• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.624-630
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• 2007

The dynamic window approach(DWA) is a well known technique for reactive collision avoidance. It shows safe and efficient performance in real-world experiments. However, a robot can get stuck in local minima because no information about the connectivity of the free space is used to determine the motion. The global DWA can solve this problem of local minima by adding a navigation function. Even with the global DWA, it is still difficult for a robot to execute an abrupt change in its direction, for example, entering from the corridor to a doorway. This paper proposes a modified global DWA using the included angles of waypoints extracted from an optimal path. This scheme enables the robot to decelerate in advance before turning into the doorway. Therefore the robot can reach the goal position more safely and efficiently at high speeds.

• 한국해양학회지
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• v.2 no.1_2
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• pp.34-41
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• 1967

1. 아한대수의 전형적 지표종인 Sagitta elegans는 동해에서 대마난류축을 제외 하고는 전역에 균등히 분포하고 있으며, 표층 및 수직채집상으로 보아 감포동남방 57리 지점의 다수출현은 잠류남하하는 한류 및 저층냉수의 용승에 기인함을 실증하고 있으며, 한류의 이동은 외양에서는 축산원해에서 표면 이하로 잠류남하하는 것으로 본다. 2. Sagitta bedoti는 전역에 걸쳐, 난류 및 중간수역에서 광범하게 분포되어 있으며 남해측에는 난류역을 피하고 제주서남방 및 서측에 풍부함으로서 냉수역 및 중간수대의 지표종이 되고 있다. 한편 난류성인 Sagitta enflata, Sagitta minima 와 Sagitta serratodentataa, Pterosagitta drace 등은 서해를 제외하고는 광범한 분포상을 시현하고 있으나 특히 남해에서는 난류주류역에 우세하였다. 생태상으로 보아 Sagatta enflata는 순표층성인데 반하여 Sagatta minima는 중층성으로서 난류의 강약 및 유동을 지표하는 종류로서 가치가 크다고 본다. 3. Sagitta crassa는 서해수의 지표종이며 동해 및 제주서남방에 대량출현하여 저철연안수의 특유한 지표역으 맡고 있다.

• Animal Systematics, Evolution and Diversity
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• v.29 no.3
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• pp.259-266
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• 2013

A newly recorded aorid species, Paragrandidierella minima Ariyama, 2002, from Korean waters is reported with a description and illustrations, and its generic features are considered. This species is characterized by the carpochelate gnathopod 1 in matured male, the posterodistal protrusion on peduncle 5 of antenna 2, the absence of the apical spine on inner plate of maxilliped, the minute apical projection on inner lobe of lower lip, the acute posteroproximal extension on the basis of each pereopod 5 and 6, the shape of uropods and telson, and the large inter-ramal process of uropod 1. This is the first report of the genus Paragrandidierella from Korea.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.278-278
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• 2000

In this paper, we introduce a new genetic reordering operator based on the concept of schema to solve optimization problems such as the Traveling Salesman Problem(TSP) and maximizing or minimizing functions. In particular, because TSP is a well-known combinational optimization problem andbelongs to a NP-complete problem, there is huge solution space to be searched. For robustness to local minima, the operator separates selected strings into two parts to reduce the destructive probability of good building blocks. And it applies inversion to the schema part to prevent the premature convergence. At the same time, it searches new spaces of solutions. Additionally, the non-schema part is applied to inversion for robustness to local minima. By doing so, we can preserve diversity of the distributions in population and make GA be adaptive to the dynamic environment.

• Korean Management Science Review
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• v.24 no.2
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• pp.115-126
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• 2007

Weekly minima of daily log returns of Korean composite stock price index 200 and its five industry-based business divisions over the period from January 1990 to December 2005 are fitted using two block-based extreme distributions: Generalized Extreme Value(GEV) and Generalized Logistic(GLO). Parameters are estimated using the probability weighted moments. Applicability of two distributions is investigated using the Monte Carlo simulation based empirical p-values of Anderson Darling test. Our empirical results indicate that both the GLO and GEV models seem to be comparably applicable to the weekly minima. These findings are against the evidences in Gettinby et al.[7], who claimed that the GEV model was not valid in many cases, and supported the significant superiority of the GLO model.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.8
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• pp.50-59
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• 1996

In this paper, a new hierarchical motion estiamtion scheme using the wavelet transformed multi-resolution image layers is proposed. Compared with the full search motion estimation method, the existing hierarchical methods remarkably reduce the amount of the computation but their efficiencies are depreciated by the local minima problem. In order to solve the local minima problem, the multi-resolution image layers are composed using the wavelet transform and the number of layers participated in the motion estimation for a block is determined by considering of its low band energy and higher band energy on the first wavelet transformed layer. The ratio between higher band energy and low band energy of each block is evaluated and in the case of the blocks which include relatively large higher band energy, the motion estimation is carried out in the high resolution layer. Otherwise, all layers are used. The final motion vectors are obtained in the first wavelet transformed layer. So less bits for motion vectors are transmitted, and the decomposition of received image using inverse wavelet transform decreases the blocking effect.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.378-383
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• 1999

Ab initio calculation is performed to estimate the substituent effects for Para-substituted pyridines. Electrostatic potentials are obtained from ab initio molecular orbital wavefunctions of optimized structures for substituted pyridines. Electrostatic potentials are computed to be minimum at nitrogen atom of pyridines. The potential minima are good correlated with the substituent constants, ${\sigma}_p$ and with the ${\Delta}pKa$. It is shown that the electrostatic potential minima can be used as a measure of substituent effects.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.232-235
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• 2000

In this paper, we introduce a new genetic reordering operator based on the concept of schema to solve the Traveling Salesman Problem(TSP). Because TSP is a well-known combinatorial optimization problem and belongs to a NP-complete problem, there is a huge solution space to be searched. For robustness to local minima, the operator separates selected strings into two parts to reduce the destructive probability of good building blocks. And it applies inversion to the schema part to prevent the premature convergence. At the same time, it searches new spaces of solutions. In addition, we have the non-schema part to be applied to inversion as well as for robustness to local minima. By doing so, we can preserve diversity of the distributions in population and make GA be adaptive to the dynamic environment.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.482-485
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• 2000

A modified watershed transform is proposed which is context-free marker-controlled and minima imposition-free to reduce the over-segmentation and to speedup the transform. In contrast to the conventional methods in which a priori knowledge, such as flat zones, zones of homogeneous texture, and morphological distance, is required for marker extraction, context-free marker extraction is proposed by using the attention operator based on the GST (generalized symmetry transform). By using the context-free marker, the proposed watershed transform exploit marker-constrained labeling to speedup the computation and to reduce the over-segmentation by eliminating the unnecessary geodesic reconstruction such as the minima imposition and thereby eliminating the necessity of the post-processing of region merging. The simulation results show that the proposed method can extract context-free markers inside the objects from the complex background that includes multiple objects and efficiently reduces over-segmentation and computation time.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.80-86
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• 2002

A neural network structure which is able to perform the operations of analog addition and linear equation is proposed. The network employs Hopfkeld's model of a neuron with the connection elements specified on the basis of an analysis of the energy function. The analog addition network and linear equation network are designed by using Hopfield's A/D converter and linear programming respectively. Simulation using Pspice has shown convergence predominently to the correct global minima.