• Journal of the Korean Statistical Society
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• v.36 no.2
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• pp.321-333
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• 2007

In the proportional hazard model with the beta process prior, the posterior computation with the discrete approximation is considered. The time period of interest is partitioned by small intervals. On each partitioning interval, the likelihood is approximated by that of a binomial experiment and the beta process prior is by a beta distribution. Consequently, the posterior is approximated by that of many independent binomial model with beta priors. The analysis of the leukemia remission data is given as an example. It is illustrated that the length of the partitioning interval affects the posterior and one needs to be careful in choosing it.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.1
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• pp.28-35
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• 2006

Substructure coupling or component mode synthesis may be employed in the solution of dynamic problems for large, flexible structures. The model is partitioned into several subdomains, and a generalized Craig-Bampton representation is derived. In this paper the mode sets (normal modes, constraint modes) is employed for model reduction. A generalized model reduction procedure is described. Vaious reduction methods that use constraint modes is described in detail. As examples, a flexible structure and a 10 DOF damped system are analyzed. Comparison with a conventional reduction method based on a complete model is made via eigenpair and dynamic responses.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.184-186
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• 2002

기존의 색인 기법들은 차원의 수가 증가할수록 검색 성능이 급격히 저하되는 문제를 지니고 있다. 이문제를 극복하기 위하여 CBF 기법이 제안되었다. 그러나 CBF 기법은 데이터 양이 증가함에 따라 검색 성능이 선형적으로 감소하는 문제가 존재한다. 이를 해결하기 위해 다수의 디스크를 수평 분할 방법을 이용하여 디클러스터링(declustering)을 하는 병렬 CBF 기법이 제안되었다. 본 논문에서는 수평 분할 방법을 이용한 병렬 CBF (Parallel CBF) 기법을 삽입시간, 범위 질의 검색시간, k-최근접 질의 검색시간, 데이터의 편중도 측면에서 성능 평가를 수행한다. 아울러, 병렬 CBF 기법을 기존 CBF 기법과 성능 비교를 수행하며, 이를 통해 병렬 CBF 기법이 기존 CBF 기법보다 우수한 검색 성능을 나타냄을 보인다.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.373-375
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• 2000

By DC load flow approximation, we analyzed marginal cost that is the important factor of price signal for network congestion management and expressed as a function of load. In network congestion, a large scale electric network is partitioned into subnetwork to provide a effetive price signal through zonal pricing. We propose a new network partition technique using marginal cost sensitivity with a variety of load consumption.

• The Korean Journal of Applied Statistics
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• v.25 no.3
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• pp.403-413
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• 2012

The modifications suggested in Uhm et al. (2011) are studied using a partly parametric version of Aalen's additive risk model. A follow-up time period is partitioned into intervals, and hazard functions are estimated as a piecewise constant in each interval. A maximum likelihood estimator by iteratively reweighted least squares and variance estimates are suggested based on the model as well as evaluated by simulations using mean square error and a coverage probability, respectively. In conclusion the modifications are needed when there are a small number of uncensored deaths in an interval to estimate the piecewise constant hazard function.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.108-115
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• 2011

This paper describes a new sensor system for mobile robot motion estimation using stereo infrared light sources and a camera. Visibility is being applied to robotic obstacle avoidance path planning and localization. Using simple visibility computation, the environment is partitioned into many visibility sectors. Based on the recognized edges, the sector a robot belongs to is identified and this greatly reduces the search area for localization. Geometric modeling of the vision system enables the estimation of the characteristic pixel position with respect to the robot movement. Finite difference analysis is used for incremental movement and the error sources are investigated. With two characteristic points in the image such as vertices, the robot position and orientation are successfully estimated.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.209-224
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• 2006

This paper presents an optimization model with performance constraints for two kinds of graph elements layout problem. The layout problem is partitioned into finite subproblems by using graph theory and group theory, such that each subproblem overcomes its on-off nature about optimal variable. Furthermore each subproblem is relaxed and the continuity about optimal variable doesn't change. We construct a min-max problem which is locally equivalent to the relaxed subproblem and develop the first order necessary and sufficient conditions for the relaxed subproblem by virtue of the min-max problem and the theories of convex analysis and nonsmooth optimization. The global optimal solution can be obtained through the first order optimality conditions.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.73-80
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• 2001

Barrier is widely used for synchronization in parallel programs. Since the process arrived earlier than others should wait at the barrier, the total processor utilization decreases. In this paper, to find the sources of the barrier waiting time, parallel programs are executed on the various grain sizes through execution-driven simulations. In simulation studies, we found that even if approximately equal amounts of work are distributed to each processor, all processes may not arrive at a barrier at the same time. The reasons are that the different numbers of cache misses and instructions within partitioned grains result in the difference in arrival time of processors at the barrier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.325-333
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• 2000

To predict vibrational energy density and intensity of partitioned complex system structures in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) programs for the plate elements are developed. The flexural, longitudinal and shear waves in plates are formulated and the joint element equations for multi-couped plates are fully developed. Also the wave transmission approach has been introduced to cover the energy transmission and reflection at the joint plate elements. Using the developed PFFEM program the energy density and intensity of the submarine and automobile shape structures are predicted with a harmonic point force at a single frequency.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.4
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• pp.449-455
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• 2014

This paper presents a method for developing a TM (Traversability Map) from a DTM (Digital Terrain Model) collected by remote sensors of autonomous mobile robots. Such a map can be used to plan traversable paths and estimate navigation speed quantitatively in real time for robots capable of performing autonomous tasks over rough terrain environments. The proposed method consists of three parts: a DTM partition module which divides the DTM into equally spaced patches, a terrain information module which extracts the slope and roughness of the partitioned patches using the curve fitting and the fractal-based triangular prism method, and a traversability analysis module which assesses traversability incorporating with extracted terrain information and fuzzy inference to construct a TM. The potential of the proposed method is validated via simulation works over a set of fractal DTMs.