• International Journal of Contents
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• 제10권1호
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• pp.23-28
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• 2014

When developing a classifier using various objective functions, it is important to compare the performances of the classifiers. Although there are statistical analyses of objective functions for classifiers, simulation results can provide us with direct comparison results and in this case, a comparison criterion is considerably critical. A Receiver Operating Characteristics (ROC) graph is a simulation technique for comparing classifiers and selecting a better one based on a performance. In this paper, we adopt the ROC graph to compare classifiers trained by mean-squared error, cross-entropy error, classification figure of merit, and the n-th order extension of cross-entropy error functions. After the training of feed-forward neural networks using the CEDAR database, the ROC graphs are plotted to help us identify which objective function is better.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.576-579
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• 2006

This paper describes characteristics and procedure of the basic design of large scale solar thermal power plant system. The evaluation is based on the operating data of CESA-I, solar central receiver plant. In order to evaluate the solar irradiation on the receiver, it is necessary to calculate the amount of thermal energy consumption at steam turbine and storage system in the STPPS. Especially, it is need to take into account of the storage and operating time to design a plant efficiently. In addition, basic design is performed for the CESA-I using the software tool of THERMOFLEX program. Based on the results, It is at lowed to use the program to investigate detail performance of each units of the STPPS by varying the operating conditions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.698-701
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• 2007

DAHAN, the first 1 MWe Solar Power Tower system locates north to Beijing where nearby The Great Wall is now under construction with cooperation between China and Korea. Results in predicting the preliminary performance of this central receiver system are presented in this paper. Operating cycles under some typical weather condition days are simulated and commented. These results can be used to assess the impact of alternative plant designs or operating strategies on annual energy production, with the final objective being to optimize the design of central receiver power plants. Two subsystems are considered in the system simulation: the solar field and the power block. Mathematic models are used to represent physical phenomena and relationships so that the characteristics of physical processes involving these phenomena can be predicted. Decisions regarding the best position for locating heliostats relative to the receiver and how high to place the receiver above the field constitute a multifaceted problem. Four different kinds of field layout are designed and analyzed by the use of ray tracing and mathematical simulation techniques to determine the overall optical performance ${\eta}_{field}$ and the spillage ${\eta}_{spill}$.The power block including a Rankine cycle is analyzed by conventional energy balance methods.

• 대한의용생체공학회:의공학회지
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• 제21권2호
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• pp.137-144
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• 2000

Clustered microcalcifications in X-ray mammograms are an important sign for the diagnosis of breast cancer. A shape-based method, which is based on the morphological features of clustered microcalcifications, is proposed for classifying clustered microcalcifications into benign or malignant categories. To verify the effectiveness of the proposed shape features, clinical mammograms were used to compare the classification performance of the proposed shape features with those of conventional textural features, such as the spatial gray-leve dependence method and the wavelet-based method. Image features extracted from these methods were used as inputs to a three-layer backpropagation neural network classifier. The classification performance of features extracted by each method was studied by using receiver operating-characteristics analysis. The proposed shape features were shown to be superior to the conventional textural features with respect to classification accuracy.

• Journal of Information Processing Systems
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• 제8권2호
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• pp.241-262
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• 2012

An understanding of quality attributes is relevant for the software organization to deliver high software reliability. An empirical assessment of metrics to predict the quality attributes is essential in order to gain insight about the quality of software in the early phases of software development and to ensure corrective actions. In this paper, we predict a model to estimate fault proneness using Object Oriented CK metrics and QMOOD metrics. We apply one statistical method and six machine learning methods to predict the models. The proposed models are validated using dataset collected from Open Source software. The results are analyzed using Area Under the Curve (AUC) obtained from Receiver Operating Characteristics (ROC) analysis. The results show that the model predicted using the random forest and bagging methods outperformed all the other models. Hence, based on these results it is reasonable to claim that quality models have a significant relevance with Object Oriented metrics and that machine learning methods have a comparable performance with statistical methods.

• 한국음향학회지
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• 제33권2호
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• pp.139-145
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• 2014

본 논문에서는 WPD (Wavelet Packet Decomposition) 계수에 Teager 에너지를 적용한 특징 계수를 임계값 알고리듬에 적용하여 잡음에 강인한 VAD 알고리듬을 제안하였다. 임계값은 비음성 구간의 평균과 표준편차를 추산하여 설정하였다. TIMIT 음성과 NOISEX 잡음 데이터베이스를 사용한 실험 결과, 제안된 알고리듬이 기존의 대표적인 비교 대상 알고리듬보다 우수함을 보였다. 정확도는 SNR 10 dB부터 -10 dB까지 ROC (Receiver Operating Characteristics) 곡선을 사용하여 비교하였다.

• 한국임상수의학회지
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• 제19권3호
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• pp.312-315
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• 2002

질병에 이환된 개체로부터 이환되지 않은 개체를 구분하기 위해 사용되는 대부분의 진단검사는 판별의 기준점 (cut-off value)을 필요로 한다. ROC (receiver operating characteristic) 곡선은 이러한 목적으로 흔히 사용되고 있으며 진단의 기준점을 다양하게 변화시킬 때 진단검사의 정확도 (민감도와 특이도)를 제시해주는 지표로 활용되고 있다. 저자들은 수의학관련 연구자들이 이 방법을 효과적으로 사용할 수 있도록 EXCEL에 내장된 비쥬얼 베이직으로 binormal ROC 곡선의 최대우도비를 계산해주는 프로그램을 작성하였다. 방사선 분야의 자료와 미생물학 자료를 예제로 들어 이 프로그램의 활용성을 높이고자 하였고 이 분야에 관심이 있는 연구자는 저자에게 연락하여 이 프로그램을 얻을 수 있다.

• 대한의용생체공학회:의공학회지
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• 제19권1호
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• pp.1-8
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• 1998

X-선 유방영상에서 군집성 미세석회화는 유방암의 조기 검출에 중요한 징후로 이용된다. 본 논문은 X-선 유방영상에서 군집성 미세석회를 검출하여 그것의 위치를 표시하는 컴퓨터 보조 검출 방법을 제안한다. 제안된 검출방법의 구성도는 ROI9region of interest)선택, 필름흠제거, srdm(surrounding region dependence method), 분류기, 그리고 위치 표시로 구성되어 있다. SRDM은 이미 저자들에 의해 제안되었으며, 이것은 현재의 픽셀을 둘러싸고 있는 두 개의 영역에서의 2차 히스토그램에 근거한 통계적인 텍스처(texture)분석 방법이며 X-선 유방영상에서 군집성 미세석회화의 검출을 위해 제안되었다. 또한, 본 논문에서 제안된 필름흠 제거 필터의 효과는 ROC (receiver operating-characteristics) 분석에 의한 분류 성능 측면에서 평가되어진다. 정상조직(normal tissue)과 군집성 미세석회화를 포함한 조직을 분류하기 위해 3계층 backpropagation 신경망이 분류기로 이용되었다. 검출된 군집성 미세석회화의 위치와 적절한 표시를 함으로써 진단방사선의사에게 더 많은 주의를 상기시킬 수 있다

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.668-671
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• 2007

A numerical study was conducted on a simplified model of a high-temperature solar receiver which incorporates liquid-metal heat pipe. The objective of this paper is to compare the isothermal characteristics of the heat pipe receiver with the conventional receiver utilizing convection of molten salt as heat carrier. The solar receiver was assumed to be subject to a concentration ratio between 50 and 1,000 to supply high-temperature heat to a stirling engine for electric power generation. For simplicity of the analysis, a cylindrical geometry was assumed and typical dimensions were used based on available literature. The heat pipe had a shape of double-walled cavity and the working fluid was a sodium. The analysis was performed assuming that the radiation heat flux on the inner walls of the receiver was uniform, since the focus of this study was laid on the comparison of the conventional type and heat pipe type receiver. The results showed that the heat pipe type exhibited superior performance when the operating temperature becomes higher. In addition, to explore the advantage of the heat pipe receiver, the channel shape and dimensions should be adjusted to increase the heat transfer area between the wall and the heat trnasfer medium.

• 한국태양에너지학회 논문집
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• 제27권3호
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• pp.7-13
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• 2007

A Dish type solar concentrating system consists of a parabolic concentrator and a cavity receiver. In order to achieve high temperatures from solar energy, it is essential to efficiently reflect the solar rays in the concentrator and to minimize thermal losses in the cavity receiver. Improving the economical efficiency of a solar power system required the stirling unit to be operated continuously. For continuous operation of the stilting unit, the receiver must be continuously provided with thermal energy from solar as well as additional combustion heat. It is possible for a hybrid solar receiver system equipped with an additional combustion to be operated 24 hrs/day. A hybrid solar receiver was designed and manufactured for a total thermal load of 35 kW in the operating temperature range $700^{\circ}C$ to $800^{\circ}C$. The hybrid receiver system was tested in gas-only mode by gas-fired heat to investigate thermal characteristics at inclination angle varying from 0 deg to 30 deg(cavity facing down) and the aperture to cavity diameter ratios of 0(closed cavity) and 1.0(open cavity). This paper has been conducted to measure temperature distribution in cavity surface and to analyze thermal resistances, and the evaporation and condensation heat transfer coefficient in all cases(open and closed cavity).