Young Man Kim

Bio: Young Man Kim is an academic researcher from Ohio State University. The author has contributed to research in topics: Packet switching & Fast packet switching. The author has an hindex of 5, co-authored 7 publications receiving 126 citations. Previous affiliations of Young Man Kim include Mitsubishi.

Efficient signature file methods for text retrieval

Abstract: Signature files have been studied extensively, as an access method for textual databases. Many approaches have been proposed for searching signatures files efficiently. However, different methods make different assumptions and use different performance measures, making it difficult to compare their performance. In this paper, we study three basic methods proposed in the literature, namely, the indexed descriptor file, the two-level superimposed coding scheme, and the partitioned signature file approach. The contribution of this paper is two-fold. First, we present a uniform analytical performance model so that the methods can be compared fairly and consistently. The analysis shows that the two-level superimposed coding scheme, if stored in a transposed file, has the best performance. Second, we extend the two-level superimposed coding method into a multilevel superimposed coding method, we obtain the optimal number of levels for the multilevel method and show that for databases with reasonable size the optimal value is much larger than 2, which is assumed in the two-level method. The accuracy of the analytical formula is demonstrated by simulation. >

KSMINs: knockout switch-based multistage interconnection networks for high-speed packet switching

Abstract: We propose knockout switch-based multistage interconnection networks (KSMINs) for fast packet switching, combining the well-known knockout switch and the concept of multistage interconnection networks. The main objective is to reduce the severe pin requirements of large knockout switches through a phased address filtering. We present an approximate Markov-chain model of KSMINs to study the performance of KSMINs with different numbers of address-filtering phases. The model is shown to be accurate within 5% for all the cases considered and within 20% for the meaningful cases of the buffer sizes /spl ges/4. For the (256/spl times/256) KSMIN, two-phase address filtering based on the (16/spl times/16) knockout switches is shown to perform very closely to the single-stage knockout switch for a reduced hardware cost. >

KSMINs: knockout switch based multistage interconnection networks for high-speed packet switching

Abstract: Knockout-switch-based multistage interconnection networks (KSMINs) for fast packet switching, combining the well-known knockout switch and the concept of multistage interconnection networks are proposed. The main objective is to reduce the severe pin requirements of large knockout switches through phased address filtering. An approximate Markov chain model of KSMINs is presented to study the performance of KSMINs with different numbers of address filtering phases. The model is shown to be accurate within 5 % for all the cases considered, and within 2 % for the meaningful cases of the buffer sizes >or=4. For the (256*256) KSMIN, two-phase address filtering based on the (16*16) knockout switches is shown to perform very closely to the single-stage knockout switch for a much-reduced hardware cost. >

Performance analysis of buffered banyan networks under nonuniform traffic

Abstract: This paper presents a new analytic model for buffered Banyan networks. The new model is the most general one in the current literature, and allows the traffic pattern, the buffer size, and the switch size as input parameters among other things. The main motivation of the development of the new model was to provide an analytical tool to evaluate the performances of buffered Banyan networks under nonuniform traffic patterns, which mostly remained unknown except for some very limited cases. With the new model, we measured network performances for several important memory access patterns occurring in the parallel loop execution in multiprocessors. The performance results and the implications of the results on data storage schemes are discussed.

Inverted files for text search engines

Abstract: The technology underlying text search engines has advanced dramatically in the past decade. The development of a family of new index representations has led to a wide range of innovations in index storage, index construction, and query evaluation. While some of these developments have been consolidated in textbooks, many specific techniques are not widely known or the textbook descriptions are out of date. In this tutorial, we introduce the key techniques in the area, describing both a core implementation and how the core can be enhanced through a range of extensions. We conclude with a comprehensive bibliography of text indexing literature.

Recent Advances in Graph Partitioning

Abstract: We survey recent trends in practical algorithms for balanced graph partitioning, point to applications and discuss future research directions.

Keyword Search on Spatial Databases

Abstract: Many applications require finding objects closest to a specified location that contains a set of keywords. For example, online yellow pages allow users to specify an address and a set of keywords. In return, the user obtains a list of businesses whose description contains these keywords, ordered by their distance from the specified address. The problems of nearest neighbor search on spatial data and keyword search on text data have been extensively studied separately. However, to the best of our knowledge there is no efficient method to answer spatial keyword queries, that is, queries that specify both a location and a set of keywords. In this work, we present an efficient method to answer top-k spatial keyword queries. To do so, we introduce an indexing structure called IR2-Tree (Information Retrieval R-Tree) which combines an R-Tree with superimposed text signatures. We present algorithms that construct and maintain an IR2-Tree, and use it to answer top-k spatial keyword queries. Our algorithms are experimentally compared to current methods and are shown to have superior performance and excellent scalability.

Optimizing bitmap indices with efficient compression

Abstract: Bitmap indices are efficient for answering queries on low-cardinality attributes. In this article, we present a new compression scheme called Word-Aligned Hybrid (WAH) code that makes compressed bitmap indices efficient even for high-cardinality attributes. We further prove that the new compressed bitmap index, like the best variants of the B-tree index, is optimal for one-dimensional range queries. More specifically, the time required to answer a one-dimensional range query is a linear function of the number of hits. This strongly supports the well-known observation that compressed bitmap indices are efficient for multidimensional range queries because results of one-dimensional range queries computed with bitmap indices can be easily combined to answer multidimensional range queries. Our timing measurements on range queries not only confirm the linear relationship between the query response time and the number of hits, but also demonstrate that WAH compressed indices answer queries faster than the commonly used indices including projection indices, B-tree indices, and other compressed bitmap indices.

Survey of ATM switch architectures

Abstract: For reasons of economy and flexibility, BISDN (Broadband Integrated Services Digital Network) is expected to replace existing application-oriented communication networks. ATM (Asynchronous Transfer Mode) is a high-speed packet-switching technique that has emerged as the most promising technology for BISDN. Since early 1980s, a large number of architectures have been proposed for ATM switching. In this paper, we present a descriptive survey of ATM switch architectures, with emphasis on electronic space-division point-to-point switches.