• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.331-340
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• 2008

This study is to suggest the details of new concept of bridge deck. Experimental studies on the behavior of a inverted T-shaped steelconcrete composite deck were carried out. The part of inverted T-shaped steel is embedded in concrete. Reinforced concrete deck specimen and composite deck specimens were fabricated and static bending fracture tests were conducted. The ultimate strength and fracture strength of specimens were evaluated. The effects of shear hole crossing bars of composite deck were also analyzed. From the results of experiments, composite deck with shear hole crossing bar increased shear strength, and showed typical tensile failure. Ultimate strength and fracture strength of composite deck with shear hole crossing bar are higher than those of reinforced concrete deck. The displacement of composite deck is higher than that of reinforced concrete deck.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.237-246
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• 2006

In order to evaluate the seismic performance of damaged reinforced concrete members, particularly bridge piers, an inelastic time-dependent element is proposed. The proposed element enables increased characteristics due to structural intervention(i.e., repair or retrofitting) to be accurately reflected to the degraded strength and stiffness of the members. The inelastic time-dependent element having both birth and death time can freely be activated within the user-defined time intervals during static and dynamic time-history analysis. Comparative studies are carried out for reinforced concrete bridge piers that are repaired and retrofitted. Analytical predictions using the developed element show reasonable correlation with experimental results. Also conducted is a nonlinear time-history analysis of a reinforced concrete bridge under multiple earthquakes. The comparative analytical results prove the validation of current development. In all, it is concluded that the present element is capable of providing salient features for the healthy evaluation of seismic performance and hence seismic stability assessment of RC bridge piers being repaired and retrofitted.

• Journal of Korea Entertainment Industry Association
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• v.13 no.7
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• pp.431-440
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• 2019

This study was purposed to examine the effect of parents' overprotection on students' depression by moderating their avoidance coping. It was conducted self-reporting survey of 230 students from provincial universities. The measuring tools used in this study were PBI(The Parental Bonding Instrument), CES-D(The Center for Epidemiologic Studies-Depression Scale), Avoidance coping Style Scale. We used the analysis method SPSS 21.0 to calculate frequency, percentage and internal consistency reliability. To verify this research, we executed a correlation analysis and a hierarchical mid-term analysis. The results of the study are as follows. First, parents' overprotection, depression and avoidance coping all have a static correlation. Second, it has been confirmed that avoidance coping is a moderating variable in relations between parents' overprotection and depression. Study limitations and suggestions for further research are discussed.

• Steel and Composite Structures
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• v.44 no.4
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• pp.451-471
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• 2022

In the present paper, the static bending and buckling responses of functionally graded carbon nanotubes-reinforced composite (FG-CNTRC) beam under various boundary conditions are investigated within the framework of higher shear deformation theory. The significant feature of the proposed theory is that it provides an accurate parabolic distribution of transverse shear stress through the thickness satisfying the traction-free boundary conditions needless of any shear correction factor. Uniform (UD) and four graded distributions of CNTs which are FG-O, FG-X, FG- and FG-V are selected here for the analysis. The effective material properties of FG-CNTRC beams are estimated according to the rule of mixture. To model the FG-CNTRC beam realistically, an efficient Hermite-Lagrangian finite element formulation is successfully developed. The accuracy and efficiency of the present model are demonstrated by comparison with published benchmark results. Moreover, comprehensive numerical results are presented and discussed in detail to investigate the effects of CNTs volume fraction, distribution patterns of CNTs, boundary conditions, and length-to-thickness ratio on the bending and buckling responses of FG-CNTRC beam. Several new referential results are also reported for the first time which will serve as a benchmark for future studies in a similar direction. It is concluded that the FG-X-CNTRC beam is the strongest beam that carries the lowest central deflection and is followed by the UD, V, Λ, and FG-O-CNTRC beam. Besides, the critical buckling load belonging to the FG-X-CNTRC beam is the highest, followed by UD and FG-O.

• International Area Studies Review
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• v.15 no.1
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• pp.107-133
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• 2011

This paper aims to analyze the causal relationships between agricultural exports and economic growth in the U.S. economy by 50 states. Using the annual data from 1973 to 2007, the theoretical methodologies based on the export-led growth (ELG) model under the static model, the impulse response function (IRF) and forecast error variation decomposition (FEVD) under the vector autoregressive (VAR) model, and the Granger causality test. The results show the causal relationship between agricultural exports and economic growth at the states' level. Especially, the ELG hypothesis is strongly supported in the case of 16 states (HI, ID, KS, MD, MI, MN, NJ, NC, ND, OK, OR, RI, SD, TX, WA, and WI) and is also weakly supported in the case of 31 states. Therefore, the agricultural exports are important factor of developing in the U.S. economy, and furthermore some states (located in coastal area and breadbasket) indicate the strong evidence for agricultural exports-led growth.

• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.1-11
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• 2024

This article introduces a novel analytical model for examining the impact of porosity on shear correction factors (SCFs) in functionally graded porous beams (FGPB). The study employs uneven and logarithmic-uneven modified porosity-dependent power-law functions, which are distributed throughout the thickness of the FGP beams. Additionally, a modified exponential-power law function is used to estimate the effective mechanical properties of functionally graded porous beams. The correction factor plays a crucial role in this analysis as it appears as a coefficient in the expression for the transverse shear stress resultant. It compensatesfor the assumption that the shear strain is uniform across the depth of the cross-section. By applying the energy equivalence principle, a general expression for static SCFs in FGPBs is derived. The resulting expression aligns with the findings obtained from Reissner's analysis, particularly when transitioning from the two-dimensional case (plate) to the one-dimensional case (beam). The article presents a convenient algebraic form of the solution and provides new case studies to demonstrate the practicality of the proposed formulation. Numerical results are also presented to illustrate the influence of porosity distribution on SCFs for different types of FGPBs. Furthermore, the article validates the numerical consistency of the mechanical property changesin FG beams without porosity and the SCF by comparing them with available results.

• Steel and Composite Structures
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• v.51 no.1
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• pp.25-41
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• 2024

The measurement of pile bearing capacity is crucial for the design of pile foundations, where in-situ tests could be costly and time needed. The primary objective of this research was to investigate the potential use of fuzzy-based techniques to anticipate the maximum weight that concrete driven piles might bear. Despite the existence of several suggested designs, there is a scarcity of specialized studies on the exploration of adaptive neuro-fuzzy inference systems (ANFIS) for the estimation of pile bearing capacity. This paper presents the introduction and validation of a novel technique that integrates the fire hawk optimizer (FHO) and equilibrium optimizer (EO) with the ANFIS, referred to as ANFIS_FHO and ANFIS_EO, respectively. A comprehensive compilation of 472 static load test results for driven piles was located within the database. The recommended framework was built, validated, and tested using the training set (70%), validation set (15%), and testing set (15%) of the dataset, accordingly. Moreover, the sensitivity analysis is performed in order to determine the impact of each input on the output. The results show that ANFIS_FHO and ANFIS_EO both have amazing potential for precisely calculating pile bearing capacity. The R² values obtained for ANFIS_FHO were 0.9817, 0.9753, and 0.9823 for the training, validating, and testing phases. The findings of the examination of uncertainty showed that the ANFIS_FHO system had less uncertainty than the ANFIS_EO model. The research found that the ANFIS_FHO model provides a more satisfactory estimation of the bearing capacity of concrete driven piles when considering various performance evaluations and comparing it with existing literature.

• Tribology and Lubricants
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• v.40 no.2
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• pp.47-53
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• 2024

Surface topography plays a decisive role in determining the performance of several precision components. In particular, the surface roughness of semiconductor devices affects the precision of the circuit. In this regard, the surface topography of a given surface needs to be appropriately assessed. Typically, the average roughness is used as one of the main indicators of surface finish quality because it is influenced by both dynamic and static parameters. Owing to the increasing demand for such accurate and reliable surface measurement systems, studies are continuously being conducted to understand the parameters of surface roughness and measure the average roughness with high reliability. However, the differences in the measurement methods of surface roughness are not clearly understood. Hence, in this study, the surface roughness of the back of a silicon wafer was measured using both contact and noncontact methods. Subsequently, a comparative analysis was conducted according to various surface roughness parameters to identify the differences in surface roughness depending on the measurement method. When using a 3D laser confocal microscope, even smaller surface asperities can be measured compared with the use of a 3D profiler. The results are expected to improve the understanding of the surface roughness characteristics of precision components and be used as a useful guideline for selecting the measurement method for surface topography assessment.

• Information Systems Review
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• v.20 no.4
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• pp.25-41
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• 2018

Applying predictive analytics to enterprise processes is an effective way to reduce operation costs and enhance productivity. Accordingly, the ability to predict business processes and performance indicators are regarded as a core capability. Recently, several works have predicted processes using deep learning in the form of recurrent neural networks (RNN). In particular, the approach of predicting the next step of activity using static or dynamic RNN has excellent results. However, few studies have given attention to applying deep learning in the form of dynamic RNN to predictions of process performance indicators. To fill this knowledge gap, the study developed an approach to using process mining and dynamic RNN. By utilizing actual data from a large domestic company, it has applied the suggested approach in estimating timely stocking in purchasing process, which is an important indicator of the process. The analytic methods and results of this study were presented and some implications and limitations are also discussed.

• The Journal of the Acoustical Society of Korea
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• v.43 no.3
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• pp.305-313
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• 2024

For effective bi-static sonar operation, detection performance analysis must be performed reflecting the characteristics of sound propagation due to the ocean environment and target information. However, previous studies analyzing bistatic sonar detection performance have either not considered the ocean environment and target characteristics or have been conducted using simplified approaches. Therefore, in this study, we compared and analyzed the bistatic detection performance in Yellow sea and Ulleung basin both with and without considering target characteristics. A numerical analysis model was used to derive an accurate bistatic target strength for the submarine-shaped target, and signal excess was calculated by reflecting the simulated target strength. As a result, significant changes in detection performance were observed depending on the source and receiver locations as well as the target strength.