• Structural Engineering and Mechanics
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• v.39 no.2
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• pp.187-206
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• 2011

This paper uses dynamic computer simulation techniques to develop and apply a multi-criteria procedure using non-destructive vibration-based parameters for damage assessment in truss bridges. In addition to changes in natural frequencies, this procedure incorporates two parameters, namely the modal flexibility and the modal strain energy. Using the numerically simulated modal data obtained through finite element analysis of the healthy and damaged bridge models, algorithms based on modal flexibility and modal strain energy changes before and after damage are obtained and used as the indices for the assessment of structural health state. The application of the two proposed parameters to truss-type structures is limited in the literature. The proposed multi-criteria based damage assessment procedure is therefore developed and applied to truss bridges. The application of the approach is demonstrated through numerical simulation studies of a single-span simply supported truss bridge with eight damage scenarios corresponding to different types of deck and truss damage. Results show that the proposed multi-criteria method is effective in damage assessment in this type of bridge superstructure.

• Advances in nano research
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• v.10 no.2
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• pp.175-189
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• 2021

In this article, frequency characteristics, and sensitivity analysis of a size-dependent laminated composite cylindrical nanoshell under bi-directional thermal loading using Nonlocal Strain-stress Gradient Theory (NSGT) are presented. The governing equations of the laminated composite cylindrical nanoshell in thermal environment are developed using Hamilton's principle. The thermodynamic equations of the laminated cylindrical nanoshell are obtained using First-order Shear Deformation Theory (FSDT) and Fourier-expansion based Generalized Differential Quadrature element Method (FGDQM) is implemented to solve these equations and obtain natural frequency and critical temperature of the presented model. The novelty of the current study is to consider the effects of bi-directional temperature loading and sensitivity parameter on the critical temperature and frequency characteristics of the laminated composite nanostructure. Apart from semi-numerical solution, a finite element model was presented using the finite element package to simulate the response of the laminated cylindrical shell. The results created from finite element simulation illustrates a close agreement with the semi-numerical method results. Finally, the influences of temperature difference, ply angle, length scale and nonlocal parameters on the critical temperature, sensitivity, and frequency of the laminated composite nanostructure are investigated, in details.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.376-385
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• 2007

Construction project is necessary element for human life to upgrade the quality and convenience. However, due to its contradictory nature to the environment preservation, environmental pollution and damage, deterioration of natural scenery, noise/vibration, water quality pollution, etc. caused in the process of construction greatly affect the environment. For the building or construction project, its possible impact on environment during construction work and after completion must be predicted at its design phase, which will result in the completion of the architecture convenient for human being with its environmental pollution reduced to minimum level. In this study, the checklist of environmental factors was suggested, which should be taken into account at its design phase in conducting the construction work. Proposed checklist was linked with the developed web-based system for the convenience of users like designer and construction manager, etc. It is expected that the checklist suggested by this study will help the designer and construction manager to continue the steady development from the environmental viewpoint during the design phase.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.6
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• pp.232-241
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• 2016

Installing a ventilator for an apartment house composed of over 100 dwelling units was mandated in 2006 to improve indoor air quality. In the case of mechanical ventilators, the air change rate is kept stable, however 68% of dwellers do not operate their ventilator because of an increased electrical bill and noise. In the case of natural ventilators, the former problems are settled, but there are concerns about cold draught and an increase of heating/cooling cost. Authors are developing a heat recovery type natural ventilator which is a natural ventilator equipped with total heat recovery element, and it is expected that those problems of mechanical ventilator and natural ventilator are resolved by this. The combined type diffuser of this study is an under developed fit to the heat recovery type natural ventilator above. There are no standards to evaluate the performance for this type of diffuser. Due to this issue this study investigated the performance of the ventilation and maintained a thermal environment for the combined type diffuser by comparing it with existing diffusers. The results revealed that the performances of the combined type of diffusers showed different features from the existing ones, and was estimated to be high enough in the performances above.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.111-118
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• 2000

Concrete cracking due to the temperature gradient across the wall, caused by the difference in temperature between cryogenic liquid natural gas stored and surrounding environment of in-ground LNG storage tank, is investigated in this study. Crack propagation of concrete LNG tank is effectively simulated by using a layered degenerated shell element. In addition, material nonlinearity is taken into consideration on the basis of the nonlinear elastic-orthotropic model. Finally, numerical analysis for a real LNG storage tank is conducted with the objective to verify the efficiency of the introduced model.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.415-423
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• 2008

Earth outer core is composed of iron mainly with some diluent elements, which account for the observed ca. 10% density deficit compared to the pure iron. Among candidates as the light diluents, hydrogen and oxygen were selected, and the thermodynamic stability of the following reaction was calculated; hematite + hydrogen $\to$ goethite + iron. At ambient conditions, Gibb's free energy of this reaction is 12.62 kJ/mol. On increasing pressure at room temperature, it decreases to zero at 0.068 GPa. This energy decreases at constant rate down to 200 GPa, which shows -208.26 kJ/mol at that pressure. From these results, this chemical reaction prefers the reduction environment forming the iron element and iron oxyhydroxide, so possible presence of iron oxyhydroxide with iron at proto-core can not be ruled out.

• Smart Structures and Systems
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• v.26 no.1
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• pp.1-10
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• 2020

Turkey is a transcontinental country located partly in Asia and partly in Europe, and hosted by diverse civilizations including Hittite, Urartu, Lydia, Phrygia, Pontius, Byzantine, Seljuk's and Ottomans. At various times, these built many historic monuments representing the most significant characteristics of their civilizations. Today, these monuments contribute enormously to the esthetic beauty of environment and important to many cities of Turkey in attracting tourism. The survival of these monuments depends on the investigation of structural behavior and implementation of needed repairing and/or strengthening applications. Hence, many countries have made deeper investigations and regulations to assess their monuments' structural behavior. This paper presents the dynamic behavior investigation of a monumental masonry mosque, the "İskenderpaşa Mosque" in Trabzon (Turkey), by performing an experimental examination with non-destructive testing. The dynamic behavior investigation was carried out by determining the dynamic characteristic called as natural frequencies, mode shapes and damping ratios. The experimental dynamic characteristics were extracted by Operational Modal Analysis (OMA). In addition, Finite Element (FE) model of masonry mosque was constructed in ANSYS software and the numerical dynamic characteristics such as natural frequencies and mode shapes were also obtained and compared to experimental ones. The paper aims at presenting the non-destructive testing procedure of a masonry mosque as well as the comparison of experimental and numerical dynamic characteristics obtained from the mosque.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.1
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• pp.54-65
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• 2003

The results of the research were as follows: The entire space of the village was based on natural formation in its initial formation stage. The traditional location conditions and environment were equipped with the possibility and conditions for the development of the village. Spatial boundaries were mostly divided by natural topography. The quantify of lots diminished in spatial structural factors, while the division of roads by hierarchy in terms of size became explicit. Alleys, as the minimum hierarchial nit, were degraded. The residence unit was focused on economic efficiency. Communal use facilities showed an external relations trend as central facilities. The land, unit residence and communal facilities approached the high hierarchial roads. The communal facilities showed relatively higher independence compared to the residence units. The spatial structural changes followed traditional life style in the initial stage of village formation; however, social elements mainly impacted on the changes. Since reform opening, economic elements were major causes of changes, while construction conditions, life style, and awareness of structures impacted upon the changes. Thus, the economic element is the major change element in the Korean Villages, even though other elements will also become diverse.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.517-522
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• 2019

In many businesses, chatbots enhance the user experience by providing the most immediate and direct feedback to user questions. The area of use of chatbots is growing. In this study, the three types of chatbot definition, command method, function, and platform are classified according to their distinct factors. In the process, the functional delimiter element is necessary for the Chatbot UX, which is a key technical element of the functional part of pattern recognition, natural language processing, semantic web, text mining, and context-aware computing. However, the limitations at this stage were also known. Based on this, we analyzed the chatbot's UX elements for Facebook, Skype, Telegram, and Google Assistant for a better user experience. Basic UI elements such as cards, quick response, command, and application of persistent menus are needed as user experience elements.

• Economic and Environmental Geology
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• v.33 no.3
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• pp.195-204
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• 2000

order to investigate physical characteristics and element concentrations of sediments, coastal bottom sediments were collected at 20 stations in the vicinity of Youngkwang Nuclear Power Plant. After air drying of samples in the laboratory. article size distribution was examined by Master sizer (X-350F), radio-activity by HPGe ${\gamma}$-spectrphotometer, and element concentrations by ICP-AES and AAS. According to particle size analysis , sediments are mainly composed of silt fraction weith 23% of sand, 65% of silt and 12% of clay on average. Most sediments are derived from muddy environment that silt dominates with the characteristics of 5.3${\varsigma}$ mean particle size, poorly sorted, very fine skewed and lepto-kurtic. Only two sediments are well sorted with sandy silt owing to wind, winnowing action, tide and current andits complex reactions. Element concentrations in the coastal bottom sediments are relatively high at finer sediment and show significant relationship with grain size. Index of geoaccumulation by heavy metals at every sampling station is classified as practically unpolluted. The radioactivities of the sediments were measured for 15 isotope elements, and 2 elements of K-40 and Cs-137 were detected in most sediments. The K-40 is the natural nuclide and the artificial nuclide of Cs-137 was thought to be derived from the fallout of past nuclear weapon test. The results of correlation coefficient between grain size and radioactivity shows that the activity of Cs-137 significantly increases in finer grain.