• 제목/요약/키워드: performance index

검색결과 4,612건 처리시간 0.037초

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

  • 박병권
    • 한국정보시스템학회지:정보시스템연구
    • /
    • 제10권1호
    • /
    • pp.257-278
    • /
    • 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.

  • PDF

NAND 플래쉬메모리에서 고정그리드화일 색인의 성능 평가 (Performance Evaluation of Fixed-Grid File Index on NAND Flash Memory)

  • 김동현
    • 한국전자통신학회논문지
    • /
    • 제10권2호
    • /
    • pp.275-282
    • /
    • 2015
  • NAND 플래쉬메모리는 전원이 꺼져도 데이터를 유지할 수 있고 저비용, 고용량의 특징을 가지기 때문에 휴대용 기기에서 많이 활용되고 있다. 플래쉬메모리에서 대용량의 데이터를 효과적으로 처리하기 위하여 색인을 필수적으로 사용해야 한다. 그러나 플래쉬메모리는 쓰기 연산의 비용이 크고 덮어쓰기 연산을 지원하지 않기 때문에 기존의 디스크기반 색인을 사용하면 성능이 저하되는 문제가 발생할 수 있다. 본 논문에서는 플래쉬메모리에서 고정그리드화일 색인을 구현하고 다양한 조건에서 성능 평가를 수행한다. 이를 위하여 질의연산과 변경 연산의 비율에 따른 평균 수행 시간을 측정한다. 그리고 디스크에서의 수행 시간과 비교한다.

상변화 냉각시스템의 정량적 성능지수 연구 (A Study on Quantitative Performance Index for Phase-Change Cooling Systems)

  • 장명언;송혜은
    • 한국군사과학기술학회지
    • /
    • 제23권3호
    • /
    • pp.237-245
    • /
    • 2020
  • In this paper, I introduce Phase-Change Cooling for thermal management of high power devices that can be applied to High Power Laser and Electric Propulsion Systems which are composed of multiple distributed superheat sources. Phase-Change Cooling can be good used to efficient cooling of their heat sources. Phase-Change Cooling has extremely high efficiency of two-phase heat transport by utilizing heat of vaporization, relatively low flow rates and reduced pumps power. And I suggest TPI(Thermal Performance Index) which is a quantitative performance index of Phase-Change Cooling for thermal management. I quantify the performance of Phase-Change Cooling by introducing TPI. I present the test results of TPI's changing refrigerant, heat sink and flow rate of the Phase-Change Cooling system through the experiments and analyze these results.

평가지표에 따른 제어기 설계 영향 분석 (A Analysis on the Effect of the Controller Design due to Performance Index)

  • 유항열;이정국;이금원;이준모
    • 한국조명전기설비학회:학술대회논문집
    • /
    • 한국조명전기설비학회 2004년도 춘계학술대회 논문집
    • /
    • pp.90-94
    • /
    • 2004
  • Among various modern control theories, PID control has been well used for several decades. PID algorithms needs son tuning methods 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 meets some specifications. In this paper, linear conbinational type of performance using error signal, time, control input and robustness is used to the PID control of air conditioning system. By the 2 DOF PID parmeters minimizing perfromacne index, controllers, output characteristics and robustness properties are analyzed. Simulations are done with MATLAB m file and mdl files.

  • PDF

A HYPOTHESIS TESTING PROCEDURE OF ASSESSMENT FOR THE LIFETIME PERFORMANCE INDEX UNDER A GENERAL CLASS OF INVERSE EXPONENTIATED DISTRIBUTIONS WITH PROGRESSIVE TYPE I INTERVAL CENSORING

  • KAYAL, TANMAY;TRIPATHI, YOGESH MANI;WU, SHU-FEI
    • Journal of applied mathematics & informatics
    • /
    • 제37권1_2호
    • /
    • pp.105-121
    • /
    • 2019
  • One of the main objective of manufacturing industries is to assess the capability performance of different processes. In this paper, we use the lifetime performance index $C_L$ as a criterion to measure larger-the-better type quality characteristic for evaluating the product performance. The lifetimes of products are assumed to follow a general class of inverted exponentiated distributions. We use maximum likelihood estimator to estimate the lifetime performance index under the assumption that data are progressive type I interval censored. We also obtain asymptotic distribution of this estimator. Based on this estimator, a new hypothesis testing procedure is developed with respect to a given lower specification limit. Finally, two numerical examples are discussed in support of the proposed testing procedure.

Group-indexed orthogonal frequency division multiplexing index modulation aided performance trade off

  • Anushya, Thomas Wilfred Edison Athisaya;Laxmikandan, Thangavelu;Manimekalai, Thirunavukkarasu
    • ETRI Journal
    • /
    • 제44권1호
    • /
    • pp.105-116
    • /
    • 2022
  • In this study, a novel group-indexed orthogonal frequency division multiplexing index modulation (OFDM-IM) scheme is proposed to achieve a tradeoff between spectral efficiency (SE) and bit-error-rate (BER) performance. In the proposed scheme, the total subcarriers in a group are divided into subgroups, and additional bits are transmitted by subgroup indexing, unlike the conventional OFDM-IM scheme, which uses index bits to select active subcarriers. With the proposed scheme, the additional degree of freedom provided by the number of active subgroups selected provides a tradeoff between spectral efficiency and BER performance. Decoding is performed in steps to reduce computional complexity in the decoder design. Simulaton results show that the number of active subgroups selected influences the proposed scheme's performance in terms of energy efficiency, spectral efficiency, and BER performance.

비용/공정/위험 통합 관점에서 메가 프로젝트 성과측정을 위한 위험성과지수 개발 (A Development of Risk Performance Index for Mega-project Performance Measurement in view of the integrated Cost/Schedule/Risk)

  • 김선규;박규영;유영정
    • 한국건설관리학회논문집
    • /
    • 제10권1호
    • /
    • pp.69-77
    • /
    • 2009
  • 최근 도심재생사업에 대한 관심과 연구가 활발히 진행되고 있다. 이는 기존 도시의 노후화된 건물과 저급화된 기반시설로 인해 파생되는 사회적 경제적 문제들을 새로운 도시개발 즉 재개발사업을 통해 해결하려는 노력의 일환이다. 그러나 도심재생사업은 사업에 관계되는 다양하고 복잡한 이해관계자들과 규모의 방대함으로 수많은 위험에 노출되어 있어 사업의 성과를 보장할 수 없다는 특징을 가지고 있다. 본 연구는 도심재생사업과 같은 메가 프로젝트의 성과관리를 함에 있어, 기존의 비용/공정 중심의 성과측정체계를 위험관리 관점으로 확장시킴으로서 메가 프로젝트에 대한 종합 성과관리의 효율성을 향상시키기 위한 목적으로 위험성과지수 방법론을 제시하였다. 본 연구에서 제시한 위험성과지수 방법론은 기존의 EVMS와 유사한 체계를 갖추고 있고, 위험성과지수를 구성하는 18종류의 세부지수와 변수를 통해 비용/공정/위험의 3차원적 통합 성과관리가 가능하게 하였다.

와이어쏘 공정에서 다이아몬드 입자의 인성지수가 절단 성능에 미치는 영향 (Effect of Toughness Index of Diamond Abrasives on Cutting Performance in Wire Sawing Process)

  • 김도연;이태경;김형재
    • 한국산업융합학회 논문집
    • /
    • 제23권4_2호
    • /
    • pp.675-682
    • /
    • 2020
  • Multi-wire sawing is the prominent technology employed to cut hard material ingots into wafers. This paper aimed to research the effect of diamond toughness index on the cutting performance of electroplated diamond wire. Three different toughness index of diamond abrasives were used to manufacture electroplated diamond wires. The cutting performance of electroplated diamond wire is verified through experiments, in which sapphire ingot are cut using single wire sawing machine. A single wire saw for constant load slicing is developed for the cutting performance evaluation of electroplated diamond wire. Choosing the cutting depth, total cutting depth, cutting force and wear of electroplated diamond wires as evaluation parameters, the performance of electroplated diamond wire is evaluated. The results of this study showed that there was a significant direct relationship between the toughness index of diamond abrasives and the cutting performance. Results demonstrated that diamond abrasive with a high toughness index showed higher cutting performance. However, all diamond abrasives showed similar cutting performance under low load conditions. The results of this paper are useful for the development of cutting large diameter ingots and cutting high hardness ingots at high speed.

Structural damage detection using a damage probability index based on frequency response function and strain energy concept

  • Bagherahmadi, Seyed Ahdiye;Seyedpoor, Seyed Mohammad
    • Structural Engineering and Mechanics
    • /
    • 제67권4호
    • /
    • pp.327-336
    • /
    • 2018
  • In this study, an efficient damage index is proposed to identify multiple damage cases in structural systems using the concepts of frequency response function (FRF) matrix and strain energy of a structure. The index is defined based on the change of strain energy of an element due to damage. For obtaining the strain energy stored in elements, the columnar coefficients of the FRF matrix is used. The new indicator is named here as frequency response function strain energy based index (FRFSEBI). In order to assess the performance of the proposed index for structural damage detection, some benchmark structures having a number of damage scenarios are considered. Numerical results demonstrate that the proposed index even with considering noise can accurately identify the actual location and approximate severity of the damage. In order to demonstrate the high efficiency of the proposed damage index, its performance is also compared with that of the flexibility strain energy based index (FSEBI) provided in the literature.

An Index Structure for Main-memory Storage Systems using The Level Pre-fetching

  • Lee, Seok-Jae;Yoon, Jong-Hyun;Song, Seok-Il;Yoo, Jae-Soo
    • International Journal of Contents
    • /
    • 제3권1호
    • /
    • pp.19-23
    • /
    • 2007
  • Recently, several main-memory index structures have been proposed to reduce the impact of secondary cache misses. In mainmemory storage systems, secondary cache misses have a substantial effect on the performance of index structures. However, recent studies still stiffer from secondary cache misses when visiting each level of index tree. In this paper, we propose a new index structure that minimizes the total amount of cache miss latency. The proposed index structure prefetched grandchildren of a current node. The basic structure of the proposed index structure is based on that of the CSB+-Tree, which uses the concept of a node group to increase fan-out. However, the insert algorithm of the proposed index structure significantly reduces the cost of a split. The superiority of our algorithm is shown through performance evaluation.