• Journal of Astronomy and Space Sciences
• /
• 제29권3호
• /
• pp.287-293
• /
• 2012

Satellite operating agencies are constantly monitoring conjunctions between satellites and space objects. Two line element (TLE) data, published by the Joint Space Operations Center of the United States Strategic Command, are available as raw data for a preliminary analysis of initial conjunction with a space object without any orbital information. However, there exist several sorts of uncertainties in the TLE data. In this paper, we suggest and analyze a method for estimating the uncertainties in the TLE data through mean, standard deviation of state vector residuals and covariance matrix. Also the estimation results are compared with actual results of orbit determination to validate the estimation method. Characteristics of the state vector residuals depending on the orbital elements are examined by applying the analysis to several satellites in various orbits. Main source of difference between the covariance matrices are also analyzed by comparing the matrices. Particularly, for the Korea Multi-Purpose Satellite-2, we examine the characteristics of the residual variation of state vector and covariance matrix depending on the orbital elements. It is confirmed that a realistic consideration on the space situation of space objects is possible using information from the analysis of mean, standard deviation of the state vector residuals of TLE and covariance matrix.

• 대한수학회보
• /
• 제38권2호
• /
• pp.237-260
• /
• 2001

The approximation properties for $L^2$-projection, Raviart-Thomas projection, and inverse inequality have been derived in 3 dimensional space. h-p-mixed finite element methods for strongly nonlinear second order elliptic problems are proposed and analyzed in 3D. Solvability and convergence of the linearized problem have been shown through duality argument and fixed point argument. The analysis is carried out in detail using Raviart-Thomas-Nedelec spaces as an example.

• Journal of Astronomy and Space Sciences
• /
• 제11권1호
• /
• pp.1-12
• /
• 1994

The structure of the magnetic funnel element in the intermediate polar is considered in terms of an important site for the X-ray absorption and the reemission of the X-ray as the optical light. In this paper the column density and the optical depth vary with the filling factor, which is introduced to characterize the structure of matter in the magnetic funnel element. The results of the energy dependence of the X-ray spectrum and the modulation depth of the X-ray light curve are discussed.

• International Journal of Aeronautical and Space Sciences
• /
• 제7권1호
• /
• pp.91-98
• /
• 2006

The thermomechanical behaviors of SMA thin film actuator and their application are investigated. The numerical algorithm of the 2-D SMA thermomechanical constitutive equation is developed and implemented into the ABAQUS finite element program by using the user defined material (UMAT) subroutine. To verify the numerical algorithm of SMAs, the results are compared with experimental data. For the application of SMA thin film actuator, the methodology to maintain the precise configuration of inflatable membrane structure is demonstrated.

• Journal of Advanced Marine Engineering and Technology
• /
• 제25권2호
• /
• pp.351-356
• /
• 2001

In this paper, a general one-loop control system was assumed as a model system which has a time-delay element connected with a first order-lag element in series. After the corresponding parameter set causing stability limit condition for the model system was obtained by mathematical procedures, their loci on the parameter space was taken according of frequency change,. The parameter set loci of stability limit showed a specific pattern, and particularly the curves on the Kp-Ti parameter space were able to generalized in the form of an exponential formula. These properties were also compared with the results taken from experimental procedures by Nyquist response method and Ziegler & Nichols method on the time domain, and both results were confirmed to be nearly same.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
• /
• pp.75-82
• /
• 2001

A dynamic interaction analysis of an adjacent surface fecundation on a layered half-space is performed in the frequency domain. A semi-analytical approach is employed to reduce the integration range of the wavenumber in the surface fundamental solution for a layered half-space in boundary element (BE) formulations. The present study then adopts a combined boundary and finite element method to analyze the dynamic behavior of a system of flexible surface foundations on an elastic homogeneous and layered half-space. Numerical examples are presented to demonstrate the accuracy of the developed method. The examples show the feasibility of an extended application fur the complicated dynamic interaction of foundations on layered media.

• 한국가구학회지
• /
• 제23권3호
• /
• pp.242-251
• /
• 2012

Geomancy accepts with a pre-requisite that human beings adapt themselves to nature as an organism, because people and environment, bodies and space have the homogeneity which can not be divided by a dichotomy. The homogeneity as a structure alive implies a deep relationship with biorhythm and the change of space, and is regarded as a concept and role significant on the coordination. In other words, applying the element in the geomancy could be interpreted as a work giving a new meaning and spirit on a creation of space and furniture coordination. Harmony and balance shown in design concepts have a relationship with the meaning on Yin-Yang and the Five Elements theory. In addition, the characteristic in each element is suggested as an example applying the concept of geomancy through furniture coordination for each space in the chapter 4.

• 대한전자공학회논문지
• /
• 제17권2호
• /
• pp.23-28
• /
• 1980

C.E.Shannon에 의하여 정보이론의 기초가 확립된 이래 각국언어에 대한 많은 연구가 발표되고 있다. 마찬가지로 한글 element(요소)를 정보공학에 적용하기 위해서는 한글 정보원을 구성하는 모든 element(요소)에 대한 확률이 적용되어야 한다. 본 논문에서는 그간 누락된 Space(공백소)가 포함되었을 때의 엔트로피(entropy)와 리던던시(redundancy)를 고려하였다. 따라서 본 결과는 기존 각종 한글 정보처리장치의 재평가 및 새로운 정보장치의 코-드(code)화에 있어서 수요한 자료로서 사용될 것이다.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
• /
• pp.135-142
• /
• 2000

The adjusting parameter set which enable control systems to locate on stability limit can be derived from theoretical or trial methods for an existing real system. The data from the results are much available to keep a system in the Proper stability condition even to site engineers who are inexperienced in the control system. In this paper, a general one loop control system was adopted for a model system the process of which was assumed to consist of a time-delay element and a first order-lag element in series. After obtaining the corresponding parameter set for the model system by mathematical procedures, their loci on the parameter space was taken according to frequency change. The parameter set loci of stability limit showed unique pattern, and particularity , the curves on the Kg-Ti parameter space were able to be generalized in the form of, an unique exponential formula. These properties were also compared with the results taken from experimental procedures by Nyquist response method and Ziegler & Nichols method on the time domain, and both results were confirmed to be nearly same.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
• /
• pp.73-79
• /
• 1997

It is one of classical problems in the elastic theory to analyze contact stresses between elastic bodies. Concrete pavements under traffic wheel loads can be considered as one of these typical Problems. In the paper, Mindlin plate theory is used to consider the transverse shear effect, 8-node isoparametric plate bending element is adopted in this study, and an elastic plate resting on tensionless elastic half-space is analyzed by finite element method. The Boussineq's solution of elastic half-space is used to evaluate the flexibility of foundation. To obtain the boundary of contact area, the flexibility matrix of foundation is modified after each cycle of analysis iteratively. A Numerical example is presented by using these method.