• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.9
• /
• pp.2253-2260
• /
• 2009

The typical distribution systems have the power flow from distribution substations (sources) to customers (load) only as one direction. However, in the case where new energy power sources are connected to distribution systems, the output variations of new energy sources to distribution systems, which is so called reverse power flow, may cause the bi-directional power flow. So, the reverse power flow has severe impacts on typical power system, for example power quality problems, protection coordination problems, and so on. Therefore, this paper proposes the algorithm for Multi-functional protection devices in distribution systems in the case where new energy sources are interconnected. The proposed algorithm is verified to show the effectiveness by simulating and experimenting the prototype systems.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2019.10a
• /
• pp.581-584
• /
• 2019

Food consumption is growing worldwide every year owing to a growing population. Hence, the increasing population needs the production of sufficient and good quality food products. Strawberry is one of the world's most famous fruit. To obtain the highest strawberry output, we worked with three strawberry varieties supplied with three kinds of nutrient water in a greenhouse and with the outcome of the strawberry production, the highest yielding strawberry variety is detected. This Study uses the nutrient water consumed every day by the highest yielding strawberry variety. The atmospheric temperature, humidity and CO2 levels within the greenhouse are identified and used for the prediction, since the water consumption by any plant depends primarily on weather conditions. Machine learning techniques show successful outcomes in a multitude of issues including time series and regression issues. In this study, daily nutrient water consumption of strawberry plants is predicted using machine learning algorithms is proposed. Four Machine learning algorithms are used such as Linear Regression (LR), K nearest neighbour (KNN), Support Vector Machine with Radial Kernel (SVM) and Gradient Boosting Machine (GBM). Gradient Boosting System produces the best results.

• Journal of Power Electronics
• /
• v.17 no.6
• /
• pp.1658-1671
• /
• 2017

To address the inaccurate load demand sharing problems among parallel inverter-interfaced voltage-controlled distributed generation (DG) units in islanded microgrids (MGs) with different DG power ratings and mismatched feeder impedances, an enhanced voltage control scheme based on the active compensation of circulating voltage drops is proposed in this paper. Using the proposed strategy, reactive power and harmonic currents are shared accurately and proportionally without knowledge of the feeder impedances. Since the proposed local controller consists of two well-separated fundamental and harmonic voltage control branches, the reactive power and harmonic currents can be independently shared without having a remarkable effect on the amplitude or quality of the DGs voltage, even if nonlinear (harmonic) loads are directly connected at the output terminals of the units. In addition, accurate load sharing can also be attained when the plug-and-play performance of DGs and various loading conditions are applied to MGs. The effects of communication failures and latency on the performance of the proposed strategy are also explored. The design process of the proposed control system is presented in detail and comprehensive simulation studies on a three-phase MG are provided to validate the effectiveness of the proposed control method.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.10
• /
• pp.1000-1004
• /
• 2010

A large number of current language processing systems use a part-of-speech tagger for preprocessing. Most language processing systems required a tagger with the highest possible accuracy. Specially, the use of domain-specific advantages has become a hot issue in machine translation community to improve the translation quality. This paper addresses a method for customizing an HMM or LHMM based English tagger from general domain to specific domain. The proposed method is to semi-automatically customize the output and transition probabilities of HMM or LHMM using domain-specific raw corpus. Through the experiments customizing to Patent domain, our LHMM tagger adapted by the proposed method shows the word tagging accuracy of 98.87% and the sentence tagging accuracy of 78.5%. Also, compared with the general tagger, our tagger improved the word tagging accuracy of 2.24% (ERR: 66.4%) and the sentence tagging accuracy of 41.0% (ERR: 65.6%).

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.3
• /
• pp.83-90
• /
• 2010

Composite materials can be used economically and efficiently in civil engineering applications when standards and procedure for analysis, design, construction and quality control are to be established. Bridge systems, including the girders and cross-beams, and concrete decks behave as the specially orthotropic plates. For such systems with sections, boundary conditions other than Navier solution types, it is very difficult to obtain its analytical solution. To design the bridge made by the composite materials, cross-section was used as the form-core shape for economical reason and finite difference method was used for output of the stress value. The Tsai-Wu failure criterion for stress space is used. In this paper, the rate of tensile strength reduction due to increased size was considered. And also numerical study is made for these cases.

• Journal of the Institute of Convergence Signal Processing
• /
• v.7 no.4
• /
• pp.207-213
• /
• 2006

This paper presents the design and implementation of a video processor for the device of need TV-OUT function. The designed video processor satisfies the standard conditions of ITU-R(International Telecommunication Union-Radiocommunication) BT.470. Also, in order to apply various digital device, we concentrate upon hardware complexity. ITU-R BT.470 can be classified as NTSC, PAL or SECAM. NTSC and PAL use QAM(Quardarature Amplitude Modulation) to transmit color difference signals and SECAM uses FM(Frequency Modulation). FM must have antic-cloche filter but filter recommended by ITU-R BT.470 is not easy to design due to sharpness of the frequency response. So this paper proposes that the special quality of anti-cloche filter is transformed easy to design and the modulation method is modified to be identical with the result required at standard. The processor can control power consumption by output mode to apply portable digital devices. The proposed processor is experimentally demonstrated with ALTERA FPGA APEX20KE EP20K1000EBC652-3 device and SAMSUNG LCD-TV.

• Korean Journal of Remote Sensing
• /
• v.26 no.5
• /
• pp.537-547
• /
• 2010

The importance of vegetation in studies of global climate and biogeochemical cycles is well recognized. Especially. the FPAR (fraction of photosynthetically active radiation) is one of the important parameters in ecosystem productivity and carbon budget models. Therefore, accurate estimates of vegetation parameters are increasingly important in environmental impact assessment studies. In this study, optical FPAR using the Terra MODIS (MODerate resolution Imaging Spectroradiometer), SPOT VEGETATION and ECOCLIMAP data reproduced on the Korean peninsula. We applied the empirical method which is usually estimated as a linear or nonlinear function of vegetation indices. As results, we estimated the accurate expression which is 0.9039 of $R^2$ in cropland and 0.7901 of $R^2$ in forest. Finally, this study could be demonstrated to calibrate that produced FPAR while the overall pattern and random noise through the comparative analysis of FPAR on the reference data. Optimal use of input parameter on the Korean peninsula should be helping the accuracy of output as well as the improved quality of research.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.11
• /
• pp.71-78
• /
• 2019

Most 3D displays that are currently in the market adopt the binocular disparity method creating a different image for the left and right eye for a 3 dimensional effect. However, commercialized 3D image output devices lack in performance making it uncomfortable for the viewer and restrict the viewer to certain positions. In this paper, we propose a single-cell polarized lens type stereoscopic system which has a smaller viewing angle and reduced crosstalk, with improved light penetration compared to existing double-cell structures; and analyzed the single-cell polarized lens type stereoscopic system properties, and conducted an effect analysis of performance improvement compared to the dual-cell type. Results showed that the single-cell type had a 25% improved performance, and the 3D crosstalk index which is an important index for quality characteristics of stereoscopic systems, increased over about 37%, compared to the dual-cell type.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.5
• /
• pp.181-186
• /
• 2019

In order to reduce the fossil fuels consumed in conventional commercial independent diesel generators in the same environment as the island area, it is necessary to develop a photovoltaic system that will bear more than 40% of the independent system capacity. For this development, it is necessary to develop a high-capacity inverter that can improve the stability of the independent system installed in the island area and supply high-quality power to the load. In addition, the EMS power generation control system for the independent grid photovoltaic power generation system is a parallel operation power control system of the diesel generator connected with the solar power generation system. It controls the output of the diesel generator according to the load ratio and the solar power generation, A stable supply system is needed. This independent grid photovoltaic generation system can increase the solar power supply to the independent system area and increase the power stability of the independent system and further reduce the use of fossil fuel due to the ineffective power control of the independent system. It is expected that the economy will be secured early.

• Journal of the Korean Society for Railway
• /
• v.18 no.6
• /
• pp.533-542
• /
• 2015

This paper suggest away to maintain constant power through trolley wire by transferring increased line voltage to the AC main line while changing the mode from Converter(Forward) to Inverter(Reverse) when the line voltage is increased due to regenerative power when the train stops, This paper suggests a Double Converter DC substation that can create regenerative power when the train stops reusable. We also proposed using a simulation tool, the optimal Thyrister firing angle that can minimize the undershoot and overshoot that occurs when transferring the mode from Converter to Inverter for quality improvement of DC voltage in the Double Converter in the DC substation from the Busan Urban Subway.