• 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.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.12
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• pp.497-504
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• 2018

This paper studies about the Oriental Medical Expert System, based on Open Source Drools for rule engine processing, which contains scalability, availability, and modifiability. The system is developed with the Spring MVC framework and Ajax for stable services of the Web-based Medical Expert System. The diagnosis and treatment process of this Medical Expert system provides a service that provides the general users to accesses the web with a series of questionnaires. In order to compensate for the asynchronous communication between clients and services, and also for the complicated JDBC weaknesses, we applied the data handling in JSON to reduce the servers' loads, and also the Mybatis framework to improve the performance of the RDBMS, respectively. In addition, as the number of users increases to cope with the maximum available services of the web-based system, the load balancing structure using Nginx has been developed to solve the server traffic problems and the service availability has been increased. The experimental results show the stable services by approving the scalability test.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.67-75
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• 2003

The development of mobile phone is growing fast in the all over the world. Besides the basic voice communication, many multimedia services and global roaming service are capable in the 3rd generation mobile telecommunication. Because mobile phone has been the essential tool to communicate, the protection of privacy and the safe transmission are critical ones. In synchronous, asynchronous mode IMT2000 service, the mechanism of mutual authentication and generation of cipher key and integrity key are implemented in smart card chip called UIM, USIM. In this paper, we describe the authentication mechanism of 3GPP and 3CPP2 and its implementation results. Then, we specify a few problems which are not defined in standard.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2852-2858
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• 2022

A proton therapy facility is under development at Huazhong University of Science and Technology (HUST). To meet the need for fast energy changes during treatments, a beamline control system (BCS) has been designed and implemented. The BCS coordinates and controls various beamline devices by adopting a distributed architecture divided into three layers: the client, server, and device layers. Among these, the design of the server layer is the key to realize fast energy changes. The server layer adopts the submodule programming paradigm and optimizes the data interface among modules, allowing the main workflow to be separated from the device workflow and data. Furthermore, this layer uses asynchronous, multithreaded, and thread-locking methods to improve the system's ability to operation efficiently and securely. Notably, to evaluate the changing energy status over time, a dynamic node update method is adopted, which can dynamically adjust the update frequency of variable nodes. This method not only meets the demand for fast updates on energy changes but also reduces the server's communication load in the steady state. This method is tested on a virtual platform, and the results are as expected.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.4
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• pp.421-429
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• 2000

In present, ATM integrated switching system has been developed to a mixed modules that complexed switching system including maintenance, operation based on B-ISDN/LAN service and plug-in module, , which runs on workstation computer system. Meanwhile, workstation has HMI operation system feature including file system management, time management, graphic processing, TMN agent function. The workstation has communicated with between ATM switching module and clients. This computer system architecture has much burden messages communication among processes or processor. These messages communication consume system resources which are socket, message queue, IO device files, regular files, and so on. Therefore, in this paper we proposed new performance modeling with this system architecture. We will analyze the system bottleneck and improve system performance. In addition, in the future, the system has many additional features should be migrated to workstation system, we need previously to evaluate system bottleneck and redesign it. In performance model, we use queueing network model and the simulation package is used PDQ and C-program.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.54-67
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• 2000

It is known that the performance of a DS-CDMA system mainly depends on Multiple Access Interference(MAI). The effect of MAI in a reverse link is larger than that of a forward link because of the absence of orthogonality among mobile stations. In this paper we investigate the effect of synchronous transmission in the reverse link, which is compared to the performance of asynchronous transmission in the reverse link. In addition, we consider the effect of interference from Mobile Stations(MSs) in a hand-over region. That is, if we assume that a MS is moving from a serving base station(sowing BS) to a target base station(target BS), the signal of the MS is not orthogonal with the signals of all other MSs within the target BS because the MS is only synchronized with the serving BS. Finally we suggest an interference cancellation scheme to reduce the interference from MSs in the region of hand-over, which can be one of solutions for the capacity degradation due to interference from the MSs in the hand-over region in reverse link synchronous transmission.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1107-1114
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• 2004

System Packet Interface Level 4 Phase 2(SPI-4.2) is an interface for packet and cell transfer between a physical layer(PHY) device and a link layer device, for aggregate bandwidths of OC-192 ATM and Packet Over Sonet/SDH(POS), as well as 10Gbps Ethernet applications. SPI-4.2 core consists of Tx and Rx modules and supports full duplex communication. Tx module of SPI-4.2 core writes 64-bit data word and 14-bit header information from the user interface into asynchronous FIFO and transmits DDR(Double Data Rate) data over PL4 interface. Rx module of SPI-4.2 core operates in vice versa. Tx and Rx modules of SPI-4.2 core are designed to support maximum 256-channel and control the bandwidth allocation by configuring the calendar memory. Automatic DIP4 and DIP-2 parity generation and checking are implemented within the designed core. The designed core uses Xilinx ISE 5.li tool and is described in VHDL Language and is simulated by Model_SIM 5.6a. The designed core operates at 720Mbps data rate per line, which provides an aggregate bandwidth of 11.52Gbps. SPI-4.2 interface core is suited for line cards in gigabit/terabit routers, and optical cross-connect switches, and SONET/SDH-based transmission systems.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.9
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• pp.293-300
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• 2014

TDMA(Time Division Multiple Access) is a channel access scheme for shared medium networks. The shared frequency is divided into multiple time slots, some of which are assigned to a user for communication. Techniques for TDMA can be categorized into two classes: synchronous and asynchronous. Synchronization is not suitable for small scale networks because it is complicated and requires additional equipments. In contrast, in DESYNC, a biologically-inspired algorithm, the synchronization can be easily achieved without a global clock or other infrastructure overhead. However, DESYNC spends a great deal of time to complete synchronization and does not guarantee the maximum time to synch completion. In this paper, we propose a lightweight synchronization scheme, C-DESYNC, which counts the number of participating nodes with GP (Global Packet) signal including the information about the starting time of a period. The proposed algorithm is mush simpler than the existing synchronization TDMA techniques in terms of cost-effective method and guarantees the maximum time to synch completion. Our simulation results show that C-DESYNC guarantees the completion of the synchronization process within only 3 periods regardless of the number of nodes.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.2
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• pp.146-157
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• 2003

Our experience with Internet-based scientific collaboratories indicates that they need to be user-extensible, allow users to add tools and objects dynamically to workspaces, per mit users to move work dynamically between private and shared workspaces, and be easily accessible on the Internet. We present the software architecture of a development environment, called Collaboratory Builder's Environment(CBE), for building collaboratories to meet such needs. CBE provides user extensibility by allowing a collaboratory to be constructed as a collection of collaborative applets. To support dynamic reconfiguration of shared workspaces, CBE uses the metaphor of room that can contain applets, users, and arbitrary data objects. Rooms can be used not only for synchronous collaboration but also for asynchronous collaboration by supporting persistence. For the access over the Internet room participants are given different roles with appropriate access rights. A prototype of the model has been implemented in Java and can be run from a Java-enabled Web browser. The implemented system had been used by 95 users including 79 space scientists around the world in a scientific campaign that ran for 4 days. The usage evaluation of the campaign is also presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1369-1380
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• 2011

Most existing mobile distance learning systems are asynchronous ones that allow students to download lecture video and presentation material. However, there are a few synchronous real-time mobile distance learning systems that support slide, annotation, feedback from student, and lecture video and audio at the same time. These live mobile distance learning systems have an advantage of supporting real-time interaction between students and a lecturer thereby making students understand the lecture better. But, they also have a disadvantage in the sense that they don't allow students to experience the past lecture. This problem can be solved by recording and replaying lecture session. So far, there are few mobile distance learning systems that support session recording and replay. This paper presents a synchronous mobile distance learning system that supports video and audio, slide with annotation, and real-time feedback from students, as well as session recording and replay, which is not supported by the existing mobile distance learning systems. The evaluation of the system among students shows that 61.3% of them were satisfied while 3.2% weren't.