• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.154-161
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• 1997

This paper presents the method to eliminate the constraint reaction in the Lagrange multiplier form equation of motion by using a generalized coordinate driveder from the velocity constraint equation. This method introduces a matrix method by considering the m dimensional space spanned by the rows of the constraint jacobian matrix. The orthogonal vectors defining the constraint manifold are projected to null vectors by the tangential vectors defined on the constraint manifold. Therefore the orthogonal projection matrix is defined by the tangential vectors. For correcting the generalized position coordinate, the optimization problem is formulated. And this correction process is analyzed by the quasi Newton method. Finally this method is verified through 3 dimensional vehicle model.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2705-2708
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• 2003

In this paper, we propose a method that applies matrix decomposition technique to the connection of actuator capabilities of each robot to object acceleration limits for multiple cooperative robot systems. The robot systems under consideration are composed of several robot manipulators and each robot contacts a single object to carry the object while satisfying the constraints described in kinematics as well as dynamics. By manipulating kinematic and dynamic equations of both robots and objects, we at first derive a matrix relating joint torques with object acceleration, manipulate the null space of the matrix, and then we decompose the matrix into three parts representing indeterminancy, connectivity, and redundancy. With the decomposed matrix we derive the boundaries of object accelerations from given joint actuators. To show the validity of the proposed method some examples are given in which the results can be expected by intuitive observation.

• ETRI Journal
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• v.33 no.6
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• pp.831-840
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• 2011

This paper focuses on codebook-based precoding for space-division multiple access/orthogonal frequency-division multiple access (SDMA-OFDMA) systems aiming to guarantee high throughput for their users as well as to mitigate interference to fixed satellite service (FSS). A systematic design of SDMA codebook for subband-based OFDMA is proposed, which forms multiple orthogonal beams with common spatial null in the direction of a victim FSS earth station (ES). The design enables both transmitter and receiver to independently construct identical codebook by sharing only on the direction angle of an FSS ES, which takes fewer overhead bits than Gram-Schmidt process, a general method satisfying our design criterion. A system-level throughput evaluation shows that the proposed precoding provides superior performance over existing spectrum sharing method, that is, subband deactivation. The spectrum sharing analysis shows that the proposed precoding, even with an estimation error of the direction angles of an FSS ES, causes lower interference than existing precoding, knockdown precoding.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.67-75
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• 2014

A full-scale static test for a composite structure small aircraft (KC-100) was conducted in the KARI. The test includes 15 full-scale test and 7 local test conditions. Test requirements with test schedule, test article with dummy structures, test load generation, test system, and equipment are introduced for the test. Test load data of the 1st test condition(U1) was analyzed to evaluate an accuracy of load control for the test. The analysis results show that load data obtained during test were within tolerance of Static Null Pacing Error(SNPE) and the error value of load control was 8.6N. The error of load controls for the full-scale static test using dozens of actuators was calculated by a method suggested by authors. Test data for all other test conditions is also shown in this paper. Finally, reactions measured from restraint system of the U1 test condition show that the reaction changes as load increment. The factors which may change the change of reactions for a full-scale static test are introduced in this study.

• Journal of the Korean Operations Research and Management Science Society
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• v.12 no.1
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• pp.19-26
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• 1987

In analyzing time series, estimating the level or the current mean of the process plays an important role in understanding its structure and in being able to make forecasts. The studies the class of time series models where the level of the process is assumed to follow a random walk and the deviation from the level follow an ARMA process. The estimation and forecasting problem in a Bayesian framework and uses the Kalman filter to obtain forecasts based on estimates of level. In the analysis of time series, we usually make the assumption that the time series is generated by one model. However, in many situations the time series undergoes a structural change at one point in time. For example there may be a change in the distribution of random variables or in parameter values. Another example occurs when the level of the process changes abruptly at one period. In order to study such problems, the assumption that level follows a random walk process is relaxed to include a major level change at a particular point in time. The major level change is detected by examining the likelihood raio under a null hypothesis of no change and an alternative hypothesis of a major level change. The author proposes a method for estimation the size of the level change by adding one state variable to the state space model of the original Kalman filter. Detailed theoretical and numerical results are obtained for th first order autoregressive process wirth level changes.