• Journal for History of Mathematics
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• v.30 no.1
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• pp.31-50
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• 2017

This study analyses on the history of uniform convergence, and discusses its educational implications. First, this study inspects 'overflowing of the Euclidean methodology' which was suggested by Lakatos as a cause of tardy appearance of uniform convergence, and reinterprets that cause in the perspective of 'symbolization'. Second, this study looks into the emergence of uniform convergence of Seidel and Weierstrass in this viewpoint of symbolization. As a result, of analysis, we come to know that the definition of uniform convergence had been changed into the theory of 'domain and graph' from that of 'point and function value' by the location change of the quantifier. As these results, this study puts forward an educational suggestion from an angle of epistemological obstacle, concept definition and concept image.

• Korean Journal of Optics and Photonics
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• v.2 no.4
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• pp.186-192
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• 1991

For the micro-lithography using a excimer laser beam $(\lambda\leq0.248$\mu\textrm{m})$. a mirror system consisting of four spherical surfaces with reductlon magnification 5X is designed. Initially the aplanat, flat field and the distortion free condition of the system are analytically investigated within Seidel 3rd order aberrations. And the computer-aided optimization technique has been employed for the further improved performance of the system. The final system has N.A. of 0.15 and image field diameter 3.3 mm, and has the diffraction-limited performance for KrF eximer laser beam.

• Journal of Ecology and Environment
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• v.47 no.2
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• pp.27-34
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• 2023

Background: The understanding of ecosystem services can be quantified and qualitative to assess the impacts of changes in the ecosystem to support human well-being. In the Democratic People's Republic of Korea, sustainable use of ecosystem services has attracted the interest of a range of decision-makers. However, although there is a concern for biodiversity, natural ecosystem, and their services, linking ecosystems with conservation planning remains challenging. Results: This study assessed the first qualitative ecosystem services provided by the Mundok wetland with decision makers of the West/Yellow Sea region. Furthermore, this study applied the Rapid Assessment Wetland Ecosystem method to support natural resources management, improving living conditions. We identified that cultural and supporting services index are highly provided, but preparing a plan to increase the provisioning and regulating services in Mundok wetland is necessary. Conclusions: The assessment results can provide helpful information for ecosystem services assessment, habitat conservation, conservation planning, and decision-making at local level.

• Korean Journal of Optics and Photonics
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• v.16 no.5
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• pp.423-427
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• 2005

In this paper, we propose easily tooling method for Seidel third order aberration, which are not well utilized in actual design process due to the complication of mathematical operation and the difficulty of understanding Seidel third order aberration theory, even though most insightful and systematic means in pre-designing for the initial data of optimization. First, using paraxial ray tracing and Seidel third order aberration theory, spherical aberration coefficient is derived for a two-mirror system with a finite object distance. The coefficient, which is expressed as a higher-order nonlinear equation, consists of design parameters(object distance, two curvatures, and inter-mirror distance) and effective focal length(EFL). Then, the expressed analytical equation is solved by using a computer with numerical analysis method. From the obtained numerical solutions satisfying the nearly zero coefficient condition($<10^{-6}$), linear fitting process offers a linear relationship called the curvature linear equation between two mirrors. Consequently, this linear equation has two worthy meanings: the equation gives a possibility to obtain initial design data for optimization easily. And the equation shows linear relationship to a two-mirror system with a finite object distance under the condition of corrected third order spherical aberration.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.1-6
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• 1996

To simulate the characteristics of magnetic exchange coupling at the interface of MR/TbCo thin films, the directions of magnetizations were calculated by minimizing energy in the films. Newton method and Gauss-Seidel method were used. The width of M-H curve increased with TbCo anisotropy constant, and with the thickness of the transition region of TbCo layer. Hysteresis loop width became extremely narrow (less than 10 Oe of coercivity), when the TbCo transition region length was $400\;\AA$. Also the hysteresis loop of films with low interfacial exchange coupling constant was similiar to that of short transition region length. When interfacial exchange coupling constant was 1/100 of perfect coupling, hysteresis loop showed a coercivity of less than 10 Oe. Comparing the measured hysteresis loop of a fabricated sample with that of simulated one, exchange coupling con¬stant could be estimated.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.113-121
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• 2002

Nowadays, developed camera, camcorder, CCTV and copier system accept a wide angle and a telephoto lens, and have an excellent capacity. Also, it is small as using aspheric surface. In this paper, after we evaluate and analyze two-group zoom lens system and three-group zoom lens system for camera, we refer to it, and design three-group zoom lens system for camera. Therefore, when we design a zoom lens system for camera, we use a symmetrical system. As using an aspheric surface, we can try to a miniaturization and an efficient improvement. We use optical valuable measure methods, a ray intercept plot, MTF and Seidel coefficient. So, we can confirm to have a similar level to compare with reference model.

• Tribology and Lubricants
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• v.28 no.4
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• pp.160-166
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• 2012

This paper presents a Reynolds equation solver for hydrostatic gas bearings, implemented to run on graphics processing units (GPUs). The original analysis code for the central processing unit (CPU) was modified for the GPU by using the compute unified device architecture (CUDA). The red-black Gauss-Seidel (RBGS) algorithm was employed instead of the original Gauss-Seidel algorithm for the iterative pressure solver, because the latter has data dependency between neighboring nodes. The implemented GPU program was tested on the nVidia GTX580 system and compared to the original CPU program on the AMD Llano system. In the iterative pressure calculation, the implemented GPU program showed 20-100 times faster performance than the original CPU codes. Comparison of the wall-clock times including all of pre/post processing codes showed that the GPU codes still delivered 4-12 times faster performance than the CPU code for our target problem.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.8
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• pp.1122-1133
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• 2003

Numerical characteristics of implicit upwind schemes, such as upwind ADI, line Gauss-Seidel (LGS) and point Gauss-Seidel (LU) algorithms, for Navier-Stokes equations have been investigated. Time-derivative preconditioning method was applied for efficient convergence at low Mach/Reynolds number regime as well as at large grid aspect ratios. All the algorithms were expressed in approximate factorization form and von Neumann stability analysis was performed to identify stability characteristics of the above algorithms in the presence of high grid aspect ratios. Stability analysis showed that for high aspect ratio computations, the ADI and LGS algorithms showed efficient damping effect up to moderate aspect ratio if we adopt viscous preconditioning based on min-CFL/max-VNN time-step definition. The LU algorithm, on the other hand, showed serious deterioration in stability characteristics as the grid aspect ratio increases. Computations for several practical applications also verified these results.

• Journal of computational fluids engineering
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• v.21 no.1
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• pp.10-18
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• 2016

Numerical boundary conditions are as important as the governing equations when analyzing the fluid flows numerically. An explicit boundary condition method updates the solutions at the boundaries with extrapolation from the interior of the computational domain, while the implicit boundary condition method in conjunction with an implicit time integration method solves the solutions of the entire computational domain including the boundaries simultaneously. The implicit boundary condition method, therefore, is more robust than the explicit boundary condition method. In this paper, steady compressible 2-Dimensional Navier-Stokes solver is developed. We present the implicit boundary condition method coupled with LU-SGS(Lower Upper Symmetric Gauss Seidel) method. Also, the explicit boundary condition method is implemented for comparison. The preconditioning Navier-Stokes equations are solved on unstructured meshes. The numerical computations for a number of flows show that the implicit boundary condition method can give accurate solutions.

• The Journal of Engineering Research
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• v.3 no.1
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• pp.85-95
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• 1998

In this study, we consider a recursive procedure to obtain the stationary probability distribution for analyzing Coxian queueing networks with finite queues. This network deals with multiple class customers. Due to the state space representing multiple class customers, the sub-matrices corresponding to states can not be square matrices and can not be inverted. Therefore, we introduce more complex recursive method to avoid the singular problem. The open queueing network that we study consists of 3 parallel first-level sources linked to a single second level queue. We consider two types of schemes for entering a queue. The first scheme is assumed to be the first-blocked-first-enter (FBFE) and the second scheme is the higher-priority-first-enter (HPFE). Arrival and service times are assume to have a Coxian distribution with two phases. Comparison between the resulting using Gauss-Seidel method and recursive procedure will be shown.