• Title/Summary/Keyword: Allowable tolerance

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Investigation on Damage Tolerance of Thick Laminate for Aircraft Composite Structure (항공기 복합재 구조에 적용된 두꺼운 적층판의 손상 허용 기준 평가)

  • Park, Hyun-Bum;Kong, Chang-Duk;Shin, Chul-Jin
    • Composites Research
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    • v.25 no.4
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    • pp.105-109
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    • 2012
  • Recently, development of a small aircraft has been carried out for the BASA(Bilateral Aviation Safety Agreement) program in Korea. This aircraft adopted all composite structures for environmental friendly by low fuel consumption due to its lightness behavior. However the composite structure has disadvantage which is very weak against impact damages. Therefore, damage allowable design of aircraft structure must be performed considering compressive fracture strength. This point is very important for certification of composite structure aircraft. In this paper, it is performed the research on damage tolerance of thick laminate adopting aircraft structure. The damage tolerance of three different types of thick laminates such as no damage, open hole and impact damage is evaluated under compression loading.

A Study of Six Sigma and Total Error Allowable in Chematology Laboratory (6 시그마와 총 오차 허용범위의 개발에 대한 연구)

  • Chang, Sang-Wu;Kim, Nam-Yong;Choi, Ho-Sung;Kim, Yong-Whan;Chu, Kyung-Bok;Jung, Hae-Jin;Park, Byong-Ok
    • Korean Journal of Clinical Laboratory Science
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    • v.37 no.2
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    • pp.65-70
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    • 2005
  • Those specifications of the CLIA analytical tolerance limits are consistent with the performance goals in Six Sigma Quality Management. Six sigma analysis determines performance quality from bias and precision statistics. It also shows if the method meets the criteria for the six sigma performance. Performance standards calculates allowable total error from several different criteria. Six sigma means six standard deviations from the target value or mean value and about 3.4 failures per million opportunities for failure. Sigma Quality Level is an indicator of process centering and process variation total error allowable. Tolerance specification is replaced by a Total Error specification, which is a common form of a quality specification for a laboratory test. The CLIA criteria for acceptable performance in proficiency testing events are given in the form of an allowable total error, TEa. Thus there is a published list of TEa specifications for regulated analytes. In terms of TEa, Six Sigma Quality Management sets a precision goal of TEa/6 and an accuracy goal of 1.5 (TEa/6). This concept is based on the proficiency testing specification of target value +/-3s, TEa from reference intervals, biological variation, and peer group median mean surveys. We have found rules to calculate as a fraction of a reference interval and peer group median mean surveys. We studied to develop total error allowable from peer group survey results and CLIA 88 rules in US on 19 items TP, ALB, T.B, ALP, AST, ALT, CL, LD, K, Na, CRE, BUN, T.C, GLU, GGT, CA, phosphorus, UA, TG tests in chematology were follows. Sigma level versus TEa from peer group median mean CV of each item by group mean were assessed by process performance, fitting within six sigma tolerance limits were TP ($6.1{\delta}$/9.3%), ALB ($6.9{\delta}$/11.3%), T.B ($3.4{\delta}$/25.6%), ALP ($6.8{\delta}$/31.5%), AST ($4.5{\delta}$/16.8%), ALT ($1.6{\delta}$/19.3%), CL ($4.6{\delta}$/8.4%), LD ($11.5{\delta}$/20.07%), K ($2.5{\delta}$/0.39mmol/L), Na ($3.6{\delta}$/6.87mmol/L), CRE ($9.9{\delta}$/21.8%), BUN ($4.3{\delta}$/13.3%), UA ($5.9{\delta}$/11.5%), T.C ($2.2{\delta}$/10.7%), GLU ($4.8{\delta}$/10.2%), GGT ($7.5{\delta}$/27.3%), CA ($5.5{\delta}$/0.87mmol/L), IP ($8.5{\delta}$/13.17%), TG ($9.6{\delta}$/17.7%). Peer group survey median CV in Korean External Assessment greater than CLIA criteria were CL (8.45%/5%), BUN (13.3%/9%), CRE (21.8%/15%), T.B (25.6%/20%), and Na (6.87mmol/L/4mmol/L). Peer group survey median CV less than it were as TP (9.3%/10%), AST (16.8%/20%), ALT (19.3%/20%), K (0.39mmol/L/0.5mmol/L), UA (11.5%/17%), Ca (0.87mg/dL1mg/L), TG (17.7%/25%). TEa in 17 items were same one in 14 items with 82.35%. We found out the truth on increasing sigma level due to increased total error allowable, and were sure that the goal of setting total error allowable would affect the evaluation of sigma metrics in the process, if sustaining the same process.

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A Study on The Design of Prestressed Die for Spur Gear Forging (스퍼기어 단조용 예압된 금형의 설계에 관한 연구)

  • 허관도;여홍태;송요선
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.19-22
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    • 2003
  • In this study, the design of prestressed die for spur gear forging have been investigated. The stress concentration at notch of the die insert is very important in the design of die for the forging of spur gear such as non-axisymmetric geometry. In the previous study, the flexible tolerance method was used in order to search the optimal value of design variables considering the constrain conditions. In the design process, it was also involved the safety factor to the yield strength of each ring by considering allowable tensile or compressive hoop stress in each ring. Using this technique, the die deign for spur gear forging has been successfully performed without yielding of the die after shrink fitting and during forging.

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Performance Analysis for Passive Filter Considering Allowable Limits of Tolerance (오차의 허용범위를 고려한 수동형 필터의 특성 해석)

  • Kim, Jong-Gyeum;Kim, Il-Jung
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.1
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    • pp.38-43
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    • 2009
  • Reactors are connected with capacitors to passive filter circuits for reducing harmonics caused by power conversion application. This passive filter frequently gets out of order by voltage and current stress. Especially filter reactor has too much voltage harmonics components, its trouble rate is higher than capacitor. In this paper, we analyzed voltage and current of reactor and capacitor used for passive filter by simulation and measurement. If reactor has a tolerance on variation of reactance value, series resonance frequency is different from originally filter design frequency and parallel resonance can be generated at the close point of the former. Because filter absorbs harmonic component of non-linear load, much of harmonic voltage has been impacted on reactor.

Analysis of Specific Problems in Laser Scanning Optical System Design

  • Joo, Won-Don
    • Journal of the Optical Society of Korea
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    • v.15 no.1
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    • pp.22-29
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    • 2011
  • We analyze aberrations in an optical laser printer system in order to know how to determine an allowable non-uniformity of the movement of a light spot, how to determine allowed variation of spot sizes, and how to minimize the influence of these deviations on technological errors. In this paper, the correction and the tolerance of distortion are analyzed by using the concept of zonal and global distortions. The tolerance of field curvature is also obtained from Gaussian beam properties. In order to reduce the change of the entrance pupil position and to make a more compact laser printer system the minimum size of the rotator is exactly derived from the geometry with the introduction of the shift angle of the input beam.

An improved NC-code generation method for circular interpolation (새로운 원호보간법에 의한 공구경로의 생성)

  • Yang, Min-Yang;Shon, Tae-Young;Cho, Hyun-Deog
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.11
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    • pp.77-83
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    • 1997
  • This work is concerned with the algorithm of generating a new circular are interpolation. This research presents a new biarc curve fitting that is a circular interpolation method based on a triarc curve fitting. The triarc method, where a segment span is composed of three circular arcs, using maximum error estimation has the advantage of generating arc splines easily to a given tolerance. The new biarc method is called when the adjacent radii are the same in the same in the triarc method. In generating the machining data for various cam curves in CNC machining with the biarc method and the new biarc method, the latter accomp- lished faster NC-code generation, shorter NC-code block formation and machined the same cam profile more efficiently.

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Studying on Mobile backhaul Based on FTTH network (FTTH 인프라를 이용한 이동통신 기지국 백홀 제공방안 연구)

  • Kim, Geun-Young;Kim, Jin-Hee;Woo, Kyung-Il
    • 한국정보통신설비학회:학술대회논문집
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    • 2009.08a
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    • pp.78-80
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    • 2009
  • In this paper, we have described the advantages of fixed mobile convergence access network based on FTTH. Also, we have investigated the possibility of mobile backhaul based on FTTH network combined TOM over IP emulation and adaptive clock recovery technologies, and verified successful transport of both E1 TDM traffic and Clock through the packet based PON network. within the allowable tolerance.

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A study on the method for calculation the floor impact sound (바닥충격음 예측법에 관한 연구)

  • 이성호;정갑철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.184-190
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    • 2003
  • In this study, several methods for measuring floor impact sound were introduced. Among them, the simple methods (impedance method and diffuse index method) which can be easily applied to site works were investigated. Moreover, the comparison between the calculation results using diffuse index method and the experimental results measured in real apartment structures was conducted. Consequently, the modified diffuse index method, which can be practically used for predicting the performance of to the floor impact sound of apartment structures and can meet the allowable tolerance of Grade I (${\pm}$5㏈), was proposed.

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A Methodology to Determine Composite Material Allowables and Design Values Using Building Block Approach (빌딩블록 접근법을 이용한 복합재 재료 허용치 및 설계치 설정 방법)

  • Kim, Sung Joon;Lee, Seung-gyu;Hwang, In-hee
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.6
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    • pp.377-384
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    • 2022
  • In the design of composite aircraft structures, it is very important to set material allowables and design values, which take into account certification. And when determining the material allowable and design value of composite structures, the static strength, damage tolerance requirements, and environmental effects should be considered. The building block approach has been applied to the civil and military aviation industry for a long time and provides the principal certification methodology. This current certification methodology is based on extensive testing including coupon, element, sub-component, and full scale test. In this paper, some examples of composite allowable tests have been presented and the fundamental background and application methods of the building block approach have been presented.

A Study on Characteristic of Cogging Torque due to Assembly Tolerances of Magnet on Rotor and Evaluation of Noise and Vibration in Brushless DC Motor (BLDC 전동기에서 회전자 자석의 조립 공차에 따른 코깅토크 특성변화와 소음진동 불량 평가에 관한 연구)

  • Yun, Seung Ho;Ro, Seung Il;Kim, Hui Min;Park, Gwan Soo
    • Journal of the Korean Magnetics Society
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    • v.26 no.3
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    • pp.86-91
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    • 2016
  • The cogging torque of a brushless dc (BLDC) motor results from the interaction between permanent magnets and iron core, and it causes noise and induce vibrations. During a manufacturing process, assembly tolerances lead to the change of the electromagnetic structure of a BLDC motor where permanent magnets are not properly glued to the surface of rotor core. In this paper, the effect of magnet separation from the surface of rotor core on the cogging torque is investigated due to assembly tolerance. The relationship with key design parameters is considered such as separation between magnets and rotor core, the number of magnets having separation, as well as the several types of arrangements among neighboring magnets. Finite element method (FEM) has been used to analyze a BLDC motor, and the allowable assembly tolerance is proposed to prevent generating noise and vibrations. Within proposed assembly tolerance, it is concluded that the cogging torque of a BLDC motor is decreased, and hence noise and vibrations.