• Title/Summary/Keyword: computational results

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A COMPUTATIONAL APPROACH TO DESIGN THE GEOMETRY OF THE AIR-TWIST NOZZLE (Air-twist 노즐 형상 설계의수치적 연구)

  • Juraeva, M.;Song, D.J.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.67-70
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    • 2010
  • Spandex yarn requires a twisting process during winding and unwinding processes at the textile industry. The air-twist nozzle is widely used as part of the winding and unwinding. This paper describes computational approach to design the geometry of the air-twist nozzle. The nozzle has circular yarn-channel and the air-inlet which is perpendicularly connected to the yarn-channel with yarn-loading slit. The air-inlet of the nozzle is designed while measurements of the yarn-channel are fixed. The airflow inside the air-twist nozzle is simulated by using Computational Fluid Dynamic model. The Ansys CFX was used to perform steady simulations of the airflow for the air-twisting process. The vortical structure and the airflow pattern such as velocity streamline, vorticity, velocity of the air-twist nozzle are discussed. Computational results are compared with experimental results in this paper.

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A Computational Analysis and An Experimental Study on the effects of Concrete Shrinkage and Creep in Bridge Widening (교량 확폭시 콘크리트의 건조수축 및 크리이프의 영향에 관한 실험적 연구 및 해석)

  • 장동일;조병완;홍성욱
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1994.04a
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    • pp.163-170
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    • 1994
  • The widening of bridges under traffic condition brings to many problems. One of these is the internal stresses caused by different creep and shrinkage behavior of the existing bridge and that of the widened Bridge. This study was conducted to examine the effects of different creep and shrinkage behaviors between concretes. The results are as follows; Comparing the computational analysis results with the experimental study, it is shown that finite element analysis used in this study was well accorded with experimental results. And considering the shrinkage effects in widened bridges, joining-construction using the expanding concrete between the existing and widened bridge after at least three months from the day of completion of new bridge, is recommended.

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DYNAMIC STALL PREDICTION WITH TRANSITION OVER AN OSCILLATING AIRFOIL (천이를 고려한 진동하는 익형의 동적 실속 예측)

  • Jeon, Sang-Eon;Park, Soo-Hyung;Kim, Chang-Joo;Chung, Ki-Hoon;Jung, Kyung-Jin
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.358-361
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    • 2010
  • A Reynolds-Averaged Navier-Stokes (RANS) code with transition prediction model is developed and the computational results on an oscillating airfoil are compared with the experimental data for OA209 airfoil. An approximated eN method that can predict transition onset points and the length of transition region is directly applied to the RANS code. The hysteresis loop in dynamic stall is compared for the computational results using transition prediction and fully turbulent models with the experimental data. Results with transition prediction show more correlation with the experimental data than the fully turbulent computation.

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Analysis of Rarefied Flow Field Around a Flat Plate by the DSMC Method (DSMC 방법을 이용한 평판 주위의 희박류 해석)

  • Yoon Sung Joon
    • 한국전산유체공학회:학술대회논문집
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    • 1995.10a
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    • pp.235-240
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    • 1995
  • The paper describes hypersonic rarefied flow of helium and nitrogen over a flat plate by the direct simulation Monte Carlo (DSMC) method. The effect of incomplete accommodation and plate thickness are analyzed and the computational results are compared with wind tunnel test data. Also computational aspects of the method are outlined.

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SOME RESULTS OF MOMENTS IN MULTIVARIATE STATISTICAL DISTRIBUTION

  • Chul Kang;Park, Sang-Don
    • Journal of applied mathematics & informatics
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    • v.12 no.1_2
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    • pp.323-334
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    • 2003
  • We review the developmental history of the moment matrix of matrix quadratic form. This paper also investigates, the moment matrix of (non-central) Wishart distribution, which is multi-version of X$^2$ distribution.

Moment-rotation prediction of precast beam-to-column connections using extreme learning machine

  • Trung, Nguyen Thoi;Shahgoli, Aiyoub Fazli;Zandi, Yousef;Shariati, Mahdi;Wakil, Karzan;Safa, Maryam;Khorami, Majid
    • Structural Engineering and Mechanics
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    • v.70 no.5
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    • pp.639-647
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    • 2019
  • The performance of precast concrete structures is greatly influenced by the behaviour of beam-to-column connections. A single connection may be required to transfer several loads simultaneously so each one of those loads must be considered in the design. A good connection combines practicality and economy, which requires an understanding of several factors; including strength, serviceability, erection and economics. This research work focuses on the performance aspect of a specific type of beam-to-column connection using partly hidden corbel in precast concrete structures. In this study, the results of experimental assessment of the proposed beam-to-column connection in precast concrete frames was used. The purpose of this research is to develop and apply the Extreme Learning Machine (ELM) for moment-rotation prediction of precast beam-to-column connections. The ELM results are compared with genetic programming (GP) and artificial neural network (ANN). The reliability of the computational models was accessed based on simulation results and using several statistical indicators.

Automatic Parameter Tuning for Simulated Annealing based on Threading Technique and its Application to Traveling Salesman Problem

  • Fangyan Dong;Iyoda, Eduardo-Masato;Kewei Chen;Hajime Nobuhara;Kaoru Hirota
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2003.09a
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    • pp.439-442
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    • 2003
  • In order to solve the difficulties of parameter settings in SA algorithm, an improved practical SA algorithm is proposed by employing the threading techniques, appropriate software structures, and dynamic adjustments of temperature parameters. Threads provide a mechanism to realize a parallel processing under a disperse environment by controlling the flux of internal information of an application. Thread services divide a process by multiple processes leading to parallel processing of information to access common data. Therefore, efficient search is achieved by multiple search processes, different initial conditions, and automatic temperature adjustments. The proposed are methods are evaluated, for three types of Traveling Salesman Problem (TSP) (random-tour, fractal-tour, and TSPLIB test data)are used for the performance evaluation. The experimental results show that the computational time is 5% decreased comparing to conventional SA algorithm, furthermore there is no need for manual parameter settings. These results also demonstrate that the proposed method is applicable to real-world vehicle routing problems.

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Thermochemcial Characteristics of Rocket Nozzle Flow and Methods of Analysis (로켓 노즐 유동의 열/화학적 특징 및 해석 기법)

  • Choi Jeong-Yeol
    • 한국전산유체공학회:학술대회논문집
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    • 2001.05a
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    • pp.144-148
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    • 2001
  • Characteristics of high temperature rocket nozzle flow is discussed along with the aspects of computational analysis. Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were discussed those were coupled with the methods of computational fluid dynamics. A chemical equilibrium code developed for the analysis of general hydrocarbon fuel was coupled with three approaches of nozzle flow analysis, and a test was made for a bell nozzle at typical operation condition. As a results, the characteristics of the approaches were discussed in aspects of rocket performance, thermal analysis and computational efficiency.

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Computational analysis of vortex breakup in arrhythmias (심장 부정맥 시 vortex breakup 현상에 대한 수치적 연구)

  • Shim, Eun-Bo;Kwon, Soon-Sung;Choi, Seung-Yoon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.496-497
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    • 2008
  • In this study, we present the computational analysis of cardiac arrhythmias that is the major cause of human sudden cardiac death. First, electric excitation and condution in one dimensional cardiac tissue model is solved and the results on condution block are represented. In two dimensional model, vortex daynamics in cardiac tissue is analyzed to delineate the breakup phenomenon inducing ventricular fibrillation. We also simulated a three dimenional heart model to see the vortex breakup and explained the mechanism in physiological aspect.

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The Correlation between Unplugged Activities using SW Educational Board Games and the Computational Thinking of Elementary School Students (SW교육용 보드게임 활용 언플러그드 활동과 초등학생의 컴퓨팅 사고력의 관계)

  • Lee, Jaeho;Park, Injung
    • Journal of Creative Information Culture
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    • v.6 no.2
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    • pp.89-99
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    • 2020
  • The purpose of this study is to statistically analyze the correlation between unplugged activities using SW educational board games and computational thinking ability of elementary school students, and then find a method of SW education through the results. The study was conducted with 40 students in the 5th grade at an Elementary School in Incheon. Students participated at unplugged activities using a board game for SW education with 12 hours of teacher guidance and 10 hours of free activities. After that, a post-test was conducted to analyze the degree of improvement in computational thinking ability. As the results, it was confirmed that the comprehensive computational thinking ability was improved, and that the four areas of the sub-domains of computational thinking ability were improved to a significant level. These results suggest that providing a basic SW education experience by utilizing a board game for SW education helps to improve students' computational thinking ability.