• Title/Summary/Keyword: inverse power model

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Investigation of the Acceleration Coefficient in Acceleration Models (가속모델의 가속계수 조사)

  • Hyunjong Park;Sungjun Kim;Beomsik Park;Somi Park;Siil Sung
    • Journal of Korean Society for Quality Management
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    • v.52 no.1
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    • pp.135-148
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    • 2024
  • Purpose: This study is to investigate the literature on accelerated tests based on the acceleration model and to provide a compilation of results on the parameters applied in the acceleration model and the test conditions. Methods: This research is conducts a literature review on accelerated tests using the acceleration model, with a focus on test targets, test conditions, and parameter values. The study is organizing the results of this literature review to facilitate their application in the design of reliability tests. Results: A literature review investigated a variety of test targets, test conditions, and parameter values. Conclusion: The results of the literature research conducted revealed various acceleration model parameter. Such literature research on accelerated tests can establish the foundation for reliability test design and contribute to future product development and quality improvement

Effects of changing materials properties for vibration of FGM beam using integral shear deformation model

  • Mokhtar Ellali;Mashhour A. Alazwari;Mokhtar Bouazza;Mohamed A. Eltaher;Noureddine Benseddiq
    • Coupled systems mechanics
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    • v.13 no.4
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    • pp.277-291
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    • 2024
  • The objective of this work is to study the effects of the modification of material properties on the vibration of the FGM beam using an integral shear strain model. In the present theory, the rotational displacement is replaced by an integral term in the displacement fields. The use of a shear correction factor is not necessary because our model gives a parabolic description of shear stress through the thickness while satisfying the conditions of zero shear stresses on the bottom and top surfaces of the beam. The FGM beam is assumed that the beam is a mixture of metal and ceramic, and that its properties change depending on the power functions of the thickness of the beam such as: linear, quadratic, cubic and inverse quadratic. By applying Hamilton's principle, general formulas were obtained to obtain the frequencies of the FGM beam. The effects of changing compositional characteristics of materials presented by volume fraction of FGM beams with simply supported edges on free vibration and some mode shapes are investigated.

Comparison and Evaluation of Root Mean Square for Parameter Settings of Spatial Interpolation Method (공간보간법의 매개변수 설정에 따른 평균제곱근 비교 및 평가)

  • Lee, Hyung-Seok
    • Journal of the Korean Association of Geographic Information Studies
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    • v.13 no.3
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    • pp.29-41
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    • 2010
  • In this study, the prediction errors of various spatial interpolation methods used to model values at unmeasured locations was compared and the accuracy of these predictions was evaluated. The root mean square (RMS) was calculated by processing different parameters associated with spatial interpolation by using techniques such as inverse distance weighting, kriging, local polynomial interpolation and radial basis function to known elevation data of the east coastal area under the same condition. As a result, a circular model of simple kriging reached the smallest RMS value. Prediction map using the multiquadric method of a radial basis function was coincident with the spatial distribution obtained by constructing a triangulated irregular network of the study area through the raster mathematics. In addition, better interpolation results can be obtained by setting the optimal power value provided under the selected condition.

Analysis of Tidal Deflection and Ice Properties of Ross Ice Shelf, Antarctica, by using DDInSAR Imagery (DDInSAR 영상을 이용한 남극 로스 빙붕의 조위변형과 물성 분석)

  • Han, Soojeong;Han, Hyangsun;Lee, Hoonyol
    • Korean Journal of Remote Sensing
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    • v.35 no.6_1
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    • pp.933-944
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    • 2019
  • This study analyzes the tide deformation of land boundary regions on the east (Region A) and west (Region B) sides of the Ross Ice Shelf in Antarctica using Double-Differential Interferometric Synthetic Aperture Radar (DDInSAR). A total of seven Sentinel-1A SAR images acquired in 2015-2016 were used to estimate the accuracy of tide prediction model and Young's modulus of ice shelf. First, we compared the Ross Sea Height-based Tidal Inverse (Ross_Inv) model, which is a representative tide prediction model for the Antarctic Ross Sea, with the tide deformation of the ice shelf extracted from the DDInSAR image. The accuracy was analyzed as 3.86 cm in the east region of Ross Ice Shelf and it was confirmed that the inverse barometric pressure effect must be corrected in the tide model. However, in the east, it is confirmed that the tide model may be inaccurate because a large error occurs even after correction of the atmospheric effect. In addition, the Young's modulus of the ice was calculated on the basis of the one-dimensional elastic beam model showing the correlation between the width of the hinge zone where the tide strain occurs and the ice thickness. For this purpose, the grounding line is defined as the line where the displacement caused by the tide appears in the DDInSAR image, and the hinge line is defined as the line to have the local maximum/minimum deformation, and the hinge zone as the area between the two lines. According to the one-dimensional elastic beam model assuming a semi-infinite plane, the width of the hinge region is directly proportional to the 0.75 power of the ice thickness. The width of the hinge zone was measured in the area where the ground line and the hinge line were close to the straight line shown in DDInSAR. The linear regression analysis with the 0.75 power of BEDMAP2 ice thickness estimated the Young's modulus of 1.77±0.73 GPa in the east and west of the Ross Ice Shelf. In this way, more accurate Young's modulus can be estimated by accumulating Sentinel-1 images in the future.

A Study on Accelerated Photo-Degradation Test for Lifetime Estimation of Ink-jet Ink (잉크젯 잉크의 수명예측을 위한 광열화 가속시험법에 관한 연구)

  • Koo, Hyun-Jin;Cho, Hang-Won;Ji, Byung-Chul
    • Journal of Applied Reliability
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    • v.15 no.3
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    • pp.154-162
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    • 2015
  • We have performed accelerated photo-degradation test using a 10-Sun level high irradiance $Weather-Ometer^{(R)}$ (10-Sun Ci5000) in an attempt to study acceleration and correlation between accelerated and service conditions for ink-jet ink. The accelerated test was used to predict lifetimes of ink-jet ink through the calculation of scaling factor for intensity of irradiance and duration of usage combined with estimation of lifetime distribution and inverse power model as a life-stress model. The lifetimes and acceleration factors for foreign and domestic inks were compared with each other. The results showed that the failure mechanisms and life-stress models for ink-jet ink were different among the color of ink which means that we might be in need of further study by color of inks.

A hybrid model of regional path loss of wireless signals through the wall

  • Xi, Guangyong;Lin, Shizhen;Zou, Dongyao
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.16 no.9
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    • pp.3194-3210
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    • 2022
  • Wall obstruction is the main factor leading to the non-line of sight (NLoS) error of indoor localization based on received signal strength indicator (RSSI). Modeling and correcting the path loss of the signals through the wall will improve the accuracy of RSSI localization. Based on electromagnetic wave propagation theory, the reflection and transmission process of wireless signals propagation through the wall is analyzed. The path loss of signals through wall is deduced based on power loss and RSSI definition, and the theoretical model of path loss of signals through wall is proposed. In view of electromagnetic characteristic parameters of the theoretical model usually cannot be accurately obtained, the statistical model of NLoS error caused by the signals through the wall is presented based on the log-distance path loss model to solve the parameters. Combining the statistical model and theoretical model, a hybrid model of path loss of signals through wall is proposed. Based on the empirical values of electromagnetic characteristic parameters of the concrete wall, the effect of each electromagnetic characteristic parameters on path loss is analyzed, and the theoretical model of regional path loss of signals through the wall is established. The statistical model and hybrid model of regional path loss of signals through wall are established by RSSI observation experiments, respectively. The hybrid model can solve the problem of path loss when the material of wall is unknown. The results show that the hybrid model can better express the actual trend of the regional path loss and maintain the pass loss continuity of adjacent areas. The validity of the hybrid model is verified by inverse computation of the RSSI of the extended region, and the calculated RSSI is basically consistent with the measured RSSI. The hybrid model can be used to forecast regional path loss of signals through the wall.

An Accelerated Life Test of Thermoelectric Module for Water Purifier (정수기 적용 열전모듈의 가속수명시험)

  • Moon, Ji Seob;Lee, Sung Min;Jeong, Seon Yong;Kim, Myung Soo
    • Journal of Applied Reliability
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    • v.14 no.1
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    • pp.21-28
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    • 2014
  • This paper presents an accelerated life test to estimate the lifetime of thermoelectric module for home water purifier. Clamping force and thermal cycle are selected as accelerating variables through the technical review about failure mechanism. It is assumed that its lifetime follows weibull distribution. The relationship, acceleration factor, and BP life at design condition are estimated by analyzing the accelerated life test data.

Design of Multi-winding Inductor for Minimum Inductor Current Ripple Using Optimized Coupling Factor

  • Kang, Taewon;Suh, Yongsug
    • Proceedings of the KIPE Conference
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    • 2016.07a
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    • pp.231-232
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    • 2016
  • This paper investigates the design of multi-winding coupled inductor for minimum inductor current ripple. Based on the general circuit model of coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor of n-phase multi-winding coupled inductor which corresponds to a minimum inductor ripple current becomes -(1/n-1), i.e. a complete inverse coupling without leakage inductance, as the duty ratio of steady-state operating point approaches 1/n, 2/n, ${\cdots}$ or (n-1)/n. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the duty ratio of steady-state operating point approaches either zero or one. Therefore, coupled inductors having optimal coupling factor can minimize the ripple current of inductor and inductor size.

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Nonparametric Estimation for Ramp Stress Tests with Stress Bound under Intermittent Inspection (단속적 검사에서 스트레스한계를 가지는 램프스트레스시험을 위한 비모수적 추정)

  • Lee Nak-Young;Ahn Ung-Hwan
    • Journal of Korean Society for Quality Management
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    • v.32 no.4
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    • pp.208-219
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    • 2004
  • This paper considers a nonparametric estimation of lifetime distribution for ramp stress tests with stress bound under intermittent inspection. The test items are inspected only at specified time points an⊂1 so the collected observations are grouped data. Under the cumulative exposure model, two nonparametric estimation methods of estimating the lifetime distribution at use condition stress are proposed for the situation which the time transformation function relating stress to lifetime is a type of the inverse power law. Each of items is initially put on test under ramp stress and then survivors are put on test under constant stress, where all failures in the Inspection interval are assumed to occur at the midi)oint or the endpoint of that interval. Two proposed estimators of quantile from grouped data consisting of the number of items failed in each inspection interval are numerically compared with the maximum likelihood estimator(MLE) based on Weibull distribution.

Electrical Lifetime Estimation of a Relay by Accelerated Life Test (가속수명시험을 이용한 릴레이의 전기적 수명예측)

  • Kim, Jae-Jung;Chang, Seog-Weon;Son, Young-Kap
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.5
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    • pp.430-436
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    • 2008
  • This paper proposes a way to predict electrical lifetime of a relay using Accelerated Life Testings (ALTs). The relay of interest mounting on printed circuit boards is usually under an inrush current stress. The inrush current is generated and accelerated through controlling a lamp switching device in the ALT. We find that the dominant failure mechanism under high levels of inrush current would be contact welding in the contact surface of the relay and the contact welding process is accelerated according to increase in inrush current. The electrical lifetime model based on Inverse Power Law in term of inrush current is proposed, and parameters characterizing relay's lifetime distribution are statistically estimated using ALTA 6 PRO software.