• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2064-2067
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• 2000

In our country, most region is composed of mountains and people have recently been displeased with the construction of the substations in their vicinity so the substations newly built are mainly constructed with GIS system in the small area that has high soil resistivity near mountain. Therefore, nowadays the design of substation grounding system has been difficult, and the additional considerations are needed. UC substation was also difficult to design the grounding system because of so small substation area and high soil resistivity. This paper shows the examples of reducing the grounding system resistance reasonably by using several ways. Designing the ground grid electrode in the access road, deep electric earth probe, changing the substation soil with the law level resistivity soil. This report deals with the computer simulation of the grounding system resistance about the ways illustrated above.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.94-96
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• 2003

차세대 통신에서는 컴퓨터자원들이 지속적으로 대용량화 고속화되는 추세이며 특히 생명공학, 유전공학, 유체역학 기상기후 예측 동 여러 과학 분야에서 단일자원으로는 제공하기 힘든 계산 및 저장자원을 요구 하고 있다. 이러한 문제를 해결하기 위해서 지리적으로 분산 되어있는 자원들을 연결하여 마치 단일 차원을 사용하는 것처럼 해주는 서비스인 그리드가 대두 되었다. 그러나 그리드 사용자가 작업을 수행시키기 위해서는 자신의 DN(Distinguished Mame)을 Remote Machine상에 Local User Account를 바인딩 시켜줘야 한다. 따라서 각 사이트 관리자는 그리드 서비스를 제공하기 위해 수많은 그리드 사용자의 DN과 Local User Account를 바인딩 처리를 해 주어야 한다. 그러나 사실상 현실적으로 불가능하다. 이러한 문제를 해결하기 위해서 본 논문에서는 그리드 사용자에 대한 정책기반 접근 제어 시스템을 설계 및 구현했다.

• Journal of KIISE:Databases
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• v.31 no.6
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• pp.596-608
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• 2004

A lot of work has been done to reduce disk access time in I/O intensive systems, which store and handle massive amount of data, by distributing data across multiple disks and accessing them in parallel. Most of the previous work has focused on an efficient mapping from a grid cell to a disk number on the assumption that data space is regular grid-like partitioned. Although we can achieve good performance for low-dimensional data by grid-like partitioning, its performance becomes degenerate as grows the dimension of data even with a good disk allocation scheme. This comes from the fact that they partition entire data space equally regardless of distribution ratio of data objects. Most of the data in high-dimensional space exist around the surface of space. For that reason, we propose a new declustering algorithm based on the partitioning scheme which partition data space from the surface. With an unbalanced partitioning scheme, several experimental results show that we can remarkably reduce the number of data blocks touched by a query as grows the dimension of data and a query size. In this paper, we propose disk allocation schemes based on the layout of the resultant data blocks after partitioning. To show the performance of the proposed algorithm, we have performed several experiments with different dimensional data and for a wide range of number of disks. Our proposed disk allocation method gives a performance within 10 additive disk accesses compared with strictly optimal allocation scheme. We compared our algorithm with Kronecker sequence based declustering algorithm, which is reported to be the best among the grid partition and mapping function based declustering algorithms. We can improve declustering performance up to 14 times as grows dimension of data.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.61-63
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• 2003

인터넷 기반의 컴퓨팅 환경이 발전함에 따라 자원과 정보의 공유를 위한 그리드 컴퓨팅이 나타나게 되었다. 그리드 컴퓨팅에서는 그리드 응용 수행시 프로그램과 데이터간의 위치가 다르고 분산되어 있는 경우가 많다. 현재 그리드 미들웨어 시장 표준인 글로버스 둘킷(Globus Toolkit$_{TM}$)에서 사용하는 GASS(Global Access to Secondary Storage)는 원격에 있는 관련 데이터들을 로컬 시스템의 데이터에 접근하는 것처럼 처리하는 것을 지원한다. GASS에서는 원격지의 파일 시스템의 접근시 URL(Uniform Resource Locator)을 이용하는데, 그리드 환경에서의 I/O을 위한 파일 시스템은 복수의 파일 형태로 분산되어있기 때문에 하나의 그리드 응용을 수행할 때 URL을 동적으로 바꿔야 하는 문제점을 갖고 있다. 위치에 상관 없고 고성능을 지향하고 데이터의 성격을 쉽게 표현할 수 있는 이름 체제가 필요하다. 그래서 본 연구는 동적이고 다양한 표현이 가능한 URI(Uniform Resource Identifiers)을 사용하여 그리드 상에서 데이터를 사용하는 방법을 제안하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.46-48
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• 2003

미국 페르미연구소에서 현재 수행되고 있는 고에너지물리 실험의 하나인 CDF 실험에서는 현재 303대의 Dual CUP 클러스터를 이용한 중심분석용팜(CAF, Central Analysis Farm)을 페르미 연구소 내에 구성하여 실제 데이터 처리 및 모의 시늉 데이터를 생산하는데 사용하고 있다. 그러나 페르미 연구소에서의 중심분석용팜(CAF)은 향후 그 자원이 충분치가 못하므로, 이에 참여하고 있는 여러 나라의 컴퓨팅 자원들을 공유할 수 있어야 한다. 따라서, 한국그룹은 경북대학교 고에너지물리연구소에 있는 PC 클러스터를 활용하여 탈중심분산팜 (DCAF, DeCenteralized Analysis Farm)을 국제공동연구로 설계하여 테스트베드를 구축하였다. 이 구성에는 CAF의 기술뿐만 아니라 페르미 연구소라는 원격에 있는 실험 데이터를 이용하여 job을 수행하므로 데이터 전송 기술인 SAM(Sequential data Access via Meta-data) 및 Kerberos의 보안 시스템, 그리드(Grid)를 포함하는 모든 IT 기술의 종합으로 이루어져있다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.580-582
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• 2005

거리가 상당히 먼 곳에서 고가의 장비를 사용하기 위해서는 사용할 연구 인력이 직접 와야 하는 많은 시간적 비용적 문제가 발생한다. 특히 본원에 장비되어 있는 초고전압 투과전자현미경(High Voltage Electron Microscopy - 이하 HVEM)의 경우 고가의 장비로 지역마다 기기를 구비할 수 없어 사용자는 직접 장비가 있는 연구실까지 와서 사용해야 한다. HVEM은 1천만 배율의 성능을 가진 국내 유일은 물론 전 세계적으로도 손꼽히는 고성능의 투과전자현미경으로 NT(Nano Technology), BT(Bio Technology) 연구에 있어서 핵심적인 역할을 하는 청단 연구기기이다. 따라서 본 논문에서는 그리드 컴퓨터 기술을 이용하여 HVEM을 원격제어 하는 시스템을 구축하였다.

• Molecules and Cells
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• v.43 no.3
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• pp.298-303
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• 2020

Cryo-electron microscopy (cryo-EM) is now the first choice to determine the high-resolution structures of huge protein complexes. Grids with two-dimensional arrays of holes covered with a carbon film are typically used in cryo-EM. Although semi-automatic plungers are available, notable trial-and-error is still required to obtain a suitable grid specimen. Herein, we introduce a new method to obtain thin ice specimens using real-time measurement of the liquid amounts in cryo-EM grids. The grids for cryo-EM strongly diffracted laser light, and the diffraction intensity of each spot was measurable in real-time. The measured diffraction patterns represented the states of the liquid in the holes due to the curvature of the liquid around them. Using the diffraction patterns, the optimal time point for freezing the grids for cryo-EM was obtained in real-time. This development will help researchers rapidly determine high-resolution protein structures using the limited resource of cryo-EM instrument access.

• Korea Information Processing Society Review
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• v.15 no.2
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• pp.15-28
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• 2008

The Korea UK e-Science Collaboration project has been aimed at supporting research and collaboration between Korean and UK researchers. Its goal is to benefit the nation by reducing cost and time in constructing the National e-Science Research Environment' by studying and benchmarking the cases in countries that have already procured advanced technologies in the area. Two joint workshops were held in a year where researchers from the two countries had the opportunities to share their research results with each other. Also, the project has supported exchanges of researchers fostering expertise in the field. In the course of the project, the e-Science Centre in the UK and KISTI have signed MoU(Memorandum of Understanding) in 2006. Moreover, there have been active research collaboration between Korea and the UK. The University of Southampton will share the BioSimGrid data with the Korean counterpart, and the University of York has provided the AURA software. In the future, KISTI and the UK NGS(National Grid Service) will organize a working group at OGF that will work mainly on the standardization of Parameter Sweep and bring it to lead the global standard. KISTI will include its own AURORA system into OMI-UK software stack, which will enable access to NGS resources through AURORA user application. The collaboration with the UK has opened up more opportunities for collaboration with other countries as well. KISTI and HLRS in Germany have agreed to share the COVISE and will have research exchanges. As such, it is expected that Korea will play a major role in e-Science research by building strategic and systematic collaborative relations with its International partners.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.10
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• pp.1862-1878
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• 2011

With the advances in wireless communication technology and the advent of smartphones, research on location-based services (LBSs) is being actively carried out. In particular, several spatial index methods have been proposed to provide efficient LBSs. However, finding an optimal indexing method that balances query performance and index size remains a challenge in the case of wireless environments that have limited channel bandwidths and device resources (computational power, memory, and battery power). Thus, mechanisms that make existing spatial indexing techniques more efficient and highly applicable in resource-limited environments should be studied. Bitmap-based Spatial Indexing (BSI) has been designed to support LBSs, especially in wireless broadcast environments. However, the access latency in BSI is extremely large because of the large size of the bitmap, and this may lead to increases in the search time. In this paper, we introduce a Selective Bitmap-based Spatial Indexing (SBSI) technique. Then, we propose an Adaptive Bitmap-based Spatial Indexing (ABSI) to improve the tuning time in the proposed SBSI scheme. The ABSI is applied to the distribution of geographical objects in a grid by using the Hilbert curve (HC). With the information in the ABSI, grid cells that have no objects placed, (i.e., 0-bit information in the spatial bitmap index) are not tuned during a search. This leads to an improvement in the tuning time on the client side. We have carried out a performance evaluation and demonstrated that our SBSI and ABSI techniques outperform the existing bitmap-based DSI (B DSI) technique.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.5
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• pp.1339-1355
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• 2023

Localization is a hot research spot for many areas, especially in the mobile robot field. Due to the weak signal of the global positioning system (GPS), the alternative schemes in an indoor environment include wireless signal transmitting and receiving solutions, laser rangefinder to build a map followed by a re-localization stage and visual positioning methods, etc. Among all wireless signal positioning techniques, Wi-Fi is the most common one. Wi-Fi access points are installed in most indoor areas of human activities, and smart devices equipped with Wi-Fi modules can be seen everywhere. However, the localization of a mobile robot using a Wi-Fi scheme usually lacks orientation information. Besides, the distance error is large because of indoor signal interference. Another research direction that mainly refers to laser sensors is to actively detect the environment and achieve positioning. An occupancy grid map is built by using the simultaneous localization and mapping (SLAM) method when the mobile robot enters the indoor environment for the first time. When the robot enters the environment again, it can localize itself according to the known map. Nevertheless, this scheme only works effectively based on the prerequisite that those areas have salient geometrical features. If the areas have similar scanning structures, such as a long corridor or similar rooms, the traditional methods always fail. To address the weakness of the above two methods, this work proposes a coarse-to-fine paradigm and an improved localization algorithm that utilizes Wi-Fi to assist the robot localization in a geometrically similar environment. Firstly, a grid map is built by using laser SLAM. Secondly, a fingerprint database is built in the offline phase. Then, the RSSI values are achieved in the localization stage to get a coarse localization. Finally, an improved particle filter method based on the Wi-Fi signal values is proposed to realize a fine localization. Experimental results show that our approach is effective and robust for both global localization and the kidnapped robot problem. The localization success rate reaches 97.33%, while the traditional method always fails.