• Communications of the Korean Mathematical Society
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• v.31 no.1
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• pp.101-113
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• 2016

In this article, we considered the stability of the following (${\alpha}$, ${\beta}$, ${\gamma}$)-derivation $${\alpha}D[x,y]={\beta}[D(x),y]+{\gamma}[x,D(y)]$$ and homomorphisms associated to the quadratic type functional equation $$f(kx+y)+f(kx+{\sigma}(y))=2kg(x)+2g(y),\;x,y{\in}A$$, where ${\sigma}$ is an involution of the Lie $C^*$-algebra A and k is a fixed positive integer. The Hyers-Ulam stability on unbounded domains is also studied. Applications of the results for the asymptotic behavior of the generalized quadratic functional equation are provided.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.698-703
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• 2000

In a computational fluid dynamics, the imposition of open boundary condition has an important part of the accuracy but it is not easy to find the optimal boundary rendition. This difficult is introduced by making artificial boundary in unbounded domairs. Such open boundary requires us to ensure the continuity of all primitive variables because the nature is in continuum. Here we introduce a revised well-conditioned open boundary condition particularly in FEM and apply it to various problems-entrainment, body force, short domains.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.475-480
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• 2007

For the propagation of elastic waves in unbounded domains, absorbing boundary conditions at the fictitious numerical boundaries have been proposed. In this paper we focus on both first- and second-order paraxial boundary conditions(PBCs) in the framework of variational approximations which are based on paraxial approximations of the scalar and elastic wave equations- We propose a penalty function method for the treatment of PBCs and apply these into finite element analysis. The numerical verification of the efficiency is carried out through comparing PBCs with Lysmer-Kuhlemeyer' s boundary conditions.

• 중국학논총
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• no.53
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• pp.1-16
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• 2017

The grammatical meaning of "了", a marker of aspects in Mandarin has been described differently among researchers, three of which are to express the end, a certain phase of event and the start of an event or a state. This paper consists of four parts. Set out below is a summary of main points of each part. The first chapter elaborates on the results of previous related studies, points out the purpose and meaning of the current study. Chapter two introduces marked "了" including concepts of the meaning and "Done", "complete whole", "realization" Corresponds to the case study. And explains syntactic and semantic features of the "了", highlights the look "of the了" problems of syntax and semantics, "了2" made three domains Limit 3 Including of the knowledge. This chapter holds that its grammartical meaning can be described as follows an event has taken place or a state has formed prior to a certain reference time, and that the grammartical meanings mentioned above can be considered sub - grammartical meanings of "了",which result from different prominence of the phases of an event. Chapter three explains tag component of the "了1", "了2". It discusses limited constraints, first place for "了" syntactic meaning, "The End" and "extension" of the opposition for "了" is looming around the root system, "了" and "着" sentence structure and semantic and syntactic forms. Chapter four discusses bounded features of the 了. It mainly focuses on "了"of bounded / unbounded function. It analyses the functions of components and explains a bounded function of "了1" and a bounded function of "了2". Chapter five is the conclusion. It consolidates and summarises the previous contents of the paper and points out the conclusion.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.123-130
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• 2015

This paper presents a new formulation for transient simulations of microwave propagation in heterogeneous unbounded domains. In particular, perfectly-matched-layers(PMLs) are introduced to allow for wave absorption at artificial boundaries used to truncate the infinite extent of the physical domains. The development of the electromagnetic PML targets the application to engineering mechanics problems such as structural health monitoring and inverse medium problems. To formulate the PML for plane electromagnetic waves, a complex coordinate transformation is introduced to Maxwell's equations in the frequency-domain. Then the PML-endowed partial differential equations(PDEs) for transient electromagnetic waves are recovered by the application of the inverse Fourier transform to the frequency-domain equations. A mixed finite element method is employed to solve the time-domain PDEs for electric and magnetic fields in the PML-truncated domain. Numerical results are presented for plane microwaves propagating through concrete structures, and the accuracy of solutions is investigated by a series of error analyses.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.303-309
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• 2007

For the propagation of elastic waves in unbounded domains, absorbing boundary conditions at the fictitious numerical boundaries have been proposed. In this paper we focus on both first and second order paraxial boundary conditions(PBCs) in the framework of variational approximations which are based on paraxial approximations of the scalar and elastic wave equations. We propose a penalty function method for the treatment of PBCs and apply these into finite element analysis. The numerical verification of the efficiency is carried out through comparing PBCs with Lysmer-Kuhlemeyer's boundary conditions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.14-19
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• 2008

This paper presents dynamic infinite element formulations which have been developed for soil-structure interaction analysis both in frequency and in time domains by the present authors during the past twenty years. Axisymmetric, 2D and 3D layered half-space soil media were considered in the developments. The displacement shape functions of the infinite elements were established using approximate expressions of analytical solutions in frequency domain to represent the characteristics of multiple waves propagating into the unbounded outer domain of the media. The proposed infinite elements were verified using benchmark examples, which showed that the present formulations are very effective for the soil-structure interaction analysis either in frequency or in time domain. Example applications to actual interaction problems are also given to demonstrate the capability and versatility of the present methodology.

• Spatial Information Research
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• v.19 no.1
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• pp.127-133
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• 2011

Recently, with the advances in sensor techniques and net work computing, Ubiquitous Sensor Network (USN) has been received a lot of attentions from various communities. The sensor nodes distributed in the sensor network tend to continuously generate a large amount of data, which is called stream data. Sensor stream data arrives in an online manner so that it is characterized as high-speed, real-time and unbounded and it requires fast data processing to get the up-to-date results. The data stream has many application domains such as traffic analysis, physical distribution, U-healthcare and so on. Therefore, there is an overwhelming need of a USN middleware for processing such online stream data to provide corresponding services to diverse applications. In this paper, we propose a novel USN middleware which can provide users both context-aware service and meaningful sequential patterns. Our proposed USN middleware is mainly focused on location based applications which use stream location data. We also show the implementation of our proposed USN middleware. By using the proposed USN middleware, we can save the developing cost of providing context aware services and stream sequential patterns mainly in location based applications.

• Earthquakes and Structures
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• v.3 no.3_4
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• pp.203-230
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• 2012

This paper presents results for impedance (and compliance) functions and input motions of foundations in a layered half-space computed on the basis of a procedure that combines a consistent transmitting boundary with continued-fraction absorbing boundary conditions which are accurate and effective in modeling wave propagation in various unbounded domains. The effects of obliquely incident seismic waves in a layered half-space are taken into account in the formulation of the transmitting boundary. Using the numerical model, impedance (and compliance) functions and input motions of rigid circular foundations on the surface of or embedded in a homogeneous half-space are computed and compared with available published results for verification of the procedure. Extrapolation methods are proposed to improve the performance in the very-low-frequency range and for the static condition. It is concluded from the applications that accurate analysis of foundation dynamics and soil-structure interaction in a layered half-space can be carried out using the enhanced consistent transmitting boundary and the proposed extrapolations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.2
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• pp.87-95
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• 2018

This paper introduces a new explicit spectral element method for the simulation of SH-waves in semi-infinite domains. To simulate the wave motion in unbounded domains, it is necessary to reduce the infinite extent to a finite computational domain of interest. To prevent the wave reflection from the trunctated boundaries, perfectly matched layer(PML) wave-absorbing boundary is introduced. The forward problem for simulating SH-waves in PML-truncated domains can be formulated as second-order PDEs. The second-order semi-discrete form of the governing PDEs is constructed by using a mixed spectral elements with Legendre-gauss-Lobatto quadrature method, which results in a diagonalized mass matrix. Then the second-order semi-discrete form is transformed to a first-order, whose solutions are calculated by the fourth-order Runge-Kutta method. Numerical examples showed that solutions of SH-wave in the two-dimensional analysis domain resulted in stable and accurate, and reflections from truncated boundaries could be reduced by using PML boundaries. Elastic wave propagation analysis using explicit time integration method may be apt for solving larger domain problems such as three-dimensional elastic wave problem more efficiently.