• Title, Summary, Keyword: 비균질

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비(非) Friedmann 우주

  • Hyeon, Jeong-Jun;Lee, Sang-Gak;Min, Ho-Gi
    • Publications of The Korean Astronomical Society
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    • v.3 no.1
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    • pp.20-29
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    • 1987
  • 균질(均質) 등방성(等方性) 공간(空間)을 전제하는 Friedmann 우주의 타당성은 Planck 시기($t_p{\sim}10^{-43}sec$) 이진으로 소급시킬 수 없으므로 시초의 비(非)(Non) Friedmann 우주가 가능하다. 본 연구는 우주시초의 특이성과 관련되는 균질 우주와 비균질 우주의 특성, 지평선과 inflation의 관계를 개관한 다음, $t{\sim}t_p$의 양분자(量子論) 요동(搖動)이나 $t>t_p$의 GUT 상전이(相轉移)로 생기는 inflation 계기에 파생(派生)하는 시공(時空)의 거품들이 이루는 비균질(非均質) 우주의 가능성과 인간원리(人問原理)에 기반을 둔 우주 집단의 관련을 고찰한다.

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Study of Mobile Phone Antenna for SAR Reduction (SAR 저감을 위한 이동통신 단말기 안테나 연구)

  • 정민석;이범선
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • pp.123-126
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    • 2001
  • 본 논문에서는 균질, 비균질 두부 모델에 대한 SAR 평가 방법들을 비교 분석한 후, 균질 두부모델에 대한 SAR 데이터가 비균질 두부 모델의 그것과 유사함을 확인한다. 이러한 결과는 근거로 두부 모델을 가정하여, 설계된 λ/8 Back-mounted PIFA 사용시의 SAR 데이터와 기존의 안테나 사용시의 SAR 데이터를 비교 분석한다. 이러한 비교 분석 결과 기존의 폴더형 안테나가 구조 특성상 전형적인 통화자세에서 방사부가 두부에서 멀어 1g-SAR와 10g-SAR가 λ/8 Back-mounted PIFA 보다 약 50% 작으나 전체 두부 흡수율은 오히려 높음을 알 수 있었다.

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Natural Frequencies for Inhomogeneous Beams by Differential Transformation (미분변환에 의한 비균질 보의 진동해석)

  • Mun, Kwon-Kyung;Jae, Shin-Yung;Ryu, Yung-Soon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.617-621
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    • 2001
  • This paper presents the application of the technique of differential transformation to find the vibration frequencies for inhomogeneous beams with one sliding support, the other clamped and the other pinned boundary conditions. Numerical calculations are carried out. The frequencies obtained from the differential-transformation solutions are compared to published results to demonstrate the accuracy and flexibility of the method.

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Thickness Assessment of Adhesive Layer in Inhomogeneous Layer by Guided Wave (유도초음파에 의한 비균질 적층의 접합층두께 평가)

  • Cho, Youn-Ho;Ham, Hyo-Sik;Choi, Heung-Ho
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.4
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    • pp.391-397
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    • 2001
  • The guided wave propagation in inhomogeneous multi-layered structures is experimentally explored based on theoretical dispersion curves. It turns out that proper selection of incident angel and frequency is critical for guided wave generation in multi-layered structures. Theoretical dispersion curves greatly depend on adhesive zone thickness, layer thickness and material properties. It was possible to determine the adhesive zone thickness of an inhomogeneous multi-layered structure by monitoring experimentally the change of dispersion curves.

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Boundary/Finite Element Analysis of the Seismic Wave Amplifications Due to Inhomogeneous Alluvial Deposits (비균질 퇴적층으로 인한 지진파 증폭의 경계/유한요소 해석)

  • 김효건;손영호;김종주;최광규
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.4
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    • pp.591-597
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    • 1999
  • 본 연구에서는 비 균질 퇴적층으로 인한 지진파의 증폭에 대한 경계/유한요소 해석을 수행하였다. 수치해석을 위해, 비 균질 퇴적층은 8절점 등 매개 변수 유한요소 사용하여 모델링하였고, 그 주위의 균질 반무한 지반은 3절점 등매개 변수 경계요소를 사용하여 모델링하였다. 경계요소와 유한요소의 접촉면에서, 표면 력의 평형조건과 변위의 적합 조건에 의해 두 개의 요소를 결합하는 알고리듬을 개발하였다. 수치해석의 영향인자로서 SH파, P파와 SV파의 입사각, 무 차원 진동수 그리고 반무한 지반과 퇴적층사이의 전단 파 속도 비와 질량밀도 비를 고려하였다.

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A Study on the Heterogeneity in Multi-player VR Games : focused on (멀티플레이어 가상현실 게임에 나타난 비균질성 연구 : <더 플레이룸 VR>을 중심으로)

  • Park, Eun-Kyung;Nam, Yang-Hee
    • Journal of Korea Game Society
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    • v.16 no.6
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    • pp.151-162
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    • 2016
  • The purpose of this paper is to identify the significance of heterogeneity in multi-player VR games. Heterogeneity is a concept of multi-player mode that a game uses the immersive VR and non-immersive system at the same time. As immersive VR device has become more commercial, multi-player VR games try to use heterogeneity strategically. is the best example to explain a new phenomenon, so this paper analyses by using a revised and reinforced MDA framework. As a result, we can find heterogeneity concept not only in the separation of player's interface, but also in the division of play patterns and experiences within a game itself.

Model Tests on the Characteristics of Lateral Behavior of Steel Pipe Pile in Homogeneous and Nonhomogeneous Soil Conditions (균질 지반과 비균질 지반에서 강관 모형말뚝의 수평거동 특성에 관한 모형실험)

  • 김병탁;김영수
    • Geotechnical Engineering
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    • v.14 no.6
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    • pp.153-166
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    • 1998
  • This paper shows the results of a series of model tests on the behavior of steel pipe pile which is subjected to lateral and inclined loads in homogeneous and non-homogeneous Nak-dong River sands. Non-homogeneous soil consisted of two layers, upper and lower layer. The purpose of the present paper is to investigate the effect of ratio of lower layer height to embedded pile length, ratio of soil modules of upper layer to lower layer and inclined load on the behavior of single pile. These effects can be quantified only by the results of model tests. As a result. in non-homogeneous sand soil, it is shown that the lateral behavior depends upon the ratio of soil modules of upper layer to lower layer more than other factors. And it was found that the relationship between the deflection ratio of non-homogeneous sand to homogeneous sand and the ratio of lower layer height to embedded pile length can be fitted to exponential function of H/L by model tests results. For the inclined load applied, it is shown that the bending moment-depth relationship is not similar to the case of laterally loaded pile and the depth of maximum bending moment at relative density of 90% increases about 70% more than the pile only loaded laterally.

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Physicochemical Properties of Physically Modified Rice Starch by Homogenizer (균질기를 이용한 물리적 변성 쌀 전분의 이화학적 특성)

  • Han, Myung-Ryun;Kim, Myung-Hwan
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.5
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    • pp.700-706
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    • 2005
  • The objectives of this research were to analyze physicochemical properties of physically modified rice starch which was prepared by hydro-shear homogenizer and ultrasonic homogenizer. The 5:1 of water to starch ratio, 20,500 rpm of hydro-shear homogenizer, and 5 sec of pulse and 40 kHz of frequency of ultrasonic homogenizer, which were operated for 10 min. The 1/3 of size reduction of raw rice starch and gelatinized rice starch, and reduced of particle size were achieved by above processing conditions. The homogenization of raw rice starch and gelatinized rice starch were higher values of specific area, transmittance, solubility and swelling power than control. While, these had lower value of apparent viscosity than control. In raw rice starch, the gelatinization characteristics of ultrasonic homogenizer treated rice starch had some higher values of gelatinization temperature, peak temperature and enthalpy than those of control. While, those of hydro-shear homogenizer treated rice starch had similar values to those of control.

Nonlinear Analysis for the Prediction of Lateral Behavior of Single Piles in Non-homogeneous Sandy Soil (비균질 사질토 지반에서 단일말뚝의 수평거동 예측을 위한 비선형 해석기법)

  • 김영수;김병탁;허노영
    • Journal of the Korean Geotechnical Society
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    • v.16 no.4
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    • pp.5-16
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    • 2000
  • THe purpose of this paper is to suggest the analytical method which can predict lateral nonlinear behavior in non-homogeneous soil using the coefficient of soil resistance and ultimate soil resistance. Those parameters are obtained through back analysis on the base of the results of a series of model tests.Analytical method of Chang is more or less difficult to predict nonlinear behavior in non-homogeneous sol. So, in this study, for the prediction of nonlinear behavior the compositive analytical method which apply the p - y curve to Chang model is suggested. Also, the program is developed to predict nonlinear behavior using the compositive analytical method and it can be used to calculated the deflection, bending moment and soil reaction with DFM in non-homogeneous soil. To establish applicability of the suggested analytical method, the results of model tests and field tests and Pentagon2D finite element program are compared with those of the compositive analytical method. In the analysis values of the coefficient of soil reaction and ultimate soil resistance are also applied to the case of non-homogeneous soil. Lateral defection calculated using the compositive analytical method has been found to be in good agreement with values measured in field and model load tests.

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