• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.529-537
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• 2021

Wind tunnel tests were carried out with a scramjet high speed vehicle. Since the scramjet engine does not have a compressor, it has a simple structure, but it is important to design the intake for the supersonic combustion in the combustion chamber. In this study, internal flow characteristics and the starting condition were analyzed by measuring the pressure at the isolator exit just before the combustion chamber, and the intake performance parameters were calculated and compared the result on every Mach number. The aerodynamic characteristics of the flow-through high speed vehicle were analyzed and internal drag correction is required to precisely analyze the aerodynamic characteristics. In this paper, an experimental technique using three probes for internal drag correction was proposed. By applying internal drag correction, it was able to figure out the effect of the internal flow on the aerodynamic force of the vehicle.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.368-377
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• 2013

The Urea-SCR system commercialized shows a remarkable performance to reduce NOx emission in heavy duty diesel engines. However, Urea-water solution injected upstream a mixer, which is set up inside a exhaust pipe to promote exhaust gas-atomized droplet mixing, bumps up against the wall of a exhaust pipe as the droplets flow downstream through the exhaust gas. The urea deposited on the wall of the exhaust pipe is changed into the Urea-salt, resulting in the decreased life-time of the SCR catalysts. Therefore, the development of the urea deposition avoidance technologies is being treated as an important issue of the Urea-SCR systems. An experimental study was carried out to investigate the effects of the wall flow characteristics around the mixer-housing assembly with the variation of the mixer housing surrounding and supporting the mixer, which is designed to increase the wall flow and then to reduce droplet deposition. The flow characteristics was investigated by using a hot-wire anemometry for 2-D simplified duct model, and the housing tilt angles and the position of the mixer were changed : angle of $0^{\circ}$, $1^{\circ}$, $2^{\circ}$, $3^{\circ}$, and mixer positions of 0L, 0.5L, 1L. The results showed that the wall flow onto the exhaust pipe was improved with changing the tilt angle of the mixer housing, and the wall flow improved more when the position of the mixer was on 1L.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.760-767
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• 2014

An experimental study is carried out to investigate the effect of jet stream in the gab of rectangular cylinders with different length in a parallel arrangement by using PIV method in a circulating water channel. The height(h) of the rectangular cylinder and the gap between the cylinder is 10mm, and the width(B) which is 300mm. The length of the model for flow direction was applied to 30mm, 60mm, 90mm & 120mm, The aspect ratio of a model on the basis of height(H=30mm) is 1, 2, 3 and 4. Reynolds number $Re=1.4{\times}10^4$, $Re=2.0{\times}10^4$, $Re=2.9{\times}10^4$ based on the height(H) of model for the distance of tidal distributions as of water depth have been applied during the whole experiments. The measurement area was set to 5H rear of the cylinder. As a result, Vortex size in the wake area were increased as velocity increased. and high aspect ratio increased through-flow velocity component in the near wake. Velocity deficit increased highly after near-wake area and low aspect ratio.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.7
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• pp.2386-2396
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• 1996

A numerical simulation has been performed for isothermal and reacting flows in an exisymmetric, bluff-body research combustor. The present formulation is based on the density-weighted averaged Navier-Stokes equations together with a k-epsilon. turbulence model and a modified eddy-breakup combustion model. The PISO algorithm is employed for solution of thel Navier-Stokes system. Comparison between measurements and predictions are made for a centerline axial velocities, location of stagnation points, strength of recirculation zone, and temperature profile. Even though the numerical simulation gives acceptable agreement with experimental data in many respects, the present model is defictient in predicting the recoveryt rate of a central near-wake region, the non-isotropic turbulence effects, and variation of turbulent Schmidt number. Several possible explanations for these discrepancies have been discussed.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.154-163
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• 2022

This paper tried to examine the implications of the sites of memory and diaspora memory of the life of Jun Itami(Yoo Dong-ryong), a Korean architect in Japan who is interpellated as Zainichi Koreana adopting theoretical and methodological discussions on memory, sites of memory, diaspora, and identity. To this end, the documentary was selected as the subject of analysis. According to the research results, which consists of a total of 48 scenes, is based on the assumption that the sea and Japan and Korea between the sea are the space of memory, and emphasizes that Itami Jun, who had to live as a borderliner and a stranger is disengaged from the borders of nationalities, territories, and countries. In particular, the story of Jun Itami set the sea as a diachronic space(sites of memory) that penetrates the past and present and explores his diaspora identity. The sites of memory of Jun Itami reconstructed in can be said to be a memory space that makes Yoo Dong-ryong more firmly aware of his diaspora identity as a Korean.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.2
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• pp.89-96
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• 2000

Slug tests are the most widely used field method for quantification of hydraulic conductivity of porous media. Well recovery is affected by well casing, borehole radii, screened length, hydraulic conductivity, and specific storage of porous media. In this study, a new slug tests model was developed through finite element approximation and the validity and usefulness of the model were tested in various ways. Water level fluctuation in a well under slug test and cons-equent groundwater flow in the surrounding porous medium were appropriately coupled through estimation of well-flux using an iteration technique. Numerical accuracy of the model was verified using the Cooper et al. (1967) solution. The model has advantages in simulations for monitored slug tests, partial penetration, and inclusion of storage factor. Volume coverage of slug tests is significantly affected by storage factor. Magnitude and speed of propagation of head changes from a well increases as storage factor becomes low. It will be beneficial to use type curves of monitored head transients in the surrounding porous formation for estimation of specific storage. As the vertical component of groundwater flow is enhanced, the influence of storage factor on well recovery decreases. For a radial-vertical flow around a partially penetrated well, deviations between hydraulic estimates by various methods and data selection of recovery curve are negligible on practical purposes, whereas the deviations are somewhat significant for a radial flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.127-138
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• 2016

Diesel vehicles should be equipped with urea-selective catalytic reduction(SCR) system as a high-performance catalyst, in order to reduce harmful nitrogen oxide emissions. In this study, a three-dimensional Eulerian-Lagrangian CFD analysis was used to numerically predict the multiphase flow characteristics of the urea-SCR system, coupled with the chemical reactions of the system's transport phenomena. Then, the numerical spray structure was modified by comparing the results with the measured values from spray visualization, such as the injection velocity, penentration length, spray radius, and sauter mean diameter. In addition, the analysis results were verified by comparison with the removal efficiency of the nitrogen oxide emissions during engine and chassis tests, resulting in accuracy of the relative error of less than 5%. Finally, a verified CFD analysis was used to calculate the interanl flow of the urea-SCR system, thereby analyzing the characteristics of pressure drop and velocity increase, and predicting the uniformity index and overdistribution positions of ammonia.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.1
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• pp.43-48
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• 1997

The present study is aimed to investigate experimentally on the hydrodynamic behaviours of air ~ pulverized coal flow in rectangular combustor with cavity. Mean velocity, density and tur¬bulent properties of pulverized coal in rectangular entrained flow combustor were measured by PDA. Experimental results show that the flow reattachment point at the lower plane in the com¬buster chamber has been developed near X/D= 15. The similarities at each section are found after the flow reattachment point. The maximum values of turbulent intensity and Reynolds shear stress have been shown near Y/D=6, which is higher than centerline. The maximum density of the pulverized coal sited in the range ofY/D=6~8.

• Journal of the Korean Society of Costume
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• v.51 no.8
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• pp.123-139
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• 2001

본고는 공간, 시간, 계급, 종교 등 하위문화 텍스트의 병행인용 즉 상호텍스트성(intertextuality)을 통해, 20세기 대중 문화의 상징 마돈나 뮤직 비디오와 공연 등의 인체, 의상, 이미지 등에 나타난 포스트모던 정체성을 연구함으로써, 현대 미디어 문화를 관통하는 주체적 여성 정체성과 미적 주관성을 이해하고자한다. 첫째, 상호공간텍스트성 복식은 스패니쉬룩. 태국룩. 게이샤룩, 테크노펑크룩, 테크노 카우걸룩 등의 동서양의 지리적 소외감을 통해 비권위적 다양한 시선을 제시함으로써, 다국적 자본주의와 함께 확장된 미적 체험을 하게 한다.; 둘째, 상호시간텍스트성 복식은 중세 엠파이어 드레스, 18세기 로코코시대의 robe'a la francaise, 미래적 제 3의 종 룩 등 동시적 몽환적 이미지를 통해 유희적 유토피아를 지향하였다.; 셋째, 상호계급텍스트성 복식은 그라피티룩, 펑크룩, 키치룩, 먼로 룩, 보깅(voguing), 에비타 룩 등 상하류층, 하위문화, 빈부, 권력의 유무를 병행인용하여, 좋은/나쁜 취향, 창녀/성녀 이분법을 해체하고 반부르조아적 저항과 물질주의를 찬양하는 탈계급적, 양면적 정체성을 구축하였다. ; 넷째, 상호종교텍스트성 복식은 상징적 가부장인 카톨릭교 텍스트를 인용하여 펑키크리스찬 룩, 에로틱 크리스찬 룩 등의 선/악, 신성성/관능성, 미추, 정숙성/비정숙성의 이분법, 비장미를 해체함으로써 예술의 자율성, 무의식이 강조된 쾌락주의적, 반권위주의적 정체성을 주장한다. 섹슈얼리티에 있어, 시선, 권력, 쾌락의 주체가 됨으로써, 미적 범주에 있어 선악, 미추, 정숙성과 비정숙성의 이분법을 해체함으로써, 유동적 자아를 구성한 마돈나 의상의 포스트모던 정체성은 여성에게 확대된 가능성을 제공하며 내부로부터 해체된 열린 복식을 지향한다.

• Journal of ILASS-Korea
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• v.14 no.2
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• pp.59-64
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• 2009

These experiments are close examination of spray characteristics that are continuous liquid jet and modulated liquid jet. The experiments were conducted using water, over a range of crossflow velocities from $42{\sim}l36\;m/s$, with modulation frequencies of $35.7{\sim}166.2\;Hz$. Between continuous crossflow jet and modulated cross-flow jet of penetration, breakup point, spray angle and macro spray shape are experimentally investigated with image analysis. In cross-flow field, main parameter of liquid jet for breakup was cross-flow stream rather than modulation effect. As oscillation of the periodic pressure that could make liquid jet moved up and down, the mixing efficiency was increased. Also, a bulk of liquid jet puff was detected at upper field of liquid surface. So, this phenomenon has a good advantage of mixing spray from concentration of center area to outer area. Because of modulation frequency, SMD inclination of the structured layer was evanescent. Cross-sectional characteristics of SMD at downstream area were non-structured distributions. Then cross-sectional characteristics of SMD size were about same tendency over a range that is effect of spray mixing. The tendency of volume flux value for various modulation frequency was same distribution. And volume flux was decreased when the modulation frequency increase.