• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.45-54
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• 2003

A hyperbolic two-phase, two-fluid equation system developed in the previous work has been implemented in an existing nuclear safety analysis code, MARS. Although the implicit treatment of interfacial pressure force term introduced in momentum equation of the hyperbolic equation system is required to enhance the numerical stability, it is very difficult to implement in the code because it is not possible to maintain the existing numerical solution structure. As an alternative, two-step approach with stabilizer momentum equations has been selected. The results of a linear stability analysis by Von-Neumann method show the equivalent stability improvement with fully-implicit solution method. To illustrate the applicability, the new solution scheme has been implemented into the best-estimate thermal-hydraulic analysis code, MARS. This paper also includes the comparisons of the simulation results for the perturbation propagation and water faucet problems using both two-step method and the original solution scheme.

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.280-283
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• 2011

In the present work, a new approach is proposed for via interconnects of semiconductor devices, where multi-wall carbon nanotubes (MWCNTs) are used instead of conventional metals. In order to implement a selective growth of carbon nanotubes (CNTs) for via interconnect, the buried catalyst method is selected which is the most compatible with semiconductor processes. The cobalt catalyst for CNT growth is pre-deposited before via hole patterning, and to achieve the via etch stop on the thin catalyst layer (ca. 3nm), a novel 2-step etch scheme is designed; the first step is a conventional oxide etch while the second step chemically etches the silicon nitride layer to lower the damage of the catalyst layer. The results show that the 2-step etch scheme is a feasible candidate for the realization of CNT interconnects in conventional semiconductor devices.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.3
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• pp.123-137
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• 1993

In this paper, an integrated approach is proposed to generate gouging-free Cartesian tool paths for machining sculptured surfaces from 3D measurement data. The integrated CAD/CAM system consists of two modules : offset surface module an Carteian tool path module. The offset surface module generates an offset surface of an object from its 3D measurement data, using an offsetting method and a surface fitting method. The offsetting is based on the idea that the envelope of an inversed tool generates an offset surface without self-intersection as the center of the inversed tool moves along on the surface of an object. The surface-fitting is the process of constructing a compact representation to model the surface of an object based on a fairly large number of data points. The resulting offset surtace is a composite Bezier surface without self-intersection. When an appropriate tool-approach direction is selected, the tool path module generates the Cartesian tool paths while the deviation of the tool paths from the surface stays within the user-specified tolerance. The tool path module is a two-step process. The first step adaptively subdivides the offset surface into subpatches until the thickness of each subpatch is small enough to satisfy the user-defined tolerance. The second step generates the Cartesian tool paths by calculating the intersection of the slicing planes and the adaptively subdivided subpatches. This tool path generation approach generates the gouging-free Cartesian CL tool paths, and optimizes the cutter movements by minimizing the number of interpolated points.

• Language and Information
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• v.13 no.1
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• pp.127-143
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• 2009

Tough-construction is, undoubtedly, one of the most puzzling syntactic problems in the history of transformational grammar. Various approaches have been proposed including Deletion approaches (Akmajian, 1972; Lasnik and Fiengo, 1974) and movement approaches. Among the movement approaches, Chomsky (1977; 1981) argues for movement of null Operator, and Hornstein (2001) argues for a two-step movement equipped with Sideward movement. Most recently, Schueler (2004) and Hartman (2009) each have also argued for a kind of movement approach. With the development of the Minimalist syntax (Chomsky, 1995; Chomsky, 2000; Chomsky, 2001), tough-construction, an age old problem in the description of grammar, turns into another round toward to a more satisfactory answer. By examining the most recent competing analyses of tough-constructions, this paper defends and extends Schueler's (2004) analysis, rather than Hartman's (2009) two step movement approach. Furthermore, this paper proposes that tough-subject originates from the intermediate CP internal Spec-TopicP position rather than from the iterated CP layer (Authier, 1992). This approach has more descriptive power than it was originally argued for in Schueler (2004) and is a step closer toward Minimalism insofar as the conception of government is no longer utilized.

• Advances in Computational Design
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• v.1 no.3
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• pp.235-251
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• 2016

We have performed a design optimization of a stiffened panel with curvilinear stiffeners using an artificial neural network (ANN) residual kriging based surrogate modeling approach. The ANN residual kriging based surrogate modeling involves two steps. In the first step, we approximate the objective function using ANN. In the next step we use kriging to model the residue. We optimize the panel in an iterative way. Each iteration involves two steps-shape optimization and size optimization. For both shape and size optimization, we use ANN residual kriging based surrogate model. At each optimization step, we do an initial sampling and fit an ANN residual kriging model for the objective function. Then we keep updating this surrogate model using an adaptive sampling algorithm until the minimum value of the objective function converges. The comparison of the design obtained using our optimization scheme with that obtained using a traditional genetic algorithm (GA) based optimization scheme shows satisfactory agreement. However, with this surrogate model based approach we reach optimum design with less computation effort as compared to the GA based approach which does not use any surrogate model.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.7
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• pp.3317-3320
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• 2016

Purpose: To assess the success rates of two step loop electrosurgical excision procedure (LEEP) compared with conventional cold conization procedures for decreasing positive surgical margins. Materials and Methods: This study was conducted on 70 patients who underwent colposcopic evaluation in Zeynep Kamil Women and Children's Health Training and Research Hospital between 2013-2015 with indications of CIN 2/3 or persistent CIN 1 for more than 2 years. The study included age matched groups of patients with similar histopathololical lesions who underwent cold conization (n=40) or LEEP (N=30). Results: Comparison of tissue characteristics between the two groups revealed significantly higher deepest depth and lower volume of tissue removed by the two step LEEP. Ectocervical positivity rate was similar between groups (1/39 versus 0/29, P>0.05), while endocervical surgical margin positivity rate was significantly higher in the cold conization group (9/39 versus 0/29, P<0.05). Surgical margin positive cases were significantly older than the cases with negative margins (P<0.05). Conclusions: Two step LEEP made it easier to reach the squamocolumnar junction in the endocervical region with lower blood loss and applicability in office settings. Our study suggests to use two step approach in cases with high grade and glandular CIN.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3276-3285
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• 2024

This paper introduces the creation of a module for Uncertainty Quantification (UQ) specifically designed for VVER analysis through the implementation of the STREAM/RAST-V two-step approach. The aim was to expand the range of use by developing a UQ module tailored for analyzing VVER. This research presents two innovative computational functionalities: (1) development of a library for the pin-based pointwise energy slowing down method (PSM), and (2) extension of the analysis area to study hexagonal-geometry fuel assemblies. The proposed UQ scheme was evaluated through verification using UAM benchmark, and comparative analysis between codes using SCALE 6.2.2 for. STREAM provides an accuracy comparable to that of SCALE 6.2.2. Additionally, a PSM covariance library was utilized in the calculations, achieving 0.7941% and 0.7907% accuracies in the hot full power and hot zero power calculations, respectively. To assess the UQ sequences in the two-step method, the STREAM/RAST-V calculation scheme was verified using the STREAM lattice code. To conclude, this study furnishes comprehensive insights into the development of the UQ module within the two-step method for VVER analysis, and it validates its performance through utilization of the UAM benchmark.

• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.237-241
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• 2001

Our goal is to present a simple volume-of-fluid type interface-tracking algorithm to compressible two-phase flow in two space dimensions. The algorithm uses a uniform underlying Cartesian grid with some cells cut by the tracked interfaces into two subcells. A volume-moving procedure that consists of two basic steps: (1) the update of volume fractions in each grid cell at the end of the time step, and (2) the reconstruction of interfaces from discrete set of volume fractions, is employed to follow the dynamical behavior of the interface motion. As in the previous work with a surface-tracking procedure for general front tracking (LeVeque & Shyue 1995, 1996), a high resolution finite volume method is then applied on the resulting slightly nonuniform grid to update all the cell values, while the stability of the method is maintained by using a large time step wave propagation approach even in the presence of small cells and the use of a time step with respect to the uniform grid cells. A sample preliminary numerical result for an underwater explosion problem is shown to demonstrate the feasibility of the algorithm for practical problems.

• Structural Engineering and Mechanics
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• v.27 no.6
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• pp.683-696
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• 2007

This article is concerned with the presentation of a time-domain BEM approach applied to the solution of the scalar wave equation for 2D problems. The basic idea is quite simple: the basic variables of the problem at time $t_n$ (potential and flux) are computed with the results related to the potential and to its time derivative at time $t_{n-1}$ playing the role of "initial conditions". This time-marching scheme needs the computation of the potential and its time derivative at all boundary nodes and internal points, as well as the entire discretization of the domain. The convolution integrals of the standard time-domain BEM formulation, however, are not computed; the matrices assembled, only at the initial time interval, are those related to the potential, flux and to the potential time derivative. Two examples are presented and discussed at the end of the article, in order to verify the accuracy and potentialities of the proposed formulation.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.284-291
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• 2000

Interlocking software used in the electronic interlocking has been implemented through the structured approach until now. But there was the demerit that interlocking software has some problem in the standardization and the maintenance because of the limit in structured approach. Object-Oriented method overcoming this demerit was specified in the design step and the analysis step. There were object model, dynamic model and functional model in the analysis step and there were also two steps which were system design and object design in the design step. In this paper, Interlocking software was designed using Object-Oriented method to improve the standardization and the maintenance of the electronic interlocking. The electronic interlocking was analyzed with object modeling, dynamic modeling and functional modeling.