• Title/Summary/Keyword: new material model

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New Hollow RC Bridge Piers with Triangular Reinforcement Details (삼각망 철근상세를 갖는 새로운 중공 철근콘크리트 교각)

  • Kim, Tae-Hoon;Kim, Ho-Young;Lee, Jae-Hoon;Shin, Hyun-Mock
    • Journal of the Earthquake Engineering Society of Korea
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    • v.20 no.1
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    • pp.21-31
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    • 2016
  • This study investigates the seismic performance of new hollow reinforced concrete (RC) bridge piers with triangular reinforcement details. The developed triangular reinforcement details are economically feasible and rational, and facilitate shorter construction periods. We tested a model of new hollow RC bridge piers with triangular reinforcement details under a constant axial load and a quasi-static, cyclically reversed horizontal load. We used a computer program, Reinforced Concrete Analysis in Higher Evaluation System Technology (RCAHEST), for analysis of RC structures. The used numerical method gives a realistic prediction of seismic performance throughout the loading cycles for several hollow pier specimens investigated. As a result, developed triangular reinforcement details for material quantity reduction was equal to existing reinforcement details in terms of required performance.

A Comparative Analysis of Fuzzy Logic-Based Relaying and Wavelet-Based Relaying for Large Transformer Protection (대용량 변압기 보호용 퍼지논리 계전기법과 웨이브렛 계전기법의 비교 분석)

  • Park, Chul-Won;Park, Jae-Sae;Shin, Myong-Chul
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.52 no.4
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    • pp.179-188
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    • 2003
  • Percentage differential characteristic scheme has been recognized as the principal basis for large transformer protection. Nowadays, relaying signals can contain second harmonic component to a large extent even in a normal state, and second harmonic ratio indicates a tendency of relative reduction because of the advancement of transformer's core material. And then, conventional second harmonic restraint differential relaying exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for the effective and accurate discrimination. This paper deals with advanced fuzzy logic based relaying by using flux differential, and a new fault detection criterion logic scheme by using wavelet transform. To comparative analysis of proposed techniques, the paper constructs power system model including power transformer, utilizing the EMTP, and collects data through simulation of various internal faults and magnetizing inrush. The proposed fuzzy relaying and a new fault detection scheme were tested. The former, fuzzy relaying, was proven to be faster and more reliable than the latter.

A Study on a New Concept for the Structural Strength Assessment to Development of Membrane LNG Cargo Container System under Static Load (멤브레인형 LNG 화물창 개발을 위한 정적 구조 안전성 평가 모델 연구)

  • Hwang, Se Yun;Kim, Yooil;Kang, Joong Kyoo;Lee, Jang Hyun
    • Journal of the Society of Naval Architects of Korea
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    • v.53 no.2
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    • pp.162-169
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    • 2016
  • A new concept of membrane type LNG CCS was proposed. Also, its static behavior was numerically analyzed considering the interaction between primary and secondary barrier together with securing device. Hull deflection was taken into account as an external load, together with temperature distribution across the barriers. The suggested numerical model considers both sliding and contact between the two mating surfaces of both the primary and secondary barrier, and anisotropic material behavior of plywood, R-PUF was also taken into account. Furthermore, detailed local strength was evaluated for the securing device, which is arranged between two barriers to hold the primary barrier. It was confirmed through the numerical analysis that the new concept of membrane type CCS was structurally safe under static loading condition and securing concept was structurally reliable.

Improvement of the osteogenic potential of ErhBMP-2-/EGCG-coated biphasic calcium phosphate bone substitute: in vitro and in vivo activity

  • Hwang, Jae-ho;Oh, Seunghan;Kim, Sungtae
    • Journal of Periodontal and Implant Science
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    • v.49 no.2
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    • pp.114-126
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    • 2019
  • Purpose: The aim of this study was to evaluate the enhancement of osteogenic potential of biphasic calcium phosphate (BCP) bone substitute coated with Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2) and epigallocatechin-3-gallate (EGCG). Methods: The cell viability, differentiation, and mineralization of osteoblasts was tested with ErhBMP-2-/EGCG solution. Coated BCP surfaces were also investigated. Standardized, 6-mm diameter defects were created bilaterally on the maxillary sinus of 10 male New Zealand white rabbits. After removal of the bony windows and elevation of sinus membranes, ErhBMP-2-/EGCG-coated BCP was applied on one defect in the test group. BCP was applied on the other defect to form the control group. The animals were sacrificed at 4 or 8 weeks after surgery. Histologic and histometric analyses of the augmented graft and surrounding tissue were performed. Results: The 4-week and 8-week test groups showed more new bone (%) than the corresponding control groups (P<0.05). The 8-week test group showed more new bone (%) than the 4-week test group (P<0.05). Conclusions: ErhBMP-2-/EGCG-coated BCP was effective as a bone graft material, showing enhanced osteogenic potential and minimal side effects in a rabbit sinus augmentation model.

Development of New Processes for the Decommissioning Decontamination and for Treatment and Disposal of the Secondary Low- and Intermediate-Level Radioactive Waste

  • John, Jan;Bartl, Pavel;Cubova, Katerina;Nemec, Mojmir;Semelova, Miroslava;Sebesta, Ferdinand;Sobova, Tereza;Sul'akova, Jana;Vetesnik, Ales;Vopalka, Dusan
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.19 no.1
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    • pp.9-27
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    • 2021
  • As an example of research activities in decontamination for decommissioning, new data are presented on the options for corrosion layer dissolution during the decommissioning decontamination, or persulfate regeneration for decontamination solutions re-use. For the management of spent decontamination solutions, new method based on solvent extraction of radionuclides into ionic liquid followed by electrodeposition of the radionuclides has been developed. Fields of applications of composite inorganic-organic absorbers or solid extractants with polyacrylonitrile (PAN) binding matrix for the treatment of liquid radioactive waste are reviewed; a method for americium separation from the boric acid containing NPP evaporator concentrates based on the TODGA-PAN material is discussed in more detail. Performance of a model of radionuclide transport, developed and implemented within the GoldSim programming environment, for the safety studies of the LLW/ILW repository is demonstrated on the specific case of the Richard repository (Czech Republic). Continuation and even broadening of these activities are expected in connection with the approaching end of the lifespan of the first blocks of the Czech NPPs.

Nature and Changes of Southeast Asian Maritime Trade in 15-16 Century: Focused on Portuguese Contact and Influences (15-16세기 동남아 해상무역의 특성과 변화: 포르투갈의 진출과 영향을 중심으로)

  • Kim, Dong-Yeob
    • The Southeast Asian review
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    • v.21 no.2
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    • pp.1-41
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    • 2011
  • Southeast Asia developed maritime trade from the early period due to the suitable physical and cultural conditions. The land consists of peninsular and archipelago, and located at the junction of the two monsoons in South China Sea and India Ocean. The people inherit cultural openness to receive outer influences positively. When Portuguese came to Southeast Asia in 16th century, the region had already enjoyed certain level of commercial development and sociocultural dynamics through the long time experience of interactions with outer world. The Portuguese contact to Southeast Asia was more of participation and assimilation than of conquest and rule experienced in South America. It was due to the higher level of spiritual and material civilization existed in Southeast Asia. Portuguese brought several new elements into Southeast Asia such as colonization and new weapons, Cartaz system and commercial monopoly, and Catholic mission and Casado policy. These new elements, however, did not impact much on the existing Maritime trade that played an important role to change the sociocultural structure of Southeast Asia. Even though Portuguese contact itself did not make significant differences in Southeast Asia, it was meaningful in a sense that it opened a path and left a model case for the more powerful Europeans who came soon after her.

A new refined hyperbolic shear deformation theory for laminated composite spherical shells

  • Kada, Draiche;Abdelouahed, Tounsi
    • Structural Engineering and Mechanics
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    • v.84 no.6
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    • pp.707-722
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    • 2022
  • In this study, a new refined hyperbolic shear deformation theory (RHSDT) is developed using an equivalent single-layer shell displacement model for the static bending and free vibration response of cross-ply laminated composite spherical shells. It is based on a new kinematic in which the transverse displacement is approximated as a sum of the bending and shear components, leading to a reduction of the number of unknown functions and governing equations. The proposed theory uses the hyperbolic shape function to account for an appropriate distribution of the transverse shear strains through the thickness and satisfies the boundary conditions on the shell surfaces without requiring any shear correction factors. The shell governing equations for this study are derived in terms of displacement from Hamilton's principle and solved via a Navier-type analytical procedure. The validity and high accuracy of the present theory are ascertained by comparing the obtained numerical results of displacements, stresses, and natural frequencies with their counterparts generated by some higher-order shear deformation theories. Further, a parametric study examines in detail the effect of both geometrical parameters (i.e., side-to-thickness ratio and curvature-radius-to-side ratio), on the bending and free vibration response of simply supported laminated spherical shells, which can be very useful for many modern engineering applications and their optimization design.

Application of computer methods in music composition using smart nanobeams

  • Ying Shi;Maryam Shokravi;X. Chen
    • Advances in nano research
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    • v.17 no.3
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    • pp.285-291
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    • 2024
  • The paper considers one of the new applications of computer methods in music composition, using smart nanobeams-an integration of advanced computational techniques with new, specially designed materials for enhanced performance capabilities in music composition. The research applies some peculiar properties of smart nanobeams, embedded with piezoelectric materials that modulate and control sound vibrations in real-time. The study is conducted to determine the effects of changes in the length, thickness of nanobeams and the applied voltage on acoustical properties and the tone quality of musical instruments with the help of numerical simulations and optimization algorithms. By means of piezo-elasticity theory, different governing equations of nanobeam systems can be derived, which are solved by the numerical method to predict the dynamic behavior of the system under different conditions. Results show that manipulation of the parameters allows great control over pitch, timbre, and resonance of the instrument; such a system offers new ways in which composers and performers can create music. This research also validates the computational model against available theoretical data, proving the accuracy and possible applications of the former. The work thus marks a large step towards the intersection of music composition with smart material technology, and, when further developed, it would mean that smart nanobeams could revolutionize the process for composing and performing music on these instruments.

Confined concrete model of circular, elliptical and octagonal CFST short columns

  • Patel, Vipulkumar I.;Uy, Brian;Prajwal, K.A.;Aslani, Farhad
    • Steel and Composite Structures
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    • v.22 no.3
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    • pp.497-520
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    • 2016
  • The confined concrete stress-strain curves utilised in computational models of concrete-filled steel tubular (CFST) columns can have a significant influence on the accuracy of the predicted behaviour. A generic model is proposed for predicting the stress-strain behaviour of confined concrete in short circular, elliptical and octagonal CFST columns subjected to axial compression. The finite element (FE) analysis is carried out to simulate the concrete confining pressure in short circular, elliptical and octagonal CFST columns. The concrete confining pressure relies on the geometric and material parameters of CFST columns. The post-peak behaviour of the concrete stress-strain curve is determined using independent existing experimental results. The strength reduction factor is derived for predicting the descending part of the confined concrete behaviour. The fibre element model is developed for the analysis of circular, elliptical and octagonal CFST short columns under axial loading. The FE model and fibre element model accounting for the proposed concrete confined model is verified by comparing the computed results with experimental results. The ultimate axial strengths and complete axial load-strain curves obtained from the FE model and fibre element model agree reasonably well with experimental results. Parametric studies have been carried out to examine the effects of important parameters on the compressive behaviour of short circular, elliptical and octagonal CFST columns. The design model proposed by Liang and Fragomeni (2009) for short circular, elliptical and octagonal CFST columns is validated by comparing the predicted results with experimental results.

A Study on the Improvement of Measuring Method for Density of Model Ice (모형빙 밀도 계측 방법 개선 연구)

  • Ha, Jung-Seok;Kang, Kuk-Jin;Cho, Seong-Rak;Jeong, Seong-Yeob;Lee, Chun-Ju
    • Journal of the Society of Naval Architects of Korea
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    • v.52 no.2
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    • pp.104-109
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    • 2015
  • The Korea Research Institute of Ships & Ocean Engineering (KRISO) has an ice tank to make a test environment similar to the real ice in the polar sea in order to carry out model tests. One of the most important task of the ice tank is to generate the model ice to have similar material properties as sea ice. The primary properties of sea ice which influence the ice performance of ice breakers and ice-strengthened vessels traveling in the polar sea are ice thickness, flexural strength, density, modulus of elasticity and crystal structure etc. Among them, since the density of model ice influences the buoyance resistance of ice for the ship model, the accurate measurement of ice density should be used to obtain the accurate analysis results from the model test. In this paper, some existing methods to measure the density of model ice are reviewed and a new one is proposed to measure it accurately and easily as possible. In this study, the measuring system including an UTM and several measuring devices was established to obtain the model ice density. Polyethylene and ice specimens are used for a series of repeatable measurement tests. From the results, it was recognized that both of the displacement method and the weight/weight methods gave the stable and favorable tendency.