• Title/Summary/Keyword: backing

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Phonological Error Patterns: Clinical Aspects on Coronal Feature (음운 오류 패턴: 설정성 자질의 임상적 고찰)

  • Kim, Min-Jung;Lee, Sung-Eun
    • Phonetics and Speech Sciences
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    • v.2 no.4
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    • pp.239-244
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    • 2010
  • The purpose of this study is to investigate two phonological error patterns on coronal feature of children with functional articulation disorders and to compare them with those of general children. We tested 120 children with functional articulation disorders and 100 general children from 2~4 years of age with 'Assessment of Phonology & Articulation for Chidren(APAC)'. The results were as follows: (1) 37 disordered children substituted [+coronal] consonants for [-coronal] consonants (fronting of velars) and 9 disordered children substituted [-coronal] consonants for [+coronal] consonants (backing to velars). (2) Theses two phonological patterns were affected by the articulatory place of following phoneme. (3) The fronting pattern of children with articulation disorders was similar with that of general children, but their backing pattern was different with that of general children. These results show the clinical usefulness of coronal feature in phonological pattern analysis, the need of articulatory assessment with various phonetic context, and the importance of error contexts in clinical judgment.

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A Study on PZT-5A Probe for Nondestructive Inspection (비파괴검사를 위한 PZT-5A 탐촉자에 관한 연구)

  • 황현석
    • Electrical & Electronic Materials
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    • v.10 no.2
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    • pp.119-125
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    • 1997
  • In this study, piezoelectric transducers were designed and manufactured using PZT-5A which had relatively high electromechanical coefficient, nondestructive testing system was developed which was able to inspect automatically using stepping motors, PC-Lab, and PC-Scope. The optimum design conditions for NDT were presented and verified comparing PZT-5A probes with comercial probes. It was proved by simulation and experiments that Epoxy is a good material as matching and backing layers. The envelope was reduced 60% with matching layer and 76% with matching and backing layer. NDT was successfully carried out for aluminum test pieces. Distance error of PZT-5A probe was 2.8%.

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Effect of Disk Material on the Performance of Cermet Tipped Circular Saw (서멧팁 은납형 둥근톱의 성능에 미치는 기판의 영향)

  • Lee Jae-Woo
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.350-353
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    • 2005
  • It is a feature of primary importance for a backing material for circular saw blades having teeth which are tipped with cermet, that the steel has not a too high hardenability in order that the backing material shall not be completely hardened through brazing, welding or grinding, etc. in connection with the finishing operation in the manufacturing of circular saw blade. It is believed that V-(2Mo+W) added steel from this point of view had best conditions. Using V-(2Mo+W) added backing steel, the tool failure can be effectively prevented due to superior damping performance.

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NEW RESULTS CONCERNING THE INFLUENCE OF HEAT TINGS DURING WELDING ON THE CORROSION RESISTANCE OF STAINLESS STEELS

  • Wohlfahrt, H.;Pries, H.;Saggau, R.
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.29-37
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    • 2002
  • High alloyed stainless steels stand out for a high corrosion resistance due to a protective passive layer which is formed when the content of chromium exceeds 13%. When welding these steels, heat tints arise in the area of the weldment. They may occur from flint yellow to intensive blue in the spectrum depending on the applied welding process and the quality of the backing gas used. Due to their structures, they partly drastically reduce the corrosion resistance of stainless steels so that they may lead to damages of the technical application of welded components. In the following the pitting resistance by different backing gases and the chemical composition of the stainless steel itself are described.

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A Shape Control of Welded Joints to Improve Fatigue Strength (피로강도 향상을 위한 용접이음부의 형상제어에 관한 연구)

  • Kang, Chang Ib;Kook, Seung Kyu;Lee, Dong Uk
    • Journal of Korean Society of Steel Construction
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    • v.16 no.4 s.71
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    • pp.479-492
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    • 2004
  • When U-ribs of steel deck plates are connected at the field, overhead welding should be done with backing strips. Misalignments may occur and lead to eccentric moments as well as high stress concentrations at welded joints. In this study, stress analyses and fatigue tests were carried out. Stress analyses for U-ribs' welded joints with backing strips were performed with different misalignments, root shapes, root gaps, and backing strip sizes. From the stress analyses, the stress concentration factors increased with increasing misalignments and root gaps. With the fixed misalignments and root gaps, the stress concentration factors obtained in the case of the semi-circle root shape were lower than those in the case of the right-angle root shape. It was verified that backing strip sizes have little influence on stress concentration factors. The fatigue tests for U-ribs' welded joints with backing strips indicated that increased misalignments shorten fatigue life drastically and cracks usually initiate at the root of the base metal and are propagated to the weld bead surface. Based on the results of the stress analyses, root-shape control methods were developed to mitigate stress concentration by changing welding condition control, radius curvature, and flank angle.

Characterization of Component Materials of the Ultrasonic Transducer (초음파 탐촉자 구성 재료의 특성 연구)

  • Kim, B.G.;Park, Y.K.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.9 no.1
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    • pp.69-76
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    • 1989
  • Piezoelectric elements, backing and shoe material are the important components of the ultrasonic transducer. In this study, characteristic constants in the domestic and the foreign PZT ceramic elements are investigated, The acoustic properties of the domestic and the foreign backing and shoes are characterized. The effects of components characteristics, the kinds of the piezoelectric elements and the thickness of the wear plates are investigated for the manufactured normal beam ultrasonic transducers.

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Impedance Tube Measurements of Sound Absorbing Materials: Sensitivity Analysis on Backing Conditions (임피던스 관을 이용한 흡음재의 특성 임피던스 측정: 배후조건에 따른 민감도 분석)

  • 이종화;이정권;박봉현;김병훈
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.888-891
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    • 2001
  • Effects of backing conditions on the impedance tube measurement are investigated experimentally, by using several pairs of generally employed end conditions. The results show that the measured values are similar for most of pairs, except the case of using an open pipe condition. In addition, the random error is investigated in the viewpoint of the variation of test conditions. The multi-termination method is suggested for minimizing such a random error.

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Failure Mode Analysis and Friction Material Development of the KTX tread Brake (고속철도 제륜자 결함분석 및 제륜자 개발)

  • Baek, Jong-Kil;Goo, Byeong-Choon;Koo, Jeong-Seo
    • Journal of the Korean Society for Railway
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    • v.14 no.2
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    • pp.109-115
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    • 2011
  • The shoe brake of the KTX is used in low speed when the electric brake is not effective. The main purpose of the shoe brake is to stop the train to a desired stop point at the station. Lots of defects have been encountered in the shoe brake unit since the KTX started its operation. To improve the reliability of shoe brake unit of the KTX power car, first of all, failure modes of the KTX shoe brake unit were analyzed. Main failure modes are cracks in the shoe friction material and fracture in the welded joints of the shoe backing steel structure. Several methods to remove the defects of the shoe brake unit were proposed and on-board tests were carried out: Increase of the strength of the shoe key and shoe cam, which decreased a little the occurrence of cracks in the shoe friction material; Redesign of the shoe backing steel structure, which eliminated the occurrence of the cracks in the backing plate but could not solve completely the crack problem in the shoe friction material; Development of a new friction material, which with redesign of the shoe backing steel structure could solve satisfactorily the crack problem in the shoe friction material.

Multi-Termination Technique for the Measurement of Characteristic Impedance and Propagation Constant of Sound Absorbing Materials Using an Impedance Tube

  • Lee, Jong-Hwa;Ih, Jeong-Guon
    • The Journal of the Acoustical Society of Korea
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    • v.25 no.2E
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    • pp.79-84
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    • 2006
  • Acoustic characteristics of a sound absorbing material can be identified, if the characteristic impedance and propagation constants are known, which have generally been determined experimentally. One easy method determining these two essential parameters is to measure the one dimensional wave characteristics in the impedance tube. In th udy, the effects of backing conditions on the impedance tube measurement have been examined using several pairs of generally used end conditions. The results showed that the measured values are similar for most pairs of end conditions: however, it was observed that the measured characteristic impedance for different thickness did not agree well for some pairs. In this work, the multi termination method, using three or more known backing con ns, was suggested to reduce such random errors, which are mostly caused by the test procedure. Employing three terminations as a set, comprised of a rigid end, an end with porous material, and an end with a backing cavity, it was demonstrated that improved measured results could be obtained for an open cell PU foam varying widely with three different thicknesses.

Absorption Characteristics of Perforated Environment Friendly Sound Absorbing Board using Hwangto (황토를 이용한 친환경 유공 흡음보드의 흡음특성)

  • Kim, Sun-Woo;Park, Hyeon Ku
    • KIEAE Journal
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    • v.11 no.1
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    • pp.3-8
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    • 2011
  • Sound absorbing materials used for lightweight panels and interior material are mainly made of fibroid material such as glass wool or rock wool. However these fiber type sound absorbing materials have some problems such that sound absorption could be decreased as time goes by because of durability. In addition, dust scattering from fiber type material can cause another problem in health. In this point of view, this study aims to develop environment friendly sound absorbing material using Hwangto(so called loess or yellow soil), a traditional housing material. Hwangto is natural housing material in Korea and generally known for improving indoor air quality. Hwangto panel is made to construct on the floor, wall and ceiling, and expected that there is not enough absorption. Present study tried to develop environment friendly sound absorbing material that has high sound absorption performance with good environment performance in terms of air quality. Pore rate was designed to maximize the absorption in the specific frequency bands, and two kinds of backing space were applied in order to see the effect of backing space. As a result peak frequency that has maximum absorption is going high as the pore rate is increased. The backing space provides more absorption and makes the peak frequency down to low.