• Title, Summary, Keyword: performance index

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Robust Discrete-Time Observer Design (강인한 이산관측기 설계)

  • 허건수;김상진
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.4
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    • pp.134-140
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    • 1998
  • The authors have shown that the performance of discrete-time observer-based monitoring systems can be represented by the performance index k$_2$(P) (condition number of the eigensystem P of the observer matrix in terms of L$_2$ norm). The observers with the minimized performance index can be defined as robust observers in the sense that the observer performance can be guaranteed in harsh environments. In this paper, based on the performance index, a design methodology for the robust discrete-time observer is developed. Similar to the continuous-time case, the methodology determines the structure and eigenvalues of the observer matrix simultaneously. A complete design procedure is given for single-output case and is illustrated with a spindle-driver example. The simulation results demonstrate the improved performance compared with a traditional pole-placement observer technique.

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Performance Evaluation of SSD-Index Maintenance Schemes in IR Applications

  • Jin, Du-Seok;Jung, Hoe-Kyung
    • Journal of information and communication convergence engineering
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    • v.8 no.4
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    • pp.377-382
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    • 2010
  • With the advent of flash memory based new storage device (SSD), there is considerable interest within the computer industry in using flash memory based storage devices for many different types of application. The dynamic index structure of large text collections has been a primary issue in the Information Retrieval Applications among them. Previous studies have proven the three approaches to be effective: In- Place, merge-based index structure and a combination of both. The above-mentioned strategies have been researched with the traditional storage device (HDD) which has a constraint on how keep the contiguity of dynamic data. However, in case of the new storage device, we don' have any constraint contiguity problems due to its low access latency time. But, although the new storage device has superiority such as low access latency and improved I/O throughput speeds, it is still not well suited for traditional dynamic index structures because of the poor random write throughput in practical systems. Therefore, using the experimental performance evaluation of various index maintenance schemes on the new storage device, we propose an efficient index structure for new storage device that improves significantly the index maintenance speed without degradation of query performance.

A Study on the Laser Measurement Experiment for Performance Advancement of Tilting Index Table (틸팅 인덱스 테이블의 성능 향상을 위한 레이저 측정 실험에 관한 연구)

  • Kim, Kwang-Sun;Lee, Tae-Ho;Lee, Choon-Man
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.5
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    • pp.26-30
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    • 2011
  • Currently, many researches are carried out about tilting index table, which is one of the main component of 5-axis machine tool. The performance of the tilting index table is associated the rotational accuracy which is very important factor for high precision machining because it have an effect on machining error. In this paper, a tilting index table is developed, and the rotational accuracy of the tilting index table using a laser measurement equipment is measured. In addition, a correction value is obtained from the measured value through compensation, and the correction value is used to improve the accuracy of the table. Comparative analysis is carried out for the accuracy of the table before and after compensation. This paper can be used by a reference for performance and reliability advancement of tilting index table.

Evaluation of Smoke Risk and Smoke Risk Rating for Combustible Substances from Fire (화재로부터 연소성 물질에 대한 연기위험성 및 연기위험성 등급 평가)

  • Chung, Yeong-Jin;Jin, Eui;You, Ji Sun
    • Applied Chemistry for Engineering
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    • v.32 no.2
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    • pp.197-204
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    • 2021
  • This study investigated the smoke risk assessment of woods and plastics for construction materials, focusing on the smoke performance index-V (SPI-V), smoke growth index-V (SGI-V), and smoke risk index-VI (SRI-VI) according to a newly designed methodology. Spruce, Lauan, polymethylmethacrylate (PMMA), and polycarbonate (PC) were used for test pieces. Smoke characteristics of the materials were measured using a cone calorimeter (ISO 5660-1) equipment. The smoke performance index-V calculated after the combustion reaction was found to be 1.0 to 3.4 based on PMMA. Smoke risk by smoke performance index-V was increased in the order of PC, Spruce, Lauan and PMMA. Lauan and PMMA showed similar values. The smoke growth index-V was found to be 1.0 to 9.2 based on PMMA. Smoke risk by smoke growth index-V increased in the order of PMMA, PC, Spruce, and Lauan. COpeak production rates of all specimens were measured between 0.0021 to 0.0067 g/s. In conclusion, materials with a low smoke performance index-V and a high smoke growth index-V cause a high smoke risk from fire. Therefore, it is understood that the smoke risk from fire is high. It is collectively summarized by the smoke risk index-VI.

Actrve Suspension Control using aFrequency-Shaped Performance Index (주파수 형태의 성능지수를 고려한 능동형 현가장치 제어)

  • 김희수;기창두;황원걸
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.299-304
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    • 1993
  • A 1/4 car model(2 DOF system) is employed to evaluate the performance included a quadratic cost functional in frequency domain. The design procedure of feedback control to optimize the performance index results in a modified Linear-Quadratic-Gaussian problem and cultivates a quite simple control algorithm. Computer simulation result is shown that the LQG method using frequency shaped performance index is outstanding in ride comfort and its response converges to the steady state very rapidly in comparison with the known passive suspension, classical design methods LQR/ and LQG.

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A Compressed Hot-Cold Clustering to Improve Index Operation Performance of Flash Memory-SSD Systems (플래시메모리-SSD의 인덱스 연산 성능 향상을 위한 압축된 핫-콜드 클러스터링 기법)

  • Byun, Si-Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.1
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    • pp.166-174
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    • 2010
  • SSDs are one of the best media to support portable and desktop computers' storage devices. Their features include non-volatility, low power consumption, and fast access time for read operations, which are sufficient to present flash memories as major database storage components for desktop and server computers. However, we need to improve traditional index management schemes based on B-Tree due to the relatively slow characteristics of flash memory operations, as compared to RAM memory. In order to achieve this goal, we propose a new index management scheme based on a compressed hot-cold clustering called CHC-Tree. CHC-Tree-based index management improves index operation performance by dividing index nodes into hot or cold segments and compressing pointers and keys in the index nodes and clustering the hot or cold segments. The offset compression techniques using unused free area in cold index node lead to reduce the number of slow erase operations in index node insert/delete processes. Simulation results show that our scheme significantly reduces the write and erase operation overheads, improving the index search performance of B-Tree by up to 26 percent, and the index update performance by up to 23 percent.

Empirical Analysis of DEA models Validity for R&D Project Performance Evaluation : Focusing on Rank Correlation with Normalization Index (R&D 프로젝트 성과평가를 위한 DEA모형의 타당성 실증분석 : 정규화지표와의 순위상관을 중심으로)

  • Park, Sung-Min
    • IE interfaces
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    • v.24 no.4
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    • pp.314-322
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    • 2011
  • This study analyzes a relationship between Data Envelopment Analysis(DEA) efficiency scores and a normalization index in order to examine the validity of DEA models. A normalization index concerned in this study is 'sales per R&D project fund' which is regarded as a crucial R&D project performance evaluation index in practice. For this correlation analysis, three distinct DEA models are selected such as DEA basic model, DEA/AR-I revised model(i.e. DEA basic model with Acceptance Region Type I constraints) and Super-Efficiency(SE) model. Especially, SE model is adopted where efficient R&D projects(i.e. Decision Making Units, DMU's) with DEA efficiency score of unity from DEA basic model can be further differentiated in ranks. Considering the non-normality and outliers, two rank correlation coefficients such as Spearman's ${\rho}_s$ and Kendall's ${\tau}_B$ are investigated in addition to Pearson's ${\gamma}$. With an up-to-date empirical massive dataset of n = 482 R&D projects associated with R&D Loan Program of Korea Information Communication Promotion Fund in the year of 2011, statistically significant (+) correlations are verified between the normalization index and every model's DEA efficiency scores with all three correlation coefficients. Especially, the congruence verified in this empirical analysis can be a useful reference for enhancing the practitioner's acceptability onto DEA efficiency scores as a real-world R&D project performance evaluation index.

Optimization of Gradient-index Antireflection Coatings

  • Kim, J. H.;Lee, Y. J.
    • Journal of the Optical Society of Korea
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    • v.4 no.2
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    • pp.86-88
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    • 2000
  • A sequence of functions are examined for the gradient-index AR thin film between two dielectric media and are used as the starting profiles in optimization to improve AR performance. Sinusoidal functions were quite efficient to use as components of the index change in the optimization. It is shown that there exist a number of gradient-index profiles which exhibit excellent AR-performance after control of the gradient-index profiles.

An Exploratory Study on the Causal-effect Relationship between Valuation and Performance in Ventures (벤처기술평가와 경영성과의 인과관계에 관한 탐색연구)

  • Yang, Dong-Woo
    • 한국벤처창업학회:학술대회논문집
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    • pp.61-85
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    • 2006
  • The Purpose of this study is to prove empirically the relationship between ventures' technology valuation and performance, while considering the uniqueness of Korean firms. We use technology valuation index, marketability valuation index, business valuation index as ex-ante independent variables, use firm's performance(sales, asset, operating income ratio, net income ratio etc) as ex-post dependent variables. Parametric analysis such as Paired T-test, ANOVA are applied in this paper. The results of Empirical analysis is summarized as follows. Firstly, operating income ratio and net income ratio are different in portfolios classified by technology valuation index. Secondly, the growth rate of operating income is different in portfolios classified by technology valuation index. Finally, this study has shown that technology valuation index has possibility which it use the predictive variables of ventures' performances.

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Index Graph : An IR Index Structure for Dynamic Document Database (인덱스 그래프 : 동적 문서 데이터베이스를 위한 IR 인덱스 구조)

  • 박병권
    • The Journal of Information Systems
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    • v.10 no.1
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    • pp.257-278
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    • 2001
  • An IR(information retrieval) index for dynamic document databases where insertion, deletion, and update of documents happen frequently should be frequently updated. As the conventional structure of IR index is, however, focused on the information retrieval purpose, its structure is inefficient to handle dynamic update of it. In this paper, we propose a new structure for IR Index, we call it Index Graph, which is organized by connecting multiple indexes into a graph structure. By analysis and experiment, we prove the Index Graph is superior to the conventional structure of IR index in the performance of insertion, deletion, and update of documents as well as the performance of information retrieval.

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