• Title/Summary/Keyword: maximum lifetime

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A Simulated Study of Silicon Solar Cell Power Output as a Function of Minority-Carrier Recombination Lifetime and Substrate Thickness

  • Choe, Kwang Su
    • Korean Journal of Materials Research
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    • v.25 no.9
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    • pp.487-491
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    • 2015
  • In photovoltaic power generation where minority carrier generation via light absorption is competing against minority carrier recombination, the substrate thickness and material quality are interdependent, and appropriate combination of the two variables is important in obtaining the maximum output power generation. Medici, a two-dimensional semiconductor device simulation tool, is used to investigate the interdependency in relation to the maximum power output in front-lit Si solar cells. Qualitatively, the results indicate that a high quality substrate must be thick and that a low quality substrate must be thin in order to achieve the maximum power generation in the respective materials. The dividing point is $70{\mu}m/5{\times}10^{-6}sec$. That is, for materials with a minority carrier recombination lifetime longer than $5{\times}10^{-6}sec$, the substrate must be thicker than $70{\mu}m$, while for materials with a lifetime shorter than $5{\times}10^{-6}sec$, the substrate must be thinner than $70{\mu}m$. In substrate fabrication, the thinner the wafer, the lower the cost of material, but the higher the cost of wafer fabrication. Thus, the optimum thickness/lifetime combinations are defined in this study along with the substrate cost considerations as part of the factors to be considered in material selection.

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
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    • v.37 no.1_2
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    • pp.105-121
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    • 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.

Traffic Load & Lifetime Deviation based Power-aware Routing Protocol for MANET (MANET에서 트래픽 부하와 노드 수명 편차에 기반한 power-aware 라우팅 프로토콜)

  • Kim, Dong-Hyun;Ha, Rhan
    • Journal of KIISE:Information Networking
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    • v.33 no.5
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    • pp.395-406
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    • 2006
  • In ad hoc networks, the limited battery capacity of nodes affects a lifetime of network Recently, a large variety of power-aware routing protocols have been proposed to improve an energy efficiency of ad hoc networks. Existing power-aware routing protocols basically consider the residual battery capacity and transmission power of nodes in route discovery process. This paper proposes a new power-aware routing protocol, TDPR(Traffic load & lifetime Deviation based Power-aware Routing protocol), that does not only consider residual battery capacity and transmission power, but also the traffic load of nodes and deviation among the lifetimes of nodes. It helps to extend the entire lifetime of network and to achieve load balancing. Simulations using ns-2[14] show the performance of the proposed routing protocol in terms of the load balancing of the entire network, the consumed energy capacity of nodes, and an path's reliability TDPR has maximum 72% dead nodes less than AODV[4], and maximum 58% dead nodes less than PSR[9]. And TDPR consumes residual energy capacity maximum 29% less than AODV, maximum 15% less than PSR. Error messages are sent maximum 38% less than PSR, and maximum 41% less than AODV.

Extension of Wireless Sensor Network Lifetime with Variable Sensing Range Using Genetic Algorithm (유전자알고리즘을 이용한 가변감지범위를 갖는 무선센서네트워크의 수명연장)

  • Song, Bong-Gi;Woo, Chong-Ho
    • Journal of Korea Multimedia Society
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    • v.12 no.5
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    • pp.728-736
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    • 2009
  • We propose a method using the genetic algorithm to solve the maximum set cover problem. It is needed for scheduling the power of sensor nodes in extending the lifetime of the wireless sensor network with variable sensing range. The existing Greedy Heuristic method calculates the power scheduling of sensor nodes repeatedly in the process of operation, and so the communication traffic of sensor nodes is increased. The proposed method reduces the amount of communication traffic of sensor nodes, and so the energies of nodes are saved, and the lifetime of network can be extended. The effectiveness of this method was verified through computer simulation, and considering the energy losses of communication operations about 10% in the network lifetime is improved.

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Maximum Lifetime Geocast Considering Link Error Rates in Ad-Hoc Networks (Ad-hoc 네트워크에서 최대 네트워크 수명과 링크 에러율을 고려한 지오캐스트)

  • Lee, Ju-Young
    • Journal of the Korea Society for Simulation
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    • v.15 no.3
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    • pp.69-77
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    • 2006
  • Geocasting is a form of communication that transmits messages to all nodes within a given geographical region(i.e., the geocasting region). Most of conventional onery aware protocols were based on shortest-hop routing that is, they minimized the cost in terms of the distance and total transmission energy not considering both the residual energy at each node and the link error ratio when selecting the routes for communication. In this paper we propose a MLRG(Maximum Lifetime Reliable Geocast) protocol for energy-efficient and reliable geocasting in Ad-hoc networks. The proposed MLRG, a position-based and routing-based geocasting algorithm, maximizes the network lifetime using newly defined cost function and selecting the energy balanced routes on the basis of each node's residual energy, and provides a reliable communication considering the link error ratio.

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Effect of Ganglioside $G_{M3}$ on the Erythrocyte Glucose Transporter (GLUT1): Conformational Changes Measured by Steady-State and Time-Resolved Fluorescence Spectroscopy

  • Yoon, Hae-Jung;Lee, Min-Yung;Jhon, GiI-Ja
    • BMB Reports
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    • v.30 no.4
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    • pp.240-245
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    • 1997
  • Interactions between ganglioside $G_{M3}$ and glucose transporter, GLUT1 were studied by measuring the effect of $G_{M3}$ on steady-state and time-resolved fluorescence of purified GLUT1 in synthetic lipids and on the 3-O-methylglucose uptake by human erythrocytes. The intrinsic tryptophan fluorescence showed a GLUT 1 emission maximum of 335 nm, and increased in the presence of $G_{M3}$ by 12% without shifting the emission maximum, The fluorescence lifetimes of intrinsic tryptophan on GLUT1 consisted of a long component of 7.8 ns and a short component of 2,3 ns and $G_{M3}$ increased both lifetime components. Lifetime components were quenched by acrylamide and KI. Acrylarnide-mduced quenching of long-lifetime components was partly recovered by $G_{M3}$ However. KI-induccd quenching of short- and long-lifetime components was not rescued by $G_{M3}$. The anisotropy of 1.6-diphenyl-1.3.5-hexatriene (DPH)-probed dimyristoylphosphatidylcholine (DMPC) model membrane was also increased with $G_{M3}$ incorporation, The transport rate of 3-O-methylglucose increased by 20% with $G_{M3}$ incorporation on the erythrocytes, Therefore, $G_{M3}$ altered the environment of lipid membrane and induced the conformational change of GLUT1.

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Study on the Optimum Design of the Insert Ring and Shrunk Ring of the Cold Forging Die for an Automotive Wheel Nut (자동차 휠 너트용 냉간단조 금형에서 인서트링과 보강링의 최적 설계에 관한 연구)

  • Lee, K.S.;Kim, G.Y;Ahn, Y.S.
    • Transactions of Materials Processing
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    • v.27 no.3
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    • pp.165-170
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    • 2018
  • In order to increase the lifetimes of cold forging dies, insert rings are generally used. In this study, an insert ring and shrunk ring of the flange upsetting die were designed for the cold forging of an automotive wheel nut. The Stress distribution occurring in the die during forging was simulated using a commercial finite element analyzing program. The effects of the fitting interference and inclined angle of the insert ring on the compressive stress of the die inside were also investigated. The simulated data were compared with the real lifetimes of the forging dies. The maximum compressive stress acting on the edge of a forging die should have the most influence on die lifetime, an idea which could help develop the die design with the longest lifetime. The design of the most optimal forging die with the longest lifetime is made possible by analyzing the maximum inner pressure and principal stress between the shrunk ring and insert ring.

Multistress Life Models of Epoxy Encapsulated Magnet wire under High Frequency Pulsating Voltage

  • Grzybowski, S.;Feilat, E.A.;Knight, P.
    • KIEE International Transactions on Electrophysics and Applications
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    • v.3C no.1
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    • pp.1-4
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    • 2003
  • This paper presents an attempt to develop probabilistic multistress life models to evaluate the lifetime characteristics of epoxy-encapsulated magnet wire with heavy build polyurethane enamel. A set of accelerated life tests were conducted over a wide range of pulsating voltages, temperatures, and frequencies. Samples of fine gauge twisted pairs of the encapsulated magnet wire were tested us-ing a pulse endurance dielectric test system. An electrical-thermal lifetime function was combined with the Weibull distribution of lifetimes. The parameters of the combined Weibull-electrical-thermal model were estimated using maximum likelihood estimation. Likewise, a generalized electrical-thermal-frequency life model was also developed. The parameters of this new model were estimated using multiple linear regression technique. It was found in this paper that lifetime estimates of the two proposed probabilistic multistress life models are good enough. This suggests the suitability of using the general electrical-thermal-frequency model to estimate the lifetime of the encapsulated magnet wire over a wide range of voltages, temperatures and pulsating frequencies.

Simulated Study on the Effects of Substrate Thickness and Minority-Carrier Lifetime in Back Contact and Back Junction Si Solar Cells

  • Choe, Kwang Su
    • Korean Journal of Materials Research
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    • v.27 no.2
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    • pp.107-112
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    • 2017
  • The BCBJ (Back Contact and Back Junction) or back-lit solar cell design eliminates shading loss by placing the pn junction and metal electrode contacts all on one side that faces away from the sun. However, as the electron-hole generation sites now are located very far from the pn junction, loss by minority-carrier recombination can be a significant issue. Utilizing Medici, a 2-dimensional semiconductor device simulation tool, the interdependency between the substrate thickness and the minority-carrier recombination lifetime was studied in terms of how these factors affect the solar cell power output. Qualitatively speaking, the results indicate that a very high quality substrate with a long recombination lifetime is needed to maintain the maximum power generation. The quantitative value of the recombination lifetime of minority-carriers, i.e., electrons in p-type substrates, required in the BCBJ cell is about one order of magnitude longer than that in the front-lit cell, i.e., $5{\times}10^{-4}sec$ vs. $5{\times}10^{-5}sec$. Regardless of substrate thickness up to $150{\mu}m$, the power output in the BCBJ cell stays at nearly the maximum value of about $1.8{\times}10^{-2}W{\cdot}cm^{-2}$, or $18mW{\cdot}cm^{-2}$, as long as the recombination lifetime is $5{\times}10^{-4}s$ or longer. The output power, however, declines steeply to as low as $10mW{\cdot}cm^{-2}$ when the recombination lifetime becomes significantly shorter than $5{\times}10^{-4}sec$. Substrate thinning is found to be not as effective as in the front-lit case in stemming the decline in the output power. In view of these results, for BCBJ applications, the substrate needs to be only mono-crystalline Si of very high quality. This bars the use of poly-crystalline Si, which is gaining wider acceptance in standard front-lit solar cells.

The Stockpile Reliability of Propelling Charge for Performance and Storage Safety using Stochastic Process (확률과정론을 이용한 추진장약의 성능과 저장안전성에 관한 저장신뢰성평가)

  • Park, Sung-Ho;Kim, Jae-Hoon
    • Journal of Korean Society for Quality Management
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    • v.41 no.1
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    • pp.135-148
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    • 2013
  • Purpose: This paper presents a method to evaluate the stockpile reliability of propelling charge for performance and storage safety with storage time. Methods: We consider a performance failure level is the amount of muzzle velocity drop which is the maximum allowed standard deviation multiplied by 6. The lifetime for performance is estimated by non-linear regression analysis. The state failure level is assumed that the content of stabilizer is below 0.2%. Because the degradation of stabilizer with storage time has both distribution of state and distribution of lifetime, it must be evaluated by stochastic process method such as gamma process. Results: It is estimated that the lifetime for performance is 59 years. The state distribution at each storage time can be shown from probability density function of degradation. It is estimated that the average lifetime as $B_{50}$ life is 33 years from cumulative failure distribution function curve. Conclusion: The lifetime for storage safety is shorter than for performance and we must consider both the lifetime for storage safety and the lifetime performance because of variation of degradation rate.