• KSTLE International Journal
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• 제4권2호
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• pp.37-42
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• 2003

One of the obstacles for a magnetic bearing to be used in the wide range of industrial applications is the failure modes associated with magnetic bearings, which we don't expect for conventional passive bearings. These failure modes include electric power outage, power amplifier faults, position sensor faults, and the malfunction of controllers. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate in spite of some faults in the system. In this paper, we designed a fault-tolerant magnetic bearing system for a turbo-molecular vacuum pump. The system can cope with the actuator/amplifier faults which are the most common faults in a magnetic bearing system. We implemented the existing fault-tolerant algorithms to experimentally prove the adequacy of the algorithms for industrial applications. As it turns out, the system can operate even with three simultaneously failing poles out of eight actuator poles.

• 산업경영시스템학회지
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• 제33권4호
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• pp.209-217
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• 2010

Reliability tools such as QFD and FMEA identify voice of customer related to product design, its use, how failures may occur, the severity of such failures, and the probability of the failure occurring. With these identified items, a development team can focus on the design process and the major issues facing the product in its potential use environment for the customer. The purpose of this research is to develop a reliability estimation process of agricultural machinery components using QFD, FMEA, and field failure data. Based on QFD method, customer requirements, engineering design elements and part characteristics were deployed. Using the field failure data, failures are investigated, and Weibull B10 life are estimated. This estimation process is useful for preparing the design input and planning the durability target.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.1053-1062
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• 1993

The effect of loading speed on soil failure was studied by using a high speed triaxial compression test. Tests were conducted at 0.35-6.2m/s loading speed to compress soil specimens of sandy loam at different moisture contents. The axial stress at fracture increased with increase in loading speed up to certain critical speeds, however they decreased as the speed up to certain critical speeds, however they decreased as the speed increased further. Experiments were also conducted in the field of sandy loam soil with the vibrating tillage tool. Tests were done at 0.33-0.85m/s tractor speed oscillating frequency 13.7hz and oscillating amplitude 59mm. The maximum oscillating velocity of tillage tool was 2.5m/s. It was observed that for the oscillating operation, initially draft slightly increased with increase in forward speed and then it decreased .For the non-oscillating operation, draft increased continuously with increase in forward speed. Approach of studying soil failure in the laboratory test can be related to the field experiments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.1014-1017
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• 2000

Reliability engineering is regarded as the major and important roll for all industry. And advanced manufacturing systems with high speed and intelligent have been developed for the betterment of machining ability. In this study, we have systemized evaluation of reliability for machinery system. We proposed the reliability assessment and design review method using analyzing critical units of high speed and intelligent machine system. In addition, we have not only designed and developed test bed system for acquiring reliability data, but also have constructing WEB system for suppling reliability which is provided in design phase. From this study, we will expect to guide and introduce the reliability engineering in developing and processing phase of high quality product.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.20-26
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• 2000

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2006년도 학술발표대회 논문집
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• pp.93-100
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• 2006

The failure of hydraulic hose assemblies is caused by the impulse pressure and repetitive motions of bending and stretching (flexing) used at high pressure pipe in the form of bursting Since it takes long time to observe the bursting for life analysis, we can reduce test time by the method of applying the Knockdown stress which is equivalent to 70% of initial bursting pressure on rubber hose assemblies with maintaining the failure mode equally In this study, after scale parameter, shape parameter, and acceleration factor by preforming the impulse pressure test until the hose bursts, and finally analyzed the accelerated life.

• 드라이브 ㆍ 컨트롤
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• 제19권3호
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• pp.32-38
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• 2022

The in-wheel drive gearbox for military special vehicles converts the high-speed & low-torque output generated by the electric servomotor, into low-speed & high-torque mechanical power. As the vehicle is remotely maneuvered in mountainous terrain, wet fields, rough terrain, etc., the gearbox must generate a maximum input speed exceeding 5,000 rpm, a maximum torque of 245 Nm, and MTBF of 9,600 km. The purpose of this study was to analyze the failure mode of the gearbox, to ensure the durability of the in-wheel drive gearbox. Also, the field load test data of the vehicle was analyzed, the acceleration durability test standards were established, the acceleration durability test was conducted, and the durability test results were analyzed as well.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.465-466
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• 2002

In any mechanical system consisting of gears, shafts and/or bearings, the majority of metallic particles deposited into and carried by the lubrication system originate from the deterioration of oil-wetted working surfaces, even in proper lubrication system, due to failure mechanism (s) such as wear, fatigue and fretting corrosion. Determination of the point at which transition from normal to abnormal or to actual damage occurs has become a focus of attention in research activities for years, because it has been recognized that reliable, economic operation can be achieved through appropriate preventative measures. Known collectively from 'all size wear debris analysis' as early failure detection, the methods of testing for damage differ considerably, range from a micron or a submicron size debris analysis to Magnetic Chip Detector (MCD) ferrous debris analysis. This paper will be focused on the utilization of the low-cost analysis techniques for evaluation of industrial machinery condition.

• Journal of Mechanical Science and Technology
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• 제14권2호
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• pp.152-158
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• 2000

The contents of this paper include the evaluation of corrosion characteristics and the behaviour of stress corrosion cracking (SCC) for the weldment and post weld heat treatment (PWHT) specimen and parent of HT -60 steel using a slow strain rate test (SSRT) in synthetic seawater. Corrosion characteristics were obtained from the polarization curves by potentiostat, and SCC phenomena were evaluated through the parameters such as reduction of area and time to failure by comparing the experimental results in corrosive environment with those obtained in air. Corrosion rate of the weldment was the fastest, followed by parent and PWHT specimen. SCC phenomena between the weldment of HT-60 steel and synthetic seawater were shown. Besides, SCC was dependent upon the pulling speed greatly. Maximum severity of SCC was obtained at a speed of $10^{-6}mm/min$, whereas SCC could not be seen almost at $10^{-4}mm/min$. The resistance to SCC for PWHT specimen was improved considerably compared that of the weldment at $10^{-6}mm/min$. In case of SCC failure, it was verified from SEM examination that brittle mode and lots of pits could be seen at the fractured region near the surface of the specimen.

• 한국신뢰성학회지:신뢰성응용연구
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• 제15권3호
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• pp.139-144
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• 2015

Track drive unit adopted in the small sized excavator generally have been used in the construction equipment under the 10 tons as the driving device with forwarding and reversing of excavator. It is required to study the accelerated life test applied by over torque and speed to test the durability life test reflected the many driving modes of small sized excavator and also need to equip the comprehensive performance and life test equipments to do the various performance tests. This study had analyzed the failure modes of the components, and calculated the equivalent loads investigated the used loads in the real field conditions and elicits the acceleration factor adopted in the inverse power model. Also, this study have considered the changes of the acceleration factor and the durability test time in the case of the rotary group and the bearing through analyzing the main failure modes. It was calculated the no failure test time about 2 samples and confidence level 90% and elicited the accelerated life time 720 hours.