• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.1
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• pp.49-62
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• 2016

In this study, a solid oxide fuel cell (SOFC) system model including balance of plant (BOP) for building electric power generation is developed to study the effect of operating conditions on the system efficiency and power output. SOFC system modeled in this study consists of three heat-exchangers, an external reformer, burner, and two blowers. A detailed computational cell model including internal reforming reaction is developed for a planer SOFC stack which is operated at intermediate temperature (IT). The BOP models including an external reformer, heat-exchangers, a burner, blowers, pipes are developed to predict the gas temperature, pressure drops and flow rate at every component in the system. The SOFC stack model and BOP models are integrate to estimate the effect of operating parameters on the performance of the system. In this study, the design of experiment (DOE) is used to compare the effects of fuel flow rate, air flow rate, air temperature, current density, and recycle ratio of anode off gas on the system efficiency and power output.

• Fire Science and Engineering
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• v.18 no.2
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• pp.34-40
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• 2004

The effects of external flow excitation with various frequencies and amplitudes on the flame behavior and pollution emission characteristics from a laminar jet flame are experimentally investigated. Measurements of $NO_x$ emission indices ($EINO_x$), performed in vertical lifted flame like turbulent with various exciting amplitude at a constant resonance frequency, have been conducted. It was also conducted to investigate the effects of excited frequency at a constant exciting amplitude on $NO_x$ emissions with a various frequency ranged 0 Hz to 2 KHz. From the vertical lifted turbulent flame of the excited jet with resonance frequency by strong excitation was shown that the dependence of $NO_x$ emission could be categorized into three groups Group I of long flame length with high disturbances yielding high $NO_x$ emission, Group II of intermediate flame length and relative narrow flame volume with low disturbance yielding low $NO_x$ emission and Group III of long flame length and large flame volume with high time ＆ space disturbances behaviour yielding high $NO_x$ emission.

• Journal of Korea Water Resources Association
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• v.54 no.3
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• pp.203-215
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• 2021

In the present study, hydrologic data and topographical data from 2010 to 2019 were collected from three gauging stations placed in the watershed of Naeseong stream to determine changes and rates of changes in rainfall, water level & mean velocity, and water level & discharge, together with changes in rates of erosion and deposition at cross-sections of the river. Besides, effects of regulated and non-regulated rivers according to the presence of artificial regulation of flow rate of the river via artificial structure located at Seo stream (Yeongju si (Wolhogyo) station), the tributary free from construction of dams, were compared and analyzed. Results of analyses conducted in the present study revealed vegetational establishment and landforming due to increasing area of vegetational sandbar evolved in the flood plain (intermediate- or high- water level) by the drought sustained from 2013 to 2015. Continuous erosion of river bed was appeared because of narrowed flow area with low water level and increased velocity and tractive force on river bed.

• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.313-326
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• 2007

The purpose of this study was to prove that an intermediate resin layer (IRL) oan increase the bond strength to dentin by reducing the permeability of single-step adhesives. Flat dentin surfaces were created on buccal and lingual side of freshly extracted third molar using a low-speed diamond saw under copious water flow. Approximately 2.0 mm thick axially sectioned dentin slice was abraded with wet #600 SiC paper. Three single-step self-etch adhesives; Adper Prompt L-Pop (3M ESPE, St Paul, MN, USA), One-Up Bond F (Tokuyama Corp, Tokyo, Japan) and Xeno III (Dentsply, Konstanz, Germany) were used in this study. Each adhesive groups were again subdivided into ten groups by; whether IRL was used or not; whether adhesives were cured with light before application or IRL or not; the mode of composite application. The results of this study were as follows; 1. Bond strength of single-step adhesives increased by an additional coating of intermediate resin layer, and this increasement was statistically signigicant when self-cured composite was used (p < 0.001). 2. When using IRL, there were no difference on bond strengths regardless the curing procedure of single-step adhesives. 3. There were no significant difference on bond strengths between usage of AB2 or SM as an IRL. 4. The thickness of Hybrid layer was correlated with the acidity of adhesive used, and the nanoleakage represented by silver deposits and grains was examined within hybrid and adhesive layer in most of single-step adhesives. 5. Neither thickness of hybrid layer nor nanoleakage were related to bond strength.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.649-660
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• 2022

In 1959, Satomura used spectral Doppler ultrasound to express the velocity of red blood cells according to time change, and Kato defined a zero-base line that could tell the direction of blood flow, making it possible to know the direction of blood flow. This became the basis for the widely used classifications of Triphasic, Biphasic, and Monophasic. However, the above classification has limitations that confuse users with the meaning and timing of use in a clinical environment. As a result, the American Society for Vascular Medicine (SVM) and the Society for Vascular Ultrasound (SVU) A consensus document on Doppler waveform analysis was declared by the joint committee. This study tried to review this consensus and to suggest nomenclature and modifiers that can be used in the domestic vascular ultrasound clinical field. The joint committee formed by SVM and SVU recommended that the use of the triphasic waveform and the biphasic waveform be used as a multiphasic waveform rather than being used due to the ambiguity of interpretation. In addition, it was agreed to name the hybrid-type waveform, which is a monophasic and high-resistance waveform, which has always been a problem of interpretation in a clinical environment, as an intermediate resistive waveform. In addition, in order to increase the communication efficiency between the interpreter and the sonographer, waveform analysis was classified into a main descriptor and a modifier, and it was recommended to use a single nomenclature by unifying various synonyms. It is expected that this literature review will provide accurate arterial spectral Doppler waveform interpretation and an agreed-upon nomenclature to radiologists performing vascular ultrasound examination in clinical practice, and will be utilized as basic data that can contribute to the improvement of public health.

• 한국노년학
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• v.30 no.4
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• pp.1163-1177
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• 2010

This study was conducted to establish the appropriate facilities criteria of the Korean welfare devices center. We e-mail surveyed 194 welfare devices centers and analysed 13 blueprints of them. We established the following proper principles of facilities. First, consist type and area of room should depend on the type of welfare devices centers. Second, The flow of human and welfare devices should be simple. Third, the area calculated on the base of intent of center owner and the size of beds, wheelchairs, etc. Fourth, exhibit room facing with roadside may obtain advertising effect. Fifth, the storage and disinfecting room should use different entrance, and avoid the intersection of flow to prevent cross-contamination. Sixth, the access road to the exhibition and consulting room should be able to approach by the wheelchair. seventh, office room should be invisible to keep customer's privacy. Direct Cleaning-disinfecting type center on the premise that the maximum 165m², middle 150m², intermediate 140m², display at least Consultation, Cleaning-disinfecting room, storage (clean, contaminated), the office, equipped with a parking space. Entrust Cleaning-disinfecting type center on the premise that a maximum 134m², middle 119m², intermediate 109m² exhibited minimal activity room, consultation room, office, equipped with a parking space, collecting welfare when importing equipment warehouse (clean, pollution) have been proposed to equip up to.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.237-245
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• 1997

In this paper, a flow control mechanism is proposed which is based on the priority control between communication path of a node. In this scheme, demanding length of a data queue for any pre-defined, then each node in that path is forced to maintains buffer size under the limit by controlling priority level of the path. The communication path which requires higher bandwidth sets its demanding queue length smaller. By providing relationship between the priority of a path and length of its queue, the high bandwidth requesting path has a better chance to get high bandwidth by defining the smaller demanding queue size. And also, by forcing a path which has high flow rate to maintain small queue size in the path of the communication, the scheme keep the transmission delay of the path small. The size of the demanding queue of a path is regularly adjusted to meet the applications requirement, and the load status of the network during the life time of the communication. The priority control based on the demanding queue size is also provided in the intermediate nodes as well as the end nodes. By that the flow control can provide a quicker result than end to-end flow control, it provides better performance advantage especially for the high speed network.

• Journal of Korea Water Resources Association
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• v.45 no.4
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• pp.349-360
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• 2012

A horizontally curvilinear non-hydrostatic free surface model that was applicable to three-dimensional viscous flows was developed. The proposed model employed a top-layer equation to close kinematic free-surface boundary condition, and an isotropic k-${\varepsilon}$ model to close turbulence viscosity in the Reynolds averaged Navier-Stokes equation. The model solved the governing equations with a fractional step method, which solved intermediate velocities in the advection-diffusion step, and corrects these provisional velocities by accounting for source terms including pressure gradient and gravity acceleration. Numerical applications were implemented to the wind-driven currents in a two-dimensional closed basin, the flow in a steep-sided trench, and the flow in a strongly-curved channel accounting for secondary current by the centrifugal force. Through the numerical simulations, the model showed its capability that were in good agreement with experimental data with respect to free surface elevation, velocity, and turbulence characteristics.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.99-109
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• 1999

In the case of domestic general waste landfills, cumulated leachate level is often formed in the landfill due to the waste of high moisture content and it becomes important to characterize the hydraulic properties of the disposed waste. Although many hydrologic studies have been peformed for leachate barriers and pheriperal subsurface environments, few studies have been done to investigate the hydraulic property of the disposed waste and cover soils and to analyse the leachate flow behavior within landfills. In this paper, the geotechnical properties of the waste and buried cover soils are identified through the field experiment including pumping and slug tests. The results of various tests show that the field density of the cover soils is somewhat higher than the maximum laboratory density of cover soils and the vertical flow of leachate and gas in the landfill is prevented by the buried cover soils. The hydraulic conductivities of field pumping test and slug tests are well matched and stayed in the range of hydraulic conductivities of well compacted wastes in the literature.