• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.361-365
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• 2005

An absolute interferometer system with multiple point-sources is devised for tile 3-D measurement of rough surface profiles. The positions of the point sources are determined to be the system parameters that influence the measurement accuracy, so they are calibrated precisely prior to performing actual measurements. For the calibration, a CCD camera composed of a two-dimensional array of photo-detectors was used. Performing optimization of the cost function constructed with phase values measured at each pixel on the CCD camera, the position coordinates of each point source is precisely determined. Measurement results after calibration performed for the warpage inspection of chip scale packages (CSPs) demonstrate that the maximum discrepancy is 9.8 mm with a standard deviation o( 1.5 mm in comparison with the test results obtained by using a Form Taly Surf instrument.

• Clinics in Orthopedic Surgery
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• v.10 no.4
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• pp.462-467
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• 2018

Background: Significant discrepancy exists between anatomical plate designs and the anatomy of the native distal radius, which may be attributable to considerable morphometric variations in the volar aspect of the distal radius. We aimed to evaluate the degree of variability in the morphometry of the distal radius and identify factors associated with this variability. Methods: We measured the volar surface angle (VSA) of the intermediate and lateral columns and the volar surface width (VSW) in the distal radius from three-dimensional computed tomography scans acquired from 81 cadaveric forearms. These morphometric parameters were compared between the lateral and intermediate columns, between males and females, and between Koreans and Caucasians. Caucasian morphometric data were obtained and pooled from the previous studies. The coefficient of variation was used to assess the variability of the parameters and Cohen's d to estimate the effect size of the difference between groups. Results: The average VSA of the lateral column was $22^{\circ}{\pm}6^{\circ}$, and that of the intermediate column was $29^{\circ}{\pm}8^{\circ}$ in Koreans (p < 0.001). The variability was high for both VSAs. The VSA of the intermediate column was significantly larger in males than in females (p < 0.001) and in Caucasians than in Koreans (p < 0.001). The average VSW of distal radius was $30{\pm}3mm$ at the watershed line, and it became narrower proximally. The VSW was significantly larger in males than in females (p < 0.001) and in Koreans than in Caucasians (p < 0.001). The effect sizes of the difference for the VSA and VSW between sexes, races and columns were medium to large. Conclusions: Considerable variability exists in the morphometry of the volar distal radius, with sex, race, and column as contributing factors. These results suggest that surgeons should carefully choose an anatomical volar locking plate with appropriate angulation characteristics for each patient to achieve patient-specific alignment of the distal radius.

• Journal of Powder Materials
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• v.25 no.6
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• pp.475-481
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• 2018

Selective laser melting (SLM), a type of additive manufacturing (AM) technology, leads a global manufacturing trend by enabling the design of geometrically complex products with topology optimization for optimized performance. Using this method, three-dimensional (3D) computer-aided design (CAD) data components can be built up directly in a layer-by-layer fashion using a high-energy laser beam for the selective melting and rapid solidification of thin layers of metallic powders. Although there are considerable expectations that this novel process will overcome many traditional manufacturing process limits, some issues still exist in applying the SLM process to diverse metallic materials, particularly regarding the formation of porosity. This is a major processing-induced phenomenon, and frequently observed in almost all SLM-processed metallic components. In this study, we investigate the mechanical anisotropy of SLM-produced 316L stainless steel based on microstructural factors and highly-oriented porosity. Tensile tests are performed to investigate the microstructure and porosity effects on mechanical anisotropy in terms of both strength and ductility.

• Advances in materials Research
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• v.8 no.2
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• pp.117-135
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• 2019

The lifetime of a gas turbine combustor is typically limited by the durability of its liner, the structure that encloses the high-temperature combustion products. The primary objective of the combustor thermal design process is to ensure that the liner temperatures do not exceed a maximum value set by material limits. Liner temperatures exceeding these limits hasten the onset of cracking which increase the frequency of unscheduled engine removals and cause the maintenance and repair costs of the engine to increase. Hot gas temperature prediction can be considered a preliminary step for combustor liner temperature prediction which can make a suitable view of combustion chamber conditions. In this study, the temperature distribution of ceramic panels for a V94.2 gas turbine combustor subjected to realistic operation conditions is presented using three-dimensional finite difference method. A simplified model of alumina ceramic is used to obtain the temperature distribution. The external thermal loads consist of convection and radiation heat transfers are considered that these loads are applied to flat segmented panel on hot side and forced convection cooling on the other side. First the temperatures of hot and cold sides of ceramic are calculated. Then, the thermal boundary conditions of all other ceramic sides are estimated by the field observations. Finally, the temperature distributions of ceramic panels for a V94.2 gas turbine combustor are computed by MATLAB software. The results show that the gas emissivity for diffusion mode is more than premix therefore the radiation heat flux and temperature will be more. The results of this work are validated by ANSYS and ABAQUS softwares. It is showed that there is a good agreement between all results.

• Composites Research
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• v.32 no.5
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• pp.206-210
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• 2019

As the use of composite materials of woven structure has expanded to various fields such as automobile and aviation industry, there has been a need for reliability problems and prediction of mechanical properties of woven composites. In this study, finite element analysis for predicting the mechanical properties of composite materials with different weaving structures was conducted to verify similarity with experimental static properties and an effective modeling method was developed. To reflect the characteristics of the weave structure, the meso-scale representative volume element (RVE) was used in modeling. Three-dimensional modeling was carried out by separating the yarn and the pure matrix. Hashin's failure criterion was used to determine whether the element was failed, and the simulation model used a progressive failure model which was suitable for the composite material. Finally, the accordance of the modeling and simulation technique was verified by successfully predicting the mechanical properties of the composite material according to the weave structure.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.19-24
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• 2019

Digital technologies in the digital image field are developing and changing rapidly while creating various forms of media environments. In particular, broadcasting image-processing technologies provide more realistic images through the development of multimedia technology. Consequently, the needs of flat image quality have been nearly met, leading to technological saturation. Currently, flat images possess the advantages of popularity and freedom from visual fatigue over three-dimensional stereoscopic images. A complementary technology for flat images is the stereoscopic perception improvement technology. To examine correlations between stereoscopic perception and colour attributes for graphic images on flat displays, we have conducted experiments related to stereoscopic perception and analysed the results. In these experiments, the colour attributes of hue, value, and chroma were applied at different levels. Next, the factors that provide the highest stereoscopic perception and their interactions were analysed through analysis of variance. Finally, this study defines the significance of colour factors related to stereoscopic perception by analysing the experimental results, and proposes a colour adjustment method for improved stereoscopic perception in graphics image processing.

• Journal of Conservation Science
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• v.37 no.4
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• pp.362-369
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• 2021

In museums, exhibition content focuses mostly on cultural heritage's historical values and functions, but doing so tends to limit visitors' interest and immersion. To counter this limitation, the study developed an experiential media art exhibition fusing bronze mirrors' traditional production technology and modern conservation science. First, for the exhibition system, scientific cultural heritage contents were projected on the three-dimensional (3D) printed bronze mirror through interactions between motion recognition digital information display (DID) and the projector. Then, a scenario of 17 missions in four stages (production process, corrosion mechanism, scientific analysis and diagnosis, and conservation treatment and restoration) was prepared according to the temporal spectrum. Additionally, various media art effects and interaction technologies were developed, so visitors could understand and become immersed in bronze mirrors' scientific content. A user test was evaluated through the living lab, reflecting generally high levels of satisfaction (90.2 points). Qualitative evaluation was generally positive, with comments such as "easy to understand and useful as the esoteric science exhibition was combined with media art" (16.7%), "wonderful and interesting" (11.7%), and "firsthand experience was good" (9.2%). By combining an esoteric science exhibition centered on principles and theories with visual media art and by developing an immersive directing method to provide high-level exhibition technology, the exhibition induced visitors' active participation. This exhibition's content can become an important platform for expanding universal museum exhibitions on archaeology, history, and art into conservation science.

• Journal of Technologic Dentistry
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• v.43 no.2
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• pp.48-55
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• 2021

Purpose: This study aimed to analyze deformation according to post-curing of complete arch artificial teeth for temporary dentures printed with a digital light processing (DLP) printer. Methods: An edentulous model was prepared and an occlusal rim was produced. The edentulous model and occlusal rim were scanned using a model scanner. A complete denture was designed using a dental computer-aided design, and the denture base and artificial tooth were separated. Ten complete arch artificial teeth were printed using a 3D printer (DLP). Complete arch artificial teeth was classified into the following three groups: a group no post-curing (NC), a group with 10 minutes post-curing (10M), and a group with 20 minutes post-curing (20M). Specimens were scanned using a model scanner. The scanned data were overlapped with the reference data. Statistical analysis was performed using one-way ANOVA analysis of variance, Kruskal-Wallis test, and Mann-Whitney U test (α=0.05). Results: Regarding the overall deviation of complete arch artificial teeth, the NC group showed the lowest mean deviation of 111.13 ㎛ and the 20M group showed the highest mean deviation of 131.03 ㎛. There were statistically significant differences among the three groups (p<0.05). Conclusion: The complete arch artificial tooth showed deformation due to post-curing. In addition, the largest shrinkage deformation was observed at 10 minutes of post-curing, whereas the least deformation was observed at 20 minutes.

• Journal of Fashion Business
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• v.25 no.1
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• pp.51-64
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• 2021

The purpose of this study was to develop smart bags that combining fashion-specific trends and smart information technologies such as light-emitting diodes(LED) and optic fibers by grafting marquage techniques that have recently become popular as part of eco-fashion. We applied e-textiles by designing leather tote bags that could show off LED luminescence. A total of two tote bags, a white-colored peacock design and a black-colored paisley design, divided the LED's light-emitting method into two types, incremental lighting and random light-emission to suit each design, and the locations of the optical fibers were also reversed depending upon the design. The production of circuits for the LEDs and optical fibers was based on the design, and a flexible conductive fabric was laser-cut instead of wire line and attached to the circuit-line location. A separate connector was underwent three-dimensional(3D)-modeling and was connected to high-luminosity LEDs and optic fiber bundles. The optical fiber logo part expressed a subtle image using a white-colored LED, which did not offset the LED's sharp luminous effects, suggesting that using LEDs with fiber optics allowed for the expression of each in harmony without being heterogeneous. Overall, the LEDs and fiber optic fabric were well-harmonized in the fashion bag using marquage techniques, and there was no sense of it being a mechanical device. Also, the circuit part was made of conductive fabric, which is an e-textile product that feels the same as a thin, flexible fabric. The study confirmed that the bag was developed as a smart wearable product that could be used in everyday life.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.399-413
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• 2020

The numerical simulation of liquid sloshing in the three-dimensional tanks under horizontal excitation and roll excitation was carried out, and the inhibition effect of different baffles on the sloshing phenomenon was investigated. The numerical calculations were carried out by the nonlinear Boundary Element Method (BEM) with Green's theorem based on the potential flow, which was conducted with the governing equation corresponding to the boundaries of each region. The validity of the method was verified by comparing with experimental values and published literatures. The horizontal baffle, the vertical baffle and the T-shaped baffle in the sloshing tanks were investigated respectively, and the baffles' position, dimension and the liquid depth were provided and discussed in detail. It is drawn that the baffle shape plays a non-negligible role in the tank sloshing. The vertical baffle is a more effective way to reduce the sloshing amplitude when the tank is under a horizontal harmonic excitation while the horizontal baffle is a more effective way when the tank is under a roll excitation. The amplitude of free surface elevation at right tank wall decreases with the increasing of the horizontal baffle length and the vertical baffle height. Although the T-shaped baffle has the best suppression effect on tank sloshing under horizontal excitation, it has limited suppression effect under roll excitation and will complicate the sloshing phenomenon when changing baffle height.