• 제목/요약/키워드: Numerical model experiments

검색결과 1,464건 처리시간 0.024초

수리모형과 수치해석을 통한 만곡부 하천의 수리학적 특성 비교 고찰 (A Comparative Study on Hydraulic Characteristics of Curved Channel by Hydraulic Model Experiments and Numerical Analysis)

  • 서동일;최한규
    • 산업기술연구
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    • 제27권A호
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    • pp.85-94
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    • 2007
  • This study, regarding curved channel, was performed to compare and analyze hydraulic characteristics and the speed of water and water level for left bank and right bank through hydraulic model experiments and numerical analysis. Real channels that had characteristics of curved channel were selected as objectives. In order to easily operate one and two dimensional numerical analysis and comparison for total 2.4Km model channel, measuring point was set up as 200m. HEC-RAS model was applied as one dimensional numerical analysis program and SMS model was used as two dimensional numerical analysis program. In respect of speed of water, the average speed of water for right bank recorded 8.33m/s in a model experiment and 3.08m/s, 8.57m/s were average speed of water for right bank in one dimensional and two dimensional numerical analysis. The average speed of water of two dimensional numerical analysis was quite similar to that of model experiments. Also, as for water level, maximum observational errors between one and two dimensional numerical analysis for right and left bank of model experiments were 0.66m, 0.84m and 0.28m, 0.48m for each. It was found that two dimensional numerical analysis had a similar result to hydraulic model experiments. Accordingly, from the result of this study, two dimensional numerical analysis should be used rather than one dimensional numerical analysis, when numerical analysis for curved channel is conducted.

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하천폭의 국부적 축소 및 확대에 따른 수리특성 연구 (A Study of the Stream Specific by River Width's Downsizing & Extension)

  • 최한규;김주석;백효선
    • 산업기술연구
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    • 제27권B호
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    • pp.229-233
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    • 2007
  • This research investigated the way of generating the flowing of water in case of artificial fluctuation of river width by the unidimensional numerical analysis in order to reconstruct vertical and expanse features of flowing, and the problem of existing numerical analysis in accordance with local enlargement and reduction of river through hydraulic model experiments with results of numerical analysis. The result revealed that when the local section change in the same river is exist, it showed 0.93m in the case of no change of local section in the hydraulic model experiments and numerical analysis, however, it presented 1.645m on the occasion of local section changes in the hydraulic model experiments and numerical analysis. In other words, there was a significant difference in the existing numerical analysis, when there was a local section change. As a result of the experimental section for the enlargement and reduction of local river width, due to the sensitive change for fluctuation of flood discharge, there was a significant difference between numerical analysis and hydraulic model experiments. In addition, the result of comparison between the enlargement and reduction of local river width confirmed that the result of numerical analysis with hydraulic model experiments showed larger generation of deviation in case of enlargement of section than in case of reduction of section.

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타원형 수중천퇴상의 규칙파 및 불규칙파의 전파변형 실험(I):비쇄파조건 (Experiments for Wave Transformation of Regular and Irregular Waves over a Submerged Elliptic Shoal(I) : Non-breaking Conditions)

  • 이종인;이정욱
    • 한국해안해양공학회지
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    • 제14권3호
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    • pp.240-246
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    • 2002
  • 타원형 천퇴해역에 대한 규칙파 및 일방향 불규칙파의 전파변형에 대한 수리모형실험을 수행하였다. 수리모형실험은 비쇄파조건의 규칙파와 천퇴의 정상부에서 부분쇄파가 발생하는 일방향 불규칙파를 대상으로 수행되었다. 수리모형실험 조건에 대해 포물형근사식을 적용한 수치해석을 수행하여 실험결과와 비교하였다.

해성점토 굴착사면의 거동에 관한 원심모형실험 및 수치해석 (Centrifuge Model Experiments and Numerical Analyses of the Behavior of Excavated Marine Clay Slope)

  • 박병수
    • 한국해양공학회지
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    • 제20권5호
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    • pp.49-56
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    • 2006
  • In this thesis, centrifuge model experiments and numerical analyses were carried out to investigate the behavior of an excavated slope in soft clay ground. Centrifuge model tests were performed with various slopes for the excavated ground, such as 1:1.5 and 1:2. Pore pressuresthe model ground were measured to find their effects on the stability of the excavated slope. These experiments showed that the model with 1:2.5 maintained its stability within a short period of time and failed gradually. Therefore, anexcavated slope of soft soil with this slope might maintain stable conditions within a certain time. The mode1 with a 1:3 slope was observed to maintain a very stable condition, showing insignificant deformation in the ground after being excavated. Numerical analyses with PLAXIS, a commerciallyavailable software implemented with the finite element numerical technique, were performed to find the pore pressure distribution within the ground mass and the deformation of the soil. From the results of numerical analysis, a negative pore pressure was developed after the excavation and thus the stability of the slope was maintained. The safety factor for slope failure was found to decrease with time because of the dissipation of negative pore pressure with time.

수치실험을 통한 스트레스 감소 예방보수모형의 고찰 (Numerical Experiments for the Stress-Reducing Preventive Maintenance Model)

  • 박종훈
    • 산업경영시스템학회지
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    • 제43권3호
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    • pp.41-52
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    • 2020
  • This paper investigates the stress-reducing preventive maintenance model through numerical experiments. The preventive maintenance model is used to analyze the relationship between related conditions and variables to gain insight into the efficient operation of the system when performing preventive maintenance in real-world situations. Various preventive maintenance models have been developed over the past decades and their complexity has increased in recent years. Increasing complexity is essential to reflect reality, but recent models can only be interpreted through numerical experiments. The stress-reducing preventive maintenance is a newly introduced preventive maintenance concept and can only be interpreted numerically due to its complexity, and has received little attention because the concept is unfamiliar. Therefore, for information purposes, this paper investigates the characteristics of the stress-reducing preventive maintenance and the relationship between parameters and variables through numerical experiments. In particular, this paper is focusing on the economic feasibility of stress-reducing preventive maintenance by observing changes in the optimal preventive maintenance period in response to changes in environmental stress and the improvement factor. As a result, when either the environmental stress or the improve effect of stress-reducing preventive maintenance is low, it is not necessary to carry out the stress-reducing preventive maintenance at excessive cost. In addition, it was found that the age reduction model is more economical than the failure rate reduction model.

Experimental and numerical investigations of near-field underwater explosions

  • Lee, Seunggyu;Cho, Junghee;Lee, Chaemin;Cho, Seongpil
    • Structural Engineering and Mechanics
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    • 제77권3호
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    • pp.395-406
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    • 2021
  • Near-field underwater explosion (UNDEX) phenomena were investigated by experiments and numerical simulations. The UNDEX experiments were performed in a water tank using a ship-like model. One kilogram of TNT, one of the most widely used military high explosives, was used for the experiments. Numerical simulations were performed under the same conditions as in the experiments using the commercial software LS-DYNA. Underwater pressures, accelerations, velocities, and strains by shock waves were measured at multiple locations. Further, the bubble pulsation period and the whipping deformations of the ship-like model were explored. The experimental results are presented and examined through comparison with the results obtained from widely used empirical equations and numerical simulations.

서리층 성장 예측을 위한 수치적 모델 (The numerical model for predicting frost layer growth)

  • 이관수;지성;이태희
    • 설비공학논문집
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    • 제9권2호
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    • pp.249-258
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    • 1997
  • In this study, a numerical model for analyzing frost formation phenomena on a cold flat plate has been developed. Both regions of air flow and frost layer have been coupled to calculate the amount of the heat and mass transfer between air flow and frost layer. Experiments have been also conducted to validate the numerical model. The present numerical results show a good agreement with the experimental data. The present numerical model also provides some useful data such as the temperature distribution inside the frost layer which could not be obtained through the experiments.

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OPTIMIZED NUMERICAL ANNULAR FLOW DRYOUT MODEL USING THE DRIFT-FLUX MODEL IN TUBE GEOMETRY

  • Chun, Ji-Han;Lee, Un-Chul
    • Nuclear Engineering and Technology
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    • 제40권5호
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    • pp.387-396
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    • 2008
  • Many experimental analyses for annular film dryouts, which is one of the Critical Heat Flux (CHF) mechanisms, have been performed because of their importance. Numerical approaches must also be developed in order to assess the results from experiments and to perform pre-tests before experiments. Various thermal-hydraulic codes, such as RELAP, COBRATF, MARS, etc., have been used in the assessment of the results of dryout experiments and in experimental pre-tests. These thermal-hydraulic codes are general tools intended for the analysis of various phenomena that could appear in nuclear power plants, and many models applying these codes are unnecessarily complex for the focused analysis of dryout phenomena alone. In this study, a numerical model was developed for annular film dryout using the drift-flux model from uniform heated tube geometry. Several candidates of models that strongly affect dryout, such as the entrainment model, deposition model, and the criterion for the dryout point model, were tested as candidates for inclusion in an optimized annular film dryout model. The optimized model was developed by adopting the best combination of these candidate models, as determined through comparison with experimental data. This optimized model showed reasonable results, which were better than those of MARS code.

연속철근 콘크리트 포장 수치해석 모델의 해석결과 정확도 개선 방법 (Accuracy Improvement of Analysis Results Obtained from Numerical Analysis Model of Continuously Reinforced Concrete Pavement)

  • 조영교;석종환;최린;김성민
    • 한국도로학회논문집
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    • 제18권1호
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    • pp.73-83
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    • 2016
  • PURPOSES : The purpose of this study is to develop a method for improving the accuracy of analysis results obtained from a two-dimensional (2-D) numerical analysis model of continuously reinforced concrete pavement (CRCP). METHODS : The analysis results from the 2-D numerical model of CRCP are compared with those from more rigorous three-dimensional (3-D) models of CRCP, and the relationships between the results are recognized. In addition, the numerical analysis results are compared with the results obtained from field experiments. By performing these comparisons, the calibration factors used for the 2-D CRCP model are determined. RESULTS : The results from the comparisons between 2-D and 3-D CRCP analyses show that with the 2-D CRCP model, concrete stresses can be overestimated significantly, and crack widths can either be underestimated or overestimated by a slight margin depending on the assumption of plane stress or plane strain. The behaviors of crack width in field measurements are comparable to those obtained from the numerical model of CRCP. CONCLUSIONS : The accuracy of analysis results from the 2-D CRCP model can be improved significantly by applying calibration factors obtained from comparisons with 3-D analyses and field experiments.