• Journal of Korea Water Resources Association
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• v.54 no.1
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• pp.49-60
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• 2021

This study presents a methodology to estimate two distinct fractal dimensions of natural river basin by using fractal tree concept. To this end, an analysis is performed on fractal features of a complete drainage network which consists of all possible drainage paths within a river basin based on the growth process of fractal tree. The growth process of fractal tree would occur only within the limited drainage paths possessing stream flow features in a river basin. In the case of small river basin, the bifurcation process of network is more sensitive to the growth step of fractal tree than the meandering process of stream segment, so that various bifurcation structures could be generated in a single network. Therefore, fractal dimension of network structure for small river basin should be estimated in the form of a range not a single figure. Furthermore, the network structures with fractal tree from this study might be more useful information than stream networks from a topographic or digital map for analysis of drainage structure on small river basin.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.420-433
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• 2020

In order to increase the stability of existing breakwater, new caissons are installed on the back or the front of existing caissons. It is very important to evaluate wave force and wave run-up according to the change of porosity among caissons and the energy loss due to separation effects. In this study, we use the eigenfunction expansion method with Darcy's law, which describes the flow of a fluid through a porous plate, to analyze the characteristics of wave on circular breakwater of double array for various porous coefficients. To verify the numerical method, the comparison between present results and Sankarbabu et al. (2008) is made. The wave force and the wave run-up acting on each dual cylindrical caisson are calculated for various parameters by considering the energy loss and the change of porosity.

• Journal of Korea Entertainment Industry Association
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• v.15 no.2
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• pp.137-148
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• 2021

This study sought for an improvement plan of the overall preventive activity of Korean Citizen-Corps-Active-In-Disaster(CAIND) by utilizing the fact that The fire-fighters, who are focusing on social disaster response works, are surveyed for their awareness of the vivid expertise to Korean CAIND. This group is defined as the assistant organization in law about disaster prevention which, the local residents willingly made to handle the situation of disaster occurrence. Since the characteristics of volunteer activities are also inherent, related issues are also reviewed at the same time to resolve any unclear arguments by disaster prevention activity characteristics of Korean Citizen Corps Active in Disaster. Through the results, the study provided three major suggestions for an improvement plan. The results of the study are as follows: First, the quota management system of Korean CAIND that considers the characteristics of rural areas should be actively supplemented. Second, the current reward system for Korean CAIND activities at large disaster sites should be surely improved. Third, the current education and training system of Korean CAIND to satisfy regional conditions should be newly established. The results of this study are largely expected to be utilized as a basic data to develop Korean CAIND in the future.

• International Journal of Computer Science & Network Security
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• v.22 no.9
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• pp.169-174
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• 2022

The purpose of the study is to research the legal nature and essence of corrupt behavior, as well as the international and national legal aspects of the fight against corruption. The article discloses the relation between the factual results of the operation of anti-corruption normative and legal acts and the goals and objectives for which they were adopted. The effectiveness of the regulatory effect and quality of anti-corruption legislation is determined by the example of the Russian Federation. The article provides an analysis of theoretical aspects of the theory and history of the formation and development of anti-corruption legislation (on the example of Russia and some other countries, as well as international legal norms) giving several practical examples from foreign legislation demonstrating the structure of the system of government bodies battling against corrupt behavior (including its latent forms). The authors suggest that there is a need for a unified conception of information and propaganda support of state anti-corruption activities. This will make it possible to inform the population that the state is actively working to prevent corruption threats and to bring perpetrators to justice, as well as contribute to citizens' trust in the state policy in this area. At the same time, it is necessary to regularly inform the citizens about the provisions of the anti-corruption legislation, explaining the importance of their observance.

• Steel and Composite Structures
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• v.43 no.1
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• pp.79-90
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• 2022

In this study, the dynamic behavior of functionally graded layered deep beams with viscoelastic core is investigated including the porosity effect. The material properties of functionally graded layers are assumed to vary continuously through thickness direction according to the power-law function. To investigate porosity effect in functionally graded layers, three different distribution models are considered. The viscoelastically cored deep beam is exposed to harmonic sinusoidal load. The composite beam is modeled based on plane stress assumption. The dynamic equations of motion of the composite beam are derived based on the Hamilton principle. Within the framework of the finite element method (FEM), 2D twelve -node plane element is exploited to discretize the space domain. The discretized finite element model is solved using the Newmark average acceleration technique. The validity of the developed procedure is demonstrated by comparing the obtained results and good agreement is detected. Parametric studies are conducted to demonstrate the applicability of the developed methodology to study and analyze the dynamic response of viscoelastically cored porous functionally graded deep beams. Effects of viscoelastic parameter, porosity parameter, graduation index on the dynamic behavior of porous functionally graded deep beams with viscoelastic core are investigated and discussed. Material damping and porosity have a significant effect on the forced vibration response under harmonic excitation force. Increasing the material viscosity parameters results in decreasing the vibrational amplitudes and increasing the vibration time period due to increasing damping effect. Obtained results are supportive for the design and manufacturing of such type of composite beam structures.

• Steel and Composite Structures
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• v.46 no.4
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• pp.471-483
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• 2023

This paper presents an analytical hyperbolic theory based on the refined shear deformation theory for mechanical stability analysis of the simply supported advanced composites plates (exponentially, sigmoidal and power-law graded) under triangular, trapezoidal and uniform uniaxial and biaxial loading. The developed model ensures the boundary condition of the zero transverse stresses at the top and bottom surfaces without using the correction factor as first order shear deformation theory. The mathematical formulation of displacement contains only four unknowns in which the transverse deflection is divided to shear and bending components. The current study includes the effect of the geometric imperfection of the material. The modeling of the micro-void presence in the structure is based on the both true and apparent density formulas in which the porosity will be dense in the mid-plane and zero in the upper and lower surfaces (free surface) according to a logarithmic function. The analytical solutions of the uniaxial and biaxial critical buckling load are determined by solving the differential equilibrium equations of the system with the help of the Navier's method. The correctness and the effectiveness of the proposed HyRPT is confirmed by comparing the results with those found in the open literature which shows the high performance of this model to predict the stability characteristics of the FG structures employed in various fields. Several parametric analyses are performed to extract the most influenced parameters on the mechanical stability of this type of advanced composites plates.

• Geomechanics and Engineering
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• v.30 no.6
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• pp.503-515
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• 2022

The permeability coefficient is an essential parameter for the study of seepage flow in fractured rock mass. This paper discusses the feasibility and application value of using readily available RQD (rock quality index) data to estimate mine water inflow and grouting quantity. Firstly, the influence of different fracture frequencies on permeability in a unit area was explored by combining numerical simulation and experiment, and the relationship between fracture frequencies and pressure and flow velocity at the monitoring point in fractured rock mass was obtained. Then, the stochastic function generation program was used to establish the flow analysis model in fractured rock mass to explore the relationship between flow velocity, pressure and analyze the universal law between fracture frequency and permeability. The concepts of fracture width and connectivity are introduced to modify the permeability calculation formula and grouting formula. Finally, based on the on-site grouting water control example, the rock mass quality index is used to estimate the mine water inflow and the grouting quantity. The results show that it is feasible to estimate the fracture frequency and then calculate the permeability coefficient by RQD. The relationship between fracture frequency and RQD is in accordance with exponential function, and the relationship between structure surface frequency and permeability is also in accordance with exponential function. The calculation results are in good agreement with the field monitoring results, which verifies the rationality of the calculation method. The relationship between the rock mass RQD index and the rock mass permeability established in this paper can be used to invert the mechanical parameters of the rock mass or to judge the permeability and safety of the rock mass by using the mechanical parameters of the rock mass, which is of great significance to the prediction of mine water inflow and the safety evaluation of water inrush disaster management.

• Journal of Navigation and Port Research
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• v.46 no.1
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• pp.26-32
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• 2022

The port is a space where maritime transport and land transport intersect and is an essential industrial infrastructure for international trade. Therefore, it has a very important function in the national economy. Although the space and the physical facilities of a port are important, it is also very important to efficiently manage and operate these port infrastructures. The government introduced the Port Authority System to strengthen the efficiency and professionalism of port management operations. Since the port authority systemis based on port autonomy, the independence and autonomy of the port authority are very important in port management and operation. Nevertheless, the Port Authority is not functioning properly because the government interferes excessively with the operations of the Port Authority. Therefore, it is suggested that the legal system should be improved to strengthen the autonomy of the Port Authority (PA). This study examines the perception of the legal system that needs to be improved to strengthen the autonomy of the Port Authority, and suggests policy measures for Port Authority workers, civil servants, port companies, and civic groups.

• Korean Journal of Construction Engineering and Management
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• v.23 no.3
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• pp.56-65
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• 2022

This study tried to identify the key success factors of ABC by identifying the influence of ABC's success factors on project performance and analyzing the moderating effect of communication. For this purpose, factors applicable to construction projects were extracted through case studies related to the success factors of ABC, an activity-based financial management technique. The survey method was conducted as an online survey method using the Delphi method. For statistical analysis, frequency analysis and factor analysis were performed with SPSS Statistic 20, and hypothesis testing was performed with SmartPLS 2.0. As a result of the analysis, it was found that linkage with quality initiatives affects not only ABC's success factors on project performance, but also communication moderation effects. It was confirmed that linkage and communication with quality initiatives are the most important key success factors for ABC's success. Based on the results of this study, it is expected that if ABC and quality management are well linked, it will be effective in improving project performance.

• Structural Engineering and Mechanics
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• v.86 no.5
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• pp.589-605
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• 2023

This paper investigates the ductility demands of steel frames equipped with self-centring fuses under near-fault earthquake motions considering multiple yielding stages. The study is commenced by verifying a trilinear self-centring hysteretic model accounting for multiple yielding stages of steel frames equipped with self-centring fuses. Then, the seismic response of single-degree-of-freedom (SDOF) systems following the validated trilinear self-centring hysteretic law is examined by a parametric study using a near-fault earthquake ground motion database composed of 200 earthquake records as input excitations. Based on a statistical investigation of more than fifty-two (52) million inelastic spectral analyses, the effect of the post-yield stiffness ratios, energy dissipation coefficient and yielding displacement ratio on the mean ductility demand of the system is examined in detail. The analysis results indicate that the increase of post-yield stiffness ratios, energy dissipation coefficient and yielding displacement ratio reduces the ductility demands of the self-centring oscillators responding in multiple yielding stages. A set of empirical expressions for quantifying the ductility demands of trilinear self-centring hysteretic oscillators are developed using nonlinear regression analysis of the analysis result database. The proposed regression model may offer a practical tool for designers to estimate the ductility demand of a low-to-medium rise self-centring steel frame equipped with self-centring fuses progressing in the ultimate stage under near-fault earthquake motions in design and evaluation.