Heung Seok Jeon

A Term Cluster Query Expansion Model Based on Classification Information in Natural Language Information Retrieval

A natural language information retrieval system ranks related documents according to criteria based on user query keywords and document similarities. However, many efforts have been made to make more useful query keywords because users do not use many keywords in their natural language search query when retrieving information on the Web. Because a keyword does not provide much information, however, relevance feedback is generally used to complement the weakness of general retrieval methods. This paper proposes a term cluster query expansion model based on classification information of retrieved documents. This model generates classification information from the upper ranked n documents retrieved by retrieval system. On the basis of the extracted classification information, the term cluster (m) that represents each group is generated, and then the model allows user to select term cluster that corresponds to user information needs. The query keywords are expanded by using a relevance feedback algorithm based on the selected classification information. As a result of the experiments with test collection, the retrieval effectiveness was improved by 13.2% compared to the initial query when the Rocchio method was used.

Practical buffer cache management scheme based on simple prefetching

Many replacement and prefetching policies have recently been proposed for buffer cache management. However, many real operating systems, including GNU/Linux, generally use the simple least recently used (LRU) replacement policy with prefetching being employed in special situations such as when sequentiality is detected. In this paper, we propose the SA-W2R scheme that integrates buffer management and prefetching, where prefetching is done constantly in aggressive fashion. The scheme is simple to implement making it a feasible solution in real systems. In its basic form, for buffer replacement, it uses the LRU policy. However, its modular design allows for any replacement policy to be incorporated into the scheme. For prefetching, it uses the LRU-one block lookahead (LRU-OBL) approach, eliminating any extra burden that is generally necessary in other prefetching approaches. Implementation studies based on the GNU/Linux show that the SA-W2 R performs better than the GNU/Linux with a maximum increases of 23% for the workloads considered

A practical method for the detection of freezing of gait in patients with Parkinson’s disease

Purpose Freezing of gait (FOG), increasing the fall risk and limiting the quality of life, is common at the advanced stage of Parkinson’s disease, typically in old ages. A simple and unobtrusive FOG detection system with a small calculation load would make a fast presentation of on-demand cueing possible. The purpose of this study was to find a practical FOG detection system. Patients and methods A sole-mounted sensor system was developed for an unobtrusive measurement of acceleration during gait. Twenty patients with Parkinson’s disease participated in this study. A simple and fast time-domain method for the FOG detection was suggested and compared with the conventional frequency-domain method. The parameters used in the FOG detection were optimized for each patient. Results The calculation load was 1,154 times less in the time-domain method than the conventional method, and the FOG detection performance was comparable between the two domains (P=0.79) and depended on the window length (P<0.01) and dimension of sensor information (P=0.03). Conclusion A minimally constraining sole-mounted sensor system was developed, and the suggested time-domain method showed comparable FOG detection performance to that of the conventional frequency-domain method. Three-dimensional sensor information and 3–4-second window length were desirable. The suggested system is expected to have more practical clinical applications.

A Resolving of Word Sense Ambiguity Using Two-level Document Ranking Method in Information Retrieval

The resolving of word sense ambiguity is one of important problem in information retrieval. Words can have several meanings or senses, and a use of the word out of context is ambiguous between these senses. Mutual information is a relation measure which represents relation between a word and another word. To disambiguate the lexical ambiguity in the retrieved documents, we re-evaluate relation between terms of retrieved document and terms of query. In this paper, we discuss a resolving of word sense ambiguity of information retrieval that is two-level document ranking method using mutual information. At the first level, we retrieve documents based on an automatically constructed keyword index. At the second-level, we reorder the retrieved documents using mutual information. We show that our method provides a resolving of word sense ambiguity in the retrieved documents. Also, we analyze several formulas and found a formula which to disambiguate the word sense ambiguity in the retrieved documents.

The roles of ontology and metadata registry for interoperable databases

In order to make multiple autonomous databases to interoperate effectively, semantic heterogeneities have to be detected and resolved Another difficulty is that users can be allowed to handle information easily from different heterogeneous databases that refer to the same real-world entity To solve these problems, in this paper, I present an information integration system for interoperable databases using metadata registry and ontology A metadata registry is a place to keep facts about characteristics of data that are necessary for data sharing and exchange in a specific domain An ontology defines concepts and relations among concepts The purpose of the proposed architecture is to define an information integration model, which combines characteristics of both standard specification of metadata registry and functionality of ontology for the concepts and relations.

Developing an integrated retrieval system for Web databases

The majority of the information on the Web is dynamic content provided through linkups with databases. Therefore, we need an integrated information retrieval system that can effectively combine and access a vast resource of dynamic web contents linked with databases.

Virtual fences for controlling livestock using satellite-tracking and warning signals

In this paper we describe our “Virtual fencing” project. This project is a method of controlling animals without ground-based fencing. Control occurs by altering an animals behavior through one or more sensory cues administered to the animal after it has attempted to penetrate an electronically-generated boundary. This boundary can be of any geometrical shape, and though unseen by the eye. Am animal is detected by a computer system worn by the animal which we refer to as a Smart Collar. Each animal in the herd is given a smart collar consisting of a global positioning system (GPS), XBee communication module and mp3 player.

Fast Path Planning Algorithm for Mobile Robot Navigation

Mobile robots use an environment map of its workspace to complete the surveillance task. However grid-based maps that are commonly used map format for mobile robot navigation use a large size of memory for accurate representation of environment. In this reason, grid-based maps are not suitable for path planning of mobile robots using embedded board. In this paper, we present the path planning algorithm that produce a secure path rapidly. The proposed approach utilizes a hybrid map that uses less memory than grid map and has same efficiency of a topological map. Experimental results show that the fast path planning uses only 1.5% of the time that a grid map based path planning requires. And the results show a secure path for mobile robot.

R-Map: A hybrid map created by maximal rectangles

While there has been substantial research on the integration of grid-based and topological maps, no previous approach, to our knowledge, has considered constructing hybrid maps applying the maximal empty rectangle problem found in computational geometery. We propose a hybrid map, R-Map, which is built by extracting a topological information out of a grid map by a simple rule; Find the largest free rectangular area recursively in a given area. The experiment results show R-Map can produce a good representation of an environment, efficiently reducing space complexity with a limited number of rectangles and clearly showing free and non-free space.

A practical coverage algorithm for intelligent robots with deadline situations

Coverage algorithm is one of the core technologies required for intelligent robots such as cleaning robots, harvesting robots, painting robots and lawn mowing robots. Although many smart coverage algorithms have been proposed, to the best of our knowledge, all of them make the same assumption that they have sufficient time to cover the entire target area. However, the time to completely cover the whole target area may not always be available. Therefore, in this paper, we propose another new coverage scheme, which we call the DmaxCoverage algorithm, that decides the coverage path by considering the deadline for coverage. This approach can be beneficial when the time for the coverage is not sufficient to cover the entire target area. Experimental results show that the DmaxCoverage algorithm outperforms previous algorithms for these situations.