• 한국IT서비스학회지
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• 제14권3호
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• pp.197-215
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• 2015

Recently, many internet users are using cloud computing. Users can manage, store and share their data and information by using personal cloud storage. In this paper, we aim to figure out influencing factors on personal cloud storage selection. The causal relationship between factors were identified through a importance analysis by using AHP(Analytic Hierarchy Process). AHP is a structured technique for organizing and analyzing complex decisions, based on mathematics and psychology. Research model consists of upper factorsincluding system factor, service factor and user factor. 12 lower factors and 6 alternatives were also analyzed. Asa result, system factor of 3 upper factors was found as the most important factor. Purpose-coincidence, security andaccessibility were top 3 factors among lower factors. N drive showed top importance value. We also conducted ANOVAby classifying 4 groups according to gender, age, currently used cloud and cloud to use. The results of this researchcan be useful guidelines for cloud computing industry.

• 대한수의학회지
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• 제60권1호
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• pp.15-18
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• 2020

Canine heartworm disease is a vector-borne disease that is transmitted from dog to dog by mosquitoes. It causes epidemics that disrupt the health environments of dogs and are burdensome for many dog owners. Recent trends of changing temperatures and weather conditions in South Korea may have an impact on the population of mosquitoes, and it affects the population of dogs at risk of heartworm infection. Mathematical modeling has become an important measure for analyzing the epidemiological characteristics of infectious diseases. However, canine heartworm infection transmission has not been reported yet through mathematical modeling. We develop a mathematical model of canine heartworm infection to predict the population of infected dogs depending on the vector (mosquito) population using a susceptible, exposed, infected, and recovered model. Simulation results show that after 1 year, 3,289 dogs out of 73,602 (about 4.5%) are exposed and 134 (about 0.2%) are infected. Only 0.2% of susceptible dogs become infected after 1 year. However, if all exposed dogs are maintained in the same circumstances without any treatment, then the number of infected subjects will increase over time. This may increase the possibility of other dogs, especially dogs that live outside, being infected.

• Smart Structures and Systems
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• 제24권4호
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• pp.553-566
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• 2019

This study aimed to categorize pervious rubberized concrete into fresh and hardened concrete analyzing its durability, permeability and strength. During the globalization of modern life, growing population and industry rate have signified a sustainable approach to all aspects of modern life. In recent years, pervious concrete (porous concrete) has significantly substituted for pavements due to its mechanical and environmental properties. On the other hand, scrap rubber tire has been also contributed with several disposal challenges. Considering the huge amount of annually tire wastes tossing out, the conditions become worse. Pervious concrete (PC) gap has graded surface assisted with storm water management, recharging groundwater sources and alleviate water run-offs. The results have shown that the use of waste tires as aggregate built into pervious concrete has tremendously reduced the scrap tire wastes enhancing environmental compliance.

• STI Policy Review
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• 제5권2호
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• pp.43-64
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• 2014

Korea has pursued an aggressive policy of inviting more foreign-born students to its universities since the late 1990s in the wake of the globalization of education markets and its changing demographic structure. While increasingly more students from Asia come to Korea for study, more than half of the graduates return home upon graduation. Given the issues of brain drain, brain circulation, and knowledge transfer that are raised by such a high return rate, this paper examines the factors that frame the foreign students' decision on their post-graduation careers. By analyzing survey data, we report that Asian students majoring in science, technology, engineering, and mathematics (STEM) are more likely to return than non-STEM majors. This suggests that Korea's aggressive policies of inviting foreign-born students have contributed to brain circulation and knowledge transfer between Korea and the other Asian countries. We also find that scholarships from Korean sources and positive attitudes toward Korean culture and life increase their inclination to stay in the country upon graduation. These findings, however, raise more questions than answers, since it becomes obvious that their post-graduation decisions are highly affected by what Korea as a society provides.

• Steel and Composite Structures
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• 제33권2호
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• pp.261-275
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• 2019

The main objective of this paper is to study the axial buckling and post-buckling of geometrically imperfect single-layer graphene sheets (GSs) under in-plane loading in the theoretical framework of the nonlocal strain gradient theory. To begin with, a graphene sheet is modeled by a two-dimensional plate subjected to simply supported ends, and supposed to have a small initial curvature. Then according to the Hamilton's principle, the nonlinear governing equations are derived with the aid of the classical plate theory and the von-karman nonlinearity theory. Subsequently, for providing a more accurate physical assessment with respect to the influence of respective parameters on the mechanical performances, the approximate analytical solutions are acquired via using a two-step perturbation method. Finally, the authors perform a detailed parametric study based on the solutions, including geometric imperfection, nonlocal parameters, strain gradient parameters and wave mode numbers, and then reaching a significant conclusion that both the size-dependent effect and a geometrical imperfection can't be ignored in analyzing GSs.

• 정보보호학회논문지
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• 제19권5호
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• pp.17-24
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• 2009

Zhang 등은 SAC'08에서 스트림 암호에 대한 향상된 고속 상관 공격을 제안하였다[8]. 이 공격은 Crypto'00에서 제안된 고속 상관 공격에 기반을 두고 FWT(fast Walsh transform)을 적용하여 설계되었다. [8]에서는 다양한 공격 환경에서 공격 알고리즘의 복잡도와 성공 확률이 제시되었지만, 제안된 공격 알고리즘을 실제 구현한 결과, 제시된 결과와 다르게 나타났다. 본 논문에서는 실험 결과를 토대로 [8]에서 제시된 공격 결과의 문제점을 분석하고, 이 공격 알고리즘이 유효하게 적용되는 bias의 threshold를 제시한다.

• International Journal of Computer Science & Network Security
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• 제21권3호
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• pp.206-211
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• 2021

Internet users are increasingly invited to express their opinions on various subjects in social networks, e-commerce sites, news sites, forums, etc. Much of this information, which describes feelings, becomes the subject of study in several areas of research such as: "Sensing opinions and analyzing feelings". It is the process of identifying the polarity of the feelings held in the opinions found in the interactions of Internet users on the web and classifying them as positive, negative, or neutral. In this article, we suggest the implementation of a sentiment analysis tool that has the role of detecting the polarity of opinions from people about COVID-19 extracted from social media (tweeter) in the Arabic language and to know the impact of the pre-processing phase on the opinions classification. The results show gaps in this area of research, first of all, the lack of resources when collecting data. Second, Arabic language is more complexes in pre-processing step, especially the dialects in the pre-treatment phase. But ultimately the results obtained are promising.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제26권2호
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• pp.45-61
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• 2023

Number talks as a brief instructional routine benefits students and teachers. In general, the routines consist of four steps- introducing, posing questions, collecting answers, sharing ideas. This paper focuses on the sharing ideas step in which multiple strategies are shared by students because teachers sometimes do not know what to do with these multiple ideas. One way is to support students to engage in comparison given that teachers are expected to support students to compare strategies in number talks. This paper explores whether and how 15 prospective teachers supported students in their practicum classroom to compare different strategies in their enacted number talk. In this paper, 15 videos of number talks enacted by the prospective teachers were collected. Analyzing the videos produced multiple episodes in relation to comparing strategies, including 1) where prospective teachers created pre-conditions for comparison, 2) where they invited students for comparison, 3) where they pressed students to compare, and 4) where they offered their own way to compare. There were two patterns that might limit the potential of having multiple strategies as conditions for comparison. Additionally, this paper found that even though the prospective teachers missed opportunities to support students to compare different strategies, there were two ways for teachers to support students to engage in comparison. These findings can be used for mathematics teacher educators to support prospective teachers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권4호
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• pp.1020-1041
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• 2024

With the development of covert communication technologies, the number of covert communication technologies using blockchain as a carrier is increasing. However, using the transaction amount of digital currency as a carrier for covert communication has problems such as low embedding rate, large consumption of transaction amount, and easy detection. In this paper, firstly, by experimentally analyzing the distribution of bitcoin transaction amounts, we determine the most suitable range of amounts for matrix decomposition. Secondly, we design a novel matrix decomposition method that can successfully decompose a large amount matrix into two small amount matrices and utilize the elements in the small amount matrices for covert communication. Finally, we analyze the feasibility of the novel matrix decomposition method in this scheme in detail from four aspects, and verify it by experimental comparison, which proves that our scheme not only improves the embedding rate and reduces the consumption of transaction amount, but also has a certain degree of resistance to detection.

• 한국과학교육학회지
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• 제34권2호
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• pp.63-78
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• 2014

통합적 STEM 교육은 과학, 기술, 공학, 수학의 내용과 과정을 체계적이고 의도적으로 통합하려는 공학적 설계기반 학습을 말하며, 다른 교과와 통합을 통해 더욱 발달할 수 있다. 이 연구는 과학 탐구 기반의 통합적 STEM 교육 프로그램의 개발과 효과 검증을 위한 기초연구이며, STEM 교육 관련 문헌 연구를 통해 STEM 교육의 가치와 핵심요소를 분석하고 과학 탐구 기반의 통합적 STEM 교육 모형의 개발 및 모형을 적용하여 개발한 대표적인 예시 프로그램을 제시하는 것이다. 모형에 포함될 요소를 확정하기 위해 문헌 분석을 실시하였고, 선행 연구에 포함된 내용과 탐구 과정을 분석하여 통합적 STEM 교육 모형을 구성하였다. 전문가의 내용 타당도 분석 결과 CVR 값의 평균은 0.78로 구성된 모형은 내용 타당도가 있는 것으로 판단되었다. 이 STEM 교육 모형은 내용과 탐구 과정의 두 가지 측면으로 나누어진다. 내용의 측면은 실생활 문제에서 경험할 수 있는 과학, 기술, 공학, 수학 그리고 인문사회와 예술적 소재까지 포괄할 수 있으며, 탐구 과정은 설계와 제작을 기반으로 한 문제해결 과정이다. 탐구 과정은 과학 탐구를 기반으로 하여 기술 공학적 문제해결 과정을 적용할 수 있도록 구성하였다. 학생들은 실생활 문제를 분석하고, 설계하고 제작하는 과정에서 STEM 교과에 대한 흥미를 향상시킬 수 있고 문제에 포함된 지식과 탐구의 방법과 기능을 체계적으로 학습할 수 있다. 개발된 프로그램은 학교 현장에서 활용되어, STEM 교과에 대한 이해도 증진과 과학, 수학에 대한 흥미를 높이고, 과학기술 기반의 융합적 소양과 설계 기반의 문제해결력을 배양하는 데 기여할 수 있을 것이다.