• 제목/요약/키워드: fit testing

검색결과 336건 처리시간 0.029초

휴대용 계기용변성장치 고장 및 측정장치 개발 (A Development of portable equipment for testing Metering Out Fit)

  • 조성현
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2007년도 제38회 하계학술대회
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    • pp.673-674
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    • 2007
  • 22.9KV-Y 배전선로의 특고압 수전설비에 계량장치로 부설되어 운영중인 계기용변성기 M.O.F(Metering Out Fit)는 계기용변압기와 계기용변류기를 하나의 상자 속에 수납한 것으로 전력량계와 조합시켜서 전력측정의 변성장치로 사용되고 있다. 계량장치로 사용되고 있는 계기용변성기는 고객과 공정거래확립을 위하여 상시 정해진 비오차 특성을 만족하여야 한다. 그러나 고객구내 수전설비에서 파급고장이 발생시 과전류로 인하여 계기용변성기의 권선에 큰 충격이 가해져 비오차 특성에 문제점이 발생하나, 이 비오차를 측정할 때는 현재 정전상태에서 측정이 가능하여 현실적으로 측정을 할 수 없다. 이에 전기를 사용하는 활선상태에서도 비오차 측정을 할 수 있는 개발품에 대하여 고찰하고자 한다.

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교량의 경험적 손상도 곡선 (Empirical Fragility Curves for Bridge)

  • 이종헌;김운학;최정호
    • 한국구조물진단유지관리공학회 논문집
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    • 제6권1호
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    • pp.255-262
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    • 2002
  • This paper presents a statistical analysis of empirical fragility curves for bridge. The empirical fragility curves are developed utilizing bridge damage data obtained from the 1995 Hyogoken Nanbu(Kobe) earthquake. Two-parameter lognormal distribution functions are used to represent the fragility curves with the parameters estimated by the maximum likelihood method. This paper also presents methods of testing the goodness of fit of the fragility curves and estimating the confidence intervals of the two parameters(median and log-standard deviation) of the distribution. An analytical interpretation of randomness and uncertainty associated with the median is provided.

국내 MIS 연구에서 구조방정식모형 활용에 관한 메타분석 (A Meta Analysis of Using Structural Equation Model on the Korean MIS Research)

  • 김종기;전진환
    • Asia pacific journal of information systems
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    • 제19권4호
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    • pp.47-75
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    • 2009
  • Recently, researches on Management Information Systems (MIS) have laid out theoretical foundation and academic paradigms by introducing diverse theories, themes, and methodologies. Especially, academic paradigms of MIS encourage a user-friendly approach by developing the technologies from the users' perspectives, which reflects the existence of strong causal relationships between information systems and user's behavior. As in other areas in social science the use of structural equation modeling (SEM) has rapidly increased in recent years especially in the MIS area. The SEM technique is important because it provides powerful ways to address key IS research problems. It also has a unique ability to simultaneously examine a series of casual relationships while analyzing multiple independent and dependent variables all at the same time. In spite of providing many benefits to the MIS researchers, there are some potential pitfalls with the analytical technique. The research objective of this study is to provide some guidelines for an appropriate use of SEM based on the assessment of current practice of using SEM in the MIS research. This study focuses on several statistical issues related to the use of SEM in the MIS research. Selected articles are assessed in three parts through the meta analysis. The first part is related to the initial specification of theoretical model of interest. The second is about data screening prior to model estimation and testing. And the last part concerns estimation and testing of theoretical models based on empirical data. This study reviewed the use of SEM in 164 empirical research articles published in four major MIS journals in Korea (APJIS, ISR, JIS and JITAM) from 1991 to 2007. APJIS, ISR, JIS and JITAM accounted for 73, 17, 58, and 16 of the total number of applications, respectively. The number of published applications has been increased over time. LISREL was the most frequently used SEM software among MIS researchers (97 studies (59.15%)), followed by AMOS (45 studies (27.44%)). In the first part, regarding issues related to the initial specification of theoretical model of interest, all of the studies have used cross-sectional data. The studies that use cross-sectional data may be able to better explain their structural model as a set of relationships. Most of SEM studies, meanwhile, have employed. confirmatory-type analysis (146 articles (89%)). For the model specification issue about model formulation, 159 (96.9%) of the studies were the full structural equation model. For only 5 researches, SEM was used for the measurement model with a set of observed variables. The average sample size for all models was 365.41, with some models retaining a sample as small as 50 and as large as 500. The second part of the issue is related to data screening prior to model estimation and testing. Data screening is important for researchers particularly in defining how they deal with missing values. Overall, discussion of data screening was reported in 118 (71.95%) of the studies while there was no study discussing evidence of multivariate normality for the models. On the third part, issues related to the estimation and testing of theoretical models on empirical data, assessing model fit is one of most important issues because it provides adequate statistical power for research models. There were multiple fit indices used in the SEM applications. The test was reported in the most of studies (146 (89%)), whereas normed-test was reported less frequently (65 studies (39.64%)). It is important that normed- of 3 or lower is required for adequate model fit. The most popular model fit indices were GFI (109 (66.46%)), AGFI (84 (51.22%)), NFI (44 (47.56%)), RMR (42 (25.61%)), CFI (59 (35.98%)), RMSEA (62 (37.80)), and NNFI (48 (29.27%)). Regarding the test of construct validity, convergent validity has been examined in 109 studies (66.46%) and discriminant validity in 98 (59.76%). 81 studies (49.39%) have reported the average variance extracted (AVE). However, there was little discussion of direct (47 (28.66%)), indirect, and total effect in the SEM models. Based on these findings, we suggest general guidelines for the use of SEM and propose some recommendations on concerning issues of latent variables models, raw data, sample size, data screening, reporting parameter estimated, model fit statistics, multivariate normality, confirmatory factor analysis, reliabilities and the decomposition of effects.

작업 강도가 방진 마스크의 밀착도와 감성품질에 미치는 영향 (Effect of Work Intensity on Fit Factor and Affecive Quality of Dustproof Mask)

  • 이진실;조선희;윤정민;김민선;박재규;최재호
    • 품질경영학회지
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    • 제46권2호
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    • pp.301-310
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    • 2018
  • Purpose: The purpose of this study is to investigate the effect of work intensity on fit factor and affective quality of the dustproof Background: Among the victims who suffer pneumoconiosis due to the inhalation of toxic substances or the lack of oxygen during the work, the proportion of the victims is larger than the other causes. Wearing a respirator may prevent pneumoconiosis, but it can be hazardous to workers because of the leakage through filters, cartridges, exhaust valves, broken parts, and face-to-face contact. Despite leakage through the contact area between the mask and the face has various causes such as the wearer's activity, sweat accumulation, facial shape, etc., There is a lack of relevant research and regulation compared to developed countries that have already institutionalized the law 30 years ago and give the right to sell through a test Method: The work intensity was adjusted by walking or running at 6km/h and 11km/h on the treadmill, and tasks were defined with reference to the test procedure and the exercise sequence applied in the face leakage test of the dustproof mask. And fit factor was measured objectively using 'Respirator Fit Tester 8038' which measures fit factor calculated by dividing the number of dust present outside the mask by inside the mask. In addition, affective quality was classified by the ease of use, ease of breathing, and ease of wearing, and was measured using the 5-point likert scale questionnaire. Results: There was a significant difference in fit factor, ease of breathing, and wearing convenience according to work intensity and no significant difference in ease of use(${\alpha}=0.01$). And when the work intensity was high, fit factor, ease of breathing, and wearing convenience were all lower than when the work intensity was low. Conclusion: In Korea, it is necessary to consider consideration of the work intensity when testing the leakage rate of the face part for safety certification of the respiratory protective equipment, When developing a mask, it should be possible to maintain high adhesion even under intense, active situation and high temperature conditions by selecting materials, improving the wearing style, and expanding the adjustable range.

Cumulative Sums of Residuals in GLMM and Its Implementation

  • Choi, DoYeon;Jeong, KwangMo
    • Communications for Statistical Applications and Methods
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    • 제21권5호
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    • pp.423-433
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    • 2014
  • Test statistics using cumulative sums of residuals have been widely used in various regression models including generalized linear models(GLM). Recently, Pan and Lin (2005) extended this testing procedure to the generalized linear mixed models(GLMM) having random effects, in which we encounter difficulties in computing the marginal likelihood that is expressed as an integral of random effects distribution. The Gaussian quadrature algorithm is commonly used to approximate the marginal likelihood. Many commercial statistical packages provide an option to apply this type of goodness-of-fit test in GLMs but available programs are very rare for GLMMs. We suggest a computational algorithm to implement the testing procedure in GLMMs by a freely accessible R package, and also illustrate through practical examples.

Improved Exponential Software Reliability Model Based on NHPP with the Uncertainty of Operating Environments

  • Song, Kwang Yoon;Chang, In Hong
    • 통합자연과학논문집
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    • 제10권4호
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    • pp.249-257
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    • 2017
  • The main focus when developing software is to improve the reliability and stability of a software system. We are enjoying a very comfortable life thanks to modern civilization, however, comfort is not guaranteed to us. Once software systems are introduced, the software systems used in the field environments are the same as or close to those used in the development-testing environment; however, the systems may be used in many different locations. Development of software system is a difficult and complex process. Generally, existing software reliability models are applied to software testing data and then used to make predictions on the software failures and reliability in the field. In this paper, we present an improved exponential NHPP software reliability model in different development environments, and examine the goodness-of-fit of improved exponential model and other model based on two datasets. The results show that the proposed model fits significantly better than other NHPP software reliability model.

노년층을 위한 스마트 재킷의 개발 및 평가 - 미국 여성을 대상으로 - (Development and Analysis of Smart Jacket for the Elderly -Focused on American Women-)

  • 백경자;수잔 애쉬다운
    • 한국의류산업학회지
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    • 제11권2호
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    • pp.315-325
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    • 2009
  • 본 연구에서는 시판 중인 디바이스를 활용하여 외관에서는 기성복의 스타일을 유지하면서 기능성을 부여한 노년 여성을 위한 스마트 재킷을 개발하였다. 노년기에 접어들면서 시력은 약화되며 효과적인 체온조절도 저하된다. 이에 열과 빛의 기능을 제공하는 연구재킷을 제작하고 노년층 소비자들의 평가를 실시하여 그 수용가능성을 확인하고자 하였다. 재킷에 대한 만족도 평가는 전문가 외관 평가 및 소비자 착용 평가로 실시되었으며 재킷의 피트성, 활동성, 디바이스의 기능성, 수용 가능성 여부 등을 평가하였다. 그 결과, 전반적으로 높은 만족도를 보였으며 노년층에서도 충분히 미적요소와 기능성이 결합된 스마트 의류가 일상복으로 받아들여질 수 있음을 알 수 있었다. 그러나 여전히 스마트 의류의 문제점 중의 하나인 디바이스의 무게를 경량화 할 수 있는 방법이 모색되어야 할 것으로 나타났으며, 이러한 결과가 노년층을 위한 스마트 의복의 가능성과 만족도 향상을 위한 방안을 제시하는 기초 자료가 되기를 바란다.

변화점을 갖는 불완전수정 소프트웨어 신뢰도 성장모형 연구 (An Imperfect Debugging Software Reliability Growth Model with Change-Point)

  • 남경현;김도훈
    • 품질경영학회지
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    • 제34권4호
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    • pp.133-138
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    • 2006
  • In this paper, we propose a software reliability growth model (SRGM) based on the testing domain, which is isolated by the executed test cases. This model assumes an imperfect debugging environment in which new faults are introduced in the fault-correction process. We consider that the fault detection rate of NHPP model is changed in the proposed SRGM. We obtain the maximum likelihood estimate, and compare goodness-of-fit with another existing software reliability growth model.

전해 캐패시터의 최적 가속시험방법과 수명예측 (The best accelerated method and lifetime prediction of electrolytic capacitors)

  • 김하나;심찬호;김성준;윤중락;이헌용
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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    • pp.1945-1947
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    • 2005
  • This study considers find out best accelerated life testing and lifetime prediction of electrolytic capacitors. We proved about relation between failure and deterioration mechanism from last thesis. Beside we performed test that temperature and voltage press higher than allowance specification. Failure distribution acquired from those test. And wiebull function and Minitab program applied to accelerated constant and lifetime by means of calculation. At the result, goodness of fit affect to weibull function and acceleration factor therefore fitting is important factor in reliability testing.

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통신케이블 차폐시험방법의 유효성 확인 및 측정불확도 추정 (Validation and Measurement Uncertainty Estimation in the Testing Method of Cable-harness Shielding Effectiveness)

  • 김종상;조남호
    • 한국컴퓨터정보학회논문지
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    • 제7권1호
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    • pp.8-19
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    • 2002
  • 시험기관은 표준화되지 않은 시험방법. 해당기관이 설계/개발한 방법 등에 의한 시험을 수행할 경우 방법의 유효성이 확인되어야만 사용할 수 있으며, 또한 측정값에 대한 불확도(Uncertainty)의 추정이 요구되고 있다. 따라서 케이블-하네스의 EMI 차폐효과시험방법에 대한 측정정밀도를 통계적 분석 방법 에 의거 검토하여 유효성을 확인하는 방법을 제시하고 시험결과에 대한 측정불확도를 추정하는 방법을 제시하였다.

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