• Smart Structures and Systems
• /
• v.30 no.6
• /
• pp.639-648
• /
• 2022

This study aims at numerically and experimentally investigating torsional guided wave mixing with weak material nonlinearity under acoustoelastic effect in tubular structures. The acoustoelastic effect on single central frequency guided wave propagation in structures has been well-established. However, the acoustoelastic on guided wave mixing has not been fully explored. This study employs a three-dimensional (3D) finite element (FE) model to simulate the effect of stress on guided wave mixing in tubular structures. The nonlinear strain energy function and theory of incremental deformation are implemented in the 3D FE model to simulate the guided wave mixing with weak material nonlinearity under acoustoelastic effect. Experiments are carried out to measure the nonlinear features, such as combinational harmonics and second harmonics in related to different levels of applied stresses. The experimental results are compared with the 3D FE simulation. The results show that the generation combinational harmonic at sum frequency provides valuable stress information for tubular structures, and also useful for damage diagnosis. The findings of this study provide physical insights into the effect of applied stresses on the combinational harmonic generation due to wave mixing. The results are important for applying the guided wave mixing for in-situ monitoring of structures, which are subjected to different levels of loadings under operational condition.

• Journal of the Korean Chemical Society
• /
• v.34 no.1
• /
• pp.37-43
• /
• 1990

An effect of the spin-orbit coupling interaction of ligand orbitals and the intermixing │3d 〉and│4p > transition metal atomic orbitals on the ground state for a 3$d^9$ system in a strong crystal field of tetragonally distorted tetrahedral symmetry that belongs to the $D_{2d}$ point group has been investigated in this work, applying the degenerate perturbation theory. An LCAO-MO analysis in terms of the known energies of the d-d transitions for the tetragonally distorted $CuCl_4^{2-}$ ion in a single crystal of$Cs_2CuCl_4$shows that the covalent mixing of Cu 3d and ligand Cl 3p orbitals decreases dramatically with increasing Cu 4p contribution. The extent of effect on the energy level splitting for the ground state by the spin-orbit coupling interaction of ligand orbitals decreases significantly in orderTEX>$\Gamma_7(E)\;\to\;\Gamma_6(E)\; >\;\Gamma_7(B_2)\;\to\;\Gamma_6(E)\; >\;\Gamma_7(B_2)\;\to\;\Gamma_7(E)$.

• Journal of Convergence for Information Technology
• /
• v.10 no.6
• /
• pp.119-127
• /
• 2020

The purpose of this study is to verify the effect on the creativity and Usability of young Children by applying design education pro young Children gramfor using 3D printer to the kindergarten field and, through the results, to prepare a realistic way to increase the utilization of 3D printer media in infant classrooms. In order to achieve this research purpose, 38 infants aged 5 from G kindergarten located in metropolitan A are divided into each experimental group and comparative group, and from August 2017 to January 2018, data were collected through 15 experiments over a period of about 6 months. As a research tool, in the Korean version of Torrance's Creativity Test, an infant shape test and a usability test scale were used, and the data processing and analysis were conducted through technical statistical methods and covariance analysis. As a result of the study, the program using 3D printer had a statistically significant effect on promoting creativity and Usability of young Children, and in particular, it had a remarkable effect on the elaboration of creativity composition. Based on these results, discussions on the existing Nuri process, which mainly aims to cultivate creative talents, the possibility of connecting 3D printers more widely and the role of teachers were made.

• Journal of Information Technology Services
• /
• v.15 no.3
• /
• pp.1-14
• /
• 2016

According to the growing importance of science and technology policy, investment in research and development (R&D) has been increased. In this context, a patent as one of outcome of firm's systematic R&D investment is the way to hold a dominant position in companies' technology competitiveness and also to protect technology right. This study attempts to find the effects of input resources and intellectual property production activity on company value. It conducted empirical analysis based on 238 KOSDAQ-listed and medium-sized firms. Using the previous research, this study configurated research variables about activity of patent production, company value, and input of resources. Through these variables, it aims to know the effect of input of resources and activity of patent production on company value. First, the result of regression analysis shows that R&D cost has the positive effect on a patent production and sales promotion cost positively affects on the registration of the trademark. Second, the output of regression analysis indicates that a patent has the positive effect on company value but a trademark has not. With regard to the input of resources, R&D cost has the influence on company value but sales promotion cost has not. This study attempts to find the effectiveness of company's intellectual property registration on its value and suggests a way that the systematic R&D investment contributes the growth of company value.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.3B
• /
• pp.3-13
• /
• 1999

The diffusion characteristics of the high temperature and salinity water discharged in Chinhae Bay under BMP(Barge-Mounted Plants) desalination processes were simulated to access environmental impact. The 3-D baroclinic flow model is formulated by integrating the basic equations with respect to each control volume and by transforming them into a finite difference form using the space-staggered grid system. With a 3-D baroclinic flow model, the tide-induced and density-induced current was computed and confirmed by comparing with observed data. From the results of numerical experiment, it is expected that the maximum diffusion lengths of the high temperature and salinity which increase $0.6^{circ}C$ and 0.2 after discharging are 1 km and 3.5km, respectively. It may be expected that the discharge has an effect on surrounding area of discharge, but not an effect on whole area of Chinhae Bay.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.3
• /
• pp.152-157
• /
• 2015

Stack effect on high-rise building have negative effect on living environment, energy and life-safety aspect. Thus, it's necessary to find the measure to reduce the stack effect. As a result of field test on a 31-story building, a circulating type stack effect reduction technology was developed, which supplies air in the low stairs and discharges air in the high stairs. To evaluate the performance of this circulating type stack effect reduction technology on building stairs, a 3D numerical analysis was carried out by using Momentum Loss Model for analyzing leakage flow between compartments in a building. Consequently, numerical analysis proved that the stack effect on building stairs was reduced by a circulating type stack effect reduction technology.

• International Journal of Internet, Broadcasting and Communication
• /
• v.13 no.2
• /
• pp.208-217
• /
• 2021

3D-CNN is one of the deep learning techniques for learning time series data. However, these three-dimensional learning can generate many parameters, requiring high performance or having a significant impact on learning speed. We will use these 3D-CNNs to learn hand gesture and find the parameters that showed the highest accuracy, and then analyze how the accuracy of 3D-CNN varies through input data changes without any structural changes in 3D-CNN. First, choose the interval of the input data. This adjusts the ratio of the stop interval to the gesture interval. Secondly, the corresponding interframe mean value is obtained by measuring and normalizing the similarity of images through interclass 2D cross correlation analysis. This experiment demonstrates that changes in input data affect learning accuracy without structural changes in 3D-CNN. In this paper, we proposed two methods for changing input data. Experimental results show that input data can affect the accuracy of the model.

• Design & Manufacturing
• /
• v.16 no.3
• /
• pp.58-65
• /
• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• Journal of the Korean Wood Science and Technology
• /
• v.52 no.3
• /
• pp.205-220
• /
• 2024

Various polylactic acid (PLA) blends were reinforced with untreated or silane-treated micro-sized cellulose fiber (MCF), successfully prepared as 3D printing filaments and then printed using a fused filament fabrication (FFF) 3D printer. In this study, we focused on developing 3D-printed MCF/PLA composites through silane treatment of MCF and investigating the effect of silane treatment on the various properties of FFF 3D-printed composites. Fourier transform infrared spectra confirmed the increase in hydrophobic properties of silane-treated MCF by showing the new absorption peaks at 1,100 cm^-1, 1,030 cm^-1, and 815 cm^-1 representing C-NH₂, Si-O-Si, and Si-CH₂ bonds, respectively. In scanning electron microscope images of silane-treated MCF filled PLA composites, the improved interfacial adhesion between MCF and PLA matrix was observed. The mechanical properties of the 3D-printed MCF/PLA composites with silane-treated MCF were improved compared to those of the 3D-printed MCF/PLA composites with untreated MCF. In particular, the highest tensile and flexural modulus values were observed for S-MCF10 (5,784.77 MPa) and S-MCF5 (2,441.67 MPa), respectively. The thermal stability of silane-treated MCF was enhanced by delaying the initial thermal decomposition temperature compared to untreated MCF. The thermal decomposition temperature difference at T₉₅ was around 26℃. This study suggests that the effect of silane treatment on the 3D-printed MCF/PLA composites is effective and promising.

• The Korean Journal of Ecology
• /
• v.21 no.5_3
• /
• pp.687-694
• /
• 1998

In this study, the occurrence and distribution of dictyostelid cellular slime molds was investigted from soils of typical forests in Mt. Nam and the effect of soil environmental factor on cellular slime molds was investigated. The fourteen species including two undescribed species were isolated as follows: Dictyostelium brefeldianum, Polysphondylium pallidum, P. violaceum, P. pseudo-candidum in Quercus mongolica-Sorbus alnifolia forests, D. purpureum, D. mucoroides var. stoloniferum, D. dimigraformum, D. brefeldiamum, P. pallidum, P. tenuissimum, P. violoceum, P. candidum, P. pseudo-candidum in Pinus densiflora forests, D. polycephahum, D. capitatum, d. brefeldianun, P. candidum in Robinia pseudo-acacia forests, D. purpureum, D. aureostipes var, aureostipes, D. polycephalum in Quercus acutissima forests, D. minutum, D. implicatum. in the site disturbed by human. The dominant species were P. pallidum, D. brefeldiamum, P. pseudo-candidum and D. dimigraformum were the undescribed species in Korea. Environmental factors such as soil pH, water content, organic content, total nitrogen and total phosphorus made a little effect on total species number, the number of clones.