• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.859-866
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• 2019

Cybersecurity attack targeting a specific user is rising in number, even enterprises are trying to strengthen their cybersecurity. Network segmentation environment where public network and private network are separated could block information coming from the outside, however, it is unable to control outside information for business efficiency and productivity. Even if enterprises try to enhance security policies and introduce the network segmentation system and a solution incorporating CDR technology to remove unnecessary data contained in files, it is still exposed to security threats. Therefore, we suggest a system that uses file format conversion to transmit a secure file in the network separation environment. The secure file is converted into an image file from a document, as it reflects attack patterns of inserting malicious code into the document file. Additionally, this paper proposes a system in the environment which functions that a document file can keep information for incident response, considering forensic readiness.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.04a
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• pp.389-391
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• 2010

The Free surface influenced the wake behind a circular cylinder and its effects were investigated experimentally in a circulating water channe with the variation of water depth Instantaneous velocity fields were measured in this paper. the measured results has been compared with each other to investigate the flow characteristics of the circular cylinder's 2-dimensional section at $Re=1.0\times10^3$ using 2-frame grey level cross correlation PIV method. The flow around the circular cylinder with free surface affected the wake structure. especially, in case of d=1.0D, the boundary layer was measured in the whole area. The separation point and boundary layer of the circular cylinder could be controlled by the water depth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4152-4158
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• 2012

The Stereo X-ray inspection system is designed for effectively providing the additional information of objects than the conventional inspection system that offers only 2D cross-section of objects. We studied the geometric improvement of the stereo X-ray inspection system, the stereo matching algorithm of the single object using the edge and the volume reconstruction method for the inspected object. In this paper, we conduct a matching algorithm to find the correspondences between the images and reconstruct 3-D shapes of real objects using the stereo X-ray images. Also, we apply a new 3D reconstruction algorithm for the discrimination of two objects. For the separation of the overlapping objects, we calculate the vector of the object and divide inner and outer voxel of objects. And for the elimination of the overlapping area, we study the reconstruct 3D shapes using the threshold based Z-axis. The experimental results show that the proposed technique can enhance the accuracy of stereo matching and give more efficient visualization for overlap objects in the restricted environment.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.1
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• pp.73-81
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• 1999

This paper describes the methods which segment more efficiently the car license plate and the character region by using 1-D DCT. In the car images, a license plate region and a character region of the license plate can be distingushed by the regular high frequency components from the car images. In this method, it is shown that the regular high frequency componets are extracted by using DCT and license plate region is segmented in the car image and the caracter region is then seperated at the extracted license plate by using the previously extracted regular high frequency components. Some experiment results of the various images are shown. It has been shown from the results that the car license plates and the character regions can be segmented more exactly and efficiently than conventional methods.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.45-47
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• 2006

Cleft palate is a congenital deformity condition with separation of the two sides of the lip resulting in nose deformity. Evaluation of surgical corrections and outcome assessments for nose deformity due to the cleft lip depends mainly on doctor's subjective judgment. An objective method for evaluation of the condition and surgical outcome of nose deformity due to the cleft palate is needed. This study aimed at objective assessment of a cleft palate nose deformity condition by analyzing the following parameters obtained from photographic images of a cleft palate patients: (1) angle difference between two nostril axes. (2) center of the nostril and distance between two centers. (3) overlapped area of two nostrils, and (4) the overlapped area ratio of the two nostrils. A regression equation of doctor's grades was obtained using the eight parameters. Three plastic surgeons gave us the grades for the each photographic image by 10 increments with maximum grade of 100. The average reproducibility of the grades given by the three plastic surgeons and the three laymen using the developed program was $10.8{\pm}4.6%$ and $7.4{\pm}1.8%$, respectively. Kappa values representing the degree of consensus of the plastic surgeons and the three laymen were 0.43 and 0.83. respectively. Correlation coefficient of the grades evaluated by the surgeons and obtained by the neural network was 0.798. In conclusion. the developed neural network model provided us better reproducibility and much better consensus than doctor's subjective evaluation in addition to objectiveness and easy application.

• Journal of Navigation and Port Research
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• v.34 no.5
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• pp.331-336
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• 2010

The free surface influenced the wake behind a circular cylinder and its effects were investigated experimentally in a circulating water channel with the variation of water depth. Instantaneous velocity fields were measured in this paper. The measured results has been compared with each other to investigate the flow characteristics of the circular cylinder's 2-dimensional section at $Re=1.0{\times}10^3$ using 2-frame grey level cross correlation PIV method. The flow around the circular cylinder with free surface affected the wake structure. Especially, in case of d=1.0D, the boundary layer was measured in the whole area. The separation point and boundary layer of the circular cylinder could be controlled by the water depth.

• Journal of Navigation and Port Research
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• v.35 no.10
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• pp.805-810
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• 2011

An experiment was carried out to figure out the instantaneous flow characteristics in the wake of the transom stern's 2-dimensional section by 2-frame grey level cross correlation PIV method at $Re=3.5{\times}103$, $Re=7.0{\times}103$. The stern angles of models were learning at $45^{\circ}$(Model "A"), $90^{\circ}$(Model "B") and $135^{\circ}$(Model "C") respectively based on the survey results of real ships. The depth of wetted surface is 40mm from free surface. As Reynolds number increases, vortices increase in volume and move their way to the downstream. Flow separation appeared at the end of model's bottom.

• Journal of Navigation and Port Research
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• v.32 no.10
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• pp.771-776
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• 2008

The main purpose in having a control surface on a ship is to control the motion of it. It is the important element to determine the maneuvering characteristics of the ship. In this paper, the measured results has been compared with each other to predict the performance characteristics of flapped rudder's 2-dimensional section at $Re=3.0{\times}10^4$ using 2-frame grey level cross correlation PIV method. The side force of the rudder could be mainly improved by the lift force at 10 degrees angle of attack and the drag force at 20 degrees angle of attack. The separation point and boundary layer could be controlled by the change of the only flap's angle at 10 degrees angle of attack.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.6
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• pp.2086-2097
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• 2021

The current cultural assets are being restored depending on the opinions of experts (craftsmen). We intend to introduce digitalized artificial intelligence techniques, excluding the personal opinions of experts on reconstruction of such cultural properties. The first step toward restoring digitized cultural properties is separation. The restoration of cultural properties should be reorganized based on recorded documents, period historical backgrounds and regional characteristics. The cultural properties in the form of photographs or images should be collected by separating the background. In addition, when restoring cultural properties most of them depend a lot on the tendency of the restoring person workers. As a result, it often occurs when there is a problem in the accuracy and reliability of restoration of cultural properties. In this study, we propose a search method for learning stored digital cultural assets using AI technology. Pagoda was selected for restoration of Cultural Properties. Pagoda data collection was collected through the Internet and various historical records. The pagoda data was classified by period and region, and grouped into similar buildings. The collected data was learned by applying the well-known CNN algorithm for artificial intelligence learning. The pagoda search used Yolo Marker to mark the tower shape. The tower was used a total of about 100-10,000 pagoda data. In conclusion, it was confirmed that the probability of searching for a tower differs according to the number of pagoda pictures and the number of learning iterations. Finally, it was confirmed that the number of 500 towers and the epochs in training of 8000 times were good. If the test result exceeds 8,000 times, it becomes overfitting. All so, I found a phenomenon that the recognition rate drops when the enemy repeatedly learns more than 8,000 times. As a result of this study, it is believed that it will be helpful in data gathering to increase the accuracy of tower restoration.

• Geophysics and Geophysical Exploration
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• v.21 no.2
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• pp.112-124
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• 2018

Ocean-bottom seismic survey is a seismic acquisition technique which measures data by installing 4-component receiver on the sea floor. It can produce more improved data in quality than any other acquisition techniques. In the ocean-bottom seismic survey, however, the number of receivers is limited due to high cost. Since only a small number of receivers are used for acquisition, ocean-bottom seismic data may suffer from discontinuities of events over traces, which can result in spatial aliasing. In this paper, we implemented Kirchhoff migration using mirror-imaging algorithm to improve the quality of ocean-bottom seismic image. In order to implement the mirror imaging algorithm, the seismograms should be separated into up-going and down-going wavefields and the down-going wavefield should be used for migration. In this paper, we use the P-Z summation method to separate the wavefield. Numerical examples show that the migration results using mirror imaging algorithm have wider illumination than the conventional migration, especially in the shallow layers.