• 제목/요약/키워드: a performance index

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

  • 정종철;이범석;허건수
    • 대한기계학회논문집A
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    • 제26권10호
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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.

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

  • 김동현
    • 한국전자통신학회논문지
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    • 제10권2호
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    • pp.275-282
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    • 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.

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
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    • 제23권4_2호
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    • pp.675-682
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    • 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.

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

  • 서영덕
    • 한국공간정보시스템학회 논문지
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    • 제7권2호
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    • pp.81-89
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    • 2005
  • 디클러스터링과 병렬 색인 구조는 효과적인 대용량 데이터의 검색을 위한 데이터베이스의 중요한 연구 분야이다. 기존의 연구에서 다중 디스크에서 다양한 방법들을 이용하여 R-tree등의 색인을 위한 다양한 방법들이 제시되었으나, 이에 적절한 검색 기법에 관한 연구는 거의 없었다. 이 연구에서는 기존의 연구에서 제시된 병렬 공간 색인 구조에서 검색 성능을 향상시킬 수 있는 새로운 검색 기법을 제시한다. 제시된 기법은 디스크로부터 동시에 여러 개의 노드를 읽어 들일 수 있는 병렬 디스크의 장점을 최대한 활용한 기법이다. 기존의 한번에 한 노드를 읽는 알고리즘을 개선하여 여러 노드를 동시에 접근하기 위한 최적화된 기법이다 실험을 통하여 제시된 기법은 기존의 연구에서 제시된 알고리즘들을 검색 기법의 변경을 통하여 최대 40%이상의 성능 향상을 유발함을 입증하였다.

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선박 자동조타 시스템의 성능평가지수에 관한 고찰 (On a Performance Index of Automatic Steering System of Ships)

  • 손경호;이경우
    • 대한조선학회논문집
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    • 제32권4호
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    • pp.27-37
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    • 1995
  • 본 연구에서는 대양을 항행하는 선박의 자동조타 시스템의 정량적 평가, 해석을 위해서 추진 에너지 손실의 관점에서 성능평가지수를 도출하였다. 그 결과 성능평가지수는 침로편차, 타각, 회두각속도의 제곱평균치로써 구성됨을 밝혔고, 아울러 각 제곱평균치의 계수는 선박의 유체역학적 특성에 의해서 결정됨을 알 수 있었다. 또한 성능평가지수는 자동조타 시스템에 불규칙 외란이 입력으로 작용하였을 때, 주파수 응답법과 시뮬레이션 기법에 의해서 정도 높게 계산될 수 있음을 밝혔다. 대표적 해상 상태에서 광석운반선과 소형 어선에 대한 시계산 결과, 주파수 응답법은 작은 외란하에서 시스템이 선형인 경우에는 유용하지만, 비교적 큰 외란하에서 또는 시스템 내부에 비선형 요소가 있는 경우에는 시뮬레이션 기법이 보다 정확하고 유용함을 알 수 있었다.

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균형성과표(BSC)개념을 적응한 학교급식 운영성과 측정지표 개발 (Development of Performance Indicators Based on Balanced Score Card for School Food Service Facilities)

  • 곽동경;장혜자;송지영
    • 대한지역사회영양학회지
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    • 제10권6호
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    • pp.905-919
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    • 2005
  • This study raised the necessity of developing performance indicators for measuring the management efficiency and effectiveness of school food service, and as a means of helping its implementation, a balanced score card (BSC) approach developed by Norton and Kaplan was adopted. This study established BSC in seven phases through literature: Phase 1 Defining a school food service and the scope of working activities, Phase 2 Establishing the vision of a school food service, Phase 3 Setting strategic goals, Phase 4 Identifying critical success factors (CSFs), Phase 5 Developing Key Performance Indicators (KPIs), Phase 6 Extracting cause and effect relationship, and Phase 7 Completing a preliminary BSC. The preliminary BSC was fumed into a survey, which was administered to food service related people working at the Office of Education and School Food Service including 16 offices,209 dietitians, 48 school administrators both from self-operated and contract-managed, and 9 experts in areas related to school food service. They were asked questions about strategies from 4 different perspectives,12 CSFs, 39 KPls, and the cause and effect relationships among them. As a result, among the CSFs based on 4 different perspectives, all factors other than ' zero sum on profit/loss ' from the financial perspective turned out to be valid. In terms of KPIs, manufacturing cost percentages, casualty loss count/reduction rates, school foodervice participation rates, and sales goal achievement rates were found to be valid from the financial perspective, while student satisfaction index, faculty satisfaction index, leftover ratio, nutrition educational performance count, index of evaluating nutrition education, customer claim count/reduction rate, handling customer claim count/reduction rate, and parent satisfaction index were found to be valid from the customers' perspective. Besides, nutritional requirement sufficient ratio, nutritional management score, food poisoning outbreak count, employee safety accident count, sanitary inspection assessment index, meals per labor hour (productivity index), computerization ratio, operational management index, and purchase management assessment index were also found to be valid from the perspective of internal business processes. From the perspective of innovation and learning, employee turnover ratio/rate of absenteeism, annual education and training count, employee satisfaction index, human resource management assessment index, annual menu-related customer feedback, food service information index for employees and parents/schools were also found to be valid. The significance of this study is to present indices for measuring overall performance of school lunch food service operations without putting any limitation on types of school food service management, and to help correctly assess the contribution of the current types of school food service management to schools and students. (Korean J Community Nutrition 10(6) : $905\∼919$, 2005)

A Study on Transient Grounding Performance of Ground Rods

  • Yun Dong-Hyeon;Lee Hyeong-Su;Lee Gwan Hyeong
    • 한국산업안전학회:학술대회논문집
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    • 한국안전학회 2002년도 추계 학술논문발표회 논문집
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    • pp.281-285
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    • 2002
  • Although DC ground resistance is a good index of performance for a grounding system, it does not reflect the grounding performance during the transient states. Besides, impulse ground impedance, which is defined by a ratio of the peak value of transient ground potential rise to the peak value of impulse current, cannot be an absolute performance index due to its dependence on impulse current shape. In this paper, a grounding performance of needle-typed ground rod has been compared with simple ground rod using HIFREQ[1], which is an engineering electro-magnetic code based on MoM (Method of Moment).

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병원특성 변수에 경영성과 판별력에 관한 연구 : 우리나라 종합병원을 중심으로 (A Study on the Factors of Managerial Performance in General Hospitals)

  • 류규수
    • 보건행정학회지
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    • 제5권1호
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    • pp.132-160
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    • 1995
  • This study purported to acquire information necessary to improve the management of general hospitals. It tried to determine major indices which represent managerial performance of general hospitals and to identify the managerial characteristics of general hospitals which affect the major financial indices. Eighty-eight hospitals were chosen from 188 hospitals which were subject to standardization audit by the Korean Hospital Association. The results of a discriminant analysis are summarized as followings. First, when a single index was used to measure managerial performance of the sample hospitals, the ration of net profit to total capital was the best index and its discriminant power was 58.14%. The ratio of the number of boardmen((M. D.) and average daily medical cost were highly related to this index. Second, when two indices were used, income growth rte and the ration of net profit to total capital had the highest discriminant distinction ability. Their discriminant power was 61.9%. In this case, the ratio of the number of boardmen(M. D.) was significantly and highly related to the indices. Third, when all three indices-income growth rate, the ration of net profit to total capital and quick ratio - were used together, a discriminant function was statistically insignificant. Therefore, using all three indices was not useful in measuring managerial performance of the sample hospitals. In conclusion, using two indices-income growth rate and the ration of net profit to total capital-was better in measuring manegerial performance of general hospitals than using a single index. The independent variable which affected these indices was the ration of the number of boardmen. The discriminant function was : $D_{GI}=2.77+4.832\times(the ratio of the number of boardmen)$ *G=growth index(income growth rate) *I=profit index(the ration of net profit to total capital)

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성능 함수를 고려한 실시간 제어 테스크에서의 최적 체크 포인터 구간 선정 (Determination of Optimal Checkpoint Interval for Real-time Control Tasks Considering Performance Index Function)

  • 곽성우;정용주
    • 전기학회논문지
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    • 제57권5호
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    • pp.875-880
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    • 2008
  • In this paper, a novel method to determine the optimal checkpoint interval for real-time control task is proposed considering its performance degradation according to tasks's execution time. The control task in this paper has a specific sampling period shorter than its deadline. Control performance is degraded as the control task execution time is prolonged across the sampling period and eventually zero when reached to the deadline. A new performance index is defined to represent the performance variation due to the extension of task execution time accompanying rollback fault recovery. The procedure to find the optimal checkpoint interval is addressed and several simulation examples are presented.

화재 시 연소성 물질에 대한 화재 위험성 등급 평가 (Rating Evaluation of Fire Risk for Combustible Materials in Case of Fire)

  • 정영진;진의
    • 공업화학
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    • 제32권1호
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    • pp.75-82
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    • 2021
  • 본 연구는 건자재용 목재 및 플라스틱의 화재위험성 평가에 대하여 새로 고안된 화재성능지수-III (FPI-III), 화재성장지수-III (FGI-III), 화재위험성지수-IV (FRI-IV)를 중심으로 조사하였다. 시험편은 삼나무, 적송, PMMA, PVC를 사용하였다. 화재 특성은 시험편에 대하여 콘칼로리미터(ISO 5660-1) 장비를 이용하여 조사하였다. 연소반응 후 측정된 화재성능지수-III는 PMMA를 기준으로 1.0~15.0으로 나타났다. 화재성능지수-III에 의한 화재위험성은 PVC, 적송, 삼나무, PMMA 순서로 증가하였다. 화재성장지수-III는 PMMA를 기준으로 0.5~3.3으로 나타났다. 화재성장지수-III에 의한 화재위험성은 PVC, PMMA, 적송, 삼나무의 순서로 증가하였다. 모든 시편의 CO 피크농도는 106~570 ppm으로 측정되었다. 결론적으로 체적밀도가 낮은 삼나무와 PMMA와 같이 휘발성 유기물질을 다량 함유한 재료는 화재성능지수-III가 낮고, 화재성장지수-III가 높으므로 화재로 인한 화재위험성이 높은 것으로 이해된다. 이는 화재위험성지수-IV와 일치하였다.