• Journal of Korea Spatial Information System Society
• /
• v.5 no.1 s.9
• /
• pp.65-74
• /
• 2003

Location-based service is an important spatiotemporal database application area that provides the location-aware information of wireless terminals via positioning devices such as GPS. With the rapid advances of wireless communication systems, the requirement of mobile application areas including traffic, mobile commerce and supply chaining management became the center of attention for various research issues in spatiotemporal databases. In this paper we present the A-Quadtree, an efficient indexing method for answering location-based queries where the movement vector information (e.g., speed and velocity) is not presented. We implement the A-Quadtree with an index structure for object identifiers as a.Net component to apply the component to multiplatforms. We present our approach and describe the performance evaluation through various experiments. In our experiments, we compare the performance with previous approaches and show the enhanced efficiency of our method.

• Journal of Biomedical Engineering Research
• /
• v.16 no.1
• /
• pp.95-100
• /
• 1995

In this study, we have evaluated the effect of amplitude and frequency perturbation of EGG signal for single vowels associated with laryngeal pathology. The normal EGG signal was properly characterized by an autoregressive model which has an optimal order of ninth using the parametric method. This can be analyzed by determining the transfer function. Perturbations in the fundamental pitch and in the peak amplitude of EGG signal measured with a four-electrode system using the modulation/demodulation techniques were investigated for the purpose of developing a decision criteria for the laryngeal function analysis. The abnormal EGG signal has nonperiodic and unstable characteristics. It can be discriminated by the calculation of opening and closing time of glottis using the EGG signal. In case of normal and abnormal subjects, m$\pm$0.5*sd was discriminating line for frequency perturbation and m$\pm$2*sd for normal amplitude perturbations, respectively. Also, The normal and abnormal cases of the subjects can be discriminated effectively using the pattern of attractor derived with Hilbert transform of EGG signal.

• Journal of KIISE:Computer Systems and Theory
• /
• v.34 no.7
• /
• pp.296-303
• /
• 2007

Color quantization replaces the color of each pixel with the closest representative color, and thus it makes the resulting image partitioned into uniformly-colored regions. As a consequence, continuous, detailed variations of color over the corresponding regions in the original image are lost through color quantization. In this paper. we present a novel blind scheme for restoring such variations from a color-quantized input image without it priori knowledge of the quantization method. Our scheme identifies which pairs of uniformly-colored regions in the input image should have continuous variations of color in the resulting image. Then, such regions are seamlessly stitched through optimization while preserving the closest representative colors. The user can optionally indicate which regions should be separated or stitched by scribbling constraint brushes across the regions. We demonstrate the effectiveness of our approach through diverse examples, such as photographs, cartoons, and artistic illustrations.

• Journal of Korean Library and Information Science Society
• /
• v.51 no.2
• /
• pp.103-131
• /
• 2020

This study was started with the aim of grasping the current status of research data management of forestry engineering researchers. In order to achieve the research purpose, the survey was conducted using a tool called DAF (Data Asset Framework). DAF is an investigative tool that provides a means to identify, position, describe and evaluate how the agency manages research data. Using this DAF, the research data management status was analyzed for researchers in the field of forestry engineering at the National Institute of Forest Science. As a result of analysis, the current status and problems of the five categories such as the method and type of research data creation, sharing, storage, preservation, and reuse were identified, and solutions were presented in relation to the problems. This study is a basic investigation using a systematic tool such as DAF, and can be used as a reference for analyzing the current status and problems of research data when designing RDM system in a specific field.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.12
• /
• pp.2279-2284
• /
• 2017

Recent wireless communications using the unlicensed band have been on the rise and the range of use is increasing. The license-exempted band is a prerequisite for accepting interference between telecommunication equipment. In particular, the interference phenomenon of Bluetooth, wireless LAN, and RFID (Radio Frequency Identification) using the 2.4 GHz band is getting serious. In such urban areas, the wireless transmission medium may be in a bad state. There are roughly two ways to make effective transmission in this environment. The first is the IEEE 802.11 RTS / CTS method and the second is the frame fragmentation method. In this paper, it is difficult to transmit a frame over a certain size in a jamming environment due to the interference of the wireless environment. In this environment, we implement a frame division transmission scheme that guarantees effective transmission and reliability by dividing a frame into smaller units in order to perform reliability transmission and efficient transmission.

• Journal of KIISE:Software and Applications
• /
• v.36 no.4
• /
• pp.306-319
• /
• 2009

A name is a key feature for distinguishing people, but we often fail to discriminate people because an author may have multiple names or multiple authors may share the same name. Such name ambiguity problems affect the performance of document retrieval, web search and database integration. Especially, in bibliography information, a number of errors may be included since there are different authors with the same name or an author name may be misspelled or represented with an abbreviation. For solving these problems, it is necessary to disambiguate the names inputted into the database. In this paper, we propose a method to solve the name ambiguity by using social networks constructed based on the relations between authors. We evaluated the effectiveness of the proposed system based on DBLP data that offer computer science bibliographic information.

• The KIPS Transactions:PartA
• /
• v.10A no.1
• /
• pp.7-14
• /
• 2003

In order to cope with DoS (Denial of Service) attacks disturbing delivery of intended services by exhausting resources of computing nodes, we need a solution to recognize important resources for the essential services which have to be maintained under any circumstances and to adapt the system to the urgent situation and reconfigure itself properly. In this paper, we present a two-phase scheme to handle the problem. In the first phase, by means of dynamic resource reallocation within a computing node, we try to make the selected essential services survive even after the occurrence of an attack. For the second phase when it becomes impossible to continue the service in spite of the actions taken in the first phase, we apply server replication in order to continue the transparent provision of the essential services with the end users by utilizing redundant computing nodes previously arranged. Experimental result obtained on a testbed reveals the validity of the proposed scheme. A comparison with other proposed schemes has been conducted by analyzing the performance and the cost.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.30 no.2
• /
• pp.253-261
• /
• 2020

This study examines the technologies and application processes related to the use of pseudonym data of companies after the passage of the Data 3 Act to activate the data economy in earnest, and what companies should prepare to use pseudonym data and what will happen in the process It was intended to contribute to the elimination of uncertainty. In the future, companies will need to extend the information security management system from the perspective of the existing IT system to manage and control data privacy protection and management from a third party provisioning perspective. In addition, proper pseudonym data use control should be implemented even in the data use environment utilized by internal users. The economic effect of market change and heterogeneous data combination due to the use of pseudonymized data will be very large, and standards for appropriate non-identification measures and risk assessment criteria for data utilization and transaction activation should be prepared in a short time.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.7
• /
• pp.844-850
• /
• 2016

This study pertains to the extraction of the road noise component of signals from a vehicle's interior noise via the traditional frequency domain and time domain system identification methods. For road noise extraction based on the frequency domain system identification method, the appropriate matrix inversion strategy is investigated and causal and non-causal impulse response filters are compared. Furthermore, appropriate data lengths for the frequency domain system identification method are investigated. In addition to the traditional road noise extraction methods based on frequency domain system identification, a new approach to extract road noise via the time domain system identification method based on a parametric input-output model is proposed and investigated in the present study. In this approach, instead of constructing a higher order model for the full-band road noise, input and output signals are processed in the subband domain and lower order parametric models optimal to each subband are determined. These parametric models are used to extract road noises in each subband; the full band road noise is then reconstructed from the subband road noises. This study shows that both the methods in the frequency domain and the time domain successfully extract the road noise from the vehicle's interior noise.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.40 no.6
• /
• pp.98-105
• /
• 2003

We propose a new technique of deinterleaving multiple radar pulse sequences by means of genetic algorithm for threat identification in electronic warfare(EW) system. The conventional approaches based on histogram or continuous wavelet transform are so deterministic that they are subject to failing in detection of individual signal characteristics under real EW signal environment that suffers frequent signal missing, noise, and counter-EW signal. The proposed algorithm utilizes the probabilistic optimization procedure of genetic algorithm. This method, a time-of-arrival(TOA) only strategy, constructs an initial chromosome set using the difference of TOA. To evaluate the fitness of each gene, the defined pulse phase is considered. Since it is rare to meet with a single radar at a moment in EW field of combat, multiple solutions are to be derived in the final stage. Therefore it is designed to terminate genetic process at the prematured generation followed by a chromosome grouping. Experimental results for simulated and real radar signals show the improved performance in estimating both the number of radar and the pulse repetition interval.