• 대한토목학회논문집
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• 제26권1D호
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• pp.59-66
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• 2006

이 연구는 도시고속도로의 진입연결로 접속부내 선형의 밀도예측모형 구축에 관한 연구로서 실시간 교통특성분석과 선형의 밀도예측모형 구축 및 검증을 통해 밀도예측모형 구축에 있어서 결정계수($R^2$)값이 대체적으로 0.7이상으로 나타나 선형회귀모형구축에 상당히 높은 설명력을 보이는 것으로 나타났고, 선형모형검증에 있어서 상관계수(r)값도 대체적으로 0.8 이상으로 상당히 높은 상관성을 보이는 것으로 나타났다. 따라서 향후 선형의 밀도예측모형을 이용하여 도시고속도로의 진입연결로 접속부내 차량의 밀도추정 및 지체분석에 상당히 유효할 것으로 판단된다.

• Korean Journal of Radiology
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• 제22권10호
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• pp.1697-1707
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• 2021

The recent introduction of various high-dimensional modeling methods, such as radiomics and deep learning, has created a much greater diversity in modeling approaches for survival prediction (or, more generally, time-to-event prediction). The newness of the recent modeling approaches and unfamiliarity with the model outputs may confuse some researchers and practitioners about the evaluation of the performance of such models. Methodological literacy to critically appraise the performance evaluation of the models and, ideally, the ability to conduct such an evaluation would be needed for those who want to develop models or apply them in practice. This article intends to provide intuitive, conceptual, and practical explanations of the statistical methods for evaluating the performance of survival prediction models with minimal usage of mathematical descriptions. It covers from conventional to deep learning methods, and emphasis has been placed on recent modeling approaches. This review article includes straightforward explanations of C indices (Harrell's C index, etc.), time-dependent receiver operating characteristic curve analysis, calibration plot, other methods for evaluating the calibration performance, and Brier score.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.302-307
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• 2006

The purpose of this paper is to develop an improved three-phase transformer model for ATP and parameter estimation methods that can efficiently utilize the limited available information such as factory test reports. In this paper, improved topologically-correct duality-based models are developed for three-phase autotransformers having shell-form cores. The problem in the implementation of detailed models is the lack of complete and reliable data. Therefore, parameter estimation methods are developed to determine the parameters of a given model in cases where available information is incomplete. The transformer nameplate data is required and relative physical dimensions of the core are estimated. The models include a separate representation of each segment of the core, including hysteresis of the core, ${\lambda}-i$ saturation characteristic and core loss.

• 안보군사학연구
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• 통권1호
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• pp.191-229
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• 2003

Multi-sensor data fusion techniques combine evidences from multiple sensors in order to get more accurate and efficient meaningful information through several process levels that may not be possible from a single sensor alone. One of the most important parts in the data fusion system is the identification fusion, and it can be categorized into physical models, parametric classification and cognitive-based models, and parametric classification technique is usually used in multi-sensor data fusion system by its characteristic. In this paper, we propose a novel heuristic identification fusion method in which we adopt desirable properties from not only parametric classification technique but also cognitive-based models in order to meet the realtime processing requirements.

• 대한기계학회논문집B
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• 제22권1호
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• pp.70-78
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• 1998

The present study has tested semi-empirical loss models for a reliable performance prediction of mixed-flow pumps with four different specific speeds. In order to improve the predictive capabilities, this paper recommends a new internal loss model and a modified parasitic loss model. The prediction method presented here is also compared with that based on two-dimensional cascade theory. Predicted performance curves by the proposed set of loss models agree fairly well with experimental data for a variety of mixed-flow pumps in the normal operating range, but further studies considering 'droop-like' head performance characteristic due to flow reversal in mixed-flow impellers at low flow range near shut-off head are needed.

• 한국농공학회논문집
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• 제49권2호
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• pp.27-36
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• 2007

This study, the present study wishes to develop a model that estimates shear strength characteristics of steel fiber reinforced concrete using artifical neural network models. Neural network models, developed as mathematical models, are being widely used not only in its original purpose of pattern recognition, but also in application fields by the function's nonlinear loaming and interpolar ability Neural network has a repetitive rotation algorithm that can cyclically and repeatedly estimate system conditions and parameter ideal values, and it can be used in the modeling of the nonlinear system by nonlinear characteristic functions that construct the system.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.113-122
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• 2002

The purpose of this study is to verify that the modified Lagrangian model can predict temperature, flow and scalar fields in the high temperature recirculation region of swirling confined diffusion flame. In the meantime numerical results from EBU and Equilibrium PDF models as well as experimental results are compared with those from the modified Lagrangian model. Adaption of three different turbulent models were accompanied with this procedure. Look-up table of the ignition characteristic time scale which is one of important factors of the Lagrangian model was referred to the 11-step reduced mechanism. Eventually, results with the Lagrangian model show a good accordance with experimental results, which shows the validity of this model. Results from Chen's model differ from those of the others. Numerical results of ${\widetilde{k}$ show significant deviation from experimental results for three models.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.110-115
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• 2000

The mean streamline analysis using the empirical loss correlations has been developed for performance prediction of industrial mixed-flow fan impellers in the present study. New simple, but effective, models for the additional Euler input work characteristic and an internal recirculation loss due to internal flow reversal under the low flowrate conditions are proposed in this paper. Comparison of overall performance predictions with six sets of test data of mixed-flow fans is accomplished to demonstrate the accuracy of the proposed models. Predicted performance curves by the present set of loss models agree fairly well with experimental data for a variety of mixed-flow fan impellers over the entire operating conditions. The prediction method presented herein can be used efficiently in the conceptual design phase of mixed-flow fan impellers.

• 전자공학회논문지D
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• 제35D권7호
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• pp.63-71
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• 1998

Generally, electronic packaging designer uses HSPICE SOFTWARE TOOL to validate electric characteristics of traces layout before layout traces in PCB in hundreds Mb/s high speed digital circuits. We are in need of a plated through hole (PTH) model and a connector model to use HSPICE SOFTWARE TOOL. Those models have not been perfectly defined for HSPICE simulation. In this paper, we define a PTH model and a connector model for HSPICE simulation and discuss application range for these models. Th emodels are analytic models very applicable for HSPICE simulation and are used to analyze electric characteristic of the PTH and the connector in thetraces layout in high speed digital circuit.

• International Journal of Aerospace System Engineering
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• 제6권2호
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• pp.11-16
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• 2019

A system analysis program has been developed for a gas generator cycle liquid rocket engine of 30 ton class. Numerical models have been proposed for a combustor, a turbopump, a gas generator and pressure drop through a regenerative cooling system. Numerical algorithm has been validated by comparing with the published data of MC-1. The major source of error is not the numerical algorithm but the imperfect performance models of subsystems. So the precision of the program can be improved by revising the performance models using experimental data. The sea level specific impulse and vacuum specific impulse have been demonstrated for a 30 ton class gas generator engine. The optimal condition of combustor pressure and mixture ratio for specific impulse which is a typical characteristic of a gas generator cycle engine has been illustrated.