• 한국항공우주학회지
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• 제34권8호
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• pp.47-54
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• 2006

본 연구에서는 Lagrangian 단계와 Remap 단계로 이루어진 Two-step Eulerian 기법에 적용되는 수치기법에 대해 살펴보고, 이를 구현하였다. 요소 값은 donor cell 과 van Leer 기법으로 이류처리 하였고, 절점 값은 Simplifed ALE [SALE] 기법으로 이류처리 하였으며, 재료 경계면은 Simple Line Interface Calculation [SLIC] 기법으로 결정하였다. 또한, 프로그램 구현 과정과 Lagrangian 단계와 Remap 단계의 연결 시 주의 깊게 고려해야할 사항들에 대해 자세히 기술하였다. 본 연구를 통해 구현된 Two-step Eulerian 코드의 검증을 위해, 순수 Lagrangian 기법, 그리고 상용코드의 결과와 비교하여 해석 결과의 정확성을 검증하였다.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1320-1327
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• 2006

Parallel procedure and performance of two-step Eulerian code have not been reported sufficiently yet even though it was developed and utilized widely in the impact simulation. In this study, parallel strategy of two-step Eulerian code was proposed and described in detail. The performance was evaluated in the self-made linux cluster computer. Compared with commercial code, a relatively good performance is achieved. Through the performance evaluation of each computation stage, remap is turned out to be the most time consuming part among the other part such as FE processing, communication, time marching etc.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1235-1241
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• 2006

A new hydrocode which is still under development using Lagrangian, Eulerian and arbitrary Lagrangian-Eulerian operators, has been described. The three operators are implemented into a single framework by incorporating the sequential three stages of Lagrangian, remesh and remap stages. Several numerical schemes used for each operator are discussed briefly in this paper. In order to evaluate the characteristics of each operator, the Taylor Impact Test has been simulated using each operator and the results are compared. Currently the code is 1st order accuracy in the material interface tracking algorithm and can not handle multimaterial in the mixed cell. The areas of possible enhancement of the code are also discussed.

• Mycobiology
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• 제36권3호
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• pp.161-166
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• 2008

The retrotransposon marY1 is a gypsy family retroelement, which is detected ubiquitously within the fungal taxonomic groups in which mushrooms are included. To utilize marY1 as a molecular marker for the DNA fingerprinting of mushrooms, oligonucleotides marY1-LTR-L and marY1-LTR-R were designed on the basis of highly conserved regions from the multiple sequence alignment of 30 marY1 sequences retrieved from a nucleotide sequence database. In accordance with $\underline{Re}trotransposon$ $\underline{M}icrosatellite$ $\underline{A}mplified$ $\underline{P}olymorphism$ (REMAP) fingerprinting methodology, the two oligonucleotides were utilized together with the short sequence repeat primers UBC807 and UBC818 for polymerase chain reaction using templates from different mushroom genomic DNAs. Among the tested oligonucleotides, the marY1-LTR-L and UBC807 primer set yielded the greatest amount of abundance and variation in terms of DNA band numbers and patterns. This method was successfully applied to 10 mushroom species, and the primer set successfully discriminated between different commercial mushroom cultivars of the same strains of 14 Pleurotus ostreatus and 16 P. eryngii. REMAP reproducibility was superior to other popular DNA fingerprinting methodologies including the random amplified polymorphic DNA method.

• 한국지구과학회지
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• 제45권4호
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• pp.292-303
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• 2024

We study quasi-spherical, supersonic accretion flows around black holes using high-accuracy numerical simulations. We describe a code, the Lagrangian Total Variation Diminishing (TVD), and a remap routine to address a specific issue in the Advection Dominated Accretion Flow (ADAF) that is, appropriately handling the angular momentum even near the inner boundary. The Lagrangian TVD code is based on an explicit finite difference scheme on mass-volume grids to track fluid particles with time. The consequences are remapped on fixed grids using the explicit Eulerian finite-difference algorithm with a third-order accuracy. Test results show that one can successfully handle flows and resolve shocks within two to three computational cells. Especially, the calculation of a hydrodynamical accretion disk without viscosity around a black hole shows that one can conserve nearly 100% of specific a ngular momentum in one-and two-dimensional cylindrical coordinates. Thus, we apply this code to obtain a numerically similar ADAF solution. We perform simulations, including viscosity terms in one-dimensional spherical geometry on the non-uniform grids, to obtain greater quantitative consequences and to save computational time. The error of specific angular momentum in Newtonian potential is less than 1% between r~10r_s and r~10⁴ r_s, where r_s is sink size. As Narayan et al. (1997) suggested, the ADAFs in pseudo-Newtonian potential become supersonic flows near the black hole, and the sonic point is r_sonic~5.3r_g for flow with α =0.3 and γ=1 .5. Such simulations indicate that even the ADAF with γ=5/3 is differentially rotating, as Ogilvie (1999) indicated. Hence, we conclude that the Lagrangian TVD and remap code treat the role of viscosity more precisely than the other scheme, even near the inner boundary in a rotating accretion flow around a nonrotating black hole.

• 한국군사과학기술학회지
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• 제11권5호
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• pp.116-123
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• 2008

Hydrocodes are large computer programs that can be used to solve a wide variety of highly transient problems such as high-speed impact and explosion events. This paper describes the recent activity to develop a Multi-material hydrocode in Korea. The code consists of two stages; Lagrangian, and remap stages. Although a sophisticated contact algorithm has been developed for Lagrangian calculations, a relatively simple mechanics at the interfaces of materials are used in the multi-material Eulerian code. Volume of fluid interface reconstruction methods are used to resolve the interfaces between different materials. For the advection stage of the cell centered properties, one-dimensional hyperbolic equation is used. Test problems demonstrated here are the high-speed impact/penetration and explosion problems.

• 한국멀티미디어학회논문지
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• 제11권6호
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• pp.737-745
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• 2008

In this paper, a novel neighborhood metric of histogram equalization (HE) algorithm for contrast enhancement is presented. We present a refinement of HE using neighborhood metrics with a general framework which orders pixels based on a sequence of sorting functions which uses both global and local information to remap the image greylevels. We tested a novel sorting key with the suggestion of using the original image greylevel as the primary key and a novel neighborhood distinction metric as the secondary key, and compared HE using proposed distinction metric and other HE methods such as global histogram equalization (GHE), HE using voting metric and HE using contrast difference metric. We found that our method can preserve advantages of other metrics, while reducing drawbacks of them and avoiding undesirable over-enhancement that can occur with local histogram equalization (LHE) and other methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권5호
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• pp.423-443
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• 2009

We present the design and implementation of a unique sensing and actuation application -- the Illuminator: a sensor network-based intelligent light control system for entertainment and media production. Unlike most sensor network applications, which focus on sensing alone, a distinctive aspect of the Illuminator is that it closes the loop from light sensing to lighting control. We describe the Illuminator's design requirements, system architecture, algorithms, implementation and experimental results. The system uses the Illumimote, a multi-modal and high fidelity light sensor module well-suited for wireless sensor networks, to satisfy the high-performance light sensing requirements of entertainment and media production applications. The Illuminator system is a toolset to characterize the illumination profile of a deployed set of fixed position lights, generate desired lighting effects for moving targets (actors, scenic elements, etc.) based on user constraints expressed in a formal language, and to assist in the set up of lights to achieve the same illumination profile in multiple venues. After characterizing deployed lights, the Illuminator computes optimal light settings at run-time to achieve a user-specified actuation profile, using an optimization framework based on a genetic algorithm. Uniquely, it can use deployed sensors to incorporate changing ambient lighting conditions and moving targets into actuation. Experimental results demonstrate that the Illuminator handles various high-level user requirements and generates an optimal light actuation profile. These results suggest that the Illuminator system supports entertainment and media production applications.