• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1238-1245
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• 2007

A very abnormal vibration was occurred at the LP(low pressure) turbine continuously during the pre-operation for a 550MW class USC(ultra super critical) steam turbine. This vibration was initiated at the rotating speed of about 3,450 rpm and then the vibration amplitude was highly increased the number by $2{\sim}3$ times with the increase of the rotating speed to the rated speed (3,600 rpm). In this paper, this abnormal vibration named spike vibration. This spike vibration was caused by the rubbing between the rotating bucket tip seal and the lower half of spill strip. Also, this paper presents the mechanism of the spike vibration and the proper method to eliminate this abnormal vibration problem. This result would be good practice to find the solution of similar high vibration in the USC steam turbines for power plant as well as industrial rotating machineries.

• 한국추진공학회지
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• 제24권6호
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• pp.61-68
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• 2020

7톤급 터보펌프 실매질시험에서 계측된 고주파 신호인 가속도와 압력섭동에 대한 주파수 분석(waterfall, frequency spectrum), 실효값(RMS) 계산 등의 신호 처리를 통해 산화제펌프의 신뢰성을 평가하였다. 계측된 압력섭동 신호 분석을 통해 산화제펌프의 누설 유로에 위치한 산화제 후방 플로팅 링에 의한 강한 압력섭동이 발생하였고 이는 산화제펌프 입구 및 출구 압력과 가속도 신호에도 영향을 주는 것을 확인하였다. 터보펌프의 가속도 실효값 계산을 통해 정격 운용 조건에서의 터보펌프는 양호한 진동 성능을 보여주고 있으며 가속도 회전수 성분 중 축계에 영향을 주는 회전수 동기 주파수 성분이 강하게 나타나는 것을 확인하였다.

• 소음진동
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• 제7권3호
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• pp.467-475
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• 1997

A rotor-bearing system has been investigated, including internal damping and axial torque using finite dynamic elements. A procedure is presented for dynamic modeling of rotor-bearing system which consist of finite dynamic shaft elements, rigid disk, and bearing and seal. A finite dynamic element model including the effects of rotatory inertia, gyroscopic moments, axial force, and axial torque is developed using the frequency dependent shape function. The natural whirl speeds, stability, and unbalance response of rotor system are calculated on several cases and compared with the conventional finite elements.

• 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.

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.376-381
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• 2004

A rig was constructed to test the performance characteristics and compare the hydraulic forces exerted on a centrifugal type artificial heart impeller. A conventional shaft. seal and bearing system. while driven by a small electric motor. supported the impeller which was separated from the pump casing by a six degree of freedom force transducer (JR3 Ine). Radial (x. y) and axial (z) hydraulic forces were recorded and compared. At physiological operating conditions. the results indicate that the double entry/exit centrifugal pump encounters a smaller radial force and significantly reduced axial thrust. These experimental results are valuable in the design of a magnetic bearing system to suspend the impeller of a centrifugal artificial heart pump. This experimental technique may also be applied to evaluate the required capacity and predict the lifetime of contact bearings in marine pumps.

• 한국유체기계학회 논문집
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• 제12권5호
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• pp.47-53
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• 2009

A rotordynamic and detailed stability analysis in accordance with API 617 standard were performed with a turbo-compressor, which is one of key rotating machinery in refinery, petroleum, and power plants. The system is composed of rotor shaft, impeller, sleeve hub, balance drum, and coupling hub. The rotor system is supported by tilting pad bearings, which has 5 pads and pad on loading condition. The rotordynamic analysis specified by API 617 includes the critical speed map, mode shape analysis, Campbell diagram, unbalance response analysis, and stability analysis. In particular, the specifications of stability analysis consist of a Level 1 analysis that approximates the destabilizing effects of the labyrinth seals and aerodynamic excitations, and Level 2 analysis that includes a detailed labyrinth seal aerodynamic analysis. The results of a rotordynamic analysis and stability analysis can evaluate the operating compressor health and can be utilized as a guide of its maintenance, repair and trouble solution.

• 한국수소및신에너지학회논문집
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• 제26권2호
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• pp.192-198
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• 2015

Fault Tree Analysis to predict the lifetime in the design process of LNG compressor is considered. Fault Trees for P & ID of the compressor are created. Individual components that comprise the compressor are configured with the basic event. The failure rates in the PDS and OREDA are applied. As results, the system failure rate and the reliability over time are obtained. Further, the power transmission and the shaft seal system is confirmed to confidentially importantly contribute to the overall lifetime of the system. These techniques will help to improve the reliability of design of large scale machinery such as a plant.

• 한국터널지하공간학회 논문집
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• 제17권4호
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• pp.473-485
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• 2015

디스크커터 내부부품의 손상과 관련된 원인은 씰(seal)부의 손상으로 인한 윤활유 부족, 토사 및 수분의 침투, 과부하, 과열, 조립문제, 소재문제 등이 있으며 손상 정도에 따라 디스크커터의 작동여부, 즉 회전이 가능한지가 나타난다. 따라서 디스크커터 회전문제에서의 핵심은 베어링의 작동여부라고 할 수 있다. 본 연구는 TBM의 굴착도구인 디스크커터의 재활용에 도움이 되고자 현장 적용된 디스크커터를 회수한 후 분해하여 내부부품을 조사하고 분석하였다. 그 결과, 허브의 부하영역에서의 스크래치는 재활용을 위해 가공작업이 필요한 것으로 나타났으며, 플로팅 씰의 래핑면과 오일상태는 재활용을 위한 성능파악에 필요한 시험으로 판단되었다. 특히 플로팅 씰은 베어링의 정상작동여부에 중요한 영향을 미치는 부품으로 파악되었다. 그 외의 베어링, 샤프트, 씰 리테이너에서는 특이사항이 없는 것으로 나타났다.

• Journal of Biosystems Engineering
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• 제43권1호
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• pp.1-13
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• 2018

Purpose: The development of compact tractors that can be used in dry fields, greenhouses, and orchards for pest control, weeding, transportation, and harvesting is necessary. The development and performance evaluation of power transmission units are very important when it comes to tractor development. This study evaluates the performance of a driving power transmission unit of a 50 kW multi-purpose narrow tractor. Methods: The performance of the transmission and forward-reverse clutch, which are the main components of the driving power transmission unit of multi-purpose narrow tractors, was evaluated herein. The transmission performance was evaluated in terms of power transmission efficiency, noise, and axle load, while the forward-reverse clutch performance was evaluated in terms of durability. The transmission's power transmission efficiency accounts for the measurement of transmission losses, which occur in the transmission's gear, bearing, and oil seal. The motor's power was input in the transmission's input shaft. The rotational speed and torque were measured in the final output shaft. The noise was measured at each speed level after installing a microphone on the left, right, and upper sides. The axle load test was performed through a continuous equilibrium load test, in which a constant load was continuously applied. The forward-reverse clutch performance was calculated using the engine torque to axle torque ratio with the assembled engine and transmission. Results: The loss of power in the transmission efficiency test of the driving power unit was 6.0-9.7 kW based on all gear steps. This loss of horsepower was equal to 11-18% of the input power (52 kW). The transmission efficiency of the driving power unit was 81.5-89.0%. The noise of the driving power unit was 50-57 dB at 800 rpm, 70-77 dB at 1600 rpm, and 76-83 dB at 2400 rpm. The axle load test verified that the input torque and axle revolutions were constant. The results of the forward-reverse clutch performance test revealed that hydraulic pressure and torque changes were stably maintained when moving forward or backward, and its operation met the hydraulic design standards. Conclusions: When comprehensively examined, these research results were similar to the main driving power transmission systems from USA and Japan in terms of performance. Based on these results, tractor prototypes are expected to be created and supplied to farmhouses after going through sufficient in-situ adaptability tests.

• 대한의용생체공학회:의공학회지
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• 제19권1호
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• pp.33-38
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• 1998

심장내 이식형 축류 혈액 펌프의 개발을 시도하였다. 이 펌프는 해부학적인 적합성이 좋고, 혈액과 접촉하는 면적이 적으며, 심장판막의 위치에 이식할 수 있어 이식술이 용이한 등의 이점이 있다. 축류혈액펌프는 입펠러와 소형 모터에 의해 구성되었으며, 모터축과 펌프의 본체의 밀봉은 자성유체 축봉이 이용되었다. 본 연구에서 개발한 혈액펌프의 펌프 특성은 4매 임펠러의 경우 회전수 7091[rmp], 6매 임펠러의 경우 회전수 6402[rpm]에서 유량 5[l/min], 차압 100[mmHm]을 얻을 수 있었으며, 자성유체 축봉의 내압 특성은 회전수 7000[rpm], 압력ㄹ 150[mmHg]에서 24시간 이상의 내구성을 얻을 수 있었다. 그리고, 용혈에 대하여 검토한 결과 4매 임펠러의 1H 는 0.0561[g/100L]이고, 6매 임펠러의 경우는 1H=0.214[g/100L]을 얻을 수 있었다. 이상의 실험결과는 심장내 이식 축류형 혈액펌프의 실현 가능성을 보여 주는 것으로 앞으로 큰 기대를 걸수 있다고 생각된다.