• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.701-708
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• 2005

The mobility prediction algorithm and the channel reservation scheme have been reported as an effective means to provide QoS guarantees and the efficient resource reservation in wireless networks. Among these prediction algorithms, the recently proposed Detailed-ZMHB algorithm makes use of the history of the user's positions within the current cell to predict the next cell, which provides the better prediction accuracy than the others. The handoff prioritizing schemes are proposed to provide improved performance at the expense of an increase in the blocking probability of new calls. In the soft handoff of the CDMA systems, a mobile can communicate via two adjacent cells simultaneously for a while before the actual handoff takes place. In this paper, we propose a new channel reservation scheme making use of the user mobility pattern information in order to reduce the call dropping probability. Our results show that the proposed scheme gives about 67.5-71.1$\%$ lower call dropping probability, compared to the existing scheme.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.617-622
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• 2005

Lately, the MANET research has focused on providing routing services with security and previous schemes have been proposed for detecting malicious nodes in a MANET. However, they still include some problems which malicious nodes cannot be found when they falsely report other nodes as malicious. Accordingly, we propose a novel and efficient scheme for detecting malicious nodes using report messages and a report table which is consisted of node ID both for suspecting and reporting when the malicious nodes behave normally during the route discovery, but the other hand they drop and modify packets, or falsely report other nodes as malicious during the data transmission. Our proposed scheme is applicable to not only DSR but aiso AODV. And we provide some simulation results of our proposed scheme by comparing general AODV with our proposed scheme. Simulation results show that our Proposed scheme outperforms general AODV in terms of average packet loss ratio and packet delivery ratio.

• The KIPS Transactions:PartC
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• v.12C no.5 s.101
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• pp.757-764
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• 2005

With the increasing service Qualify and security in the Mobile Internet Diameter technology based on the AAAv6 is being used in the user authentication. But there are some Problems on the authentication Procedures of the Diameter in which the security falls down from a loaming service or Internet transmission course. We combine it with the cipher algorithm like EAP-MD5 and accomplish a user authentication processing. If we want to supply the user authentication with the mobility among domains by AAAv6-based Diameter, we need the efficient capacity allocation among AAA attendent, AAAv, AhAb, AAAh, HA servers in the AAAv6. Therefore in this paper, we propose to make the authentication capacity index to carry out user authentication ability by analyzing an EAP-MD5S server capacity model of AAAv6 authentication models for users with mobility among domains, and to find the optimized condition for the AAAv6 capacity by the index.

• The KIPS Transactions:PartC
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• v.14C no.3 s.113
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• pp.305-312
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• 2007

In this paper, we present a received signal strength (RSS) prediction model to timely Initiate link layer triggers for fast handoff in a wireless LAN system. Noting that the distance between a mobile terminal and an access point is not changed abruptly in a short time interval, an adaptive RSS predictor based on a stationary time series model is proposed. RSS data obtained from ns-2 simulations are used to identity the time series model and verify the predictability of the RSS data. The results suggest that an autoregressive process of order 1 (AR(1)) can be used to represent the measured RSSs in a short time interval and predict at least 1-step ahead RSS with a high confidence level.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.5-15
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• 2015

Electronic transactions have been increasing with the development of the high-speed Internet and wireless communication. However, in recent years financial corporations and mobile carriers were attacked by hackers. And large numbers of privacy information have been leaked. In particular, in the case of credit card information can be misused in the online transaction, and the damage of this given to cardholder. To prevent these problems, it has been proposed to use a virtual card number instead of the actual card number. But it has security vulnerability and requires additional security infrastructure. In this paper, we analyzed the proposed virtual card number schemes. and we propose a new virtual credit card number scheme. In the newly proposed scheme, cardholder generates a key pair (public key/private key) and pre-register public key to the issuer. then, cardholder can pay no additional security infrastructure while still efficiently satisfy the security requirements.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.2
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• pp.97-103
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• 2006

This paper designs mono block type with rotating high power radiography x-ray generator and studies 16kW X-ray generator possible to adapt hospital mobile radiography and industrial X-ray equipment and design. This equipment uses rotating anode type x-ray tube at high voltage generator to generate x-ray and adds rotor operating circuit to operate rotor of x-ray tube. The size of high voltage transformer and high voltage generator is minimized by high voltage high frequency inverter has 100kHz switching frequency. Also this paper shows result of x-ray tube voltage and tube current correspond to variable load.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.1
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• pp.31-42
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• 2017

Thumbnail, the small sized graphic file such as JPEG or GIF, serves to help the users to be recognized as a rapidly helps to make it easier recognize while browsing the large sized graphic file. Gallery application, which is installed in a later version of the 4.4.x(Kitkat) Android smartphone records the generated time of graphic file in thumbnail metadata. Thumbnail can be used to draw up the timeline of user action about user's action such as creation, modification, deletion with original graphic file analysis. Also, take advantage of the features thumbnails are stored sequentially in a single thumbcache file, even if the thumbcache is deleted, we can restore the thumbnails. This paper illustrates the feature of thumbnail created by Android OS basic gallery app and methods for utilization in digital forensics.

• The KIPS Transactions:PartA
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• v.11A no.1
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• pp.37-48
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• 2004

The SyncML, the standard synchronization protocol, supports the synchronization of various application services between a client and a server such as an address book, a calendar. Even with this standard protocol, SyncML application developers usually spend a long time and efforts implementing service specific logics and databases. This paper designed and implemented the SDE(Service Development Environment) which is an integrated development environment for SyncML server developers to develop an application service rapidly and correctly. The SDE consists of two components i.e., the Sync Library and the SEG(Sync Engine Generator) tool. To prove the applicability of this study we implemented a SyncML server by using the SDE and also carried out the correctness tests and the performance test. We hope this system helps developers implement mobile application services more efficiently.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.129-138
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• 2007

AAA(Aluthentieation, Authorization, Accounting) protocol is an information securitv technology that offer secure and reliable user Authentication, Authorization, Accounting function systematically in various services. protocol and wireless network work as well as win network. Currently IETF(Internet Engineering Task Force) AAA Working Group deal with about AAA protocol and studying with activity, But, recently it exposing much problems side to user's anonymity and privacv violation. Therefore, in this paper, AAAH(Home Authentication Server) authenticaters Mobile device, after that, use ticket that is issued from AAAH even if move to outside network and can be serviced offering authentication in outside network without approaching by AAAH, Also, we study mechanism that can offer user's privacy and anonymousness to when use service. Our mechanism is using Time Synchronization OTP and focusing authentication and authorization. Therefore, our mechanism is secure from third party attack and offer secure and effective authentication scheme. Also only right user can offer services by using ticket. can reduce signal and reduce delay of message exchanged, can offer persistent service and beighten security and efficiency.

• The KIPS Transactions:PartA
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• v.14A no.5
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• pp.279-286
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• 2007

The need of contents adaptation in ubiquitous environments is growing to support multiple target platforms for 3D graphics contents. Since 3D graphics deal with a large data set md a high performance, a service adaptation for context changing is required to manipulate graphics contents with a more complicated method in multiple devices such as desktops, laptops, PDAs, mobile phones, etc. In this paper, we suggest a new notion of service adaptation middleware based on service rendering algorithm, which provides a flexible and customized service for user-centric 3D graphics contents. The service adaptation middleware consists of Service Adaptation(SA) for analyzing environments and Service Rendering(SR) for reconfiguring customized services by processing customized data. These adaptation services are able to intelligently and dynamically support the same computer graphics contents with good quality, when user environments are changed.