• Title/Summary/Keyword: Civil & Environmental Engineering

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Factors affecting hydraulic anisotropy of soil

  • Nurly Gofar;Alfrendo Satyanaga;Gerarldo D. Aventian;Gulnur Pernebekova;Zhanat Argimbayeva;Sung-Woo Moon;Jong Kim
    • Geomechanics and Engineering
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    • v.36 no.4
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    • pp.343-353
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    • 2024
  • The hydraulic anisotropic behavior of unsaturated soil has not been fully explored in relation to the grain-size distribution. The present study conducted laboratory assessments to examine the hydraulic anisotropy condition of statically compacted specimens in various initial states. The investigation incorporated the concept of hydraulic anisotropy by employing two discrete forms of soil stratification: horizontal-layering (HL) and vertical-layering (VL). The examined soils comprised sandy silt and silty sand, exhibiting either unimodal or bimodal soil-water characteristic curve (SWCC). This study aimed to investigate the potential correlation between the hydraulic anisotropy ratio and soil properties. The present study established a correlation between the hydraulic anisotropy ratio and several soil parameters, including fine content, dry density, plastic limit, and liquid limit. The study results indicate a non-linear relationship between the percentage of fine and dry density in soils with unimodal and bimodal soil-water characteristic curve (SWCC) and hydraulic anisotropy ratio.

Flexible smart sensor framework for autonomous structural health monitoring

  • Rice, Jennifer A.;Mechitov, Kirill;Sim, Sung-Han;Nagayama, Tomonori;Jang, Shinae;Kim, Robin;Spencer, Billie F. Jr.;Agha, Gul;Fujino, Yozo
    • Smart Structures and Systems
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    • v.6 no.5_6
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    • pp.423-438
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    • 2010
  • Wireless smart sensors enable new approaches to improve structural health monitoring (SHM) practices through the use of distributed data processing. Such an approach is scalable to the large number of sensor nodes required for high-fidelity modal analysis and damage detection. While much of the technology associated with smart sensors has been available for nearly a decade, there have been limited numbers of fulls-cale implementations due to the lack of critical hardware and software elements. This research develops a flexible wireless smart sensor framework for full-scale, autonomous SHM that integrates the necessary software and hardware while addressing key implementation requirements. The Imote2 smart sensor platform is employed, providing the computation and communication resources that support demanding sensor network applications such as SHM of civil infrastructure. A multi-metric Imote2 sensor board with onboard signal processing specifically designed for SHM applications has been designed and validated. The framework software is based on a service-oriented architecture that is modular, reusable and extensible, thus allowing engineers to more readily realize the potential of smart sensor technology. Flexible network management software combines a sleep/wake cycle for enhanced power efficiency with threshold detection for triggering network wide operations such as synchronized sensing or decentralized modal analysis. The framework developed in this research has been validated on a full-scale a cable-stayed bridge in South Korea.

Immobilization of oxidative enzymes onto Cu-activated zeolite to catalyze 4-chlorophenol decomposition

  • Zol, Muhamad Najmi Bin;Shuhaimi, Muhammad Firdaus Bin;Yu, Jimin;Lim, Yejee;Choe, Jae Wan;Bae, Sungjun;Kim, Han S.
    • Membrane and Water Treatment
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    • v.11 no.3
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    • pp.195-200
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    • 2020
  • In this study, a biocatalyst composite was prepared by immobilizing oxidoreductases onto Cu-activated zeolite to facilitate biochemical decomposition of 4-chlorophenol (4-CP). 4-CP monooxygenase (CphC-I) was cloned from a 4-CP degrading bacterium, Pseudarthrobacter chlorophenolicus A6, and then overexpressed and purified. Type X zeolite was synthesized from non-magnetic coal fly ash using acetic acid treatment, and its surfaces were coated with copper ions via impregnation (Cu-zeolite). Then, the recombinant oxidative and reductive enzymes were immobilized onto Cu-zeolite. The enzymes were effectively immobilized onto the Cu-zeolite (79% of immobilization yield). The retained catalytic activity of CphC-I after immobilization was 0.3423 U/g-Cu-zeolite, which was 63.3% of the value of free enzymes. The results of this study suggest that copper can be used as an effective enzyme immobilization binder because it provides favorable metalhistidine binding between the enzyme and Cu-zeolite.