• 한국멀티미디어학회논문지
• /
• 제9권9호
• /
• pp.1150-1159
• /
• 2006

본 논문에서는 지오데식 동적 윤곽선 모델을 이용하여 뇌실 영역을 검출하기 위하여 기존의 에지지시함수를 대신한 영역 기반의 곡선진행억제 함수를 제안하였다. 제안한 곡선 진행 억제 함수는 뇌실 영역의 검출에 매우 효과적이었으며, 이 함수는 MRI 영상에서 밝게 나타나는 뇌실 영역의 평균 밝기를 기반으로 한다. 본 논문에서는 제안한 방법이 기존의 방법보다 뇌실 영역을 잘 검출할 수 있음을 다양한 척도를 이용하여 수치적으로 비교하였다. 실제 정상과 뇌종양에 의한 뇌질환 영상에 적용시켜 뇌실 검출 과정을 시각적으로 비교하여 우수성을 검증하였다.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제13권1호
• /
• pp.39-49
• /
• 2013

This paper presents a method of improving the performance of a day-ahead 24-h load curve and peak load forecasting. The next-day load curve is forecasted using radial basis function (RBF) neural network models built using the best design parameters. To improve the forecasting accuracy, the load curve forecasted using the RBF network models is corrected by the weighted sum of both the error of the current prediction and the change in the errors between the current and the previous prediction. The optimal weights (called "gains" in the error correction) are identified by differential evolution. The peak load forecasted by the RBF network models is also corrected by combining the load curve outputs of the RBF models by linear addition with 24 coefficients. The optimal coefficients for reducing both the forecasting mean absolute percent error (MAPE) and the sum of errors are also identified using differential evolution. The proposed models are trained and tested using four years of hourly load data obtained from the Korea Power Exchange. Simulation results reveal satisfactory forecasts: 1.230% MAPE for daily peak load and 1.128% MAPE for daily load curve.

• 한국분무공학회지
• /
• 제4권1호
• /
• pp.55-61
• /
• 1999

The first maximum point in the stability curve of liquid jet, i.e., the critical point is associated with the critical Reynolds number. This critical Reynolds number should be predicted by simple means. In this work, the critical Reynolds number in the stability curve of liquid jet are predicted using the empirical correlations and the experimental data reported in the literatures. The critical Reynolds number was found to be a function of the Ohnesorge number, nozzle lengh-to-diameter ratio, ambient Weber number and nozzle inlet type. An empirical correlation for the critical Reynolds number as a function of the Ohnesorge number and nozzle length-to-diameter ratio is newly proposed here. Although an empirical correlation proposed in this work may not be universal because of excluding the effects of ambient pressure and nozzle inlet type, it has reasonably agrees with the measured critical Reynolds number.

• IEIE Transactions on Smart Processing and Computing
• /
• 제6권1호
• /
• pp.18-20
• /
• 2017

In this paper, we propose a new classification method to complement a $na{\ddot{i}}ve$ Bayesian classifier. This classifier assumes data distribution to be Gaussian, finds the discriminant function, and derives the decision curve. However, this method does not investigate finding the decision curve in much detail, and there are some minor problems that arise in finding an accurate discriminant function. Our findings also show that this method could produce errors when finding the decision curve. The aim of this study has therefore been to investigate existing problems and suggest a more reliable classification method. To do this, we utilize the gradient to find the decision curve. We then compare/analyze our algorithm with the $na{\ddot{i}}ve$ Bayesian method. Performance evaluation indicates that the average accuracy of our classification method is about 10% higher than $na{\ddot{i}}ve$ Bayes.

• Advances in materials Research
• /
• 제11권4호
• /
• pp.351-374
• /
• 2022

Softening function is the primary input for modeling the fracture of concrete when the cohesive crack approach is used. In this paper, based on the laboratory data on notched beams, an inverse algorithm is proposed that can accurately find the softening curve of the concrete. This algorithm uses non-linear finite element analysis and the damage-plasticity model. It is based on the kinematics of the beam at the late stages of loading. The softening curve, obtained from the corresponding algorithm, has been compared to other softening curves in the literature. It was observed that in determining the behavior of concrete, the usage of the presented curve made accurate results in predicting the peak loads and the load-deflection curves of the beams with different concrete mixtures. In fact, the proposed algorithm leads to softening curves that can be used for modeling the tensile cracking of concrete precisely. Moreover, the advantage of this algorithm is the low number of iterations for converging to an appropriate answer.

• 응용통계연구
• /
• 제14권1호
• /
• pp.71-80
• /
• 2001

로지스틱 회귀모형은 이항 반응자료에 대한 가장 보편적인 일반화 선형모형으로 독립변수에 대한 확률함수를 추정하는데 이용된다. 많은 실제적 상황에서 확률함수가 종형의 곡선형태로 표현되는데 이 경우에는 2차항을 포함한 로지스틱 회귀모형을 이용한 분석은 대칭성을 갖는 확률함수에 대한 가정으로 인해 비대칭 형태의 종형곡선에서는 확률함수의 신뢰성이 저하되고, 2차항을 포함하기 때문에 독립변수의 효과를 설명하기가 쉽지 않다는 제한점을 가지고 있다. 본 논문에서는 이러한 문제점을 해소하기 위해서 로지스틱 회귀분석과 반복적 이분법을 이용하여 종형의 형태에 관계없이 확률곡선을 추정하는 방법론을 제안하고 모의 실험을 통해 2차항을 포함한 로지스틱 회귀모형과 비교하고자 한다.

• 한국컴퓨터그래픽스학회논문지
• /
• 제16권4호
• /
• pp.41-50
• /
• 2010

본 논문에서는 계층적 B-spline곡선 (hierarchical B-spline curve)에 대한 새로운 다단계 편집 (multilevel editing)기법을 제안한다. 각 단계 변위함수 (displacement function)의 제어점 (control point)은 이전 단계 곡선위의 노드점 (nodal point)에서 계산되는 Rotation Minimizing Frame (RMF) [1]을 기준으로 표현된다. 이전 단계에서 곡선의 형상이 편집되면 해당노드 점에서 새로운 RMF가 계산되고, 현재 단계에서 변위함수의 제어점들은 새로운 RMF를 기준으로 적용되어, 현재 단계의 곡선은 이전 단계의 곡선에 대한 상대적인 세부 형상을 유지하게 된다. 본 논문에서는 다양한 형태의 곡선에 대한 다단계 편집실험을 통해 제안된 기법의 효율성과 안정성을 입증한다.

• 한국지반공학회논문집
• /
• 제29권2호
• /
• pp.57-64
• /
• 2013

본 논문에서는 정수슬러지의 고함수비 문제를 해결하고 재활용을 촉진하기 위해 정수슬러지와 화강풍화토를 다양한 배합비로 혼합하여 슬러지혼합토(sludge mixture)를 제작하고, 다양한 실내 시험을 통해 슬러지혼합토의 물리적 특성과 불포화 특성을 분석하였다. 시험 결과, 정수슬러지 함량이 증가함에 따라 동일한 모관흡수력에 대응하는 체적 함수비는 증가하였다. 또한 정수슬러지 함량 또는 세립분 함량이 증가함에 따라 공기함입치는 0.9kPa에서 2.4kPa로 증가하였다. 슬러지혼합토의 포화투수계수 값과 함수특성곡선의 결과를 활용하여 강우 시 침투해석을 수행하는데 있어서 중요한 인자인 불포화 투수함수를 산정하였다.

• 한국태양에너지학회 논문집
• /
• 제33권4호
• /
• pp.51-58
• /
• 2013

A study on power performance testing of a wind turbine which has no met-mast at a distance of 2~4 rotor diameter was carried out using the Nacelle Transfer Function, NTF, according to IEC 61400-12-2. The wind data for this study was measured at HanKyoung wind farm of Jeju Island. The NTF was modeled using the correlation between wind speeds from the met-mast and from the wind turbine nacelle within 2~4 rotor diameter from the met-mast. The NTF was verified by the comparison of estimated Annual Energy Productions, AEPs, and binned power curves. The Nacelle Power Curve, NPC, was derived from the nacelle wind speed data corrected by NTF. The NPC of wind turbine under test and the power curve offered by the turbine manufacturer were compared to check whether the wind turbine is properly generating electricity. Overall the NPC was in good agreement with the manufacturer's power curve. The result showed power performance testing for a wind turbine which has no met-mast at a distance of 2~4 rotor diameter was successfully carried out in compliance with IEC 61400-12-2.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
• /
• pp.334-337
• /
• 2006

Generally, fragility curve has been used in predicting failure of structures due to seismic actions. In this research, the method of drawing fragility curve has been applied to evaluating success/failure of structures and satisfactory/unsatisfactory of concrete mixture performance based on material parameters. In the paper, a detailed explanation of the procedure of drawing fragility curve based on material parameter has been introduced. Fragility curve generating procedure includes generation of virtual data points from limited number of actual data points by bell curve implementation, determination of success/failure status of each data point by assigned criterion, and completion of final fragility curve. For practical applications, workability of concrete mixture content based on "unit water" has been used to obtain fragility curve. Detailed explanation of fragility curve drawing procedure for material parameters is presented.