• Journal of the Korean Mathematical Society
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• v.54 no.2
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• pp.479-491
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• 2017

We investigate the zeros of Epstein zeta functions associated with positive definite quadratic forms with rational coefficients in the vertical strip ${\sigma}_1$ < ${\Re}s$ < ${\sigma}_2$, where 1/2 < ${\sigma}_1$ < ${\sigma}_2$ < 1. When the class number h of the quadratic form is bigger than 1, Voronin gave a lower bound and Lee gave an asymptotic formula for the number of zeros. Recently Gonek and Lee improved their results by providing a new upper bound for the error term when h > 3. In this paper, we consider the cases h = 2, 3 and provide an upper bound for the error term, smaller than the one for the case h > 3.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.12 s.255
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• pp.1626-1633
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• 2006

In the present paper, in the context of the meshless interpolation of a moving least squares (MLS) type, a novel method which uses primary and secondary nodes in the domain and on the global boundary is introduced, in order to improve the accuracy of solution. The secondary nodes can be placed at any location where one needs to obtain a better resolution. The support domains for the shape functions in the MLS approximation are defined from the primary nodes, and the secondary nodes use the same support domains. The shape functions based on the MLS approximation, in an integration domain, have a single type of a rational function, which reduces the difficulty of numerical integration to evaluate the weak form. The present method is very useful in an adaptive calculation, because the secondary nodes can be easily added and moved without an additional mesh. Several numerical examples are presented to illustrate the effectiveness of the present method.

• Bulletin of the Korean Mathematical Society
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• v.44 no.4
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• pp.683-689
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• 2007

Let $\mathcal{B}$ be a certain Banach space consisting of analytic functions defined on a bounded domain G in the complex plane. Let ${\varphi}$ be an analytic polynomial or a rational function and let $M_{\varphi}$ denote the operator of multiplication by ${\varphi}$. Under certain condition on ${\varphi}$ and G, we characterize the commutant of $M_{\varphi}$ that is the set of all bounded operators T such that $TM_{\varphi}=M_{\varphi}T$. We show that $T=M_{\Psi}$, for some function ${\Psi}$ in $\mathcal{B}$.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.6
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• pp.11-18
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• 2018

Isogeometric concept is introduced to find out the optimum layout of plane structure under free vibration. Eigenvalue problem is formulated and numerically solved in order to obtain natural frequencies and mode shapes of plane structures. For the exact geometric expression of the structure, the Non-Uniform Rational B-spline Surface (NURBS) basis functions is employed and it is also used to define the material density functions. A node-wise design variables is adopted to deal with the updating of material density in topology optimization (TO). The definition of modal strain energy is employed to achieve the maximization of fundamental frequency through its minimization. The verification of the proposed TO technique is performed by a series of benchmark test for plane structures.

• Archives of design research
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• v.16 no.3
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• pp.299-308
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• 2003

The existing market patterns and social structures have been changed according to the trends of digital and informational society of the 21st century. The characteristics of the consumption market is that the balance of power moves from enterprises to consumers. As consumers’ demands are diversified according to life quality enhancement, many products are based on main aspects of human experiences, emotions and values. Standardized functions and services of products cannot capture consumers to a great extent any more. A notable aspect is that consumers want products or services that can oner movable experiences. Future products must appeal to emotion, not to reason of consumers. Now consumers purchase styles, experiences and stories contained in products, not products themselves. That is, the key to decision to purchase products is the satisfaction of emotional values. Users'emotions diversified due to the development of industrial designs demand the development of new designs that can represent new trends of users. User-centered values imply the change of people's purchasing trends. This indicates that there is a need to change physical aspects such as price or functions into individual emotions and characters. In addition, studies are required on design concepts to pursue new emotional values, apart from functional type designs. It is time for designers to suggest initiative and rational directions for this changing era.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.5
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• pp.177-185
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• 2020

The building energy performance indicator, called Energy Performance Index (EPI), has been used for the past decades in South Korea. It has a list of design variables assigned with weighting factors (a, b). Unfortunately, the current EPI method is not performance-based but very close to a prescriptive rating. With this in mind, this study aims to propose a new performance-based EPI method. For this purpose, a global sensitivity analysis method, Sobol, is employed. The Sobol method is suitable for complex nonlinear models and can decompose all the output variance due to every input. The Sobol sensitivity index of each variable is defined as 0 to 1 (0 to 100%), and the sum of all sensitivity indices is equal to 1 (100%). In this study, an office building was modeled using EnergyPlus and then the Latin Hypercube Sampling (LHS) was conducted to generate a surrogate model to EnergyPlus. The sensitivity index was suggested to replace weight (a) in the existing EPI. In addition, the discrete weight (b) in the existing EPI was replaced by a set of continuous regression functions. Due to the introduction of the sensitivity index and the continuous regression functions, the new proposed approach can provide far more accurate outcome than the existing EPI (R²: 0.83 vs. R²: 0.01 for cooling, R²: 0.66 vs. R²: 0.01 for total energy). The new proposed approach proves to be more rational, objective and performance-based than the existing EPI method.

• Steel and Composite Structures
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• v.37 no.6
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• pp.663-678
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• 2020

This paper proposes a novel topology optimization method generating multiple materials for external linear plane crack structures based on the combination of IsoGeometric Analysis (IGA) and eXtended Finite Element Method (X-FEM). A so-called eXtended IsoGeometric Analysis (X-IGA) is derived for a mechanical description of a strong discontinuity state's continuous boundaries through the inherited special properties of X-FEM. In X-IGA, control points and patches play the same role with nodes and sub-domains in the finite element method. While being similar to X-FEM, enrichment functions are added to finite element approximation without any mesh generation. The geometry of structures based on basic functions of Non-Uniform Rational B-Splines (NURBS) provides accurate and reliable results. Moreover, the basis function to define the geometry becomes a systematic p-refinement to control the field approximation order without altering the geometry or its parameterization. The accuracy of analytical solutions of X-IGA for the crack problem, which is superior to a conventional X-FEM, guarantees the reliability of the optimal multi-material retrofitting against external cracks through using topology optimization. Topology optimization is applied to the minimal compliance design of two-dimensional plane linear cracked structures retrofitted by multiple distinct materials to prevent the propagation of the present crack pattern. The alternating active-phase algorithm with optimality criteria-based algorithms is employed to update design variables of element densities. Numerical results under different lengths, positions, and angles of given cracks verify the proposed method's efficiency and feasibility in using X-IGA compared to a conventional X-FEM.

• Journal of Korean Medical classics
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• v.33 no.1
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• pp.197-205
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• 2020

Objectives : We analyzed the descriptions of Doek(德)·Qi(氣)·Saeng(生)·Jeong(精)·Sin(神)·Hon(魂)·Baek(魄)·Sim(心)·Ui(意)·Ji(志)·Sa(思)·Ji(智)·Ryeo(慮)·Ji(智) which are the concepts mentioned in the beginning of the ≪Lingshu·Benshen≫. Methods : We reinterpreted this verse in ≪Lingshu·Benshen≫ from the viewpoint of evolution and development of mental function and considered it in relation to the knowledge of modern psychology and brain science. Results & Conclusions : The reproductive essence of the parents are combined, primitive essence (元精) is created and simultaneously primitive spirit is born. Primitive spirit first differentiates into Hon and Baek. Hon and Baek are instinctive mental functions. Up to this point, because the process is completed before birth, primitive spirit, Hon, and Baek are innate spirit. Ui, Ji, Sa, Ryeo and Ji are the rational thinking abilities as mental functions that develop actively after birth. This is called conscious spirit and acquired spirit. Analyzing the contents of , it can be said that the mental function is divided into four layers of primitive spirit-Baek-Hon-conscious spirit.

• Lingua Humanitatis
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• v.5
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• pp.193-217
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• 2003

This paper aims to infer conversational implicatures from Chief Priest Sung-chul′s Nirvanic song in light of the Buddhist view of language and its communicative functions. Zen-dialogs in which nirvanic songs are classified are defined as rational dialogs, which in fact observe the rules of conversation such as the ones proposed by Paul Grice (1975) even though they apparently ignore the rules. This paper also addresses the formal characteristics of the Priest′s nirvanic song and argues that the song exploits the rules of conversation using the whole song as an implicature trigger. Taking it for granted that Chief Priest Sung-chul holds the view on language and its communicative functions just as specified in the Doctrine of Mere Consciousness, which is one of the major tenets of Korean Buddhism, especially of the Chogye order, this paper tries to explicitly show and systematize the language-to-world relationship, which is only alluded to in the Doctrine of Mere Consciousness. This paper also refines the assertion of the doctrine as to the nature of language, which maintains that language is not associated with either the mind or outer objects (that is, an unassociated dharma), and is "a shared thing among shared things." This shows that language continuously interacts with the mind in a different way from the ones in which associated mental activities (caittas) interact with the mind and that accordingly, language is "an unshared thing among shared things."

• Wind and Structures
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• v.7 no.6
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• pp.421-447
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• 2004

This paper presents a time domain approach for predicting buffeting response of long suspension bridges under skew winds. The buffeting forces on an oblique strip of the bridge deck in the mean wind direction are derived in terms of aerodynamic coefficients measured under skew winds and equivalent fluctuating wind velocities with aerodynamic impulse functions included. The time histories of equivalent fluctuating wind velocities and then buffeting forces along the bridge deck are simulated using the spectral representation method based on the Gaussian distribution assumption. The self-excited forces on an oblique strip of the bridge deck are represented by the convolution integrals involving aerodynamic impulse functions and structural motions. The aerodynamic impulse functions of self-excited forces are derived from experimentally measured flutter derivatives under skew winds using rational function approximations. The governing equation of motion of a long suspension bridge under skew winds is established using the finite element method and solved using the Newmark numerical method. The proposed time domain approach is finally applied to the Tsing Ma suspension bridge in Hong Kong. The computed buffeting responses of the bridge under skew winds during Typhoon Sam are compared with those obtained from the frequency domain approach and the field measurement. The comparisons are found satisfactory for the bridge response in the main span.