• Title/Summary/Keyword: specific theory

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Mechanical buckling analysis of hybrid laminated composite plates under different boundary conditions

  • Belkacem, Adim;Tahar, Hassaine Daouadji;Abderrezak, Rabahi;Amine, Benhenni Mohamed;Mohamed, Zidour;Boussad, Abbes
    • Structural Engineering and Mechanics
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    • v.66 no.6
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    • pp.761-769
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    • 2018
  • In this paper, we study the Carbon/Glass hybrid laminated composite plates, where the buckling behavior is examined using an accurate and simple refined higher order shear deformation theory. This theory takes account the shear effect, where shear deformation and shear stresses will be considered in determination of critical buckling load under different boundary conditions. The most interesting feature of this new kind of hybrid laminated composite plates is that the possibility of varying components percentages, which allows us for a variety of plates with different materials combinations in order to overcome the most difficult obstacles faced in traditional laminated composite plates like (cost and strength). Numerical results of the present study are compared with three-dimensional elasticity solutions and results of the first-order and the other higher-order theories issue from the literature. It can be concluded that the proposed theory is accurate and simple in solving the buckling behavior of hybrid laminated composite plates and allows to industrials the possibility to adjust the component of this new kind of plates in the most efficient way (reducing time and cost) according to their specific needs.

Housing Adjustment As a Symptom of Housing Dissatisfaction: Call for an Integrated Approach to Theory Building

  • Lee, Do Young
    • Architectural research
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    • v.2 no.1
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    • pp.35-40
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    • 2000
  • Housing Adjustment is a set of creative human activities that take place to meet various housing needs. Thus far, numerous studies have given attention to speculate a typology of those activities on an empirical base. Overall, though, little is known about its theoretical underpinning, due to the independent nature of each individual study in interpreting differences in conclusions. This study examines and compares results from two previous studies on housing adjustment. Previous research on housing adjustment suggests that, other than household and housing characteristics, housing satisfaction as an intervening variable is deeply associated with the choice of housing adjustment involved in mobility, home improvement, or cognitive adaptation. The two studies used similar theoretical schemes, asked similar questions, yet one sample consisted of Korean American residents and the other sample was poor housing residents in Korea. This study shows that differences in sample characteristics lead to a strong discrepancy in interpreting Speare's (1974) satisfaction theory of housing adjustment. For Korean Americans, housing satisfaction turned out to be a good predictor of housing adjustment preference, while it is not the case for poor housing residents in Korea. This implies that findings of any Single study can not be generalized directly to the population as a whole. Thus, continued effort should be made to compare specific findings from various research studies, seeking explanations for differences in conclusions. Theory can be legitimately built and strengthened in this integrated manner.

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The Disease Management Experience of Patients with Asthma: Grounded Theory Approach (천식 환자의 질병관리 경험: 근거이론접근)

  • Kim, Bohye;Kim, Oksoo
    • Journal of Korean Academy of Nursing
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    • v.50 no.5
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    • pp.714-727
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    • 2020
  • Purpose: The aim of this study was to develop a situation-specific theory to explain the disease management experience of patients with asthma. Methods: Twenty participants with asthma were selected using the theoretical sampling method. The data were acquired through in-depth interviews conducted from June to October 2018 and analyzed using the grounded theory approach of Strauss and Corbin. Results: In total, 69 concepts, 30 subcategories, and 13 categories were generated to explain the disease management experience of patients with asthma. The core category of the disease management experience of patients with asthma was 'management of the disease to prevent aggravation of symptoms over the lifetime'. The disease management process of asthma patients included three steps: the 'cognition phase', the 'adjustment phase', and the 'maintenance phase'. However, some patients remained in the 'stagnation phase' of disease management, which represents the result of the continual pursuit of risky health behavior. There were three types of disease management experiences among patients with asthma: 'self-managing', 'partially self-managing', and 'avoidant'. Conclusion: This study shows that patients with asthma must lead their disease management process to prevent exacerbation of their symptoms. It is imperative to develop nursing strategies and establish policies for effective disease management of patients with asthma based on their individual disease management processes and types.

Modeling of stress corrosion crack growth and lifetime of pipe grade high density polyethylene by using crack layer theory (Crack Layer 이론을 이용한 배관용 고밀도 폴리에틸렌의 응력부식균열 진전 및 수명 예측 모델)

  • Wee, Jung-Wook;Choi, Byoung-Ho
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.11 no.2
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    • pp.45-50
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    • 2015
  • In many cases, the field fracture mechanism of the thermoplastic pipe is considered as either brittle or environmental fractures. Thus the estimation of the lifetime by modeling slow crack growth considering such fracture mechanisms is required. In comparison of the some conventional and empirical equations to explain the slow crack growth rate such as the Paris' law, the crack layer theory can be used to simulate the crack and process zone growth behaviors precisely, so the lifetime of thermoplastic pipe can also be accurately estimated. In this study, the modified crack layer theory for the stress corrosion cracking (SCC) of high density polyethylene is introduced with detailed algorithm. The oxidation induction time of the HDPE is also considered for the reduction of specific fracture energy during exposed to chemical environments. Furthermore, the parametric study for an important SCC parameter is conducted to understand the slow crack growth behavior of SCC.

New development of artificial record generation by wavelet theory

  • Amiri, G. Ghodrati;Ashtari, P.;Rahami, H.
    • Structural Engineering and Mechanics
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    • v.22 no.2
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    • pp.185-195
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    • 2006
  • Nowadays it is very necessary to generate artificial accelerograms because of lack of adequate earthquake records and vast usage of time-history dynamic analysis to calculate responses of structures. According to the lack of natural records, the best choice is to use proper artificial earthquake records for the specified design zone. These records should be generated in a way that would contain seismic properties of a vast area and therefore could be applied as design records. The main objective of this paper is to present a new method based on wavelet theory to generate more artificial earthquake records, which are compatible with target spectrum. Wavelets are able to decompose time series to several levels that each level covers a specific range of frequencies. If an accelerogram is transformed by Fourier transform to frequency domain, then wavelets are considered as a transform in time-scale domain which frequency has been changed to scale in the recent domain. Since wavelet theory separates each signal, it is able to generate so many artificial records having the same target spectrum.

Passive shape control of force-induced harmonic lateral vibrations for laminated piezoelastic Bernoulli-Euler beams-theory and practical relevance

  • Schoeftner, J.;Irschik, H.
    • Smart Structures and Systems
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    • v.7 no.5
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    • pp.417-432
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    • 2011
  • The present paper is devoted to vibration canceling and shape control of piezoelastic slender beams. Taking into account the presence of electric networks, an extended electromechanically coupled Bernoulli-Euler beam theory for passive piezoelectric composite structures is shortly introduced in the first part of our contribution. The second part of the paper deals with the concept of passive shape control of beams using shaped piezoelectric layers and tuned inductive networks. It is shown that an impedance matching and a shaping condition must be fulfilled in order to perfectly cancel vibrations due to an arbitrary harmonic load for a specific frequency. As a main result of the present paper, the correctness of the theory of passive shape control is demonstrated for a harmonically excited piezoelelastic cantilever by a finite element calculation based on one-dimensional Bernoulli-Euler beam elements, as well as by the commercial finite element code of ANSYS using three-dimensional solid elements. Finally, an outlook for the practical importance of the passive shape control concept is given: It is shown that harmonic vibrations of a beam with properly shaped layers according to the presented passive shape control theory, which are attached to an resistor-inductive circuit (RL-circuit), can be significantly reduced over a large frequency range compared to a beam with uniformly distributed piezoelectric layers.

Digital Application of Intangible Cultural Heritage from the Perspective of Cultural Ecology

  • Jing, Xiuli;Tan, Fang;Zhang, Mu
    • Journal of Smart Tourism
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    • v.1 no.1
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    • pp.41-52
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    • 2021
  • This paper explored the digital application of intangible cultural heritage from the perspective of cultural ecology. Through field investigations, combined with cultural ecology theory, an ontology-based semantic web technology was proposed, and Nanjing "Yunjin" brocade weaving technique was selected as the research object. The specific steps were as follows: First, based on the field surveys and cultural ecology theory, the intangible cultural ecological environment was divided into natural and social environments. Next, constructing the intangible cultural heritage ontology was constructed, including the collection and collation of Nanjing Yunjin weaving technique knowledge corpus, based on user needs analysis and corpus analysis, CIDOC CRM was used to create rules to build the ontology. Finally, based on the MediaWiki platform and Semantic MediaWiki, the semantic web model of the intangible cultural heritage was designed, and its semantic retrieval function was realized, thereby achieving the practical application of intangible cultural heritage digitization. Based on the perspective of cultural ecology, a set of intangible digital application models was proposed, which expanded the digital application of the cultural ecology theory, verified the application of this model in the sustainable development of cultural tourism, and provided reference for the sustainable development of cultural tourism.

A Study on the Effectiveness of Engineering Theory Class Applying Review Games (복습게임을 활용한 공학이론 수업의 효과성 분석)

  • Kim, Gi Dae;Han, Anna
    • Journal of Engineering Education Research
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    • v.25 no.6
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    • pp.38-46
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    • 2022
  • In order to improve students' interest, class participation and class comprehension in engineering theory classes, a class applying review games as Jinjinga, Bingo, etc. were designed and developed. Through applying them to three engineering theory subjects, the specific effects of the strategy on students' understanding, interest, participation, and academic achievement were analyzed and the usefulness of each review game strategy was analyzed. Analyzing class data over the past 11 years, there was a clear correlation between performance of the students in the review game and their actual grades, which was found to be greater than the negative effect of absence rate on the test performance or grades. This study also researched students' perceptions compared to other general subjects not applying the review games. The results of a survey of the students who took the review game class showed the usual amount of usual studying hours increased, the burden of examination or the amount of studying hours for preparing the exam was reduced, and the class interest and achievement significantly increased compared to other subjects in the same major.

Why Do People Spread Online Rumors? An Empirical Study

  • Jong-Hyun Kim;Gee-Woo Bock;Rajiv Sabherwal;Han-Min Kim
    • Asia pacific journal of information systems
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    • v.29 no.4
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    • pp.591-614
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    • 2019
  • With the proliferation of social media, it has become easier for people to spread rumors online, which can aggravate the issues arising from online rumors. There are many individuals and organizations that are adversely affected by malicious online rumors. Despite their importance, there has been little research into why and how people spread rumors online, thus inhibiting the understanding of factors that affect the spreading of online rumors. With attention seeking to address this gap, this paper draws upon the dual process theory and the de-individuation theory to develop a theoretical model of factors affecting the spreading of an online rumor, and then empirically tests it using survey data from 211 individuals about a specific rumor. The results indicate that the perceived credibility of the rumor affects the individuals' attitudes toward spreading it, which consequently affects the rumor spreading behavior. Vividness, confirmation of prior beliefs, argument strength, and source credibility positively influence the perceived credibility of online rumors. Finally, anonymity moderates the relationship between attitude toward spreading online rumors and the spreading behavior.

Scientists' Information Behavior for Bridging the Gaps Encountered in the Process of the Scientific Research Lifecycle (과학기술분야 연구활동 단계별 문제상황 극복을 위한 정보행동 연구)

  • Lee, Jung-Yeoun;Chung, Eun-Kyung;Kwon, Na-Hyun
    • Journal of the Korean Society for information Management
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    • v.29 no.3
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    • pp.99-122
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    • 2012
  • This study analyzed scientists information behaviors when they engage in solving specific research problems in various situations throughout the entire scientific R&D lifecycle process. In-depth interviews with a total of 24 scientists were conducted in their research laboratories, the scientists' everyday workplace and the contexts of scientific research. The theoretical and methodological frameworks employed for this study were Dervin's Sense-making, Savolainen's Everyday Life Information Seeking, and Engestrom's Activity Theory. The findings of this study informed context-specific research and information behaviors of the scientists in the 14 sub stages of the five-stage of R&D lifecycle. Specifically, the study revealed the research objectives and related information behaviors (e.g., information needs, information seeking, information sources and channels, information barriers, etc.) to achieve the objectives at each sub-stage. The study results provided essential information to re-design the information services and strategies that accommodate the scientific R&D lifecycle.