• Title, Summary, Keyword: Performance index

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Asymmetric Index Management Scheme for High-capacity Compressed Databases (대용량 압축 데이터베이스를 위한 비대칭 색인 관리 기법)

  • Byun, Si-Woo;Jang, Seok-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.293-300
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    • 2016
  • Traditional databases exploit a record-based model, where the attributes of a record are placed contiguously in a slow hard disk to achieve high performance. On the other hand, for read-intensive data analysis systems, the column-based compressed database has become a proper model because of its superior read performance. Currently, flash memory SSD is largely recognized as the preferred storage media for high-speed analysis systems. This paper introduces a compressed column-storage model and proposes a new index and its data management scheme for a high-capacity data warehouse system. The proposed index management scheme is based on the asymmetric index duplication and achieves superior search performance using the master index and compact index, particularly for large read-mostly databases. In addition, the data management scheme contributes to the read performance and high reliability by compressing the related columns and replicating them in two mirrored SSD. Based on the results of the performance evaluation under the high workload conditions, the data management scheme outperforms the traditional scheme in terms of the search throughput and response time.

Search scheme for parallel spatial index (병렬 공간 색인을 위한 검색 기법)

  • Seo, Young-Duk
    • Journal of Korea Spatial Information System Society
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    • v.7 no.2
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    • pp.81-89
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    • 2005
  • Declustering and parallel index structures are important research areas to improve a performance of databases. Previous researches proposed several distribution schemes for parallel R-trees, however there is no search schemes to be suitable for the index. In this paper, we propose schemes to improve the performance of range queries for distribute parallel indexes. The proposed schemes use the features that a parallel disk can read multiple nodes from various disks. The proposed schemes are verified using various implementations and performance evaluations. We propose new schemes which can read multiple nodes from multiple disks in contrast that to the previous schemes which can read a node from disk. The experimental evaluation shows that the proposed schemes give us the performance improvement by 40% from the previous researches.

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Sweet Area Determination by Performance Sensitivity Analysis for an Automotive Vehicle Suspension (자동차용 현가장치의 성능감도해석에 의한 안정승차영역의 결정)

  • Park, Ho;Hahn, Chang-Su;Kim, Byeong-Woo;Kim, Dong-Gyu
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.1
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    • pp.92-100
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    • 2003
  • Using a quarter car model, an analytic method for performance estimation of a vehicle suspension system with respect to frequency response, RMS response and performance index is presented. From frequency response function, compromization of response performance to the whole frequency range is verified and from RMS response and performance index, sensitivity of ride md handling characteristics are examined. Using a full car model, sweet area(stable ride area) are determined and performance sensitivity is estimated according to the change of feedback gains. In order to esimate the output sensitivity, response we is displayed using a 3-dimensional contour plot. Design data n suggested for optimal design parameter esimation, which maximize the performance of the given suspension system.

Research on Laminate Design Parameters to Maximize Performance Index of Composite Pressure Vessel (복합재 압력용기의 성능지수 최대화를 위한 적층 설계변수 연구)

  • Jeong, Seungmin;Hwang, Taekyung
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.3
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    • pp.21-27
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    • 2018
  • In this paper the laminate design parameters are researched to maximize the performance index of a composite pressure vessel. To maximize the performance index, the three design variables that the thickness of each of helical and hoop layers and the length of hoop layer are considered under the assumption of fixed internal space. To optimize the variables, the response surface method is introduced for construction of the surrogate model and the ANOVA(analysis of variance) is performed to evaluate the effects of the variables. The optimization problem is formulated to maximize performance index under the burst pressure constraint. To verify the effectiveness of the research, numerical analyses are performed for the optimum model.

An Analysis on the Effect of the PID Controller Design Due to Performance Index (평가지표에 따른 PID 제어기 설계 영향 분석)

  • Lee, Keum-Won
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.1
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    • pp.52-58
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    • 2005
  • Among various modern control theories, PID control has been well used for several decades. PID algorithms need some tuning methods which are used for selecting PID parameters. But in some cases various kinds of performance indices are used instead of well-known tuning rules, and so variable type of performance index must be tested so that controllers, output characteristics and disturbance rejection property meet some specifications. In this paper, linear conbinational type of performance index using error signal, time, control input and robustness is used to the PID control of air conditioning system. By use of the 2 DOF PID parmeters minimizing perfromacne index controllers, output characteristics and robustness properties are analyzed. Simulations are done by use of MATLAB with Simulink.

Research on Laminate Design Parameters to Maximize Performance Index of Composite Pressure Vessel (복합재 압력용기의 성능지수 최대화를 위한 적층 설계변수 연구)

  • Jeong, Seungmin;Hwang, Taekyung
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.529-535
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    • 2017
  • In this paper the laminate design parameters are researched to maximize the performance index of a composite pressure vessel. The pressure-resistant performance and the light-weight concept with contained internal space are implied in the performance index. To maximize the performance index, the three design variables that the thickness of each of helical and hoop layers and the length of hoop layer are considered under the assumption of fixed internal space. To optimize the variables, the response surface method is introduced for construction of the surrogate model and the ANOVA(analysis of variance) is performed to evaluate the effects of the variables. The optimization problem is formulated to maximize performance index under the burst pressure constraint. To verify the effectiveness of the research, numerical analyses are performed for the optimum model.

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A Development of the Performance Measurement System for Safely Management (안전관리 성과측정 시스템 개발)

  • 이영순;김용수;박교식;김형석
    • Journal of the Korean Society of Safety
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    • v.15 no.4
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    • pp.157-162
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    • 2000
  • A performance measurement system for safety management was suggested with which performance of a company's safety activities can be expressed rationally, and analysis of impact with performance improvement. A key of the measurement system is performance index of the safety management activities, which consists of 3 perspectives; an external perspective, an internal perspective, and a innovation & learning perspective. Every perspective consists of 18 performance indices and each indices consist of activity unit a such planning, support, implementation, evaluation and review.

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Optimal Discrete Systems using Time-Weighted Performance Index with Prescribed Closed-Loop Eigenvalues

  • Gwon, Bong-Hwan;Yun, Myeong-Jung
    • Proceedings of the KIEE Conference
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    • pp.786-790
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    • 1987
  • An optimization problem minimizing n given time-weighted performance index for discrete-time linear multi-input systems is investigated for the prespecified closed-loop eigenvalues. Necessary conditions for an optimality of the controller that satisfies the specified closed-loop eigenvalues are derived. A computational algorithm solving the optimal constant feedback gain is presented and a numerical example is given to show the effect of a time-weighted performance index on the transient responses.

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Optimal Constant PIDM Feedback Controller using Time Weighted Performance Index for Linear Multivariable Systems (선형 다변수 시스템에 있어서 시간비중 성능지수를 이용한 최적 상수 PIDM 궤한 제어기)

  • 권봉환;윤명중
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.5
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    • pp.360-366
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    • 1987
  • The design problem of optimal constant PIDM (proportional-integral-derivative and measurable variable) feedback controller for linear time-invariannt systems is investigated with the time-weighted quadratic performance index. Necessary conditions for an optimality of the controller are derived and an algorithm for computing the optimal feedback gain is presented. It is shown via example that the design mithod using the time-weighted quadratic performance index improves the transient responses of the closed-loop system.

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Calculation of Seismic Capacity Evaluation Index of Shear Wall System (전단벽 구조시스템의 내진성능평가 지표 산정)

  • Park, Tae-Won;Na, Seong-Uk;Woo, Woon-Taek;Chung, Lan
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.223-230
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    • 2002
  • Earthquake resistance design has been developed many countries like Japan, USA, Mexico, New Zealand etc., which countries have experienced many earthquakes. Nowadays, earthquake resistance design has come into worldwide use. In Korea, the seismic design regulations have been established since 1988 in order to minimize the economic losses. Recently performance based design method has been adopted as a new Earthquake resistance design method. These regulations, however, are targeted for newly constructed buildings, In Korea, there are no regulations for existing buildings that built before 1988. On the other hand, in Japan and USA, the seismic performance evaluation is coded. In Japan, the evaluation index which can measure seismic performance has been made. So, we need to prepare the regulations that evaluate the seismic performance, furthermore proper retrofitting design guideline needs to be proposed when remodeling old buildings. In this research, various seismic performance evaluation methods which are being used in Japan and USA are reviewed in order to establish seismic performance evaluation index for those existing old structures in Korea.

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