• Progress in Medical Physics
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• v.27 no.1
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• pp.8-13
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• 2016

Dual energy cone-beam CT can distinguish two materials with different atomic compositions. The principle of dual energy cone-beam CT based on modulation layer is that higher energy spectrum can be acquired at blocked x-ray window. To evaluate the possibility of modulation layer based dual energy cone-beam CT, we analyzed x-ray spectrum for various thicknesses of modulation layers by Monte Carlo simulation. To compare with the results of simulation, the experiment was performed on prototype cone-beam CT for 50~100 kVp with CdTe XR-100T detector. As the result of comparing, the mean energy of energy spectrum for 80 kVp are well matched with that of simulation. The mean energy of energy spectrum for 80 and 120 kVp were increased as 1.67 and 1.52 times by 2.0 mm modulation layer, respectively. We realized that the virtual dual energy x-ray source can be generated by modulation layer.

• Journal of radiological science and technology
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• v.30 no.2
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• pp.113-119
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• 2007

It is important to consider the contrast of object in Mammography because an absorption gap between tissues of body and breast in breast is low. This study is to evaluate MTF image with resolution chart according to change of combination of target and filter. The results were as follows : 1. There were significant differences in X-ray energy according to combination of filter(Mo/Mo, Mo/Rh. Mo/Al, Rh/Rh, Rh/Al) and acrylic thickness(2 cm, 3 cm, 4 cm). 2. The value of lp/mm on MTF to 0.5 showed that the sharpness in MTF curve was 2.4 compared to Mo/Mo and 2cm acryl, 2.63 in Mo/Rh and 4 cm acryl, and 2.9 in Rh/Rh and 6cm acryl. 3. The value of lp/mm on MTF showed that the resolution in MTF curve was 6.0 compared to Mo/Mo and 2 cm acryl, 4.60 in Rh/Al and 4cm acryl, and 6.03 in Rh/Al and 6 cm acryl. 4. The value of MTF on 2.5 lp/mm distinguishable visually was 0.48 compared to Mo/Mo and 2 cm acryl, 0.53 in Mo/Rh and 4cm acryl, and 0.59 in Rh/Rh and 6cm acryl. 5. For the evaluation of an image of the mammo-phantom, the score of Mo/Mo was 12 points, Mo/Rh 11, Rh/Rh 10.5, Mo/Al 10, Rh/Al 9.0, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.55-63
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• 2007

The Group Digital Surveillance System for Fishery Safety and Security (GDSS-F2S) is to provide the target tracking information and the target identification information in order to secure an huge aquaculture farm-field from a thief. The two information, however, is not enough to indict the thief due to the lack of lawful evidences for the crime actions. To overcome this problem, we consider the target image information as one of solutions after discussion with the effective countermeasure tools for the crime actions with scenario-based analysis according to the geological feature of aquaculture farm-field. To capture the real-time image for the trespassing targets in the aquaculture farm-field area, we developed the image capture system which is consists of ultra sensitive CCD(Charge-Coupled Device) camera with 0.0001 Lux and supplementary devices. As results from the field tests for GDSS-F2S with image capture system, the high definite images of the vehicle number plate and shape, person's actions and features are obtainable not only day time but also very dark night without moon light. Thus it is cleary known that the improved GDSS-F2S with image capture system can provide much enough lawful evidences for the crime actions of targets.

• Journal of KIISE
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• v.44 no.8
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• pp.803-812
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• 2017

T-commerce is technology-fusion service on which the user can purchase using data broadcasting technology based on bi-directional digital TVs. To achieve the best revenue under a limited environment in regard to the channel number and the variety of sales goods, organizing broadcast programs to maximize the expected sales considering the selling power of each product at each time slot. For this, this paper proposes a method to predict the sales of goods when it is assigned to each time slot. The proposed method predicts the sales of product at a time slot given the week-in-year and weather of the target day. Additionally, it combines a statistical predict model applying SVD (Singular Value Decomposition) to mitigate the sparsity problem caused by the bias in sales record. In experiments on the sales data of W-shopping, a T-commerce company, the proposed method showed NMAE (Normalized Mean Absolute Error) of 0.12 between the prediction and the actual sales, which confirms the effectiveness of the proposed method. The proposed method is practically applied to the T-commerce system of W-shopping and used for broadcasting organization.

• The KIPS Transactions:PartD
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• v.14D no.6
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• pp.585-596
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• 2007

XML data generally consists of a hierarchical tree-structure which is reflected in mechanisms to store and retrieve XML data. Therefore, when storing XML data in the database, the hierarchical relationships among the XML elements are taken into consideration during the restructuring and storing of the XML data. Also, in order to support the search queries from the user, a mechanism is needed to compute the hierarchical relationship between the element structures specified by the query. The structural join operation is one solution to this problem, and is an efficient computation method for hierarchical relationships in an in database based on the node numbering scheme. However, in order to process a tree structured XML query which contains a complex nested hierarchical relationship it still needs to carry out multiple structural joins and results in another problem of having a high query execution cost. Therefore, in this paper we provide a preprocessing mechanism for effectively reducing the cost of multiple nested structural joins by applying the concept of equivalence classes and suggest a query path reduction algorithm to shorten the path query which consists of a regular expression. The mechanism is especially devised to reduce path queries containing branch nodes. The experimental results show that the proposed algorithm can reduce the time requited for processing the path queries to 1/3 of the original execution time.

• Weed & Turfgrass Science
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• v.6 no.4
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• pp.306-312
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• 2017

This study was carried out to develop new hybrid zoysiagrass cultivar 'Seah' (The application no. for cultivar protection : 2014-22). Native zoysiagrasses were collected from south-west seaside of Korea from 2010 to 2011. Artificial crossing was conducted to develop F1 hybrid between Z2011 (Z. sinica) and NM1 (Z. matrella) at plastic house in 2011. Among the progenies, 'Seah' showed fine leaf texture and high shoot density from the space planting plots at field. 'Seah' showed genetically light green color, with fine leaf with 1.8mm and height to the lowest leaf blade was 1.94 cm. Ground coverage rate was slower than medium leaf zoysiagrass (Jung-gi), but plant height of 7.1 cm was the lowest among the compared zoysiagrasses and height to lowest leaf of 1.94 cm was lower than most zoysiagrass, which may allow low mowing height.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.1
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• pp.7-14
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• 2010

In this paper, we introduce a hierarchical internet application traffic classification system based on SVM as an alternative overcoming the uppermost limit of the conventional methodology which is using the port number or payload information. After selecting an optimal attribute subset of the bidirectional traffic flow data collected from the campus, the proposed system classifies the internet application traffic hierarchically. The system is composed of three layers: the first layer quickly determines P2P traffic and non-P2P traffic using a SVM, the second layer classifies P2P traffics into file-sharing, messenger, and TV, based on three SVDDs. The third layer makes specific classification of the entire 16 application traffics. By classifying the internet application traffic finely or coarsely, the proposed system can guarantee an efficient system resource management, a stable network environment, a seamless bandwidth, and an appropriate QoS. Also, even a new application traffic is added, it is possible to have a system incremental updating and scalability by training only a new SVDD without retraining the whole system. We validate the performance of our approach with computer experiments.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.68-76
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• 2018

In this paper, we describe the correlation processing method of multi-polarization observation data of the Daejeon Correlator. VLBI observations include single or multiple polarized observations depending on the type of object. Polarization observations are performed to observe the characteristics of the object. During the observations of the celestial object, polarization measurements are also performed to determine the delay values and causes of changes in the object. Correlation processing of polarization observation data of the Daejeon correlator is proposed by OCTAVIA of a synchronous reproduction processing apparatus that outputs data input to each antenna unit by using an output bit selection function to convert bits and the order of the data streams is changed, And the input of the Daejeon correlator is configured to perform the polarization correlation processing by conducting correlation processing by setting the existing stream number to be the same. Correlation processing is conducted on the test data observed for the polarization correlation processing and it is verified through experiments that the polarization correlation processing method of the proposed Daejeon correlator is effective.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.3
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• pp.245-251
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• 2004

Recently, in a field of cadastre, a computerization of cadastral map is in progress with great growth of GSIS field. Also, the needs fer the integration of land and building information are widely increasing for integral-management and its application of various land related information. Through a revision of cadastral laws to replace the existing 2D-Cadastre with the 3D-Cadastre, a legal basis to register the position of buildings and facilities is prepared in the governmental or civil fields. This paper presented 3D-Cadastre theory that has been studied on Europe and surveyed building position directly with Totalstation at cadastral control point after choosing pilot test area, Also, the most efficient surveying method of registering building in a cadastral map is presented with comparing and analyzing building position after surveying digital orthophoto and digital map. And it is constructed a 3D information cadastral map model that can make the integral management of land, building, connecting land recorders, building management ledgers, building titles, building pictures, and related attribute information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.497-505
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• 2015

Existing Wi-Fi networks require users to follow network settings of the AP (Access Point), resulting in inconveniences for users, and the password of the AP is shared by all users connected to the AP, causing security information leaks as time goes by. We propose, in this work, a personalized secure Wi-Fi network, in which each user is assigned her own virtual Wi-Fi network. One virtual Wi-Fi per user makes the user-centric network configuration possible. A user sets a pair of her own SSID and password on her device a priori, and the AP publishes its public key in a suitable way. The AP also maintains an open Wi-Fi channel, to which users can connect anytime. On user's request, the user device sends a connection request message containing a pair of SSID and password encrypted with the AP's public key. Receiving the connection request message, the AP instantiates a new virtual AP secured with the pair of SSID and password, which is dedicated to that single user device. This virtual network is securer because the password is not shared among users. It is more convenient because the network adapts itself to the user device. Experiments show that these advantages are obtained with negligible degradation in the throughput performance.