• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.125-136
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• 2011

The vulnerabilities existed in Korean electricity control systems is unexposed because it is being operated in a closed network with superior security. The threat will become greater once the closed network develops into a smart grid environment with superior intelligence. Security will have a greater impact once each household will be connected to the power plant via the smart meter. This research focuses on stable data transfer in harsh external environment and whole-nation coverage network, and suggested standardized and optimized Virtual Private Network (VPN) Gateway architecture to support Power Line Communication (PLC). The functionality and stability of the prototype has been verified with field tests. For implementation of outdoor type VPN device for smart grid, we adopted PLC low voltage remote-meter-net for data communication. Also, IPSec type tunneling and ARIA algorithm based encryption of data collected by PLC low voltage remote meter is transmitted.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.725-733
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• 2023

The purpose of this study is to evaluate the effectiveness of virtual grid software (VGS). The purpose of this study is to evaluate the changes in energy and object thickness by dividing the use of VGS into two cases (Without-VGS) without using a movable grid. We attempted to determine the effectiveness of VGS by acquiring images using a chest phantom and a thigh phantom and analyzing SNR and CNR. In the chest phantom and femoral phantom, the tube flow was fixed at 2.5 mAs, and the tube voltage was changed by 10 kVp from 60 to 100 kVp to measure SNR and CNR, and SNR was about 1.09 to 8.86% higher in the chest phantom than in Without-VGS, and CNR was 4.18 to 14.56% higher in the VGS than in Without-VGS. And in the femoral phantom, SNR was about 9.78 to 18.05% higher in VGS than in Without-VGS, and CNR was 21.07 to 44.44% higher in VGS than in Without-VGS. The tube voltage was fixed at 70 kVp in the chest phantom and the femoral phantom, and the amount of tube current was changed at 2.5 to 16 mAs, respectively, and after X-ray irradiation, SNR and CNR were measured in the chest phantom, which was about 1.49 to 11.11% higher in VGS than in Without-VGS, and CNR was 4.76 to 13.40% higher in VGS than in Without-VGS. And in the femoral phantom, SNR was about 2.22 to 17.38% higher in VGS than in Without-VGS, and CNR was 13.85 to 40.46% higher in VGS than in Without-VGS. Therefore, if an inspection is required with a mobile X-ray imaging device, it is believed that good image quality can be obtained by using VGS in an environment where it is difficult to use a mobile grid, and it is believed that the use of mobile X-ray devices can be increased.

• The Journal of the Korea Contents Association
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• v.9 no.1
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• pp.98-105
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• 2009

In this paper, new data centric storage that is dynamically adapted to the change of work load is proposed. The proposed data centric storage distributes the load of hot spot area by using multilevel grid technique. Also, the proposed method is able to use existing routing protocol such as GPSR (Greedy Perimeter Stateless Routing) with small changes. Through simulation the proposed method enhances the lifetime of sensor networks over one of the state-of-the-art data centric storages. We implement the proposed method based on a operating system for sensor networks, and evaluate the performance through running based on a simulation tool.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.990-993
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• 2019

인공지능(AI)은 최근 다양한 산업과 사회에서 패러다임을 바꾸고 있지만, 최첨단 AI 가 제조업에서는 즉각적인 성과를 보이지 못 하고 있다. 다시 말해, Industry 4.0 시점에서 기존의 접근 방법과 차별화되는 실용적인 방법론이 필요하다. 여기서 중요한 점은 '어떤' 데이터를 '어떻게' 활용하여 '어느' 부분에 적용할 것 인가이다. 제조업은 게임과 같이 가상의 캐릭터가 하나의 객체 단위로 구동되는 것이 아니라 수많은 하드웨어가 물리적으로 조합되어 연동한다. 따라서, 현실 세계에서는 물리적 마모, 고장 등으로 인해 엔지니어의 개입 없이 수천만 번 이상의 반복 학습이 불가능하다. 또, 제조업은 학습을 위한 방대한 양의 데이터를 수집하고 레이블링 하는 것이 매우 어렵다. 이 두 가지 한계를 극복할 수 있는 방법은 현실과 매우 유사한 환경을 시뮬레이션으로 재연 후 강화 학습을 사용하는 것이다. 제조 분야에서 아주 복잡한 환경 중 하나로 이송 설비가 있으며, 본 논문에서는 그리드 분류 시스템을 개발하고 강화 학습을 적용시킬 수 있는 환경을 설계한다.

• Journal of the Korean GEO-environmental Society
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• v.2 no.4
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• pp.39-50
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• 2001

In this study, in order to investigate the effects of reinforcement length and vertical spacing on the factor of safety, the road embankment reinforced by geogrid was analyzed using RSS(Reinforced Slope Stability) program based on limit equilibrium analysis. The result by computer analysis showed that the factor of safety for reinforced slope increased with increasing length of reinforcement and with decreasing vertical spacing of reinforcement up to certain limit. Also, numerical analysis by FLAC was performed on reinforced slope to evaluate the horizontal displacement, horizontal stress, and distribution of tensile forces of reinforcements in the cases of several reinforcement length. The results of analysis showed that the critical failure mode was toe failure or slope failure and the effect by the additional reinforcement length on the slope stability was negligible under stabilized condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4B
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• pp.227-235
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• 2012

Holes that generated by the unpredictable and harsh nature application environment or uneven energy consumption are an inevitable phenomenon in wireless sensor networks. Most of the existing schemes for this hole problem tend to use a static detour path to bypass a hole. The static detour path may lead to uneven energy consumption of the nodes on the boundary of the hole, thus it may enlarge the region of holes. At the same time, traffic would concentrate on the nodes on the boundary of the hole and tend to be depleted quickly. To solve this problem, we introduce energy-efficient grid-based geographic routing and hole-detouring scheme by taking advantage of grid anchor point in wireless sensor network with holes. The location of hole detour anchor node is dynamically shifted in grid cell. just generating dynamic hole detour paths to reduce total energy consumption. Simulation results are provided to validate the claims.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.2
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• pp.189-198
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• 2004

As display devices evolve, computer-based work environments are also becoming better suited to actual application tasks. This paper discusses the development of an architectural design system using the virtual table, which is a table-type projection system. It consists of the interactive VR modeler, the hybrid tracker and the architectural interpreter. The interactive VR modeler offers visual and tactile guide such as grid interaction, a tangible transparent prop and reference objects, so that a user can design architectural 3D models more easily and intuitively on the virtual table. The hybrid tracker includes two types of tracking methods for viewpoint according to the user's view and hand interaction: namely, vision-based tracking and magnetic tracking. The architectural interpreter automatically transforms simple 3D masses into a basic construction form that has architectural knowledge. The proposed system has advantage in the sense that it is suitable for collaboration among several users, allowing them to view graphical objects in stereoscopic view with direct 3D manipulation. Thus, it can be effectively used for architectural simulation and user-participated design.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.11
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• pp.269-274
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• 2018

MMORPG is a role-playing game that tens of thousands of people access it online at the same time. Users connect to the server through the game client and play with their own characters. If the user moves to a management area of another server beyond the area managed by the server, the user information must be transmitted to the server to be moved. In an actual game, the user is required to synchronize the established and the transferred information. In this paper, we propose a migration agent server in the virtual systems. We implement a seamless virtual server using the grid method to experiment with seamless server architecture for virtual systems. We propose a method to minimize the delay and equalize the load when the user moves to another server region in the virtual environment. Migration Agent acts as a cache server to reduce response time, the response time was reduced by 50% in the case of 70,000 people.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.8
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• pp.825-836
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• 2010

The advancement of electronic records brought great changes of the records management system. One of the biggest changes is the transition from passive to automatic management system, which manages massive records more efficiently. The integrated Rule-Oriented Data System (iRODS) is a rule-oriented grid system S/W which provides an infrastructure for building massive archive through virtualization. It also allows to define rules for data distribution and back-up. Therefore, iRODS is an ideal tool to build an electronic record management system that manages electronic records automatically. In this paper we describe the issues related to design and implementation of the electronic record management system using iRODS. We also propose a system that serves automatic processing of distribution and back-up of records according to their types by defining iRODS rules. It also provides functions to store and retrieve metadata using iRODS Catalog (iCAT) Database.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.299-308
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• 2022

Recent, energy transition policies are driving to increase in the number of small photovoltaic(PV) generators. It is difficult for system operators to accurately anticipate the amount of power generated from such small scale PV generation, and this may disrupt dispatch schedules and result in an increase in cost. The need for a Virtual Power Plant(VPP) is emerging as a way of resolving these problems, as it would integrate small-scale PV plants and eliminate uncertainty about the amount of power generated, control voltage, and provide power reserves. In this paper, the cost evaluation methods are described for determination of VPP cloud charges both Net Present Value(NPV) method and Profitability Index(PI) method, the calculated outcomes of the two types of cost evaluation methods are presented in detail. It seems we secure profitability as we get 1.22 of profitability index from calculation results, it may be attractive for the aggregator as NPV is enough for satisfying profitability.