• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.1-6
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• 2012

Five smart grid projects was started with large scale at Jeju Island in South Korea from 2009, and smart-grid test-bed was started in Nov. 2010. The five projects are Smart Power Grid (SPG), Smart Renewable (SR), Smart Transportation (ST), Smart Place (SP) and Smart Electric Service (SES). Korea government constructed the smart grid public relations center at Nov. 2010 in Jeju Island and there will be continued the field operation and interface testing among five smart gird projects until May. 2013.

• Bulletin of the Korean Mathematical Society
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• v.51 no.4
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• pp.1087-1100
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• 2014

We present an accurate and efficient numerical method for solving the Black-Scholes equation. The method uses an adaptive grid technique which is based on a far-field boundary position and the Peclet condition. We present the algorithm for the automatic adaptive grid generation: First, we determine a priori suitable far-field boundary location using the mathematical model parameters. Second, generate the uniform fine grid around the non-smooth point of the payoff and a non-uniform grid in the remaining regions. Numerical tests are presented to demonstrate the accuracy and efficiency of the proposed method. The results show that the computational time is reduced substantially with the accuracy being maintained.

• The Journal of the Acoustical Society of Korea
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• v.31 no.4
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• pp.214-224
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• 2012

The objective of this paper is to design multichannel spherical loudspeaker array by considering various positioning methods such as Gaussian grid, Lebedev grid and packing method. For the spatial sound manipulation, which is to make desired sound field by controling multiple sound sources, the Kirchhoff- Helmholtz integral states that sound fields can be reproduced in terms of infinite control sources on the integral surface. But since we cannot control infinite number of sources for the implementation, we have to allocate finite number of sound sources which can approximately act as infinite number of sources. To manipulate sound field inside of a sphere (which is typical example of three dimensional array) by controlling sound sources on the surface, three methods of allocating sound sources, which are Gaussian grid, Lebedev grid and packing method, are reviewed. For each geometry, the performances of manipulation rendered by time-reversal operator and higher-order ambisonics are compared.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.11
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• pp.2497-2506
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• 2010

Smart power grid is targeting to improve grid operation by integrating existing power IT technologies in the jeju smart grid field test. Real-time two-way communication and interoperability in power grid are essential to smart power grid. Adopting smart grid will increase security vulnerabilities in power grid by increasing the number of wireless sensors and the chances of the external exposure of communication networks. In addition, hackers can cause chaos in the power grid system with eavesdropping and forgery attacks in communication networks. Smart power grid is one of the most important systems in deploying smart grid, and it is important to design security system systematically since smart grid can be seriously damaged when problem occurs. In this paper, local and global smart grid security standard and security vulnerabilities in power grid are reviewed, and 2 level smart grid service model is proposed.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.145-151
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• 1999

An Interactive grid generation program(KGRID) with graphical user interface(GUI) has been improved. KGRID works on the UNLX environment and GUI has been implemented with OSF/Motif and X Toolkit and the graphics language is Open GL for visualization of the 3D objects. It supports more convenient user environment to generate 2D and 3D multi-block structured grid systems. It provides various useful field grid generation methods, which are the algebraic methods, the elliptic partial differential equations method and the predictor-corrector method. It also supports 3D surface grid generation with NURBS(Non-Uniform Rational B-Spline) and various stretching functions to control grid points distribution on curves and surfaces. And some menus are added to perform flexible management, for the objects. We generated surface and field grid system about full aircraft configuration using KGRID. The performance and stability of the KGRID is verified through the generation of the grid system about a complex shape.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.1
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• pp.70-81
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• 1999

To predict the viscous boundary layers and wakes around a ship, the CFD techniques are commonly used. For the efficient application of CFD tools to practical hull farms, a 3-D field grid generating system is developed. The present grid generating system utilizes the solution of Poisson equation. Sorenson's method developed for 2-D is extended into 3-D to provide the forcing functions controling grid interval and orthogonality on hull surface, etc. The weighting function scheme is used for the discretization of the Poisson equation and the linear equations are solved by using MSIP salver. The trans-finite interpolation is also employed to assure the smooth transition into boundary surface grids. To rove the applicability, the field grid systems around a container ship and a VLCC with bow and stem bulb are illustrated, and the procedures for generating 3-D field grid system are explained.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1001-1006
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• 2012

This paper presents a carbon nanotube (CNT) triode-structure field emitter as an ion source in a micro time-of-flight mass spectrometer(TOF-MS). In the ion source by field emission, the electrons emitted from cathodes under an electric field accelerated to the anode and ionize gas molecules by impact before arriving the anode. The generated positive ions are to be accelerated to the ion collector. Whereas most of ions are drawn to the cathodes in diode field emitters, a grid in the triode field emitter prevents the ions from being drawn to the cathodes. The triode field emitter is fabricated by micromachining. The cathode is composed of six CNT cylinders. The total size of the fabricated device is $8.0{\times}7.3{\times}1.9mm^3$. The anode and the grid current of the fabricated CNT field emitter were measured for various anode and grid voltages. When the anode and the grid voltages are 1000 V and 990 V, respectively, the emission current passing through the ionization region is 8.6 ${\mu}A$, which is a sufficient emission current for ionization and mass spectrometry.

• Journal of the Korean Institute of Landscape Architecture
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• v.13 no.1
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• pp.123-130
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• 1985

In this study, the distribution of players on a soccer field was investigated with slide -photos in order to suggest a basic data for the athletic turf maintenance and construction. The results of this investigation may be summarized as follows. 1) There's a tendency that trampling frequency per grid (32.23m$^2$)of a soccer field gradually increases from the corner area to the center. Especially the area around goal and center-circle get the highest frequency. 2) Trampling numbers per grid show the similar tendency to trampling fequency. And the grid around the goal get the highest trampling number per grid.(6.52 times/32.23m$^2$). 3) The extent of the damage to the athletic turf per grid also show the similar tendency to the foregoing results. Under such extent of the damage to the athletic turf as these, the method of the turf maintenance and construction will be made.

• Journal of the Korean earth science society
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• v.23 no.1
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• pp.105-111
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• 2002

The observation of the new biotite isograd (chlorite + chloritoid = andalusite + biotite) in the Mungyong coal field requires the modification of Harte and Hudson's (1979) metapelite grid which eliminates the stability field of staurolite + cordierite assemblages. The newly proposed metapelite grid by Ahn and Nakamura (2000) can define more properly the isograd reaction observed from nature. We discuss first topological interrelations between synthetic system (FASHO-, KFASHO-, KFMASH system) on an isobaric section at 2kbar, where phase relations are well constrained. The following discussion is concentrated on the topological relations between stable reactions. At the last, we discuss the petrogenetic significance of the Ahn's petrogenetic grid compared with theoretically computed grids. Ahn's petrogenetic grid is consistent with synthetic and natural system, and is one of the excellent example of KFMASH approximation in metapelite.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.64-74
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• 1997

A CELTHYM(CEll-based Long-term HYdrologic Model), a pre-processor and a post-processor that can be integrated with geographic information system(GIS) were developed to predict the stream flow from the small agricultural watershed on the daily basis. The CELTHYM calculates the direct runoff from a grid using SCS curve number method and then sum up all of cells with respect to a sub-catchment area belonged to a stream grid and integrated to an outlet. Base flow of a watershed outlet was computed by integrating of the base flow of each stream grid that was averaged the sub-catchment deep-percolation and calculated with the release rate. Two kind of water budget equation were used to compute the water balance in a grid that was classified into not paddy field and paddy field. One of the two equation is a soil water balance equation to account the soil moisture of the upland, forest and excluding paddy field grid. The other is a paddy water balance equation for the paddy field, calculating the ponding depth, the effective rainfall, the deep percolation and the evapotranspiration.