• Title/Summary/Keyword: 내구성능평가

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Inter Propellant Seal Performance test for 75 ton Class Turbopump (75톤급 터보펌프 추진제 혼합 방지 실의 성능 시험)

  • Jeon, Seong-Min;Kwak, Hyun-Duck;Park, Min-Joo;Kim, Jin-Han
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.5
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    • pp.57-64
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    • 2010
  • A performance test of inter propellant seal for a 75 ton class turbopump is conducted using water to evaluate leakage and endurance performance. Each part of fuel pump side and oxidizer pump side for a prototype inter propellant seal has been tested for verifying endurance performance during total accumulated test time 2,100 sec in water. The fuel pump side part with one-stage seal of carbon floating ring shows average leakage rate 13.7 gram/sec under average seal differential pressure 9.4 bar. On the other hand, the oxidizer pump side part with two-stage seal assembly of carbon floating rings shows average leakage rate 7.3 gram/sec under average seal differential pressure 9.5 bar. After the endurance performance test, the inter propellant seal shows good physical condition. A leakage performance test of the inter propellant seal for cryogenic environment will be performed using LN2 in the near future.

Inter Propellant Seal Performance test for 75 ton Class Turbopump (75톤급 터보펌프 추진제 혼합 방지 실의 성능 시험)

  • Jeon, Seong-Min;Kwak, Hyun-Duck;Park, Min-Joo;Kim, Jin-Han
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.47-53
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    • 2010
  • A performance test of a 75 ton class turbopump inter propellant seal is conducted using water to evaluate leakage and endurance performance. Each fuel pump side part and oxidizer pump side part of a prototype inter propellant seal has been tested for verifying endurance performance during total accumulated test time 2,100 sec in water. The fuel pump side part with 1 stage carbon floating ring seal shows average leakage rate 13.7 gram/sec under average seal differential pressure 9.4 bar. On the other hand, the LOx pump side part with 2 stage carbon floating ring seal shows average leakage rate 7.3 gram/sec under average seal differential pressure 9.5 bar. After the endurance performance test, the inter propellant seal shows good physical condition. A cryogenic leakage performance test of the inter propellant seal will be performed using LN2 in the near future.

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Evaluation of Diffusion on Cement Mortar and Durability of Concrete Specimen Using Inorganic Coating Material and Surface Treatment System (무기질 도료 및 표면처리 시스템을 적용한 시멘트 모르타르와 콘크리트의 내구성 평가)

  • Kim, In-Seob;Lee, Jong-Kyu;Chu, Yong-Sik;Kim, Tae-Hyun;Shim, Kwang-Bo
    • Journal of the Korea Concrete Institute
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    • v.15 no.4
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    • pp.522-528
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    • 2003
  • Concrete has been considered as a semi-permanent structural material, because its excellent durability. However, such high durable structure is often attacked by some environmental condition such as chloride diffusion, carbonation and so on. In order to prevent the deterioration behaviors of concrete structures. We estimated durability of concrete when used surface treatment system and coatings by new type inorganic coating materials. Base on the results of chloride ion's diffusion test, the coated cement mortar had smaller transmitted quantity.

Durability Evaluation of Cathode Open-type Proton Exchange Membrane Fuel Cells Stacks (Cathode 개방형 고분자연료전지 스택 내구성 평가)

  • Yoo, Donggeun;Kim, Hyeonsuck;Oh, Sohyeong;Park, Kwon-Pil
    • Korean Chemical Engineering Research
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    • v.60 no.1
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    • pp.12-19
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    • 2022
  • Cathode open-type PEMFC (Proton Exchange Membrane Fuel Cells) stacks, which are widely used in small transport-type PEMFC, have a problem with poor durability. Through the accelerated durability test of the 13-cell PEMFC stack, we tried to find the cause of the degradation of the stack and to contribute to the improvement of the durability of the cathode open stack. A hydrogen/air boundary is formed during start-up/shut-down (SU/SD) due to the structural problem of the cathode open stack in which the cathode is open to the atmosphere and it is difficult to maintain airtightness, thereby deteriorating the cathode. In this study, it was possible to evaluate the durability in a relatively short time by reducing the 54% of the initial performance by repeating SU/SD 1,800 times on the cathode open stack. After dismantling the stack, each cell was divided into two and the performance was analyzed. Overall, the anode outlet MEA, which facilitates air inflow, showed more severe electrode deterioration than the inlet MEA, confirming that the hydrogen/air boundary formation during SU/SD is the main cause of degradation.

Effect of Steel Fiber Addition on the Mechanical Properties and Durability of High-Flowable Retaining Wall Material (고유동 흙막이 벽체 재료의 역학적 성능 및 내구성에 대한 강섬유 혼입률의 영향)

  • Donggyu Kim;Seungtae Lee
    • Journal of the Korean GEO-environmental Society
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    • v.24 no.6
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    • pp.13-20
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    • 2023
  • This paper is aimed to evaluate the mechanical properties and durability of high-flowable retaining wall material (RWM) with different levels of steel fiber (SF) content. To produce the specimens of RWM, some chemical agents such as superplasticizer (SP), air-entrained agent (AEA) and viscosity modifying agent (VMA) were added in the fresh RWM. The compressive and split tensile strength measurements were performed on the hardened RWM specimens at the predetermined periods. Additionally, surface electric resistivity and absorption tests according to ASTM standards were carried out to examine mechanical properties of RWM mixes. The durable performances such as chloride ions penetrability and freezing-thawing resistance of RWM mixes were experimentally investigated. As resutls, it was found that the performance of RWM mix with SF were much better than that without SF, especially at the 2% addition of SF. Thus, it is noted that the proper addition of SF in the RWM mix may have a beneficial effect to improve mechanical properties and durability of RWM mixes.

Experimental Study on Evaluation of Material Properties in Cement Mortar with Pond Ash (매립회를 사용한 시멘트 모르타르의 재료 물성 평가에 대한 실험적 연구)

  • Jung, Sang Hwa;Kim, Joo Hyung;Kwon, Seung Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.3
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    • pp.108-117
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    • 2013
  • Among the byproducts from thermal power plant using coal combustion, fly ash as mineral admixture is widely utilized in concrete manufacturing for its engineering merits. However residuals including bottom ash are usually reclaimed. This study presents an evaluation of engineering properties in cement mortar with pond ash (PA). For this work, two types of pond ash (anthracite and bituminous coal) are selected from two reclamation sites. Cement mortar specimens considering two w/c (0.385 and 0.485) ratios and three replacement ratio of sand (0%, 30%, and 60%) are prepared and their workability, mechanical, and durability performance are evaluated. Anthracite pond ash has high absorption and smooth surface so that it shows reasonable workability, strength development, and durability performance since it has dense pore structure due to smooth surface and sufficient mixing water inside. Reuse of PA is expected to be feasible since PA cement mortar has reasonable engineering performance compared with normal cement mortar.

Effect of Freezing and Thawing on the Flexural Behavior of Reinforced Concrete Beams damaged by cracks (균열발생으로 손상을 입은 철근콘크리트 보의 동결융해 사이클에 따른 휨 거동 특성)

  • Jang, Yong-Heon;Yun, Hyun-Do;Seo, Soo-Yeon;Choi, Ki-Bong;Kim, Yun-Su;Kim, Sun-Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.277-280
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    • 2008
  • Reinforced concrete structures have an excellent durability under a good construction and continuous maintenance. But reinforced concrete construction is influenced by atmospheric phenomena and it is creating a deterioration. One of the deterioration cause on concrete is a freezing and thawing action. Freezing and thawing leads to the reduction in concrete durability by the cracking or surface spalling. If we are carried out freezing and thawing, deterioration of reinforced concrete construction will be reduction. Therefore, this study was performed to investigate the flexural behavior of reinforced concrete beams exposed to freezing and thawing cycles. Thee presence of damage and cycles were considered as variablees in this study.

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Appraisal of Concrete Performance and Plan for Stable Use of EAF Oxidizing Slag as Fine Aggregate of Concrete (전기로 산화슬래그 잔골재를 사용한 콘크리트의 성능 평가)

  • Cho, Bong-Suk;Lee, Hoon-Ha;Yang, Seung-Kyu;Lee, Woong-Jong;Um, Tai-Sun
    • Journal of the Korea Concrete Institute
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    • v.21 no.3
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    • pp.367-375
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    • 2009
  • Recently, more focus is shift to imbalances in aggregate market supply and demand and an exhaustion of natural resources. In this situation, Electric arc furnace oxidizing slag (EAF slag) has high application possibility as aggregate for concrete due to similar property with general aggregate. However, it is inherent the problem which causes pop-out by free-CaO contained in slag In this study, we've got the plan to assure the chemical stability of EAF slag, and then experimentally tested the mechanical performance and durability for the fine aggregate used EAF slag. On this test result, we suggest the application plan. At the result of this study, it shows that EAF slag would reduce the surface defect such as pop-out due to natural aging for the fixed hour and adjustment the grain size of EAF slag. And mechanical performance and durability according to the replacement rate of concrete service, were revealed more than equal or equal compare to general aggregate. Hereafter, quality control must precede not to impede the beauty of concrete surface as assure the safety for aging and processing. And, to establish the environmental resource recycling system for by-products of steel, it should be made development of various application and guideline of quality control for the EAF slag aggregate. Moreover, it must be constantly studied all kind of engineering performance and durability for related to this study.

Estimation on the Durability of Metakaolin Concrete According to the W/B Ratio (물결합재비를 달리하여 제작한 메타카올린 혼입 콘크리트의 내구성능 평가)

  • Kim, Chun-Ho;Kim, Nam-Wook
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.4
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    • pp.84-91
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    • 2014
  • In this study, in order to find the improvement effect of metakaolin for using improvement of strength in concrete structures, it is investigated the diffusion coefficient of chloride ions and adiabatic temperature rise test. As a result, due to the mixing of metakaolin, it has been confirmed reducing diffusion coefficient of chloride ions and could prevent down of slump for use of adding fly ash. Therefore, ensuring resistance to chloride ion penetration into concrete, it is possible to enlarge the W/B ratio and reduce the adiabatic temperature rise by mixing of metakaolin. So, it is confirmed that the durability of concrete structures is increased.