• Fisheries and Aquatic Sciences
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• 제18권3호
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• pp.265-271
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• 2015

A feeding trial of four dietary protein levels (20, 30, 40, and 50%) and two lipid levels (7 and 14%) with a factorial design was conducted to determine the optimal dietary protein and lipid levels for juvenile Israeli carp Cyprinus carpio. Triplicate groups of fish (average body weight, $1.3{\pm}0.02g$) were fed the experimental diets for 9 weeks. Survival of fish was not affected by either dietary protein or dietary lipid level. Weight gain and feed efficiency increased as dietary protein levels increased up to 40 and 50%, respectively. Weight gain was higher in fish fed the high-lipid diets with 20 and 40% protein content. Feeding efficiency increased as the dietary lipid level increased for the 30, 40, and 50% protein diets. Daily feed intake decreased with increasing protein level and the minimum feed consumption was observed in fish fed the 50% protein diet with 14% lipid content. Moisture and lipid contents of the whole body were affected by both dietary protein and lipid levels. The crude lipid content of fish fed the 14% lipid diet was higher than that of fish fed the 7% lipid diet at each protein level. The results of this study indicate that a diet containing 40% protein with 14% lipid content is optimal for the growth and effective protein utilization of juvenile Israeli carp.

• Computers and Concrete
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• 제28권5호
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• pp.465-478
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• 2021

On the premise of ensuring that the static performance of the concrete spreader is met, the first-order natural frequency of the concrete spreader is increased, and the weight of the main beam is reduced. ANSYS is used as an analysis tool to perform modal analysis on the concrete spreader. The natural frequency, mode shape and modal test verification will be obtained to ensure the accuracy of finite element model analysis. Using the ANSYS designxplorer module, the size of the main beam is set, and the response surface model between the parameter variables and the optimization objective is established according to the experimental design points. Screening algorithm and MOGA algorithm are used to multi-optimize the stress, first-order natural frequency and girder weight, and the optimal solution is obtained by comparison. The results of modal analysis are consistent with those of the experiment, and a set of optimal solutions is obtained through the optimization algorithm. The optimal solution obtained can meet the purpose of increasing the first-order natural frequency of the concrete spreader and reducing the weight of the main beam under the premise of ensuring the overall dynamic and static performance of the concrete spreader.

• 대한토목학회논문집
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• 제6권2호
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• pp.111-120
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• 1986

강재(鋼材) 뼈대 구조물(構造物)은 널리 사용(使用)되는 기본적(基本的)인 구조물(構造物)로서, 소성(塑性)힌지의 개념(槪念)을 도입(導入)한 설계(設計) 및 해석방법(解析方法)이 적절(適切)히 적용(適用)되고 있는 경우(境遇)라고 볼 수 있다. 소성해석(塑性解析)의 목적(目的)은 구조물(構造物) 각(各) 부재(部材)의 소성(塑性)모멘트를 알고 있을 때 붕괴하중(崩壞荷重)을 결정(決定)하는 것이며, 소성최적설계(塑性最適設計)의 목적(目的)은 구조물(構造物)의 총중량(總重量)을 최소(最小)로 하는 부도재(部都材)의 소성(塑性)모멘트를 결정(決定)하는 것이다. 본(本) 논문(論文)에서는 소성해석(塑性解析) 및 최적설계(最適設計)를 정적접근방법(靜的接近方法)(static approach)을 사용(使用)하여 Simplex method에 의해 해결(解決)하였다. 소성해석(塑性解析)의 경우(境遇), 종래(從來)의 계산시간(計算時間)을 훨씬 줄일 수 있었으며, 또한 본(本) 연구(硏究)에서 2층 구조물(構造物)의 최적설계시(最適設計時) 구조물(構造物)의 중량(重量)은 탄성설계(彈性設計)와 비교(比較)하여 약(約) 24%가 절약(節約)되었다.

• 한국정밀공학회지
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• 제19권9호
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• pp.186-192
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• 2002

As industry is developed, the faster transportation of freight train is demanded. The optimum design of a structure requires the determination of economical member size and shape of a structure which will satisfy the design conditions and the functions. In this study, it is attempted to minimize the dead weight of bogie frame. From the numerical results in the shape and size optimization of the bogie frame, it is known that the weight can be reduced up to 17.45% with the displacement, stress, first natural frequency and critical buckling-load constraints. The first natural frequency and the critical buckling load of the optimized model is larger than that of the lowest design value. Stress and displacement conditions are also satisfied within the design conditions. From the results, the optimal model is stable and useful for the improvement of railway carriages.

• 한국군사과학기술학회지
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• 제15권1호
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• pp.93-100
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• 2012

In this paper, the deterministic optimal design for the tail plane made of composite materials is conducted under the deterministic loading condition and compared with that of the metallic materials. Next, the reliability analysis with five random variables such as loading and material properties of unidirectional prepreg is conducted to examine the probability of failure for the deterministic optimal design results. The MATLAB programing is used for reliability analysis combined with FEA S/W(COMSOL) for structural analysis. The laminated composite is assumed to the equivalent orthotropic material using classical laminated plate theory. The response surface methodology and importance sampling technique are adopted to reduce computational cost with satisfying the accuracy in reliability analysis. As a result, structural weight of composite materials is lighter than that of metals in deterministic optimal design. However, the probability of failure for the deterministic optimal design of the tail plane structures is too high to be neglected. The sensitivity of each variable is also estimated using probabilistic sensitivity analysis to figure out which variables are sensitive to failure. The computational cost is considerably reduced when response surface methodology and importance sampling technique are used. The study of the computationally inexpensive method for reliability-based design optimization will be necessary in further work.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.79-86
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• 2005

This paper deals with the static optimal shapes of simple beams which are subjected to a vertical point load. The area and second moment of inertia of the regular polygon cross-section of the tapered beams are determined, which have always same volume and same length for the parabolic taper. The differential equation governing the elastic curve is derived using the small deflection theory and solved numerically. By using the numerical results of deflections, rotations and bending stresses of such beams, the optimal shapes, namely, optimal section ratios, of the beams subjected to a single point load according to variation of load position parameters are determined and presented in the figures. Examples of the static optimal shapes for beams with a single load and multiple loads are reported. The design process of this study can be used directly for the minimum weight design of simple beams.

• 한국산업융합학회 논문집
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• 제26권5호
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• pp.895-905
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• 2023

Mud tanks used for storing and supplying mud in mud supply systems are essential to secure structural stability according to the mud loads inside the tank. In terms of structural stability of the mud tank can be ensured by increasing the thickness of the structure. However, increasing the thickness may cause a problem of increasing production costs. In addition, this increases the weight of the tank, which can cause problems with the trailer loading weight limitation during transportation. To satisfy both these problems and structural stability, the mud tank should be optimally designed. Therefore, this study conducted an optimum design in consideration of the load of the mud tank through the structural analysis and response surface optimization method in ANSYS.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 추계학술대회 논문집
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• pp.229-230
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• 2006

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.173-180
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• 2001

In this study steel box girders used as main members of a two span continuous steel bridge, are optimally designed by a Load and Resistance Factor Design method(LRFD) using an numerical optimization method. The width, height, web thickness and flange thickness of the main girder are set as design variables, and light weight design is attempted by choosing the cross-sectional area as an object function. We studied the results of steel box girders and compared with those of 1-type girders. The main program is coded with C++ and connected with optimization modul ADS. which is coded with FORTRAN.

• Smart Structures and Systems
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• 제26권5호
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• pp.545-558
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• 2020

A design method of a Multiple Tuned Mass Damper (MTMD) system is presented for wind induced vibration control of a cable-supported roof structure. Modal contribution analysis is carried out to determine the dominating modes of the structure for the MTMD design. Two MTMD systems are developed for two most dominating modes. Each MTMD system is composed of multiple TMDs with small masses spread at multiple locations with large responses in the corresponding mode. Frequencies of TMDs are distributed uniformly within a range around the dominating frequencies of the roof structure to enhance the robustness of the MTMD system against uncertainties of structural frequencies. Parameter optimizations are carried out by minimizing objective functions regarding the structural responses, TMD strokes, robustness and mass cost. Two optimization approaches are used: Single Objective Approach (SOA) using Sequential Quadratic Programming (SQP) with multi-start method and Multi-Objective Approach (MOA) using Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The computation efficiency of the MOA is found to be superior to the SOA with consistent optimization results. A Pareto optimal front is obtained regarding the control performance and the total weight of the TMDs, from which several specific design options are proposed. The final design may be selected based on the Pareto optimal front and other engineering factors.