• Smart Structures and Systems
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• v.21 no.4
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• pp.421-433
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• 2018

Carbon fiber reinforced polymer (CFRP) cable has good mechanical properties and corrosion resistance. However, the anchorage of CFRP cable is a big issue due to the anisotropic property of CFRP material. In this article, a high-efficient bonding anchorage with novel configuration is developed for CFRP cables. The acoustic emission (AE) technique is employed to evaluate the performance of anchorage in the fatigue test and post-fatigue ultimate bearing capacity test. The obtained AE signals are analyzed by using a combination of unsupervised K-means clustering and supervised K-nearest neighbor classification (K-NN) for quantifying the performance of the anchorage and damage evolutions. An AE feature vector (including both frequency and energy characteristics of AE signal) for clustering analysis is proposed and the under-sampling approaches are employed to regress the influence of the imbalanced classes distribution in AE dataset for improving clustering quality. The results indicate that four classes exist in AE dataset, which correspond to the shear deformation of potting compound, matrix cracking, fiber-matrix debonding and fiber fracture in CFRP bars. The AE intensity released by the deformation of potting compound is very slight during the whole loading process and no obvious premature damage observed in CFRP bars aroused by anchorage effect at relative low stress level, indicating the anchorage configuration in this study is reliable.

• Journal of The Korean Association of Information Education
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• v.20 no.6
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• pp.543-552
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• 2016

Recently, a number of researches focus on social network analysis and it is applied to various fields not only in social science area but also in natural science area. Therefore, the social network analysis and the text analysis were conducted in order to analyze the current trend of the theses in information education field. The result indicated that the most frequently mentioned words were consistent with the development of information technology and the change in information education curriculum. That is, the mentioned words were computer aided instruction (CAI) and courseware for period 1, ICT for period 2, smart and scratch for period 3, and in period 4, computational thinking ability and coding appeared for the first time. Moreover, as the result of social network analysis, it concluded the research topics became more complicated and detailed as the words diversified throughout the period in which the simplified network in period 1 changed its configuration into a structure with more diversified words of higher centrality.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.921-928
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• 2016

Over the past few years, Smishing attacks such as malicious url and malicious application have been emerged as a major problem in South Korea since it caused big problems such as leakage of personal information and financial loss. Users are susceptible to Smishing attacks due to the fact that text message may contain curios content. Because of that reason, user could follow the url, download and install malicious APK file without any doubt or verification process. However currently Anti-Smishing App that adopted post-processing method is difficult to respond quickly. Users need a system that can determine whether the modification of the APK file and malicious url in real time because the Smishing can cause financial damage. This paper present the cloud-based system for verifying malicious url and malicious APK file in user device to prevent secondary damage such as smishing attacks and privacy information leakage.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.4
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• pp.141-147
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• 2018

Solar energy has attracted big attentions as one of clean and unlimited renewable energy. Solar energy is transformed to electrical energy by solar cells which are comprised of multi-silicon wafer or mono-silicon wafer. Monosilicon wafers are fabricated from the Czochralski method. In order to decrease fabrication cost, increasing a poly-silicon charge size in one quartz crucible has been developed very much. When we increase a charge size, the temperature control of a Czochralski equipment becomes more difficult due to a strong melt convection. In this study, we simulated a Czochralski equipment temperature at 20 inch and 24 inch in quartz crucible diameter and various charge sizes (90 kg, 120 kg, 150 kg, 200 kg, 250 kg). The simulated temperature profiles are compared with real temperature profiles and analyzed. It turns out that the simulated temperature profiles and real temperature profiles are in good agreement. We can use a simulated profile for the optimization of real temperature profile in the case of increasing charge sizes.

• Journal of Digital Contents Society
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• v.16 no.4
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• pp.605-613
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• 2015

This paper addresses the problem to make sparse the projection matrix in pattern recognition method. Recently, the size of computer program is often restricted in embedded systems. It is very often that developed programs include some constant data. For example, many pattern recognition programs use the projection matrix for dimension reduction. To improve the recognition performance, very high dimensional feature vectors are often extracted. In this case, the projection matrix can be very big. Recently, RSR(roated sparse regression) method[1] was proposed. This method has been proved one of the best algorithm that obtains the sparse matrix. We propose three methods to improve the RSR; outlier removal, sampling and elastic net RSR(E-RSR) in which the penalty term in RSR optimization function is replaced by that of the elastic net regression. The experimental results show that the proposed methods are very effective and improve the sparsity rate dramatically without sacrificing the recognition rate compared to the original RSR method.

• Korean Journal of Environment and Ecology
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• v.30 no.3
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• pp.415-422
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• 2016

This study measured the vitality of Pinus densiflora and Ginko biloba and analyzed the differences of vitality levels among trees based on artificial management. Research has shown that the mean value of cambial electrical resistance (CER) on Pinus densiflora was $14.9K{\Omega}$(between $8.5{\sim}37.5K{\Omega}$), and for Ginko biloba it was $13.5K{\Omega}$ (between 6.4 and $40.5K{\Omega}$). For the purpose of artificial management, over 50% of trees were covered up with soil and about 40% of trees were not protected by fence to enable growth spaces. It was seen that the CER of trees covered up with soil was significantly higher than that of trees which were not covered up with soil. These results indicate that it is necessary to remove the soil covering for effective management of monumental trees.

• Journal of the Korea Convergence Society
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• v.7 no.4
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• pp.9-17
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• 2016

This study is to analyze korea credit card market and the China credit card market, and predict future economic activity by developing the Algorithm for future economic trend Estimation As a results, there is no significant correlation between personal income growth and the credit card usage amount, and significant correlation between the credit card per capita and the credit card usage amount, in korea. there is significant correlation between personal income growth and the credit card usage amount, and between the credit card per capita and the credit card usage amount in china. it could be predicted that the china credit card market would be increased and the rate of increase would be gradually increased over the next five years, under the condition without constraints in the external environment.

• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.247-252
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• 2018

The problem of the environment is urgently coming to the world as a problem that humanity must solve. In particular, Korea is directly affected by air pollution and marine pollution due to its geopolitical position with China, and is also exposed to a great deal of pollution due to air, water, soil, and weather. In this situation, due to the disconnection between the management domain / service (system) related to the environment, the ability to quickly identify causes and cope with situations in the event of environmental pollution or disasters is weak, and duplication and investment are being faced. The development of a service platform for smart environment disaster management is designed to detect environmental disasters in an early stage through the management of smart environment disaster management at the national level, It will be a way to predict complex environmental disasters.

• The Korean Journal of Applied Statistics
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• v.31 no.4
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• pp.529-538
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• 2018

Tuberculosis causes high morbidity and mortality. However, Korea still has the highest tuberculosis (TB) incidence and mortality among OECD countries despite decreasing incidence and mortality due to the development of modern medicine. Korea has now implemented various policy projects to prevent and control tuberculosis. This study analyzes the effects of public-private mix (PPM) tuberculosis control program on treatment outcomes and identifies the factors that affecting the success of TB treatment. We analyzed 130,000 new tuberculosis patient cohort from 2012 to 2015 using data of tuberculosis patient reports managed by the Disease Control Headquarters. A cumulative incidence function (CIF) compared the cumulative treatment success rates for each factor. We compared the results of the analysis using two popular types of competition risk models (cause-specific Cox's proportional hazards model and subdistribution hazard model) that account for the main event of interest (treatment success) and competing events (death).

• Journal of Korean Library and Information Science Society
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• v.50 no.4
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• pp.359-379
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• 2019

This study aims to suggest the ways to reinforce academic library's supports for users' class·learning activities. For this purpose, this study collected the development plans of academic libraries in Korea, and analysed the plans for supporting class·learning activities. As a result, it is shown that the most libraries emphasized 'expansion of learning material' and marked it on development plan. As subsequent plans, libraries provided the action plans of 'expansion of reading education and reading programs', 'expansion of electronic materials', 'expansion of characterized materials' one after another. This study suggests 'user-centered collection development and expansion of learning materials', 'activation of library services making use of big data', 'enlargement of engagement services for handicapped and foreign students' as ways to strengthen the services of academic libraries to support class·learning activities of users.