• Steel and Composite Structures
• /
• 제47권5호
• /
• pp.569-585
• /
• 2023

This paper proposes an efficient approach for the structural topology optimization of bi-directional functionally graded structures by incorporating popular radial basis functions (RBFs) into an implicit level set (ILS) method. Compared to traditional element density-based methods, a level set (LS) description of material boundaries produces a smoother boundary description of the design. The paper develops RBF implicit modeling with multiquadric (MQ) splines, thin-plate spline (TPS), exponential spline (ES), and Gaussians (GS) to define the ILS function with high accuracy and smoothness. The optimization problem is formulated by considering RBF-based nodal densities as design variables and minimizing the compliance objective function. A LS-RBF optimization method is proposed to transform a Hamilton-Jacobi partial differential equation (PDE) into a system of coupled non-linear ordinary differential equations (ODEs) over the entire design domain using a collocation formulation of the method of lines design variables. The paper presents detailed mathematical expressions for BiDFG beams topology optimization with two different material models: continuum functionally graded (CFG) and mechanical functionally graded (MFG). Several numerical examples are presented to verify the method's efficiency, reliability, and success in accuracy, convergence speed, and insensitivity to initial designs in the topology optimization of two-dimensional (2D) structures. Overall, the paper presents a novel and efficient approach to topology optimization that can handle bi-directional functionally graded structures with complex geometries.

• 한국디자인학회:학술대회논문집
• /
• 한국디자인학회 2005년도 추계 학술발표대회 논문집
• /
• pp.92-93
• /
• 2005

• 대한가정학회지
• /
• 제39권12호
• /
• pp.1-14
• /
• 2001

The purpose of this study was to analyze the current states of interior design as a major at vocational high schools and to suggest ways in which it can be improved. Three hundred and four students and twelve teachers of two vocational high schools comprised the sample population for this study. Data was collected using two methods, questionnaires and interviews. Frequency distribution, mean, and chi-square tests were used to analyze the data. The findings of this study are as follows: The student respondents were more interested in studying residential design, furniture design and making, drafting and perspective drawing than other areas of study. Most teachers had difficulties teaching the subject of residential design because they were not well educated with this area. Surprisingly most students hoped to extend their education to a university or college after graduation, not to enter the workforce. According to teachers'responses, almost ninety percentage of students entered university or college. And more than two thirds of the students desired to study an interior design related major at the university level. Among graduates having jobs, half of them were working in interior design fields. If the students had to choose their jobs, they would work in interior design fields. The variables differentiating several related careers after graduation were school, grade, and sex. The students viewed interior design, interior coordination, and CAD related work as fields likely to enter upon graduating from vocational high schools; however, teachers viewed furniture making, interior accessorizing, and home fashion as fields more appropriate to the students'level of training. The teacher respondents criticized the textbooks in four categories; suitability with the students'level was average or below average; students'interest level and students'understanding level were average or above average; and whether the book was easy or difficult to be utilized for the purposes of teaching was also average or above average. The criticism was a little diverse depending on each book or each chapter. The teachers pointed out several problems using those books, such as insufficient examples or explanation, lack of coherence between some chapters, and an incompatibility with the allotted time frame in class. The merits of the textbooks varied such as a well organized structure, ability to generate students'interest. This study revealed that the strategy for improving the interior design major at vocational high schools should invoke, 1) dividing students into two groups-one to enter a university; the other to have jobs after graduation to focus their interests. 2) improving textbooks more appropriate to the students. 3) providing present teachers the opportunities for in-service training and hiring new teachers with credentials more suitable to educate students who desire to be interior designers.

• 대한전자공학회논문지SD
• /
• 제47권2호
• /
• pp.106-114
• /
• 2010

본 논문은 기가 스케일 System on Chip(SoC)를 위한 통합 설계 및 검증 플랫폼을 제안한다. VLSI 집적도의 발달로 그 복잡도가 증가하여 기존의 RTL 설계 방식으로는 그 생산성 차이(Production Gap)를 극복할 수 없게 되었다. 또한, 검증 차이(Verification Gap)의 증가로 검증 방법론에도 커다란 변혁이 필요하게 되었다. 본 플랫폼은 기존의 상위 수준 합성을 포함하며, 그 결과물을 이용하여 저 전력 설계의 전원 인식 검증 플랫폼과 검증 자동화를 개발하였다. 상위 수준 합성 시 사용되는 Control and Data Row Graph (CDFG)와 고 입력인 상위 수준 언어와 RTL를 기반으로 한 검증 플랫폼 자동화와 전원 인식 검증 방법론을 개발하였다. 검증 플랫폼에는 자동 검사 기능을 포함하고 있으며 Coverage Driven Verification을 채택하고 있다. 특히 전원 인식 검증을 위하여 개발된 조건 랜덤 벡터 생성 알고리듬을 사용하여 랜덤 벡터의 개수를 최소 5.75배 감소시키는 효과를 가져왔고, 전원과 전원 셀에 대한 모델링 기법을 이용하여 일반적인 로직 시뮬레이터 툴을 통해서도 전원 인식 검증을 가능하게 하였다. 이러한 통합된 설계 및 검증 플랫폼은 시스템 수준의 설계에서 검증, 합성에 이르는 전 설계 흐름을 완전 자동화 하여 상위 수준의 설계와 검증을 가능하게 하고 있다.

• 한국전산구조공학회논문집
• /
• 제23권5호
• /
• pp.465-473
• /
• 2010

건물의 높이와 세장비가 증가함에 따라 건물의 최대 횡변위와 풍응답 가속도와 같은 사용성 요구조건을 만족시키는 것이 고층건물 구조설계에 있어서 중요한 설계요소가 되고 있다. 풍응답 가속도는 거주자에게 불쾌함을 유발시키는 직접적인 원인이 되지만, 초기 구조 설계단계에서 구조 설계자가 풍응답을 조절할 수 있는 실용적인 방법은 개발되어 있지 못하다. 본 연구에서는 재분배기법을 이용하여 건물의 강성을 조절함으로써 고층건물의 풍응답 가속도를 조절할 수 있는 방법을 제안하였다. ASCE 7-02, NBCC 95, ISO 6897 등의 설계 코드 및 기준에 의하면 고층건물의 풍응답 가속도는 1차 고유주기에 반비례한다는 사실에 근거하여 본 연구에서는 물량을 재분배하여 건물의 1차 고유주기를 조절함으로서 풍응답 가속도를 조절하는 실용적 풍응답 가속도 조절 설계법을 제안한다. 제안된 설계법은 42층 건물의 풍응답 가속도 조절 설계에 적용하여 그 적용성과 효율성을 평가하였다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
• /
• pp.497-500
• /
• 2008

해양 환경에 노출된 구조물의 열화를 평가하는데 있어서 신뢰성을 확보하기 위해서는 기존의 사양설계에 비해 한 단계 발전된 신뢰성에 기반한 확률론적 설계가 필요하다. 또한 내구성 설계에 있어서 중요한 변수가 되는 임계염화물량은 국내 콘크리트 시방서에서 $1.2kg/m^3$으로 결정되었으나, 실설계 적용시 과다 설계를 유발하는 등의 문제를 보여주고 있다. 본 논문에서는 기존 문헌을 통해 임계염화물량의 확률 특성을 결정하고, 실제 실험 및 문헌 고찰을 통하여 표면염화물량, 확산계수, 피복두께의 확률적 특성을 고려하였다. 이를 이용하여 Monte Carlo Simulation을 활용한 신뢰성 염해 내구성 해석을 침매 터널 구조물에 대해 수행하여 대상 구조물의 염해내구성능을 평가하고 콘크리트 표준시방서에서 제시한 부식 임계 염소이온농도에 대한 타당성을 검토하였다. 분석 결과, 현실적인 염해 내구성 설계 및 평가를 위하여 기존에 제안된 $1.2kg/m^3$의 임계값에 대한 검토 및 개선이 필요함을 알 수 있었다.

• 한국주거학회논문집
• /
• 제22권3호
• /
• pp.73-82
• /
• 2011

The purpose of this study was to develop the curriculum of spatial convergence studies for the major field of housing and interior design. Documentary research and content analysis methods were used in this study. Data drawn from internet homepage of each universities which were 20 colleges the major field of housing and interior design and 160 colleges of architectural design, and public institutions the MLTM and the KRIHS. The major results of this study were as follows. 1) Government has been supported the specialized graduate school of spatial information and the university which they have spatial information curriculum during 5 years. 2) The department of spatial information has been educated the theory and practice about spatial issues in order to train the spatial specialist helpful to the new growing industry. 3) There were little changed curriculum which has related to the department of housing and interior design. The half of their curriculum were housing project and interior design. The spatial convergence studies educational program should be grow up step by step. The first is basic level to learn the basic theory of spatial studies for example the spatial introduction or the housing and the second is low level to learn the depth theory of spatial studies for example the design I or the housing development. The third is middle level to apply the depth theory of spatial studies for examples the design II, III or housing policy and institutions. And the last is high level to practice the depth theory of spatial studies for example housing construction or internship.

• Journal of Computing Science and Engineering
• /
• 제2권4호
• /
• pp.340-356
• /
• 2008

The cognitive constraints of the human mind must drive the decisions in architecture and methodology design in order that the systems we build are comprehensible. This paper presents a methodology for the design of time-triggered embedded systems that leads to understandable artifacts. We lift the design process to a higher level of abstractionto the level of computational components that interact solely by the exchange of messages. The time-triggered architecture makes it possible to specify the temporal properties of component interfaces precisely and provides temporally predictable message communication, such that the precise behavior of a large design can be studied in the early phases of a design on the basis of the component interface specifications. This paper shows how the cognitive simplification strategies of abstraction, partitioning and segmentation are supported by the time-triggered architecture and its associated design methodology to construct evolvable embedded systems that can be readily understood and modified.

• 한국소음진동공학회논문집
• /
• 제14권10호
• /
• pp.939-944
• /
• 2004

The numerical methods including the performance analysis and the noise prediction of the centrifugal compressor impeller are coupled with the optimization design skill, which consists of response surface method, statistical approach, and genetic algorithm. The flow-field Inside of a centrifugal compressor is obtained numerically by solving Wavier-Stokes equations. and then the propagating noise is estimated from the distributed surface pressure by using Ffowcs Williams-Hawkings formulation. The quadratic response surface model with D-optimal 3-level factorial experimental design points is constructed to optimize the impeller geometry for the advanced centrifugal compressor. The statistical analysis shows that the quadratic model exhibits a reasonable fitting quality resulting in the impeller blade design with high performance and low far-field noise level. The influences of selected design variables, objective functions, and constraints on the impeller performance and the impeller noise are also examined as a result of the optimization process.

• 설비공학논문집
• /
• 제7권1호
• /
• pp.1-12
• /
• 1995

In order to seek various relationships among many design parameters employed in the design of the axial-flow fans the program which generates acoustic spectrum has been developed and its validity verified. Outputs of the program, with other outputs from a formerly developed performance prediction program, have been used to form a multi-objective function, for which an optimal design process was carried out. The present analysis shows that overall noise level and efficiency has contrasting trends, and the chord length turns out to be the most critical design variable. In the chosen design case of requirements $Q=2000m^2/min$, ${\Delta}P_s=67mmAq$, D=1.4m, the chord length of 0.2059m minimizes the overall noise level, while chord length of 0.1254m maximizes the efficiency. The resulting chord length in the balanced optimization is 0.1809m.