• Journal of KIISE:Computing Practices and Letters
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• v.7 no.2
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• pp.183-192
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• 2001

In a development environment for embedded system with a connection between host and target system, the linker of host system links the cross-compiled object file and modules of target system and downloads the linked object file to the target system. In this research, we separate this linker into the module dependent on object file format and the module independent on object file format. The dependent module gets the linking information independent on file format from the object file, and the independent module actually does the linking process with this linking information_ This separation can improve the portability of development environment for a target system_ Also, our linker does the incremental remote linking that applies relocation not only to the obj ect file to be loaded but also to target's modules to have been loaded_ This incremental remote linking can reduce a linking time than linking by the united modules because of linking by module. The result of measuring linking time for SPEC95 integer benchmarks shows an average of reduction rates of 64.90%. Also, incremental remote linking can improve the comfortability of users who develop programs because users do not consider a downloading order of linking object files. Currently, we developed this linker in the embedded application development environment ESTO [1] to be prepared for a commercial product.

• The Transactions of the Korea Information Processing Society
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• v.6 no.10
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• pp.2587-2596
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• 1999

Recently, by the extension of skills like LAN, the wireless telecommunication network and the satelite services make it possible for the mobile computer users to access a database. A method to use the replicated database on a server to get new data without missing any information has been being studied. So far we have used the Static Replica Allocation(SRA) for the replication which is the method of the replication on the server. This method is to replicate the data on the replica server after a moving host is transferred to a cell. Since the network of the SRA is very good, and if there are few moving users, no trouble will happen. But if there is no moving users in a cell, the data will not be shared. Therefore, this paper is about the study of the method of relocation after replicating the data to the cells for the users(User Select Replica Allocation : USRA). We also analyze the access rate and the possibility which are closely related to the moving frequency of the mobile hosts and the numbers of the cells. As a result, We show that the 120% lower access cost and the 40%∼50% gains are achieved from the low mobility

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.243-250
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• 2010

Vehicular communication networking is one of the most important building blocks of Intelligent Transportation System (ITS). The vehicular communication network is a wireless communication system enabling vehicles to communicate with each other as well as with roadside base stations. Mobility management of vehicles which move at high speeds and occasionally make a long journey is an interesting research area of vehicular communication networks. Recently, The Proxy Mobile IPv6 (PMIPv6) protocol is proposed for network-based mobility management to reduce the overhead of mobile nodes. PMIPv6 shifts the burden of the mobility management from mobile nodes to network agents to decrease the overhead and latency for the mobility management. In this paper, we derive the scenario of deploying PMIPv6 in vehicular communication networks and propose a new LMA handover mechanism for realizing the scenario. By carrying out the ns-2 based simulations, we verify the operability of the proposed mechanism.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.149-159
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• 2000

In mobile computing environments, invalidation and propagation method based on broadcasting is used to transmit the information for cache maintenance of mobile hosts. Previous researches generally adopted invalidation method that easily adapts to the limited network bandwidth and the frequent disconnection. But the invalidation of frequently accessed data causes the contention on the wireless network with the increasing cache requests. Although the propagation method can reduce the cache requests, the high probability of broken message or loss of message is the main factor that degrades the system performance. To resolve these problems, we propose adaptive cache maintenance scheme that dynamically adjusts the broadcasting ratio of invalidation and propagation, according to the wireless network connection states. The proposed scheme broadcasts the propagation message in stable connection state, so it can reduce the cache requests and server response time. With the decreasing available network bandwidth by the frequent partial disconnection and disconnection, the proposed scheme dynamically increases the broadcasting ratio of the invalidation messages to minimize the broken message or the loss of message probability. Consequently, the proposed scheme resolves the problems which arise in the invalidation or propagation method in mobile computing environments.

• Journal of KIISE:Databases
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• v.30 no.3
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• pp.310-319
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• 2003

Workflow is defined as the automation of a business process, and consists of interrelated workflow tasks. Because many modem business processes nay involve activities that are geographically distributed between different departments or organizations, workflow inherently has the characteristics of distribution. In distributed workflow systems, each workflow task performs its assigned role by utilizing information resources placed at some hosts, and then transmits workflow execution control to the next tasks in a workflow definition. Hence, it is very important to appropriately allocate workflow tasks to hosts for high performance workflow processing. In this paper, we propose a multilevel workflow graph partitioning scheme for efficient placement of workflow tasks. This method can improve the performance of workflow processing by minimizing the remote communication costs occurred during workflow execution.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.8
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• pp.930-938
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• 1999

미래의 통합 이동 통신망은 멀티미디어 데이터 서비스를 하기 위해 작은 셀로 망이 구성될 것이다. 셀이 작은 경우, 이동 호스트의 셀간 이동이 상대적으로 증가해서 잦은 핸드오프 처리로 서비스 중단이 빈번히 발생할 수 있을 뿐만 아니라 자원의 낭비도 많아지게 된다. 따라서 이런 문제를 해결하기 위해 이동 호스트의 이동성을 예측해서 멀티캐스트 연결을 구성해서 사전 핸드오프 처리를 하는 SGMH방법을 제안한다. SGMH방법의 성능 평가를 위해 핸드오프 처리과정의 데이터 및 제어 정보의 흐름을 분석하고, 망 종속 인자들을 도입해서 버퍼 오버헤드와 서비스 중단 시간 면에서 기존 핸드오프 방법들과 비교했다. 비교 분석한 결과는 제안한 방법이 기존의 방법보다 기지국에서의 버퍼 오버헤드뿐만 아니라 서비스 중단 시간을 줄일 수 있음을 보였다.Abstract For mobile multimedia data services, future mobile communication networks will consist of small cells. In case of smaller cell size, the number of user movements between cells will increase and more network resources will be consumed for processing frequent handoffs. This processing delay will cause frequent connection service disruptions. To solve these problems, a multicast-based handoff method ,called SGMH(Sub-Group Multicast-based Handoff), is suggested. SGMH method estimates future movements of mobile hosts and setups a dynamic multicast connection tree for procesing handoffs. For performance evaluation, we represent flows of data and control messages as timing diagrams and introduce several network related factors. In terms of buffer overhead and service disruption time we compared the SGMH method to other methods. The results show that SGMH method has better performance in that it can reduce consumption of network resources and minimize service disruption time.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.259-260
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• 2019

Through Korean Smart-Navigation Project we are tasking with a VDES test network construction and service solution development. In this task, we design a structure that interoperates the VDES network with the service host/client simulator which is communication framework for efficient and reliable and seamless service. The proposed structure includes interface design between VDES test equipments which is VDES shore station, mobile station, gate way, service host and client. And detailed design includes message definition, interface design, operation scenario, equipment design and implementation for VDES test network. After implementing these test equipments with proposed design, we will firstly proceed the test equipment integration and interface test indoors for VDES test network. After fully verifing the VDES test network through indoor tests, we will construct the VDES shore station and mobile station and conduct the sea area tests by 2020.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.5
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• pp.369-378
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• 2003

This paper presents design and VLSI implementations of a reassembly processor for ATM/AAL. The assembly processor is responsible for processing ATM cells from the receive physical interface. It controls the transfer of the AAL payload to host memory and performs all necessary SAR and CPCS checks. We propose the improved structure of cell identification algorithm and smart scatter method for host memory management. The proposed cell identification algorithm quickly locates the appropriate reassembly VC table based on the received VPI./VCI channel value in the ATM header. The cell identification algorithm also allow complete freedom in assignment of VCI/VPI values. The reassembly processor uses a smart scatter method to write cell payload data to host memory. It maintains the scatter operation and controls the incoming DMA block during scatter DMA to host memory. The proposed reassembly processor can perform reassembly checks on AAL. OAM cell. For an AAL5 connection, only CPCS checks, including the CRC32, are performed. In this paper, we proposed a practical reassembly architecture. The design of reassembly processor has become feasible using 0.6${\mu}{\textrm}{m}$ CMOS gate array technology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.2911-2918
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• 2014

Nowadays, most Internet servers run on virtual a network which connects each virtual machine, to process large amounts of data on single physical computer. The virtual machines for their own purposes are interconnected to other virtual server systems with various types of operating systems. Each virtual server may share one physical computer resources and operates at a service seamlessly to each other. Sometimes even the virtual machines are implemented using a method that lease the physical IT resources without purchasing physical server. Therefore, a virtual switch is needed to improve the performance when a large number of virtual machines operate on physical server. In this study, the implementation and investigation was performed for the virtual switches, OpenvSwitch and DPDKvSwitch, in order to provide the necessary high-performance cloud services to creative business.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10A
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• pp.736-745
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• 2009

The growth of mobile devices and the increase of using them have required the support of realtime multimedia application in wireless environments. Especially, wireless ad-hoc networks without central management system and with dynamically changing network topology need much researches of QoS routing for multimedia applications. However it is impossible to support the hard realtime QoS for these dynamic networks. In this paper, we propose a QoS routing scheme by using QoS DAG that is maintained by each mobile node and contains the QoS information for neighbor nodes. In order to maintain the QoS DAG, each node transmits its QoS information to neighbor nodes by local broadcasting, and the neighbor nodes update their QoS DAGs by the received message. In our proposed scheme, it is possible to search the QoS path efficiently by the QoS DAG without searching it in the whole network.