• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집E
• /
• pp.422-429
• /
• 2001

A two dimensional hierarchical elements are investigated for a use on the incompressible flow computation. The construction of hierarchical elements are explained through the tensor product of 1-D hierarchical functions, and a systematic treatment of essential boundary values has been developed for the degrees of freedom corresponding to higher order terms. The numerical study for the poisson problem showed that the present scheme can increase the convergence and accuracy of finite element solutions, and can be more efficient than the standard first order with many elements. Also, for Stokes and cavity flow cases, solutions from hierarchical elements showed better resolutions and future promises for higher order solutions.

• 한국해양공학회지
• /
• 제15권4호
• /
• pp.108-114
• /
• 2001

Petri nets have been introduced as a powerful analyzing and design tool for the discrete systems such as sequential control systems. However, one of the important problems in its applications is that the model can be analyzed hardly when we deal with large scale systems because of increase of the number of Petri net components. To overcome this problem, some methods for dividing or reducing of Petri net have been suggested. In this paper, an approach for hierarchical expression of Petri net based on Sequential function Chart(SFC) and Bottom Up oriented Mehodology(BUM) is proposed. Especially, some definitions and rules are defined in order to divide and compose sub Petri nets. A measuring tank system will be described as a typical kind of discrete systems and modeled by some sub Petri nets based on the SFC and BUM by the proposed method in this paper.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2001년도 춘계학술대회 논문집
• /
• pp.26-31
• /
• 2001

Petri nets(PN) have been introduced as a poweful analyzing and design tool for the discrete systems such as sequential control systems. However, one of the important problems in its applications is that the model can not be analyzed easily when we deal with large scale systems because of increase of the number of components of the systems. To overcome this problem, some methods for dividing or reducing of PN have been suggested. In this paper, an approach for hierarchical expression of PN based on Sequential Function Chart(SFC) and Bottom Up oriented Mehodology(BUM) is proposed. Especially, some definition and rules are defined in order to divide and compose sub PN. A measuring tank system will be described as a typical kind of discrete systems and modeled by some sub PN based on the SFC and BUM by the proposed method in this paper.

• 한국컴퓨터그래픽스학회논문지
• /
• 제16권4호
• /
• pp.41-50
• /
• 2010

본 논문에서는 계층적 B-spline곡선 (hierarchical B-spline curve)에 대한 새로운 다단계 편집 (multilevel editing)기법을 제안한다. 각 단계 변위함수 (displacement function)의 제어점 (control point)은 이전 단계 곡선위의 노드점 (nodal point)에서 계산되는 Rotation Minimizing Frame (RMF) [1]을 기준으로 표현된다. 이전 단계에서 곡선의 형상이 편집되면 해당노드 점에서 새로운 RMF가 계산되고, 현재 단계에서 변위함수의 제어점들은 새로운 RMF를 기준으로 적용되어, 현재 단계의 곡선은 이전 단계의 곡선에 대한 상대적인 세부 형상을 유지하게 된다. 본 논문에서는 다양한 형태의 곡선에 대한 다단계 편집실험을 통해 제안된 기법의 효율성과 안정성을 입증한다.

• 응용통계연구
• /
• 제12권2호
• /
• pp.405-414
• /
• 1999

양쪽중단(doubly censored)된 지수분포에서 모수와 신뢰도함수를 계층적 베이지안(hierarchical Bayesian)방법을 이용하여 추정하였다. 베이즈 계산은 깁스표본기법(Gibbs sampler)을 이용하고 또한 완전조건부 분포(full conditional distribution)의 정량화 상수를 모르는 경우에는 적합기각방법(adaptive rejection sampling)을 이용하였다. 그리고 실제자료를 이용하여 분석을 하였다.

• Communications for Statistical Applications and Methods
• /
• 제11권1호
• /
• pp.161-168
• /
• 2004

A single-index model is useful in fields which employ multidimensional regression models. Many methods have been developed in parametric and nonparametric approaches. In this paper, posterior inference is considered and a wavelet series is thought of as a function approximated to a true function in the single-index model. The posterior inference needs a prior distribution for each parameter estimated. A prior distribution of each coefficient of the wavelet series is proposed as a hierarchical distribution. A direction $\beta$ is assumed with a unit vector and affects estimate of the true function. Because of the constraint of the direction, a transformation, a spherical polar coordinate $\theta$, of the direction is required. Since the posterior distribution of the direction is unknown, we apply a Metropolis-Hastings algorithm to generate random samples of the direction. Through a Monte Carlo simulation we investigate estimates of the true function and the direction.

• 한국해양공학회지
• /
• 제13권3B호
• /
• pp.106-115
• /
• 1999

Modeling a discrete event system such as a sequential control system is difficult compared with a continuous system. Petri nets have been introduced as an analyzing and design tool for the discrete systems. One of the problems in its applications is that the model can not be analyzed easily in the case of large scale or complicated systems because of increase of the number of components of the system. To overcome this problem, some methods for dividing or reducing Petri nets have been suggested. In this paper, an approach for a hierarchical expression of Petri nets based on Sequential Function Chart(SFC) is proposed. A measuring tank system will be described as a typical kind of discrete systems. The system is modeled by sub Petri nets based on SFC in order to analyze and visualize efficiently about the dynamic behaviors of the system. Some numerical simulations using state equations are performed to prove the validity of the proposed method.

• 한국전자거래학회지
• /
• 제20권4호
• /
• pp.61-76
• /
• 2015

흔히 대용량 텍스트 데이터의 분류를 위한 인덱싱 데이터 구조로서 계층 개념 트리가 활용된다. 본 논문은 개념 계층구조를 자동적으로 구축하기 위해 위키피디아를 이용한 일반성 랭크 기반 기법을 제안한다. 이것의 목적은 위키피디아 문서를 하나의 개념으로 정의하여 이들 간의 계층적 위상관계를 생성하는 것이다. 이를 위해 위키피디아 문서들 간의 링크 개수를 주요 인자로 하여 개념 일반성을 가늠하는 랭킹함수를 고안하였으며, 이를 활용하여 개념 간 확률적 포함관계를 산출함으로써 안정적인 개념 간 계층 구조를 생성한다. 결과적으로 계층적 관계를 담은 개념쌍은 DAG 구조로 시각화 된다. Open Directory Project 계층구조를 사용한 성능 분석을 통해 제안 기법이 기준 기법에 비해 성능이 우수하며 고품질 계층 관계를 안정적으로 추출할 수 있음을 확인하였다.

• 전자공학회논문지B
• /
• 제29B권11호
• /
• pp.73-84
• /
• 1992

In this paper, an algorithm for recovering the 3-D shape from a single shaded image is proposed. In the proposed algorithm, by using the relation between the height and surface gradient (p, q), a set of linear equations is derived from the linearized reflectance function. Then the 3-D surface is recovered by employing the conjugate gradient technique. In order to improve the convergence speed of the solution, we also employ the hierarchical basis function and multiresolution images in the algorithm. A method for determining the regularization parameter, which is determined by trial and error in the conventional approach, is also introduced. In addition, the proposed algorithm attempts to recover the 3-D surface without requiring the boundary conditions, making it suitable for a real-time implementation. Simulation results for real image as well as synthetic image are provided to demonstrate the performance of the proposed algorithm.

• Journal of the Korean Statistical Society
• /
• 제34권3호
• /
• pp.209-218
• /
• 2005

In response surfaces analysis, we often proceed by supposing that, over a limited region of factor space, a polynomial of only first or second degree might adequately approximate the true function. To find the best subset model, all possible quadratic regressions for response surfaces can be very valuable to get optimum solutions under some reasonable experimentations. However, there is a very hard computational burden to get all possible quadratic regressions. In practice, it is sufficient to consider only hierarchical models. In this paper, we propose an algorithm to get all possible hierarchical quadratic regressions for fitting response surfaces.