• Journal of Digital Convergence
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• v.13 no.11
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• pp.165-170
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• 2015

The Vocabulary Recognition System made by recognizing the standard vocabulary is seen as a decline of recognition when out of the standard or similar words. The vector values of the existing system to the model created by configuring the database was used in the recognition vocabulary. The model to be formed during the search for the recognition vocabulary is recognizable because there is a disadvantage not configured with a database. In this paper, it induced to recognize the vector model is formed by the search and configuration using a Bayesian model recognizes the Bhattacharyya distance measurement based on the vector model, by applying the Wiener filter improves the recognition rate. The result of Convergence of two method's are improved reliability experiments for distance measurement. Using a proposed measurement are compared to the conventional method exhibited a performance of 98.2%.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.279-285
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• 2015

In this paper, we present the design and implementation of a realtime DNS Query Analysis System to detect and to protect from DNS attacks. The proposed system uses mirroring to collect data in DMZ, then analizes the collected data. As a result of the analysis, if the proposed system finds attack information, the information is used as a filtering information of firewall. statistic of the collected data is viewed as a realtime monitoring information on the web. To verify the effictiveness of the proposed system, we have built the proposed system and conducted some experiments. As the result, Our proposed system can be used effectively to defend DNS spoofing, DNS flooding attack, DNS amplification attack, can prevent interior network's attackers from attacking and provides realtime DNS query statistic information and geographic information for monitoring DNS query using GeoIP API and Google API. It can be useful information for ICT convergence and the future work.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1837-1845
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• 2015

The longitudinal velocity is necessary for accurate vehicular positioning in urban environment. The pitch angle, which is a road slope, should be calculated to acquire the longitudinal velocity. However, it is impossible to consider very accurate pitch, when using a sensor and an algorithm. That's why process noise and positioning stimation error of IMU should be adjusted to the driving environment and fuse GPS, OBD data with ACF which consist of AKF, CF in this paper. Then, final pitch angle which is appropriate for driving environment is estimated by IMMKF in order to optimize the system model according to road slope models.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.29-36
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• 2016

Accuracy of GPS (global positioning system) deteriorates dramatically or positioning is impossible in urban area occasionally since high-rise buildings and elevated roads make the reception of navigation signal very difficult so that number of visible satellites decreases. In these cases, vertical error usually becomes much larger than the horizontal error due to the intrinsic geometry of GPS satellites. To obtain more accurate and reliable height information, this paper proposes a hybrid method that combines GPS and a low-cost barometric altimeter. In the proposed method, the sea-level pressure and the sea-surface temperature are applied to the output of the altimeter. Next, the difference between the ellipsoid and the geoid is compensated. Finally, a simple Kalman filter combines the compensated barometric altitude and the GPS height. By static and car experiments, performance of the proposed method is evaluated. By the experiment results, it can be seen that the proposed method improves the altitude accuracy considerably.

• Convergence Security Journal
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• v.19 no.4
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• pp.133-142
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• 2019

Although torrents and P2P sites or web hard are frequently used by users simply because they can be easily downloaded freely or at low prices, domestic torrent and P2P sites or web hard are very sensitive to copyright. Techniques have been researched and applied. Among these, title and string comparison method filtering techniques that block the number of cases such as file titles or combinations of key words are blocked by changing the title and spacing. Bypass is easy through. In order to detect and block illegal works for copyright protection, a technique for normalizing modified file titles is essential. In this paper, we compared the detection rate by searching before and after normalizing the modified file title of illegal works and normalizing the file title. Before the normalization, the detection rate was 77.72%, which was unfortunate while the detection rate was 90.23% after the normalization. In the future, it is expected that better handling of nonsense terms, such as common date and quality display, will yield better results.

• Journal of the Korea Convergence Society
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• v.11 no.2
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• pp.271-279
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• 2020

Squats and lunges are important exercises for strengthening the trunk and lower body among various free weight exercises. It should be achieved safe and effective excise through establishing of theoretical basis for exercise posture and standard movement. Therefore, it's necessary to develop the exercise model in order to prepare the scientific countermeasures for the prevent injuries and error movement through optimal exercise movement. For this purpose, it is effective to use appropriate instruments for motion compensation according to the optical motion and error motion. In this paper, we develop a motion model analysis system based on dynamic motion through the four-point load cell for dynamic motion analysis. Proposed analytical method, the optimal and the error motion numerical data is obtained through the dynamic motion analysis. And we verified that dynamic movement is simplified to establish the motion modeling according to the classification motion and the numerical quantification data for analyzing.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.195-201
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• 2020

This paper implemented quadcopter-type drone system and proposed the heuristic method for obtaining the optimum gain coefficients in order to minimize the settling time. Control system for quadcopter posture stabilization reads the posture data from accelerator and gyro sensor, revises the original posture data using Mahony filter, and drives 4 DC motors using PID controller. The first step of the proposed method is to obtain the gain coefficients using the Ziegler-Nichols method, and then determine the optimum gain coefficients using the heuristic method at the next 3 steps. The experimental result shows that the maximum overshoot decreases from 44.3 to 29.8 degrees and the settling time decreases from 2.6 to 1.7 seconds compared to the Ziegler-Nichols method. Therefore, we proved that the proposed method works well in quadcopter flight system with high motor noise while reducing trial and error to obtain the optimal PID gain coefficients.

• Convergence Security Journal
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• v.16 no.7
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• pp.167-172
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• 2016

The purpose of this study is to provide implications for preventing insider information leakages in public agencies for national security. First, the study examined the definitions and current usage of information security systems of public agencies were examined. Second, web-service base information leaks and malware-base information leaks were discussed and three major credit card companies' personal information leakage cases were analyzed. Based on the analysis, four solutions were provided. First, information leakages can be protected by using web filtering solutions based on the user, which make possible to limit frequencies of malware exposures. Second, vaccine programs and vaccine management system should be implemented to prevent information leakages by malware. Third, limit the use of portable devices within local networks to prevent information leakages and vaccines programs for malware should be regularly used. Forth, to prevent information leakages by smartphone malwares, data encryption application should be used to encrypt important information.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.1-7
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• 2018

Feature selection, one of data preprocessing techniques, is one of major research areas in many applications dealing with large dataset. It has been used in pattern recognition, machine learning and data mining, and is now widely applied in a variety of fields such as text classification, image retrieval, intrusion detection and genome analysis. The proposed method is based on a genetic algorithm which is one of meta-heuristic algorithms. There are two methods of finding feature subsets: a filter method and a wrapper method. In this study, we use a wrapper method, which evaluates feature subsets using a real classifier, to find an optimal feature subset. The training dataset used in the experiment has a severe class imbalance and it is difficult to improve classification performance for rare classes. After preprocessing the training dataset with SMOTE, we select features and evaluate them with various machine learning algorithms.

• Journal of IKEEE
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• v.17 no.4
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• pp.440-445
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• 2013

This paper proposes a local estimation system which combines Cell Divide Algorithm with low-cost GPS/INS fused by Extended Kalman Filter(EKF) for localization of Quad-rotor when it returns to the departure point. In the research, the low-cost GPS and INS are fused by EKF to reduce the local error of low-cost GPS and the accumulative error of INS due to continuous integration of sensor error values. When the Quad-rotor returns to the departure point in the fastest path, a moving path can be known because it moves straight, where Cell Divide Algorithm is used to divide moving route into the cells. Then it determines the closest position of data of GPS/INS system fused by EKF to obtain the improved local data. The proposed system was verified through comparing experimental localization results obtained by using GPS, GPS/INS and GPS/INS with Cell Divide Algorithm respectively.