• Title/Summary/Keyword: Performance Issues

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Optimized Security Algorithm for IEC 61850 based Power Utility System

  • Yang, Hyo-Sik;Kim, Sang-Sig;Jang, Hyuk-Soo
    • Journal of Electrical Engineering and Technology
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    • v.7 no.3
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    • pp.443-450
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    • 2012
  • As power grids are integrated into one big umbrella (i.e., Smart Grid), communication network plays a key role in reliable and stable operation of power grids. For successful operation of smart grid, interoperability and security issues must be resolved. Security means providing network system integrity, authentication, and confidentiality service. For a cyber-attack to a power grid system, which may jeopardize the national security, vulnerability of communication infrastructure has a serious impact on the power grid network. While security aspects of power grid network have been studied much, security mechanisms are rarely adopted in power gird communication network. For security issues, strict timing requirements are defined in IEC 61850 for mission critical messages (i.e., GOOSE). In this paper, we apply security algorithms (i.e., MD-5, SHA-1, and RSA) and measure their processing time and transmission delay of secured mission critical messages. The results show the algorithms satisfying the timing requirements defined in IEC 61850 and we observer the algorithm that is optimal for secure communication of mission critical messages. Numerical analysis shows that SHA-1 is preferable for secure GOOSE message sending.

Detection Performance and THD Analysis of Active Frequency Drift for Anti-Islanding (단독운전 방지를 위한 능동적 주파수 변환 기법의 검출 성능 및 THD 분석)

  • Jo, Yeong-Min;Choi, Ju-Yeop;Song, Seung-Ho;Choy, Ick;Lee, Young-Kwoun
    • Journal of the Korean Solar Energy Society
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    • v.35 no.2
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    • pp.11-19
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    • 2015
  • Islanding is a phenomenon that EPS(Electric Power System) is continuously energized by PV PCS(Photovoltaic Power Conditioning System) even when EPS is isolated from the grid. Unintentional islanding will result in safety hazard, power quality degradation and many other issues. So, islanding protection of grid-connected PV PCS is a key function for standards compliance. Nowadays, many anti-islanding schemes are researched. But existing anti-islanding schemes used in PV PCS have power quality degradation and non-detection zone issues. This paper analyses not only detection performance of existed anti-islanding schemes using active frequency drift but also THD of PCS output current according to each value disturbance for anti-islanding. In addition, the lowest value of disturbance in each scheme was tabulated under guarantee of anti-islanding condition.

Optimizing Study-life Balance within Higher Education: A Comprehensive Literature Review

  • HATCHER, Ryan;HWANG, Yosung
    • The Journal of Economics, Marketing and Management
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    • v.8 no.2
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    • pp.1-12
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    • 2020
  • Purpose: The rise of the phrase Work Life Balance was bought up in 1986 when amid many Americans there was prevalence of detrimental work place practices like neglecting families, leisure activities and friends in order to achieve their study place goals. The significance of work-life balance has been gaining ground in recent years to grasp a wider range of groups, including students. Searching and finding a balance can be complex and challenging for many individuals and students. Research design, data and methodology: Through this paper we will explore how students balance the competing demands of work, study, and social activities. Several factors have increased imbalances within Educational organizations, and technology specifically has been influential. However, technology also provides a novel solution to this organizational performance management issue. A Study-Life Optimization model (SLO) is suggested, which incorporates information systems, analytics, and decision support into a Smart Service System. A general framework for this model, detailing data collection, measurement, and ethical issues is explained briefly. Results: Outcomes include improved WLB, greater perceived quality of life, and increased Educational organizational performance. Conclusions: This paper contributes to the relevant literature as it pays attention to the various students' of varying lifestyles school-work-personal lives. Findings of this study will provide a meaningful of the Work/school-life balance issues faced by students. The research could be helpful to the various stakeholders of a University, the curriculum designers, program coordinators etc.

LEED PERCEPTION DISPARITIES: DESIGNERS VERSUS NON-DESIGNERS

  • Hyun Woo Lee;Youngchul Kim;Doyoon Kim;Kunhee Choi
    • International conference on construction engineering and project management
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    • 2013.01a
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    • pp.36-41
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    • 2013
  • With the increased interest in green buildings, the building industry has been experiencing a fast-growing demand for LEED (Leadership in Energy and Environmental Design) certification for the last decade. Still, it is not unusual to see various barriers and issues during its implementation, and experience tells that they can result in harming the overall project performance with reworks, lower productivity, schedule delays, and cost overruns. In order to better understand the industry's observation on issues and their consequences during LEED implementation, we distributed an online survey, and a total of 53 responses were received. The survey results indicate that (1) both designers and non-designers (e.g., contractors) select 'added costs to design and construction' as the biggest barrier; (2) both designers and non-designers select 'decision made too late in the design process' as the most frequently observed issue; and (3) non-designers indicate higher perceived severity in every consequence criteria than designers. The statistical analyses reveal that cost overruns are the most severe impact observed and have a statistically significant relationship with responses in regard to the barrier to LEED implementation.

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Big Data Analysis of Software Performance Trend using SPC with Flexible Moving Window and Fuzzy Theory (가변 윈도우 기법을 적용한 통계적 공정 제어와 퍼지추론 기법을 이용한 소프트웨어 성능 변화의 빅 데이터 분석)

  • Lee, Dong-Hun;Park, Jong-Jin
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.11
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    • pp.997-1004
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    • 2012
  • In enterprise software projects, performance issues have become more critical during recent decades. While developing software products, many performance tests are executed in the earlier development phase against the newly added code pieces to detect possible performance regressions. In our previous research, we introduced the framework to enable automated performance anomaly detection and reduce the analysis overhead for identifying the root causes, and showed Statistical Process Control (SPC) can be successfully applied to anomaly detection. In this paper, we explain the special performance trend in which the existing anomaly detection system can hardly detect the noticeable performance change especially when a performance regression is introduced and recovered again a while later. Within the fixed number of sampling period, the fluctuation gets aggravated and the lower and upper control limit get relaxed so that sometimes the existing system hardly detect the noticeable performance change. To resolve the issue, we apply dynamically tuned sampling window size based on the performance trend, and Fuzzy theory to find an appropriate size of the moving window.

Quality Management (QM) Standard Issues in FM - Based on Guidance on quality in European FM Standard

  • Lee, So Young;Jang, Yon Hwa;Lee, Myoung Sik
    • Architectural research
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    • v.18 no.1
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    • pp.21-29
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    • 2016
  • Importance of FM has rapidly increased because of its growing business. However, due to lack of clarity and identity of FM in professional areas, standardization of FM became to be imperative in such a rapidly changing global business environment. Facility services are defined as the provision of support the primary activities of an organization, delivered by an internal or external provider. Majority of FM activities are services related to 'space and infrastructure' and 'people and organization' (CEN, 2011). The purpose of this study is to investigate definitions and characteristics of FM from both globally and domestic environment, by comparison with international or national standards, to identify quality management in FM and service characteristics of FM, to investigate the differences in service level elaboration in FM, and to suggest standard issues of quality management in FM service quality. This study examines contents of the European Standards in FM, Part 3 'Guidance on quality in Facility Management, especially for the process of QM standardized by CEN (2011) and explores undefined issues such as service level, measurement metrics according to service characteristics of FM. The European FM Standard guides the common process of QM in terms of requirements specification, service level elaboration, measurement metrics development although it does not specifically address various service levels, specific performance metrics and indicators.

Investigation of Some Blast Design and Evaluation Parameters for Fragmentation in Limestone Quarries (석회석 광산의 파쇄도 관련 발파설계 및 평가 변수들에 대한 고찰)

  • Rai, Piyush;Yang, Hyung-Sik
    • Tunnel and Underground Space
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    • v.20 no.3
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    • pp.183-193
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    • 2010
  • The present paper highlights some important fragmentation issues experienced in the limestone quarry blast rounds. In light of these major issues, the paper outlines influence of a few important design parameters, which bear merit to alter the blast performance in order to duly resolve the issues in field scale blast rounds. A comprehensive field based program for evaluation of such blast rounds has also been suggested. The knowledge disseminated in the paper, backed up by sufficient images, is largely based on the experience of the authors, while designing, implementing and evaluating numerous field scale blast rounds in cement grade limestone quarries.

A Study on the Security Framework for IoT Services based on Cloud and Fog Computing (클라우드와 포그 컴퓨팅 기반 IoT 서비스를 위한 보안 프레임워크 연구)

  • Shin, Minjeong;Kim, Sungun
    • Journal of Korea Multimedia Society
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    • v.20 no.12
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    • pp.1928-1939
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    • 2017
  • Fog computing is another paradigm of the cloud computing, which extends the ubiquitous services to applications on many connected devices in the IoT (Internet of Things). In general, if we access a lot of IoT devices with existing cloud, we waste a huge amount of bandwidth and work efficiency becomes low. So we apply the paradigm called fog between IoT devices and cloud. The network architecture based on cloud and fog computing discloses the security and privacy issues according to mixed paradigm. There are so many security issues in many aspects. Moreover many IoT devices are connected at fog and they generate much data, therefore light and efficient security mechanism is needed. For example, with inappropriate encryption or authentication algorithm, it causes a huge bandwidth loss. In this paper, we consider issues related with data encryption and authentication mechanism in the network architecture for cloud and fog-based M2M (Machine to Machine) IoT services. This includes trusted encryption and authentication algorithm, and key generation method. The contribution of this paper is to provide efficient security mechanisms for the proposed service architecture. We implemented the envisaged conceptual security check mechanisms and verified their performance.

Routing in Vehicular Ad Hoc Networks: Issues and Protocols

  • Shrestha, Raj K.;Moh, Sang-Man;Chung, Il-Yong
    • Korea Multimedia Society
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    • v.12 no.4
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    • pp.28-40
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    • 2008
  • Vehicular ad hoc networks (VANETs) are a practical application class of wireless ad hoc networks, which consist of moving vehicles equipped with radio communication capabilities that collaborate to form a temporary network. This paper addresses issues and protocols of multihop routing in such emerging networks in the context of safety and infotainment applications. Due to the highly dynamic mobility of vehicles, frequent link breakage and short connection time are inevitable and, thus, the routing is a challenging task and interest for many researchers and industrial community. The frequent and dynamic change of topology makes the topology-based routing unreliable but the position-based routing more effective. The position-based routing consists of the location service which maps a node id to a geo-graphical position and the forwarding scheme which selects the next hop based on geo-graphical information of the node, its neighbors and the destination. The routing techniques are further categorized into geographical forwarding, trajectory forwarding and opportunistic forwarding based on the forwarding scheme. In this paper, we first present the distinguished properties of VANETs and the challenges and intractable issues posed in designing the routing protocols, followed by the comprehensive survey of existing routing protocols. Then, the different routing protocols designed for VANETs are compared in terms of characteristics, performance and application domains.

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A Study on the Improvement of Scoring System by Issues as well as Criteria in the Green Building Certification System for Office Building (업무용 친환경건축물의 득점체계 개선에 관한 연구)

  • Mo, Hye-Ran;Moon, Mi-Seon;Haan, Chan-Hoon;Tae, Choon-Seob
    • Journal of the Korean Solar Energy Society
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    • v.32 no.5
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    • pp.108-117
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    • 2012
  • The purpose of Green Building Certification System is to promote the environment-friendly building construction as the life-cycle environmental performance of a certain building is assessed and certified nationally(domestically). By the way, a building can get the green building certificate just with the minimum standard in prerequisite assessment criteria and with the designated scores in totals. GBCS consists of 9 assessment issues and it has 4 grades. Nevertheless the 1st. grade green building has uneven scores in each issue. In other words, it has even 0 point in a special issue. Due to the above problem, the discrimination and reliability in the GBCS grading and scoring has to be secured. This study aims at a new grading and scoring system equipped with the discrimination and reliability through analysing the scores of prerequisite assessment criteria and the scores by issues in the actually certified green office buildings.