• International Journal of Contents
• /
• 제8권4호
• /
• pp.56-63
• /
• 2012

In recent decades, analyzing the activities of human brain achieved some accomplishments by using the functional Magnetic Resonance Imaging (fMRI) technique. fMRI data provide a sequence of three-dimensional images related to human brain's activity which can be used to detect instantaneous cognitive states by applying machine learning methods. In this paper, we propose a new approach for distinguishing human's cognitive states such as "observing a picture" versus "reading a sentence" and "reading an affirmative sentence" versus "reading a negative sentence". Since fMRI data are high dimensional (about 100,000 features in each sample), extremely sparse and noisy, feature selection is a very important step for increasing classification accuracy and reducing processing time. We used the Fisher Discriminant Ratio to select the most powerful discriminative features from some Regions of Interest (ROIs). The experimental results showed that our approach achieved the best performance compared to other feature extraction methods with the average accuracy approximately 95.83% for the first study and 99.5% for the second study.

• Journal of Electrical Engineering and Technology
• /
• 제13권5호
• /
• pp.2125-2133
• /
• 2018

To achieve high performance speed regulation, a robust adaptive speed controller is proposed for the permanent magnet synchronous motor (PMSM) subject to parameter uncertainties and input saturations in this paper. A nonlinear adaptive control is introduced to compensate the PMSM speed tracking errors due to uncertainties, disturbances and control input saturation constraints. By combining the adaptive control and the nonlinear robust control based on the interconnection and damping assignment (IDA) strategy, a new robust adaptive control is designed for speed regulation of PMSM. Stability and robustness of the closed-loop control system involved with the constrained control inputs rather than unconstrained control inputs are validated. Simulations for PMSM control in the presence of uncertainties and saturations nonlinearities show that the proposed approach is effective to regulate speed, and the average tracking error using the proposed approach is at least 32% smaller than the compared methods.

• 한국안전학회지
• /
• 제31권3호
• /
• pp.136-142
• /
• 2016

This study deals with traffic accident of roundabout by collision type. In pursuing the above, this study gives particular attention to developing the appropriate models using Tobit model. The main results are as follows. First, three Tobit models (by collision type) which are statistically significant(their $R^2$ values are 0.858, 0.918 and 0.859) are developed. Second, t-test results show that there are no differences between the predicted and actual values. Finally, such the common variable as traffic volume, and such the specific variables as diameter of central island, the number of circulatory roadway, approach width and average of the number of approach are adopted in this study.

• 통합자연과학논문집
• /
• 제5권4호
• /
• pp.246-252
• /
• 2012

Multivariate cumulative sum (CUSUM) control charts for simultaneously monitoring both means and variances under multivariate normal process are investigated. Performances of multivariate CUSUM schemes are evaluated for matched fixed sampling interval (FSI) and variable sampling interval (VSI) features in terms of average time to signal (ATS), average number of samples to signal (ANSS). Multivariate Shewhart charts are also considered to compare the properties of multivariate CUSUM charts. Numerical results show that presented CUSUM charts are more efficient than the corresponding Shewhart chart for small or moderate shifts and VSI feature with two sampling intervals is more efficient than FSI feature. When small changes in the production process have occurred, CUSUM chart with small reference values will be recommended in terms of the time to signal.

• 제어로봇시스템학회논문지
• /
• 제22권8호
• /
• pp.650-655
• /
• 2016

In this paper, a novel RLS-based DOB (Recursive Least Squares Disturbance Observer) scheme is proposed to improve the performance of DOB for nominal model identification. A nominal model can be generally assumed to be a second order system in the form of a proper transfer function of an ARMA (Autoregressive Moving Average) model. The RLS algorithm for the model identification is proposed in association with DOB. Experimental studies of the balancing control of a one-wheel robot are conducted to demonstrate the feasibility of the proposed method. The performances between the conventional DOB scheme and the proposed scheme are compared.

• 한국농공학회논문집
• /
• 제64권4호
• /
• pp.11-20
• /
• 2022

Currently, the operation rule of agricultural reservoirs in case of drought events follows the drought forecast warning standard of agricultural water supply. However, it is difficult to preemptively manage drought in individual reservoirs because drought forecasting standards are set according to average reservoir storage ratio such as 70%, 60%, 50%, and 40%. The equal standards based on average water level across the country could not reflect the actual drought situation in the region. In this study, we proposed the improvement of drought operation rule for agricultural reservoirs based on the percentile approach using past water level of each reservoir. The percentile approach is applied to monitor drought conditions and determine drought criteria in the U.S. Drought Monitoring (USDM). We applied the drought operation rule to reservoir storage rate in extreme 2017 spring drought year, the one of the most climatologically driest spring seasons over the 1961-2021 period of record. We counted frequency of each drought criteria which are existing and developed operation rules to compare drought operation rule determining the actual drought conditions during 2016-2017. As a result of comparing the current standard and the percentile standard with SPI6, the percentile standard showed severe-level when SPI6 showed severe drought condition, but the current standard fell short of the results. Results can be used to improve the drought operation criteria of drought events that better reflects the actual drought conditions in agricultural reservoirs.

• 한국수학교육학회지시리즈A:수학교육
• /
• 제47권2호
• /
• pp.135-154
• /
• 2008

The purpose of this study is to help to improve the method of math teaching by analysing how learner-centered teaching method offsets mathematical creativity and mathematical disposition. For this purpose, research questions are established as follows; (1) Mathematical creativity between open-ended learning activity approach(OLAA) and general classroom-based instruction(GCI) shows any difference? (2) Mathematical disposition between OLAA and GCI shows any difference? The results obtained through this study were as follows: (1) There was significant difference between OLAA group and CCI group in mathematical creativity. This means that open-ended learning activity approach was generally more effective in improving mathematical creativity than general classroom-based instruction. (2) There was no significant difference between OLAA group and GCI group in mathematical disposition. But the average scores of mathematical disposition except mathematical confidence improved a little. So we can say that open-ended learning activity approach brought an positive influence on students' mathematical disposition. The results obtained in this study suggest that the OLAA can be used to cultivate the children's mathematical creativity and disposition. Therefore, I suggest that teachers should use the OLAA to improve the children's mathematical creativity and disposition.

• 한국산학기술학회논문지
• /
• 제17권8호
• /
• pp.127-132
• /
• 2016

본 연구의 목적은 농촌진흥청 국립원예특작과학원 감귤시험장이 2014년 최종선발을 마친 감귤(학명:Citrus unshiu) 하양조생(제감가-5호) 품종개발의 기술가치를 평가하는 것이다. 감귤신품종(하양조생) 개발의 기술가치 및 경제적 평가방법은 비용접근법(cost approach), 수익접근법((income approach), 시장접근법(market approach) 중에 수익접근법이 이용되었고, 순현재가치(NPV), 내부수익률(IRR), 편익/비용 비율(Benefit/Cost ratio)을 추정하였다. 이는 농업 R&D사업의 효율성과 실용성 제고를 위하여 이용될 수 있을 것이다. 분석결과에 따르면, 감귤신품종인 하양조생 개발에 따른 기술가치평가액은 할인율 수준에 따라 최소 1,094.5억 원(할인율 8%)에서 최대 1,950.4억 원(할인율 4%), 평균 1,453.8억 원(할인율 6%)으로 추정되었고, 내부수익율 IRR의 값은 51.4%로 본 연구에서 기본할인율로 이용된 6%(10년만기 국고채 할인율 3%와 리스크프리미엄 3%를 합친 것) 보다 매우 크고, 순현재가치(NPV)의 평균은 145,375백만원으로 영보다 훨씬 크며, B/C 비율도 최대(할인율 4%) 81.3에서 최소(할인율 8%) 46.1, 평균(할인율 6%) 60.9로 나타나 감귤 신품종 개발사업의 경제적 타당성은 매우 높은 것으로 평가된다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권8호
• /
• pp.3474-3497
• /
• 2016

Network Function Virtualization (NFV) and Software Defined Networking (SDN) are recently considered as very promising drivers of the evolution of existing middlebox services, which play intrinsic and fundamental roles in today's networks. To address the virtual service deployment issues that caused by introducing NFV or SDN to networks, this paper proposes an optimal solution by combining quantum genetic algorithm with cooperative game theory. Specifically, we first state the concrete content of the service deployment problem and describe the system framework based on the architecture of SDN. Second, for the service location placement sub-problem, an integer linear programming model is built, which aims at minimizing the network transport delay by selecting suitable service locations, and then a heuristic solution is designed based on the improved quantum genetic algorithm. Third, for the service amount placement sub-problem, we apply the rigorous cooperative game-theoretic approach to build the mathematical model, and implement a distributed algorithm corresponding to Nash bargaining solution. Finally, experimental results show that our proposed method can calculate automatically the optimized placement locations, which reduces 30% of the average traffic delay compared to that of the random placement scheme. Meanwhile, the service amount placement approach can achieve the performance that the average metric values of satisfaction degree and fairness index reach above 90%. And evaluation results demonstrate that our proposed mechanism has a comprehensive advantage for network application.

• 한국정보통신학회논문지
• /
• 제19권10호
• /
• pp.2481-2490
• /
• 2015

원개인의료정보(Personal Healthcare Record:PHR)의 문제점은 병원서버에서 관리되고 있는 것이다. 서버에 저장된 PHR 정보는 환자의 질병 및 치료 등 매우 민감한 정보를 포함하고 있기 때문에 환자의 프라이버시 보호가 보장되어야하고 PHR의 접근은 특성상 많은 그룹별 접근이 허용된다. 따라서 이 논문에서 제안하는 계층적 신원기반 암호화(HIDE)를 이용한 그룹서명을 통해 PHR 데이터의 프라이버시를 보장할 수 있다. 또한 그룹서명을 통해 계층별 접근그룹에서 사용할 수 있는 세션키를 생성한다. 생성한 세션키는 PHR 데이터의 안전한 송수신이 가능하다. 제안방법은 암호화를 위한 처리 효율성 측면에서 기존 공개키 기반 암호화 방식보다는 평균 80%, 아이디기반 암호화 방식보다는 평균 50%이상 높은 효율성을 갖는다.