• Fire Science and Engineering
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• v.15 no.2
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• pp.59-79
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• 2001

The paper proposes alternatives for fire safety in architectural planning through heat-smoke distribution related to openings so that we decrease casualty and property loss by fire and lay a great emphasis on building high-rise apartments with consideration of fire safety in Korea. An analysis program(HFA-Heat Fluid Analysis) is built to perform simultaneously numerical analysis and experimental analysis on rooms, units and buildings. In consequence, on the first, fire prevention methods are required to be set up related to openings for design rooms since the flow of heat and smoke is influenced by the type of openings in high-rise apartments. Second, the numerical analysis showed that different planning types cause to show differences in the spreading time of heat and smoke to design the units of high-rise apartments. On the third, each unit building showed different fire behavior depending on openings by numerical analysis and small scaled experiment on heat and smoke flow.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.70-79
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• 2013

The isothermal flow structure and mixing characteristics of a hybrid/dual swirl jet combustor for micro-gas turbine (MGT) were numerically investigated. Location of pilot burner, swirl angle and direction were varied as main parameters with the identical thermal load. As a result, the variations in location of pilot nozzle, swirl angle and direction resulted in the significant change in turbulent flow field near burner exit, in particular, center toroidal recirculation zone (CTRZ) as well as turbulent intensity, and thus the flame stability and emission performance might be significantly changed. With the comparison of experimental results, the case of swirl angle $45^{\circ}$ and co-swirl flow including optimum location of pilot burner were chosen in terms of the flame stability and emissions for the development of hybrid/dual swirl jet combustor.

• Journal of Aquaculture
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• v.7 no.3
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• pp.177-187
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• 1994

The objective of the present study were to evaluate nitrification characteristics and determine optimum treatment conditions of three phase fluidized bed reactor for recycling water treatment of aquaculture. When the loading rates were 2.739-0.086kg $COD/m^3/day$ and 1.575-0.128kg $NH_4\;^+-N/m^3/day$, COD and ammonia removal efficiencies were $56.3-94.7\%\;and\; 67.3­92.6\%$, respectively. The maximum removal rates of COD and ammonia were 1200mg/l/day and 488mg/l/day, respectively. Ammonia removal rates were more than $90\%$ beyond 1hr HRT. The ammoniaremoval efficiency was sensitive to the variation of media concentration and air flowrate.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.425-431
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• 2006

In connection with redevelopment of Busan North Port, there has been lots of studies and efforts for the development of superannuated North general piers into a center of marine tourism and waterfront for the citizens of Busan. Recently it has moved to the stage of execution, after several trials to find concrete solutions. On the other hand, the change of flow field and tidal exchange cuased by redevelopment is one of the important investigation subjects. This study deals with the change of flow field and water exchange after redevelopment using numerical simulation technique, based on the general data which were collected and analyzed. As a result of simulation, the speed of tidal currents are tended to decrease near the North and inner-port and increase at the main waterway. Furthermore, the tidal exchange had a tendency to be small both before and after redevelopment by about 77% in a quasi steady state, which is about 15 days after.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4718-4725
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• 2011

Intake-air flow and distribution characteristics of the 1600cc gasoline engine intake manifold have been studied using the computer simulation. Simulation has been conducted using both one-dimensional performance simulation and three-dimensional CFD software. Steady state flow simulation result of the intake manifold shows good distribution characteristics that the standard deviation of flow coefficients is below 1.0 percentage for both one- and three-dimensional simulation. Even though one-dimensional simulation result slightly overestimates compared with three-dimensional simulation result, both results show very good agreement in flow coefficient trend. Also, unsteady state simulation result shows consistent distribution characteristics with that of steady state. It is shown that unsteady state distribution characteristics might be able to be predicted through the steady state mass distribution result.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.311-316
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• 2017

기후변화는 물 관리 측면에서 많은 변화를 일으키는 것으로 보고되고 있다. 주로 강우의 패턴을 변화시키며, 가용수자원의 지역적 편중을 심화시킨다. 기후변화에 적응하며 안정적이고 균등한 용수확보를 위해서는 홍수와 가뭄을 고려한 연속적인 물 순환 해석기술이 필요하다. 강우유출분석은 강우사상에 대한 수문순환과정을 통해 유출량을 산출하는 것으로, 주로 직접유출과 중간유출이 이에 해당된다. 강우발생 이후 무강우기간에 대해서는 기저시간 이후에 발생되는 유출량의 정량적 산출이 필요하다. 기저유출은 강우 발생 시점에 급격히 발생하기보다는 선행강우에 따른 유역 내 지하수위 분포와 대수층의 특성, 하천수위에 따라 다양한 패턴으로 나타나기 때문에 지하수대의 수리학적 성분들을 반영할 수 있어야 한다. 이를 위해서는 강우유출모의 시 지표유출량 산정과 지하수유동해석을 통한 기저유출량 산정이 동시에 이루어져야 한다. 최근 국내외에서는 다양한 형태의 수문모형과 MODFLOW를 연계한 장기유출분석에 대한 연구가 활발하게 진행되고 있다. 본 연구에서 활용한 K-DRUM(K-water Distribution Runoff Model)은 K-water에서 자체 개발한 물리적 기반의 분포형 강우유출모형으로 강우유출, 유사, 기초수질항목에 대한 3차원 분석이 가능하다. 본 모형의 A층(표층)은 지표유출을 고려한 운동파법이 적용되었고, B층과 C층(중간층), D층(지하수층)은 선형저류법이 적용되었다. MODFLOW(A Modular Three-Dimensional Finite-Difference Ground Water Flow Model)는 1980년대 USGS(United State Geolog ical Survey)에서 개발된 가장 범용적으로 사용되는 지하수유동모형이며, 모듈화 된 구조를 갖고 있어 다양한 패키지 중 필요로 하는 기능을 독립적으로 모의할 수 있는 장점이 있다. 본 연구에서는 향후 기후변화에 따른 강우의 불확실성에 대비한 유역의 장기 물순환 해석을 위해 강우유출모형인 K-DRUM과 지하수유동모형인 MODFLOW를 연계하고자한다. 연계방법은 K-DRUM에서 계산된 D층으로 침루되는 양을 MODFLOW의 함양량으로 적용하고, MODFLOW에서 산출된 기저유량을 K-DRUM의 하천유출에 적용하는 것이다. 본 연구의 성과를 갈수기 유출해석에 적용하면 정확성을 크게 향상시킬 수 있을 것으로 판단된다.

• Composites Research
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• v.34 no.4
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• pp.249-256
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• 2021

In this paper, the densification of a carbon/carbon composite during a chemical vapor infiltration (CVI) process is studied using a chemo-mechanical model. The multi-physics numerical model, developed in the previous research, couples computational fluid dynamics and major chemical reactions in the reactor. The model is especially utilized to study the effect of flow behavior around the preform on the densification. Four different types of "flow-guide" structures are placed to alter the gas flow around the preform. It is shown that the flow pattern and speed around the preform can be controlled by the guide structures. The process simulations demonstrate that the average density and/or density distribution of the preform can be improved by controlling the gas flow around the perform. In this study, a full industrial-scale reactor and process parameter were used.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.1-9
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• 2007

Numerical simulation is conducted to investigate aerodynamic force generation mechanism for the "figure-of-eight" motion of Dipteran fly, Phormia-Regina. Wing trajectory is referred to experimental result, which was observed from the tethered flight under freestream condition. Numerical simulation shows that the lift is mainly generated during downstroke motion and the large amount of thrust is generated abruptly at the end of upstroke motion. In the present work, vortical structure in the wake and the pressure field around the airfoil are examined to understand the generation of lift and thrust. Consequently, the lift generation is related with the leading edge vortex which is developed by an effective angle of attack. And the thrust generation can be explained by vortex pairing in the flow field and by vortex staying in the pressure field.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.333-348
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• 2020

The present review dealt with the state-of-art on utilization of coal bottom ash in cement-based concrete and mortar. Two types of bottom ashes generated from pulverized coal combustion and circulating fluidized-bed combustion systems have been considered. The production process, chemical and physical characteristics of both ashes, and the methodology of utilization in various cement composites are summarized. The effect of bottom ash on various properties of concrete, such as workability, strength, and durability, were reviewed from the literature. In addition, the environmental and economic aspects of utilizing bottom ash in concrete are analyzed to explore the perspectives of bottom ash utilization, and through this, the future of the utilization was considered. The effect of bottom ash on the performance of concrete and mortar was greatly depended on the condition, pretreatment, and processing of the ash. Additional processing such as crushing might contribute to stimulating the utilization in this field. In particular, if economic support is possible in terms of policy, utilization rate is expected to be improved.

• Journal of the Korean Society of Visualization
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• v.20 no.3
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• pp.136-145
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• 2022

Later flow immunoassay (LFIA) is a protein analytical method based on immunoreaction. On the LFIA based protein analytical method, bioreceptor molecule plays a key role, and so a system that evaluates and manages the binding affinity of bioreceptor is needed to secure detection reliability. In this study, Lateral Flow Immunoassay based rapid Bioreceptor Screening Method (rBSM) is presented that provide a simple and quick evaluating method for the binding affinity to the target protein of the antibody as model bioreceptor. To verify this evaluation method, Virus-like particles (VLP) and anti-VLP antibodies are selected as a model norovirus, which is target protein, and the candidate bioreceptors respectively. Among the 5 different candidate antibodies, appropriate antibody could be sorted out within 30 minutes through rBSM. In addition, selected antibodies were applied to two representative LFIA based techniques, sandwich assay and competitive assay. Among these methods, sandwich assay showed more effective VLP detection method. Through applying selected antibodies and techniques to the commercialized mass production lines, an VLP detecting LFIA kit was developed with a detection limit of 10¹² copies/g of VLPs in real samples. Since this proposed method in this study could be easily transformable into other combinations with bioreceptors, it is expected that this technique would be applied to LFIA kit development system and bioreceptor quality management.