• Journal of KIISE:Computing Practices and Letters
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• v.9 no.1
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• pp.95-99
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• 2003

In addition to wired communication technology, wireless communication technology has had communication revolution nowadays. Bluethooth technology carries out data/voice communication within pico-net. Nowadays the various services are supported by access network connected to public network. This paper presents implementation of bluetooth protocol analyser which simulates bluetooth protocol. MS window98 and visual C are used for development environment and application program is operated over the firmware loaded on the bluetooth device connected to the PC through UART which of the maximum transmission rate is 115kbps because transmission rate less than 20kbps affects rarely the performance. The performance analysis on the propose system is carried out as simulating the signalling information for the voice test and the traffics between two bluetooth systems for file transfer. The throughput analysis for file transfer service and call processing capacity for voice service are considered as performance analysis parameters. File access time is very important parameter and throughput is 13 kbps in case breakpoint time to file access is 0.04sec. Also call processing time is about 16.6ms in case of communication with the headset. The performance analysis of simulation results satisfies with bluetooth device development.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.493-504
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• 2007

With the advance and proliferation of computer and wireless network technology, it is common to access to network through the wireless network using mobile device. The ratio of using the streaming media out of many applications through the network is increasing not only in the wired network but also in the wireless network. The streaming media is much bigger than other contents and requires more network bandwidth to communicate and more computing resources to process. However the mobile devices have relatively poor computing resource and low network bandwidth. If the streaming media service is provided for mobile devices without any consideration about the network bandwidth and computing power, it is difficult for the client to get the service of high quality. Since especially mobile devices are supported with very limited energy capacity from the battery, the streaming media service should be adjusted to the varying energy state of mobile devices to ensure the complete playback of streaming media. In this paper, we propose a new method to guarantee the complete playback time of the streaming media for the mobile clients by dynamically controlling transmitted frame rate to the client according to the estimated available time of mobile device using battery model reflecting the characteristic of the battery. Since the proposed method controls the number of frames transmitting to the client according to the energy state of the mobile device, the complete playback time is guaranteed to mobile clients.

• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.103-115
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• 2007

The vulnerability issue on IEEE 802.1x wireless LAN has been permits the malicious attack such as Auth/Deauth flooding more serious rather than we expected. Attacker can generate huge volume of malicious traffic as the same methods on existing wired network. The objective of wireless IP Traceback is to determine the real attack sources, as well as the full path taken by the wireless attack packets. Existing IP Traceback methods can be categorized as proactive or reactive tracing. But, these existing schemes did not provide enhanced performance against DoS attack on wireless traffic. In this paper, we propose a 'TTL based advanced Packet Marking' mechanism for wireless IP Packet Traceback with wireless Classification function. Proposed mechanism can detect and control DoS traffic on AP and can generate marked packet for reconstructing on the real path from the non-spoofed wireless attack source, by which we can construct secure wireless network based on AP with enhance traceback performance.

• Journal of the Korea Society of Computer and Information
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• v.13 no.2
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• pp.185-191
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• 2008

Most threats of WLAN are easily caused by attackers who access to the radio link between STA and AP, which involves some Problems to intercept network communications or inject additional messages into them. In comparison with wired LAN, severity of wireless LAN against threats is bigger than the other networks. To make up for the vulnerability of wireless LAN, it needs to use the Intrusion Detection System using a powerful intrusion detection method as SVM. However, due to classification based on calculating values after having expressed input data in vector space by SVM, continuous data type can not be used as any input data. In this paper, therefore, we design the IDS system for WLAN by tuning with SVM and data-mining mechanism to defend the vulnerability on certain WLAN and then we demonstrate the superiority of our method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.748-751
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• 2004

In this paper, we discuss about wireless Internet security. The past few years have seen unprecedented growth in the number of wireless user, applications, and network access technologies. Wireless Internet is similar to wired internet, but it has some constrained wireless environment. So many internet technologies for wireless are developing now. There are WAP(Wireless Application Protocol) and WPKI. WAP(now version 2.0) is a protocol specification for wireless communication networks. it provides an application framework and network protocols for wireless devices such as mobile telephones, PDAs and internet technologies. In this paper some analysis of security(e.g. digital signature or encryption) for wireless internet are performed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.5
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• pp.47-57
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• 2006

Mobile Ad-hoc networks have various implementation constraints such as infrastructure-free, no trusted authority, node mobility, and the limited power and small memory of mobile device. And just like wired networks, various security issues such as authentication, confidentiality, integrity, non-repudiation, access control, availability and so on have been arisen in mobile Ad-hoc networks. But we focus on authentication of these security issues because it is quitely affected by the characteristics of networks. In this paper, we propose the authentication protocol that can limit the size of certificate repository as $log_2N$ and assures to make a trusted certificate path from one node to another, adopting the concept of Hamming distance. Particularly, our protocol can construct a trusted certificate path in spite of decreasing or increasing the number of nodes in mobile Ad-hoc network.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.6
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• pp.55-65
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• 2011

Recently, use of cloud computing service is dramatically increasing due to wired and wireless communications network diffusion in a field of high performance Internet technique. Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. In a view of digital forensic investigation, it is difficult to obtain data from cloud computing service environments. therefore, this paper suggests analysis method of AWS(Amazon Web Service) and Rackspace which take most part in cloud computing service where IaaS formats presented for data acquisition in order to get an evidence.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.278-283
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• 2000

As information communication technology developed we could check our blood pressure, pulsation electrocardiogram, SpO2 and blood test easily at home. To check our health at ordinary times is able though interlocking the house medical instrument with the wireless public data network This service will help the inconvenience to visit the hospital everytime and will save the individual's time and cost. In each house an organism data which is detected from the human body will be transmitted to the distance hospital and will be essentially applied through wireless public data network The medical information transmit system is utilized by wireless close range network It would transmit the obtained organism signal wirelessly from the personal device to the main center system in the hospital. Remote telemetry system is embodied by utilizing wireless media access protocol. The protocol is embodied by grafting CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) protocol falling mode which is standards from IEEE 802.11. Among the house care telemetry system which could measure blood pressure, pulsation, electrocardiogram, SpO2 the study embodies the ECC(electrocardiograph) measure part. It within the ECC function into the movable device and add 900㎒ band wireless public data interface. Then the aged, the patients even anyone in the house could obtain ECG and keep, record the data. It would be essential to control those who had a health-examination heart diseases or more complicated heart diseases and to observe the latent heart disease patient continuously. To embody the medical information transmit system which is based on wireless network. It would transmit the ECG data among the organism signal data which would be utilized by wireless network modem and NCL(Native Control Language) protocol to contact through wireless network Through the SCR(Standard Context Routing) protocol in the network it will be connected to the wired host computer. The computer will check the recorded individual information and the obtained ECC data then send the correspond examination to the movable device. The study suggests the medical transmit system model utilized by the wireless public data network.

• The KIPS Transactions:PartC
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• v.18C no.4
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• pp.265-278
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• 2011

The objective of this paper is to analyze and characterize end-to-end packet statistics after modeling and simulation of WiFi (IEEE 802.11g) and WiMAX (IEEE 802.16e) of a virtual wireless network using OPNET Modeler Wireless Suite. Wireless internal and external network simulators such as Remcom's Wireless InSite Real Time (RT) module, WinProp: W-LAN/Fixed WiMAX/Mobile WiMAX, and SMI system, are designed to consider data transfer rate based on wireless propagation signal strength. However, we approached our research in a different perspective without support for characteristic of these wireless network simulators. That is, we will discuss the purpose of a visual analysis for these packets, how to receive each point packets (e.g., wireless user, base station or access point, and http server) through end-to-end virtual network modeling based on integrated wired and wireless network without wireless propagation signal strength. Measuring packet statistics is important in QoS metric analysis among wireless network performance metrics. Clear packet statistics is an especially essential metric in guaranteeing QoS for WiMAX users. We have found some interesting results through modeling and simulation for virtual wireless network using OPNET Modeler Wireless Suite. We are also able to analyze multi-view efficiency through experiment/observation result.

• Progress in Medical Physics
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• v.14 no.2
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• pp.124-130
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• 2003

Currently, as a consequence of PACS (Picture Archiving Communication System) implementation many hospitals are replacing conventional film-type interpretations of diagnostic medical images with new digital-format interpretations that can also be saved, and retrieve However, the big limitation in PACS is considered to be the lack of mobility. The purpose of this study is to determine the optimal communication packet size. This was done by considering the terms occurred in the wireless communication. After encoding medical image using JPGE2000 image compression method, This method embodied auto-error correction technique preventing the loss of packets occurred during wireless communication. A PC class server, with capabilities to load, collect data, save images, and connect with other network, was installed. Image data were compressed using JPEG2000 algorithm which supports the capability of high energy density and compression ratio, to communicate through a wireless network. Image data were also transmitted in block units coeded by JPEG2000 to prevent the loss of the packets in a wireless network. When JPGE2000 image data were decoded in a PUA (Personal Digital Assistant), it was instantaneous for a MR (Magnetic Resonance) head image of 256${\times}$256 pixels, while it took approximately 5 seconds to decode a CR (Computed Radiography) chest image of 800${\times}$790 pixels. In the transmission of the image data using a CDMA 1X module (Code-Division Multiple Access 1st Generation), 256 byte/sec was considered a stable transmission rate, but packets were lost in the intervals at the transmission rate of 1Kbyte/sec. However, even with a transmission rate above 1 Kbyte/sec, packets were not lost in wireless LAN. Current PACS are not compatible with wireless networks. because it does not have an interface between wired and wireless. Thus, the mobile JPEG2000 image viewing system was developed in order to complement mobility-a limitation in PACS. Moreover, the weak-connections of the wireless network was enhanced by re-transmitting image data within a limitations The results of this study are expected to play an interface role between the current wired-networks PACS and the mobile devices.