• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.285-292
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• 2012

The integrated gasification combined cycle (IGCC) system is well known for its high efficiency compared with that of other coal fueled power generation system. IGCC offers substantial advantages over pulverized coal combustion when carbon capture and storage (CCS) is required. Commercial plants employ different types of quenching system to meet the purpose of the system. Depending on that, the downstream units of IGCC can be modeled using different operating conditions and units. In case with $CO_2$ separation and capture, the gasifier product must be converted to hydrogen-rich syngas using Water Gas Shift (WGS) reaction. In most WGS processes, the water gas shift reactor is the biggest and heaviest component because the reaction is relatively slow compared to the other reactions and is inhibited at higher temperatures by thermodynamics. In this study, tehchno-econimic assessments were found according to the quench types and operating conditions in the WGS system. These results can improve the efficiency and reduce the cost of coal gasification.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.764-768
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• 2011

The process of $CO_2$ capture using aqueous Monoethanolamine(MEA) has been considered as one of the leading technologies for intermediate-term strategy to reduce the $CO_2$ emission. This MEA process, however, consumes relatively a large amount of energy in the stripper for absorbent regeneration. For this reason, various process alternatives are recently established to reduce the regeneration energy. This paper suggests a flue gas split configuration as one of MEA process alternatives and then simulates this process using commercial simulator. This flue gas splitting has an effect on reducing the temperature of the lower section of absorber as well as decreasing the absorbent flow rate. Compared to the base model, this optimized flue gas split process provides 6.4% reduction of solvent flow rate and 5.8% reduction of absorbent regeneration energy.

• Nuclear Engineering and Technology
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• v.53 no.2
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• pp.626-636
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• 2021

Boron-neutron capture therapy (BNCT) is a cancer treatment method that exploits the high neutron reactivity of boron. Monitoring the prompt gamma rays (PGs) produced during neutron irradiation is essential for ensuring the accuracy and safety of BNCT. We investigate the imaging of PGs produced by the boron-neutron capture reaction through Monte Carlo simulations of a gamma camera with a SrI₂ scintillator and parallel-hole collimator. GAGG scintillator is also used for a comparison. The simulations allow the shapes of the energy spectra, which exhibit a peak at 478 keV, to be determined along with the PG images from a boron-water phantom. It is found that increasing the size of the water phantom results in a greater number of image counts and lower contrast. Additionally, a higher septal penetration ratio results in poorer image quality, and a SrI₂ scintillator results in higher image contrast. Thus, we can simulate the BNCT process and obtain an energy spectrum with a reasonable shape, as well as suitable PG images. Both GAGG and SrI₂ crystals are suitable for PG imaging during BNCT. However, for higher imaging quality, SrI₂ and a collimator with a lower septal penetration ratio should be utilized.

• Geomechanics and Engineering
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• v.35 no.4
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• pp.449-464
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• 2023

Advanced nonlinear effective stress constitutive models are started to be frequently used in one-dimensional (1D) and two-dimensional (2D) site response analysis for assessment of porewater generation and liquefaction potential in soft soil deposits. The emphasis of this research is on the assessment of the implementation of this category of models at the element stage. Initially, the performance of a coupled porewater pressure (PWP) and constitutive models were evaluated employing a catalogue of 40 unidirectional cyclic simple shear tests with a variety of relative densities between 35% and 80% and effective vertical stresses between 40 and 80 kPa. The authors evaluated three coupled constitutive models (PDMY02, PM4SAND and PDMY03) using cyclic direct simple shear tests and for decide input parameters used in the model, procedures are recommended. The ability of the coupled model to capture dilation as strength is valuable because the studied models reasonably capture the cyclic performance noted in the experiments and should be utilized to conduct effective stress-based 1D and 2D site response analysis. Sandy soils may become softer and liquefy during earthquakes as a result of pore-water pressure (PWP) development, which may have an impact on seismic design and site response. The tested constitutive models are mathematically coupled with a cyclic strain-based PWP generation model and can capture small-strain stiffness and large-strain shear strength. Results show that there are minor discrepancies between measured and computed excess PWP ratios, indicating that the tested constitutive models provide reasonable estimations of PWP increase during cyclic shear (r_u) and the banana shape is reproduced in a proper way indicating that dilation and shear- strain behavior is well captured by the models.

• Journal of Korea Multimedia Society
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• v.16 no.8
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• pp.972-981
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• 2013

Non-linear editing is an editing method that, unlike linear editing, enables users to insert a new frame between existing frames. Non-linear editing systems are systems that support such method, and are composed of a computer, a software and a capture board that inputs/outputs video signals. Non-linear editing is used for modern television broadcasts and movie productions. Recorded footage and various graphic sources are combined into one visual content through a non-linear editing system. In this paper, we will look into functions of various non-linear editing softwares (mainly the most common of all; Adobe Premiere) as well as their merits and demerits during the editing process, and will also discuss their future Improvement direction.

• Industrial Engineering and Management Systems
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• v.14 no.1
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• pp.58-72
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• 2015

A primary concern of national R&D plans is to encourage technological development in private firms and research institutes. For effective R&D planning and program support, it is necessary to assess technological impacts that may exist both directly and indirectly among technology areas within the whole technology system; however, previous studies analyze only direct impacts among technologies, failing to capture both direct and indirect impacts. Therefore, this study proposes an approach based on decision-making trial and evaluation laboratory (DEMATEL) to identifying specific characteristics of technology areas, such as technological impact and degree of cause or effect (DCE). The method employs patent co-classification analysis to construct a technological knowledge flow matrix. Next, to capture both direct and indirect effects among technology areas, it incorporates the modified DEMATEL process into patent analysis. The method helps analysts assess the technological impact and DCE of technology areas, and observe their evolving trajectories over time, thereby identifying relevant technological implications. This study presents a case study using Korean patents registered during 2003-2012. We expect our analysis results to be helpful input for R&D planning, as well as the suggested approach to be incorporated into processes for formulating national R&D plans.

• Smart Structures and Systems
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• v.15 no.6
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• pp.1543-1567
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• 2015

In this study, a wireless crack sensor is developed for monitoring cracks propagating in two dimensions. This sensor is developed by incorporating a laser-based optical navigation sensor board (ADNS-9500) into a smart wireless platform (Imote2). To measure crack propagation, the Imote2 sends a signal to the ADNS-9500 to collect a sequence of images reflected from the concrete surface. These acquired images can be processed in the ADNS-9500 directly (the navigation mode) or sent to Imote2 for processing (the frame capture mode). The computed crack displacement can then be transmitted wirelessly to a base station. The design and the construction of this sensor are reported herein followed by some calibration tests on one prototype sensor. Test results show that the sensor can provide sub-millimeter accuracy under sinusoidal and step movement. Also, the two modes of operation offer complementary performance as the navigation mode is more accurate in tracking large amplitude and fast crack movement while the frame capture mode is more accurate for small and slow crack movement. These results illustrate the feasibility of developing such a crack sensor as well as point out directions of further research before its actual implementation.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.508-511
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• 2011

Dust released from the rotating timber cutting process causes various kinds of diseases as well as safety issues. Although there were lots of efforts to reduce the amount of dust by installing large-sized dust collectors or by using expensive high-quality cutters, they proved to be not so effective. In this study we want to modify and improve the design of the rotary cutter system to prevent dust from being released to the environment as possible by using computational fluid dynamics (CFD) analysis. We have developed CFD models of the conventional cutter and several design modifications. Through the CFD analysis the characteristics of the air flow was predicted, and then the behavior of dust produced during the cutting process was analyzed for different designs. The most efficient design feature to capture dust inside the cutter as much as possible was chosen based on the CFD analysis results. Finally the prototype of the ratary saw machine was constructed and tested to check the dust capturing efficiency, which result is reasonably consistent with the predicted performance through the CFD analysis.

• Proceedings of the KOR-KST Conference
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• 2003.02a
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• pp.127-150
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• 2003

This research presents a novel application of static traffic assignment methods, but with a variable time value, for estimating the market share of a high-speed rail (HSR) in the NW-SE corridor of Korea which is currently served by the airline (AR), conventional rail (CR), and highway (HWY) modes. The proposed model employs the time-space network structure to capture the interrelations among all competing transportation modes, and to reflect their supply- and demand-sides constraints as well as interactions through properly formulated link-node structures. The embedded cost function for each network link offers the flexibility for incorporating all associated factors, such as travel time and fare, in the model computation, and enables the use of a distribution rather than a constant to represent the time-value variation among all transportation mode users. To realistically capture the tripmakers' value-of-time (VOT) along the target area, a novel method for VOT calibration has been developed with aggregate demand information and key system performance data from the target area. Under the assumption that intercity tripmakers often have nearly "perfect" travel information, one can solve the market share of each mode after operations of HSR for each O-D pair under the time-dependent demand with state-of-the-art traffic assignment. Aside from estimating new market share, this paper also investigated the impacts of HSR on other existing transportation modes.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.257-257
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• 2015

Carbon Capture and Storage with ocean sequestration is being considered as one of the most effective option for reducing the $CO_2$ net flux from atmosphere nowadays. But it is still possible for $CO_2$ substance to leaks out from transport pipeline or from the under seabed storage sites and causing damage to ambient environment. The behavior of liquid $CO_2$ under droplet shape would be strongly affected by the presence of other contaminants such as $SO_2$ comes from processing processes. This presentation shows the behavior in the sea water of pure liquid $CO_2$ droplets as well as droplets that consist of $SO_2$ substances. The study uses computational fluid dynamic models in comparison with experimental data from other previous researchers. Droplet of liquid $CO_2$ is assumed to be released at several depths in deep ocean, with other environmental conditions are set up respectively. All calculations are conducted with many different ratio of contaminant $SO_2$ to provide fundamental data of those particles rising characteristics. The effect of contaminants on the behavior of $CO_2$ droplets would be clearly shown through the results of particle deformation, terminal rising velocity happen due to buoyancy force driving from the difference in density of $CO_2$ substance and ocean water around.