• Journal of Korea Society of Industrial Information Systems
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• v.9 no.3
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• pp.1-10
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• 2004

Video-On-Demand servers use compression techniques to reduce the storage and bandwidth requirements. The compression techniques make the bit rates of compressed video data significantly variable from frame to frame. Consequently, Video-On-Demand servers with a constant bit rate retrieval can not maximize the utilization of resources. It is possible that when variable bit rate video data is stored, accurate description of the bit rate changes could be computed a priori. In this paper, I propose a buffer management scheme called MAX for Video-On-Demand server using variable bit rate continuous media. By caching and prefetching the data, MAX buffer management scheme reduces the variation of the compressed data and increases the number of clients simultaneously served and maximizes the utilization of system resources. Results of trace-driven simulations show the effectiveness of the scheme.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.184-186
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• 2007

IHO S-57 is the standard intended to be used for the exchange of digital hydrographic data between hydrographic offices, and for the distribution of hydrographic data to manufacturers. mariners and other data users. But it was primarily developed to meet the ENC requirement called for in an IMG-compliant ECDIS. As presently structured, it cannot support .future requirements such as gridded bathymetry or time-varying information. To improve this limitations, IHO is developing new digital hydrographic standard, S-100. In this paper, we analyze the S-100 standards and propose the method for development of digital hydrographic data according to S-100.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.6
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• pp.318-330
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• 2002

This paper discusses the design and implementation of a video server which uses tertiary device, such as magneto-optical jukebox or tape library, as a source of media archiving. In order to handle the tertiary device in the framework of disk-based stream service model, a sophisticated streaming model is required for server and it should consider the device-specific performance characteristics of tertiary storage. We have carefully designed the streaming mechanism for server whose key functionalities include stream scheduling, disk caching and admission control. The proposed system has been implemented on Windows 2000 platform which is equipped with a magneto-optical jukebox. The design principles of the server are validated with the experiments and the performance characteristics is analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.385-392
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• 2006

It is widely accepted that high user densities in mobile multimedia environments can only be achieved with micro- and pico-cell. The smaller cell size causes frequent handovers between cells, and decreases permissible handover processing delay. This may result in the handover failure, in addition to the loss of some packets during the handover. In these cases, re-transmission is needed in order to compensate errors, which in turn triggers a rapid degradation of throughput. In this paper, we propose a new handover scheme for the next generation mobile communication systems, in which the handover setup process is done in advance before a handover request by predicting the handover cell based on mobile terminal's current position and moving direction. Simulation is performed in order to analyze the handover failure rate and packet loss rate. Simulation results show that our proposed method provides a better performance than the conventional method.

• Information Systems Review
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• v.6 no.2
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• pp.209-225
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• 2004

This study shows the field of construction which was less developed in the aspect of information system in comparison to other areas needs to introduce construction information system and suggests it can make more value linked with company performance through the system. For the first step, it emphasizes the integrated enterprise approach not optimization of each sector in a company. This paper extracts the current issues of construction information from the core process of construction area and implies a driving plan and the future development plan for construction information. Antecedent studies for this drew the information structure model and the construction information-driving model of a construction company. Hence, case studies with management companies that implemented the construction information system successfully tested validity. This research brings the cases of PMS, the integrated finance system, and CRM system as successful ones.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1006-1009
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• 2015

Power-line communication technology is proposed to identify power transformers to serve customers in 3 phase -4 wires power distribution systems. Mathematical models for 3-phase power transformers, 3-phase wire lines, and customer loads are described to investigate the transmission characteristics of high frequency power line carrier. From the analysis, distribution line cable circuits have only a limited ability to carry higher frequencies. Typically power transformers in the distribution system prevent propagating the higher frequency carrier signal. The proposed method uses the limited propagation ability to identify the power transformer to serve customers. A novel power transformer identification system is designed and implemented. The system consists of a transmitter and a receiver with power-line communication module. Some experiments are conducted to verify the theoretical concepts in a big commercial building. Also some simulations are done to help and understand the concepts by using MATLAB Simulink simulator.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.3
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• pp.459-466
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• 2017

One of the most widely-used open source project; OpenSSL is a cryptography library that is used to secure most web sites, servers and clients. One can secure the communication with the Secure Socket Layer (SSL) or its successor, Transport Layer Security (TLS) protocols by using the OpenSSL library. Since cryptography protocols will be updated and enhanced in order to keep the system protected, the library was written in such a way that simplifies the integration of new cryptographic methods, especially for the symmetric cryptography protocols. However, it gets a lot more complicated in adding an asymmetric cryptography protocol and no guide can be found for the integration of the asymmetric cryptography protocol. In this paper, we explained the architecture of the OpenSSL library and provide a simple tutorial to modify the OpenSSL library in order to accommodate custom protocols of both symmetric and asymmetric cryptography.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11S
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• pp.3684-3693
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• 2000

In this paper, performance of a nonblocking high speed packet switch with switching capacity m which adopts a dynamic priority control function (DPCF) of a threshold- based Bernoulli priority jump (TBPJ) scheme is considered. Each input queue has two separate buffers with different sizes for two classes of traffics, delay-sensitive and loss-sensitive traffics, and adopts a TBPJ scheme that is a general state-dependent Bernoulli scheduling scheme. Under the TBP] scheme, a head packet of the delay-sensitive traffic buffer goes into the loss -sensitive traffic buffer with Hernoulli probability p according to systems states that represent the buffer thresholds and the number of packets waiting for scheduling. Performance analysis shows that TBPJ scheme obtains large performance build-up for the delay-sensitive traffic without performance degradation for the loss-sensitive traffic. In addition to, TBP] scheme shows better performance than that of HOL scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.509-516
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• 2008

Recently, the operator modules to control external devices are concerned about automatic management system to process continuously changed signals. These signals are the stream data of which characteristics are several numbers. a short report interval and asynchronous report time. It is necessary that the system brings about high accuracy and real time process for stream data. The typical queries of these systems consist of the current query to search the latest signal value, the snapshot query at a past time, the sliding window query from a past time to current. In this paper, we propose the efficient method to manage the above signals by using a file structured database in small-size operating systems. We also propose a query model to accommodate various queries including the sliding window query. The file database in the QNX adopts a delta version and a shared memory buffering method for the resource limit of a small storage and a low computing power.

• Journal of the Korea Society of Computer and Information
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• v.29 no.6
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• pp.131-141
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• 2024

The aging population and worsening lifestyle habits have increased the risk of chronic diseases. This has heightened the importance of preventive healthcare, particularly through personalized health management services based on individual health data. Despite this, the domestic digital healthcare industry remains underdeveloped. Given the need for acceptance from both consumers and providers, this study uses the Analytic Hierarchy Process (AHP) to identify success factors for health management service platforms. AHP evaluates the relative importance of various factors to aid decision-making. Results show that providers prioritize data analysis and platform design, laws and regulations, and data standardization, while consumers prioritize system stability, laws and regulations, and system security. These findings highlight the need for strategies to bridge the expectation gap to effectively promote health management service platforms.