• Journal of the Korean Applied Science and Technology
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• v.25 no.4
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• pp.518-524
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• 2008

In this study, positive plates of lead acid battery of Pb-Ca alloy and Pb-Ca-Sn alloy were fabricated and the mechanical characteristics of positive plates were measured. This study observed how the changes of content of Ca & Sn affect interface corrosion which is located in between grid & active materials and lead acid batteries as well. The mechanical characteristics of grid alloy is better when Ca is 0.05 wt.% then 0.1 wt.%. This study said that the corrosion rate between the active material based on the charge/discharge cycle of lead acid battery and grid interface is much faster than a grid which contains Sn. And furthermore, according to the study the rate 30 of Sn/Ca which is added to grid shows the best performance.

• Journal of Power Electronics
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• v.18 no.1
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• pp.171-184
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• 2018

Unbalanced and distorted grid voltages cause the grid side current of a current source PWM rectifier to be heavily distorted. They can also cause the DC-link current to fluctuate with a huge amplitude. In order to enhance the performance of a current-source PWM rectifier under unbalanced and harmonic grid voltage conditions, a mathematical model of a current-source PWM rectifier is established and a flexible multi-objective control strategy is proposed to control the DC-link current and grid-current. The fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic components of the grid voltage are first separated with the proposed control strategy. The grid current reference are optimized based on three objectives: 1) sinusoidal and symmetrical grid current, 2) sinusoidal grid current and elimination of the DC-current $2^{nd}$ order fluctuations, and 3) elimination of the DC-current $2^{nd}$ and $6^{th}$ order fluctuations. To avoid separation of the grid current components, a multi-frequency proportional-resonant controller is applied to control the fundamental positive/negative sequence, $5^{th}$ and $7^{th}$ order harmonic current. Finally, experimental results verify the effectiveness of proposed control strategy.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.66-69
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• 2002

This article outlines the capabilities of a viewer component called GridViewer, and proves its reusability. GridViewer was designed for the construction of the image display part of GIS or remote sensing application software, and consequently it is particularly straightforward to closely couple GridViewer with access to very large images. Displaying is performed through pyramid structure, which enables to treat very large dataset up to several gigabytes in size under the limited capability of PC. GridViewer is free from responsibility to handle various formats of raster data files by taking grid coverage, which is designed by OGC to promote interoperability between implementations done by data vendors and software vendors providing analysis and grid processing implementations. GridViewer differs from other such viewer by allowing for clients to extend its function and capability by using small set of methods originally implemented in it. We show its reusability and expandability by applying it in developing application programs performing various functions not supported originally by the GridViewer COM component.

• International Journal of CAD/CAM
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• v.8 no.1
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• pp.63-67
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• 2009

This paper puts forward a method based on the boundary deformation for planar grid generation. Many methods start with the special properties of grid and switch to the solution of a direct optimization or a non-linear minimum cost flow. Though with high theoretical significance, it's hard to realize due to the extremely complicated computing process. This paper brings out the automatic generation of planar grid by studying the boundary deformational properties of planar grid, which leads to uniform grid and enjoys the simplicity of computation and realization.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.71-74
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• 2011

2030년까지 한국에 Smart Grid를 구축할 계획을 가지고 추진하고 있다. Smart Grid는 지능형 전력망으로 기존의 전력망에 IT를 접목시켜 통신을 실시하여 양방향성을 가지게 된다. 기존의 전력망에 부가될 IT전기기기들은 기존에 IT가 지니고 있는 취약점들이 있어 기존의 Smart Grid공격에 노출되어 있다. 본 논문에서는 한국보다 먼저 구축되어서 활용되고 있는 미국의 Smart Grid에 대한 공격사례를 분석한다. 그리고 한국 Smart Grid에 대한 전기IT기기의 취약점을 분석하여, 한국 Smart Grid에 대한 예상 공격을 분석하고, 보안 대책을 제시한다. 본 논문은 한국 Smart Grid에 안정성과 보안성을 갖춘 기술 자료로 활용할 것이다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.273-274
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• 2007

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.4
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• pp.613-620
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• 2017

The power grid has been changed to a smart grid system to satisfy the growing need for power grid complexity, demand, reliability, security, and efficiency with a combination of existing power and ICT technology. This study analyzes the research trends in smart grid technology in the period since the introduction of the smart grid system and compares it with industrial trends to grasp the progress and characteristics of Smart Grid technology and look for ways to innovate the technology. To do this, we analyze the research trends using dynamic topic modeling, which is capable of time-series research topic analysis. Next, we compare the results of research trends with industrial trends analyzed by Gartner's experts to demonstrate that smart grid research is evolving to the level of industrialization. The results of this study are quantitative analysis through data mining, and it is expected that it will be used in many fields such as companies that want to participate in industry and government agencies that need to establish policies by showing more objective analysis results.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1245-1254
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• 2018

The stability of a grid-connected system (GCS) has become a critical issue with the increasing utilization of renewable energy sources. Under grid faults, however, a grid-connected inverter cannot work efficiently by using only the traditional droop control. In addition, the unbalance factor of voltage/current at the common coupling point (PCC) may increase significantly. To ensure the stable operation of a GCS under grid faults, the capability to compensate for grid imbalance should be integrated. To solve the aforementioned problem, an improved voltage-type grid-connected control strategy is proposed in this study. A negative sequence conductance compensation loop based on a positive sequence power droop control is added to maintain PCC voltage balance and reduce grid current imbalance, thereby meeting PCC power quality requirements. Moreover, a stable analysis is presented based on the small signal model. Simulation and experimental results verify the aforementioned expectations, and consequently, the effectiveness of the proposed control scheme.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.1021-1023
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• 2005

데이터 그리드는 방대한 양의 데이터를 효율적이면서도 편리하게 관리하는 것이 목적이다. 최근에는 멀티미디어와 정보화 기기의 발달로 개인 데이터의 양이 점차 많아 지고 있는 추세이며, 휴대전화와 PDA, PC등 다양한 환경에서 개인 데이터에 대한 접근을 필요로 하고 있다. 본 연구에서는 다양한 클라이언트 환경을 지원하기 위한 그리드 파일 시스템을 개발하고 구현하였다. 본 연구에서 개발된 시스템에서는 관계형 데이터베이스를 이용하여 웹 및 전용 클라이언트를 비롯한 다양한 클라이언트를 지원할 수 있으며, URL과 칼은 고유의 파일 위치 정보를 이용하여 파일의 접근 방식을 표현한다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.16-18
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• 2005

계산 그리드는 대형 컴퓨팅 자원을 필요로 하는 기관들이 계산 자원이나 저장 공간등을 공유함으로써 자원의 이용 효율을 높이고 사용자들에게 보다 다양한 컴퓨팅 서비스를 지원하는 것이 목적이다. 그러나, 컴퓨팅 자원을 많은 수의 사용자 커뮤니티내에서 공유하기 위해서는 자원의 사용과 관련된 어카운팅 정보를 사용자별로 정확하게 수집함으로써 자원의 사용 정책 등에 반영하여야 한다. 그러나, 기존의 어카운팅 방법으로는 그리드상의 수많은 자원들을 효율적으로 관리하기 어렵다. 본 연구에서는 그리드 환경에서 사용자 어카운팅을 구현할 수 있도록 계산 그리드의 클러스터를 기반으로 한 사용자 환경을 설계하였다. 본 연구에서 설계된 시스템은 사용자들이 동일한 자원을 이용할 때 서로 충돌되지 않고, 각자 독립된 접근 영역 안에서 자원을 이용할 수 있게 함으로써 사용자 어카운팅을 간편하게 만들어 준다는 특징이 있다.