• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.735-737
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• 2017

An Off grid or remote solar electric systems are an energy supply to our home or to our companies without the utility of Grid at all. Off grid solar systems are very important for those who live in remote locations especially for developing countries where getting the electric grid is extremely expensive, inconvenient or for those who doesn't need to pay a monthly bill with the electric bill in general. The main critical components of any solar power system or renewable energy harvesting systems are the energy storage systems and its charge controller system. Energy storage systems are the essential integral part of a solar energy harvesting system and in general for all renewable energy harvesting systems. To provide an optimal solution of both high power density and high energy density at the same time we have to use hybrid energy storage systems (HESS), that combine two or more energy storage technologies with complementary characteristics. In this present work, design and simulation we use two storage systems supercapacitor for high power density and lithium based battery for high energy density. Here the system incorporates fast-response supercapacitors to provide power to manage solar smoothing and uses a battery for load shifting. On this paper discuss that the total energy throughout of the battery is much reduced and the typical thermal stresses caused by high discharge rate responses are mitigated by integrating supercapacitors with the battery storage system. In addition of the above discussion the off grid solar electric energy harvesting presented in this research paper includes battery and supercapacitor management system, MPPT (maximum power point tracking) system and back/boost convertors. On this present work the entire model of off grid electric energy harvesting system and all other functional blocks of that system is implemented in MATLAB Simulink.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.215-216
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• 2014

This paper proposes a control algorithm for permanent magnet synchronous generator with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage offshore wind power system under unbalanced grid conditions. The proposed control algorithm particularly compensates for the unbalanced grid voltage at the point of common coupling in a collector bus of offshore wind power system. This control algorithm has been formulated based on the symmetrical components in positive and negative rotating synchronous reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power are described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of ac input current is injected to the point of common coupling in the proposed control strategy. The amplitude of negative sequential component is calculated to minimize the negative sequential component of grid voltage under the limitation of current capability in a voltage source converter. The proposed control algorithm makes it possible to provide a balanced voltage at the point of common coupling resulting in the generated power of high quality from offshore wind power system under unbalanced network conditions.

• Journal of Ship and Ocean Technology
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• 제3권2호
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• pp.1-16
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• 1999

The incompressible Reynolds-Averaged Navier-Stokes(RANS) equations are solved using the standard $\textsc{k}-\varepsilon$ turbulence model and a finite volume method(FVM)with an O-type grid system. The computed results for its performance test are in good agreement with the published experimental data. The present method is applied to the study on the leading edge radius of a hydrofoil section Calculated results suggest that the leading edge radius has some effects on cavitation performances of a 2-D foil. A natural leading edge radius for the NACA66 section is determined from this study.

• 대한기계학회논문집
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• 제18권3호
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• pp.653-661
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• 1994

In this paper the CSCM type upwind flux difference splitting Navier-Stokes method has been applied to study the ARL-SL19 supersonic/transonic compressor cascade flow. H-type grid was chosen for its simplicity in applying cyclic tridiagonal matrix algorithm along with conventional slip/no-slip boundary conditions. The thin-layer algebraic model of Baldwin-Lomax was employed for the calculation of turbulent flows. The test case inlet Mach No. was 1.612 and inlet/exit pressure ratio($P_2/P_1$) was 2.15. The results were compared with experimental results from current method were compared well in suction surface with the experiments and other computational results; however, not well in pressure surface. It might be due to the complex flowfields such as shock/boundary layer interaction, turbulence, and flow separation, etc. In the future, a proper turbulence modelling and adaptive grid system will be studied to improve the solution quality.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.393-398
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• 2002

This study shows the fatigue test results of experiment on the strengthened slabs, the probability analysis of the fatigue behavior is also presented. Static und fatigue tests were performed on bridge decks strengthened with fiber plastics(Carbon Fiber Sheet, Glass Fiber Sheet, Grid Type Carbon Fiber). In this study, to analyze the probabilistic distribution of the fatigue life, the Weibull distribution was adopted. The Weibull distribution coefficient is inferred from the S-N diagram and the number of repeated load. As the result analysis, as the stress level is higher, the fatigue limit of the strengthened bridge deck are similarly discovered but in the range of the fatigue limit, CG specimen that was strengthened with Grid Type Carbon was proved most effective of reinforcement.

• 전기학회논문지
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• 제62권5호
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• pp.632-638
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• 2013

In this study, we described voltage fluctuation characteristics of distribution line during starting and normal operation condition of the small hydro generators. Based on these theories, we scrutinized the starting and operating characteristics of induction generators installed in two small hydro power plants that is connected to the distribution line and researched necessary factors when selecting the generator type. The type of turbines and capacity of generators are different. One is below 1,000kW and the other is above 1,000kW. Two generators are tested during starting, and it acts as motor not generator at the instant that the machine is connected to the grid. After connecting to the grid, the machine rotates above synchronous speed before converting to the generator mode. Therefore the characteristic of the generator during starting is same as it of motor.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.63.1-63
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• 2001

At 3-D vision measuring, the camera calibration is necessary to calculate parameters accurately. Camera calibration was developed widely in two categories. One is that establishes reference points in space, and the other is that uses the grid type frame and statistical method. But, the former has difficult to setup reference points and the latter has low accuracy. In this paper we present an algorithm for camera calibration using perspective ratio of the grid type frame with different line widths. The advantage of this algorithm is that it can estimate position, pose and distance between camera and object ...

• 한국실내디자인학회논문집
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• 제23호
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• pp.139-147
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• 2000

The cultural identity of design is very critical in the modern society which is called the society of complex culture and multi-culture. In addition, adopting a traditional lattice-like pattern as a composition element of interior space is an effective way in the context of adding a traditional touch to the modern interior space. Meanwhile, in the process of applying Korean traditional lattices to modern interior space, some problems occurred: it has not been properly embodied; or it has been mistaken for those of China and Japan sharing similar culture with Korea. Thus, this study is designed to have precise knowledge of Korea, Chinese and Japanese traditional lattices. Besides, typical patterns of each nation's lattices are comparatively analyzed from the geometrical viewpoint, in a bid to pave the way for th modernization of traditional lattices. In particular, standards are set and proposed to identify different nations's lattices mainly focusing on grid type lattices which are often used and confusing.

• 한국전산유체공학회지
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• 제11권1호
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• pp.1-7
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• 2006

Numerical investigation of a centrifugal compressor volute having a modified straight conical duct hill been made. Three-dimensional Reynolds-Averaged Navier-Stokes equations with $k-{\varepsilon}$ turbulence equation are solved To avoid coordinate singularity at the central axis of the duct, multi-block H-type grid is generated on the circular cross-sections of the volute and stretched toward the solid wall boundary. We obtained numerical results with three different mass flow rates at the volute inlet, namely, with the inlet conditions that give small, medium and large mass flow rates at the outlet of the conical duct. Agreement with the experimental results is observed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.226-229
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• 2003

Increasing of the use nonlinear power electronics equipments, power conditioning systems have been researched and developed for many years to compensate the harmonic disturbances and the reactive power. The main function of power conditioning systems is to reduce harmonic distortions, since extensive surveys quantify the problems associated with electric networks having non-linear loads. The main function of power conditioner compensates the current instead of the voltage. Therefore the inverter used in power conditioner is mostly current controlled type. In this paper, the proposed current control algorithm is analysed and discussed about how to design the controller which can apply power conditioning operation for grid-connective PV power system. And also proposed control system. To verify the proposed current control algorithm, a comprehensive evaluation with theoretical analysis, simulation, experiment results is presented.