary handovers based on often they occur. The call admission control module deals with the primary and secondary handover calls in different ways. The new calls can use Soft reserved resource only if there is sufficient amount available in the Hard reserved resource. Proposed system is evaluated using an M/M/c/c queueing model. It is shown that proposed system allows more efficient utilization of network resource without degrading QoS comparing with the legacy handover control systems.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.19-27
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• 2010

In this paper, we propose a scheme for real-time data retransmission in LR-WPAN to support the required QoS even in the severe channel error environments. In IEEE 802.15.4a, as the user data rate is supported up to 850Kbps, the real-time streaming data can be transferred more easily. In this research, we study the beacon-enabled mode in IEEE 802.15.4 LR-WPAN standard. In the proposed scheme, special slots are dynamical1y assigned for retransmission of the packet that fails during a real-time data service, and in the severe channel error environments a time diversity is acquired. Analytical results show that the proposed scheme is more robust and achieves a much higher throughput than the previous protocol in LR-WPAN.

• The KIPS Transactions:PartC
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• v.19C no.3
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• pp.209-214
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• 2012

Time synchronization is important role in a network, especially in Wireless Sensor Network (WSN) which is required for time-critical applications such as surveillance, tracking, data fusion and scheduling. Time synchronization in WSN should meet the other different requirements than the one in other networks because WSN has critical resource constraints, especially power consumption. This paper presents a new time synchronization scheme for WSN, which is energy efficient by reducing communication overhead. Simulation test shows this new scheme has better energy efficiency and performance of accuracy than existing schemes proposed previously.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.4
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• pp.555-560
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• 2017

Currently, railway wireless communication systems adopt several communication schemes depending on the specific region. To increase data rate and achieve high fidelity in railway wireless communication systems, LTE-R scheme has been developed. In this paper, We introduce interoperability technology which converges several railway communication systems including LTE-R. First, we consider two interoperability methods and their standardization. Some empirical test results of interoperability technology are also introduced. It is expected to provide seamless and statable railway communication environments by applying interoperability technologies to railway wireless communication systems.