• KIPS Transactions on Computer and Communication Systems
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• v.4 no.4
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• pp.135-140
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• 2015

The WDSS improves defensive capacity against web application layer DDoS attack by using web cache server and L7 switch which are added on the DDoS shelter system. When web DDoS attack occurs, security agents divert traffic from backbone network to sub-network of the WDSS and then DDoS protection device and L7 switch block abnormal packets. In the meantime, web cache server responds only to requests of normal clients and maintains stable web service. In this way, the WDSS can counteract the web DDoS attack which generates small traffic and depletes server-client session resource. Furthermore, the WDSS does not require IP tunneling because it is not necessary to retransfer the normal requests to original web server. In this paper, we validate operation of the WDSS and verify defensive capability against web application layer DDoS attacks. In order to do this, we built the WDSS on backbone network of an ISP. And we performed web DDoS tests by using a testing system that consists of zombie PCs. The tests were performed by three types and various amounts of web DDoS attacks. Test results suggest that the WDSS can detect small traffic of the web DDoS attacks which do not have repeat flow whereas the formal DDoS shelter system cannot.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.6
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• pp.502-510
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• 2009

Multiprecision squaring is one of the most significant algorithms in the core public key cryptography operation. The aim of this work is to present a new improved squaring algorithm compared with the MIRACL's multi precision squaring algorithm in which the previous work [1] on multiprecision multiplication is implemented. First, previous works on multiprecision multiplication and standard squaring are analyzed. Then, our new Lazy Doubling squaring algorithm is introduced. In MIRACLE library [3], Scott's Carry-Catcher Hybrid multiplication technique [1] is applied to implementation of multiprecision multiplication and squaring. Experimental results of the Carry-Catcher hybrid squaring algorithm and the proposed Lazy Doubling squaring algorithm both of which are tested on Atmega128 CPU show that proposed idea has achieved significant performance improvements. The proposed Lazy Doubling Squaring algorithm reduces addition instructions by the fact $a_0\;{\ast}\;2\;+\;a_1\;{\ast}\;2\;+\;...\;+\;a_{n-1}\;{\ast}\;2\;+\;a_n\;{\ast}\;2\;=\;(a_0\;+\;a_1\;+\;...\;+\;a_{n-1}\;+\;a_n)\;{\ast}\;2$ while the standard squaring algorithm reduces multiplication instructions by the fact $S_{ij}\;=\;x_i\;{\ast}\;x_j\;=\;S_{ij}$. Experimental results show that the proposed squaring method is 25% faster than that in MIRACL.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.396-403
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• 2009

An anonymous asymmetric fingerprinting protocol combined with watermarking techniques, is one of the copyright protection technologies keeping both right of a seller and that of a buyer, where a seller and an anonymous buyer perform such a protocol that employs various cryptographic tools in order that the seller does not know the exact watermarked copy that the buyer receives, while inserting an invisible non-removable fingerprint i.e., each different unique watermark, into each copy of the digital content to be sold. In such a protocol innocent buyers are kept anonymous during transactions, however, the unlawful reseller is unambiguously identified with a real identity as a copyright violator. In 2007, Yong and Lee proposed an anonymous asymmetric fingerprinting scheme with trusted third party. In this paper we point out the weakness of their scheme such as: the buyer with intention can remove the fingerprint in the watermarked content, because he/she can decrypt the encrypted fingerprint with a symmetric key using man-in-the-middle-attack; a real identity of a buyer can be revealed to the seller through the identification process even though he/she is honest. Furthermore, we propose an improved secure and efficient anonymous asymmetric fingerprinting scheme which enables to reduce the number of communication between the participants.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.157-163
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• 2017

The object segmentation approach has the merit of reducing the processing cost required to detect moths of interest, because it applies a moth detection algorithm to the segmented objects after segmenting the objects individually in the moth image. In this paper, an object segmentation method for moth detection in pheromone trap images is proposed. Our method consists of preprocessing, thresholding, morphological filtering, and object labeling processes. Thresholding in the process is a critical step significantly influencing the performance of object segmentation. The proposed method can threshold very elaborately by reflecting the local properties of the moth images. We performed thresholding using global and local versions of Ostu's method and, used the proposed method for the moth images of Carposina sasakii acquired on a pheromone trap placed in an orchard. It was demonstrated that the proposed method could reflect the properties of light and background on the moth images. Also, we performed object segmentation and moth classification for Carposina sasakii images, where the latter process used an SVM classifier with training and classification steps. In the experiments, the proposed method performed the detection of Carposina sasakii for 10 moth images and achieved an average detection rate of 95% of them. Therefore, it was shown that the proposed technique is an effective monitoring method of Carposina sasakii in an orchard.

• Journal of KIISE:Databases
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• v.32 no.5
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• pp.473-486
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• 2005

The Hippocratic database model recently proposed by Agrawal et at. incorporates privacy protection capabilities into relational databases. The authors have subsequenty proposed the Hippocratic XML daかabase model[4], an extension of the Hippocratic database model for XML databases. In this paper, we propose a new concept that we cail the dynamic predicate(DP) for effective access control in the Hippocratic XML database model. A DP is a novel concept that represents a dynamically constructed rendition that tan be adapted for determining the accessibility of elements during query execution. DPs allow us to effectively integrate authorization checking into the query plan so that unauthorized elements are excluded in the process of query execution. Using synthetic and real data, we have performed extensive experiments comparing query processing time with those of existing access control mechanisms. The results show that the proposed access control mechanism improves the wall clock time by up to 219 times over the top-down access control strategy and by up to 499 times over the bottom-up access control strategy. The major contribution of our, paper is enabling effective integration of access control mechanisms with the query plan using the DP under the Hippocratic XML database model.

• Journal of Digital Convergence
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• v.15 no.5
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• pp.13-25
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• 2017

The purpose of this study is to suggest the direction of O2O industry policy for solving the conflict problems with the traditional industry stakeholder and for enhancing the regulations as new industry development is inevitable. We make use of TAIDA that is one of scenario methods to accomplish the purpose and suggest the direction of policy. First, it is needed to prepare directly by government the environment that new business models are able to emerge easily with various consulting services and information supports like public system servers and IT infra, it is practical support policy. Second, positive legal application for new business and making the law for new business are needed in legal issues situation as soon as possible. Third, the conflicts with old and new industry would be managed to the direction of "predictable" progressively. Incongruity among laws, safety and security problems, and the conflict of stakeholder are urgent. Because of the limit in this study, it is expected that O2O industry is categorized in detail aligned to the characteristics and that new policies along to the separate industry areas are developed by the following study.

• Journal of Korean society of Dental Hygiene
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• v.11 no.5
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• pp.671-683
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• 2011

Objectives : The purpose of this study was to examine the oral health knowledge and actual oral health care of the selected subjects, their decision making about prosthetic treatment, the state and characteristics of their prosthetic treatment and their satisfaction with prosthetic treatment in an attempt to provide some information on the improvement of the quality of life related to oral health and the promotion of oral health. Methods : The subjects in this study were 250 people who received education in two different lifelong education institutions in the city of Busan. After a survey was conducted from May 23 to June 15, 2011, the answer sheets from 217 respondents were analyzed. Results : 1. As for the general characteristics of the respondents, the men(52.1%) outnumbered the women. Those who were in their 60 and up(47.5%) made up the largest age group, and the married people(65.4%) outnumbered the unmarried ones. By occupation, the company employees(20.3%) made up the biggest group. By education, the greatest group was high-school graduates(36.1%). By monthly mean income, the biggest group gained an income of 2.01 million won or more(36.9%). As to medical security, community-based insurance was most prevailing (36.9%). In terms of health promotion, the largest group worked out to stay fit(52.4%). 2. Regarding oral health knowledge, they had a good knowledge about the cause of dental caries(56.7%), but they weren't well aware of the right time for regular dental checkup(47.9%). In relation to oral health care, regular scaling wasn't prevailing(16.9%). 3. Regarding connections between the general characteristics and satisfaction with prosthesis, the less-educated respondents expressed significantly more dissatisfaction(p=0.015). By monthly mean income, those who had a smaller income were dissatisfied in general(p=0.028). Conclusions : The findings of the study illustrated that it's required to spread awareness of the importance of oral health among people in general, and that differentiated incremental oral health care should be provided for different age groups. In order to raise the satisfaction of patients with prosthesis, how to relieve their pain and anxiety and how to adjust prosthetic treatment cost properly should carefully be considered. In addition, the government should take measures to offer assistance for the low-income classes in preparation for an increase in the elderly population.

• Korean Journal of Remote Sensing
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• v.35 no.6_4
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• pp.1391-1401
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• 2019

The KOMPSAT-3A is a high-resolution optical satellite launched in 2015 by Korea Aerospace Research Institute (KARI). KOMPSAT-3A provides Panchromatic (PAN-0.55 m), Multispectral (MS-2.2 m), and Mid-wavelength infrared (MIR_OR-5.5 m) image. However, due to security or military problems, MIR_OR image with 5.5m spatial resolution are provided down sampled at 33 m spatial resolution (MIR_rd). In this study, we propose spatial sharpening method to improve the spatial resolution of MIR_rd image (33 m) using virtual High Frequency (HF) image and optimal fusion factor. Using MS image and MIR_rd image, we generated virtual high resolution (5.5 m) MIR_OR^fus image and then compared them to actual high-resolution MIR_OR image. The test results show that the proposed method merges the spatial resolution of MS image and the spectral information of MIR_rd image efficiently.

• Journal of Internet Computing and Services
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• v.18 no.2
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• pp.21-30
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• 2017

IoT(Internet of Things) can enable networking and computing using any devices is rapidly proliferated. In the existing IoT environment, bottlenecks and service delays can occur because it processes data and provides services to users using central processing based on Cloud. For this reason, Edge Computing processes data directly in IoT nodes and networks to provide the services to the users has attracted attention. Also, numerous researchers have been attracted to intelligent service efficiently based on Edge Computing. In this paper, expert system-based context awareness scheme for Edge Computing in IoT environment is proposed. The proposed scheme can provide customized services to the users using context awareness and process data in real-time using the expert system based on efficient cooperations of resource limited IoT nodes. The context awareness services can be modified by the users according to the usage purpose. The three service modes in the security system based on smart home are used to test the proposed scheme and the stability of the proposed scheme is proven by a comparison of the resource consumptions of the servers between the proposed scheme and the PC-based expert system.

• Journal of Korea Water Resources Association
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• v.49 no.3
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• pp.187-196
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• 2016

Standardized Precipitation Evapotranspiration Index (SPEI) considering evapotranspiration and precipitation is generally used to quantify the drought severity. Also, Reconnaissance Drought Index (RDI) has been frequently used in the arid regions which is suffering severe droughts, but drought analysis in association with RDI has been the focus of few studies in South Korea. Therefore, this study compared two meterological drought indices based on precipitation and evapotranspiration using Thornthwaite, Hargreaves, and Blaney-Criddle evaportranspiration calculation methods. Meteorological data of sixteen weather stations which are operated by Korea Meteorological Administration (KMA) were used to quantify drought and to compare characteristics of drought for the Han River Basin from 1992 to 2015. As a result, in case of Han River Basin, severe drought sharply increased in recent years. While the correlation coefficients are relatively high between the SPEIs and RDIs, the drought severity and year of severe drought are partially different. Therefore, it is necessary that RDI will be also measured to quantify severity and occurrence year of drought.