• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.803-812
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• 2008

Along with the increasing demand for automatic and mechanical tunnel excavation methods in Korea, the Tunnel Boring Machine (TBM) method of tunnel excavation has become increasingly popular. However, in spite of this rising demand, few studies have been performed on the TBM method, in Korea. For this reason, this study focused on evaluation of the applicability of TBM performance prediction models based on field data in order to contribute to the basic and essential parts of TBM designation and the TBM method of tunnel excavation in Korea. These rock properties can be defined as the mechanical and physical factors of rock that have an influence on a disc cutter's ability to cut rock, and provide information for the evaluation of the applicability of field data. Based on outcomes from these tests, applicability of the prediction model was evaluated and the predicted performance of a TBM was compared with real field data obtained from four different TBM construction sites in Korea.

• Wind and Structures
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• 제22권4호
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• pp.477-501
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• 2016

Though hilly topography influences both wind speeds and directions aloft, only the influence on wind speeds, i.e. the speed-up effect, has been thoroughly investigated. Due to the importance of a model showing the spatial variations of wind directions above hilly terrains, it is worthwhile to systematically assess the applicability and limitations of the model describing the influence of hilly topographies on wind directions. Based on wind-tunnel test results, a model, which describes the horizontal and vertical variations of the wind directions separately, has been proposed in a companion paper. CFD (Computational Fluid Dynamics) techniques were employed in the present paper to evaluate the applicability of the proposed model. From the investigation, it has been found that the model is acceptable for describing the vertical variation of wind directions by a shallow hill whose primary-to-secondary axis ratio (aspect ratio) is larger than 1. When the overall hill slope exceeds $20^{\circ}$, the proposed model should be used with caution. When the aspect ratio is less than 1, the proposed model is less accurate in predicting the spatial variation of wind directions in the wake zone in a separated flow. In addition, it has been found that local slope of a hill has significant impact on the applicability of the proposed model. Specifically, the proposed model is only applicable when local slope of a hill varies gradually from 0 (at the hill foot) to the maximum value (at the mid-slope point) and then to 0 (at the hill top).

• Steel and Composite Structures
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• 제31권1호
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• pp.85-98
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• 2019

Nonlinear seismic performances of code designed Perforated Steel Plate Shear Walls (P-SPSW) were studied. Three multi-storey (4-, 8-, and 12-storey) P-SPSWs were designed according to Canadian seismic provisions and their performance was evaluated using time history analysis for ground motions compatible with Vancouver response spectrum. The selected code designed P-SPSWs exhibited excellent seismic performance with high ductility and strength. The current code equation was found to provide a good estimation of the shear strength of the perforated infill plate, especially when the infill plate is yielded. The applicability of the strip model, originally proposed for solid infill plate, was also evaluated for P-SPSW and two different strip models were studied. It was observed that the strip model with strip widths equal to center to center diagonal distance between each perforation line could reasonably predict the inelastic behavior of unstiffened P-SPSWs. The strip model slightly underestimated the initial stiffness; however, the ultimate strength was predicted well. Furthermore, applicability of simple shear-flexure beam model for determination of fundamental periods of P-SPSWs was studied.

• 한국해양환경ㆍ에너지학회지
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• 제13권4호
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• pp.270-278
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• 2010

선행연구에서 우리나라 남해안을 대상으로 상용모형인 MIKE21 모형을 사용하여 실시간 조석 및 조석-해일 결합모형을 수립하였다. 본 연구에서는 이를 토대로 마산해역에서 범람모의에 대한 적용성을 검토하였다. 실제 적용에 앞서 가상적인 인공구조물의 범람에 대한 영향성 분석을 시행하였다. 범람 모의에 인공구조물을 포함시킨 결과 침수속도가 지체되어 침수면적이 감소하고 있는 반면 침수심은 별 차이를 보이지 않고 있다. 한편 실해역에 대한 결합모형과 폭풍해일모형의 범람 적용을 비교한 결과, 침수면적과 침수심은 유사한 결과를 보이고 있는 반면 최대 범람에 이르는 시간은 결합모형이 보다 타당한 결과를 나타내고 있다.

• 통합자연과학논문집
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• 제14권3호
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• pp.99-106
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• 2021

A mixture of alcohol and water is commonly used as antifreeze, liquor, and the fundamental solvents for the manufacture of cosmetics, pharmaceuticals, and inks in our daily life. Since various properties of alcohol water mixtures such as density, boiling or melting point, viscosity, and dielectric constant are determined by their mixing ratio, it is very important to know the mixing ratio to predict their properties. One of simple method to find the mixing ratio is measuring the density of the mixtures. However, it is not easy to predict the mixing ratio from the density of the mixtures because the relationship between mixing ratio and density has not been established well. The relationship is dependent on the relative sizes of solute and solvent molecules, and their interactions. Recently, an empirical model to predict the density of glycerol water mixture from their mixing ratio has been introduced. The suggested model is simple but quite accurate for glycerol water mixture. In this article, we investigated the applicability of this model to different alcohol water mixtures. Densities for six different alcohol water mixtures containing various alcohols (e.g., ethylene glycol, 1,3-propane diol, propylene glycol, methanol, ethanol, and 1-propanol) were simulated and compared to experimentally measured ones to investigate the applicability of the model proposed for glycerol water mixtures to other alcohol water mixtures. The model predicted the actual density of all alcohol water mixtures tested in this article with high accuracy at various ratios. This model can probably be used to predict the mixing ratio of other alcohol water mixtures from their densities beyond 6 alcohols tested in this article from their densities.

• 한국농공학회논문집
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• 제62권4호
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• pp.53-61
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• 2020

The laboratory model test was conducted by dividing domestic reclaimed tideland into Sandy Loam (SL) and Silt Clay Loam (SiCL) to estimate soil moisture change and water supply according to soil characteristic when establishing irrigation plan for reclaimed tideland upland crop. In addition, the applicability of each scenario was verified using Van Genuchten model, which is the most widely used mathematical model for analyzing soil moisture characteristics of reclaimed tideland uplands crops. The required water supply according to the target soil moisture tension by reclaimed tideland is as follow. In the case of SL, soil depths of 0~10 cm, 10~20 cm were analyzed as 19 mm, 35 mm to reach the field capacity, and SiCL, 33 mm, 63 mm. The required water supply of SiCL was higher than that of SL. The study compared the simulation results from the scenarios of Van Genuchen model and the measured results from the laboratory model test based on according to the reclaimed tidelands. In the case of parameter, θ_s, θ_r, α, η were analyzed 0.55, 0.18, 0.064, 1.74 in SL and 0.46, 0.22, 0.105, 1.92 in SiCL. In terms of soil characteristics, SL with better water permeability was found to have higher applicability than SiCL. By Soil depth, applicability was found in 0~10 cm directly affected by water supply.

• Journal of the Korean Data and Information Science Society
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• 제28권6호
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• pp.1447-1456
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• 2017

강우현상을 구조적으로 모형화한 확률적 강우모의모형의 활용성이 증대되는 상황에서 확률적 강우모의모형의 모수에 대한 정확한 추정은 매우 중요하다. 본 연구에서는 확률적 강우모의모형 (Neyman-Scott rectangular pulse model, NSRPM)의 모수를 DFP (Davidon-Fletcher-Powell), GA (genetic algorithm), Nelder-Mead, DE (differential evolution) 기법으로 추정하고 추정된 모수의 적합성을 분석하고 지역특성에 적합한 모수 추정 기법을 제시하였다. 낙동강 유역의 20개 강우 관측 지점을 대상으로 1973년-2017년 기간 동안의 여름철 1시간 강수자료 이용하여 산정된 모형 모수를 분석한 결과, 전반적으로 DE, Nelder-Mead기법이 가장 좋은 결과를 보였으며 DFP, GA기법은 상대적으로 낮은 적합도를 보였다.

• Steel and Composite Structures
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• 제19권5호
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• pp.1055-1075
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• 2015

In order to investigate the accuracy and applicability of steel equivalent constitutive model, the calculated results were compared with typical tests of steel frames under static and dynamic loading patterns firstly. Secondly, four widely used models for time history analysis of steel frames were compared to discuss the applicability and efficiency of different methods, including shell element model, multi-scale model, equivalent constitutive model (ECM) and traditional beam element model (especially bilinear model). Four-story steel frame models of above-mentioned finite element methods were established. The structural deformation, failure modes and the computational efficiency of different models were compared. Finally, the equivalent constitutive model was applied in seismic incremental dynamic analysis of a ten-floor steel frame and compared with the cyclic hardening model without considering damage and degradation. Meanwhile, the effects of damage and degradation on the seismic performance of steel frame were discussed in depth. The analysis results showed that: damages would lead to larger deformations. Therefore, when the calculated results of steel structures subjected to rare earthquake without considering damage were close to the collapse limit, the actual story drift of structure might already exceed the limit, leading to a certain security risk. ECM could simulate the damage and degradation behaviors of steel structures more accurately, and improve the calculation accuracy of traditional beam element model with acceptable computational efficiency.

• 한국철도학회논문집
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• 제10권2호
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• pp.224-230
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• 2007

The performance and applicability of FDS code is analyzed for flow simulation in railway tunnel. FDS has been built in NIST(USA) for simulation of fire-driven flow. RANS and DNS's results are compared with FDS's. AJL non-linear ${\kappa}-{\epsilon}$[7,8] model is employed to calculate the turbulent flow for RANS. DNS data by Moser et al.[9] are used to prove the FDS's applicability in the near wall region. Parallel plate is used for simplified model of railway tunnel. Geometrical variables are non-dimensionalized by the height (H) of parallel plate. The length of streamwise direction is 50H and the length of spanwise direction is 5H. Selected Re numbers are 10,667 for turbulent flow and 133 for laminar low. The characteristics of turbulent boundary layer are introduced. AJL model's predictions of turbulent boundary layer are well agreed with DNS data. However, the near wall turbulent boundary layer is not well resolved by FDS code. Slip conditions are imposed on the wall but wall functions based on log-law are not employed by FDS. The heavily dense grid distribution in the near wall region is necessary to get correct flow behavior in this region for FDS.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.79-83
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• 2015

The Response to Intervention(RTI) approaches is the method to help students who are at risk for learning difficulties in advance and provide an appropriate level of intervention. In this article, the characteristics of model RTI were reviewed for students with achievement of below basic proficiency level. We considered RTI as supporting system to document students' progress and its applicability for the general educational setting in Korean school. The tier of RTI make it possible the evidence based individual instruction and counseling, differentiated step-by step approach for students with achievement of below basic proficiency level. In conclusion, RTI can be used as educational tools for dealing with improvement of academic subjects learning, behavioral and emotional problem for students with achievement of below basic proficiency level. For building high quality implementing for RTI it is needed the collaboration of teachers, counselors and learning consultants and related educators.