• Title/Summary/Keyword: Wear Ring

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Study on the Mechanical Face Seal Performance for a 7-ton-Class Turbopump (7톤급 터보펌프 기계평면실의 성능 시험 연구)

  • Bae, Joonhwan;Kwak, Hyun D.;Choi, Changho
    • Tribology and Lubricants
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    • v.32 no.5
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    • pp.154-159
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    • 2016
  • This paper presents an experimental study of the leakage performance and endurance performance of a mechanical face seal in the 7-ton-class turbopump of the Korea Space Launch Vehicle 2 third-stage engine. We install a mechanical face seal between the fuel pump and turbine to prevent the mixing of the fuel and turbine gas. We design and manufacture a prototype mechanical face seal, which has two parts, namely, a bellows seal assembly and mating ring. We set up a test facility to measure the leakage and endurance of the mechanical face seal. For the similarity tests, we use water under real operating conditions such as high rotational speed, high temperature, and high pressure. Through investigation of the leakage and carbon wear rate, it is possible to evaluate the performance of the mechanical face seal. The results of the leakage and endurance performance test demonstrate the absence of any leakage from the prototype mechanical face seal after a trial run and clarify that the acceptable wear rate fully satisfies the turbopump requirements. Finally, we install a qualified mechanical face seal in a 7-ton-class turbopump and perform a validation test in the turbopump real-propellant test facility in the Korea Aerospace Research Institute. The test results confirm that the mechanical face seal works well under real operating conditions.

Effect of Cu-Additions on the Hand-Over Layer of an Aluminum Alloy - Hardening for the Top Ring Groove of Automotive Piston by the Plasma Transferred Arc Welding Process -

  • Moon, J.H.;Seo, C.J.;Hwang, S.H.
    • International Journal of Korean Welding Society
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    • v.1 no.1
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    • pp.58-62
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    • 2001
  • The surface of AC8A Ah alloy was modified by adding the Cu powder using a Plasma Transferred Arc (PTA) welding process. Under the optimum fabricating conditions, the modified surface of AC8A Ah alloy was observed to possess the sound microstructure with a minimum porosity. Hardness and wear resistance properties of the as-fabricated alloy were compared with those of the 76 heat-treated one. In case of the as-fabricated alloy, the hardness of the modified layer was twice that of the matrix region. Although significant increase in the hardness of the matrix region was observed after T6 heat treatment, the hardness of the modified layer was not observed to change. The wear resistance of the modified layer was significantly increased compared to that of the matrix region. The microstructure of a weld zone and the matrix region were investigated using the optical microscope, scanning electron microscope (SEM), electron probe microanalysis (EPMA), and transmission electron microscope (TEM). The primary and eutectic silicon in the weld zone were finer and more curved than in the matrix region, while some precipitates has had been found therein. According to the TEM observation, the predominant precipitate present in the weld zone was the $\theta$'phase, which is precipitated during cooling by rapid solidification in PTA welding process. Improvement of hardness and wear properties in the weld zone in the as-fabricated condition can be explained based on the presence of $\theta$’precipitates and fine primary and eutectic silicon distribution.

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An Electrochemical Evaluation on the Corrosion Resistance of Welding Zone due to Kinds of Repair Welding Filler Metals and Post Weld Heat Treatment (보수용접봉의 종류와 용접후 열처리가 용접금속부의 내식성에 미치는 영향에 관한 전기화학적 평가)

  • Shin, Jae-Hyun;Moon, Kyung-Man
    • Corrosion Science and Technology
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    • v.9 no.6
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    • pp.310-316
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    • 2010
  • Recently a fuel oil of the diesel engine of the marine ship is being changed with heavy oil of low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine such as cylinder liner, piston crown, spindle and seat ring of exhaust valves are predominantly increased. In particular the degree of wear and corrosion of piston crown is more seriously compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weldment of the piston crown is a unique method to prolong the its life in a economical point of view. In this case, filler metals having a high corrosion and wear resistance such as stellite 6, Inconel 625 and Inconel 718 are mainly being used for repair welding. However it has been often happened that piston crown on the ship,s job site is being actually inevitably welded with mild filler metals. Therefore in this study, filler metals such as E4301, E4313 and E4316 were welded at SS401 steel as the base metal, and corrosion property of their weld metals in the case of post weld heat treatment or not was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 0.1% $H_2SO_4$ solution. Corrosion resistance of the weld metal of E4301 was better than the other weld metals in the case of no heat treatment, however, its resistance was considerably decreased with post weld heat treatment(annealing:$625^{\circ}C$, 2 hr) compared to other weld metals. The weld metals of E4313 and E4316 showed a relatively good corrosion resistance by post weld heat treatment.

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

  • Lee, D.H.;Park, S.G.;Hong, S.D.;Lee, B.H.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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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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Life Analysis of Ball Bearings by Accelerated Life Test (가속수명시험을 이용한 볼 베어링 수명분석)

  • 김형의;이윤표;유영철
    • Proceedings of the Korean Reliability Society Conference
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    • 2004.07a
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    • pp.335-342
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    • 2004
  • The failures such as flaking, wear, crack and seizing caused by the high contact pressure accompanied with sliding motion between inner or outer ring and ball are potential failures of ball bearing. In this research, we have qualitatively selected the efficient test items through the analysis of the life and potential failures of ball bearing. The bearing's failures are related closely to the whole system in using the bearing. So, the bearing itself requires an estimation of life in order to opreate the system safely. We have tested ten ball bearings. Our research has applied both radial and axial direction force of maximum torque conditions simultaneously for the accelerated life testing. The result is established by employing the weibull plot and compared the predicted life of ball bearing to the experimental result.

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Process variables and die life for cold forging (냉간단조용 금형 수명에 미치는 공정 변수의 영향)

  • Lee Y. S.;Choi S. T.;Kwon Y. N.;Rhyim Y. M.;Lee J. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.215-218
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    • 2005
  • For the production of cold forged parts with near-net-shape attributes, the quality of the tool system is responsible for an essential portion of costs fer the finished components. Therefore, a tool lift is one of the important issues on cold forging industry. There are many complicated variables related with tool life, such as material, heat-treatment, coating, lubricant, process design. In this study, heat-treatment of tool material and lubricant are investigated to improve the tool life. Deep cryogenic treatment of tool steel is very efficient to improve the wear resistance due to the fine carbide. And, friction factor of lubricants for cold forging are measured by the ring compression test. Zinc-Phosphate and $MoS_2$ lubricant is effective to sustain the friction factor under 0.1.

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FE Analysis on the Screwed Safety of a Valve for a LPG Bombe (LPG 용기용 밸브의 체결안전성에 관한 유한요소해석)

  • Kim, Chung-Kyun;Oh, Kyong-Seok
    • Journal of the Korean Institute of Gas
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    • v.11 no.4
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    • pp.79-84
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    • 2007
  • In this paper, the finite element analysis of a valve screw for a LPG cylinder has been presented on the leakage safety and strength one, which are computed and investigated by a contact normal stress and von Mises stress between a female screw of a valve and a male screw of a neck ring in a LPG bombe. The LP gas charging pressure of a LPG bombe is $8{\sim}9kg/cm^2$, which is pressurized to the screw sealing contact areas between a valve and a LP gas cylinder. The peak failures of the screw tooth height due to a scratch wear and chipping loss of the contact area may decrease screw tooth strength and increase a leakage of a LP gas. These are strongly affect to the contact normal and von Mises stresses of the valve screws. The FEM computed results show that the tooth height loss due to a wear and chipping failure of the screw peak does not affect to the LP gas leak and strength of a valve screw theoretically. But if the tooth wear of the screw height of a brass valve overpasses the critical strength safety of the valve, the valve screw may be failed in fastening the valve and a LP gas bombe suddenly.

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Corrosion Characteristics of Welding Zone by Types of Repair Welding Filler Metals and Post Weld Heat Treatment

  • Lee, Sung-Yul;Moon, Kyung-Man;Lee, Yeon-Chang;Kim, Yun-Hae;Jeong, Jae-Hyun
    • International Journal of Ocean System Engineering
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    • v.2 no.4
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    • pp.209-213
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    • 2012
  • Recently, the fuel using in the diesel engines of marine ships has been changed to a low quality of heavy oil because of the steady increase in the price of oil. Therefore, the wear and corrosion in all parts of the engine such as the cylinder liner, piston crown, and spindle and seat ring of exhaust valves has correspondingly increased. The repair welding of a piston crown is a unique method for prolonging its lifetime from an economic point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, often at a job site on a ship, a piston crown is actually welded with mild filler metals. Therefore, in this study, mild filler metals such as CSF350H, E8000B2, and 435 were welded to SS401 steel as the base metal, and the corrosion properties of the weld metals with and without post weld heat treatment were investigated using some electrochemical methods in a 0.1% $H_2SO_4$ solution. The weld metal welded with CSF350H filler metal exhibited the best corrosion resistance among these filler metals, irrespective of the heat treatment. However, the weld metal zones of the E8000B2 and 435 filler metals exhibited better and worse corrosion resistance with the heat treatment, respectively. As a result, it is suggested that in the case of repair welding with CSF350H and 435 filler metals, no heat treatment is advisable, while heat treatment is desirable if E8000B2filler metal is used with repair welding.

A Study on the Fashion of Islamic Image (이슬람풍 패션에 관한 연구)

  • Kim Joeng-a;Jeong Hyeon-nam;Yum Hea-jung
    • Journal of the Korean Society of Clothing and Textiles
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    • v.29 no.1 s.139
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    • pp.23-34
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    • 2005
  • The purpose of this study is to spread the public recognition for the style of Islamic dress has been ignorantly left and provide this as the basic data for Islamic fashion design. This treatise restricts the Islamic scope into the southeast Asia and confuted the study referring to Islam related books, treatise, domestic and foreign fashion magazines as well as newspaper articles, Internet and screen materials. The study results are as follows: Commonly Islam as a term of religious scope means complex cultural body based on Islam. 1. The Islamic social and cultural images were categorized as (1) conservative and sexual (2) simple, static, decorative and rhythmical (3) dark, violent, bright and amusing image. 2. Islamic nations' style of dress was characterized (1) surface decorative dress (2) practical outer garment (3) trousers style. 3. Both men and women basically put on trousers in children's stories and animations. In case of women, they wear skirts and according a social standing, tunic and caftan style jackets. As for men and women, Dey both wear turbans or chadors but in particular, wealthy classes put on a distinguishable turbans and chadors with splendid accessories. 4. The characteristics of Islamic fashion are lace decoration around a sleeve and the waist or blouse and harem pants with a elastic cord. In addition, they are splendid necklace and ring earings looking old, accessories with big pendants and dragging belts. These examples are shown in collections and streets.

A Study on the Costume of the Gods in the Ancient Roman Myths (고대 로마 신화에 등장한 신들의 복식 연구)

  • 임상임;추미경
    • Journal of the Korean Society of Clothing and Textiles
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    • v.25 no.5
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    • pp.945-956
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    • 2001
  • The costume for gods in the Ancient Roman myth was studied by examining in the embossed-carving, sculptures, mural-painting and various documents of the period. The clothes item, hairstyle, symbol & ornaments and shoes of the gods in the Roman myths were analyzed to understand the formative process in the religious costumes, and results are as follows. First, the costumes for male gods are the same as those for ordinary men lived in ages, including toga, paludamentum, tebenna, tunica. The costumes for female gods are also the same as those for ordinary women lived in ages, including stola, palla, tunica. Second, the hairstyle of male gods is short curled-hair, twisty roll-up hair and braid long-hair due to the influence of Etrurian in the early days. Another hairstyle is appeared in form of the laurelled-crown. The hairstyle of female gods is curled long-hair, chignon style and braid roll-up hair decorated with hairband. Third, the symbol & ornaments which represent the responsible possession of male gods, are appeared in beard, a stick of the message, arrow-case, offering-dish, antlered-glass, shield, spear-handle, as the superhuman forms, such as the lightning shape. For female gods they are is appeared plastron, a stick of the message, flower. some female gods wear necklace, foot-ring, bracelet. Fourth, male gods wear shoes in forms of sandal, buskin, boots, but all female gods are in barefoot. It could be explained by the fact that a man-centered society in the ancient roman is reflected in the world of gods. As mentioned, Gods costume in Roman myths was very similar to or nothing different from the ordinary peoples in Rome. However, they used corps, sacrifices or sepcific symbols depending on the fields that they were responsible for in order to be distinguished from the ordinary people. This is the result from the peoples expression that they should keep a close relationship with Gods hoping to be protected, and rely on them under whatever circumstances.

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