• Journal of Internet Computing and Services
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• v.10 no.5
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• pp.127-133
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• 2009

This paper presents an approach to classify normal and epilepsy from electroencephalogram(EEG) using a neural network with weighted fuzzy membership functions(NEWFM). To extract input features used in NEWFM, wavelet transform is used in the first step. In the second step, the frequency distribution of signal and the amount of changes in frequency distribution are used for extracting twenty-four numbers of input features from coefficients and approximations produced by wavelet transform in the previous step. NEWFM classifies normal and epilepsy using twenty four numbers of input features, and then the accuracy rate is 98%.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.129-135
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• 2008

This paper presents a methodology to forecast KOSPI index by extracting fuzzy rules based on the neural network with weighted fuzzy membership functions (NEWFM) and the minimized number of input features using the distributed non-overlap area measurement method. NEWFM classifies upward and downward cases of KOSPI using the recent 32 days of CPPn,m (Current Price Position of day n for n-1 to n-m days) of KOSPI. The five most important input features among CPPn,m and 38 wavelet transformed coefficients produced by the recent 32 days of CPPn,m are selected by the non-overlap area distribution measurement method. For the data sets, from 1991 to 1998, the proposed method shows that the average of forecast rate is 67.62%.

• The Journal of the Korea Contents Association
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• v.12 no.2
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• pp.1-9
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• 2012

This paper presents an algorithm for depression diagnosis using the Neural Network with Weighted Fuzzy Membership functions (NEWFM) and heart rate variability (HRV). In the algorithm, 22 different features were initially extracted from the HRV signal by frequency domain, time domain, wavelet transformed, and Poincar$\acute{e}$ transformed feature extraction methods; of these 6 optimal features were selected by significance evaluation using Non-overlap Area Distribution Measurement (NADM) based on NEWFM. The proposed algorithm uses these 6 optimal features to diagnose depression with an accuracy of 95.83%.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.179-186
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• 2009

This paper presents an approach to classify normal and Ventricular Tachycardia/Ventricular Fibrillation(VT/VF) from the Creighton University Ventricular Tachyarrhythmia DataBase(CUDB) using the neural network with weighted fuzzy membership functions(NEWFM). In the first step, wavelet transform is used for producing input values which are used in the next step. In the second step, two numbers of input features are extracted by phase space reconstruction method and peak extraction method using coefficients produced by wavelet transform in the previous step. NEWFM classifies normal and VT/VF beats using two numbers of input features, and then the accuracy rate is 90.13%.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.2
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• pp.65-77
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• 1994

This paper presents a derailed application procedure of the linear quadratic(LQ) theory for a SWATH heave and pitch control. A time domain model of coupled, linear time-invariant second order differential equations is derived from the frequency response model with the frequency dependent added mass and damping approximated as constant values at the heave natural frequency. Wave exciting forces are modeled as a sum of sinusoids. A systematic selection procedure of state and control weighting matrices is presented to obtain good transient behavior and acceptable fin movement. The validity of this controller design process is throughly investigated by simulations both in time domain and frequency domain and singular value plots of transfer function matrices. The finally designed control system shows good overall performances revealing that the applicability of the present study is proved successful.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.435-435
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• 2023

최근 기후변화의 영향으로 상대적으로 좁은 국가면적이라 할 수 있는 국내에서도 가뭄과 홍수가 지역적으로 동시에 발생하는 등 자연재해에 의한 피해가 빈번해지고 있다. 이 중 가뭄은 타 풍수해에 비하여 일반적으로 장기간의 무강우에 의해 발현되고, 피해가 발생할 경우 생활용수, 농업용수, 공업용수 등 다양한 지역의 용수사용특성에 따라 피해가 집중 및 가중되는 특징을 지닌다. 본 연구에서는 지역별 가뭄피해도에 영향을 주는 영향인자의 민감도 분석을 실시하고 그 결과를 분석하였다. "가뭄 피해도"는 용수별 직간접 피해의 정도를 점수 또는 등급 등의 정량적으로 나타낸 것으로 정의된다. 우선, 국가가뭄정보통계집(2018-2020)에서 제시된 지역별 가뭄피해정보자료와 용수사용특성을 기반으로 군집분석을 실시한 문기훈(2022)의 연구모형을 기반으로 최근 발행된 2021년의 피해정보를 추가적으로 반영하여 군집분석을 실시하였다. 그리고 지역별 가뭄피해도 군집등급에 영향을 주는 과거 피해인자와 용수사용특성을 함수화하고, 지역별 불확실성을 반영한 민감도 분석을 실시하였다. 분석 결과 지역별 과거의 가뭄피해경험여부 및 용수사용특성의 변동에 따라 지역적 가뭄피해도 군집등급이 달라짐을 확인할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.91-102
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• 2020

This study constructed production frontiers of inputs and outputs in a sequential manner, measured inefficiencies by applying a non-radial sequential weighted Russell directional distance function to these frontiers, and analyzed Luenberg productivity indices and the contribution of each of input and output factor based on these distances. The results are as follows. First, the productivity of banks increased due to technical changes after the global financial crisis. Second, productivity growth decreased between 2009 and 2014 due to technical changes after the recession, as previous studies have shown that technology progressed before the global financial crisis but then largely decreased or remained the same thereafter. After 2014, the productivity of banks improved. This result may be due to both technology improvement after 10 years of stagnation and reduction of inputs and non-performing loans. Third, the 3.6% annual of productivity growth for 10 years was comprised of 1.77% household loans, 0.67% corporate loans, 0.98% manpower, 1.18% non-performing loans, -0.5% total deposits, and -1.25% securities. Finally, this study has limitations since it could not control risks such as capital structure and interest volatility.

• The Korean Journal of Applied Statistics
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• v.1 no.2
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• pp.34-44
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• 1987

In order to estimate the optimum fertilizer level for rice, a major food crop, the experimental results obtained from the fertilizer trials conducted at 642 experimental sites(farmers' fields) throughout the country for the period from 1976 to 1979 were examined. Since non-significant interactions among fertilizers have been ovserved from the past experiences, only thirteen treatments(combinations of fertilizer levels) for the experiments as given in the Table 1 were chosen such that simple response curves can be fitted with independent variables being N, $P_2O_5, and K_2O$. Weighted combining analysis of variance was also carried out for each type of paddy fields to test the significance of Treatments $\times$ Experimental sites interaction, and highly significant variability in response to treatments among experimental sites in the same type of paddy fields was observed in most types of fields. For the types of paddy fields where the treatments $\times$ experimental sites interaction was not significant, separate response curves for N, $P_2O_5, and K_2O$ were estimated on the basis of the mean yields of rice, and common values of the optimum levels of fertilizers were extimated thereform. When the interaction is significant, response curves were fitted for each experimental sites. The average fertilizer doses estimated for the types of paddy fields based on the individual sites are given in Tables 7-1 and 7-2.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.5
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• pp.482-490
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• 2008

For a coastal or harbor structure design, one of the most important environmental factors is the appropriate extreme highest tide level condition. Especially, the information of extreme highest tide level distribution is essential for reliability design. In this paper, 23 set of extreme highest tide level data obtained from National Oceanographic Research Institute(NORI) were analyzed for extreme highest tide levels. The probability distributions considered in this research were Generalized Extreme Value(GEV), Gumbel, and Weibull distribution. For each of these distributions, three parameter estimation methods, i.e. the method of moments, maximum likelihood and probability weighted moments, were applied. Chi-square and Kolmogorov-Smirnov goodness-offit tests were performed, and the assumed distribution was accepted at the confidence level 95%. Gumbel distribution which best fits to the 22 tidal station was selected as the most probable parent distribution, and optimally estimated parameters and extreme highest tide level with various return periods were presented. The extreme values of Incheon, Cheju, Yeosu, Pusan, and Mukho, which estimated by Shim et al.(1992) are lower than that of this result.

• The Korean Journal of Applied Statistics
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• v.22 no.3
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• pp.595-606
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• 2009

Two tests were introduced for comparing several survival functions with doubly interval-censored data and illustrated with data surveyed by Korean Cancer Prevention Study (Jee et al., 2005). The test which extended Kim et al. (2006)'s test to the doubly interval-censored data has an advantage over Sun (2006)'s test in terms of saving computation time because the proposed test only depends on the size of risk set, and also the proposed test is applicable to continuous failure time data as well as discrete failure time data unlike Sun's test. Comparing male with female groups on the incubation time of diabetes was highly different and the survival of female group was longer than that of male one. Regardless of gender, the difference in survival functions of four age groups was highly significant with p-value of less than 0.001. This trend was more remarkable for female group than for male one. Simulation results showed that the significance level of both tests was well controlled and the proposed test was better than Sun's test in terms of power.