• Title/Summary/Keyword: Degradation characteristics

검색결과 2,234건 처리시간 0.031초

내구시험을 통한 베어링의 열화 특성과 그리스의 화학적 열화 특성 연관성 분석 (Correlation Analysis Between Chemical Degradation Characteristics of Grease and Degradation Characteristics of Bearing Through Durability Test)

  • 강보식;이충성;류경하
    • 한국산업융합학회 논문집
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    • 제25권6_3호
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    • pp.1239-1246
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    • 2022
  • This paper introduces the effect of grease on the degradation characteristics of bearings used as key components of packaging equipment and automation systems. Bearings parts are installed to fix and support the rotating body of the system, and performance degradation of the bearings has a great effect on the life of the system too. When bearings are used in various devices and systems, the grease is applied to reduce friction and improve fatigue life. Determining the type of lubricant (grease) is important because it has a great influence on the operating environment and lifespan and ensures long lifespan of systems and facilities. However, studies that simultaneously compared and analyzed the change in mechanical degradation characteristics and the comparison of chemical degradation characteristics according to grease types under actual operating conditions are insufficient. In this paper, three types of small harmonic drive, high-load reducer, and low-load reducer grease used in power transmission joint modules are experimentally selected and finally injected into ball bearings with a load (19,500N) to improve bearing durability. Degradation characteristics were tested by attaching to test equipment. At this time, after the durability test under the same load conditions, the mechanical degradation characteristics, that is temperature, vibration according to the three greases types. In addition, the chemical degradation characteristics of the corresponding grease was compared to present the results of mutual correlation analysis.

Analysis on the electrical degradation characteristics of 2G HTS wires with respect to the electrical breakdown voltages

  • Kang, Jong O;Lee, Onyou;Mo, Young Kyu;Kim, Junil;Bang, Seungmin;Lee, Hongseok;Lee, Jae-Hun;Jang, Cheolyeong;Kang, Hyoungku
    • 한국초전도ㆍ저온공학회논문지
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    • 제17권3호
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    • pp.37-40
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    • 2015
  • Recently, the electrical insulation design for electrical apparatuses is important to cope with the tendency of high voltage. The degradation characteristics of a superconducting coil due to an electrical breakdown should be considered to design a high voltage superconducting coil. In this paper, the degradation characteristics of 2G high temperature superconducting (HTS) wires are studied with respect to electrical breakdown tests. To analyze the dependency of the degradation characteristics of 2G HTS wires, the electrical breakdown tests are performed with AC(alternating current) and DC(direct current) voltage. All tests are performed by applying various magnitudes of AC and DC breakdown voltages. To verify the degradation characteristics of 2G HTS wires, the tests are performed with various 2G HTS wires with respect to stabilizer materials. The degradation characteristics of 2G HTS wires, such as Ic(critical current) and index number are measured by performing electrical breakdown tests. It is found that the characteristics such as Ic and index number can be degraded by an electrical breakdown. Moreover, it is concluded that the degradation characteristics of 2G HTS wires are affected by the stabilizer material and applied voltages. The cross-sectional view of 2G HTS wires is observed by using a scanning electron microscope (SEM). As results, it is found that the degradation characteristics of 2G HTS wires are concerned with hardness and electrical conductivity of stabilizer layers.

Hot electron에 의한 RF-nMOSFET의 DC및 RF 특성 열화 모델 (Hot electron induced degradation model of the DC and RF characteristics of RF-nMOSFET)

  • 이병진;홍성희;유종근;전석희;박종태
    • 전자공학회논문지D
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    • 제35D권11호
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    • pp.62-69
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    • 1998
  • Hot carrier 스트레스후의 RF-nMOSFET의 DC 및 RF 특성열화를 분석하기 위해 기존의 열화 모델을 적용하였다. 드레인전류 열화보다 차단주파수 열화가 심하였으며 RF-nMOSFET의 열화변화율 n과 열화변수 m은 기존의 bulk MOSFET의 것과 같았다. Multi-finger 게이트 소자에서 finger수가 많을수록 열화가 적게 된 것은 큰 소스/드레인의 저항과 포화전압에 의한 것임을 알 수 있었다. 스트레스의 후의 RF성능 저하는 g/sub m/과 C/sub gd/의 감소와 g/sub ds/의 증가에 의한 것임을 알 수 있었다. 기판전류를 측정하므로 RF소자의 DC 및 RF특성 열화를 예견할 수 있었다.

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Degradation characteristics of 2G HTS tapes with respect to an electrical breakdown

  • Kang, Jong O;Lee, Onyou;Mo, Young Kyu;Kim, Junil;Bang, Seungmin;Lee, Hongseok;Lee, Jae-Hun;Jang, Cheolyeong;Kang, Hyoungku
    • 한국초전도ㆍ저온공학회논문지
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    • 제17권1호
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    • pp.48-52
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    • 2015
  • The electrical insulation design for a superconducting coil system is important for developing high voltage superconducting apparatuses. Also, the degraded characteristics of superconducting tapes due to an electrical breakdown should be considered for superconducting coils design. In this study, the degradation characteristics of 2G high temperature superconducting (HTS) tapes were studied with respect to electrical breakdown tests. The degradation tests of 2G HTS tapes were performed with various stabilizer materials. The degradation characteristics of 2G HTS tapes such as critical current(Ic) and index number were observed by performing electrical breakdown tests. It was found that the characteristics such as Ic and index number can be degraded by an electrical breakdown. Moreover, it was concluded that the degradation characteristics of 2G HTS tapes were affected by a stabilizer material and applied breakdown voltage. The cross sectional view of 2G HTS tapes was observed by using a scanning electron microscope (SEM). As results, it is found that the degradation characteristics of 2G HTS tapes are concerned with hardness and electrical resistivity of stabilizer layers.

원전 펌프의 성능저하 특성 (Degradation characteristics of pumps in nuclear power plants)

  • 이도환;박성근;홍성대;이병학
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2008년도 춘계학술대회논문집
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    • pp.593-598
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    • 2008
  • In the present study, degradation characteristics of pumps in nuclear power plants were investigated to provide the information of degradation mechanism and stressors. The failure records of pumps for the periods 2000 to 2006 on INPO(Institute of Nuclear Power Operations) EPIX(Equipment Performance and Information Exchange System) DB were reviewed. The 1,834 failure records reveal that the critical areas of pump failures are bearing, mechanical seal, gasket/o-ring, shaft, impeller, coupling and packing. Based on the failure rate of critical areas, the important degradation mechanism and stressors were determined. Additionally, the relationship between degradation mechanism and stressors such as wear was examined. Finally, the monitoring parameters related to degradation and stressors were discussed for the future development of degradation evaluation and prognosis technology of pumps.

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Degradation Characteristics of Pr/Co/Cr/Er Co-doped Zinc Oxide Varistors by Impulse Current Stress

  • Nahm, Choon-Woo
    • Transactions on Electrical and Electronic Materials
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    • 제15권6호
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    • pp.348-352
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    • 2014
  • In light of the sure protection function, the most important factors of a varistor are the clamping voltage ratio and degradation characteristics. The degradation characteristics of Pr/Co/Cr/Er co-doped zinc oxide varistors were investigated by impulse currents (0.4~2.1 kA) stress for the specified content of $Er_2O_3$ (0.5 and 2.0 mol%). The varistor doped with 2.0 mol% $Er_2O_3$ exhibited the best clamp characteristics, with the clamp voltage ratio (K) in the range of K = 1.63~1.88 at the impulse currents of 5-50 A. However, the varistor doped with 0.5 mol% exhibited excellent electrical stability, with variation rates for the breakdown field, for the nonlinear coefficient, and for the leakage current density of -6.9%, -12.6%, and -14.3%, respectively, after application of an impulse current of 2.1 kA. In contrast, the varistor doped with 2.0 mol% was destroyed after application of an impulse current of 1.2 kA.

고온초전도 변압기를 위한 액체질소 중 절연 파괴, V-t. 열화 특성 (Breakdown, V-t and Degradation Characteristics of Insulation in Liquid Nitrogen for HTS Transformer)

  • Nguyen, Van-Dung;Joung, Jong-Man;Baek, Seung-Myeong;Lee, Chang-Hwa;Suck, Song-Hee;Kim, Sang-Hyun
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제53권6호
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    • pp.316-323
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    • 2004
  • HTS transformer is one of the most promising devices to supply enough electric energy for quick increase consumption. However, for practical design of the HTS transformer, it is necessary to establish the research on breakdown, V-t characteristics, degradation, and so on. In this paper, we discussed breakdown characteristics and V-t characteristics of polyimide/L$N_2$ and glass fiber reinforced plastic/$LN_2$ composite insulations. These composite insulations have been used as turn-to-turn and layer-to-layer insulations for HTS transformer respectively, Moreover, we investigated the degradation of these insulation samples after breakdown using microscope and SEM photograph.

분위기 온도와 플라즈마 방전에 의한 AC-PDP의 형광막 열화 특성 (The Degradation Characteristics of Phosphor Layers by Environmental Temperature and Plasma Discharge in AC-PDPs)

  • 김현;장상훈;태흥식;최경철
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제51권9호
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    • pp.443-448
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    • 2002
  • The degradation characteristics of R, G, B phosphor layers in AC-PDP, which is due to the discharge of plasma, are still unknown. For the successful commercialization of AC-PDP, the degradation of phosphor layers, caused by the plasma discharge must be investigated and improved. In this paper, the degradation properties of phosphor layers in AC-$PDP_S$ are investigated. It takes long time to investigate the degradation in real condition, so that the device for accelerating the degradation is devised. To prove the performance of the device, the visible emission characteristics of phosphor layers and discharge with the environmental temperature are examined. As a result, it is shown that the phosphor layers are easily degraded when the discharge is sustained under high environmental temperature condition. After accelerating the degradation of blue Phosphor layer((Ba,Eu)Mg$AI_10$$O_17$) for 48 hours, its luminance decreases about 38 % and the corresponding color purity deteriorates severely.

교류 순방향 바이어스에 따른 형광 OLED의 전계 발광 특성 (Electroluminescent Characteristics of Fluorescent OLED with Alternating Current Forward Bias)

  • 서정현;주성후
    • 한국표면공학회지
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    • 제50권5호
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    • pp.398-404
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    • 2017
  • In order to study the AC driving mechanism for OLED lighting, the fluorescent OLEDs were fabricated and the electroluminescent characteristics of the OLEDs by AC forward bias were analyzed. In the case of the driving method of OLED by AC forward bias under the same voltage and the same current density, degradation of luminescent characteristics for elapsed time progressed faster than in the case of the driving method by DC bias. These phenomena were caused by the peak voltage of AC forward bias which is ${\sqrt{2}}$ times higher than the DC voltage. In addition, the degradation of the OLED was accelerated because the AC forward bias had come close to the upper limit of the allowable voltage range even though the peak voltage didn't exceed the allowable range of the OLED. However, the fabricated fluorescent OLED showed little degradation of OLED characteristics due to AC forward bias from 0 V to 6.04 V. Therefore, OLED lighting by AC driving will become commercialized if sufficient luminance is realized at a voltage at which the characteristics of the OLED are not degradation by the AC driving method.

Degradation Behavior of 850 nm AlGaAs/GaAs Oxide VCSELs Suffered from Electrostatic Discharge

  • Kim, Tae-Yong;Kim, Tae-Ki;Kim, Sang-In;Kim, Sang-Bae
    • ETRI Journal
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    • 제30권6호
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    • pp.833-843
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    • 2008
  • The effect of forward and reverse electrostatic discharge (ESD) on the electro-optical characteristics of oxide vertical-cavity surface-emitting lasers is investigated using a human body model for the purpose of understanding degradation behavior. Forward ESD-induced degradation is complicated, showing three degradation phases depending on ESD voltage, while reverse ESD-induced degradation is relatively simple, exhibiting two phases of degradation divided by a sudden distinctive change in electro-optical characteristics. We demonstrate that the increase in the threshold current is mainly due to the increase in leakage current, nonradiative recombination current, and optical loss. The decrease in the slope efficiency is mainly due to the increase in optical loss.

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