• Title/Summary/Keyword: Estimate Criteria

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The relationship analysis in VDT of work hours (VDT 작업시간의 관련성 분석)

  • Kang, Jeom-Deok
    • The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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    • v.9 no.1
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    • pp.19-28
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    • 2003
  • Objectives : This study was to investigate the relationship analysis in VDT(visual display terminal) of work hours. Methods : Questionnaires were completed by 41 women in VDT operations. The information was used to estimate multiple regression for the VDT of work hours related factors association. Results : The prevalence of the VDT of work hours was significantly higher in the shoulder which followed by the neck, the hand and fingers, the arms, the lowback, the back. The VDT of work hours decreased with aging. The VDT of work hours increased with work duration, single, lower among habitual exercise. The desk height, the seat pan height, the posture on the sitting, the elbow angle all did not meet the recommended criteria. Conclusions : Data from this study support a statistically significant association with satisfaction for occupation.

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Determination of Performance Indicator Thresholds Based on Typical PSA Results

  • Kang, Dae-Il;Kim, Kil-Yoo;Hwang, Mee-Jung;Sung, Key-Yong
    • Nuclear Engineering and Technology
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    • v.36 no.6
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    • pp.485-496
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    • 2004
  • Typical probabilistic safety assessment (PSA) results were used to estimate the performance indicator (PI) thresholds of unplanned reactor scram (URS) and safety system unavailability (SSU) for Korean nuclear power plants (NPPs). The changes in core damage frequency (${\Delta}$CDFs) of $10^{-6}/yr$, $10^{-5}/yr$, and $10^{-4}/yr$ were adopted as the risk criteria in setting up the PI thresholds. The PI thresholds for the URS were estimated using information pertaining to the initiating event frequencies, the CDF, and the CDF contribution of each initiating event. The PI thresholds of the SSU were estimated using information on the unavailability, the Fussell-Vesely importance, and the CDF.

A Study on the Measurement of Contact Force of Pantograph on High Speed Train

  • Seo Sung-Il;Cho Yong-Hyun;Mok Jin-Yong;Park Choon-Soo
    • Journal of Mechanical Science and Technology
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    • v.20 no.10
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    • pp.1548-1556
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    • 2006
  • Appropriate contact force is required for the pantograph on the high speed train to collect current from the catenery system without separation. However, at high speed, large aerodynamic lifting force is generated by the contact plate and the body of pantograph, which may cause wear of the contact wire. In this study, to confirm the interface performance of the pantograph on Korea High Speed Train, a method to measure the contact force of the pantograph was proposed and the related measuring system was developed. The forces acting on the pantograph were clarified and a practical procedure to estimate the forces was proposed. A special device was invented and applied to measure the aerodynamic lifting force. Measured contact forces were displayed by the developed system and evaluated based on the criteria.

An Evaluation of the Effect of Internal Thinning Defect on the Failure Pressure of Elbow (곡관의 손상압력에 미치는 내부 감육결함의 영향 평가)

  • Kim, Jin-Weon;Kim, Tae-Soon;Park, Chi-Yong
    • Journal of the Korean Society of Safety
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    • v.18 no.4
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    • pp.28-34
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    • 2003
  • In the present study, three-dimensional finite element analysis was performed to investigate the effects of internal wall thinning defect on the failure pressure of elbow in the piping system and to develop the failure pressure evaluation model. From the results of finite element analysis, the failure pressure was derived by employing local stress criteria, and the effects of thinning location, bend radius, and defect geometry on the failure pressure of internally wall thinned elbow were investigated. Also, based on these investigations and previous model developed to estimate the failure pressure of elbow with an external pitting defect, the failure pressure evaluation model to be applicable to the elbow containing an internal thinning defect was proposed and compared with the results of finite element analysis. The failure pressure calculated by the model agreed well with the results of finite element analysis.

A Multi-Expression Programming Application to the Design of Planar Antennae

  • Braunstein, Jeffrey;Kim, Hyeong-Seok;Kahng, Sung-Tek
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1589-1590
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    • 2006
  • A method to determine functional relationships between the variable physical dimensions of an antenna and the antenna performance characteristics is presented. By applying multi-expression programming (MEP) to this data set, optimization with regard to a given criteria can be subsequently performed on the functions instead of performing repealed electromagnetic simulations. The functionals are trained on an initial population of simulation samples and refined using a point-wise error estimate to identify design parameters for subsequent samples. Additionally, the depth of the MEP tree is adjusted for increased accuracy as the data set is deemed sufficient.

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Study on the Inundation Risk Evaluation by the Relationship Analysis (다양한 침수인자간의 상관관계 분석을 통한 침수위험지역 예측)

  • Choi, Sung-Wook;Jun, Hwan-Don;Park, Moo-Jong
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.115-118
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    • 2008
  • In this study, PROMETHEE(Preference Ranking Organization METHod for Enrichment Evaluations) which is one of the multi criteria decision making methods is applied to estimate the relative inundation risk of the urban subcatchment. For this purpose, five factors which have an effect on the inundation risk are selected and used to perform PROMETHEE. Those are elevation average, slope average, density of conduit, population and sediment yields per unit area of each subcatchment. Based on them, PROMETHEE is performed and the relative inundation risk for each subcatchment is estimated. Sensitivity anlysis is conducted to evaluate each factor's effect on subcatchment and it is found that suggested method can be used to establish a practical guide to mitigate the inundation.

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Storage Capacity Estimation for Automated Storage/Retrieval Systems under Stochastic Demand (확률적 수요하에서의 자동창고의 필요 저장능력 추정)

  • Cho, Myeon-Sig;Bozer, Yavuz-A.
    • Journal of Korean Institute of Industrial Engineers
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    • v.27 no.2
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    • pp.169-175
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    • 2001
  • Most of studies on automated storage/retrieval (AS/R) system assumed that storage capacity is given, although it is a very important decision variable in the design phase. We propose a simple algorithm to estimate the required storage capacity, i.e., number of aisles and number of openings in vertical and horizontal directions in each aisle, of an AS/R system under stochastic demand, in which storage requests occur endogenously and exogenously while the retrieval requests occur endogenously from the machines. Two design criteria, maximum permissible overflow probability and maximum allowable storage/retrieval (S/R) machine utilization, are used to compute the storage capacity. This model can be effectively used in the design phase of new AS/R systems.

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Estimating the Number of Clusters using Hotelling's

  • Choi, Kyung-Mee
    • Communications for Statistical Applications and Methods
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    • v.12 no.2
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    • pp.305-312
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    • 2005
  • In the cluster analysis, Hotelling's $T^2$ can be used to estimate the unknown number of clusters based on the idea of multiple comparison procedure. Especially, its threshold is obtained according to the probability of committing the type one error. Examples are used to compare Hotelling's $T^2$ with other classical location test statistics such as Sum-of-Squared Error and Wilks' $\Lambda$ The hierarchical clustering is used to reveal the underlying structure of the data. Also related criteria are reviewed in view of both the between variance and the within variance.

Storage Capacity Estimation for Automated Storage/Retrieval Systems Considering Material Handling Delay (자재취급 지연을 고려한 자동창고의 저장능력 추정)

  • 조면식
    • Journal of the Korea Society for Simulation
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    • v.10 no.3
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    • pp.71-82
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    • 2001
  • Considering material handling delay which occurs between storage and processing stations, we propose an algorithm to estimate the required storage capacity, i.e., number of aisles and number of openings in vertical and horizontal directions in each aisle, of an automated storage/retrieval(AS/R) system. Due to the random nature of storage and retrieval requests, proportion of single and dual commands is not known in advance. Two design criteria, maximum permissible overflow probability and maximum allowable storage/retrieval(S/R) machine utilization, are used to compute the storage capacity. Most of studies assume that storage capacity of AS/R systems is given, although it is a very important decision variable in the design phase. Therefore, the proposed model can be effectively used in the design phase of new AS/R systems.

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Stochastic structures of world's death counts after World War II

  • Lee, Jae J.
    • Communications for Statistical Applications and Methods
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    • v.29 no.3
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    • pp.353-371
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    • 2022
  • This paper analyzes death counts after World War II of several countries to identify and to compare their stochastic structures. The stochastic structures that this paper entertains are three structural time series models, a local level with a random walk model, a fixed local linear trend model and a local linear trend model. The structural time series models assume that a time series can be formulated directly with the unobserved components such as trend, slope, seasonal, cycle and daily effect. Random effect of each unobserved component is characterized by its own stochastic structure and a distribution of its irregular component. The structural time series models use the Kalman filter to estimate unknown parameters of a stochastic model, to predict future data, and to do filtering data. This paper identifies the best-fitted stochastic model for three types of death counts (Female, Male and Total) of each country. Two diagnostic procedures are used to check the validity of fitted models. Three criteria, AIC, BIC and SSPE are used to select the best-fitted valid stochastic model for each type of death counts of each country.