• 전기학회논문지
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• 제58권9호
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• pp.1769-1774
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• 2009

An algorithm for extracting the BJT DC model parameter values for SPICE model is proposed. The nonlinear optimization method for analyzing the device I-V data using the Levenberg-Marquardt algorithm is proposed and the method for calculating initial conditions of model parameters to improve the convergence characteristics is proposed. The base current and collector current obtained from the proposed method shows the root mean square error of 6.04% compared with the measured data of the PNP BJT named 2SA1980.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.936-940
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• 2012

충분한 선행시간을 확보한 강우의 정확한 예측은 홍수피해를 저감하기 위한 필요한 조건이다. 이를 위해 지역규모의 기상모델인 Advanced Research WRF (ARW)를 적용하여 지역에 맞는 강우 예측에 가장 밀접한 관계를 갖는 물리학적 요소들의 최적화된 조건을 찾아보려 한다. 이를 위해 2006년의 7월의 강우에 대한 분석을 실시하고 생극과 분천의 강우 관측치 와의 비교를 통해 (Root Mean Square Error와 Index of Agreement 활용), ARW의 수문학적 예측을 위한 적용 가능성을 보려 한다.

• 산업경영시스템학회지
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• 제23권54호
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• pp.119-128
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• 2000

This study develops the pay satisfaction questionnaire for Korean employees. Based upon the review of previous studies, 16 questionnaire items are developed. Exploratory factor analysis results in a modified measurement through item deletion, item-to-dimension reassignment, and dimension combination. The measurement model was good fit assessed by overall fit measures(GFI; goodness of fit index, AGFI; adjusted goodness of fit index, RMR; root mean square residual) criteria, lambda score, and squared multiple correlation with confirmatory factor analysis. Implication of this work for future theoretical and empirical development are suggested.

• Ocean Systems Engineering
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• 제8권4호
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• pp.361-380
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• 2018

The dynamic performance of the wave energy converter (WEC) rotor with different geometric parameters such as depth of submergence and beak angle has been assessed by considering the linear potential flow theory using WAMIT solver and along with the computational fluid dynamics (CFD). The effect of viscous damping is incorporated by conducting numerical free decay test using CFD. The hydrodynamic coefficients obtained from the WAMIT, viscous damping from the CFD and estimated PTO damping are used to solve the equation of motion to obtain the final pitch response, mean optimal power and capture width. The viscous damping is almost 0.9 to 4.6 times when compared to the actual damping. It is observed that by neglecting the viscous damping the pitch response and power are overestimated when compared to the without viscous damping. The performance of the pitch WEC rotor in the Jeju western coast at the Chagwido is analyzed using Joint North Sea Wave Project (JONSWAP) spectrum and square-root of average extracted power is obtained. The performance of WEC rotor with depth of submergence 2.8 m and beak angle $60^{\circ}$ found to be good compared to the other rotors.

• Communications for Statistical Applications and Methods
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• 제31권3호
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• pp.309-322
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• 2024

Identifying algae in water is important for managing algal blooms which have great impact on drinking water supply systems. There have been various microscopic approaches developed for algae classification. Many of them are based on the morphological features of algae. However, there have seldom been mathematical frameworks for comparing the shape of algae, represented as a planar continuous curve obtained from an image. In this work, we describe a recent framework for computing shape distance between two different algae based on the elastic metric and a novel functional representation called the square root velocity function (SRVF). We further introduce statistical procedures for multiple shapes of algae including computing the sample mean, the sample covariance, and performing the principal component analysis (PCA). Based on the shape distance, we classify six algal species in watersheds experiencing algal blooms, including three cyanobacteria (Microcystis, Oscillatoria, and Anabaena), two diatoms (Fragilaria and Synedra), and one green algae (Pediastrum). We provide and compare the classification performance of various distance-based and model-based methods. We additionally compare elastic shape distance to non-elastic distance using the nearest neighbor classifiers.

• 대한원격탐사학회지
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• 제39권6_2호
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• pp.1605-1613
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• 2023

해양 내의 다양한 물리적 변화는 수온과 염분의 지속적인 변동에 의해 결정된다. 수온과 더불어 넓은 영역의 염분 변화를 파악하기 위해서는 인공위성 자료에 의존할 수밖에 없다. 그럼에도 불구하고 염분을 관측하는 위성인 Soil Moisture Active Passive (SMAP)는 낮은 시·공간 해상도로 인해 연안 근처에서 빠르게 변화하는 해양환경을 관측하기에는 어렵다는 한계가 존재한다. 이러한 한계를 극복하기 위해 본 연구에서는 천리안 해양 관측 위성의 정지궤도 해색 센서인 Geostationary Ocean Color Imager-II (GOCI-II) 원격반사도 자료를 입력자료로 하여 고해상도 표층 염분을 산출하는 Multi-layer Perceptron Neural Network (MPNN) 기반의 알고리즘을 개발하였다. SMAP과 비교한 결과 coefficient of determination (R²)는 0.94, root mean square error (RMSE)는 0.58 psu 그리고 relative root mean square error (RRMSE)는 1.87%였으며, 공간적인 분포 또한 매우 유사한 결과를 나타냈다. R²의 공간 분포는 0.8 이상을 보여주었으며 RMSE는 전반적으로 1 psu 이하의 낮은 값을 보여주었다. 이어도 과학기지에서의 실측 염분값과도 비교하였지만 상대적으로 조금 낮은 결과를 보여주었다. 이에 대한 원인을 분석하였으며, 산출된 GOCI-II 기반 고해상도 염분 자료를 활용하여 2022년 11호 태풍 힌남노에 의한 하루 동안의 동중국해 표층 염분 변화를 표준편차로 계산하였다. 그 결과 SMAP에서 관측할 수 없는 시공간의 염분 변화를 고해상도의 GOCI-II 기반 염분 산출물을 통해 확인할 수 있었다. 따라서 본 연구를 통해 시간 단위로 변화하는 해양환경 모니터링에 큰 기여를 할 것으로 기대된다.

• 대한치과교정학회지
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• 제41권2호
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• pp.112-120
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• 2011

Objective: Microscrew implants (MSls) offer many advantages, but some complications are known to occur during their insertion. One of the most commonly reported complications is root injury. Our aim was to identify factors associated with root injury and to evaluate their qualitative and quantitative values. Methods: Thirty-five orthodontists placed MSls (AbsoAnchor$AbsoAnchor^{(R)}$, Dentos Co. Ltd, Daegu, Korea) in the upper jaw of typodonts, labially between the second premolar and the first molar, in low and high vertical positions. Root contacts were counted, and distances between MSI apices and roots were measured. Fear level of the orthodontists was surveyed before and after the experiment. Wilcoxon's test, chi-square test, and Mann-Whitney test were used for statistical analysis. Results: Overall root contact rate of MSI insertion was 23.57%. The root contact rate was significantly higher in MSls inserted at $90^{\circ}$ (45.71%) than at $30^{\circ}$ (1.43%). The distance between the dental root and MSI also increased significantly in MSls inserted at $30^{\circ}$. Mean fear level before MSI insertion (4.6) significantly decreased after insertion (3.2); the causative factors were risk of injury to dental root and maxillary sinus or mandibular canal. Conclusions: Root injury is relatively rare, and oblique angulation reduces the risk of root and MSI contact.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1338-1341
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• 2002

The Weibull probability density function and the Rayleigh function are compared by analyzing the relations of the capacity factors which are compared the actual wind speed frequency curve with which are modelled using the probability density functions with different mean wind speeds. For this analysis, the wind speed means of arithmetic, root mean square, cubic mean cuberoot, and standard deviations are computed from the measured wind speed data of a specific site and the coefficients of probability density functions are calculated. The capacity factors for Vestas 850[kW] wind turbine are calculated and analyzed. The results shows that the wind speed frequency curve by Rayleigh function is more close to the actual curve than by Weibull function. The more the wind speed frequency curve is close to the actual one, the more the capacity factors become large values.

• 농업과학연구
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• 제38권1호
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• pp.129-143
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• 2011

In this study, to select the incoming solar radiation equation which is most suitable for the estimation of Penman evaporation, 12 incoming solar radiation equations were selected. The Penman evaporation rates were estimated using 12 selected incoming solar radiation equations, and the estimated Penman evaporation rates were compared with measured pan evaporation rates. The monthly average daily meteorological data measured from 17 meteorological stations (춘천, 강능, 서울, 인천, 수원, 서산, 청주, 대전, 추풍령, 포항, 대구, 전주, 광주, 부산, 목포, 제주, 진주) were used for this study. To evaluate the reliability of estimated evaporation rates, mean absolute bias error(MABE), root mean square error(RMSE), mean percentage error(MPE) and Nash-Sutcliffe equation were applied. The study results indicate that to estimate pan evaporation using Penman evaporation equation, incoming solar radiation equation using meteorological data such as precipitation, minimum air temperature, sunshine duration, possible duration of sunshine, and extraterrestrial radiation are most suitable for 11 study stations out of 17 study stations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.682-685
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• 2004

This paper investigated a method for classifying emotional states by using pulse wave signal. It focused on finding effective features for emotional state classification. The emptional states considered here consisted of interest and neutral. Classification experiments utilized 65 and 60 samples of interest and neutral states respectively. We have investigated 19 features derived from pulse wave signals by using both time domain and frequency domain analysis methods with 2 classifiers of minimum distance (normalized Euclidean distanece) and ${\kappa}$-Nearest Neighbour. The Leave-one-out cross validation was used as an evaluation mehtod. Based on experimental results, the most efficient features were a combination of 4 features consisting of (i) the mean of the first differences of the smoothed pulse rate time series signal, (ii) the mean of absolute values of the second differences of thel normalized interbeat intervals, (iii) the root mean square successive difference, and (iv) the power in high frequency range in normalized unit, which provided 80.8% average accuracy with ${\kappa}$-Nearest Neighbour classifier.