• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.696-704
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• 2013

In this paper, we introduce the LED emotional lighting system realized with the aid of both intelligent algorithm and RGB LED combined with White LED. Generally, the illumination is known as a design factor to form the living place that affects human's emotion and action in the light- space as well as the purpose to light up the specific space. The LED emotional lighting system that can express emotional atmosphere as well as control the quantity of light is designed by using both RGB LED to form the emotional mood and W LED to get sufficient amount of light. RBFNNs is used as the intelligent algorithm and the network model designed with the aid of LED control parameters (viz. color coordinates (x and y) related to color temperature, and lux as inputs, RGBW current as output) plays an important role to build up the LED emotional lighting system for obtaining appropriate color space. Unlike conventional RBFNNs, Fuzzy C-Means(FCM) clustering method is used to obtain the fitness values of the receptive function, and the connection weights of the consequence part of networks are expressed by polynomial functions. Also, the parameters of RBFNN model are optimized by using PSO(Particle Swarm Optimization). The proposed LED emotional lighting can save the energy by using the LED light source and improve the ability to work as well as to learn by making an adequate mood under diverse surrounding conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.5
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• pp.833-842
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• 2017

In this study, the design methodology of radial basis function neural networks based on incremental K-means clustering is introduced for learning and processing the big data. If there is a lot of dataset to be trained, general clustering may not learn dataset due to the lack of memory capacity. However, the on-line processing of big data could be effectively realized through the parameters operation of recursive least square estimation as well as the sequential operation of incremental clustering algorithm. Radial basis function neural networks consist of condition part, conclusion part and aggregation part. In the condition part, incremental K-means clustering algorithms is used tweights of the conclusion part are given as linear function and parameters are calculated using recursive least squareo get the center points of data and find the fitness using gaussian function as the activation function. Connection s estimation. In the aggregation part, a final output is obtained by center of gravity method. Using machine learning data, performance index are shown and compared with other models. Also, the performance of the incremental K-means clustering based-RBFNNs is carried out by using PSO. This study demonstrates that the proposed model shows the superiority of algorithmic design from the viewpoint of on-line processing for big data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.977-985
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• 2012

Performance optimization of a small engine intake port has been studied through computational and experimental approach. Port angle, flange area and port shape are very important design parameters affecting performance of an intake port. Especially, radius of curvature of intake port inner surface has major effect on the flow coefficient of an intake port. As increasing port angle and flange area, flow coefficient is increased because pressure distribution and pressure gradient in the intake port are improved. Even though computational results over-predict maximum 8% compared with experimental result, they describe the tendency of flow coefficient according to the design parameters. Optimized intake port shows about 4.5% improved flow performance.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.11-17
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• 2000

Optimum parameters were investigated for the simultanious analysis of 24 pesticide residuces using gas-liquid chromatography with electron capture detection. Electronic pressure control(EPC) on column enhanced resolution of 24 analyzes. Using DB-17, SPB-608, and Ultra-2 capillary column without EPC incomplete separation was observed in some pairs of pesticides. When EPC function was adopted, no severe overlapping was observed on SPB-608 column in every pesticides except vinclozolin/acetochlor pair. Total running time was 45 min, much shorter than $69{\sim}81$ min when used without EPC. Limit of determination of each analyze ranged $0.1{\sim}12.9$ ng/mL.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5A
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• pp.493-500
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• 2006

This paper presents the efficient structure and parameter optimization of downlink beamforming transmitter in OFDMA/TDD system. To design downlink beamforming transmitter for multiple transmit antennas, an efficient beamforming structure for multiple users and the choice of word-length of each block are critical in the aspect of its performance and hardware complexity. We propose an efficient beamforming scheme, which stores the weights of subcarriers into memory without user identification at the receiver of base station and calculates the weights for corresponding user in a subcarrier unit of IFFT input at high speed. Also, we obtain the word-length of main data path and other design parameters by fixed-point simulation analysis. The proposed architecture could reduce the memory size proportional to the maximum number of users per frame, and the processing time of an OFDM symbol at the receiver of base station without the need of additional processing time for calculating the weights at the transmitter.

• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.11-24
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• 2018

The purpose of the present study is to develop an analysis model to analyze the design parameter sensitivity of a high-power drifter suitable for implementation in Korean hydraulic drills. This study aims to establish a basis for the optimization of the impact performance and stability of a high-power drifter by investigating the effects of each design parameter on the impact performance via design parameter sensitivity analysis. To begin, an analysis model of drifter dynamics is developed, and the reliability of the analysis model is verified by comparing the analysis results to the experimental results. The drifter is then redesigned for compatibility with Korean hydraulic drills. Finally, design parameter sensitivity analysis of the redesigned drifter is conducted to determine the effects of the design parameters on the impact performance, and to extract the high-sensitivity parameters. SimulationX, which is multi-physics analysis software, is used to develop the analysis model, and EasyDesign is employed for design parameter sensitivity analysis.

• Journal of Welding and Joining
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• v.27 no.3
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• pp.38-43
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• 2009

The optimization of the welding parameters was studied to maximize the weldability and minimize the amount of spatter in the MAG welding of automotive steel sheets under different shielding gas composition ratio. JS-EFSC, JS-SPHC steel plates and Ar mixture gases were used as a substrate and shielding gas for welding respectively. The five welding parameters were selected through preliminary experiments and their effects on the weldability were analyzed. Experiments were performed using the Taguchi experimental method. As results, appropriate range for welding could be achieved. Amount of spatter in 80%Ar+20%$CO_2$ shielding gas was 20% of that of $CO_2$welding. Therefore, in terms of high productivity and welding cost, Ar mixture gas(80%Ar+20%$CO_2$) was recommended as a shielding gas for application of MAG process, indicating the low spatter and good weld quality.

• Journal of Korea Water Resources Association
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• v.38 no.9 s.158
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• pp.713-725
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• 2005

The objective of this study is to evaluate the applicability and simulation capability of PRMS, developed by U.S. Geological Survey, over the seven multi-purpose dam watersheds in Korea. The basic concepts of model components and their parameters are investigated for the evaluation of model applicability and the possibility of model parameter estimation is suggested based on the data availibility. For model parameter estimation, some parameters are directly estimated from measurable basin characteristics, but the others are estimated by Rosenbrock's automatic optimization scheme. The results show that the simulated flows from the model were very close to the observed ones. Although the default values for snowmelt model parameter are used, the results from snowmelt simulation is also acceptable. The model shows that the simulation capability is not sensitive to the basin size, however, according to increasing basin area, simulation characteristics are close to those for lumped model rather than semi-distributed model.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.11
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• pp.937-946
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• 2014

This paper presents system identification of a single tilt wing UAV. A Modified Equation Error Method(MEEM) and Extended Kalman Filter(EKF) are used for the identification of a single tilt wing UAV system in frequency-domain and time-domain, respectively. Simulated flight data is obtained from CNUX-3's vertical mode linear simulation with realistic sensor noise. System identification performance is analyzed with respect to a variety of design parameters of the MEEM. Also, High accuracy Fourier Transform(HFT) is applied to enhance the performance of MEEM. The results of the MEEM is compared with those of the EKF. Design parameters of the MEEM and initial conditions of the EKF are decided from optimization.

• Advances in Energy Research
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• v.4 no.1
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• pp.69-86
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• 2016

The quest to reduce the level of overdependence on fossil fuel product and to provide all required information on proven existing alternatives for renewable energy has resulted into rapid growth of research globally to identify efficient alternative renewable energy sources and the process technologies that are sustainable and environmentally friendly. The present study is aimed at production and characterization of bioethanol produced from sugarcane juice using a $2^4$ factorial design investigating the effect of four parameters (reaction temperature, time, concentration of bacteria used and amount of substrate). The optimum bioethanol yield of 19.3% was achieved at a reaction temperature of $30^{\circ}C$, time of 72 hours, yeast concentration of 2 g and 300 g concentration of substrate (sugarcane juice). The result of statistical analysis of variance shows that the concentration of yeast had the highest effect of 7.325 and % contribution of 82.72% while the substrate concentration had the lowest effect and % contribution of -0.25 and 0.096% respectively. The bioethanol produced was then characterized for some fuel properties such as flash point, specific gravity, cloud point, pour point, sulphur content, acidity, density and kinematic viscosity. The results of bioethanol characterization conform to American society for testing and materials (ASTM) standard. Hence, sugarcane juice is a good and sustainable feedstock for bioethanol production in Nigeria owing relative abundance, cheap source of supply and available land for large scale production.