• Title/Summary/Keyword: Optimization condition

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Probabilistic optimization of nailing system for soil walls in uncertain condition

  • Mitra Jafarbeglou;Farzin Kalantary
    • Geomechanics and Engineering
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    • v.34 no.6
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    • pp.597-609
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    • 2023
  • One of the applicable methods for the stabilization of soil walls is the nailing system which consists of tensile struts. The stability and safety of soil nail wall systems are influenced by the geometrical parameters of the nailing system. Generally, the determination of nailing parameters in order to achieve optimal performance of the nailing system for the safety of soil walls is defined in the framework of optimization problems. Also, according to the various uncertainty in the mechanical parameters of soil structures, it is necessary to evaluate the reliability of the system as a probabilistic problem. In this paper, the optimal design of the nailing system is carried out in deterministic and probabilistic cases using meta-heuristic and reliability-based design optimization methods. The colliding body optimization algorithm and first-order reliability method are used for optimization and reliability analysis problems, respectively. The objective function is defined based on the total cost of nails and safety factors and reliability index are selected as constraints. The mechanical properties of the nailing system are selected as design variables and the mechanical properties of the soil are selected as random variables. The results show that the reliability of the optimally designed soil nail system is very sensitive to uncertainty in soil mechanical parameters. Also, the design results are affected by uncertainties in soil mechanical parameters due to the values of safety factors. Reliability-based design optimization results show that a nailing system can be designed for the expected level of reliability and failure probability.

Optimization of sidewalls for a Double-Passage Cascade Experiment (2피치 유로 캐스케이드 실험을 위한 벽면 최적화에 관한 연구)

  • Cho, Choong-Hyun;Ahn, Koo-Kyoung;Cho, Soo-Yong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.10
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    • pp.969-978
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    • 2008
  • In a linear cascade experimental apparatus, when it adopts only few blades as well as satisfies the periodic condition between blades, it gives several advantages in experiment. In this study, wall design on a cascade experimental apparatus is conducted to obtain the periodic condition on two blades installed within a passage of which the width is double pitch. The Mach number difference on the blade surface obtained with the periodic and wall condition is chosen as an objective function, and twelve design variables which are related to the wall shape are selected. A wall shape is designed using a gradient-based optimization method. Adjustment of range and weighting function are applied to calculate the objective function to avoid unrealistic evaluation of the objective function. By applying these methods, the computed results show same flow structures obtained with the periodic condition.

Optimization of Operating Condition on Gasification of Ash-free Coal by Using the Sensitivity Analysis of ASPEN Plus (민감도 해석을 통한 무회분 석탄의 가스화 최적 운전조건 도출)

  • Park, Sung-Ho;Jeon, Dong-Hwan;Yun, Sung-Phil;Chung, Seok-Woo;Choi, Ho-Kyung;Lee, Si-Hyun
    • Clean Technology
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    • v.20 no.3
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    • pp.298-305
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    • 2014
  • Ash included in coal can cause environmental pollution and it can decrease efficiency of mass and heat transfer by getting scorched and stick in the facilities operated at high temperature. To solve this problem, a feasibility study on pulverized coal fired power plant and integrated gasification combined cycle (IGCC) using the AFC (Ash-Free Coal) as well as the development to remove the ash from the coal was conducted. In this research, optimization of operating condition was proposed by using sensitivity analysis of ASPEN $Plus^{(R)}$ to apply the coal containing under the 200 ppm ash for integrated gasification combined cycle. Particularly, the coal gasification process was classified as three parts : pyrolysis process, volatile matter combustion process and char gasification process. The dimension and operating condition of 1.5 ton/day class non-slagging gasifier are reflected in the coal gasification process model.

Optimization of Microwave-Assisted Extraction under Atmospheric Pressure Condition for Soluble Ginseng Components (상압조건의 마이크로웨이브 추출공정에서 가용성 인삼성분의 추출조건 최적화)

  • Kwon, Joong-Ho;Kim, Kyung-Eun;Lee, Gee-Dong
    • Korean Journal of Food Science and Technology
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    • v.32 no.1
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    • pp.117-124
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    • 2000
  • Considering the thermal unstableness of ginseng components, microwave-assisted extraction(MAE) was performed under the atmospheric pressure condition. The monitoring of extraction characteristics and the optimization of extraction conditions were made by response surface methodology. The extraction efficiency of soluble ginseng components was high at lower ethanol concentration and at higher microwave power, while crude saponin content was easily extracted at higher ethanol concentration. Estimated conditions for the maximized extraction of soluble components including crude saponin, total phenolics and electron donating ability were $54{\sim}60%$ in ethanol concentration, $41{\sim}90$ W in microwave power, and within 4 min in extraction time. Predicted values at the optimum condition(60% ethanol, 80 W microwave power and 4 min extraction time) were in good agreement with observed values.

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Optimization of Extraction Condition of Hesperidin in Citrus unshiu Peels using Response Surface Methodology

  • Lee, Jua;Park, Shinyoung;Jeong, Ji Yeon;Jo, Yang Hee;Lee, Mi Kyeong
    • Natural Product Sciences
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    • v.21 no.2
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    • pp.141-145
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    • 2015
  • Hesperidin, which is the most abundant flavonoid of Citrus unshiu (Rutaceae), has been reported to possess diverse activities and widely used as functional foods and cosmetics. For the development of functional products, extraction procedure is indispensable. Extraction conditions affect the composition of extract as well as its biological activity. Therefore, we tried to optimize extraction conditions such as extraction solvent, extraction time and extraction temperature for maximum yield of hesperidin using response surface methodology with threelevel-three-factor Box-Behnken design (BBD). Regression analysis showed a good fit of the experimental data and the optimal condition was obtained as ethanol concentration, 59.0%; temperature $71.5^{\circ}C$ and extraction time, 12.4 h. The hesperidin yield under the optimal condition was found to be $287.8{\mu}g$ per 5 mg extract, which was well matched with the predicted value of 290.5 μg. These results provides optimized extraction condition for hesperidin and might be useful for the development of hesperidin as functional products like health supplements, cosmetics and medicinal products.

Design Optimization of a Wing Structure under Multi Load Spectra using PSO algorithm (PSO 알고리즘을 이용한 다중 하중 스펙트럼 하에서의 항공기 날개 구조부재의 최적 설계 연구)

  • Park, Kook Jin;Park, Yong Jin;Cho, Jin Yeon;Park, Chan Yik;Kim, Seung Jo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.11
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    • pp.963-971
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    • 2012
  • In this paper, development of optimal design tools for wing structure is described including multi load spectra condition and fatigue analysis. Two dimensional CFD result are used for calculating aerodynamic force. Design variables are composed of a number of rib and spar, positions, and thickness of each structural member. The mission profile for fatigue analysis is composed based upon the results of CFD analysis, the flight-by-flight spectra method, the excessive curves for gust loads. Minor's rule was used to deal with multi-load condition. Stress analysis and fatigue analysis are performed to calculate objective functions. Particle Swarm Optimization(PSO) algorithm was used to apply to problems which have dozens of design variables.

Optimization of Fermentation Conditions for the Production of Citric Acid by Aspergillus niger NRRL 567 Grown on Agricultural by Products (목질계 농부산물을 이용한 고체발효에서 발효조건 최적화를 통한 구연산 생산 증대)

  • Kim, Jin-Woo
    • Korean Chemical Engineering Research
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    • v.52 no.3
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    • pp.402-406
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    • 2014
  • The present study was carried out to evaluate the potential of lignocellulosic byproducts for the production of citric acid through solid-state fermentation by Aspergillus niger NRRL 567. A sequential optimization based on one-factor-at-a-time method was applied to optimize fermentation conditions and media constituents. The results obtained from the optimization indicated that $30^{\circ}C$, 70% moisture content, 0.5~1.0 mm particle size, pH 5.5 and 4% methanol were found to be the optimum condition at 72 hr fermentation. The application the optimization resulted in an improvement of maximum citric acid production from 74.5 to 206.0 g/kg dry material (DM) from wheat straw. The optimal condition was used to produce citric acid from A. niger grown on different lignocellulosic byproducts, including wheat straw, corn stover and peat moss. A. niger produced the highest citric acid levels of 231.8, 213.8 and 240.2 g/kg DM at 120 hr fermentation, respectively.

Design and Optimization of an Knee Joint of Fully-active Transfemoral Prosthesis for Stair Walking (계단 보행을 위한 능동형 대퇴의지 무릎 관절의 설계 및 최적화)

  • Ahn, Hyoung-Jong;Lee, Kwang-Hee;Hong, Yi;Lee, Chul-Hee
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.10 no.1
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    • pp.65-72
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    • 2016
  • In this study, a fully active transfemoral prothesis with a knee joint is designed considering stair walking conditions. Since the torque at the knee joint required for stair walking condition is relative high compared with the one in normal walking condition, the proposed design has high torque generating mechanism. Moreover, the transfemoral prothesis is designed in compact size to reduce its weight, which is related to comfortable fit and fatigue of patients. Flat type BLDC motor is used for simple and compact structure and various components are used to generate required torque with target working angle and speed. The weight reduction of structure is carried out using optimization method after the initial design process is complete. The optimization is conducted under the load conditions of stair walking. The optimized design is validated via finite element analysis and experiments. As a result, the weight is reduced using topology and shape optimization but maintaining the safety of structure. Also the space efficiency is improved due to its compact size.

Water Recources Evaluation using Network Optimization Model (Network Optimization Model을 이용한 수자원 평가)

  • Lee, Gwang-Man;Lee, Jae-Eung;Sim, Sang-Jun;Go, Seok-Gu
    • Journal of Korea Water Resources Association
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    • v.32 no.2
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    • pp.143-152
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    • 1999
  • South-eastern part of Kyungbuk Province is suffering from lack of suitable water development sources due to geographic condition and insufficient water sources condition. In order to find an appropriate solution, extensive studies are carried out such as investigation of new dam sites, regional water supply system, modification of existing water supply system, rehabilitation of old water resources structures and development of off-stream reservoirs. The network optimization model is applied for evaluation of the newly suggested water development alternatives. The results show that if water supply system is constructed until 2011, the reliability of water supply to Pohang and Kyungju region will be more than 95% and the network optimization model can be used to analyse the management of water resources system considering water rights or priority orders.

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Optimum Design of the Spatial Structures using the TABU Algorithm (TABU 알고리즘을 이용한 대공간 구조물의 최적설계)

  • Cho Yong-Won;Lee Sang-Ju;Han Sang-Eul
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2005.04a
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    • pp.273-280
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    • 2005
  • The design of structural engineering optimization is to minimize the cost. This problem has many objective functions formulating section and shape as a function of the included discrete variables. simulated annealing, genetic algerian and TABU algerian are searching methods for optimum values. The object of this reserch Is comparing the result of TABU algorithm, and verifying the efficiency of TABU algorithm in structural optimization design field. For the purpose, this study used a solid truss of 25 elements having 10 nodes, and size optimization for each constraint and load condition of Geodesic ome, and shape optimization of Cable Dome for verifying spatial structures by the application of TABU algorithm.

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