• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.136-142
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• 2002

In this thesis. we present the cyber lecture system based on XML that uses the communication network as the 100Mbps LAN. The system was designed to analysis the existing cyber lecture system and its details arid to examine web system architecture and XML 3-tier model The result of the study consists of he cyber lecture system based on XML developed on 100Mbps LAN to improve method of the cyber lecture system by using ma 3-tier model arid utilisation of web interface to offer handiness of the cyber lecture system.

• Journal of the Korea Society of Computer and Information
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• v.13 no.3
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• pp.123-130
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• 2008

To avoid some protection systems such as firewall, P2P applications have recently used to apply dynamic port numbers. Reliable estimates of P2P traffic require examination of packet payload, a methodological land mine from legal, privacy technical, logistic, and fiscal perspectives. Indeed, access to user payload is often rendered impossible by one of these factors, inhibiting trustworthy estimation of P2P growth and dynamics. Despite various methods such as port-based and signature-based techniques, it still dose not satisfy the method which uses both qualitative and quantitative aspects. In this paper, a method using SVM mechanism which discriminate the P2P traffic from non-P2P traffics using differences between P2P and other application traffics is suggested. This is a systematic methodology to identify P2P networks, and without relying on packet payload.

• Journal of Korea Multimedia Society
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• v.19 no.8
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• pp.1636-1645
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• 2016

In navigation systems that use collected trajectory for routing, the number and diversity of trajectory data are crucial despite the infeasible limitation which is that all routes should be collected in person. This paper suggests an algorithm combining trajectories only by collected GPS data and generating new routes for solving this problem. Using distance between two trajectories, the algorithm estimates road intersection, in which it also predicts the correlated direction of them with geographical coordinates and makes a decision to combine them by the correlated direction. With combined and generated trajectory data, this combination way allows trajectory-based navigation to guide more and better routes. In our study, this solution has been introduced. However, the ways in which correlated direction is decided and post-process works have been revised to use the sequential pattern of triangles' area GPS information between two trajectories makes in road intersection and intersection among sets comprised of GPS points. This, as a result, reduces unnecessary combinations resulting redundant outputs and enhances the accuracy of estimating correlated direction than before.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.3-11
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• 2015

An advanced receiver which can manage inter-cell interference is required to cope with the explosively increasing mobile data traffic. 3rd Generation Partnership Project (3GPP) has discussed network assisted interference cancellation and suppression (NAICS) to improve signal-to-noise-plus-interference ratio (SINR) and receiver performance by suppression or cancellation of interference signal from inter-cells. In this paper, we propose the advanced receiver based on soft decision to reduce the interference from neighbor cell in LTE-Advanced downlink system. The proposed receiver can suppress and cancel the interference by calculating the unbiased estimation value of interference signal using minimum mean square error (MMSE) or interference rejection combing (IRC) receiver. The interference signal is updated using soft information expressed by log-likelihood ratio (LLR). We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced downlink system. Simulation results show that the proposed receiver can improve SINR, throughput, and spectral efficiency of conventional system.

• The Journal of Korean Association of Computer Education
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• v.17 no.2
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• pp.107-113
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• 2014

In this study, we design and implement an eye-gaze estimation system based on the extraction of eye contour and pupil region. In order to effectively extract the contour of the eye and region of pupil, the face candidate regions were extracted first. For the detection of face, YCbCr value range for normal Asian face color was defined by the pre-study of the Asian face images. The biggest skin color region was defined as a face candidate region and the eye regions were extracted by applying the contour and color feature analysis method to the upper 50% region of the face candidate region. The detected eye region was divided into three segments and the pupil pixels in each pupil segment were counted. The eye-gaze was determined into one of three directions, that is, left, center, and right, by the number of pupil pixels in three segments. In the experiments using 5,616 images of 20 test subjects, the eye-gaze was estimated with about 91 percent accuracy.

• The Journal of the Korean dental association
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• v.58 no.7
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• pp.388-397
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• 2020

Objective: The purpose of the study was to calculate the effective and absorbed organ doses of cone-beam computed tomography (CBCT) in pediatric patient using personal computer-based Monte Carlo (PCXMC) software and to compare them with those measured using thermoluminescent dosimeters (TLDs) and anthropomorphic phantom. Materials and Methods: Alphard VEGA CBCT scanner was used for this study. A large field of view (FOV) (20.0 cm × 17.9 cm) was selected because it is a commonly used FOV for orthodontic analyses in pediatric patients. Ionization chamber of dose-area product (DAP) meter was located at the tube side of CBCT scanner. With the clinical exposure settings for a 10-year-old patient, DAP value was measured at the scout and main projection of CBCT. Effective and absorbed organ doses of CBCT at scout and main projection were calculated using PCXMC and PCXMCRotation software respectively. Effective dose and absorbed organ doses were compared with those obtained by TLDs and a 10-year-old child anthropomorphic phantom at the same exposure settings. Results: The effective dose of CBCT calculated by PCXMC software was 292.6 μSv, and that measured using TLD and anthropomorphic phantom was 292.5 μSv. The absorbed doses at the organs largely contributing to effective dose showed the small differences between two methods within the range from -18% to 20%. Conclusion: PCXMC software might be used as an alternative to the TLD measurement method for the effective and absorbed organ dose estimation in CBCT of large FOV in pediatric patients.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.6
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• pp.36-42
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• 2009

In the mobile device environment, the context-aware computing has been emerging as a core technology of ubiquitous computing. Compared with a desktop computer, a user interface and resource of mobile device is very limited. Traditional desktop-based user interface has been developed on the basis that a user's activity is static state. In contrast, mobile devices are not able to utilize representative desktop-based interaction mechanisms such as a keyboard and mouse, not only because the activity of a user is dynamic state, but mobile devices have limited resources and small LCD display. In this paper, we introduce an intelligent control system for the mobile device that can utility effectively the limited resource and complement the poor user interface by using an accelerometer being able to sense the physical activity and posture. The proposed system can estimate the user activity, static and dynamic states, and posture watching the PDA at the same time, and the proposed intelligent control system as its application, the backlight ON/OFF on the PDA, is run by the result of the user's behavior.

• Imaging Science in Dentistry
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• v.48 no.1
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• pp.21-30
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• 2018

Purpose: To calculate the effective doses of cone-beam computed tomography (CBCT) using personal computer-based Monte Carlo (PCXMC) software (Radiation and Nuclear Safety Authority, Helsinki, Finland) and to compare the calculated effective doses with those measured using thermoluminescent dosimeters (TLDs) and an anthropomorphic phantom. Materials and Methods: An Alphard VEGA CBCT scanner (Asahi Roentgen Ind. Co., Kyoto, Japan) with multiple fields of view (FOVs) was used for this study. The effective doses of the scout and main projections of CBCT using 1 large and 2 medium FOVs with a height >10 cm were calculated using PCXMC and PCXMCRotation software and then were compared with the doses obtained using TLD-100 LiF and an anthropomorphic adult human male phantom. Furthermore, it was described how to determine the reference points on the Y- and Z-axes in PCXMC, the important dose-determining factors in this software. Results: The effective doses at CBCT for 1 large ($20.0cm{\times}17.9cm$) and 2 medium FOVs ($15.4cm{\times}15.4cm$ and $10.2cm{\times}10.2cm$) calculated by the PCXMC software were 181, 300, and $158{\mu}Sv$, respectively. These values were comparable (16%-18% smaller) to those obtained through TLD measurements in each mode. Conclusion: The use of PCXMC software could be an alternative to the TLD measurement method for effective dose estimation in CBCT with large and medium FOVs.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.5
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• pp.492-502
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• 2021

In electronic warfare, source enumeration and direction-of-arrival estimation are important. The source enumeration method based on eigenvalues of covariance matrix from received is one of the most used methods. However, there are some drawbacks such as accuracy less than 100 % at high SNR, poor performance at low SNR and reduction of maximum number of estimating sources. We suggested new method based on eigenvalues gaps, which is named AREG(Accumulated Ratio of Eigenvalues Gaps). Meanwhile, FGML(Fast Gridless Maximum Likelihood) which reconstructs the covariance matrix was suggested by Wu et al., and it improves performance of the existing source enumeration methods without modification of algorithms. In this paper, first, we combine AREG with FGML to improve the performance. Second, we compare the performance of source enumeration and direction-of-arrival estimation methods in Rayleigh fading. Third, we suggest new method named REG(Ratio of Eigenvalues Gaps) to reduce performance degradation in Rayleigh Fading environment of AREG.

• Journal of the Korea Society of Computer and Information
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• v.19 no.10
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• pp.1-12
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• 2014

This paper implements and improves the performance of high computational subtractive clustering algorithm using a single instruction, multiple data (SIMD) based many-core processor. In addition, this paper implements five different processing element (PE) architectures (PEs=16, 64, 256, 1,024, 4,096) to select an optimal PE architecture for the subtractive clustering algorithm by estimating execution time and energy efficiency. Experimental results using two different medical images and three different resolutions ($128{\times}128$, $256{\times}256$, $512{\times}512$) show that PEs=4,096 achieves the highest performance and energy efficiency for all the cases.