• Title, Summary, Keyword: performance index

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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 Quantitative Performance Index for an Input Observer (II) - Analysis in Steady-State - (입력관측기의 정량적 성능지표 (II) -정상상태 해석-)

  • Jung, Jong-Chul;Lee, Boem-Suk;Huh, Kun-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.10
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    • pp.2067-2072
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    • 2002
  • The closed-loop state and input observer is a pole-placement type observer and estimates unknown state and input variables simultaneously. Pole-placement type observers may have poor performances with respect to modeling error and sensing bias error. The effects of these ill-conditioning factors must be minimized for the robust performance in designing observers. In this paper, the steady-state performance of the closed-loop state and input observer is investigated quantitatively and is represented as the estimation error bounds. The performance indices are selected from these error bounds and are related to the robustness with respect to modeling errors and sensing bias. By considering both transient and steady-state performance, the main performance index is determined as the condition number of the eigenvector matrix based on $L_2$-norm.

Performance Study of the Index-based Parallel Join

  • Jeong, Byeong-Soo;Edward Omiecinski
    • The Journal of Information Technology and Database
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    • v.2 no.2
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    • pp.87-109
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    • 1995
  • The index file has been used a access database records effectively. The join operation in a relational database system requires a large execution time, especially in the case of handling large size tables. If the indexes are available on the joining attributes for both relations involved in the join and the join selectivity is relatively small, we can improve the execution time of the join operation. In this paper. we investigate the performance trade-offs of parallel index-based join algorithms where different indexing schemes are used. We also present a comparison of our index-based parallel join algorithms with the hash-based parallel join algorithm.

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A Column-Aware Index Management Using Flash Memory for Read-Intensive Databases

  • Byun, Si-Woo;Jang, Seok-Woo
    • Journal of Information Processing Systems
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    • v.11 no.3
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    • pp.389-405
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    • 2015
  • Most traditional database systems exploit a record-oriented model where the attributes of a record are placed contiguously in a hard disk to achieve high performance writes. However, for read-mostly data warehouse systems, the column-oriented database has become a proper model because of its superior read performance. Today, flash memory is largely recognized as the preferred storage media for high-speed database systems. In this paper, we introduce a column-oriented database model based on flash memory and then propose a new column-aware flash indexing scheme for the high-speed column-oriented data warehouse systems. Our index management scheme, which uses an enhanced $B^+$-Tree, achieves superior search performance by indexing an embedded segment and packing an unused space in internal and leaf nodes. Based on the performance results of two test databases, we concluded that the column-aware flash index management outperforms the traditional scheme in the respect of the mixed operation throughput and its response time.

Low Sensitive Optimal Steering System of Ships at Sea (저감도최적조타계의 설계에 관한 연구)

  • 이철영
    • Journal of the Korean Institute of Navigation
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    • v.4 no.1
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    • pp.19-30
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    • 1980
  • The usual procedure for the optimal design of ship's steering system is to minimize a chosen quadratic performance index, which isdetermined from the view point of economic run. However, the optimal control synthesized in such a straightforward fashion is unsatisfactory because ship's parameters differ from their nominal values due to uncertainties and errors in measurement and/or simplifications in mathematical modelling, and/or the variation of the ship's loading condition. In an attempt to resolve this difficulty, this paper presents a method for designing a low sensitive optimal steering system in a way as to minimize not only given performance index but also the sensitivity of the performance index and trajectory sensitivity. It is also shown that the optimal control so obtained will result in a system whose performance index and transient response are low sensitive to small varation in ship's time constant.

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Optimization of trusses under uncertainties with harmony search

  • Togan, Vedat;Daloglu, Ayse T.;Karadeniz, Halil
    • Structural Engineering and Mechanics
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    • v.37 no.5
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    • pp.543-560
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    • 2011
  • In structural engineering there are randomness inherently exist on determination of the loads, strength, geometry, and so on, and the manufacturing of the structural members, workmanship etc. Thus, objective and constraint functions of the optimization problem are functions that depend on those randomly natured components. The constraints being the function of the random variables are evaluated by using reliability index or performance measure approaches in the optimization process. In this study, the minimum weight of a space truss is obtained under the uncertainties on the load, material and cross-section areas with harmony search using reliability index and performance measure approaches. Consequently, optimization algorithm produces the same result when both the approaches converge. Performance measure approach, however, is more efficient compare to reliability index approach in terms of the convergence rate and iterations needed.

Fuel Economy Optimization of Hybrid Vehicle Using Single Performance Index (단일 성능지수를 이용한 하이브리드 차량의 연비 성능 최적화)

  • Cho, Sung-Tae;Jun, Soon-Il;Kong, Jin-Hyung;Park, Yeong-Il;Lee, Jang-Moo
    • Proceedings of the KSME Conference
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    • pp.552-557
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    • 2001
  • To minimize the fuel consumption in the hybrid vehicle, the single performance index, which can express the fuel consumption in engine and electric energe consumption in battery system at the same time, is required. In this study we proposed a single performance index with equivalent BSFC concept, and with this, we constructed driving control algorithm, which can determine optimal gear ratio and power split ratio of the engine and the motor, for the parallel hybrid vehicle. Additionally, to verify the validity of this algorithm, driving simulation is performed.

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Comparative Analysis on Performance Indices of Obstacle Detection for an Overlapped Ultrasonic Sensor Ring (중첩 초음파 센서 링의 장애물 탐지 성능 지표 비교 분석)

  • Kim, Sung-Bok;Kim, Hyun-Bin
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.4
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    • pp.321-327
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    • 2012
  • This paper presents a comparative analysis on three different types of performance indices of obstacle detection for an overlapped ultrasonic sensor ring. Due to beam overlap, the entire sensing zone of each ultrasonic sensor can be divided into three smaller sensing subzones, which leads to significant reduction of positional uncertainty in obstacle detection. First, the positional uncertainty in obstacle detection is expressed in terms of the area of a sensing subzone, and type 1 performance index is then defined as the area ratio of side and center sensing subzones. Second, based on the area of a sensing subzone, type 2 performance index is defined taking into account the size of the entire range of obstacle detection as well as the degree of the positional uncertainty in obstacle detection. Third, the positional uncertainty in obstacle detection is now expressed in terms of the length of the uncertainty arc spanning a sensing subzone, and type 3 performance index is then defined as the average value of the uncertainty arc lengths over the entire range of obstacle detection. Fourth, using a commercial low directivity ultrasonic sensor, the changes of three different performance indices depending on the parameter of an overlapped ultrasonic sensor ring are examined and compared.

A Study on the Performance of Similarity Indices and its Relationship with Link Prediction: a Two-State Random Network Case

  • Ahn, Min-Woo;Jung, Woo-Sung
    • Journal of the Korean Physical Society
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    • v.73 no.10
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    • pp.1589-1595
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    • 2018
  • Similarity index measures the topological proximity of node pairs in a complex network. Numerous similarity indices have been defined and investigated, but the dependency of structure on the performance of similarity indices has not been sufficiently investigated. In this study, we investigated the relationship between the performance of similarity indices and structural properties of a network by employing a two-state random network. A node in a two-state network has binary types that are initially given, and a connection probability is determined from the state of the node pair. The performances of similarity indices are affected by the number of links and the ratio of intra-connections to inter-connections. Similarity indices have different characteristics depending on their type. Local indices perform well in small-size networks and do not depend on whether the structure is intra-dominant or inter-dominant. In contrast, global indices perform better in large-size networks, and some such indices do not perform well in an inter-dominant structure. We also found that link prediction performance and the performance of similarity are correlated in both model networks and empirical networks. This relationship implies that link prediction performance can be used as an approximation for the performance of the similarity index when information about node type is unavailable. This relationship may help to find the appropriate index for given networks.

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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