• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.200-202
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• 2003

In this paper, Gauss filter function is used to filter the N-S equation and the subgrid-scale Reynold stresses model is introduced to deduce the practical form of LES equation for 2-D case for flow calculation of hydraulic machine. Then the LES equation and its discrete form in computational field are obtained in the body-fitted coordinate system and the numerical calculation program is built. The incompressible turbulent flow in double-flow-conduits-sewage pump impeller is computed by using the abovementioned program, and then the distribution rules of velocity and pressure in flow field are obtained. Based on this, the designs of double-flow-conduits-sewage pump impeller are optimized.

• 한국해안해양공학회지
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• 제19권3호
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• pp.222-227
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• 2007

심해에서 생성된 최극해파가 파랑과 상호작용하는 현상에 대한 연구를 수행하였다. 이러한 파랑은 분산집중을 이용하여 산정하였다. 이러한 과정은 선형 및 비선형 방정식의 해를 구하여 얻을 수 있다. 상호작용에서 비선형성의 역할을 강조하였다.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.242-245
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• 2005

The rotating flow in the space between co-rotating disks is of considerable importance in information storage systems. Hard disk drivers(HDD) in computer are used extensively as data storage capacity. The trend in the computer industry to produce smaller disk drives rotating at higher speed requires an improved understanding of fluid motion in the space between disks. In this study, we have tried LES model for inner-disk flowfield to investigate the flow disturbance and the flow structure driven by co-rotating disks. The boundary pattern between inner region and outer region obtained lobe-shape structure clearly and its number has been validated on experimental data by our previous study. We obtain the spectra of velocity and pressure components with several frequencies. We revealed there are two kinds of disturbances, one is global wave propagation and another is local wave propagation on Ekman boundary layer.

• Wind and Structures
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• 제7권1호
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• pp.29-40
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• 2004

This study has focused on aerodynamics for a wind-resistance design about the single and tandem box girder sections to realize a super-long span bridge in the near future. Three-dimensional static analysis of flows around the fundamental single and tandem box girder sections with fairing is carried out by means of the IBTD/FS finite element technique with LES turbulence model. As the results of the analysis, computations have verified aerodynamic characteristics of both sections by the histories of aerodynamic forces, the separation and reattachment flow patterns and the surface pressure distributions. The relationship between the section shapes and the aerodynamic characteristics is also investigated in both sections. And the mechanism about the generation of fluctuating aerodynamic forces is discussed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 추계 학술대회논문집
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• pp.152-157
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• 2003

As computer capacity has been progressed continuously, the studies of the flow characteristics have been performing by the numerical methods actively. Recent numerical simulation has a tendency to require the higher-order accuracy in time, as well as in space. This tendency is more true in LES and acoustic noise simulation. In this study, 3-dimensional unsteady Incompressible Navier-Stokes equation was solved by numerical method using the fractional step method with the fourth order compact pade scheme to achieve high accuracy To validate the present code and algorithm, 3D flow-field around a cylinder was simulated. The drag coefficient and lift coefficient were computed and, then, compared with experiment. The present code will be tailored to LES simulation for more accurate turbulent flow analysis.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.123-126
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• 2013

Combustor development requires high fidelity simulation capable of predicting recirculation zone (RZ), temperature field, and pollutant emission. Swirling flow is widely used in combustor for its benefits in efficient mixing and flame stabilization by RZ. Large eddy simulation (LES) is used to calculate swirling flow in an expanding pipe [1], and shows higher accuracy than RANS. Reactive flow modeling using LES and flamelet model is validated with experiments by Barlow et al. [4] and Masri et al. [3]. Finally, heat transfer simulation of Samsung Techwin's combustor liner is presented.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.98-108
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• 2004

This study concerns a large eddy simulation (LES) of turbulent flow around a bluff body inside a sudden expansion cylindrical chamber, a configuration which resembles a premixed gas turbine combustor The simulation code is constructed by using the general coordinate system based on the physical contravariant velocity components. The Smagorinsky model is employed and the calculated Reynolds number is 5,000 based on the bulk velocity and the diameter of the inlet pipe. The combined grid technique and cylindrical grid are tested in the numerical simulation with complex geometry. The predicted turbulent statistics are evaluated by comparing with LDV measurement data. The numerical flow visualizations depict the behavior of turbulent mixing process behind the flame holder.

• 한국연극학
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• 제40호
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• pp.239-275
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• 2010

Cette ${\acute{e}}tude$ a pour but de proposer une $m{\acute{e}}thodologie$ de critique avec la $s{\acute{e}}miotique$ ouverte. La critique de $th{\acute{e}}{\hat{a}}tre$ commence ${\grave{a}}$ lire le $th{\acute{e}}{\hat{a}}tre$, l'analyse et juge son valeur. Il arrive souvent qu'on juge avec intutition. On dit que c'est une critique d'impressionnisme. Cette critique est subjective, mais pas objective. La $s{\acute{e}}miotique$ de Saussure offre la $m{\acute{e}}thodologie$ scientifique ${\grave{a}}$ la critique. A $c{\hat{o}}t{\acute{e}}$ de la critique d'impressionnisme qui est subjective, la $s{\acute{e}}miotique$ peut expliciter la raison objective. On ${\acute{e}}tait$ admiratif devant sa scientisme, pourtant $apr{\grave{e}}s$ quoi on critique sa non-$subjectivit{\acute{e}}$ et sa non-$historicit{\acute{e}}$. Dans l'opposition de $l^{\prime}objectivit{\acute{e}}$ et de la $subjectivit{\acute{e}}$, on tente de rechercher un model $int{\acute{e}}gr{\acute{e}}$ dialectiquement entre l'impressionisme(subjective) et la scientisme(objective). Pour cela, on doit aux Ecrits de linguistique $g{\acute{e}}n{\acute{e}}rale$ ($publi{\acute{e}}$ en 2002 chez Gallimard). Ces Ecrits nous aident ${\grave{a}}$ amener la $s{\acute{e}}miotique$ $ferm{\acute{e}}e$ sur la $s{\acute{e}}miotique$ ouverte et ${\grave{a}}$ $red{\acute{e}}couvrir$ la $pens{\acute{e}}e$ de Saussure. Ils nous font ouvrir un nouveau champ de recherche pour la $s{\acute{e}}miotique$ ouverte. L'essentiel de la $th{\acute{e}}orie$ saussurienne du signe $d{\acute{e}}pend$ de l'arbitraire et du circulaire du signe. On $red{\acute{e}}couvre$ la notion ${\acute{e}}largie$ du signe, dans Ecrits de linguistique $g{\acute{e}}n{\acute{e}}rale$, contre le courant majeur de linguistique et de structuralisme. Cette notion s'y focalise, ${\grave{a}}$ la valeur, ${\grave{a}}$ la $relativit{\acute{e}}$, ${\grave{a}}$ la $diff{\acute{e}}rence$ et au $syst{\grave{e}}me$. Avec elle, on tente d'adopter la $s{\acute{e}}miotique$ ouverte pour rechercher une $m{\acute{e}}thodologie$ de critique qui se veut objective et ${\grave{a}}$ la fois subjective. Il s'agit d'une difficile combinaison de l'impressionisme et de la scienticisme. Pour cela, la $m{\acute{e}}thodologie$ se $d{\acute{e}}veloppera$ en trois ${\acute{e}}tapes$. $1{\grave{e}}re$ ${\acute{e}}tape$: c'est lire le $th{\acute{e}}{\hat{a}}tre$ comme un signe total pour 1er jugement d'impressionnisme. $2{\grave{e}}me$ ${\acute{e}}tape$: c'est retrouver sa structure invisible dans la $relativit{\acute{e}}$ des signes. $3{\grave{e}}me$ ${\acute{e}}tape$: c'est juger, dans leur $relativit{\acute{e}}$, comment les $d{\acute{e}}tails$ de signes se fonctionnent. C'est lire les $d{\acute{e}}tails$ de signes et puis $r{\acute{e}}affirmer$ le jugement en $1{\grave{e}}re$ ${\acute{e}}tape$. Selon les $derni{\grave{e}}res$ deux ${\acute{e}}tapes$, on pourra comparer le premier jugement (impressif) et le dernier jugement (objectif), et enfin s'assumer comme critique. Selon la $m{\acute{e}}thodologie$ $propos{\acute{e}}e$, on pratique la critique sur ${\acute{e}}crit$ par Jean Genet, et mise en $sc{\grave{e}}ne$ par Lee Youn-Taek et par Park Jung-Hee. Pour la critique intertextuelle, on la fera en comparant les deux spectacles avec la $pi{\grave{e}}ce$ de Jean Genet. $D^{\prime}apr{\grave{e}}s$ la comparaison, Lee Youn-Taek met en $sc{\grave{e}}ne$ avec $fid{\acute{e}}lit{\acute{e}}$ la structre et les signes de $d{\acute{e}}tail$ de l'auteur, Park Jung-Hee change sa structre et ses signes pour mettre en $sc{\grave{e}}ne$ la $pi{\grave{e}}ce$ de Genet. Ils se $diff{\grave{e}}rent$ l'un et l'autre: Lee incite le discours de la classe sociale dans le spectacle, et Park y incite le discours du $d{\acute{e}}sir$. La $diff{\acute{e}}rence$ des signes dans la $relativit{\acute{e}}$ apporte la $diff{\acute{e}}rence$ de la signification de discours $th{\acute{e}}{\hat{a}}tral$, et enfin se font changer les significations de deux spectacles.

• 한국화재소방학회논문지
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• 제26권1호
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• pp.31-37
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• 2012

본 연구는 주거용 건축물의 열역학적 수치해석모델을 검토하는데 목적이 있다. 화재하중과 화재강도는 성능설계의 사용이 증가함에 따라 건축물 화재안전 설계에 중요한 요소으로 대두되고 있으며, 컴퓨터 성능의 발전으로 수치해석을 통한 예측이 가능해 지고 있다. 주거 가연물의 연소특성을 예측하기 위해 각가연물의 수치해석용 모델을 설계하였다. 해석된 결과를 검증하기 위해 수치해석의 결과를 실물 화재실험의 결과와 비교하였다. 수치해석을 위해 FDS5를 사용하였으며, 난류해석을 위해 LES모델이 적용하였다. 검증결과 화염전파 현상 및 온도곡선은 실험결과와 정성적으로 잘 일치함을 확인하였다.

• 한국항공우주학회지
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• 제38권2호
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• pp.99-110
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• 2010

강한 압축성을 갖는 유동의 DES 해석에서, 일반적인 경험상수 $C_{DES}$ 값 0.65를 사용할 경우 경계층 내에서 인위적으로 LES 모드로 수행된다. 본 연구에서는 S-A DES 모델에서 RANS 모드 보호를 위하여 사용되는 난류 길이와 벽거리 비의 분포 함수를 이용한 $C_{DES}$의 동적 결정 방법을 제시하였다. 동적 $C_{DES}$ 결정식을 초음속 기저 유동장에 적용한 결과 다른 모델 상수를 사용한 기존의 연구 결과에 비하여 우수한 예측을 보여주었다.