• Title/Summary/Keyword: 불규칙 계수

Search Result 168, Processing Time 0.028 seconds

Calculation of the Peak-delay Force Reduction of Multi-Directional Random Waves Acting on a Long Caisson Breakwater (장대 케이슨 방파제에 작용하는 다방향 불규칙파랑의 파력 평활화 계수 산정)

  • Jung, Jae-Sang;Kim, Bum-Hyung;Ha, Tae-Min;Cho, Yong-Sik
    • 한국방재학회:학술대회논문집
    • /
    • 2010.02a
    • /
    • pp.66.2-66.2
    • /
    • 2010
  • 장대 케이슨 방파제에 작용하는 다방향 불규칙파랑의 파력 평활화 계수를 계산하였다. 다방향 불규칙파랑의 주파수 스펙트럼으로는 Bretschneider-Mitsuyasu 스펙트럼을 사용하였고, 방향 스펙트럼은 Mitsuyasyu 타입의 스펙트럼을 적용하였다. 계산 결과 단일 케이슨의 길이가 길수록, 주파향의 입사각이 클수록 평활화 계수는 감소하였다. 다양한 에 대해서도 계산하였으며, 가 클수록 평활화계수는 규칙파와 비슷한 경향을 보였다.

  • PDF

Calculation of the Peak-delay Force Reduction Parameter of Multi-Directional Random Waves Acting on a Long Caisson Breakwater (장대 케이슨 방파제에 작용하는 다방향 불규칙파랑의 파력감소계수 산정)

  • Jung, Jae-Sang;Kim, Bum-Hyung;Kim, Hyung-Jun;Cho, Yong-Sik
    • Journal of Korea Water Resources Association
    • /
    • v.43 no.10
    • /
    • pp.843-850
    • /
    • 2010
  • By employing multi-directional random waves, a parameter controlling the force acting on a long caisson breakwater is investigated in detail. Both JONSWAP (Joint North Sea Wave Project) and asymmetric directional spectra are adopted for frequency and directional spectra. It is found that the parameter decreases as the length of caisson and the angle of main direction of incident waves increase. Furthermore, the parameter is much similar to that of regular waves as the maximum spreading parameter $s_{max}$ increases. The parameter, however, decreases as asymmetry parameter ${\mu}$ increases when the main direction of incident waves is oblique to the breakwater.

Scale Factor Error and Random Walk Characteristics of a Body Dither Type Ring Laser Gyro (몸체진동형 링레이저 자이로의 환산계수 오차 및 불규칙잡음 특성)

  • 심규민;정태호;이호연
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.2 no.1
    • /
    • pp.139-149
    • /
    • 1999
  • In this paper, we estimate the scale factor error and random walk characteristics of the ring laser gyro which has the body dither for Lock-in compensation. And then, we compared those results with the static test results for 28cm square ring laser gyro which has about 0.5 deg/sec static Lock-in. In the case of sinusoidal body dither, dynamic Lock-in occurs periodically at the points where the gyro output pulse becomes the integer multiples of body dither frequency. The width of dynamic Lock-in is changed by variation of dither amplitude, and, between the width of dynamic Lock-in which occurs at the even multiple points of body dither frequency and that at the odd muliple points of body dither frequency, it has 180o phase difference. Generally random body dither is adopted to compensate for dynamic Lock-in. Then if the irregularity is not large enough, the scale factor error by dynamic Lock-in is not vanished. And if the irregularity is large enough, the scale factor error decreases, but random walk becomes larger relatively. And we confirmed that the larger body dither amplitude, the smaller random walk.

  • PDF

A Novel Approach to Improving the Performance of Randomly Perturbed Sensor Arrays (불규칙하게 흔들리는 센서어레이의 성능향상을 위한 새로운 방법)

  • Chang, Byong-Kun
    • The Journal of the Acoustical Society of Korea
    • /
    • v.14 no.1E
    • /
    • pp.65-72
    • /
    • 1995
  • The effects of random errors in array weight and sensor positions on the performance of a Linearly constrained linear sensor array is analyzed in a weight vector space. It is observed that a nonorthogonality exists between an optimum weight vector and the steering vector of an interference direction du e to random errors. A novel approach to improving the nulling performance by compensating for the nonorthogonality is proposed. Computer simulation results are presented.

  • PDF

Change of Nearshore Random Waves in Response to Sea-level Rise (해수면 상승에 따른 연안 지역 불규칙파의 변화)

  • Cheon, Se-Hyeon;Suh, Kyung-Duck
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.25 no.4
    • /
    • pp.244-254
    • /
    • 2013
  • In this study, a method has been developed for estimating the change of nearshore random waves in response to sea-level rise, by extending the method proposed for regular waves by Townend in 1994. The relative changes in wavelength, refraction coefficient, shoaling coefficient, and wave height for random waves are presented as functions of relative change in water depth. The changes in wavelength and refraction coefficient are calculated by using the significant wave period and principal wave direction in the regular-wave formulas. On the other hand, the changes in shoaling coefficient and wave height are calculated by using the formulas proposed for shoaling and transformation of random waves in the nearshore area including surf zone. The results are proposed in the form of both formulas and graphs. In particular, the relative change in wave height is compared with the result for regular waves.

Hydraulic Experiments on Transmission Coefficients for Vertical Structure under Intermediate Water Depth Condition (중간수심역 조건에서 직립식 구조물의 전달파고계수 산정에 관한 수리실험)

  • Kim, Young-Taek;Lee, Jong-In
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.27 no.5
    • /
    • pp.345-352
    • /
    • 2015
  • Two-dimensional hydraulic model experiments on vertical structures were conducted to investigate wave transmission characteristics under irregular wave condition. The formula about transmission coefficient for the vertical structure was suggested and the results were compared with Goda(1969). Since Goda(1969)'s tests were conducted based on regular waves, the results showed the discrepancy with this study. The Goda's results were relatively higher than the results from the present study. An influence parameter was quantitatively suggested in this study to consider the effect of structural design factors such as the width of structures, the water depth, and the wave length on the wave transmission, while Goda(1969) suggested the mean, upper and lower limits of parameters for the vertical wall(d=h). The transmission coefficients and energy conservation for zero-freeboard conditions were analyzed.

조석조건에서 불규칙파의 변이

  • 유동훈;강찬수
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
    • /
    • 1998.09a
    • /
    • pp.36-39
    • /
    • 1998
  • 불규칙파를 스펙트럼파로 파악하여 조석 조건하 천해역에서 천수, 굴절, 회절, 마찰 및 쇄파 등에 의하여 불규칙파가 변이하는 현상을 해석하였다. 지배방정식은 에너지보존식과 파수백타보존식인데 파수벡타보존식에 회절효과를 고려하는 항을 포함하였다. 스텍트럼형상을 재현하기 위하여는 선형누적법을 사용하였으며, 스펙트럼파에 대한 대표 마찰계수를 간단히 산정하는 약산식을 사용하여 마찰손실효과를 고려하였다. (중략)

  • PDF

Flutter Control of Flexible Structure under Random Atmospheric Disturbance (불규칙한 대기교란을 받는 유연한 구조물의 플러터 제어)

  • Oh, Soo-Young;Kim, Yong-Kwan;Cho, Kyoung-Lae;Heo, Hoon;Cho, Yun-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2000.06a
    • /
    • pp.1210-1215
    • /
    • 2000
  • Investigation is performed on the stability of general form of dynamic system under colored noise random disturbance whose damping and stiffness are varying in irregular manner along time, which is a preliminary result in the course of research on the characteristic and the control of the stochastic system. Adopted physical model is airfoil under random atmospheric disturbance, which becomes a "time-varying system" whose the governing equation is derived via F-P-K approach in stochastic sense. Control performance and effect of 'Heo-stochastic controller for colored noise' is studied. Also stochastic feature of flutter boundary is discussed as well.

  • PDF

Electromagnetic Wave Propagation Characteristics from Large Scale Random Rough Surfaces (큰 규모의 불규칙 조면에 의한 전자파 전파 특성)

  • Yoon Kwang-Yeol;Chai Yong-Yoong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.17 no.4 s.107
    • /
    • pp.393-399
    • /
    • 2006
  • In this paper we applied a ray tracing method to estimate the scattering characteristics from large scale random rough surfaces. For the electromagnetic field evaluation, we have used the diffracted coefficient of the knife edge diffraction for the diffracted rays and Fresnel's reflection coefficients in connection with reflected rays. In addition, we examine to search for the traced rays using the imaging method which can be obtained all rays to arrived at receivers accurately and the diffracted field from rough surfaces is considered. Numerical examples have been carried out for the scattering characteristics of an ocean wave-like rough surface and delay spread characteristics of a building-like surface. In the present work we have demonstrated that the ray tracing method is effective to numerical analysis of a rough surface scattering.

Dynamics Responses of Railway Bridges for Track Irregularities (궤도의 불규칙성을 고려한 철도교량의 동적응답분석)

  • 박흥석;이용선;이상호;김상효
    • Computational Structural Engineering
    • /
    • v.11 no.3
    • /
    • pp.253-262
    • /
    • 1998
  • 본 연구에서는 경부고속철도의 주요 교량형식인 PSC 박스교량을 3차원 뼈대요소를 사용하여 모형화하였으며, 궤도불규칙성의 형상은 지수 스펙트럴 밀도함수를 사용하여 생성시켰다. 경부고속철도차량(K-TGV)중 동력차는 17자유도의 3차원 주행열차로 모형화하였고, 이러한 교량, 궤도불규칙성 및 차량 모형을 이용하여 교량과 차량의 상호작용을 해석할 수 있는 프로그램을 개발하였다. 동적해석을 위한 교량과 차량의 운동방정식은 Lagrange 방정식을 사용하여 유도하였으며, 운동방정식의 수치해석에는 Newmark-β법을 사용하였다. 개발된 프로그램을 이용하여 동력차의 주행에 의한 교량의 시간이력곡선을 구하였으며, 궤도불규칙성의 영향을 분석하였다. 또한 도상의 유무에 따른 교량동적거동의 특성과 함께 열하중의 편심의 영향도 분석하였다.

  • PDF