• Korean Journal of Materials Research
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• v.19 no.7
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• pp.382-385
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• 2009

Efforts to reduce noise in industrial application fields, such as automobiles, aircrafts, and plants have been gaining considerable attention while a sound proof wall to protect people from the noise has been intensively investigated by many researchers. In this study, our research group suggested creating a new sound proof wall composed of scrap aluminum chips and perforated plates in a commercial polyester sound proof wall, which was then successfully fabricated. This wall's sound absorption characteristics were measured by an impedance tube method. The sound absorption property was evaluated by measuring the Noise Reduction Coefficient (NRC) to the standard, ASTM C 423-90a. The noise reduction coefficient of the sound proof wall composed of 3.5 vol.% and 7.5 vol.% of scrap aluminum chips relatively increased to 5% and 8% compared to the commercial polyester sound proof wall. The scrap aluminum perforated plate also relatively increased to 13% compared to the commercial polyester sound proof wall.

• Korean Journal of Food Science and Technology
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• v.16 no.3
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• pp.273-278
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• 1984

Changes in rheological properties of rice starch-water systems during the gelatinization were evaluated with the tube viscometer at temperatures between 50 and $85^{\circ}C$ and for the concentrations ranging from 3-5% rice starch. The flow consistency index increased exponentially with time at a particular temperature while being linearly dependent upon the concentration. The gelatinization rate measured by rheological method followed Arrhenius type equation. The value of activation energy of gelatinization for 5% rice starch was about 25 kcal/g mol.

• Wind and Structures
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• v.32 no.5
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• pp.405-421
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• 2021

To gain insight into the wind-induced safety concerns associated with attached tower cranes during the construction of super-tall buildings, a 606 m level frame-core tube super-tall building is selected to investigate the wind-induced vibration response and fragility of an outer-attached tower crane at all stages of construction. The wind velocity time history samples are artificially generated and used to perform dynamic response analyses of the crane to observe the effects of wind velocity and wind direction under its working and non-working resting state. The adverse effects of the relative displacement response at different connection supports are also identified. The wind-resistant fragility curves of the crane are obtained by introducing the concept of incremental dynamic analysis. The results from the investigation indicate that a large relative displacement between the supports can substantially amplify the response of the crane at high levels. Such an effect becomes more serious when the lifting arm is perpendicular to the plane of the connection supports. The flexibility of super-tall buildings should be considered in the design of outer-attached tower cranes, especially for anchorage systems. Fragility analysis can be used to specify the maximum appropriate height of the tower crane for each performance level.

• Corrosion Science and Technology
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• v.18 no.1
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• pp.24-32
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• 2019

The effects of zinc coating and heat treatment on the corrosion resistance of aluminum alloys including A1100 and the modified A3003, used as heat exchanger tube were investigated in this study. The grain size of the heat-treated specimen is larger than that of the specimen without heat treatment, but the grain size did not significantly affect the corrosion behavior. The concentration of zinc was noted at 11.3 ~ 31.4 at.% for the as-received Zn-coated samples and reduced to 1.2 ~ 2.4 at.% after the heat treatment, as measured by the scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS) on the surface. The concentration of oxygen is 22 ~ 46 at.% for the zinc coated specimens while noted at 7.4 ~ 12.8 at.% for the specimens after the removal of the coating. The corrosion behavior depended largely on the concentrations of zinc, aluminum, and oxygen on the specimen surface, but not on the Mo content. The corrosion potential was high and the corrosion rate was low for a specimen with a low zinc content, a high aluminum content, and a high oxygen content.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.2
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• pp.68-73
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• 2019

${\alpha}$-titanium alloy has a relatively low heat treatment characteristic and it is mainly subjected to heat treatment for residual stress, recovery or dynamic recrystallization. In this study, commercially pure titanium hollow castings was fabricated by gravity casting. Heat treatments were carried out at $750^{\circ}C$, $850^{\circ}C$ and $950^{\circ}C$ to investigate the effect of post-heat treatment on microstructure and mechanical properties. Beta-transus temperature ($T_{\beta}$) was about $913^{\circ}C$, and equiaxed microstructure was shown at temperature below $T_{\beta}$ and lath-type microstructure at temperature above $T_{\beta}$. Microstructure and mechanical properties did not show any significant difference in the direction of solidification for titanium hollow billet, so it can be seen that it was a well-made material for extrusion process. The optimum heat treatment condition of hollow billet castings for the seamless tube production was $850^{\circ}C$, 4 hr, FC, indicating a combination of equiaxed microstructure and appropriate mechanical properties.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.1
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• pp.27-32
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• 2022

Microbubble technology has been widely applied in various industrial fields. Recently, research on many types of microbubble application technology has been conducted experimentally, but there is a limit in deriving the optimal design and operating conditions. Therefore, if the computational fluid dynamics (CFD) analysis of multiphase flow is used to supplement these experimental studies, it is expected that the time and cost required for prototype production and evaluation tests will be minimized and optimal results will be derived. However, few studies have been conducted on multiphase flow CFD analysis to interpret fluid flow in microbubble generators using swirl flow. In this study, CFD simulation of multiphase flow was performed to analyze the air-water mixing process and fluid flow characteristics in a microbubble generator with a dual-chamber structure. Based on the simulation results, it was confirmed that a negative pressure was formed on the central axis of rotation due to the strong swirling flow. And it could be seen that the air inside the suction tube was introduced into the inner chamber of the microbubble generator. In addition, as the high-speed mixed fluid collided with external water sucked by the negative pressure near the outlet, a large amount of microbubbles was ejected due to the shear force between the two flows flowing in opposite directions.

• Advances in nano research
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• v.12 no.1
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• pp.101-115
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• 2022

Some researchers pointed out that the nonlocal cantilever models do not predict the dynamic softening behavior for nanostructures (including nanobeams) with clamped-free (CF) ends. In contrast, some indicate that the nonlocal cantilever models can capture the stiffness softening characteristics. There are substantial differences on this issue between them. The vibration analysis of porosity-dependent functionally graded nanoscale tubes with variable boundary conditions is investigated in this study. Using a modified power-law model, the tube's porosity-dependent material coefficients are graded in the radial direction. The theory of nonlocal strain gradients is used. Hamilton's principle is used to derive the size-dependent governing equations for simply-supported (S), clamped (C) and clamped-simply supported (CS). Following the solution of these equations by the extended differential quadrature technique, the effect of various factors on vibration issues was investigated further. It can be shown that these factors have a considerable effect on the vibration characteristics. It also can be found that our numerical results can capture the unexpected softening phenomena for cantilever tubes.

• Journal of Distribution Science
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• v.20 no.11
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• pp.121-129
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• 2022

Purpose: Artificial intelligence is widely used, particularly in the popular neural network theory called Deep learning. The improvement of computing speed and capability expedited the progress of Deep learning applications. The application of Deep learning in education has various effects and possibilities in creating and managing educational content and services that can replace human cognitive activity. Among Deep learning, Deep fake technology is used to combine and synchronize human faces with voices. This paper will show how to develop e-Learning content videos using those technologies and open-source tools. Research design, data, and methodology: This paper proposes 4 step development process, which is presented step by step on the Google Collab environment with source codes. This technology can produce various video styles. The advantage of this technology is that the characters of the video can be extended to any historical figures, celebrities, or even movie heroes producing immersive videos. Results: Prototypes for each case are also designed, developed, presented, and shared on YouTube for each specific case development. Conclusions: The method and process of creating e-learning video contents from the image, video, and audio files using Deep fake open-source technology was successfully implemented.

• Progress in Superconductivity and Cryogenics
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• v.8 no.2
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• pp.25-28
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• 2006

The magnet system of KSTAR(korean Superconducting Tokamak Advanced Research) is consisted of 16 TF (Toroidal Field) coils and 14 PF (Poroidal Field) coils. Internal cooling CICC(Cable in Conduit Conductor) type conductor is used for both of TF and PF coil systems. The conduit material for $Nb_3Sn$ cable is Incoloy 908 and 316LN stainless-steel was used as conduit material for NbTi cable. $Nb_3Sn$ CICC is used for all TF coils and PF1-5 coils while NbTi CICC is used for PF6 and 7 coils. $Nb_3Sn$ and NbTi strands were made for KSTAR superconducting strand. They are satisfied with KSTAR superconducotr requirements. The $Nb_3Sn$ strands supplied from three companies; MELCO (Mitsubishi Electric Co.), OAS (Outokumpu Advanced Superconductor) and KAT (Kiswire Advanced Technology) were used. A special CICC jacketing system is developed for the KSTAR CICC fabrication which uses the tube-mill process consisted of forming, welding, sizing and squaring procedures. The. procedures for cabling and jacketing of CICC for TF and PF coils and their results including the geometrical specification and characteristics of strands are described.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2412-2420
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• 2024

The International Atomic Energy Agency (IAEA) mandates safeguards to ensure non-proliferation of nuclear materials. Among inspection techniques used to detect partial defects within spent nuclear fuel (SNF), gamma emission tomography (GET) has been reported to be reliable for detection of partial defects on a pin-by-pin level. Conventional GET, however, is limited by low detection efficiency due to the high density of nuclear fuel rods and self-absorption. This paper proposes a new type of GET named Spent Fuel Internal Tomography (SFIT), which can acquire sinograms at the guide tube. The proposed device consists of the housing, shielding, C-shaped collimator, reflector, and gadolinium aluminum gallium garnet (GAGG) scintillator. For accurate attenuation correction, the source-distinguishable range of the SFIT device was determined using MC simulation to the region away from the proposed device to the second layer. For enhanced inspection accuracy, a proposed specific source-discrimination algorithm was applied. With this, the SFIT device successfully distinguished all source locations. The comparison of images of the existing and proposed inspection methods showed that the proposed method, having successfully distinguished all sources, afforded a 150 % inspection accuracy improvement.