• Title/Summary/Keyword: plastic features

Search Result 391, Processing Time 0.022 seconds

Damage Detecion of CFRP-Laminated Concrete based on a Continuous Self-Sensing Technology (셀프센싱 상시계측 기반 CFRP보강 콘크리트 구조물의 손상검색)

  • Kim, Young-Jin;Park, Seung-Hee;Jin, Kyu-Nam;Lee, Chang-Gil
    • Land and Housing Review
    • /
    • v.2 no.4
    • /
    • pp.407-413
    • /
    • 2011
  • This paper reports a novel structural health monitoring (SHM) technique for detecting de-bonding between a concrete beam and CFRP (Carbon Fiber Reinforced Polymer) sheet that is attached to the concrete surface. To achieve this, a multi-scale actuated sensing system with a self-sensing circuit using piezoelectric active sensors is applied to the CFRP laminated concrete beam structure. In this self-sensing based multi-scale actuated sensing, one scale provides a wide frequency-band structural response from the self-sensed impedance measurements and the other scale provides a specific frequency-induced structural wavelet response from the self-sensed guided wave measurement. To quantify the de-bonding levels, the supervised learning-based statistical pattern recognition was implemented by composing a two-dimensional (2D) plane using the damage indices extracted from the impedance and guided wave features.

Feasibility Study on Diagnosis of Material Damage Using Bulk Wave Mixing Technique (체적파 혼합기법을 이용한 재료 손상 진단 적용 가능성 연구)

  • Choi, Jeongseok;Cho, Younho
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.36 no.1
    • /
    • pp.53-59
    • /
    • 2016
  • Ultrasonic nonlinear evaluation is generally utilized for detection of not only defects but also microdamage such as corrosion and plastic deformation. Nonlinearity is determined by the amplitude ratio of primary wave second harmonic wave, and the results of its comparison are used for evaluation. Owing to the experimental features, the experimental nonlinearity result contains system nonlinearity and material nonlinearity. System nonlinearity is that which is unwanted by the user; hence, it acts as an error and interrupts analysis. In this study, a bulk wave mixing technique is implemented in order to minimize the system nonlinearity and obtain the reliable analysis results. The biggest advantage of this technique is that experimental nonlinearity contains less system nonlinearity than that for the conventional nonlinear ultrasonic technique. Theoretical and experimental verifications are performed in this study. By comparing the results of the bulk wave mixing technique with those of the conventional technique, the strengths, weaknesses, and application validity of the bulk wave mixing technique are determined.

Effect of PCE superplasticizers on rheological and strength properties of high strength self-consolidating concrete

  • Bauchkar, S.D.;Chore, H.S.
    • Advances in concrete construction
    • /
    • v.6 no.6
    • /
    • pp.561-583
    • /
    • 2018
  • A variety of polycarboxylate ether (PCE)-based superplasticizers are commercially available. Their influence on the rheological retention and slump loss in respect of concrete differ considerably. Fluidity and slump loss are the cardinal features responsible for the quality of concrete. These are related to the dispersion of cement particles and the hydration process which are greatly influenced by type of polycarboxylate ether (PCE)-based superplasticizers. On the backdrop of relatively less studies in the context of rheological retention of high strength self-consolidating concrete (HS-SCC), the experimental investigations were carried out aiming at quantifying the effect of the six different PCE polymers (PCE 1-6) on the rheological retention of HS-SCC mixes containing two types of Ordinary Portland Cements (OPC) and unwashed crushed sand as the fine aggregate. The tests that were carried out included $T_{500}$, V-Funnel, yield stress and viscosity retention tests. The supplementary cementitious materials such as fly ash (FA) and micro-silica (MS) were also used in ternary blend keeping the mix paste volume and flow of concrete constant. Low water to binder ratio was used. The results reveal that not only the PCEs of different polymer groups behave differently, but even the PCEs of same polymer groups also behave differently. The study also indicates that the HS-SCC mixes containing PCE 6 and PCE 5 performed better as compared to the mixes containing PCE 1, PCE 2, PCE 3 and PCE 4 in respect of all the rheological tests. The PCE 6 is a new class of chemical admixtures known as Polyaryl Ether (PAE) developed by BASF to provide better rheological properties in even in HS-SCC mixes at low water to binder mix. In the present study, the PCE 6, is found to help not only in reduction in the plastic viscosity and yield stress, but also provide good rheological retention over the period of 180 minutes. Further, the early compressive strength properties (one day compressive strength) highly depend on the type of PCE polymer. The side chain length of PCE polymer and the fineness of the cement considerably affect the early strength gain.

An Experimental Study on the Mechanical Mounting between GFRP Door Impact Beam and Steel Brackets (GFRP 도어 임팩트 빔과 Steel 브래킷의 기계적 결합에 관한 실험적 연구)

  • Ha, Jung-Chan;Shin, Young-cheol;Baek, In-Seok;Lee, Seok-Soon
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.20 no.5
    • /
    • pp.103-110
    • /
    • 2021
  • The mounting performance of the GFRP(Glass fiber Reinforced Plastic) beam and the mechanical mounting of the steel bracket was studied to be mounted as a GFRP impact beam on the side door of the passenger car. Moreover, an open-hole tensile test was performed to evaluate breakage tendency based on GFRP stacking conditions. Furthermore, the tightening strength of rivets and bolts was compared using the single lap-shear tension test for the GFRP stacking pattern. Additionally, the GFRP beam and bracket mounting features were designed; moreover, the prototype and bracket were assembled. Additionally, the bracket mounting bending test and the door assembly static bending test were performed to verify the stability of the bracket mounting. In the bracket fastening bending test, no breakage occurred in the connection part between the GFRP beam and the bracket, and it showed 67% (24.4 kN) improved performance compared to steel. In the static bending test of the door assembly, the initial average reaction force increased by 25% compared to the steel, and the performance of all FMVSS-214 regulations was satisfied. The replacement of GFRP impact beams resulted in a 30% weight reduction

Using Artificial Neural Network in the reverse design of a composite sandwich structure

  • Mortda M. Sahib;Gyorgy Kovacs
    • Structural Engineering and Mechanics
    • /
    • v.85 no.5
    • /
    • pp.635-644
    • /
    • 2023
  • The design of honeycomb sandwich structures is often challenging because these structures can be tailored from a variety of possible cores and face sheets configurations, therefore, the design of sandwich structures is characterized as a time-consuming and complex task. A data-driven computational approach that integrates the analytical method and Artificial Neural Network (ANN) is developed by the authors to rapidly predict the design of sandwich structures for a targeted maximum structural deflection. The elaborated ANN reverse design approach is applied to obtain the thickness of the sandwich core, the thickness of the laminated face sheets, and safety factors for composite sandwich structure. The required data for building ANN model were obtained using the governing equations of sandwich components in conjunction with the Monte Carlo Method. Then, the functional relationship between the input and output features was created using the neural network Backpropagation (BP) algorithm. The input variables were the dimensions of the sandwich structure, the applied load, the core density, and the maximum deflection, which was the reverse input given by the designer. The outstanding performance of reverse ANN model revealed through a low value of mean square error (MSE) together with the coefficient of determination (R2) close to the unity. Furthermore, the output of the model was in good agreement with the analytical solution with a maximum error 4.7%. The combination of reverse concept and ANN may provide a potentially novel approach in designing of sandwich structures. The main added value of this study is the elaboration of a reverse ANN model, which provides a low computational technique as well as savestime in the design or redesign of sandwich structures compared to analytical and finite element approaches.

Seismic Performance Evaluation of Dry Precast Concrete Beam-Column Connections With Intermediate Moment Frame Details (중간모멘트골조 상세를 갖는 건식 프리캐스트 콘크리트 보-기둥 접합부의 내진성능평가)

  • Kim, Seon Hoon;Cho, Jong;Oh, Hyo Keun;Choi, Seok Dong;Yeo, Un Yong;Lee, Deuck Hang
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.27 no.3
    • /
    • pp.129-137
    • /
    • 2023
  • This study presents a dry precast concrete (PC) beam-column connection, and its target seismic performance level is set to be emulative to the reinforced concrete (RC) intermediate moment resisting frame system specified in ACI 318 and ASCE 7. The key features include self-sustaining ability during construction with the dry mechanical splicing method, enabling emulative connection performances and better constructability. Test specimens with code-compliant seismic details were fabricated and tested under reversed cyclic loading, which included a PC beam-column connection specimen with dry connections and an RC control specimen. The test results showed that all the specimens failed in a similar failure mode due to plastic deformations in beam members, while the hysteretic response curve of the PC specimen showed comparable and emulative performances compared to the RC specimen. Seismic performance evaluation was quantitatively addressed, and on this basis, it confirmed that the presented system can fully satisfy all the required performance for the intermediate RC moment resisting frame.

Earthquake Response Analysis of a RC Bridge Including the Effect of Repair/retrofitting (보수/보강 효과를 고려한 철근콘크리트교량의 내진응답해석)

  • Lee, Do Hyung;Cho, Kyu Sang;Jeon, Jeong Moon
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.28 no.4A
    • /
    • pp.611-622
    • /
    • 2008
  • Nonlinear analyses have been carried out for both bridge piers and a bridge structure being repaired using a repair element in order to assess the post-repair seismic response of such structures. For this purpose, a simplified CFRP stress-strain model has been proposed. The analytical predictions incorporating the current developments correlate reasonably well with experimental results in terms of strength and stiffness. In addition, nonlinear dynamaic analyses have also been conducted for a bridge structure in terms of the created multiple earthquake sets to evaluate the effect of pier repair on the response of a whole bridge structure. In these analyses, potential plastic hinge zones of piers are virtually repaired by CFRP and steel jacketing. Comparative results prove the virtual necessity of performing nonlinear post-repair analyses under multiple earthquakes, particularly when the post-repair response features are required. In all, the present approaches are expected to provide salient information regarding a healthy seismic repair intervention of a damaged strcuture.

A Study on Art's Public Features and Social Intervention by Keith Haring (미술의 공공성과 키스 해링(Keith Haring)의 사회적 개입에 관한 연구)

  • Kim, Jee-Young
    • The Journal of Art Theory & Practice
    • /
    • no.8
    • /
    • pp.59-87
    • /
    • 2009
  • This thesis started from the attempt to make it clear that 80's American artist Keith Haring(1958-1990) had conducted social intervention of criticism, resistance, and participation through his works, and so pursued public value. Haring of graffiti fame left popular and familiar cartoon style pictures on the street wall, the billboards, the posters and so on. Popular and playful works was explained as his unique characteristics, but Haring's creative way at the field has more value than just being grasped as artist's personal characteristics. Haring's work pieces became everyday art by joining with people's life, and are working as a social speaking place. So I think that these Haring's art works possess characteristics of 'the public sphere'. 'The Public Sphere' means that is independent and free from the government or partisan economic forces, so that is not connected with the interested relations, and that is the sphere of rational argumentation without 'disguise' or 'fabrication', and that is the sphere where general public can participate in and is inspected by them. The public sphere between the sphere of public authority such a nation and a market and the private sphere of free individual, it is mutually connected with them and works as the space forming public opinion. Private individuals communicate with this public sphere and perform a role of direct and indirect check, balance, and social criticism way off from power. Openness that should include the voice of not only leading power but also the socially weak such as citizens, women, homosexuals, minority races, and so on, and alienated class, is an index of the public characteristics. The public sphere is not working just with speech and mass media. Many artists as well as Haring open their mouth and act through an art at the center of society, and create another public sphere by an art. I understood that the real participatory and practical characteristics on the Haring's work is a phenomenon and current of a part of the art world including Haring. Such current started from 1960s is the in-depth effort to be connected with the life more closely, to communicate with people, and to improve problems of life. And it has pursued public value on the different way from the nation or public power. Artists have intervened in the society with strategic and positive ways in order to raise pushed-out value and sinked rights as the public agenda, and labored to accept the value of variety and difference at the society. The aspect of such social intervention is the notable features, findable on the Haring's works and process. Haring's works include art historical meanings and are expressed with familiar and plastic language, so they were able to communicate with various classes. And he secured various customers at the field and the street. This communicative and public approach factor raised the possibility much for his works to work as the public sphere. Haring presented critical and resistant speech toward society with his works based on this factor. He asserted his position and justice of gender identity as a sexual minority. And his such work continued to movement for alienated class and social week over his own rights. His speech and message on the wall painting, poster, T-shirts, billboard of the subway, and so on worked as a spectacle and pressed concern with social issues and consciousness shift. And he's been trying to protect and care people who is injured by HIV and drug and to realize social justice through social week protection. Haring's works planned to meet many people as much as possible performed its role of intervening in society through criticism, resistance, speech, and participation, and controlling and checking social issues. These things considered, Haring's works show his consciousness about public attributes of art, and obviously include public value seeking. And also we can find the meaning of such his work as that an art is working as the public sphere and shows the possibility to discuss and practice public issues.

  • PDF

A Study of 'Emotion Trigger' by Text Mining Techniques (텍스트 마이닝을 이용한 감정 유발 요인 'Emotion Trigger'에 관한 연구)

  • An, Juyoung;Bae, Junghwan;Han, Namgi;Song, Min
    • Journal of Intelligence and Information Systems
    • /
    • v.21 no.2
    • /
    • pp.69-92
    • /
    • 2015
  • The explosion of social media data has led to apply text-mining techniques to analyze big social media data in a more rigorous manner. Even if social media text analysis algorithms were improved, previous approaches to social media text analysis have some limitations. In the field of sentiment analysis of social media written in Korean, there are two typical approaches. One is the linguistic approach using machine learning, which is the most common approach. Some studies have been conducted by adding grammatical factors to feature sets for training classification model. The other approach adopts the semantic analysis method to sentiment analysis, but this approach is mainly applied to English texts. To overcome these limitations, this study applies the Word2Vec algorithm which is an extension of the neural network algorithms to deal with more extensive semantic features that were underestimated in existing sentiment analysis. The result from adopting the Word2Vec algorithm is compared to the result from co-occurrence analysis to identify the difference between two approaches. The results show that the distribution related word extracted by Word2Vec algorithm in that the words represent some emotion about the keyword used are three times more than extracted by co-occurrence analysis. The reason of the difference between two results comes from Word2Vec's semantic features vectorization. Therefore, it is possible to say that Word2Vec algorithm is able to catch the hidden related words which have not been found in traditional analysis. In addition, Part Of Speech (POS) tagging for Korean is used to detect adjective as "emotional word" in Korean. In addition, the emotion words extracted from the text are converted into word vector by the Word2Vec algorithm to find related words. Among these related words, noun words are selected because each word of them would have causal relationship with "emotional word" in the sentence. The process of extracting these trigger factor of emotional word is named "Emotion Trigger" in this study. As a case study, the datasets used in the study are collected by searching using three keywords: professor, prosecutor, and doctor in that these keywords contain rich public emotion and opinion. Advanced data collecting was conducted to select secondary keywords for data gathering. The secondary keywords for each keyword used to gather the data to be used in actual analysis are followed: Professor (sexual assault, misappropriation of research money, recruitment irregularities, polifessor), Doctor (Shin hae-chul sky hospital, drinking and plastic surgery, rebate) Prosecutor (lewd behavior, sponsor). The size of the text data is about to 100,000(Professor: 25720, Doctor: 35110, Prosecutor: 43225) and the data are gathered from news, blog, and twitter to reflect various level of public emotion into text data analysis. As a visualization method, Gephi (http://gephi.github.io) was used and every program used in text processing and analysis are java coding. The contributions of this study are as follows: First, different approaches for sentiment analysis are integrated to overcome the limitations of existing approaches. Secondly, finding Emotion Trigger can detect the hidden connections to public emotion which existing method cannot detect. Finally, the approach used in this study could be generalized regardless of types of text data. The limitation of this study is that it is hard to say the word extracted by Emotion Trigger processing has significantly causal relationship with emotional word in a sentence. The future study will be conducted to clarify the causal relationship between emotional words and the words extracted by Emotion Trigger by comparing with the relationships manually tagged. Furthermore, the text data used in Emotion Trigger are twitter, so the data have a number of distinct features which we did not deal with in this study. These features will be considered in further study.

Effects of Curcumin on Osteoclasts (파골세포에 대한 커큐민의 효과)

  • Kim, Jeong-Joong;Kim, Dong-Joo;Lee, Byung-Ki;Kim, Kwang-Jin;Lee, Myeung-Su;Lee, Jae-Hoon;Kim, Hun-Soo;Lee, Chang-Hoon;Byun, Seung-Jae;Jang, Sung-Jo;Song, Jeong-Hoon;Oh, Jae-Min;Lee, Jun-Seok;Kim, Kwang-Mee;Chun, Churl-Hong
    • Journal of Physiology & Pathology in Korean Medicine
    • /
    • v.22 no.6
    • /
    • pp.1566-1571
    • /
    • 2008
  • Bone is a dynamic tissue that is constantly resorbed by osteoclasts and then replaced by osteoblasts. Osteoclasts, multinucleated cells of monocyte/macrophage lineage, are responsible for bone disorders, including osteoporosis and rheumatoid arthritis. In this study, we examined the effect of the curcumin on osteoclast survival and bone resorption. We found that curcumin significantly inhibited RANKL-mediated osteoclast survival. DAPI stainingrevealed that curcumin induced the apoptotic features of osteoclasts. Although curcumin did not suppress the phosphorylation of Akt and ERK in osteoclasts treated with RANKL, curcumin induced the cleavage of pro-caspase-9 and -3 its active forms. Also, curcumin inhibited the formation of actin rings of osteoclasts. RANKL-mediated bone resorption was inhibited by the addition of curcumin. Together with the results of this study, these findings suggest that the curcumin inhibited the survival of osteoclasts by activating caspase-9 and -3 and suppressed the bone resorptive activity. Thus, curcumin may be developed as antiresorptive drugs for the treatment of bone-related disorders.