• BMB Reports
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• 제44권1호
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• pp.22-27
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• 2011

A series of elastin-like proteins, $SKGPG[V(VKG)_3VKVPG]_n$-(ELP1-90)WP (n = 1, 2, 3, and 4), were biosynthesized based on the hydrophobic and lysine linkage domains of tropoelastin. The formation of self-assembled hydrophobic aggregates was monitored in order to determine the influence of cationic segments on phase transition properties as well as the sensitivity to changes in salt and pH. The thermal transition profiles of the proteins fused with only one or two cationic blocks (n = 1 or 2) were similar to that of the counterpart ELP1-90. In contrast, diblock proteins that contain 3 and 4 cationic blocks displayed a triphasic profile and no transition, respectively. Upon increasing the salt concentration and pH, a stimulus-induced phase transition from a soluble conformation to an insoluble aggregate was observed. The effects of cationic segments on the stimuli sensitivity of cationic bimodal ELPs were interpreted in terms of their structural and molecular characteristics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.537-537
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• 2012

We have studied a fabrication of vapor phase polymerized Poly(3,4-ethylenedioxythiophene) (PEDOT) nanowire arrays for the first time. The vapor-phase polymerization (VPP) technique is a bottom-up processing method that utilizes the organic arrangement of macromolecules to easily produce ordered aggregates, including on the nanoscale, or prepare thin films of self-assembled molecules, micropatterns, or modified microstructures of pure conducting polymers. Also, liquid-bridge-mediated nanotransfer molding (LB-nTM), which was reported as a new direct patterning method recently, is for the arrayed formation of two- or three-dimensional structures with feature sizes as small as tens of nanometers over large areas up to 4 inches across and is based on the direct transfer of various materials from a mould to a substrate through a liquid bridge between them. The PEDOT nanowires grown by VPP method and transferred on a substrate to use LB-nTM method have been fabricated to single crystal PEDOT nanowires investigated Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and electrical properties.

• Journal of Dairy Science and Biotechnology
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• 제33권2호
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• pp.139-151
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• 2015

Biofilms are aggregates of microorganisms present in a self-produced matrix of extracellular polymeric substance (EPS) adhered to a surface. Formation of a biofilm in the environment on farms and in dairy plants comprises several stages: attachment, growth (development), and detachment. Generally, biofilms are harmful to humans and need to be controlled. Stainless steel (SS) surfaces that are untreated or are scratched comprise substrata that are especially vulnerable to biofilm formation; therefore, SS surfaces should be polished and sanitized. Various approaches are available for the destruction of biofilms; cleaning-in-place (CIP) is the method mainly used in dairy plants. Further study on optimum detergents, cleaning conditions, and methods for this purpose is needed.

• 한국건설순환자원학회논문집
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• 제4권3호
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• pp.69-74
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• 2009

This paper summarizes the analysis of granite microfines from California for use in portland cement concrete. For reference, the granite microfines were compared to microfines used in previous International Center for Aggregates Research(ICAR) projects. The particle shape characteristics, based on the packing density results, were assessed and apparent clay content, based on the methylene blue value test, was evaluated. Also, the physical properties of the microfines were confirmed in self-consolidating mortar mixtures.

• Computers and Concrete
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• 제23권6호
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• pp.399-408
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• 2019

Structural health monitoring is important for the safety of lives and asset management. In this study, numerical models were developed for the piezoresistive behavior of smart concrete based on finite element (FE) method. Finite element models were calibrated with experimental data collected from compression test. The compression test was performed on smart concrete cube specimens with 75 mm dimensions. Smart concrete was made of cement CEM II 42.5 R, silica fume, fine and coarse crushed limestone aggregates, brass fibers and plasticizer. During the compression test, electrical resistance change and compressive strain measurements were conducted simultaneously. Smart concrete had a strong linear relationship between strain and electrical resistance change due to its piezoresistive function. The piezoresistivity of the smart concrete was modeled by FE method. Twenty-noded solid brick elements were used to model the smart concrete specimens in the finite element platform of Ansys. The numerical results were determined for strain induced resistivity change. The electrical resistivity of simulated smart concrete decreased with applied strain, as found in experimental investigation. The numerical findings are in good agreement with the experimental results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.365-368
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• 2008

최근, 하천에서 얻을 수 있는 자연모래의 부족과 환경 보호에 대한 요구 등으로 인해 잔골재로써의 부순 모래가 콘크리트 산업에서 사용이 증가되고 있다. 골재는 자기충전 모르타르(SCM)를 포함한 자기 충전 콘크리트(SCC)의 특성에 큰 영향을 준다. 잔골재로 부순 모래를 사용한 SCC와 SCM의 유동적 특성을 자연 모래를 사용한 것과 두 가지를 섞은 모래를 사용한 SCC와 SCM과 비교 하였다. 실험결과는 50% 섞인 모래가 포함된 SCM의 yield stress가 SP 함유량에 따른 자연 모래와 부순 모래보다 높다는 것을 보여준다. 자연모래 SCC의 슬럼프 값은 부순 모래의 SCC보다 거의 5-15% 높다. 또한 같은 물/시 멘트비와 증점제에서 자연모래 SCC의 L-box test 값은 부순 모래 SCC보다 거의 20-30% 높다.

• International Journal of Concrete Structures and Materials
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• 제3권1호
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• pp.3-9
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• 2009

This paper examines the incorporation of the crushed sand (CS) and desert sand (DS) in the formation of self compacting concrete (SCC). These sands have been substituted for the rolled sand (RS), which is currently the only sand used in concretes and which is likely to run out in our country. DS, which comes from the Tunisian Sahara in the south, is characterized by a tight distribution of grains size. CS, a by-product of careers containing a significant amount of fines up to 15%, is characterized by a spread out granulometry having a maximum diameter of around 5mm. These two sands are considered as aggregates for the SCC. This first part of the study consists in analyzing the influence of the type of sand on the parameters of composition of the SCC. These sands consist of several combinations of 3 sands (DS, CS and RS). The method of formulation of the adopted SCC is based on the filling of the granular void by the paste. The CS substitution to the RS made it possible, for all the proportions, to decrease the granular voids, to increase the compactness of the mixture and to decrease the water and adding fillers proportioning. These results were also obtained for a moderate substitution of DS/CS (< 40%) and a weak ratio of DS/RS (20%). For higher proportions, the addition of DS to CS or RS did not improve the physical characteristics of the SCC granular mixture.

• Advances in concrete construction
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• 제13권6호
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• pp.433-450
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• 2022

The conventional disposal methods of waste tires are harmful to the environment. Moreover, the recycling/reuse of waste tires in domestic and industrial applications is limited due to parent product's quality control and environmental concerns. Additionally, the recycling industry often prefers powdered rubber particles (<0.60 mm). However, the processing of waste tires yields both powdered and coarser (>0.60 mm) size fractions. Reprocessing of coarser rubber requires higher energy increasing the product cost. Therefore, the waste tire rubber (WTR) less favored by the recycling industry is encouraged for use in construction products as one of the environment-friendly disposal methods. In this study, WTR fiber >0.60 mm size fraction is collected from the industry and sorted into 0.60-1.18, 1.18-2.36-, and 2.36-4.75-mm sizes. The effects of different fiber size fractions are studied by incorporating it as fine aggregates at 10%, 20%, and 30% in the self-compacting rubberized concrete (SCRC). The experimental investigations are carried out by performing fresh and hardened state tests. As the fresh state tests, the slump-flow, T500, V-funnel, and L-box are performed. As the hardened state tests, the scanning electron microscope, compressive strength, flexural strength and split tensile strength tests are conducted. Also, the water absorption, porosity, and ultrasonic pulse velocity tests are performed to measure durability. Furthermore, SCRC's energy absorption capacity is evaluated using the falling weight impact test. The statistical significance of content and size fraction of WTR fiber on SCRC is evaluated using the analysis of variance (ANOVA). As the general conclusion, implementation of various size fraction WTR fiber as fine aggregate showed potential for producing concrete for construction applications. Thus, use of WTR fiber in concrete is suggested for safe, and feasible waste tire disposal.

• Advances in concrete construction
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• 제16권1호
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• pp.35-57
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• 2023

Majority of the plastic produced each year is being disposed in land after single-use, which becomes waste and takes up a lot of storage space. Therefore, there is an urgent need to find alternative solutions instead of disposal. Recycling and reusing the PET plastic waste as aggregate replacement and fiber in concrete production can be one of the eco- friendly methods as there is a great demand for concrete around the world, especially in developing countries by raising human awareness of the environment, the economy, and Carbon dioxide (CO2) emissions. Self-compacting concrete (SCC) is a key development in concrete technology that offers a number of attractive features over traditional concrete applications. Recently, in order to improve its durability and prevent such plastics from directly contacting the environment, various kinds of plastics have been added. This review article summarizes the latest evident on the performance of SCC containing recycled PET as eco-friendly aggregates and fiber. Moreover, it highlights the influence of substitution content, shape, length, and size on the fresh and properties of SCC incorporating PET plastic. Based on the findings of the articles that were reviewed for this study, it is observed that SCC made of PET plastic (PETSCC) can be employed in construction era owing to its acceptable mechanical and fresh properties. On the other hand, it is concluded that owing to the lightweight nature of plastic aggregate, Reusing PET waste in the construction application is an effective approach to reduces the earthquake risk of a building.

• 한국건설순환자원학회논문집
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• 제9권3호
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• pp.383-388
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• 2021

본 연구에서는 정수위 투수시험을 통하여 무기계 치유소재를 사용한 자기치유 모르타르의 치유성능을 평가하였다. 자기치유 모르타르의 제조를 위해 무기계 소재로 고로슬래그 미분말, 황산나트륨, 무수석고를 사용하였으며, 시멘트 클링커 분말과 클링커 잔골재를 시멘트와 잔골재를 각각 대체하여 사용하였다. 정수위 투수시험을 수행하여 균열폭과 치유재령 경과에 따른 단위유출 수량을 측정하였다. 자기치유 모르타르의 치유성능평가 결과 Plain 모르타르와 비교하여 치유재령 28일에서 초기 균열폭이 0.3mm인 경우 치유율이 30%p 이상 증가하여 치유성능이 크게 증진된 것을 확인하였다. 또한, 투수시험결과로부터 얻은 상수(α)를 이용하여 치유재령 경과에 따른 등가균열폭을 산출하였으며, 등가균열폭과 치유율의 상관관계 분석을 통해 치유 목표균열폭을 만족하기 위한 초기 균열폭과 도달시기를 예측하였다.