• Structural Engineering and Mechanics
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• 제53권5호
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• pp.867-880
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• 2015

Mechanical fastening is still one of the main methods used for joining components. Different techniques have been applied to reduce the effect of stress concentration of notches like fastener holes. In this work we evaluate the feasibility of combining laser shock peening (LSP) and cold expansion to improve fatigue crack initiation and propagation of open hole specimens made of 6061-T6 aluminum alloy. LSP is a new and competitive technique for strengthening metals, and like cold expansion, induces a compressive residual stress field that improves fatigue, wear and corrosion resistance. For LSP treatment, a Q-switched Nd:YAG laser with infrared radiation was used. Residual stress distribution as a function of depth was determined by the contour method. Compact tension specimens with a hole at the notch tip were subjected to LSP process and cold expansion and then tested under cyclic loading with R=0.1 generating fatigue cracks on the hole surface. Fatigue crack initiation and growth is analyzed and associated with the residual stress distribution generated by both treatments. It is observed that both methods are complementary; cold expansion increases fatigue crack initiation life, while LSP reduces fatigue crack growth rate.

• 유통과학연구
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• 제12권10호
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• pp.5-9
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• 2014

Purpose - This paper aims to critically examine capital market developments in India before and after liberalization. Research design, data, and methodology - The paper examines the Indian capital market from its inception to the latest developments related to both primary and secondary markets, and also discusses recent initiatives of capital markets to enhance the expected level of services to the investor community. It also sheds light on the regulatory framework for investor protection. Results - The study further highlights the future roadmap for the radical development of the Indian capital market. The paper identifies the various initial obstacles and intricacies that affect the smooth functioning of the Indian capital markets. Hence, the paper articulates that these concerns should be addressed by the regulatory authorities and at the policy level at the earliest for further strengthening the capital markets in the interests of the economy in general and retail investors in particular. Conclusion - This is a topic of utmost contemporary importance to worldwide national economies, and calls for novel methods and techniques in dealing effectively with the menace facing capital markets.

• 정보보호학회논문지
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• 제23권6호
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• pp.1037-1047
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• 2013

피싱(phishing) 공격의 피해가 증가함에 따라 그에 대한 대응책 및 관련 연구가 활발히 진행되어 왔다. 피싱 공격을 막는 솔루션(anti-phishing solutions)들은 웹브라우져(web-browser)의 보안 기능으로 혹은 보안 툴바(toolbar)의 형태로 다양하게 개발되었고, 그밖에도 이메일 필터링(email-filtering), 비밀 이미지 공유를 통한 서버 인증 강화 등의 방식으로 솔루션들이 개발되었다. 피싱 관련 연구로는 피싱 공격이 성공하는 이유에 대한 분석 연구, 피싱 공격을 막는 솔루션들이 효과적인지에 대해 사용자 입장에서 분석한 연구들이 발표되었다. 이 논문에서는 피싱 공격을 막는 다양한 종류의 솔루션들을 소개하고, 대표적인 솔루션들의 기술적 원리를 이해한다. 또한, 피싱 관련 연구 결과들을 함께 짚어봄으로써 피싱 공격을 막는 솔루션들이 개선되어야할 점들을 강조하여 살펴보고, 앞으로 피싱을 막기 위한 대책 연구가 진행되어야할 방향을 제시한다.

• Child Health Nursing Research
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• 제23권4호
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• pp.515-524
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• 2017

Purpose: The study was undertaken to see whether the culturally sensitive education for perinatal care using a face to face approach improves understanding of spouse's culture, knowledge of pregnancy and parenting skills, and self-efficacy among Korean husbands and Vietnamese wives. Methods: This study has a pre- and post-test study design conducted in a total of 13 couples who live in Seoul and agreed to participate. The education program consisted of lecture and hands on practice. The self-administered questionnaires and the checklist developed based on the educational purpose were used to assess the education effects. Results: The knowledge scores on Korean/Vietnamese culture, pregnancy and parenting skills as well as the performance scores on hand washing, pelvic strengthening, feedings and newborn bathing techniques were significantly improved in both husbands and wives after education, but pelvic floor exercises were improved only in wives. Conclusion: Overall, the individual education for culturally sensitive perinatal care was effective in our study participants.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.4021-4037
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• 2018

In network intrusion detection research, two characteristics are generally considered vital to building efficient intrusion detection systems (IDSs): an optimal feature selection technique and robust classification schemes. However, the emergence of sophisticated network attacks and the advent of big data concepts in intrusion detection domains require two more significant aspects to be addressed: employing an appropriate big data computing framework and utilizing a contemporary dataset to deal with ongoing advancements. As such, we present a comprehensive approach to building an efficient IDS with the aim of strengthening academic anomaly detection research in real-world operational environments. The proposed system has the following four characteristics: (i) it performs optimal feature selection using information gain and branch-and-bound algorithms; (ii) it employs machine learning techniques for classification, namely, Logistic Regression, Naïve Bayes, and Random Forest; (iii) it introduces bulk synchronous parallel processing to handle the computational requirements of large-scale networks; and (iv) it utilizes a real-time contemporary dataset generated by the Information Security Centre of Excellence at the University of Brunswick (ISCX-UNB) to validate its efficacy. Experimental analysis shows the effectiveness of the proposed framework, which is able to achieve high accuracy, low computational cost, and reduced false alarms.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.227-236
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• 2002

The purpose of this study makes a retrofit and rehabilitation practice trough the analysis and the improvement for the underlying problem of current retrofit and rehabilitation methods. Therefore, the deterioration process, the damage cause, the condition classification, the fatigue mechanism and the applied quantity of strengthening methods for RC deck slabs were analyzed. Artificial neural networks are efficient computing techniques that are widely used to solve complex problems in many fields. In this study, a back-propagation neural network model for estimating a management on existing reinforced concrete bridge decks from damage cause, damage type, and integrity assessment at the initial stage is need. The training and testing of the network were based on a database of 36. Four different network models were used to study the ability of the neural network to predict the desirable output of increasing degree of accuracy. The neural networks is trained by modifying the weights of the neurons in response to the errors between the actual output values and the target output value. Training was done iteratively until the average sum squared errors over all the training patterns were minimized. This generally occurred after about 5,000 cycles of training.

• 한국군사과학기술학회지
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• 제12권1호
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• pp.70-79
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• 2009

Currently, the investment on Research and Development(R&D) for defense core technology is continuously increasing to maintain advanced country's R&D level. In accordance with this trend, the national defense R&D investment management system is being more strengthening, and importance of performance evaluation is being emphasized more and more. However, the existing indicators of performance evaluation for defense core technology R&D is limited in efficient management because of the qualitative evaluation items and subjective allocation of points. In this paper, we developed a novel indicator for defense core technology R&D performance evaluation through domestic and foreign related literature and inquiry, brainstorming, and analysis techniques by Stepwise Multiple linear Regression(SMR) and Analytic Hierarchy Process(AHP). And we verified effectiveness of proposed indicators of performance evaluation by comparing with the existing evaluation indicators. Our proposed indicators for performance evaluation will create superiority performance on defense R&D fields.

• Steel and Composite Structures
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• 제22권6호
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• pp.1337-1358
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• 2016

The current study focuses on the assessment and interface response of reinforced concrete elements with composite materials (carbon fiber reinforced polymers-CFRPs, glass fiber reinforced polymers-GFRPs, textile reinforced mortars-TRM's, near surface mounted bars-NSMs). A description of the transfer mechanisms from concrete elements to the strengthening materials is conducted through analytical models based on failure modes: plate end interfacial debonding and intermediate flexural crack induced interfacial debonding. A database of 55 in total reinforced concrete columns (scale 1:1) is assembled containing elements rehabilitated with various techniques (29 wrapped with CFRP's, 5 wrapped with GFRP's, 4 containing NSM and 4 strengthened with TRM). The failure modes are discussed together with the performance level of each technique as well as the efficiency level in terms of ductility and bearing/ bending capacity. The analytical models' results are in acceptable agreement with the experimental data and can predict the failure modes. Despite the heterogeneity of the elements contained in the aforementioned database the results are of high interest and point out the need to incorporate the analytical expressions in design codes in order to predict the failure mechanisms and the limit states of bearing capacities of each technique.

• 한국안전학회지
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• 제23권6호
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• pp.131-137
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• 2008

SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.

• Earthquakes and Structures
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• 제16권3호
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• pp.279-293
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• 2019

The overall seismic performance of existing pre 1960-70s reinforced concrete (RC) structures is significantly affected by the inadequate length of columns' lap-spliced reinforcement. Due to this crucial structural deficiency, the cyclic response is dominated by premature bond - slip failure, strength and stiffness degradation, poor energy dissipation capacity and low ductility. Recent earthquakes worldwide highlighted the importance of improving the load transfer mechanism between lap-spliced bars, while it was clearly demonstrated that the failure of lap splices may result in a devastating effect on structural integrity. Extensive experimental and analytical research was carried out herein, to evaluate the effectiveness and reliability of strengthening techniques applied to RC columns with lap-spliced reinforcement and also accurately predict the columns' response during an earthquake. Ten large scale cantilever column subassemblages, representative of columns found in existing pre 1970s RC structures, were constructed and strengthened by steel or RC jacketing. The enhanced specimens were imposed to earthquake-type loading and their lateral response was evaluated with respect to the hysteresis of two original and two control subassemblages. The main variables examined were the lap splice length, the steel jacket width and the amount of additional confinement offered by the jackets. Moreover, an analytical formulation proposed by Tsonos (2007a, 2019) was modified appropriately and applied to the lap splice region, to calculate shear stress developed in the concrete and predict if yielding of reinforcement is achieved. The accuracy of the analytical method was checked against experimental results from both the literature and the experimental work included herein.