Byung Suk Lee

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Pitch tracking algorithms have a long history in various applications such as speech coding and extracting information, as well as other domains such as bioacoustics and music signal processing. While autocorrelation is a useful technique for detecting periodicity, autocorrelation peaks suffer ambiguity, leading to the classic “octave error” in pitch(More)
There have been several techniques proposed for improving the performance of main-memory spatial indexes, but there has not been a comparative study of their performance. In this paper we compare the performance of six main-memory R-tree variants: R-tree, R*-tree, Hilbert R-tree, CR-tree, CR*tree, and Hilbert CR-tree. CR*-trees and Hilbert CR-trees are(More)
One of the approaches for integrating object-oriented programs with databases is to instantiate objects from relational databases by evaluating view queries. In that approach, it is often necessary to evaluate some joins of the query by left outer joins to prevent information loss caused by the tuples discarded by inner joins. It is also necessary to lter(More)
Reservoir sampling is a well-known technique for sequential random sampling over data streams. Conventional reservoir sampling assumes a fixed-size reservoir. There are situations, however, in which it is necessary and/or advantageous to adaptively adjust the size of a reservoir in the middle of sampling due to changes in data characteristics and/or(More)
As XML has become popular as a document standard in the World Wide Web, a lot of research has been done on the XML storage systems, which store and manage XML documents using existing DBMSs. Most of the research activities, however, assume a relational DBMS instead of an object-oriented/object-relational (OO/OR) DBMS, which offers more powerful modeling(More)
When we design an object-oriented database schema, we need to normalize object classes as we do for relations when designing a relational database schema. However, the normalization process for an object class cannot be the same as that of a relation, because of the distinct characteristics of an object-oriented data model such as complex attributes,(More)
Web caching is an important technique for accelerating web applications and reducing the load on the web server and the network through local cache accesses. As in the traditional data caching, web caching poses the wellrecognized problem of maintaining cache consistency. Web caching, however, has the leeway of delaying the refreshment of caches when the(More)
In stream join processing with limited memory, uniform random sampling is useful for approximate query evaluation. In this paper, we address the problem of reservoir sampling over memory-limited stream joins. We present two sampling algorithms, Reservoir Join-Sampling (RJS) and Progressive Reservoir Join-Sampling (PRJS). RJS is designed straightforwardly by(More)
Accurately determining a user's floor location is essential for minimizing delays in emergency response. This paper presents a floor localization system intended for emergency calls. We aim to provide floor-level accuracy with minimum infrastructure support. Our approach is to use multiple sensors, all available in today's smartphones, to trace a user's(More)