• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.3
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• pp.41-49
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• 2011

In this paper, we propose an open protocol to be employed between a smart meter concentrator and a metering data collection server, and also evaluate its performance. Legacy concentrators performs the connection establishment and data gathering operations with DLMS/COSEM protocol standards. However, we note that there are no standardized protocols between the concentrator and the collection server, which inevitably conduces each commercial smart metering system to have its own proprietary protocol. In order to solve this problem, we propose an open protocol - Smart Meter Concentrator Control Protocol(SMCCP) by extending the existing standard protocol(DLMS/COSEM). The SMCCP can provide the proxy mode to enable efficient transmission between the concentrator and the data collection server. It also can support the relay mode to enable a direct communication between the data collection server and each far end smart meter. We also implement an emulator system and a protocol analyzer to provide its operation. In addition, we evaluate the session holding time and the link usage ratio in both relay and proxy modes with OMNET++ simulator.

• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.115-122
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• 2002

This paper presents a new web cluster scheme based on dispatcher which does not depend on operating system for server and can examine server's status interactively. Two principal functions are proposed for new web cluster technique. The one is self-controlled load distribution and the other is transaction fail-safe. Self-controlled load distribution function checks response time and status of servers periodically, then it decides where the traffic goes to guarantee rapid response for every query. Transaction fail-safe function can recover lost queries including broken transaction immediately from server errors. Proposed new web cluster scheme is implemented by C language on Unix operating system and compared with legacy web cluster products. On the comparison with broadcast based web cluster, proposed new web cluster results higher performance as more traffic comes. And on the comparison with a round-robin DNS based web cluster, it results similar performance at the case of traffic processing. But when the situation of one server crashed, proposed web cluster processed traffics more reliably without lost queries. So, new web cluster scheme Proposed on this dissertation can give alternative plan about highly increasing traffics and server load due to heavy traffics to build more reliable and utilized services.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.118-128
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• 2015

Recently BIM technology has been expanded for using in construction project. Due to the high-cost of BIM infrastructure development, lack of regulations, lack of process and so forth, usage of BIM has been delayed than initial expectations. In design phase, especially, collaboration based on BIM system has been a key factor for successful next generation building project. Through the analysis of current research trends about IT technologies, virtualization and BIM service, data exchange such as drawings, 3D model, object data, properties using cloud computing and virtual server system is defined as a most successful solution. The purpose of this study is to enable the cloud computing BIM server to provide several main functions such as editing models, 3D model viewing and checking, mark-up and snapshot in high-performance quality by proper design of VDI system. Concurrent client connection performance is a main technical index of VDI. Through testing of test-bed server client, developed VDI system's multi-connect control is evaluated. Performance-test result of BIM server VDI effect to development direction of cloud computing BIM service for commercialization.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.843-850
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• 2004

As mobile devices prevail, requests for various services using mobile devices have increased. Requests for application services that require large data space such as multimedia, game and database [1] specifically have greatly increased. However, mobile appliances have difficulty in applying various services like a wire environment, because the storage capacity of one is not enough. Therefore, research (5) which provides remote storage service for mobile appliances using iSCSI is being conducted to overcome storage space limitations in mobile appliances. But, when iSCSI is applied to mobile appliances, iSCSI I/O performance drops rapidly if a iSCSI client moves from the server to a far away position. In the case of write operation, $28\%$ reduction of I/O performance occurred when the latency of network is 64ms. This is because the iSCSI has a structural quality that is very .sensitive to delay time. In this paper, we will introduce an intermediate target server and localize iSCSI target to improve the shortcomings of iSCSI performance dropping sharply as latency increases when mobile appliances recede from a storage server.

• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.355-364
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• 2004

These days, various clustering technologies have been adopted to construct web sites. High performance hardware switches have good performance, but have disadvantage of high cost for constructing small and middle-sized web sites. Now a days, many sites have been constructed with the LVS (Linux Virtual Server), which is free of charge and has good performance. Having a centralized load balancing with one front-end, the LVS causes a bottleneck when it receives all at once. In the paper, we suggest a way to remove the LVS bottleneck by providing multiple front-ends. In this architecture, all of cluster nodes act as both a front-end and a back-end. When the load of a node receiving requests is not large enough, the node responds to the client directly. When the load of a node is large enough, the node send the request to a node which is selected by a scheduling algorithm. The scheduling algorithm is discussed to balance loads between servers. While single front-end cluster raises the throughput curvedly, the multiple front-end cluster raises the throughput linearly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.327-333
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• 2013

In this paper, we propose a QoS information collection method at the information server in maritime networks with multi-network interfaces, and a route selection scheme based of the measured predictive QoS information comparing with parameters requested from a mobile node in a ship entering into a harbor from near-shore area. By changing network conditions and applying various application bandwidths, we check the operation of our proposed scheme and measure its performance of the original and proposed schemes in the viewpoints of the received packet traffic and end-to-end delays.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.429-432
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• 2002

The existing recovery technique using the logging technique in the client/sewer database system only administers the log as a whole in a server. This contains the logging record transmission cost on the transaction that is executed in each client potentially and increases network traffic. In this paper, the logging technique for redo-only log is suggested, which removes the redundant before-image and supports the client-based logging to eliminate the transmission cost of the logging record. Also, in case of a client crash, redo recovery through a backward client analysis log is performed in a self-recovering way. In case of a server crash, the after-image of the pages which needs recovery through simultaneous backward analysis log is only transmitted and redo recovery is done through the received after-image and backward analysis log. Also, we select the comparing model to estimate the performance about the proposed recovery technique. And we analyzed the redo and recovery time about the change of the number of client and the rate of updating operation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.921-940
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• 2015

In this paper, we investigate the multi-resource allocation problem, a unique feature of which is that the multiple resources can compensate each other while achieving the desired system performance. In particular, power and time allocations are jointly optimized with the target of energy efficiency under the resource-limited constraints. Different from previous studies on the power-time tradeoff, we consider a multi-server case where the concurrent serving users are quantitatively restricted. Therefore user selection is investigated accompanying the resource allocation, making the power-time tradeoff occur not only between the users in the same server but also in different servers. The complex multivariate optimization problem can be modeled as a variant of 2-Dimension Bin Packing Problem (V2D-BPP), which is a joint non-linear and integer programming problem. Though we use state decomposition model to transform it into a convex optimization problem, the variables are still coupled. Therefore, we propose an Iterative Dual Optimization (IDO) algorithm to obtain its optimal solution. Simulations show that the joint multi-resource allocation algorithm outperforms two existing non-joint algorithms from the perspective of energy efficiency.

• The KIPS Transactions:PartA
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• v.11A no.3
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• pp.129-138
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• 2004

Even though the Internet applications such as e-mail and FTP are widely used, fax is still an important media for data communications till today. Many researches on security over the Internet data communication have been done over the years, on the other hand not many researches have been dedicated to the fax security issue which is as important as the Internet. In this paper, we describe the development of hardware and software of the embedded security fax server which increases the security in supporting existing fax. The developed system is designed and implemented to maintain security while minimizing the delay due to encryptionㆍdecryption. Since there's international or domestic tryptographic standard and each nation have their policy to restrict the use of cryptographic system, we adopt domestic standard cryptographic protocol admitted in Korea. And the system supports two modes： Security mode and Non-Security mode that user can choose from. The system can be applied directly which is the requirements of users at company ,End the government. We verify the performance and functioning of the system in various real environment.

• IE interfaces
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• v.16 no.4
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• pp.421-431
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• 2003

Due to the increasing complexity of the information systems environment, modern information systems are facing more difficult and various security risks than ever, there by calling for a higher level of security safeguard. In this paper, an information technology security risk management model, which modified by adopting the concept of business processes, is applied to client/server distributed systems. The results demonstrate a high level of risk-detecting performance of the model, by detecting various kinds of security risks. In addition, a practical and efficient security control safeguard to cope with the identified security risks are suggested. Namely, using the proposed model, the risks on the assets in both of the I/O stage(on client side) and the request/processing stage(on server side), which can cause serious problems on business processes, are identified and the levels of the risks are analyzed. The analysis results show that maintenance of management and access control to application systems are critical in the I/O stage, while managerial security activities including training are critical in the request/processing stage.