• 제목/요약/키워드: moment problems

검색결과 422건 처리시간 0.025초

China's Debt Woes: Not Yet a "Lehman Moment"

  • Sharma, Shalendra D.
    • East Asian Economic Review
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    • 제19권1호
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    • pp.99-114
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    • 2015
  • What explains the sharp increase in the Chinese economy's indebtedness, in particular the China's onshore corporate debt? Has the overall debt burden reached a threshold where it poses a systemic risk, thereby making the economy vulnerable to a "Lehman Moment" - with disorderly unwinding of the private sector and sovereign debt? What are the short and longer term implications of China's growing debt problems on domestic economic growth and the broader global political economy? What has Beijing done to ameliorate the problem, how effective were its efforts, and what must it do to deal with this problem?

Moments of a Class of Internally Truncated Normal Distributions

  • Kim, Hea-Jung
    • Communications for Statistical Applications and Methods
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    • 제14권3호
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    • pp.679-686
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    • 2007
  • Moment expressions are derived for the internally truncated normal distributions commonly applied to screening and constrained problems. They are obtained from using a recursive relation between the moments of the normal distribution whose distribution is truncated in its internal part. Closed form formulae for the moments can be presented up to $N^{th}$ order under the internally truncated case. Necessary theories and two applications are provided.

Aspects on Nonuniqueness and Instability Inherent in Inverse Scattering Problems

  • Kim, Se-Yun
    • Journal of electromagnetic engineering and science
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    • 제3권2호
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    • pp.133-139
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    • 2003
  • The nonuniqueness of a mathematically rigorous solution to 2-dimensional inverse scattering problems is explained in a limiting view of the numerical calculations based on the spectral-domain moment method. It is illustrated that its theoretical uniqueness cannot be assured even by performing additional measurements of the scattered fields not only along multiple lines but also with angular/frequency-diversities. In a real situation, however, computational error and measurement noise are inevitable. Those limitations render it meaningless to controvert the existence of a theoretically rigorous solution. Hence the most practical issue is how to remedy the instability of its practically approximate solution.

Steepest Descent Method를 이용한 정전계 문제의 해석 (On the Analysis of Electrostatic Problems Using a Steepest Descent Method)

  • 안지용;정구철;김정기
    • 한국통신학회논문지
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    • 제11권6호
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    • pp.396-401
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    • 1986
  • Steepest Descent Method를 정전계 문제의 해석에 적용하였다. 반복법과 moment method와 같은 direct method와의 차이점을 기술하였다. 반복법을 이용하여 정확한 해에 단조적으로 수렴하며 대형 system의 해석에 적합함을 보였다. 정전계 문제에 대해서 해석한 수치결과를 제시하였으며 moment solution과 잘 일치하고 있음을 보였다.

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원통형 쉘의 휨 좌굴 거동에 대한 연구 (A Study on the Bending Buckling Behavior of Circular Cylindrical Shells)

  • 정진환;김성도;하지명
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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    • pp.208-215
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    • 1998
  • A stability problems of isotropic shells under pure bending is investigated based on the classical shells theory. The governing equations of stability problem presented by Donnell and Love, are developed and the solutions for the cylindrical shells are obtained by using Galerkin method. Bending moment is applied at the ends of the cylindrical shell as a from of distributed load in the shape of sine curve. For the isotropic materials, the result of the general purpose structural analysis program based on the finite element method are compared with the critical moment obtained from the classical shell theories. The critical loads for the cylindrical shells with various geometry can not be evaluated with a simple equation. However, accurate solutions for the stability problems of cylindrical shells can be obtained through the equilibrium equation developed in the study.

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모우먼트법에 의한 안테나의 전류분포와 입력임피던스의 해석 (The Analysis of the Current Distribution and Input Impedance of an Antenna by the Moment Method)

  • 양인응;이상설;오승엽
    • 대한전자공학회논문지
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    • 제11권4호
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    • pp.30-38
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    • 1974
  • Moment법에 의하여 임의형상으로 굴곡된 선형 안테나의 전류분포와 임의의 급전점에 대한 인력임피던스를 구하는 방법을 제시하고 그 이론을 정강파형으로 굴곡된 안테나에 적용하여 전류분포와 입력임피던스를 구했다. 실험결과가 그의 타당성을 뒷 받침하고 있어 다른 형태의 안테나 문제를 분석하는데 널리 이용 될 수 있다.

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조합기법을 이용한 다중생체신호의 특징추출에 의한 실시간 인증시스템 개발 (Development of Real-Time Verification System by Features Extraction of Multimodal Biometrics Using Hybrid Method)

  • 조용현
    • 한국산업융합학회 논문집
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    • 제9권4호
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    • pp.263-268
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    • 2006
  • This paper presents a real-time verification system by extracting a features of multimodal biometrics using hybrid method, which is combined the moment balance and the independent component analysis(ICA). The moment balance is applied to reduce the computation loads by extracting the validity signal due to exclude the needless backgrounds of multimodal biometrics. ICA is also applied to increase the verification performance by removing the overlapping signals due to extract the statistically independent basis of signals. Multimodal biometrics are used both the faces and the fingerprints which are acquired by Web camera and acquisition device, respectively. The proposed system has been applied to the fusion problems of 48 faces and 48 fingerprints(24 persons * 2 scenes) of 320*240 pixels, respectively. The experimental results show that the proposed system has a superior verification performances(speed, rate).

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V/W형 왕복동 공기압측기의 평형에 관한 연구 (A Study on the Balancing of V/W-type Reciprocating Air Compressor)

  • 김형진;김성춘;김정만;김의간
    • 한국소음진동공학회논문집
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    • 제14권1호
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    • pp.24-31
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    • 2004
  • Recently, as the marine compressor power is increased, vibration problems on the marine vessel with V/W type reciprocating compressor have been occurred. A research on the balancing of marine V/W type reciprocating compressor has hardly been reported though a number of researches on the balancing of rotating machinery have been conducted. As a V/W type compressor has high capacity with long stroke, compact size and high center of gravity, It is easy to have a vibration problem by a little bit unbalanced force and moment. In this study, calculation methods for balance weight of the V/W type reciprocating compressors, which have different piston weight and asymmetry structure, are formulated. And their reliability were verified by comparing calculated balance weight with the experimental results of the real marine V/W type reciprocating compressors.

Attitude Control of Agile Spacecraft Using Momentum Exchange Devices

  • Lee, Hyun-Jae;Cho, Shin-Je;Bang, Hyo-Choong
    • International Journal of Aeronautical and Space Sciences
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    • 제7권2호
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    • pp.14-25
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    • 2006
  • This paper is focused on designing an implementable control law to perform spacecraft various missions using momentum exchange devices such as reaction wheels(RWs) and control moment gyros(CMGs). A compact equation of motion of a spacecraft installed with various momentum exchange devices is derived in this paper. A hybrid control law is proposed for precision attitude control of agile spacecraft. The control law proposed in this paper allocates control torque to the CMGs and the RWs adequately to satisfy the precision attitude control and large angle maneuver simultaneously. The saturation problem of reaction wheels and the singularity problem of control moment gyros are considered. The problems are successfully resolved by using the proposed hybrid closed loop control law. Finally, the proposed hybrid control law is demonstrated by numerical simulations.

Probabilistic computation of the structural performance of moment resisting steel frames

  • Ceribasi, Seyit
    • Steel and Composite Structures
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    • 제24권3호
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    • pp.369-382
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    • 2017
  • This study investigates the reliability of the performance levels of moment resisting steel frames subjected to lateral loads such as wind and earthquake. The reliability assessment has been performed with respect to three performance levels: serviceability, damageability, and ultimate limit states. A four-story moment resisting frame is used as a typical example. In the reliability assessment the uncertainties in the loadings and in the capacity of the frame have been considered. The wind and earthquake loads are assumed to have lognormal distribution, and the frame resistance is assumed to have a normal distribution. In order to obtain an appropriate limit state function a linear relation between the loading and the deflection is formed. For the reliability analysis an algorithm has been developed for determination of limit state functions and iterations of the first order reliability method (FORM) procedure. By the method presented herein the multivariable analysis of a complicated reliability problem is reduced to an S-R problem. The procedure for iterations has been tested by a known problem for the purpose of avoiding convergence problems. The reliability indices for many cases have been obtained and also the effects of the coefficient of variation of load and resistance have been investigated.