• Title/Summary/Keyword: Failed

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Failure Analysis of the Carburized Engine Parts by Microstructural Observation (침탄처리된 엔진 부품의 미세조직학적 파손원인 분석)

  • Sohn, Kyong-Suk;Lee, Sang-Kee;Chung, In-Sang
    • Journal of the Korean Society for Heat Treatment
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    • v.18 no.2
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    • pp.83-90
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    • 2005
  • Failure cause of the fractured engine parts was analyzed by microstructural observation. These parts were failed far earlier than the expected service life. By the stereoscope and SEM examinations of the fractured surface, the fracture modes have been identified as wear and fatigue failure. From the observation of microstructure and microhardness measurements of the failed gears, the probable cause for failures are internal oxidation during using and retained austenite and carbide networks due to heat-treatment, respectively. These defected structures at near surface contributed to the wear and fatigue failure.

Bayes Estimation of Reliability in the Strength-Stress Models

  • Yum, Joon-Keun;Kim, Jae-Joo;Cho, Sin-Sup;Park, Hong-Nai
    • Journal of Korean Society for Quality Management
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    • v.22 no.2
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    • pp.69-78
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    • 1994
  • We obtain the Bayes estimator(BE), the minimum variance unbiased estimator(MVUE) and maximun likelihood estimator(MLE) of the reliability when the distribution of the stress and the strength are Weibull with known shape parameters. The experiment is terminated before all of the items on the test have failed and the failed items are partially replaced. Performance of the three estimators for moderate size samples are compared through Monte Carlo simulation.

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Estimation of Smart Election System data

  • Park, Hyun-Sook;Hong, You-Sik
    • International journal of advanced smart convergence
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    • v.7 no.2
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    • pp.67-72
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    • 2018
  • On the internal based search, the big data inference, which is failed in the president's election in the United States of America in 2016, is failed, because the prediction method is used on the base of the searching numerical value of a candidate for the presidency. Also the Flu Trend service is opened by the Google in 2008. But the Google was embarrassed for the fame's failure for the killing flu prediction system in 2011 and the prediction of presidential election in 2016. In this paper, using the virtual vote algorithm for virtual election and data mining method, the election prediction algorithm is proposed and unpacked. And also the WEKA DB is unpacked. Especially in this paper, using the K means algorithm and XEDOS tools, the prediction of election results is unpacked efficiently. Also using the analysis of the WEKA DB, the smart election prediction system is proposed in this paper.

Vitamin D², Thyroxine, 및 Calcium gluconate가 백서악하선적출로 인한 혈중 Calcium농도변화에 미치는 영향

  • Cheong, Dong-Kyun;Park, No-Hee;Kim, Joong-KI
    • The Journal of the Korean dental association
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    • v.12 no.12
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    • pp.919-923
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    • 1974
  • Serum calcium level was decreased by submaxillary gland removal in rate. To investigate the mechanisms involved in the above change, the authors examined the effects of thyroxine, vitamin D₂, and calcium gluconate, which influence the metabolisms of calcium and submaxillary gland, on the serum calcium level of the intact and submaxillary gland removal rats. The results were as follows: 1) Serum calcium level decreased by submaxillary gland removal. 2) Vitamin D₂, increased the serum calcium level significantly. 3) Thyroxine falied to recover the decreased serum calcium level induced by submaxillary gland removal to the control level. 4) In submaxillary gland removal rats, vitamin D₂ failed to increase the serum calcium level. 5) In thyroxine administered rats for 55 days, of which submaxillary glands were removed, vitamin D₂ failed to increase the serum calcium level. 6) The serum calcium level in intact rats was increased slightly, but increased significantly in submaxillary gland removal rats shortly after intravenous injection of calcium gluconate.

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An Efficient Foot-Force Distribution Algorithm for Straight-Line Walking of Quadruped Robots with a Failed Leg (고장 난 다리가 있는 사족 보행 로봇의 평탄 직선보행을 위한 효율적인 다리 힘 배분 알고리즘)

  • Yang, Jung-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.5
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    • pp.896-901
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    • 2008
  • This paper addresses the foot force distribution problem for quadruped robots with a failed leg. The quadruped robot has fault-tolerant straight-line gaits with one leg in locked-joint failure, and has discontinuous motion with respect to the robot body. The proposed method is operated in two folds. When the robot body stands still, we use the feature that there are always three supporting legs, and by incorporating the theory of zero-interaction force, we calculate the foot forces analytically without resort to any optimization technique. When the robot body moves, the conventional pseudo-inverse algorithm is applied to obtain the foot forces for supporting legs. Simulation results show the validity of the proposed scheme.

The Case Study of High Strength Bolt Cadmium Embrittlement Failure (고강도 볼트 카드늄 취성파괴 사례연구)

  • Yoon, Young-In;Park, Chan-Wook;Sohn, Kyung-Suk
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.244-249
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    • 2008
  • It happened a failure on special bolt which supported main landing gear actuator up-lock rod of 00 aircraft. Fracture was occurred at end of center drilled hole and thread machined on bolt. Metallographic, fractographic, and other characteristics of embrittlement analysis and experiments carried out on the failed bolt to find out the reason. Bolt surface was cadmium electroplated(EP) to give lubrication and provide excellent corrosion resistance. Resultly, Bolt was failed due to cadmium embrittlement occurred during baking treatment as well as center drilled hole. for the failure that are relevant to failure analysis and prevention. For their successful functional application, cadmium EP bolts require proper and adequate baking treatment after electroplating, and is complete with no center drilled hole

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Estimation of Freund Model for System Level Life Testing Using Component Life Data (체계수명시험에서 얻어진 부품의 수명자료를 이용한 Freund 모형의 추정)

  • 홍연웅
    • Journal of Korean Society for Quality Management
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    • v.26 no.2
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    • pp.27-38
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    • 1998
  • Consider a life testing experiment in which multiple two-component shared parallel systems are put on test, and the test is terminated at a specified number of system failures. The bivariate data obtained from such a system-level life testing can be classified into three classes: 1) the case of failed two components with known failure times, 2) the case of censored two components, and 3) the case of one censored component and the other failed component of which the failure time might be known or unknown. Under this censoring scheme and the assumption of Freund's bivariate exponential life distribution, the maximum likelihood estimators are obtained. Results of comparative studies based on Monte Carlo simulation are presented.

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Premature Failure of Deep Grooved Ball Bearing for Automobiles : Part 2 - Critical Dent Size (자동차용 깊은홈 볼베어링의 조기파손 : 2보 - 임계압흔의 크기)

  • Hyun Joons;Park Tae Jo
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2003.11a
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    • pp.395-401
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    • 2003
  • In this paper, the dent printing phenomena and critical dent size which lead to premature failure of deep grooved ball bearing for automobiles are presented. The results of newly assembled test bearings showed that the ball dent size strongly affect the bearing life and inner ring raceways were the major failed parts in spite of using the dented balls. The dent printing phenomena are a root cause of premature failure, which was not reported until now. And there exist the critical ball dent size for given rolling bearings and operating conditions. So, the initial condition of tribologically mating parts should be treated as important as the failed body itself.

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Mechanical Properties Anisotropy of Plain Weave Glass Fabric Reinforced Epoxy Resin Laminates (평직유리섬유강화 에폭시 적층판의 기계적 특성 이방성)

  • Kim, Yon-Jig
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.3
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    • pp.15-21
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    • 2009
  • The anisotropic mechanical properties were measured for the three orthogonal orientations of plain weave glass fabric reinforced epoxy resin laminate. In tensile and flexural tests, axial and edge type specimens failed by pull-out of warp and fill yarns, respectively. In contrast, the thickness type specimens failed by adhesive failure process. Longitudinal cracking occurred in several of the edge type specimens during tensile test. That cracking caused pop-in in the stress-strain curve. Defects induced by improper coupon machining caused that cracking.

THE STUDY ON LONGEVITY OF AMALGAM AND COMPOSITE RESIN (Amalgam과 composite resin 수복물의 수명에 관한 연구)

  • Um, Chung-Moon;Kim, Seung-Soo;Bae, Kwang-Shik
    • Restorative Dentistry and Endodontics
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    • v.18 no.2
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    • pp.501-506
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    • 1993
  • The purpose of this study was to observe the longevity of amalgam and composite resin fillings in Korea. The number of placement of restorations was 760 amalgams and 415 composite resins. The amalgam restorations inserted because of primary caries were 61 % and replacement of amalgam restorations were 39%, and composite restorations inserted because of primary caries were 62 % and replacement of composite restorations were 38 %. The median longevity of failed amalgam restorations was 3 years and the madian longevity of failed composite restorations was 2 years. The main reason of replacement of amalgam and composite resin restorations was secondary caries.

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