• Title/Summary/Keyword: 비정상 마모

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The effect of cylinder wear on the oil consumption (엔진시린더의 마모가 오일 소모에 미치는 영향)

  • 강석춘
    • Journal of the korean Society of Automotive Engineers
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    • v.13 no.4
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    • pp.18-25
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    • 1991
  • 디젤엔진에서 윤활오일의 소모량이 점진적으로 증가하는 것은 비정상적인 시린더 마모 때문이다. 시린더 라이너의 작동기구를 L-link 피스톤운동 측정장치로 조사하여 피스톤 top-land의 탄소분 축적이 비정상시린더 마모의 주요 원인임이 증명되었다. 또 피스톤 top-land의 축소는 마모 방지의 유용한 방법인 것으로 이론과 실제에서 입증되었다. 오일 소모와 시린더 마모에 영향을 미치는 다른 요소들에 관해서도 살펴보았다.

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A Study on Lubrication and Wear Monitoring Technology for 2-strok Low Speed Diesel Engine (저속 2행정 디젤엔진의 윤활 및 마모 모니터링 기술 적용 연구)

  • Ahn, Yong-Hee;Kim, Dae-Young;Park, Deuk-Jin;Kim, Se-Lak
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2006.06a
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    • pp.37-38
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    • 2006
  • 저속 2행정 디젤엔진의 대형화 및 고출력화에 따라 피스톤링 및 실린더라이너 등은 보다 가혹한 마찰/마모 조건에 노출되고 있으며 비정상적인 마찰/마모 등 윤활 관련 문제가 빈번하게 발생되고 있다. 이러한 마모 문제를 해결하기 위해 윤활 설계 개선, 윤활유 성능 개선, 마모 메카니즘 규명 등의 다양한 관점에서 대책안들이 연구되어 제시되고 있다. 따라서 본 연구에서는 실린더라이너의 이상 마모 현상 등을 방지하기 위한 윤활 및 마모 모니터링 기술 동향에 대해 살펴보고 윤활유 모니터링 시스템 개발 사례에 대해 소개 하고자 한다.

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Investigation of Abnormal Wear of Jig in Electric Resistance Welding (전기저항 용접 시 발생하는 지그의 비정상 마모현상 원인 분석)

  • Kim, Sun-Ho;Cho, Hang-Deuk
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.1
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    • pp.51-56
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    • 2015
  • This paper presents an investigation of abnormal wear of a contact jig between a nail and a nail fixture in electric resistance welding. To perform an analysis on the abnormal wear phenomenon, several methods are provided. Based on the theory of electric resistance welding, are analyzed. Using microscopic analysis, surface craters are observed. In the measurement of the electric current flow in the nail fixture, the current flow distribution is measured. From several analyses, the cause of abnormal wear in the contact jig is measured using the electric discharge of high current density at the inflow point of the electric supply to the nail fixture. An alternative shape for normal wear is proposed.

Designed tire wear and uneven wear determination system using only tire laser sensor (타이어 전용 레이저 센서를 이용한 타이어 마모도 및 편마모 판별 시스템 설계)

  • baek, Sung-hyun;Jang, Jong-Wook
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.05a
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    • pp.346-349
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    • 2015
  • Generally, in order to verify the degree of tire wear or abnormal wear, a driver or an auto mechanic checks the degree of tire wear and the existence of tire abnormality, directly with the naked eye or by way of using a gauge equipment. In case of such verification, individual subjective judgments may be involved or a driver may suffer heavy burdens to expend the time and cost for using the wheel alignment equipment. Therefore, this thesis will use a number of laser sensors to check the existence of abnormal wear and the degree of wear on each tire and develop a system checking the sides of tires to receive the tire information, so that subjective judgments may be overcome and objective and accurate judgments may be rendered.

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Full-mouth rehabilitation without changing the vertical dimension in patient with worn dentition (마모된 치열을 가진 환자에서 수직교합고경 변화 없이 수복한 증례)

  • Kim, Minuk;Kim, Nahong;Jang, Hee-Won;Lee, Yong-Sang
    • The Journal of Korean Academy of Prosthodontics
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    • v.54 no.2
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    • pp.160-166
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    • 2016
  • Although physiologic abrasion in normal range need not to be corrected, when hard tissue of teeth are worn abnormally fast, it can cause severe damage and destroy esthetics and, functional structure of occlusion consequently. To establish a correct occlusal plane and space for the patient with worn dentition, it is necessary to increase vertical dimension. However, actual occlusal vertical dimension remains unhanged with compensation for the increase of alveolar bone height equivalent to the decrease of teeth length. A 74-year-old male presented with worn dentition and fractured tooth. Based on the assessment of OVD including clinical findings, full-mouth rehabilitation without increase of OVD was planned. This case presents that a satisfactory clinical result was achieved by restoring the worn dentition without changing occlusal vertical dimension.

A Study on the adequate Aggregate Selection of the Exposed Aggregate PCC Pavements (골재노출 콘크리트포장의 적정 골재 선정에 대한 연구)

  • Kim, Young-Kyu;Chae, Sung-Wook;Lee, Seung-Woo;Yoo, Tae-Seok
    • International Journal of Highway Engineering
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    • v.9 no.4
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    • pp.117-127
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    • 2007
  • The exposed aggregate PCC(EAP) pavements have been successfully used in Europe and Japan as low-noise pavements. Coarse aggregate are exposed on the pavement surface texture of EAP by removing mortar of surface. The pavement surface texture should maintain not only low-noise characteristic but also adequate skid resistance level during the performance period. Skid resistance decreased with wearing and polishing of tire and pavement surface due to the repetition of tire-pavement contact. Since the tires mainly contact the exposed coarse aggregate, the shape and rock type of coarse aggregate significantly influence wearing and polishing of EAP pavements. The test for resistance to abrasion coarse aggregate by use of the Los Angeles machine(KS F 2508) and the method of test for resistance to abrasion coarse aggregate by use of the Accelerated Polishing Machine(ASTM D 3319-90) are generally used to evaluate polishing characteristics of aggregate. In this study, polishing of coarse aggregate of different five rock types were evaluated by KS F 2508(LA abrasion test) and ASTM D 3319-90(PSV method). The results of LA abrasion test and PSV method were contrary to each other. Since LA abrasion test is estimated the quantity of abrasion by the impact of aggregate, it may not be adequate to evaluate the polishing of aggregate by the repetition of tire. In the case of PSV method, the resistance of polishing is estimated the skid resistance variation of polished aggregate after repetition of tire. The PSV method is adequate for the evaluation on polishing of coarse aggregate. From the test results of PSV method, it was founded that rock type, specific gravity, coarse aggregate angularity, flat or elongated particles in coarse aggregate are significant to the resistance characteristic of coarse aggregate.

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Full mouth rehabilitation using removable partial denture in patient with loss of vertical dimension due to worn dentition (심한 치아 마모로 인해 수직 고경이 상실된 환자에서 국소 의치를 이용한 전악 수복 증례)

  • Shim, Eun-Young;Lee, Na-Young;Kang, Jeong-Kyung
    • The Journal of Korean Academy of Prosthodontics
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    • v.56 no.4
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    • pp.347-353
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    • 2018
  • Gradual attrition is a normal process of aging, but severe attrition causes occlusal disharmony, functional disorder and esthetic problems. The collapse of posterior support may cause attrition of anterior teeth, and loss of occlusal vertical dimension (OVD). And it induces the pathologic change of the TMJ, unaesthetic facial appearance and decreased masticatory function. In this case, 70 year-old male presented with decreased vertical dimension and esthetic problems due to worn dentition. Based on assessment of intraoral findings, diagnostic cast and radiographic examination, full-mouth rehabilitation with increase of OVD was planned. After 10 month follow-up, occlusal stability is maintained and through this procedure, satisfactory outcomes were achieved in esthetic and functional aspects.

Full-mouth rehabilitation of a patient with severe tooth wear using a gothic arch tracer and stabilization splint. (비기능적 습관에 의한 전반적인 마모 환자의 고딕아치 기록장치 및 교합안정장치를 통한 완전 구강 회복 증례)

  • Sungwoo Ju
    • Journal of the Korean Academy of Esthetic Dentistry
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    • v.32 no.1
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    • pp.23-32
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    • 2023
  • A patient with para-functional habits can cause widespread teeth wear, along with temporomandibular joint disorders and myofascial pain syndrome in the masticatory muscles. Prolonged teeth wear is associated with a decrease in vertical occlusal dimension, leading to issues such as changes in facial morphology, decreased masticatory efficiency, and temporomandibular joint disorders. To achieve a three-dimensional full-mouth rehabilitation in patients with decreased vertical occlusal dimension, accurate diagnosis, analysis, and proactive treatment planning are essential. Prosthetic treatment accompanied by the restoration of physiological vertical occlusal dimension and the re-establishment of a normal occlusal plane is necessary. This case report presents a full-mouth rehabilitation case involving a patient with overall teeth wear, showing decreased vertical occlusal dimension which results in discomfort in the temporomandibular joint and aesthetic dissatisfaction. The report highlights the successful outcome achieved through the use of occlusal stabilization splint for temporomandibular joint stability and Gothic arch tracing devices for the re-establishment of intermaxillary relationships. Also, through adjustments and adaptation assessment using provisional prostheses, favorable outcomes were achieved both functionally and aesthetically.

A Study on the Diagnostic System for Reactor Coolant Pump (원자로 냉작재 펌프 진단 시스템에 관한 연구)

  • 배용채
    • Journal of KSNVE
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    • v.8 no.4
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    • pp.723-732
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    • 1998
  • 원자력 발전소에서 운전되고 있는 원자로 냉각재 펌프는 대형 수직 펌프로서 증기 발생기로부터 원자로에 냉각재를 순환시키는 중요한 역할을 담당하고 있다. 원자로 냉각재 펌프는 운전 조건 및 각종 결함에 따라 진동, 열적 변형, 마모 등의 비정상 상태에서 운전될 수 있으며, 이로 인한 발전소 신뢰성 저하의 원인이 된다. 따라서 이 펌프의 감시 및 진단에 대한 연구가 계속되어 왔으며 각종 시스템이 설치 운용되고 있다. 그러나 미국내의 거의 모든 냉각재 펌프 감시 시스템은 펌프의 고진동 여부만을 나타내며 진동의 원인을 진단하기 어렵다. 본 연구에서는 최근까지 주로 발생되었던 미국내 원자로 냉각재 펌프의 문제점을 분석하고 이들의 원인별 진동 특성을 지식베이스화 하였으며, 진단시스템 개발을 위한 알고리즘을 제안하였다.

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A Study on the Establishment of Disc Braking Force Pattern to reduce the Wear Mass of Pad (패드 마모량 감소를 위한 디스크 제동력 패턴 설정에 관한 연구)

  • Kim, Seog-Won;Kim, Young-Guk;Kim, Ki-Hwan
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.786-791
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    • 2007
  • Korean high speed train(HSR-350x) has adopted a combined electrical and mechanical(friction) braking system. Brake blending control unit(BBCU) controls each brake system to fulfill the required brake performances such as braking distance, deceleration and jerk. Also the braking system should be designed considering the economical management, such as effective use of generated braking energy and the minimum wear of friction materials(a pad and a brake shoe). In this paper, we establish the disc braking force pattern that reduces the wear of pad in the disc braking system by minimizing the variance of the instantaneous disk baking energy during braking time, and compare the wear mass of pad between the conventional disc braking force pattern and the established results.

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