• International Journal of Control, Automation, and Systems
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• 제5권3호
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• pp.251-268
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• 2007

A Gaussian sum filter (GSF) is proposed in this paper on simultaneous localization and mapping (SLAM) for mobile robot navigation. In particular, the SLAM problem is tackled here for cases when only bearing measurements are available. Within the stochastic mapping framework using an extended Kalman filter (EKF), a Gaussian probability density function (pdf) is assumed to describe the range-and-bearing sensor noise. In the case of a bearing-only sensor, a sum of weighted Gaussians is used to represent the non-Gaussian robot-landmark range uncertainty, resulting in a bank of EKFs for estimation of the robot and landmark locations. In our approach, the Gaussian parameters are designed on the basis of minimizing the representation error. The computational complexity of the GSF is reduced by applying the sequential probability ratio test (SPRT) to remove under-performing EKFs. Extensive experimental results are included to demonstrate the effectiveness and efficiency of the proposed techniques.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.732-734
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• 2005

현재의 서비스들은 각기 독립적으로 운영되고 있으며 서비스레벨 측면에서 상호 동작은 없다. 이는 각 인터넷서비스의 특성이 다양하고, 개별적인 특성을 가지고 있음 의미한다. 그러나 앞으로 다가올 NGN환경에서 현재의 다양한 네트워크 기반으로 동작하는 각기 독립적으로 동작하는 응용들 사이에서 상호연계성을 갖는 통합된 서비스 기능이 필요하게 된다. 이를 위해서는 각 응용들이 같이 사용할 수 있는 응용 측면에서의 통합과 기능을 수행하는 함수가 필요하다. 또한 NGN에서는 현재의 E-business에 웹 서비스 등의 기능과 융합된 고부가가치의 응용이 필요하다. 본 논문에서는 이러한 여러 이종간 서비스의 가능한 서비스 융합 방법을 보인다

• 정보처리학회논문지D
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• 제8D권6호
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• pp.843-852
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• 2001

소프트웨어의 오류에 대한 통계를 보면 구현단계보다 분석과 설계 단계에 더 중요하고 많은 오류가 유입된다. 따라서 소프트웨어의 분석 및 설계 작업의 결과인 디자인 모델이 요구에 맞게 설계되었는지, 또는 구조적으로 적합한지 잘 점검할 필요가 있다. 이 논문에서는 객체지향 설계 방법으로 사용되고 있는 UML로 표현된 설계 모델을 효과적으로 테스트할 수 있는 방법에 대해 논의하였다. UML 모델을 이루는 각 요소들에 대한 제약조건을 OCL(Object Constraint Language)로 기술하고 카테고리 분할 방법을 이용하여 UML모델을 테스트하기 위한 데이터를 생성하는 방법을 제안하였다. 생성된 테스트 데이터를 이용하여 객체지향으로 설계된 모델뿐만 아니라 개발된 시스템의 기능 테스트를 수행할 수 있다.

• 로봇학회논문지
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• 제12권1호
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• pp.33-41
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• 2017

We present a region-based approach for accurate pose estimation of small mechanical components. Our algorithm consists of two key phases: Multi-view object co-segmentation and pose estimation. In the first phase, we explain an automatic method to extract binary masks of a target object captured from multiple viewpoints. For initialization, we assume the target object is bounded by the convex volume of interest defined by a few user inputs. The co-segmented target object shares the same geometric representation in space, and has distinctive color models from those of the backgrounds. In the second phase, we retrieve a 3D model instance with correct upright orientation, and estimate a relative pose of the object observed from images. Our energy function, combining region and boundary terms for the proposed measures, maximizes the overlapping regions and boundaries between the multi-view co-segmentations and projected masks of the reference model. Based on high-quality co-segmentations consistent across all different viewpoints, our final results are accurate model indices and pose parameters of the extracted object. We demonstrate the effectiveness of the proposed method using various examples.

• 한국해안해양공학회지
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• 제7권1호
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• pp.116-125
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• 1995

파하중과 해류하중을 받는 단일 자유도계를 동적 해석하여 비선형 거동을 나타냄을 보이고 고차의 비선형 전이함수를 포함한 모델을 적용하여 그 비선형 차수를 알아낸다. 먼저 구조물에 단일 정현파, 두 파의 합성파 그리고 불규칙파 하중을 차례로 가하면서 각 하중조건마다 세가지 비선형 요인의 효과를 조사한다. 이로부터 단일 자유도계의 공진주파수에서 파의 에너지는 존재하지 않지만 비선형 요인에 의해 응답 성분이 나타남을 보인다. 다음으로 Volterra 급수에 근거한 고차 전이함수(higher order transfer function)모델을 적용하여 유연한 단일 자유도계의 비선형 거동이 성공적으로 모델화됨을 보이며 또한 비선형성이 2차나 3차로 명백히 나타남을 보인다.

• 한국실내디자인학회논문집
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• 제18권1호
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• pp.64-71
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• 2009

The modern society is rapidly changing through the development of computer network technology. By generation a collapse of boundaries between may important social institutions, computer networking has affected culture, economy and the physical environment. Because of this, people face a switchover from a simple society, to a compound society. It will also increase the diversity if society's demand, though, and experience. This change is not an exception in the exhibition space. People are more interested in civilized pastimes and also demand diverse thinking. So as a necessary consequence, the function of museum space Is offended and that there are various attempt to increase information and demand of that space. The purpose of this study is try to find a solution a countermeasure of modern society's mobile situation. Researchers analyzed structural qualities of Hyper-text; non-boundary, interaction and nonlinear and deduce nine kinds of methods to apply in space. Also, Researchers looked at the examples in museum space and derived like this expression way; dynamics, mobility, a non-materiality, continuity, complexity from analysis of expression way.

• 대한기계학회논문집A
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• 제26권10호
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• pp.2150-2158
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• 2002

A recent research and development has the requirement for the optimization to shorten design time of modified or new product model and to obtain more precise engineering solution. General optimization problem must consider many conflicted objective functions simultaneously. Multi-objective optimization treats the multiple objective functions and constraints with design change. But, real engineering problem doesn't describe accurate constraint and objective function owing to the limit of representation. Therefore this study applies variance analysis on the basis of structure analysis and DOE to the vertical roller mill fur portland cement and proposed statistical design model to evaluate the effect of structural modification with design change by performing practical multi-objective optimization considering mass, stress and deflection.

• 한국콘텐츠학회논문지
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• 제9권6호
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• pp.45-52
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• 2009

최근 제조업에서 제품 설계를 지원하는 디지털 전문가 시스템을 개발하는 사례가 일어나고 있다. 이 시스템은 제조업에서 엔지니어가 프로세스를 통제하고, 생산관리와 시스템 관리 등을 위하여 사용되고 있다. 본 논문에서는 전문가 시스템을 구축하기 위한 온톨로지 기반의 추론 엔진 개발에 대하여 논한다. 전문가 시스템은 한국어를 지원하고 다양한 기능을 가지며, 그래픽한 온톨로지 맵 인터페이스와 퍼지 룰 기능 정의 등의 기능을 갖도록 하였다. 또한, 온톨로지 맵 구축과 온톨로지 기반의 퍼지 추론 방법에 대하여 지식을 표현하는 방법에 대하여 설명한다.

• Structural Engineering and Mechanics
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• 제55권6호
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• pp.1241-1260
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• 2015

Any rational approach to define the configuration and size of viscous fluid dampers in a structure should be based on the dynamic properties of the system with the dampers. In this paper we propose an alternative representation of the complex eigenvalues of multi degree of freedom systems with dampers to calculate new equivalent natural frequencies. Analytical expressions for the dynamic properties of a two-story building model with a linear viscous damper in the first floor (i.e. with a non-proportional damping matrix) are derived. The formulas permit to obtain the equivalent damping ratios and equivalent natural frequencies for all the modes as a function of the mass, stiffness and damping coefficient for underdamped and overdamped systems. It is shown that the commonly used formula to define the equivalent natural frequency is not applicable for this type of system and for others where the damping matrix is not proportional to the mass matrix, stiffness matrix or both. Moreover, the new expressions for the equivalent natural frequencies expose a novel phenomenon; the use of viscous fluid dampers can modify the vibration frequencies of the structure. The significance of the new equivalent natural frequencies is expounded by means of a simulated free vibration test. The proposed approach may offer a new perspective to study the effect of viscous dampers on the dynamic properties of a structure.

• Structural Engineering and Mechanics
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• 제29권3호
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• pp.289-300
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• 2008

The use of metric trial functions to represent the real stress field in what is called the unsymmetric finite element formulation is an effective way to improve predictions from distorted finite elements. This approach works surprisingly well because the use of parametric functions for the test functions satisfies the continuity conditions while the use of metric (Cartesian) shape functions for the trial functions attempts to ensure that the stress representation during finite element computation can retrieve in a best-fit manner, the actual variation of stress in the metric space. However, the issue of how to handle situations where there is locking along with mesh distortion has never been addressed. In this paper, we show that the use of a consistent definition of the constrained strain field in the metric space can ensure a lock-free solution even when there is mesh distortion. The three-noded Timoshenko beam element is used to illustrate the principles. Some significant conclusions are drawn regarding the optimal strategy for finite element modelling where distortion effects and field-consistency requirements have to be reconciled simultaneously.