• Title/Summary/Keyword: 피로 한도

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Strength evaluation of rear axle housing (후륜차축(8ton)의 강도평가)

  • 문상열;한응교;최만용
    • Journal of the korean Society of Automotive Engineers
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    • v.5 no.1
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    • pp.17-23
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    • 1983
  • 현재 생산되고 있는 8 ton 차축(후료)의 강도를 평가하기 위해 strain gauge에 의한 능력측정과 이 제품의 신뢰성 향상을 위한 피로 시험기에 의한 시험 및 특히 용접부분의 결함을 검출하기 위한 비파괴검사법의 적용 등, 제품에 대한 품질보증을 위한 일련의 시험을 한 결과를 보고하 고자 한다.

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Fatigue Crack Initiation and Propagation at Notches (노치 에서의 피로 균열 발생 과 전파 에 관한 연구)

  • 이강용;이택성
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.2
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    • pp.141-144
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    • 1984
  • The fatigue limits of crack initiation and propagation on the edge elliptical notched semi-infinite plate under completely reversed fatigue stress are determined theoretically. Assuming that the crack initiation and propagation occur when stress intensity factors of notched plate reach the critical values obtained from critical micro-crack length under plain fatigue limit loading and the threshold stress intensity factory, respectively, the fatigue limits of crack initiation and propagation are obtained. The induced theoretical fatigue limit of crack initiation is expressed in terms of plain fatigue limit, critical micro-crack length and notch shape. The one of crack propagation is in terms of threshold stress intensity factor, plain fatigue limit and notch shape. These theoretical results are showed to be in good agreement of Frost's experimental data.

An Adaptive Proximity Route Selection Scheme in DHT-Based Peer-to-Peer Systems (DHT기반 P2P시스템을 위한 적응적 근접 경로 선택 기법)

  • 송지영;박성용
    • Proceedings of the Korean Information Science Society Conference
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    • 2004.10c
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    • pp.187-189
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    • 2004
  • 피어-투-피어 시스템에서는 한 홉(hop) 떨어진 두 피어간의 네트워크 상 거리는, 이들 피어들이 서로 다른 대륙간 네트워크에 존재할 수도 있기 때문에 매우 클 수 있다. 그러나 검색 질의 메시지를 전달할 다음 피어를 선택하는 기존의 방법은 네트워크의 근접성을 고려하지 않고, 단순히 목적 피어까지의 홉 수를 최대로 줄이는 피어를 선택한다. 따라서 네트워크의 근접성을 고려하여 동적으로 다음 라우팅 피어를 선택하는 새로운 기법이 필요하다. 본 논문에서는 대표적 DHT 방식 시스템인 Chord를 중심으로, 검색 시간을 향상시키기 위한 적응적 근접 경로 선택 기법을 제시한다. 본 기법에서는 동적인 P2P 환경에 적응하기 위해서 지수적 최근-가중치 평균을 통해 예측된 지연시간을 바탕으로 쿼리를 전달할 다음 피어를 선택한다.

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A fracture mechanics evaluation on the fatigue crack propagation at spot welded aluminum joint in passenger car body (스폿용접된 자동차 차체용 알루미늄 박판의 피로균열진전의 파괴역학적 평가)

  • 박인덕;남기우;강석봉
    • Journal of Ocean Engineering and Technology
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    • v.11 no.3
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    • pp.20-28
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    • 1997
  • The fatigue crack propagation properties and fatigue life of two kinds of Al body panel for automobile were examined experimentally by using the plate specimen and the single spot welding specimen. The fatigue limit of spot welding specimens was lower than that of a plate specimen. The fatigue limit was similar in two kinds of spot welding specimen. The shape and size of crack propagation were observed and measured on beach mark of fracture surface. The crack propagation of surface crack specimen showed almost same tendency to that of a thick plate as almost semi-elliptical. In spot welding specimen, the fatigue crack occurred in inside surface of nugget area was almost semi-elliptical. The crack growth rate can be explained using equation of stress intensity factors.

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Anti-inflammatory Effect of Geumeunwha-san Water Extract on LPS-induced Raw 264.7 Cells (금은화산(金銀花散)의 LPS로 유도된 Raw 264.7 세포에서의 항염증 효과)

  • Kim, Yeon-Soo;Kim, Su-Jin;Jee, Seon-Young;Hwangbo, Min
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.34 no.3
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    • pp.1-12
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    • 2021
  • Objectives : The purpose of this study is to investigate the anti-inflammatory effect of Geumeunwha-san(GEHS) water extract in vitro. Methods : To evaluate the anti-inflammatory effect of GEHS, Raw 264.7 cells were pretreated with 10-300㎍/㎖ of GEHS for 1hr, and then exposed to 1㎍/㎖ of LPS. MTT assay was used to detect the cell viability. Productions of pro-inflammatory cytokines and NO were measured in culture media. By using immunoblot analysis, protein levels of iNOS and NF-𝜅B were determined. Results : In vitro study, cell viability assay on GEHS treatment of 10-300㎍/㎖ has no cytotoxicity in Raw 264.7 cells. Pretreated 100, 300㎍/㎖ of GEHS had significantly inhibited LPS-induced NO production. And also pretreatment of 100, 300㎍/㎖ GEHS had significantly decreased production of interleukin-6, -1𝛽 and tumor necrosis factor-𝛼 in LPS-activated Raw 264.7 cells. In addition, GEHS reduced LPS-mediated iNOS expression. Moreover I-𝜅B𝛼 expression was significantly induced by GEHS and NF-𝜅B expression was reduced by GEHS. Conclusions : These results suggest the clinical basis of GEHS for the treatment of inflammatory diseases.

Analysis of Traditional Chinese Medicine for Sudden Sensorineural Hearing Loss : Systematic Review of Randomized Controlled Trials (돌발성 난청의 한약 치료에 대한 최근 중의학 임상 논문 분석)

  • Choi, Ji-Young;Kim, Su-Jin;Jee, Seon-Young;Hwangbo, Min
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.35 no.2
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    • pp.28-48
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    • 2022
  • Objectives : The purpose of this study is to investigate the trend of traditional Chinese medicine for sudden sensorineural hearing Loss(SSHL) in Chinese journals. Methods : Chinese National Knowledge Infrastructure(CNKI) and Wanfang med online were used to search randomized controlled trials(RCTs) on SSHL which were published from January, 2017 to December, 2021. Results : Among Chinese studies, Tonifying and Replenishing medicinal(補益藥) and Exterior-releasing medicinal(解表藥) were the most frequently used medicine in treating SSHL. Acori Graminei Rhizoma(石菖蒲) was the most frequently used herb excluding Glycyrrhizae Radix(甘草). All studies reported that using Traditional Chinese Medicine alone or combining western medicne(WM) is more effective for treating SSHL than using WM alone, although one study reported the result is not statistically significant. Conclusions : In analysis of selected studies, co-treatment of traditional chinese medicine and WM can be more effective way for treating SSHL than using WM alone. Side effects of treating SSHL can also be reduced by co-treatment of traditional chinese medicine and WM.

안구건조증의 침 치료에 대한 최근 임상 연구 동향 분석 - 2010년 이후 Pubmed, Cochrane Library 검색 중심으로

  • Ji-One Im;Ji-Young Choi;Seon-Young Jee;Min Hwangbo
    • The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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    • v.36 no.2
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    • pp.10-25
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    • 2023
  • Objectives : The purpose of this review is to validate the effectiveness of acupuncture treatment on dry eye syndrome. Methods : Through foreign online databases(Pubmed, Cochrane Library) and domestic online databases(Science On, OASIS) we only searched for Randomized controlled trials(RCTs) that performed acupuncture for dry eye syndrome from January 2010 to December 2022. Results : The most commonly used acupoints were 風池(GB20), 贊竹(BL2) and the most commonly used meridian was the gall bladder meridian of foot-shaoyang. The most commonly used evaluation criteria was Tear Break Up Time(TBUT) followed by Schirmer Test and Ocular Surface Disease Index(OSDI). In most of 8 studies, acupuncture treatment showed significant therapeutic effects. Conclusions : According to this study results, acupuncture can be suggested to effective way for treating dry eye syndrome. More clinical studies are needed to prove the effectiveness of the acupuncture on dry eye syndrome.

Vibration Fatigue Analysis for Multi-Point Spot-Welded SPCC Structure Considering Change of Dynamic Response (동적응답의 변화를 고려한 점용접부의 진동피로해석)

  • Kang, Ki-Weon;Chang, Il-Joo;Kim, Jung-Kyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.9
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    • pp.1193-1199
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    • 2010
  • Spot welding is the primary method of joining sheet metals in the automotive industry. As automobiles are subjected to fatigue loading, some spot welds may fracture before the whole system has failed. This local fracture of spot welds may lead to change in the dynamic response and consequently affect fatigue behavior of an automobile. Therefore, this change in dynamic response should be taken into consideration to assess the fatigue life of structures subjected to spectrum loading, such as automobiles. In this study, vibration fatigue analysis was performed by taking into consideration the change in the dynamic response due to accumulated damage at spot-welded parts. Fatigue tests were carried out on tensile-shear spot-welded specimens under constant amplitude loading condition. And the fatigue life of spot welds under spectrum loading was predicted using vibration fatigue analysis method based on finite element analysis.