• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.50-57
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• 2003

In the paper, the design and evaluation of a helicopter trajectory tracking controller are presented. The control algorithm is implemented using the feedback linearization technique and the two time-scale separation architecture. In addition, and on-line adaptive architecture that employs a neural network compensating the model inversion error caused by the deficiency of full knowledge of helicopter dynamic is applied to augment the attitude control system. Trajectory tracking performance of the control system in evaluated using modified TMAN simulation program representing as Apache helicopter. It is show that the on-line neural network in an adaptive control architecture is very effective in dealing with the performance depreciation problem of the trajectory tracking control caused by insufficient information of dynamics.

• The KIPS Transactions:PartD
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• v.13D no.3 s.106
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• pp.325-336
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• 2006

For supporting LBS service, recent studies on spatial network databases (SNDB) have been done actively. In order to gain good performance on query processing in SNDB, we, in this paper. design efficient storage and index structures for spatial network data, point of interests (POIs), and moving objects on spatial networks. First, we design a spatial network file organization for maintaining the spatial network data itself consisting of both node and edges. Secondly, we design a POI storage and index structure which is used for gaining fast accesses to POIs, like restaurant, hotel, and gas station. Thirdly, we design a signature-based storage and index structure for efficiently maintaining past, current, and expected future trajectory information of moving objects. Finally, we show that the storage and index structures designed in this paper outperform the existing storage structures for spatial networks as well as the conventional trajectory index structures for moving objects.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.2
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• pp.23-28
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• 2008

Purpose: To develop the 2~8X zoom beam expander for the 1064 nm laser source. Methods: After developing the program by which the initial design values of 3-component zoom tracks can be quickly obtaind, we design and develop the zoom beam expander by applying this program and the commercial program of Sigma 2000. Results: In this study, we could develop the program by which the initial design values of zoom tracks can be quickly obtaind, and by applying this program and the commercial program of Sigma 2000 we could design and develop the zoom beam expander for 1064 nm which is able to zoom from 2${\times}$ to 8${\times}$. The developed zoom beam expander has an efficient diameter of the incidence side of 8 mm, an efficient diameter of the exit side of 32 mm, and a capacity with the finite ray aberration within 0.0001rad. Because the overall length (OAL) is restricted between 125 mm and 135 mm, the change of the whole barrel length which is caused by variations of the zoom driving becomes to be within 10 mm. Conclusions: we could develop the program by which the initial design values of zoom tracks can be quickly obtaind, and by applying this program we could design and develop the zoom beam expander for 1064 nm which is able to zoom from 2${\times}$ to 8${\times}$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.8
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• pp.719-731
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• 1991

This paper introduces a relatively simple computer simulation method for analyzing trajectory of electron beam in cylindrical electrode of the CRT, which outputs the cutoff voltag, beam current, spot size and plots out the trajectory, rom the input data on physical construction and applied voltages of electron gun. In order to improve computing speed in obtaining potential distibution, the authors have ivided the space into seveal setos and allocated different mesh sizes epending on the acuracy required to each sector and applied the finite difference method in calculation. The plot of trajectoy obtained from the simulation provided useful insight into the focusing mechanism of the CRT. The computed and measured result including beam curent. spot sizs and cutoff voltages for several model guns have ageed within eperimental error. The simulation program enables the designer to compare the effects of varied electrode shpe without the epense of building an actual gun and may be appli in esigning and implementing the electron gun assemply.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1167-1168
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• 2013

• Journal of the korean Society of Automotive Engineers
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• v.26 no.2
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• pp.10-16
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• 2004

일반적으로 기구라 함은 어떤 한정된 상대운동을 할 수 있도록 각종 Joint로 연결된 여러 강체들의 조합을 의미한다. 또한 기구는 많은 기계적 장치들의 가장 중요한 설계인자중의 하나라 할 수 있는 기하학적 특성들을 구현할 수 있도록 구성되어지며, 그 기하학적 특성은 주로 주 관심 대상인 강체의 기준 강체에 대한 궤적 특성이라 할 수 있겠다.(중략)

• Proceedings of the Korean Magnestics Society Conference
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• 2012.11a
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• pp.113-115
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• 2012

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.201-204
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• 2008

The mobile robot is known as a nonlinear system with constraints. The general tracking controller for the mobile platform has been divided into the kinematic and the dynamic controller. The reason of dividing controller is the constraints. We can get some information through some numerical experiments. When the reference linear and angular velocity were given, the stability of mobile robot without the kinematic controller depend on the start point of reference cart. Therefore this paper composed of two controller for solving tracking problem. The main controller is the dynamic controller which used generally such as the PID controller. And this paper adopts the auxiliary controller in order to compensate the difference of initial point between the reference cart and a mobile robot. Finally, the numerical experiment is performed in order to show the validity of our method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1828-1834
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• 2004

With the rapid development of wireless communications and mobile technologies, requirements of various services based on moving objects like location-based services and mobile applications services have been increased. In this paper, we propose an index structure which can improve the performance on trajectory-based query especially, one of the various query types for moving objects in mobile applications. It maintains link table(L-Table) to obtain good efficiency on retrieval and insertion performance of the existing TB(Trajectory Bundle)-tree proposed for trajectory-based query of moving objects. The L-Table contains page number in disk and memory pointers pointing the leaf node with the first and last line segment of moving objects in order to directly access preceding node. In addition, we design to reside a part of whole index in main memory by preserving a fixed size of buffer in case of being restricted by available main memory. Finally, experimental results with various data sets show that the proposed technique is superior to the existing index structures with respect to insertion and trajectory-based query.

• Journal of Korea Spatial Information System Society
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• v.7 no.2 s.14
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• pp.67-79
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• 2005

For tracing tag locations, the trajectories should be modeled and indexed in a radio frequency identification (RFID) system. The trajectory of a tag is represented as a line that connects two spatiotemporal locations captured when the tag enters and leaves the vicinity of a reader. If a tag enters but does not leave a reader, its trajectory is represented only as a point captured at entry. Because the information that a tag stays in a reader is missing from the trajectory represented only as a point, it is impossible to find the tag that remains in a reader. To solve this problem we propose the data model in which trajectories are defined as intervals and new index scheme called the Interval R-tree. We also propose new insert and split algorithms to enable efficient query processing. We evaluate the performance of the proposed index scheme and compare it with the R-tree and the R*-tree. Our experiments show that the new index scheme outperforms the other two in processing queries of tags on various datasets.