• 대한기계학회논문집A
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• 제25권1호
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• pp.1-10
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• 2001

As computer power is increased, refined finite element models are employed for structural analysis. However, it is difficult and expensive to use refined models in the design stage. The refined models especially cause problems in the preliminary design where the design is frequently changed. Therefore, simplified models are needed. The simplification process is regarded as an empirical technique. Simplified and equivalent finite element model of a structure has been studied and used in the preliminary design. A general approach to establish the simplified and equivalent model is presented. The generated simple model has satisfactory correlation with the corresponding refined finite element model. An optimization method, the Goal Programming algorithm is used to make the simple model. The simplified model is used for the design change and the changed design is recovered onto the original design. The presented method was verified with three examples.

• 한국인터넷방송통신학회논문지
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• 제16권4호
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• pp.147-152
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• 2016

데이터에 내포되어 있는 주요 정보나 지식을 추출해 내는 기계학습 방법에서 주요 이슈의 하나는 지식 표현 방식이다. 여러 가지 구조로 표현될 수 있는 지식을 모델이라고 부른다. 모델에는 그 내부 구조에 따라 트리구조, 네트워크 구조, 리스트 구조, 규칙 등 다양한 구조로 나눈다. 구조의 차이는 단지 표현의 차이뿐만 아니라 그것이 갖는 문제해결 능력에도 차이가 있다. 본 논문에서는 모델을 간략화 시켜 오버피팅 문제를 해결하고 분류 능력을 향상시키는 방법을 제안한다. 모델을 단순화 시키는데 사용되는 파티션 유틸리티 기준함수 제시하고 휴리스틱을 이용하여 균형 잡힌 계층 구조를 생성하는 방법을 제안한다.

• 한국농공학회논문집
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• 제64권1호
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• pp.27-37
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• 2022

This study established a water supply network based on the operation case of Mandae Reservoir in Yanggu-gun, Gangwon-do, to analyze the efficient distribution and management of agricultural water supplied from the reservoir to irrigation areas using the hydraulic analysis model SWMM. In order to construct a model to analyze the water canal network, network conditions needs to be simplified, and in particular, excessive detail or simplification of the irrigation area can lead to errors in the analysis results. Therefore, the effect of the water canal network model was analyzed by simulating the appropriate simplification process step by step. The results of simplifying the actual block shape of the analysis target area using SWMM showed that there was no significant difference in the results even if 7 lots were simplified to 2. Also, it was found that the construction and analysis of a simplified network model were reliable when the excess quantity was 2% or more compared to the required quantity for each case of analysis of the paddy field.

• 농촌계획
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• 제11권1호
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• pp.9-15
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• 2005

Preservation of geometrical context of terrains in a digitized format is useful in handling and making modification to the data. Digitization of three-dimensional terrain still proves a great challenge due to heavy load of context required to retain details of topological and geometrical information. Methods of simplification, restoration and multi-level terrain generation are often employed to transform the original data into a compressed digital format. However, reduction of the stored data size comes at an expense of loss of details in the original data set. This article reports on an alternative scheme for simplification and restoration of terrain data. The algorithm utilizes the fact that the terrain formation and patterns can be predicted and modeled through the fractal algorithm. This method was used to generate multi-level terrain model based on NGIS digital maps with preserving geometrical context of terrains.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권1호
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• pp.16-21
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• 2004

This paper presents an approximation method for simplifying a high-order transfer function to a low-order transfer function. A model reduction is based on minimizing the error function weighted by the numerator polynomial of reduced systems. The proposed methods provide better low frequency fit and a computer aided algorithm that estimates the coefficients vector for the numerator and denominator polynomial on the simplified systems from an overdetermined linear system constructed by frequency responses of the original systems. Two examples are given to illustrate the feasibilities of the suggested schemes.

• 한국경영과학회지
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• 제24권4호
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• pp.111-122
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• 1999

In this paper, we consider a queueing network model. where the population constraint within each subnetwork is controlled by a semaphore queue. The total number of customers that may be present in the subnetwork can not exceed a given value. Each node has a constant service time and the arrival process to the queueing network is an arbitrary distribution. A major characteristics of this model is that the lower layer flow is halted by the state of higher layer. We present some properties that the inter-change of nodes does not make any difference to customer's waiting time in the queueing network under a certain condition. The queueing network can be transformed into a simplified queueing network. A dramatic simplification of the queueing network is shown. It is interesting to see how the simplification developed for sliding window flow control, can be applied to multi-layered queueing network.

• 한국지능시스템학회논문지
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• 제14권4호
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• pp.468-472
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• 2004

본 논문은 품질 검사, 홍채 위치 측정, 특징 추출, 검증으로 구성된 지능형 홍채 인식 시스템을 소개한다. 품질 검사를 위하여 동공 경계에 관한 국부적 통계를 사용한다. 홍채 영역을 분리하고 찾기 위하여 잘 알려진 가우시안 혼합 모형(Gaussian mixture model)을 사용한다. 특징 추출 방법은 최적화된 파형 단순화를 기초로 한다. 검증을 위해서 지능형 가변임계값을 사용한다.

• International Journal of CAD/CAM
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• 제8권1호
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• pp.37-40
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• 2009

Based on the study of Digital Elevation Simplification Model and fractal theory, this paper put forward a new method to simulate complex terrain. That use simplified DEM data to construct terrain frame based on the quad tree at first, and then use fractal to generate the details of every node of the tree. In the process of construction, the LOD theory is used to simplify the terrain and get its typical data. According to the change of view position and direction, the paper gives a new way to judge the visibility of the surface patch. Experimental results show that this algorithm is simple, efficient and supports the real time dynamic simulation of terrain model.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.555-561
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• 2024

This paper derives material properties of steel bars that simulate the distribution of stress and strain of prestressed tendons used in Prestressed concrete(PSC) girders and presents an optimal material model. ABAQUS software was used to establish the 3D solid model of the PSC girder and strand wire rope for a PS(Prestressed) tendon. Then the model of steel wire rope was imported into the Isight interface plugin directly through the ABAQUS and the Data Matching. In ABAQUS, the contact pairs were established, the models were meshed, the constraints were applied to solve the finite element model and an axial tension of 0.5m/s was loaded to analyze the stress and deformation distributions in the normal working range of the PS strand wire rope. In Data Matching, classical experimental data is fitted to the optimal material properties through finite element analysis and multi-objective optimization. The results show that the steel bar with optimal material properties presents a similar linear area and stress distribution with the PS tendon.

• 한국수자원학회논문집
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• 제51권4호
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• pp.347-354
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• 2018

도시유역에서 발생한 유출은 지표면뿐만 아니라 하수관망을 통해 배수되며, 도시침수 모의 수행시 하수관망을 수문학적 배수 시스템의 한 구성요로서 고려하는 것은 매우 중요하다. 그러나 도시 침수 모의를 수행하는 대부분의 연구자들이 적절한 기준에 준하지 않고 직관적으로 하수관망을 단순화시켜 모의를 수행하는 실정이다. 따라서 본 연구에서는 1D-2D 결합 도시침수 해석 모형을 이용하여 수지상 구조에 구분법에 기반하여 단순화된 하수관망의 도시침수 해석 결과에 미치는 영향을 분석하였다. 하수관망 해석을 위한 1차원 모델은 Lee et al. (2017)에 의해 소개된 모형으로서 지표면과 하수관망 사이의 유입과 역류를 동시에 모의할 수 있고, 2차원 지표면 모델은 불규칙 삼각망을 이용하여 지표수 흐름을 모의하며 1차원 하수관망 해석모형과 연계되어 도시침수를 모의할 수 있다. 하수관망은 수지상 구조 구분법에 기반하여 2차, 3차 그리고 단순화 하지 않은 경우로 구분할 수 있으며, 구분된 각 하수관망은 서울시 사당역 인근에 많은 침수 피해를 발생시킨 2011년 7월 27일 강우 사상에 적용하여 제안된 방법의 적용성을 평가하였다. 모든 케이스에 대하여 침수면적, 지표면에서 하수관망으로의 유입 유량, 하수관망에서 지표면으로의 역류 유량 등을 비교하였으며, 마지막으로 하수관망 단순화를 위한 적절한 기준 제시에 대한 논의를 수행하였다.