Sang Seok Lim

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—In this paper, a fast path planning method by optimization of a path graph for both efficiency and accuracy is proposed. A conventional quadtree-based path planning approach is simple, robust, and efficient. However, it has two limitations. The first limitation is that many small cells are required to represent obstacles because the positions and shapes of(More)
— In an attempt to expand Public Key Infrastructure (PKI) usage to a ubiquitous and mobile computing environment , we found that the deployment of the PKI on a resource constrained device such as 8 bit microprocessor leads to user-obstructive latency or an additional circuitry for the operations. To alleviate these limitations, we propose a new PKI-based(More)
Lightweight Directory Access Protocol (LDAP) is the predominant Internet directory access protocol and hence so is its use in the Public Key Infrastructure (PKI). This paper presents the design and implementation of LDAP component matching which enhances flexibility and security of the LDAP directory service when it is used for the PKI certificate(More)
As an integral part of the Web Services Security (WS-Security), directory services are used to store and access X.509 certificates. Lightweight Directory Access Protocol (LDAP) is the predominant directory access protocol for the Internet, and hence for the Web services. Values of LDAP attribute and assertion value syntaxes, though defined using ASN.1, are(More)
— This paper describes the issues and challenges in the design of an interoperable mobile security card for campus-wide ubiquitous services. The card holder becomes able to take pleasure of utilizing the ubiquitous services everywhere on a campus with high security. In order to realize the services, the card has been designed to have 1) a ZigBee module for(More)
LIMITED DISTRIBUTION NOTICE: This report has been submitted for publication outside of IBM and will probably be copyrighted if accepted for publication. It has been issued as a Research Report for early dissemination of its contents. In view of the transfer of copyright to the outside publisher, its distribution outside of IBM prior to publication should be(More)
This paper describes our effort to improve the performance of the connection management subsystem of the OpenLDAP directory server. Two proposed architec-tures, the multi-listener and the lightweight listener architectures will be described and compared to each other in this paper. This paper will also describe our effort to improve the synchronization of(More)