• Advances in nano research
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• v.10 no.4
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• pp.327-337
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• 2021

In this review, composite structures are used for many industries for at least four decades. Polymeric composites are one of the important structures in the aerospace and aviation industry because of their high strength and low weight. In this comprehensive review, mechanical behaviors, physical and mechanical properties of polymeric composites, different types of reinforcements, different methods to fabricate polymeric composites, historical structural composite materials for aviation and aerospace industries, and also different methods for the characterization are reported. How to use various methods of composite preparation using different nanofillers as reinforcements and its effect on the physical properties and mechanical behavior of composites are discussed as well.

• Earthquakes and Structures
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• v.2 no.3
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• pp.233-256
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• 2011

This paper investigates the applicability of newly developed Cu-Al-Mn shape memory alloy (SMA) bars to retrofitting of historical masonry constructions by performing quasi-static tests of half-scale brick walls subjected to cyclic out-of-plane flexure. Problems associated with conventional steel reinforcing bars lie in pinching, or degradation of stiffness and strength under cyclic loading, and in their inability to restrain residual deformations in structures during and after intense earthquakes. This paper attempts to resolve the problems by applying newly developed Cu-Al-Mn SMA bars, characterized by large recovery strain, low material cost, and high machinability, as partial replacements for steel bars. Three types of brick wall specimens, unreinforced, steel reinforced, and SMA reinforced specimens are prepared. The specimens are subjected to quasi-static cyclic loading up to rotation angle enough to cause yielding of reinforcing bars. Corresponding nonlinear finite element models are developed to simulate the experimental observations. It was found from the experimental and numerical results that both the steel reinforced and SMA reinforced specimens showed substantial increment in strength and ductility as compared to the unreinforced specimen. The steel reinforced specimen showed pinching and significant residual elongation in reinforcing bars while the SMA reinforced specimen did not. Both the experimental and numerical observations demonstrate the superiority of Cu-Al-Mn SMA bars to conventional steel reinforcing bars in retrofitting historical masonry constructions.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.791-799
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• 2019

This study explained the historical changes in the habitat structures based on the aerial photographs (1948, 1967, 1973, 1989 and 2010) of the mid-stream reach of the Mangyeong River. The habitat structure was divided into landforms and aquatic habitats. The landform was classified into bare land, vegetated land, water surface, farmland and artificial land. The aquatic habitat was classified into natural riffle, artificial riffle, run, head wando, tail wando, mid wando, pond and chute channel. The ratio of bareland decreased, and water surface and vegetated land increased after the excavation in 1970s and since the construction of weir in 1980s. As historical changes of aquatic habitat, ratio of run decreased sharply while mid wando increased sharply. aquatic habitats such as head wando, tail wando, and pond located on bars decreased dramatically.

• Korean Institute of Interior Design Journal
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• v.22 no.4
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• pp.121-129
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• 2013

This study was aimed at determining the characteristics of circular multi-family housing under the assumption that the shape of a residential building affects local identity. A total of six case studies were included in this study, three case studies on idle historical industrial facilities turned into residential buildings and another three on multi-family housing located in newly developed residential complexes. The study drew its conclusions as follows. First, the design of circular multi-family housing was intended to maximize security and defense from the outside in older times. This was later developed as the terrace house style with geometric urban squares designed under the urban planning of the Baroque period. This evolved high-density housing with a courtyard in the center offering a green open space, with the aim of restoring a sense of humanity. Second, the six case studies on circular multi-family housing were analyzed from the viewpoint of each factor of local identity, including historical and cultural, landscape, and community. Third, the historical and cultural elements of circular multi-family housing are found in some unused historical industrial facilities remodeled into residential buildings. They provide new capabilities and shapes desired by society at a given time, while maintaining familiar styles and elements of history, integrating a legacy of the past into the present. Fourth, circular multi-family housing with unique shapes and structures often become landmarks of a region with their distinctive appearance against a uniform urban environment and the monotonous scenery of residential complexes. They also show a high level of visual awareness with the distinctive shapes made possible when new elements are added to a historical exterior. Finally, circular multi-family housing with courtyards in the center prompt social contact between inhabitants, especially with dormitories and rental houses for the low-income bracket, which provide a small individual units with high use common space. Circular multi-family housing are planned in a manner similar to a small village or a city. They are designed to enhance sense of community, allocating various public amenities and provide cultural and commercial spaces on the ground floor and courtyard areas.

• Journal of architectural history
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• v.23 no.2
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• pp.7-24
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• 2014

The purpose of this research is to clarify the valuable industrial heritages of rice mill industry complex remained in Incheon. In order to clarify the formation of integrated historical setting of rice mill industry of Incheon, we analyzed the old map of Incheon's old Jemulpo area and data on address, locations and happenings surrounding rice mill factories and relevant facilities. From here, we could find out the 4 representative rice mill industry area of integrated historical setting and 2 other supporting service area for rice mill industry in old city center of Incheon. Specifically, we could figure out the incremental stages to establish the rice mill industry in Incheon. In the first stage, the rice mill factories were established near foreign settlement area where trading offices and warehouses were equipped. And the second stage reflect the needs of expanding area for Japanese capitalism with the new landfill area. In the final stage, Korean rice mill owners established the korean laborers community near Korean residential area. This formation of integrated historical setting reflecting Incheon's rice mill industry is the identical industrial heritages and urban structures to show the tension and conflict between Japanese and Korean laborers' life in the Japanese Colonial Period.

• Computers and Concrete
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• v.20 no.4
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• pp.409-418
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• 2017

Turkey owns a very important cultural and historical heritage that bears the traces of thousands of years of culture and civilization. It is an inevitable duty to carry these treasuries to the future generations. In this paper, structural safety assessment and strengthening stages of one of these important historical heritages namely Amasya Taşhan was investigated in details as a case study. For this purpose, the detailed architectural projects of the structure with the information of all load carrying and structural elements were prepared. Then, the structural dynamic analyses were performed by using SAP2000. The internal forces obtained from the dynamic analyses determined the weak regions. By obtaining the information from dynamic analyses, the method of state of the art technique of application of the structure that needs structural strengthening was selected. The last step is the application of these precautions to the whole structure. At the end of this study, this study not also contains several strengthening techniques that is used in one masonry structure together but also provides a useful reference to the practicing engineers.

• Smart Structures and Systems
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• v.26 no.1
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• pp.63-75
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• 2020

Substructure pseudo-dynamic hybrid simulation (SPDHS) combining the advantages of physical experiments and numerical simulation has become an important testing method for evaluating the dynamic responses of structures. Various parameter identification methods have been proposed for online model updating. However, if there is large model gap between the assumed numerical models and the real models, the parameter identification methods will cause large prediction errors. This study presents an ANN (artificial neural network) method based on forgetting factor. During the SPDHS of model updating, a dynamic sample window is formed in each loading step with forgetting factor to keep balance between the new samples and historical ones. The effectiveness and anti-noise ability of this method are evaluated by numerical analysis of a six-story frame structure with BRBs (Buckling Restrained Brace). One BRB is simulated in OpenFresco as the experimental substructure, while the rest is modeled in MATLAB. The results show that ANN is able to present more hysteresis behaviors that do not exist in the initial assumed numerical models. It is demonstrated that the proposed method has good adaptability and prediction accuracy of restoring force even under different loading histories.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.49-52
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• 2007

Terrestrial Laser Scanning(TLS) was developed at the mid-to-late 1990s. This technique enables to perform reconnaissance surveying of regions or structures hard to access. Besides, TLS has been extended its application gradually such as preservation of historical remains, underground surveys, slopes, glaciers monitoring and so on. However, though the technique has a lot of advantages, an application for structural health and safety monitoring is a beginning stage and it need much research. Therefore in this study, as a groundwork, the estimation model on stress of structures using TLS and Finite Element Method(FEM) applied by the Digital Elevation Model(DEM) technique of geoinformatics is proposed. For the verification of this model, experiments were performed with a continuous steel beam subjected to point loads and outputs were compared with those of electrical strain sensors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.97-102
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• 1988

The strain release associated with historical and instrumental earthquoke data are analyzed. In addition, the relationship between engineering intensity and cumulative frequency of earthquake occurrence is investigated. Based on the study, a seimic zoning map of the Korean peninsula is constructed. For each seismic zone, a peak ground acceleration value is determined for the aseismic designs of two types of structures. First type is general structures like buildings and the second type is special structures like nuclear power plants.

• Journal of the Korean Society for Advanced Composite Structures
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• v.5 no.2
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• pp.27-32
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• 2014

Since the collapse of historical masonry structures in Europe in the late 1990's, the interests in understanding the long-term effect of masonry under sustained compressive stresses have increased. That requires combining the significance of time-dependent effects of creep with the effect of damage due to overstress to realize the evolution of cracks and then failure in masonry. Meanwhile, composite analysis of masonry columns was proven effective for realizing ultimate strength capacity of masonry column. In this study, a simplified mechanical model with step-by-step in time analysis was proposed to incorporate the interaction of damage and creep to estimate the maximum stress occurred in masonry. It was examined that the interaction of creep and damage in masonry can accelerate the failure of masonry.