• Title/Summary/Keyword: Green's function

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An Analysis of Green Space Base for Networking in Daegu Metropolitan Municipality (녹지연계망 조성을 위한 거점 분석 -대구광역시의 사례 -)

  • 나정화;사공정희
    • Journal of the Korean Institute of Landscape Architecture
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    • v.29 no.6
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    • pp.37-49
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    • 2002
  • The objective of this research was an investigation of the important green spaces in Daegu and to present the basic frame of green network in Daegu. Present the condition of the significant green spaces is as follows: In the 3km radius of the city center, the isolation and discontinuation of the green spaces was extensive, caused by crowding of houses and funeral parlours. Consequently, the isolation relaxation which leads to the additional creation of the green spaces and a buffering plan were demanded. In the transfer area of a 3∼6km radius, which is located between the city center's congested area and the suburb green spaces, the significant green spaces had high connection and buffering characteristic, but in the northwest and the south, serious discontinuation appeared between the suburb green spaces and the city conte green spaces. In the 6∼9km radius, the suburb important green spaces accomplished the function which extended the back core green spaces to the city center area. But creation of buffering green spaces was necessary in part because of proximity to the resident area. The results suggest a connection between green spaces on the base of the distribution of the important green spaces, were as follows: In the 3km radius, irregular direction lines appeared while a schedule one direction line appeared in 3∼6km and 6∼9km radius. The discontinued parts of the green network were caused by industrial complexes, house crowding, and cultivation areas. Consequently, reservation and creation plans of green spaces in response to this were demanded. Through the additional creation of green spaces in the discontinued parts, the basic frame of green network in Daegu was the radiation annular form. And it was suitable to activate the parks and the general green spaces.

An Optimum Choice of Approximation Path for Derivation of New Class of Closed-Form Green's Functions (새로운 형태의 Closed-Form 그린함수의 유도를 위한 근사 경로의 최적선택)

  • Lee Young-Soon;Kim Eui-Jung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.4 s.95
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    • pp.418-426
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    • 2005
  • Based upon three level approximation and the steepest descent path(SDP) method, we consider an optimum choice of approximation path for derivation of new class of closed-flrm Green's functions which can lead to the analytic evaluation of MoM(Method of Moment) matrix elements. It is observed that the present method can give more accurate evaluation of the spatial Green's functions than the previous method, even without the advance investigation of the spectral functions, over a wide frequency range. In order to check the validity of the present method, some numerical results are presented.

Comparative Study on Themes of Research Papers on the Research Trends of Parks and Green Spaces in Japan and Korea

  • Naoko Fujita;Chong Soo-Jin;Yoichi Kumagai;Akio Shimomura
    • Journal of the Korean Institute of Landscape Architecture International Edition
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    • no.2
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    • pp.81-87
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    • 2004
  • The objective of our research was an international comparison focusing on studies conducted on parks and green spaces undertaken in Japan and Korea. We also aim to clarify the similarities and differences between the two countries and consider the key features of the researches on the field of landscape architecture. We compared the recent trends of Japanese institute with Korean observed in the theme of research papers adopt title of them. The research period spanned approximately twenty years, from 1980 to 2003. We employed the Table of Contents information search system to research academic journal articles and to select the journals that included articles with the key words [park(s)] or [green space(s)] in their title. We chronologically arranged the journals for each country, based on the total number of journals and classification categories. We then conducted a comparative examination among the two countries. We also contributed information on the circumstances behind the formulation or amendment of some policies and laws and we checked the results against the research trend. Among the selected journals, the number of papers was the highest by the Institute of Landscape Architecture. But the reason for increase of the number of papers on green spaces in Japanese journals was not published by the Institute of Landscape Architecture but by the City Planning Institute and the Architecture Institute. In Japan, the papers on parks categorized under historical study were the highest among all categories. On the other hand, in Korean journals, papers on parks categorized under historical study were few. A similar trend was recognized in papers on green spaces. Every society is concerned with the study of function and effect. However, some exact differences have been observed by category classification. In Japan, the percentage of function and effect papers on parks was less than those on green spaces. In Korea, both percentages for these groups were high. The category of system and policy accounted for $17\%$ of the papers on green spaces in Korea. This result was higher than the number of papers on green spaces and parks in Japan and parks in Korea. Recently, the number of papers focusing on large-scale green space system has decreased in Japan. The trend in the study of parks and green spaces on a regional scale or at an individual level will be closely monitored. Systems and modeling studies have been focusing in Korea. The understanding between the administration and the citizens was peculiar to each country.

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Criterion to Choose Efficient Far-Field Approximation of Dyadic Green's Function for Impedance Plane like Ocean Surface (해수면 같은 임피던스 평면 위의 다이아딕 그린함수에 관한 효율적 원거리 근사공식 선택 기준)

  • Lee, Hyunsoo;Koh, Il-Suek;Yoon, Jong Suk;Kim, Tae Hyung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.28 no.2
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    • pp.147-154
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    • 2017
  • The impedance approximation has been widely used to model an earth surface such as ocean surface. In calculation of the dyadic Green's function for the impedance half plane, Sommerfeld integral and its partial derivatives are required. It is known that two far-field approximation of the Sommerfeld integral can be represented in terms of Legendre or Laguerre polynomials. Hence, a criterion is required to choose one of two far-field approximations for a given application, which can be expressed in a complex plane of the surface impedance. Also, we approximate the required partial derivatives of Sommerfeld integral and numerically verify the accuracy of the approximation.

Frequency Domain Analysis for Hydrodynamic Responses of Floating Structure using Desingularized Indirect Boundary Integral Equation Method (비특이화 간접경계적분방정식 방법을 이용한 부유식 구조물의 유체동역학적 거동에 대한 주파수영역 해석)

  • Oh, Seunghoon;Jung, Dongho;Cho, Seok-kyu;Nam, Bo-woo;Sung, Hong Gun
    • Journal of the Society of Naval Architects of Korea
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    • v.56 no.1
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    • pp.11-22
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    • 2019
  • In this paper, a Rankine source method is applied and validated to analyze the hydrodynamic response of a three-dimensional floating structure in the frequency domain. The boundary value problems for radiation and diffraction problem are solved by using a desingularized indirect boundary integral equation method (DIBIEM). The DIBIEM is simpler and faster than conventional methods based on the numerical surface integration of Green's function because the singularities of Green's function are located outside of fluid regions. In case of floating structure with complex geometry, it is difficult to desingularize the singularities of Green's function consistently. Therefore a mixed approach is carried out in this study. The mixed approach is partially desingularized except singularities of the body. Wave drift loads are calculated by the middle-field formulation method that is mathematically simple and has fast convergence. In order to validate the accuracy of the developed program, various numerical simulations are carried out and these results are analyzed and compared with previously published calculations and experiments.

A NEW BIHARMONIC KERNEL FOR THE UPPER HALF PLANE

  • Abkar, Ali
    • Journal of the Korean Mathematical Society
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    • v.43 no.6
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    • pp.1169-1181
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    • 2006
  • We introduce a new biharmonic kernel for the upper half plane, and then study the properties of its relevant potentials, such as the convergence in the mean and the boundary behavior. Among other things, we shall see that Fatou's theorem is valid for these potentials, so that the biharmonic Poisson kernel resembles the usual Poisson kernel for the upper half plane.