• 천문학회보
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• 제46권2호
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• pp.68.1-68.1
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• 2021

We study galaxy evolution with the large-scale environment with confirmed galaxy clusters from multi-object spectroscopy (MOS) observation. The observation was performed with Inamori Magellan Areal Camera and Spectrograph (IMACS) mounted on the 6.5 m Magellan/Baade telescope in Las Campanas Observatory. With the MOS observation, we spectroscopically confirm 34 galaxy clusters, including three galaxy clusters discovered in Kim et al. (2016) and 11 of them have halo mass of > 10^14.5 M_◉. Among the confirmed clusters, 12 galaxy clusters are part of large-scale structure at z ~ 0.9, and their size stretches to 40 Mpc co-moving scale. In this study, we checked the 'web feeding model,' which postulates that more linked (with their environment) galaxy clusters have less quenched populations by investigating the correlation between properties of confirmed galaxy clusters and the large-scale structure environment. Lastly, we found that galaxy clusters that make up the large-scale structure have larger and widely spread values of total star formation density (ΣSFR/M_halo) than typical clusters at similar redshifts.

• 천문학회보
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• 제35권1호
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• pp.83.1-83.1
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• 2010

In the last meeting of KAS, we reported the first statistical study of Faraday rotation measure (RM) in the large-scale structure of the universe using the data of cosmological structure formation simulations. With a turbulence dynamo model for the intergalactic magnetic field (IGMF), we predicted that the root mean square of RM through filaments is \sim 1 rad/m^2. Future radio observatories such as the Square Kilometer Array (SKA) could detect this signal level. However, it is known that the typical foreground galactic RM is a few tens and less than ten rad/m^2 in the low and high galactic latitudes, respectively. So the RM in the large-scale structure could be detected only after the foreground galactic RM is removed. In this talk, we show how we remove the foreground galactic RM and what we obtain from the masked data, by using some noise models and masking techniques. Our results can be used to simulate future RM observations by SKA, and eventually to constrain the origin and evolution of the IGMF in the large-scale structure.

• Journal of information and communication convergence engineering
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• 제19권3호
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• pp.155-160
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• 2021

Differential evolution is an efficient algorithm for solving continuous optimization problems. However, its performance deteriorates rapidly, and the runtime increases exponentially when differential evolution is applied for solving large-scale optimization problems. Hence, a novel cooperative coevolution differential evolution based on Spark (known as SparkDECC) is proposed. The divide-and-conquer strategy is used in SparkDECC. First, the large-scale problem is decomposed into several low-dimensional subproblems using the random grouping strategy. Subsequently, each subproblem can be addressed in a parallel manner by exploiting the parallel computation capability of the resilient distributed datasets model in Spark. Finally, the optimal solution of the entire problem is obtained using the cooperation mechanism. The experimental results on 13 high-benchmark functions show that the new algorithm performs well in terms of speedup and scalability. The effectiveness and applicability of the proposed algorithm are verified.

• 한국군사과학기술학회지
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• 제10권4호
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• pp.20-29
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• 2007

The engagement control software embedded in the weapon control computer of the fire control center for air defense missile system is large-scale real-time software. The use of typical software development methodologies is not appropriate to develop such large-scale embedded software in terms of reusability, reliability, and productivity for the reason that it is significantly complicated, and highly dependent on hardware platforms and developers. In this paper, a model-based software architecture using components based on UML 2.0 for the engagement control software is presented in order to solve these problems. This software architecture is verified using the black-box test, the scenario-based test, and the Ethernet packet monitoring test methods. The results demonstrate that the developed software architecture can be employed to enhance reusability, maintainability, and productivity of large-scale embedded software.

• 한국해안해양공학회지
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• 제10권2호
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• pp.83-92
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• 1998

대격자망 수치모형에서 저항물체에 의한 유수저항을 평가하기 위하여, 항력으로부터 유도된 drag stress를 수심적분된 Reynolds 방정식에 도입하였다. 그리고, 해석해가 존재하는 조건에 대한 다양한 수치실험을 통하여 본 모형의 적용성 및 문제점을 검토하였다. 단일물체의 경우, 수치해는 해석해에 대하여 유속의 크기에 있어서$\pm$10% 정도의 오차범위를 나타내는 좋은 일치를 보였으며 후류폭의 크기도 전 경우에 있어서 해석해와 잘 일치 하였다. 또한, 열을 이룬 물체에 대한 항력계수와 와동점성계수가 정확하게 결정된다면, 본 모형은 열을 이룬 물체 배후에서 평균류의 흐름분포를 평가하는 데 효율적으로 이용될 수 있을 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제8권4호
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• pp.257-264
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• 2004

공동주택 수익모델의 가치를 형성하는 요소 중 영향도가 큰 물리적 요소는 주택의 평형변화로서 이를 중심으로 리모델링의 대안을 제안한다. 이에 따라 본 연구에서는 공동주택의 가치형성요인과 공간구성기법을 이용한 큰 평형의 세대를 작은 평형의 세대로 분할하는 모델과 작은 평형의 세대를 통합하여 큰 평형의 세대로 변환하는 모델의 수익모델을 설정하여 경제성은 '보통'이상 '양호'한 것으로 나타났으며, 경제성 평가값은 할인율이 증가함에 따라 감소하며 리모델링의 경제성이 우수해지는 것으로 나타남을 알 수 있다.

• 콘크리트학회논문집
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• 제16권6호
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• pp.867-873
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• 2004

It has been known that debonding failures between CFS(Carbon Fiber Sheet) and concrete in the strengthened RC beams are initiated by the peeling of the sheets in the region of combined large moment and shear forces, being accompanied by the large shear deformation after flexural cracks. These shear deformation effects are seldom occurred in small-scale model tests, but debondings due to the large shear deformation effects are often observed in a full-scale model tests. The premature debonding failure of CFS, therefore, must be avoided to confirm the design strength of full-scale RC beam in strengthening designs. The reinforcing details, so- called 'U-Shape fiber wrap at mid-span' which wrapped the RC flexural members around the webs and tension face at critical section with CFS additionally, were proposed in this study to prevent the debonding of CFS. Other reinforcing detail, so called 'U-Shape fiber wrap at beam end' were included in this tests and comparisons were made between them.

• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.254-263
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• 2015

In this study, numerical simulations are carried out to investigate the dynamic SGS model effects in a Kerosene-LOx coaxial swirl injector under high pressure conditions. The turbulent model is based on large-eddy simulation (LES) with real-fluid transport and thermodynamics. To assess the effect of the dynamic subgrid-scale (SGS) model, the dynamic SGS model is compared with that of the algebraic SGS model. In a swirl injector under supercritical pressure, the characteristics of temporal pressure fluctuation and power spectral density (PSD) present comparable discrepancies dependant on the SGS models, which affect the mixing characteristics. Mixing efficiency and the probability density (PDF) function are conducted for a statistical description of the turbulent flow fields according to the SGS models. The back-scattering of turbulent kinetic energy is estimated in terms of the film thickness of the swirl injector.

• Interaction and multiscale mechanics
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• 제2권3호
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• pp.235-261
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• 2009

This study illustrates the differences between the elasto-plastic cap model and Lade's model with Cosserat rotation through the analyses of two large-scale geosynthetic-reinforced soil (GRS) retaining wall tests that were brought to failure using a monotonically increasing surcharge pressure. The finite element analyses with Lade's model were able to reasonably simulate the large-scale plane strain laboratory tests. On average, the finite element analyses gave reasonably good agreement with the experimental results in terms of global performances and shear band occurrences. In contrast, the cap model was not able to simulate the development of shear banding in the tests. In both test simulations the cap model predicted failure loads that were substantially less than the measured ones.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.634-637
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• 2008

A large eddy simulation with an explicit filter on unstructured mesh is presented. The flow filed is semi-implicitly marched by a fractional step method. Spatial discretization of the solver is designed to guarantee the second order accuracy. An isotropic explicit filter is adopted for measuring the level of subgrid scale velocity fluctuation. The filter is linearity-preserving and has second order commutation error. The developed subgrid scale model is basically eddy viscosity model which depends on the explicitly filtered fields and needs no additional ad hoc wall treatment, such as van Driest damping function. For the validation, the flows in a channel and a pipe are calculated and compared to experimental data and numerical results in the literature.