• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.907-914
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• 2009

An approach to 3D visualization of multiple sound sources has been developed with the application of a moving array technique. Frequency domain beamforming algorithm is used to generate a beam power map and the sound source is modeled as a point source. When a conventional delay and sum beamformer is used, it is considered that 2D distribution of sensors leads to have deficiency in spatial resolution along a measurement distance. The goal of moving an array in this study is to form 3D array aperture surrounding multiple sound sources so that the improved spatial resolution in a virtual space can be expected. Numerical simulation was made to examine source localization capabilities of various shapes of array. The 3D beam power maps of hemispherical and spherical distribution are found to have very sharp resolution. For experiments, several sound sources were placed in the middle of defined virtual space and arc-shaped line array was rotated around the sources. It is observed that spherical array shows the most accurate determination of multiple sources' positions.

• ETRI Journal
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• v.29 no.5
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• pp.559-568
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• 2007

This paper presents a new distortion control scheme with a simple estimation model for the propagation errors incurred by dropping some parts of the bitstream in a frame dropping-coefficient dropping (FD-CD) transcoder. The primary goal of this paper is to facilitate bit-rate conversions and rate-distortion controls in the compressed domain without introducing a full decoding and reencoding system in the pixel domain. First, the error propagation behavior over several frame sequences due to coefficient dropping is investigated on the basis of statistical and empirical properties. Then, such properties are used to develop a simple estimation model for the CD distortion accounting for the characteristics of the underlying coded-frame. Finally, the proposed estimation model allows us to determine the amount of coefficient dropping and to effectively allocate rate-distortions into coded-frames. Experimental results show that the proposed estimation model accurately describes the characteristics of propagation errors adaptively in the compressed domain and can be easily applied to distortion control over different kinds of video sequences.

• Proceedings of the KAIS Fall Conference
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• 2003.11a
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• pp.57-64
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• 2003

Achieving the beneficiary goal of recent discovery in human genome project still needs a way to retrieve and analyze the exponentially expanding bio-related information. Research on bio-related fields naturally applies knowledge discovered to the current problem and make inferences to extract new information where shared concepts and data containing information need to be defined and used in a coherent way. In such a professional domain, while the need to help users reduce their work and to improve search results has been emerged. methods for systematic retrieval and adequate exchange of relevant information are still in their infancy. The design of our system aims at improving the quality of information retrieval in a professional domain by utilizing both corpus-based and concept-based ontology. Meta-rules of helping users to make an adequate query are formed into an ontology in the domain. The integration of those knowledge permits the system to retrieve relevant information in a more semantic and systematic fashion. This work mainly describes the query models with details of GUI and a secondary query generation of the system.

• Journal of the Korea Society for Simulation
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• v.3 no.2
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• pp.1-13
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• 1994

Deep reasoning procedures are model-based, inferring single or multiple causes and/or timing relations from the knowledge of behavior of component models and their causal structure. The overall goal of this paper is to develop an automated deep reasoning methodology that exploits deep knowledge of structure and behavior of a system. We have proceeded by building a software environment that uses such knowledge to reason from advanced symbolic simulation techniques introduced by Chi and Zeigler. Such reasoning system has been implemented and tested on several examples in the domain of performance evaluation, and event-based control.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.278-282
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• 2002

In this paper, a dual-band CPW antenna is designed with the aid of Genetic Algorithm and Finite-Difference Time-Domain method. The design goal is to minimize the magnitude of S$\sub$11/ in the frequency band between 1.8㎓ and 2.4㎓. The resonance frequencies are shifted by about 80MHz and 50MHz from the desired frequencies at 1.8㎓ and 2.4㎓ respectively. But the bandwidth agrees well with that of Simulation.

• Proceedings of the Korean Society for Language and Information Conference
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• 1996.02a
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• pp.137-146
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• 1996

Our research goal has been the development of a domain independent natural language processing (NLP) system suitable for information retrieval. As part of that research, we have investigated ways to automatically extend the semantics of a lexicon derived from machine-readable lexical sources. This paper details the extraction of thematic roles derived from lexical patterns in a machine-readable dictionary.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.351-354
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• 2002

NAPTR(Naming Authority Pointer) is a type of resource record specified IETF RFC 2915. NAPTR enables to register various services in tile domain name systems and thus Provides a way to discover services available on specific hosts. This paper describes the design and implementation of a proxy DNS system aimed at supporting NAPTRS. The goal of this work is to study on the feasibility of the service discovery registered in DNS via NAPTR records. This research result can be applied to service discovery in the resource information management for high performance GRID environments as well as to implement generic ENUM services

• The Journal of Korean Association of Computer Education
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• v.7 no.5
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• pp.9-21
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• 2004

In spite of the strong request that Internet, a new IT technique, should be extensively used in classroom settings, WBI is not still wide spread. One possible reason is that most WBIs developed so far are not qualitatively different from the traditional classroom ones and various design models for WBI are unknown. Developing a WBI program according to Goal-based Scenarios (GBS), a constructivistic instructional design model, this study offers a useful case for the design and development of WBI to educators and implementers. The program developed embodied seven important components of the GBS model. The development process also included needs assessment, task analysis, and learner and environment analysis, which are the basic components of the domain of instructional design. The GBS development case in this article will provide concrete guidelines to educational practitioners who have an intention to create a new type of WBI in schools as well as in corporate.

• Journal of Digital Contents Society
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• v.11 no.3
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• pp.331-339
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• 2010

On intranet system, it is essential element for providing information to decrease response time. To realize this efficiencies of response time of the network, a lot of research have been conducted. The purpose of the research and implementation is to shorten the response time of information system. We can realize final goal of information system through fast response time. This final goal of information system is to secure the performance efficiency within the required time. In order to acquire the method of warranty of fast response time, the efficient measurement method is essential. This research suggests a latency test techniques being used on infrastructure system and also offers a response time measurement methodology. Methodology proposed in this research has proven that it is possible to measure response time through the scheduled method. Also it is possible to develop a enhanced networking capabilities, and information system capabilities for the development of information system.

• Wind and Structures
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• v.11 no.2
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• pp.75-96
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• 2008

A better understanding of tornado-induced wind loads is needed to improve the design of typical structures to resist these winds. An accurate understanding of the loads requires knowledge of near-ground tornado winds, but observations in this region are lacking. The first goal of this study was to verify how well a CFD model, when driven by far field radar observations and laboratory measurements, could capture the flow characteristics of both full scale and laboratory-simulated tornadoes. A second goal was to use the model to examine the sensitivity of the simulations to various parameters that might affect the laboratory simulator tornado. An understanding of near-ground winds in tornadoes will require coordinated efforts in both computational and physical simulation. The sensitivity of computational simulations of a tornado to geometric parameters and surface roughness within a domain based on the Iowa State University laboratory tornado simulator was investigated. In this study, CFD simulations of the flow field in a model domain that represents a laboratory tornado simulator were conducted using Doppler radar and laboratory velocity measurements as boundary conditions. The tornado was found to be sensitive to a variety of geometric parameters used in the numerical model. Increased surface roughness was found to reduce the tangential speed in the vortex near the ground and enlarge the core radius of the vortex. The core radius was a function of the swirl ratio while the peak tangential flow was a function of the magnitude of the total inflow velocity. The CFD simulations showed that it is possible to numerically simulate the surface winds of a tornado and control certain parameters of the laboratory simulator to influence the tornado characteristics of interest to engineers and match those of the field.