• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.138-143
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• 2005

Recently, it is much more required to approach the accurate shaft alignment analysis according to the tendency of active showing in large container vessel and that of the heavy weight of propeller in connection with it. Shaft alignment calculation lies upon how the pressure apply on bearings properly in operation of main engine and how the stress of shaft puts within that of limit of bearing material and how the movement of shaft is prospected owing to propeller forces and moments. Therefore, we have conducted the shaft alignment calculation of very large container vessel considering the deformation of hull structure and the propeller forces and moments and the static and dynamic condition of shaft. The calculation results show the pressure distribution of aft bush and the movement of shaft in bearing. The shaft alignment calculation helps the stable application of shaft alignment, which was proved in sea trial.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.194-202
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• 2008

In this study, we investigated the tribology behaviour of two different bearing materials. One of these alloys content is Cu(90)-Sn(10) alloy and is widely used in the automotive industry.The other is Al alloy. This bearing content is Al-Sn-Si-Cu. Therefore, it is required to study on the lublicating characteristics of bearing according to different materials. In this study, compressor bearings made by respectively "PTFE solid lubricant" and "AI alloy with superior load carrying capacity, rubbing and impact endurance", have gone through journal bearing test. Lubrication and abrasion characteristics are evaluated by analyzing the material characteristics of a scroll compressor bearing bush. The AI alloy bearing showed the most excellent lubrication and abrasion characteristics than Cu-Sn alloy under high load condition.

• 한국정밀공학회지
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• 제31권5호
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• pp.381-387
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• 2014

This paper introduces a system to machine micro-sized patterns effectively on surface based on micro-milling process using tools with simultaneous rotation and oscillation, oscillation micro milling. To review the effectiveness of proposed concept, we integrated a micro-spindle supported by active magnetic bearings with a precision 3-axis air bearing stage using double-wedge mechanism, and tested this oscillation milling. Two types of oscillation milling were tested, which are linear oscillation milling with a flat end mill and elliptical oscillation milling with a ball end mill with 0.3 mm of diameter. The spindle was rotating 110 krpm and workpiece was moving constant speed of 2~8 mm/sec during the oscillation milling. As the results, multiple oval shape dimples were generated in regular spacing, and the variation of elliptical motion made different shapes of patterns. The results showed that proposed oscillation milling can be successfully used for machining repeated micro-patterns.

• 한국음향학회지
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• 제18권6호
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• pp.9-16
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• 1999

이 논문은 측정잡음이 큰 수동소나체계의 각도정보만을 이용한 표적기동분석(TMA ; Target Motion Analysis) 기법 연구의 일환으로서 표적의 상태변수를 추정하는 순차적 추정자로 수정이득확장칼만필터(MGEKF : Modified Gain Extended Kalman Filter)를 사용하며, 이 MGEKF의 초기화를 위해 비선형 batch estimation 알고리듬을 제안한다. 수동표적추적 시스템의 가관측성(observability) 해석을 바탕으로 시스템의 가관측성의 향상을 통해 TMA 성능을 개선시킬 수 있는 관측자의 기동을 결정하는 실용적이면서도 효과적인 방법을 제안한다. 또한 가관측성 확보가 어려운 초기단계의 TMA를 위해 관측자의 진행방향과 표적의 각도정보와 같은 기하학적 자료와 시스템의 가관측성과의 관계를 나타내는 engagement boundary를 산출하여 가관측성이 큰 기하학적 관계를 갖는 위치로 관측자를 선기동(pre-maneuver) 시키는 방법도 제시한다. 제시하는 TMA 기법의 성능을 시뮬레이션을 통해 입증한다.

• 전산구조공학
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• 제8권3호
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• pp.67-74
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• 1995

본 연구에서는 면진수조의 2차원 동적 해석기법을 개발하고 축소모델을 사용한 진동대실험을 통하여 해석기법의 타당성을 검증하였다. 수조의 벽체는 집중질량을 사용하여 모델링하였으며 유체의 부가질량을 벽체의 절점에 부가함으로써 유체의 동수역학적인 영향을 고려하였다. 면진수조의 운동방정식은 벽체와 유체로 구성된 상부구조의 운동방정식과 바닥슬래브와 면진장치로 구성된 하부구조의 운동방정식을 연계하여 구하였다. 진동대 실험에서는 투명한 아크릴로 제작한 모형수조를 사용하였으며 면진장치는 4개의 고감쇠 적층 고무베어링(High Damping Laminated Rubber Bearing)을 사용하였다. 축소모델에 의한 실험결과는 대체적으로 해석결과와 잘 일치하였으며 계산결과가 다소 보수적인 것으로 나타났다.

• 소성∙가공
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• 제27권1호
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• pp.18-27
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• 2018

As one of the functional metal parts in steam turbine diaphragm assembly, the hollow-partitioned turbine nozzle (stator) has large and thick geometries, as well as an asymmetric configuration. Therefore it is hard to support a metal blank in the die cavity. To ease this situation and control posture and position of metal blank (workpiece), a blank support structure is newly introduced. The blank support structure is basically composed of enlarged arms from the blank, guide pins and linear bearings. It can help to control the intermediate blank without a critical sliding phenomenon. The operation mechanism of this blank support structure, during thick plate forming for the hollow-partitioned turbine nozzle stator, is first evaluated. A series of FEM-based numerical simulations, with respect to the width of the guide arm as geometric design parameters, are carried out to investigate its applicable range. As the results, it is observed the blank support structure for this thick plate forming can guide the workpiece to have stable posture during the plate forming process.

• 대한기계학회논문집
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• 제16권6호
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• pp.1141-1149
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• 1992

본 연구에서는 Davison이 제안한 견실 제어이론을 응용하여, 자기베어링에 의 해서 지지되는 로터계를 위한 중앙 집중식 서보제어기를 설계하였다. 삼각함수 형태 의 외란과 지령치에 대한 완벽한 영향회피와 추적을 위하여, 일반적 서보보상기(serv- ocompensator)를 MIMO 제어기에 내장하였다. 또한, 상기 제어기의 일부분(subset)으 로서, 중앙집중식 PID 제어기를 제안하였다. 제2장에 자기베어링에 의해 지지되는 강체 로터계의 동적 모델을 요약하였으며, 제3장에서 제어기법의 구축을 설명하고, 두 가지 형태의 제어기에 대한 성능 비교와 견실성의 한계를 보여주는 시뮬레이션 결과를 제 4장에 제시하였다.

• 한국소음진동공학회논문집
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• 제12권8호
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• pp.632-638
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• 2002

As the tangential flow inside the clearance of tribo elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance sleeve, anti-swirl injection balance sleeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.

• 드라이브 ㆍ 컨트롤
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• 제11권4호
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• pp.46-52
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• 2014

This study suggests a small-sized screw decanter specialized for dredging sites. Generally, conventional screw decanters are composed of a cylinder and a cone. However, the suggested screw decanter simply has a cone based on a cone-type bowl structure. In this research, a commercial analysis tool is used to establish an optimal design for the bowl and the screw conveyor. Moreover, the base frame, where the main bearings that support the spindle of the bowl and the screw conveyor are installed, is optimally designed considering the weight of the rotating body and the deflection caused by the high centrifugal force. Furthermore, the natural frequency range of the spinning body, the bowl and the screw conveyor, is applied to this base frame; it is designed not to correspond to the resonance frequency range and achieves stability as a result. This study suggests an optimal design for the rotating body and the base frame of a screw decanter considering its vibration characteristics. Such a design will prevent overuse of materials and help to reduce the weight and volume-and the price-of a screw decanter.

• 한국유체기계학회 논문집
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• 제12권6호
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• pp.41-46
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• 2009

This paper deals with the operating-speed (high-speed) balancing of a refinery gasoline HDS (hydrodesulfurization) process recycle-gas 8-stages compressor rotor. A low-speed balancing condition of the rotor was measured as maintaining the G2.5 level. But an inspection run of operating-speed balancing condition, using tilting-pad journal bearings of actual use, showed that while it could be continuously-operated safely at a rated speed of 10,500 rpm, the rotor would not be able to run over 11,000 rpm as the vibration increased very sharply, approaching 11,000 rpm. In order to cure that a series of operating-speed balancing, which first calculated balance correction-weights by applying the influence coefficient measured and calculated at 10,500 rpm and then implemented correction works, was carried-out. The final operating-speed balancing results showed that the vibrations at the bearing pedestals represented very good levels of 0.2 mm/s by decreasing to as much as the 1/10 of the original vibrations and particularly, even at a targeted maximum continuous operating speed, MCS, of 11,500 rpm the vibrations represented about 1 mm/s, which is the operating-speed balancing vibration specification of API. Therefore, the expansion of MCS was successfully accomplished through the operating-speed balancing.