• Journal of the Korea Computer Graphics Society
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• v.24 no.3
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• pp.21-31
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• 2018

We introduces a system that enables fast and effective visualization of natural disaster data such as typhoons, tsunamis, floods, and flooding to help make informed decisions in disaster situations. Data containing disaster information consists of a few hundred megabytes to many tens and hundreds of gigabytes, which can not be handled by a PC. This system was implemented in the form of a client-server based service to generate and output results from high-performance servers. The server in a built-in, high-performance cluster handles client requests and sends the result of visualization to the client. Clients can receive the results in any form of images, videos, or 3D graphic model by specifying a desired time frame, effectively viewing the results with a user-friendly GUI.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.779-789
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• 2014

Utilizing smart phones based on android applications in the field of FA(Factory Automation) or PA(Production Automation) is being deployed actively. In general, MDM(Mobile Device Management) is a crucial infra-structure to build such a FA or PA environment. In this paper, we suggest an open mobile device management platform and implement its prototype. The developed prototype consists of three modules such as DMS(Device Management Server), FUMO(Firmware Update Management Object) and SCOMO(Software Component Management Object). In addition, we suggest a security module based on the concept of the EAP (Extensible Authentication Protocol) and the AES (Advanced Encryption Standard). The suggested security module's prototype is applied to guarantee the data integrity in the process of communicating among DMS, FUMO and SCOMO for the purpose of utilizing smart phones based on android applications in a FA field. We also evaluate the performance of the implemented security prototype. According to our simulation results, the implemented prototype has a good performance in a FA environment and can be utilized in the other FA, PA or OA(Office Automation) environment with guaranteeing the security.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1851-1858
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• 2004

The goal of this paper is to develop a production management system based on XML that exclusively applies to a production line of machine-parts. This paper aims to develop the related management modules and integrate them into the production management system based on XML technology. In terms of the implementation of the client/server database module, it develops the GUI application program that supports the communication between the subsystem that controls machine-parts and the server-side database. By developing the RPC emulator, the system remotely executes server module in the client GUI module. By developing the integration control module that integrates the independently executed modules, it controls the production management system that works as a single organic management system and by developing the POP system, it builds the information system of machine-parts performance records. This information system collects performance data through the serial port of the sensor attached to the machine-parts manufacturing machine, analyzes these data and display them in the GUI fashion, and immediately reflects them in production planning. And also it develops production management system based on XML by using XML technology.

• Journal of KIISE:Databases
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• v.29 no.1
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• pp.15-26
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• 2002

Most work on multimedia storage systems has assumed that client will be serviced using a round-robin strategy. The server services the clients in rounds and each client is allocated a time slice within that round. Furthermore, most such algorithms are evaluated on the basis of a tightly coupled cost function. This is the basis of well-known algorithm such as FCFS, SCAN, SCAN-EDF, etc. In this paper, we describe a scheduling module called Request Unifier(RU) that takes as input, a set of client request, and a set of constraints on the desired performance such as client waiting time or maximum disk bandwidth, and a cost function. It produces as output a Unified Read Request(URR), telling the storage server which data items to read and when these data items to be delivered to the clients. Given a cost function, a URR is optimal if there is no other URR satisfying the constraints with a lower cost. We present three algorithms in this paper that can accomplish this kind of request merging and compare their performance through an experimental evaluation.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.4
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• pp.217-224
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• 2010

Nowadays, people perform their tasks anywhere anytime using their mobile devices. For this reason, data synchronization (DS) between mobile devices and a central server has become one of the most essential technologies in mobile environments. Currently, several mobile DS protocols are proposed and used. However, the existing DS protocols cannot guarantee interoperability between them. To solve the problem, an embedded DS gateway has been developed in our previous study. The gateway runs on a Windows Mobile-based emulator. It converts data on a mobile device into common data specified by OMA DS standard protocol and vice versa. The embedded gateway has been built to support the OMA DS standard protocol. In order to verify that the embedded gateway conforms to the OMA DS standard protocol, two kinds of OMA conformance tests have to be conducted - interoperability test with an OMA DS-based server and conformance test with SCTS (SyncML Conformance Test Suit). In this paper, some parts of the gateway previously built are modified and the modified gateway is installed on a Windows Mobile-based smart phone. And the interoperability test and the conformance test with the SCTS are conducted. The results of the tests show that the embedded DS gateway operates properly on the Windows Mobile-based smart phone and that the gateway passes the tests, verifying its conformity to the OMA DS standard protocol. In addition, DS performance tests show that DS delay times between a real smart phone and a DS server increase gently as the number of DS data increases. In other words, the embedded DS gateway built in this paper can be used for a real smart phone at a reasonable performance cost.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.270-273
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• 2015

In shipbuilding and marine industry, engineering and design software solutions have upgraded from the original 2D schematic data based CAD system to a modern 3D drawing-based system. Due to the fact that the massive amount of data usage in real time and data volumes of various engineering models including graphic data have increased, several problems such as lack of server resources and improper handling of 3D drawings have been raised. Besides, increasing the number of session connections per server can cause deterioration of server performance. Recently, increasing the yard's sophisticated design capabilities highlighted the need to develop engineering and design system which would not only overcome the network performance issues, but would provide efficient collaborative design environment. This paper presents an overview of the framework for collaborative engineering design system based on the virtual application (Citrix XenApp 6.5)and acceleration hardware technology of 3D graphics (NVIDIA GRID K2 solution).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.57-64
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• 2012

Multiplayer, real-time games are a kind of soft real-time systems because a game server has to respond to requests from many clients within specified time constraints. Client events have different timeliness and consistency requirements according to their nature in the game world. These requirements lead to different priorities on CPU processing. Events can be divided into different groups, depending on their consistency degree and priority. To handle these events with different priority and meet their timing constraints, we propose a priority-based group task scheduling policy in this paper. The number of clients or events requested by each client may be increased temporarily. In the presence of transient overloading, the game server needs to allocate more CPU bandwidth to serve an event with the higher priority level preferentially. The proposed scheduling policy is capable of enhancing real-time performance of the entire system by maximizing the number of events with higher priority completed successfully within their deadlines. The performance of this policy is evaluated through extensive simulation experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.89-95
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• 2016

In this paper, we propose a locker system that can remotely control and manage locker. The main features of the proposed system are follows. First, connect the locker with server and then open the locker after passing through the certification process in server. Second, locker manager can more systematically manage a locker by using locker management system based on smart phone. Third, provide an instant locker for temporary using lockers to increase the ease of use. Fourth, unlike traditional analog locker, can support better security by using authentication process and log data. Performance evaluation is performed via simulation by making the dummy model. The results of performance evaluation show the proposed system can support efficiently the locker management.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.721-732
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• 2000

Multimedia communication systems require not only high-performance computer hardwares and high-speed networks, but also a buffer management mechanism to process many data efficiently. Two buffer handling methods, Push and Pull, are commonly used. In the Push method, a server controls the flow of dat to a client, while in the Pull method, a client controls the flow of data from a server. Those buffering schemes can be applied to the data transfer between the packet receiving buffer, which receives media data from a network server, and media playout devices, which play the recived media data. However, the buffer management mechanism in client-sides mainly support either one of the Push or the Pull method. Consequently, they have some limitations to support various media playout devices. Futhermore, even though some of them support both methods, it is difficult to use since they can't provide a unified structure. To resolved these problems, in this paper, we propose an efficient and flexible Push/Pull buffer management mechanism at client-side. The proposed buffer management scheme supports both Push and Pull method to provide various media playout devices and to support buffering function to absorb network jitter. The proposed scheme can support the various media playback devices using a single buffer space which in consequence, saves memory space compared to the case that a client keeps tow types of buffers. Moreover, it facilitates the single buffer as a mechanism for the absorbing network jitter effectively and efficiently. The proposed scheme has been implemented in an existing multimedia communication system, so called ISSA (Integrated Streaming Service Architecture), and it shows a good performance result compared to the conventional buffering methods in multimedia communication environments.

• Journal of KIISE:Databases
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• v.29 no.6
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• pp.477-491
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• 2002

The broadcast environment has asymmetric communication aspect that is typically much greater communication bandwidth available from server to clients than in the opposite direction. In addition, mobile computing systems generate mostly read-only transactions from mobile clients for retrieving different types of information such as stock data, traffic information and news updates. Since previous concurrency control protocols, however, do not consider such a particular characteristics, the performance degradation occurs when previous schemes are applied to the broadcast environment. In this paper, we propose optimistic concurrency control based on timestamp interval for broadcast environment. The following requirements are satisfied by adapting weak consistency that is the appropriate correctness criterion of read-only transactions: (1) the mutual consistency of data maintained by the server and read by clients (2) the currency of data read by clients. We also adopt the timestamp Interval protocol to check the weak consistency efficiently. As a result, we improved a performance by reducing unnecessary aborts and restarts of read-only transactions caused when global serializability was adopted.