• Structural Engineering and Mechanics
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• 제53권4호
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• pp.833-845
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• 2015

Natural frequencies of the structural systems should be far away from the excitation frequency in order to avoid or reduce the destructive effects of dynamic loads on structures. To accomplish this goal, a structural optimization on size and shape has been performed considering frequency constraints. Such an optimization problem has highly nonlinear property. Thus, the quality of the solution is not independent of the optimization technique to be applied. This study presents the performance evaluation of the recently proposed meta-heuristic algorithm called Teaching Learning Based Optimization (TLBO) as an optimization engine in the weight optimization of the truss structures under frequency constraints. Some examples regarding the optimization of trusses on shape and size with frequency constraints are solved. Also, the results obtained are tabulated for comparison. The results demonstrated that the performance of the TLBO is satisfactory. Additionally, TLBO is better than other methods in some cases.

• 말소리와 음성과학
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• 제1권2호
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• pp.129-140
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• 2009

The purpose of the present study is to investigate frequency related information and syllable structure constraints on Sino-Korean. Previous studies on Sino-Korean have mostly investigated the historical change of sounds and reviewed archaic features of Chinese language in Sino-Korean. Unfortunately, there is little study on the sounds of contemporary Sino-Korean in terms of syllable structure constraints. For the purpose of the present study, sounds of 7,742 Chinese characters used in Sino-Korean (7,795 syllables) were investigated and syllable matrices made based on the results of frequency related information. As a result, 483 syllable types were observed and the most frequently observed syllables were as follows: /ku/ (103) > /ki/ (100) > /ju/ (87) > /pi/ (86). Only 16 out of 19 consonants are used for Sino-Korean. /$t^{\ast}$/ and /$p^{\ast}$/ are never used in Sino-Korean and /kh, $s^{\ast}$, $k^{\ast}$/ occur only a few times (3, 2, 1 respectively). /k/ (17.5%) shows the highest frequency and /n, ${\eta}$, 1, tc, m/ occupied the next rankings. Among 20 vowel types, /a/ showed the highest frequency and /o, u, i, $j{\Lambda}$, ${\Lambda}$/ occupied the next rankings. Based on the syllable matrices, gaps were observed and classified into accidental or systematic ones. Onset and nucleus, nucleus and coda, onset and coda, and other syllable structure constraints of Sino-Korean were listed.

• 대한건축학회논문집:구조계
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• 제35권10호
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• pp.135-142
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• 2019

Ant colony optimization(ACO) technique is utilized in truss size optimization with frequency constraints. Total weight of truss to be minimized is considered as the objective function and multiple natural frequencies are adopted as constraints. The modified traveling salesman problem(TSP) is adopted and total length of the TSP tour is interpreted as the weight of the structure. The present ACO-based design optimization procedure uses discrete design variables and the penalty function is introduced to enforce design constraints during optimization process. Three numerical examples are carried out to verify the capability of ACO in truss optimization with frequency constraints. From numerical results, the present ACO is a very effective way of finding optimum design of truss structures in free vibration. Finally, we provide the present numerical results as future reference solutions.

• 한국콘텐츠학회논문지
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• 제9권12호
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• pp.826-835
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• 2009

이 연구의 목적은 시큐리티요원들의 여가유형에 따른 여가제약과 참가의 관계를 규명하는데 있다. 이 연구는 2009년 서울소재 14개소 민간경비회사를 모집단으로 설정한 다음, 유의표집법을 이용하여 최종분석에 사용된 사례 수는 총 387명이다. 설문지의 신뢰도는 Cronbach's $\alpha$값이 .673이상으로 나타났다. 결론은 다음과 같다. 첫째, 성별에 따라서는 여성 집단에서 개인적, 시간적 제약이 높으며, 연령에 따라서는 26-30세 집단에서 시간적 제약, 36세 이상의 집단에서 주변 의식적 제약이 높다. 학력에 따라서는 고졸 이하 집단에서 주변 의식적, 대인적 제약, 전문대졸 집단에서는 구조적 제약이 높으며, 월수입에 따라서는 100만원 미만의 집단에서 주변 의식적, 구조적, 개인적, 대인적 제약이 높다. 직위에 따라서는 팀장급에서 주변 의식적, 구조적, 개인적, 시간적 제약이 높으며, 근무형태에 따라서는 신변보호원 집단이 개인적 제약, 기계경비원 집단에서는 주변 의식적, 구조적, 시간적 제약, 그리고 기타 사무직에서 대인적 제약이 높다. 둘째, 취미 교양 활동의 경우 시간적 제약이 많을수록 참가빈도, 구조적 제약이 많을수록 참가기간, 개인적 제약이 많을 수록 참가강도는 감소한다. 반면, 시간적 제약이 많음에도 참가강도는 증가한다. 놀이 오락 활동의 경우 주변 의식적 제약이 많음에도 참가빈도 및 기간, 개인적 제약이 많음에도 참가기간이 증가한 반면, 구조적 제약이 많을수록 참가빈도 및 기간은 감소한다. 관람 감상 활동의 경우 대인적 제약이 많음에도 참가빈도 및 기간, 시간적 제약이 많음에도 참가기간은 증가한 반면, 구조적 제약이 많을수록 참가빈도 및 기간은 감소한다.

• Steel and Composite Structures
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• 제30권1호
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• pp.47-55
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• 2019

The aim of this paper is to present new and an efficient optimization algorithm called Jaya for the optimum mass of braced dome structures with natural frequency constraints. Design variables of the bar cross-section area and coordinates of the structure nodes were used for size and shape optimization, respectively. The effectiveness of Jaya algorithm is demonstrated through three benchmark braced domes (52-bar, 120-bar, and 600-bar). The algorithm applied is an effective tool for finding the optimum design of structures with frequency constraints. The Jaya algorithm has been programmed in MATLAB to optimize braced dome.

• Journal of Information Processing Systems
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• 제16권5호
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• pp.1129-1144
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• 2020

The thangka image inpainting method based on wavelet transform is not ideal for contour curves when the high frequency information is repaired. In order to solve the problem, a new image inpainting algorithm is proposed based on edge structural constraints and wavelet transform coefficients. Firstly, a damaged thangka image is decomposed into low frequency subgraphs and high frequency subgraphs with different resolutions using wavelet transform. Then, the improved fast marching method is used to repair the low frequency subgraphs which represent structural information of the image. At the same time, for the high frequency subgraphs which represent textural information of the image, the extracted and repaired edge contour information is used to constrain structure inpainting in the proposed algorithm. Finally, the texture part is repaired using texture synthesis based on the wavelet coefficient characteristic of each subgraph. In this paper, the improved method is compared with the existing three methods. It is found that the improved method is superior to them in inpainting accuracy, especially in the case of contour curve. The experimental results show that the hierarchical method combined with structural constraints has a good effect on the edge damage of thangka images.

• Structural Engineering and Mechanics
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• 제13권5호
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• pp.479-490
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• 2002

The structural dynamic optimization problem based on probability is studied. Considering the randomness of structural physical parameters and the given constraint values, we develop a dynamic optimization mathematical model of engineering structures with the probability constraints of frequency, forbidden frequency domain and the vibration mode. The sensitivity of structural dynamic characteristics based on probability is derived. Two examples illustrate that the optimization model and the method applied are rational and efficient.

• 한국해양공학회지
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• 제27권5호
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• pp.36-42
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• 2013

We present the optimum design for the cross-sectional(sizing) and shape optimization of truss structures with natural frequency constraints. The optimum design method used in this paper employs continuous design variables and the Harmony Search Algorithm(HSA). HSA is a meta-heuristic search method for global optimization problems. In this paper, HSA uses the method of random number selection in an update process, along with penalty parameters, to construct the initial harmony memory in order to improve the fitness in the initial and update processes. In examples, 10-bar and 72-bar trusses are optimized for sizing, and 37-bar bridge type truss and 52-bar(like dome) for sizing and shape. Four typical truss optimization examples are employed to demonstrate the availability of HSA for finding the minimum weight optimum truss with multiple natural frequency constraints.

• Advances in Computational Design
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• 제1권2호
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• pp.119-138
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• 2016

In this article, hybridization of enhanced colliding bodies optimization (ECBO) with upper bound strategy (UBS) that is called UECBO is proposed for optimum design of truss structures with frequency constraints. The distinct feature of the proposed algorithm is that it requires less computational time while preserving the good accuracy of the ECBO. Four truss structures with frequency limitations selected from the literature are studied to verify the viability of the algorithm. This type of problems is highly non-linear and non-convex. The numerical results show the successful performance of the UECBO algorithm in comparison to the CBO, ECBO and some other metaheuristic optimization methods.

• 한국생산제조학회지
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• 제22권1호
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• pp.63-69
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• 2013

In order to find the optimum design of structures that have characteristic natural frequency range, a numerical optimization method to solving eigenvalue problems is a widely used approach. However in the most cases, it is difficult to decide the accurate thickness and shape of structures that have allowable natural frequency in design constraints. Parallel analysis algorithm involving the feasible direction optimization method and Rayleigh-Ritz eigenvalue solving method is developed. The method is implemented by using finite element method. It calculates the optimal thickness and the thickness ratio of individual elements of the 2-D plane element through a parallel algorithm method which satisfy the design constraint of natural frequency. As a result this method of optimization for natural frequency by using finite element method can determine the optimal size or its ratio of geometrically complicated shape and large scale structure.