• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1059-1070
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• 2020

River cross-section measurement data is one of the most important input data in research related to hydraulic and hydrological modeling, such as flow calculation and flood forecasting warning methods for river management. However, the acquisition of accurate and continuous cross-section data of rivers leading to irregular geometric structure has significant limitations in terms of time and cost. In this regard, a primary objective of this study is to develop a methodology that is able to measure the spatial distribution of continuous river characteristics by minimizing the input of time, cost, and manpower. Therefore, in this study, we tried to examine the possibility and accuracy of continuous cross-section estimation by estimating the water depth for each cross-section through multiple linear regression analysis using RGB-based aerial images and actual data. As a result of comparing with the actual data, it was confirmed that the depth can be accurately estimated within about 2 m of water depth, which can capture spatially heterogeneous relationships, and this is expected to contribute to accurate and continuous river cross-section acquisition.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.3
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• pp.86-91
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• 2024

In this study, the characteristics of mortar using carbondioxide conversion capture materials (CCMs), fabricated by reacting CO₂ with desulfurization gypsum (DG) by-produced from a oil refinery, as a cement mixture. Based on the chemical component and particle size analysis results, it estimated that desulfurized gypsum reacted with carbon dioxide to produce carbonate crystals such as CaCO₃. Using CCMs as a cement mixture, physical property and durability analysis were conducted by measuring such as workability, compressive strength, compressive strength ratio after freezing-thawing and accelerated carbonation depth. The experimental results showed that as the content of the admixture increased, workability and compressive strength characteristics decreased. Compressive strength after freezing-thawing and accelerated carbonation depth also showed similar characteristics to the physical property measurement results. In addition, compared to desulfurized gypsum, using CCMs showed better physical properties and durability. This was assumed to be due to differences in the crystal phases of the mixed materials such as free-CaO and CaCO₃.

• Journal of Korea Water Resources Association
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• v.53 no.11
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• pp.951-960
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• 2020

This study investigates the adjustment processes of the rivers after weir removal through laboratory experiments. Delta upstream eroded rapidly by flow at the initial stage of the experiments and the knickpoint migrates upward. Moreover, the knickpoint moves fast upward on the condition of alternate bars. The head cutting in the bed is developed fast at the initial stage. However, the erosion speed in the bed decreases with time. The well developed alternate bars migrates with keeping their shape downstream, and the bars affect the channel downstream to adjust new environments after weir removal. Maximum scouring depth downstream and the migration speed decrease over time after removing the weir. The scouring depth in the channel without alternate bars migrates with speed. However, the depth in the channel with alternate bars migrates slow downstream. The channel with alternate bars, in turn, is adjusted well to the new equilibrium states. The maximum scouring depth migrates downstream with time, and the scouring depth and its migration speed decreases with time. The dimensionless maximum scouring depth decreases with the migration speed of dimensionless maximum scouring depth because the deeply scoured places capture the sediments from upstream and the migration speed is slow as the places are filled with them. The dimensionless maximum scouring depth is shallow as the dimensionless backfilling speed is high. The dimensionless maximum scouring depth decreases rapidly less than 5 of dimensionless backfilling speed. However, the depth decreases slow more than 5 of it.

• Progress in Medical Physics
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• v.18 no.2
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• pp.87-92
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• 2007

A thermal neutron beam facility utilizing a typical tangential beam port for Neutron Capture Therapy was installed at the HANARO, 30 MW multi-purpose research reactor. Mixed beams with different physical characteristics and relative biological effectiveness would be emitted from the BNCT irradiation facility, so a quantitative analysis of each component of the mixed beams should be performed to determine the accurate delivered dose. Thus, various techniques were applied including the use of activation foils, TLDs and ionization chambers. All the dose measurements were perform ed with the water phantom filled with distilled water. The results of the measurement were compared with MCNP4B calculation. The thermal neutron fluxes were $1.02E9n/cm^2{\cdot}s\;and\;6.07E8n/cm^2{\cdot}s$ at 10 and 20 mm depth respectively, and the fast neutron dose rate was insignificant as 0.11 Gy/hr at 10 mm depth in water The gamma-ray dose rate was 5.10 Gy/hr at 20 mm depth in water Good agreement within 5%, has been obtained between the measured dose and the calculated dose using MCNP for neutron and gamma component and discrepancy with 14% for fast neutron flux Considering the difficulty of neutron detection, the current study support the reliability of these results and confirmed the suitability of the thermal neutron beam as a dosimetric data for BNCT clinical trials.

• Smart Media Journal
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• v.1 no.1
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• pp.10-16
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• 2012

Stereo and multi-view cameras have been used to capture the three-dimensional (3D) scene for 3D contents generation. Besides, depth sensors are frequently used to obtain 3D information of the captured scene in real time. In order to generate 3D contents from captured images, we need several preprocessing operations to reduce noises and distortions in the images. 3D contents are considered as the basic media for realistic broadcasting that provides photo-realistic and immersive feeling to users. In this paper, we show technical trends of 3D image capturing and contents generation, and explain some core techniques for 3D image processing for realistic 3DTV broadcasting.

• The KSFM Journal of Fluid Machinery
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• v.2 no.4 s.5
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• pp.40-47
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• 1999

A hot water layer (HWL hereinafter) was installed at the depth of 1.2 m from the pool surface to reduce the radiation level at the pool top. After the HWL system was improved by the replacement of the filter with the Ion Exchanger to capture the Na-24, to purify the pool water of HWL and finally to reduce the radiation at the pool top. It was confirmed by the performance test of the pump and the measurement of the pressure difference through the Ion Exchanger and the strainer, that the flow characteristics of HWL system was not adversely affected after the system modification. Also the flow analysis using the pressure loss coefficients of the Ion Exchanger and strainer, calculated by the Darcy formula, could predict the flow variations by pressure changes within $10\%$ error in comparison with the field test results. It was also confirmed that HWL was maintained with the depth of 1.2 m from the pool surface because each electric water heater was electrically and thermodynamically maintained at 30 kW and the temperature of HWL was maintained with $5^{\circ}C$ higher temperature than that of pool water. Finally, it was confirmed that the pool top radiation was saturated and stabilized below 10000 nG/hr within 24 hours as the ion exchanger captured the main nucleus, Na-24 and purified the pool water of HWL.

• Agricultural and Biosystems Engineering
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• v.5 no.1
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• pp.10-20
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• 2004

Precision agriculture aims to minimize costs and environmental damage caused by agriculture and to maximize crop yield and profitability, based on information collected at within-field locations. In this process, quantification of soil physical properties, including soil strength, would be useful. To quantify and manage variability in soil strength, there is need for a strength sensor that can take measurements continuously while traveling across the field. In this paper, preliminary analyses were conducted using two datasets available with current technology, (1) cone penetrometer readings collected at different compaction levels and for different soil textures and (2) tillage draft (TD) collected from an entire field. The objective was to provide information useful for design of an on-the-go soil strength profile sensor and for interpretation of sensor test results. Analysis of cone index (CI) profiles led to the selection of a 0.5-m design sensing depth, 10-MPa maximum expected soil strength, and 0.1-MPa sensing resolution. Compaction level, depth, texture, and water content of the soil all affected CI. The effects of these interacting factors on data obtained with the soil strength sensor should be investigated through experiments. Spatial analyses of CI and TD indicated that the on-the-go soil strength sensor should acquire high spatial-resolution, high-frequency ($\ge$ 4 Hz) measurements to capture within-field spatial variability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.2037-2042
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• 2012

Synthetic aperture integral imaging is one of promising 3D imaging techniques to capture the high-resolution elemental images using multiple cameras. In this paper, we propose a method of displaying 3D images in space using the synthetic aperture integral imaging technique. Since the elemental images captured from SAII cannot be directly used to display 3D images in an integral imaging display system, we first extract the depth map from elemental images and then transform them to novel elemental images for 3D image display. The newly generated elemental images are displayed on a display panel to generate 3D images in space. To show the usefulness of the proposed method, we carry out the preliminary experiments using a 3D toy object and present the experimental results.

• Computers and Concrete
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• v.3 no.1
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• pp.65-77
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• 2006

This study reports the details of the finite element analysis of eleven shear critical partially prestressed concrete T-beams having steel fibers over partial or full depth. Prestressed concrete T-beams having a shear span to depth ratio of 2.65 and 1.59 and failing in the shear have been analyzed using 'ANSYS'. The 'ANSYS' model accounts for the nonlinear phenomenon, such as, bond-slip of longitudinal reinforcements, post-cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of the concrete and load sustenance through the bridging of steel fibers at crack interface. The concrete is modeled using 'SOLID65'-eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The reinforcements such as deformed bars, prestressing wires and steel fibers have been modeled discretely using 'LINK8' - 3D spar element. The slip between the reinforcement (rebar, fibers) and the concrete has been modeled using a 'COMBIN39'-non-linear spring element connecting the nodes of the 'LINK8' element representing the reinforcement and nodes of the 'SOLID65' elements representing the concrete. The 'ANSYS' model correctly predicted the diagonal tension failure and shear compression failure of prestressed concrete beams observed in the experiment. The capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in prestressed concrete beam has been illustrated.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.265-268
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• 2006

The preliminary design of a deep-sea injection system for carbon dioxide ocean sequestration is performed. Common functional requirements for a deep-sea injection system of mid-depth type and lake type are determined, Liquid transport system, liquid storage system and liquid injection system are conceptually determined for the functional requirements. For liquid injection system, the control of flow rate and temperature of liquid $CO_2$ in the injection pipe is needed in the view of internal flow. The function of depressing VIV(Vortex Induced Vibration) is also required in the view of dynamic stability of the injection pipe. A case study is performed for $CO_2$ sequestration capacity of 10 million tons per year. In this study, the total number of injection ships, the flow rate of liquid $CO_2$ and the configuration of a injection pipe are designed. The static structural analysis of the injection pipe is also performed. Finally the preliminary design of a deep-sea injection system is proposed.