• Title/Summary/Keyword: Operation Durability

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DURABILITY IMPROVEMENT OF A CYLINDER HEAD IN CONSIDERATION OF MANUFACTURING PROCESS

  • Kim, B.;Chang, H.;Lee, K.;Kim, C.
    • International Journal of Automotive Technology
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    • v.8 no.2
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    • pp.243-248
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    • 2007
  • The durability of a cylinder head is influenced by the thermal and mechanical history during the manufacturing process, as well as engine operation. In order to improve the durability of cylinder head, both load from engine operation and the preload conditions from the manufacturing process must be considered. The aluminum cylinder head used for a HSDI diesel engine is investigated to reduce the possibility of high cycle fatigue crack in this study. FE analysis is performed to elucidate the mechanism of high cycle fatigue crack in the HSDI diesel cylinder head. Two separate approaches to increase the durability of the cylinder head are discussed: reducing load from engine operation and re-arranging preload conditions from the manufacturing process at the critical location of the cylinder head. Local design changes of the cylinder head and modification of pretension load in the cylinder head bolt were investigated using FE analysis to relieve load at the critical location during engine operation. Residual stress formed at the critical location during the manufacturing process is measured and heat treatment parameters are changed to re-arrange the distribution of residual stress. Results of FE analysis and experiments showed that thorough consideration of the manufacturing process is necessary to enhance the durability of the cylinder head.

Development and Operation of Durability Mock-Up Test Facilities for Offshore Electricity Structures (해상 전력구조물 내구성 실증 실험장 구축 및 운영)

  • Pang Gi-Sung;Han Sang-Mook;Song Young-Chul;Kwon Byeong-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.265-268
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    • 2005
  • This paper discusses a strategy and status for development and operation of durability mock-up test facilities for offshore structures. The strategy is examplified and facilitated using an offshore transmission tower crossing the West sea and the Shihwha lake, which was designed and constructed 345kV T/L lines transmitting power from Yeong-Heung fossil power plant to Seoul metropolitan area. Various data for corrosion protection, aging, life-prediction of concrete and steel offshore structures can be obtained using the proposed mock-up test facility. Acquired data will be used for further research on durability, life-prediction, and retrofit of structures. It is important to maintain the safety of 345 kV Yeong-Heung transmission line crossing the Shihwha lake because the offshore structure is one of the critical electric facilities transmitting large power to the metropolitan area. Operation of the offshore transmission tower mock-up is expected to make a significant contribution to stable power supply.

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Development of an Unmanned Test System Based on Forklift for Mast Operation Durability (지게차 마스트 작동내구를 위한 실차 기반 무인시험장치 개발)

  • Cho, Jae-Hong;Na, Seon-Jun;Kim, Min-Seok;Park, Myeong-Kwan
    • Journal of Drive and Control
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    • v.19 no.4
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    • pp.70-76
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    • 2022
  • In this paper, we develops an unmanned test system for the purpose of realizing an actual forklift-based test-bed for the operation durability of the forklift mast. First, two robot actuators were applied to the lever to replace lever manipulation of the operator. For detecting the height of the fork and the tilt angle of the mast, the laser displacement sensor and the inclinometer were installed to the forklift. Next, the embedded control system was used to control the robot actuator with reference to test mode. Experimental evaluation verified that developed test system was effective and practical for the viewpoint of the repeatability of the test mode.

A Control Method of Bidirectional DC-DC Converter for Fuel Utilization and Durability Improvement in Fuel Cell Vehicles (연료전지자동차에서 연료이용률과 연료전지 내구성 향상을 위한 양방향 DC-DC 컨버터의 제어기법)

  • Jo, Jin-Sang;Jung, Sang-Min;Lee, Jin-Hee;Han, Soo-Bin;Choi, Se-Wan
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.5
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    • pp.428-435
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    • 2005
  • In this paper a power controller is proposed to accurately control the commanded power for charge and discharge operation of a bidirectional DC-DC converter so that durability is improved in hybrid systems such as fuel cell vehicles. Also, a control algorithm for charge and discharge operation is proposed to improve fuel utilization and keep battery SOC constant so that energy is effectively utilized.

Durability Evaluation of ER Fluids in Hydraulic Control Systems (유압제어시스템 적용을 위한 ER 밸브의 내구성 평가)

  • Kim, Do-Tae;Jang, Sung-Cheol
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.2
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    • pp.100-105
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    • 2007
  • Electro-rheological(ER) fluid and valve are fabricated and evaluated experimentally in its durability to utilize the hydraulic control systems for long term operation. The two-ports ER valve used in the experiment consist of twelve parallel multi-layer electrodes and provide a restriction to the passage of ER fluid because of the viscous pressure drop and a component induced by the electric field. The durability test of ER valve are performed by measuring the surface roughness of electrodes with variation of an electric field strength and test time(1000 or 1800min.). Also, the shear stress and shear rate are measured to evaluate the durability of ER fluid as function of time. After durability test, ER shear stress increases approximately proportional to the shear rate with applied electric field intensity, In the ER valve, the center line average height roughness(Ra) of copper electrode increases about 1.56 times and ten-point median height roughness(Rz) increases about 2.2 times after the durability test. An understanding of these durability is essential to predicting the service life of ER fluid and valves.

Manufacturing and operation experiance of Amorphous Alloy Gore Transformer (실계통 운전경험에 따른 아몰퍼스 변압기의 제조 및 운영방안)

  • Jeong, Yeong-Ho
    • Proceedings of the KIEE Conference
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    • 1998.07a
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    • pp.110-112
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    • 1998
  • Some recomendations for the manufacturing, operation and maintanance of amorphous alloy core transformer are presented through the operation experiance. Transformers on trouble was taken to pieces and tested from a viewpoint of durability, and low loss characteristics.

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ASSESSMENT OF PROPERTIES AND DURABILITY OF FLY ASH CONCRETE USED IN KOREAN NUCLEAR POWER PLANTS

  • Cho, Myung-Sug;Noh, Jae-Myoung
    • Nuclear Engineering and Technology
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    • v.44 no.3
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    • pp.331-342
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    • 2012
  • Since the opening of the Shin-Kori #1,2 in 2005, fly ash mixed concrete has been used for NPP concrete structures under construction in Korea with the aim of preventing aging and improving durability. In this paper, the quality suitability of fly ash manufactured in Korea is assessed and the basic physical properties of fly ash mixed concrete and its durability against primary causes of aging are verified through experimental methods. Because of the internal structure filling effect from the pozzolanic reaction of fly ash and the resulting improvements in mechanical performance in such areas as strength and salt damage resistance, the durability of fly ash mixed concrete is shown to be superior. It is judged that this result can be applied in measures not only for improving the safety of NPP structures in operation in Korea but also for implementing effective structure life management should extending the life of structures be needed in the future.

Durability Test for the Expansion Joint of High-Speed Railway Bridge (고속철도 교량 신축이음장치의 내구성 실험)

  • 김병석;곽종원;신호상;김영진;박성용;장익순
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10b
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    • pp.894-899
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    • 1998
  • To absorb the deformation of live load, thermal gradient, shrinkage and creep in bridge structures and general structures, expansion joint has to be established. Especially expansion joint for high-speed railway bridge has to accomodate the static and dynamic forces and it not only has the durability of itself but also maintain the durability of structure by preventing the leakage of water. The actual used product of expansion joint for high-speed railway bridge is only ones made in France, Germany and Japan. In this study, the development process and test results of developed expansion joint are introduced which has the functional operation and durability enough to apply to high-speed railway bridges, roadway bridges and general structures. The tests consist of fatigue-durability test of 3 million times by high-speed rail load, leakage test and jack-up test for verifying the possibility of exchanging it. The performance of developed expansion joint satisfy the specification of Korea High Speed Rail Construction authority.

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Lifetime prediction of bearings in on-board starter generator

  • Zieja, Mariusz;Tomaszewska, Justyna;Woch, Marta;Michalski, Mariusz
    • Advances in aircraft and spacecraft science
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    • v.8 no.4
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    • pp.289-302
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    • 2021
  • Ensuring flight safety for passengers as well as crew is the most important aspect of modern aviation, and in order to achieve this, it is necessary to be able to forecast the durability of individual components. The present contribution illustrates the results of a computational analysis to determine the possibility of analysing the prediction of bearing durability in on-board rotating equipment from the point of view of thermal fatigue.In this study, a method developed at the Air Force Institute of Technology was used for analysis, which allowed to determine the bearing durability from the flight altitude profile. Two aircraft have been chosen for analysis - a military M-28 and a civilian Embraer. As a result of the analysis were obtained: the bearing durability in on-board rotating devices, average operation time between failures, as well as failure rate. In conclusion, the practical applicability of this approach is demonstrated by the fact that even with a limited number of flight parameters, it is possible to estimate bearing durability and increase flight safety by regular inspections.

The Characteristics of Exhaust Emissions by Durability Test with Biodiesel Fuel (20%) in a Commercial CRDI Diesel Engine (상용 CRDI 디젤기관에서 바이오디젤유 20% 적용시 내구시험에 따른 배기배출물 특성)

  • Choi, Seung-Hun;Oh, Young-Taig
    • Journal of Biosystems Engineering
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    • v.33 no.6
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    • pp.379-383
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    • 2008
  • A CRDI diesel engine used to commercial vehicle was fueled with diesel fuel and 20% biodiesel blended fuel (BDF 20%) and tested at the Seoul-10 mode for 150 hours. Engine dynamometer testing was completed at regularly scheduled intervals to monitor the engine performance and exhaust emissions. To check the engine parts (valve, injector), the engine was inspected after 150 hours running test. It was concluded that there was no unusual deterioration of the engine, or the changes in engine power (below 1.9%), smoke (below 4.1%), NOx (below 3.7%) and durability characteristics in spite of operation of 150 hours run with BDF 20%. The difference of kinetic viscosity for engine oil (before and after durability testing) was below 0.19% at $100^{\circ}C$.