• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.992-993
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• 2006

본 논문에서는 계통연계형 인버터에서 요구되는 전력품질 개선 기능, 부하수요관리 기능, 무정전전원공급 기능 등을 전류제어형 전압원 인버터 시스템에서 통합적으로 수행할 수 있는 UPS를 고려한 계통연계형 전류제어 인버터를 제안한다. 제안된 시스템은 평상시에는 무효전력 보상, 고조파 저감, 부하수요관리 등의 PCS(Power Conditioning System) 기능을 수행하고 계통 고장시에는 배터리에 저장된 에너지를 이용하여 부하에 즉시 정전압을 공급하는 UPS 기능을 수행한다. 본 연구에서는 제안된 시스템의 동작원리 및 제어 알고리즘을 이론적으로 해석하고 시뮬레이션을 통하여 유용성을 확인한다.

• Proceedings of the Safety Management and Science Conference
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• 2009.11a
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• pp.411-415
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• 2009

There are some definitions of cloud computing but it can be defined as utilization of personal computers, servers and softwares in one cluster for approaches to the use of shared computing resources. Nowadays the applications of cloud computing are rapidly increasing because of its merits on economic aspect, connectivity convenience, storage space and so on. The main objective of this paper is to find an effective methodology as an initial stage for applications of cloud computing in a real life. Therefore this paper addresses worldwide reviews on cloud computing.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.91-93
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• 2008

In this paper, novel phase angle following algorithm for the single phase grid-connected inverter is proposed. Gird-connected inverter needs phase angle detection for synchronization grid voltage with the inverter output. In case of single phase grid-connected inverter, zero crossing detection and virtual 2-phase PLL using digital all pass filter or digital low pass filter are used conventionally. But these methods have a weakness for harmonics, noises and ripples. The proposed method of PLL achieve DFT(Discrete Fourier Transform) using Goertzel algorithm. It can extract fundamental voltage of grid. As a results, it can obtain phase angle using digital all pass filter without effect of harmonics, noises and ripples. Simulation results are presented to demonstrate the effectiveness of the proposed algorithm.

• The Journal of Korea Robotics Society
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• v.2 no.3
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• pp.227-233
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• 2007

Representing an environment as the probabilistic grids is effective to sense outlines of the environment in the mobile robot area. Outlines of an environment can be expressed factually by using the probabilistic grids especially if sonar sensors would be supposed to build an environment map. However, the difficult problem of a sonar such as a specular reflection phenomenon should be overcome to build a grid map through sonar observations. In this paper, the NRF(Neighborhood Recognition Factor) was developed for building a grid map in which the specular reflection effect is minimized. Also the reproduction rate of the gird map built by using NRF was analyzed with respect to a true map. The experiment was conducted in a home environment to verify the proposed technique.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.11
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• pp.1004-1011
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• 2000

Experimental and computational studies were carried out to confirm the turbulent enhancement of the cooling system of nuclear reactor by large scale vortex generation in nuclear fuel bundle. The large scale vortex motions were generated by rearranging the inclination angles of mixing vanes to the coordinate directions. Axial development of mean and turbulent velocities in the subchannels were measured by the 2-color LDV system. Eddy diffusivity heat flux model and $k-varepsilon$ model were employed to analyze the turbulent heat and fluid flows in the subchannel. The turbulence generated by split mixing vanes has small length scales so that they maintain only about $10 D_H$ after the spacer grid. On the other hand, the turbulences generated by the large scale vortex continue more and remain up to $25 D_H$after the spacer gird.

• Journal of Ocean Engineering and Technology
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• v.14 no.1
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• pp.52-59
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• 2000

Flexural fracture characteristics of newly-developed Grid-type carbon fiber plastics in the deteriorated reinforced concrete structures were investigated by the four-points fracture test to verify the strengthening effects in the beam specimens. Results showed that initial cracks appeared in the boundary layers of fibers embedded in the newly-placed mortar concrete slowly progressed to the direction of supports and showed fracture of fiber plastics and brittle failure of concrete in compression in sequence after the yielding of steel reinforcement. Accordingly the reasonable area of Grid-type carbon-fiber plastics in the strengthening design of deteriorated RC structures should be limited and given based on the ultimate strength design method to avoid the brittle failure of concrete structures.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.31-33
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• 1999

In this paper, a operating characteristics of the 50 kW grid-connected Photovoltaic(PV) Power system which is by means of initial PV datum analyzing is reported. The development of a 50 kW class photovoltaic power generation system including a DC/AC inverter is suggested to investigate the system performance for grid connection. The results of the demonstration test of a 50 kW class grid-connected PV system show that the system utilization rate is 15.6% and the inverter efficiency is 94% at 80% load.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.43-48
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• 2003

When the Eulerian-Lagrangian method is used to analyze the particle laden two-phase flow, a large number of particles should be used to obtain statistically meaningful solutions. Then it takes too much time to track the particles and to average the particle properties in the numerical analysis of two-phase flow. The purpose of this paper is to reduce the computation time by means of a set of particle gird separate to the flow grid. Particle motion equation here is the simplified B-B-O equation, which is integrated to get the particle trajectories. Particle turbulent dispersion, wall collision, and wall roughness effects are considered but the two-way coupling effects between gas and particles are neglected. Particle laden 2-D channel flow is solved and it is shown that the computational efficiency is indeed improved by using the current method

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.187-192
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• 1999

Noncontact measuring methodology of 3-dimensional profile using CCD camera are very attractive because of it's high measuring speed and its's high sensitivity. Especially when projecting a grid pattern over the object, the captured image have 3 dimensional information of the object. Projection moire extract 3-D information with another grid pattern in front of CCD camera. However phase measuring profilometry(PMP) obtain similar results without additional grid pattern. In this paper, the projection moire are compared with the PMP mathematically, and it is shown that PMP can generate moire image with simple mathematical computations. Experimental works are also carried out showing the same results. It is shown that using a single gird pattern, moire image can be obtained directly without any mathematical operation when some conditions are satisfied.

• Journal of the Korean Home Economics Association
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• v.30 no.4
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• pp.1-13
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• 1992

A computer simulation method for textile designs was developed using a generic-purpose graphics program, LUMENA and its results were applied for costume design simulation. Its design performance was comparable with those using specialized design package programs which are in general very expensive. Three areas of textile design, print pattern design, weaving design, and knitting design, were covered. In the print pattern design simulation, a gird network library was constructed by using basic methods of repeat, and a pattern library by scanning existing print patterns. Through the modification and synthesis of library patterns, many new print patterns could be obtained. In the weaving design simulation, a thread library and a draw-down library were constructed. Using them, simulations of woven textile structures were carried out. In the knitting design simulation, a stitch library and a detail library were made from various types of knit stitch and detail drawings of knit costume, respectively. They were used to make structural knitting patterns and jacquard knitting designs. Using those simulated textile designs, costume design simulation was carried out.