• Tribology and Lubricants
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• 제20권2호
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• pp.77-83
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• 2004

The purpose of the paper is to numerically investigate the acoustic noise characteristics of cylindrical roller bearings under radial load. For the sake of simplifying of the analysis, it was assumed that the cylindrical roller bearings are infinitely long. Furthermore, the effects of following on the noise of the bearing were also examined: the radial clearance of the bearing, the viscosity of the lubricant, and the number of the rollers. The results and discussions of the present paper could aid in the design of low-noise cylindrical roller bearings.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.74-77
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• 2000

Porthole die extrusion has a great advantage in the forming of hollow section tubes difficult to produce by conventional extrusion with a mandrel on the stem. Because of the complicated structure of die assembly, extrusion process as a forming of hollow section tubes has been investigated experimentally Therefore, analytic approaches that are useful in profitable die design and in the improvement of productivity are inevitably demanded Welding strength is affected by many parameters, which are such as extrusion ratio, extrusion speed, die shape, porthole number, bearing length, billet temperature and mandrel shape. In this paper, the parameters, which are such as billet temperature, bearing length and tube thickness, are examined. The welding pressures are examined through 3D simulation of non steady state and compared with experimental results.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.5-6
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• 2006

대형 저속 2행정기관을 탑재한 선박에서 축계배치와 관련된 선미측 후부 메인엔진 베어링의 손상이 증가하는 경향이 있다. 메인엔진을 포함한 선체는 최적화로 인하여 변형하기 쉬운 경향에 있고, 고출력을 요구하는 추진 축계는 이것과 반대의 경향을 가지므로 축계 배치 변화에 대한 감도가 높아져서 메인엔진 베어링의 손상이 발생하게 된다. 이러한 문제에 대한 대책으로 메인엔진 베어링을 포함한 보다 정확한 배치계산을 할 필요가 있다. 이 논문에서는 축계배치계산 고정도화의 일환으로 메인엔진 베어링 수가 베어링 반력에 미치는 영향에 대하여 검토한다.

• 한국음향학회지
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• 제22권6호
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• pp.482-488
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• 2003

선 배열을 이용한 빔 형성시 특정 지향 방향을 기준으로 반대 방향에 동일한 이득을 갖게 되어 수신단에서는 좌/우측 방위구분에 있어 모호성을 갖는다 이에 본 논문에서는 선 배열에 카디오이드 빔을 적용하여 좌/우측 방위 구분의 모호성을 해결하고, 아울러 어레이 합성 처리 기법을 사용하여 음원에 대한 공간적 데이터 수를 증가시키고 음원으로부터 얻은 정보를 코히어런트 합성 처리함으로써 배열 센서가 갖는 공간적인 분해능의 한계를 극복하였다. 시뮬레이션 결과에서는 좌/우측 방위 구분에 대한 성능을 어레이 합성 횟수에 따라 나타내었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.165-170
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• 2011

A large number of seismic isolation systems have been developed since the early 1970s. They are basically a combination of elastomeric bearing and energy dissipators. The investigation described in this paper analyzes shear property and the frequency dependence of Lead Rubber Damper(LRD). Lead Rubber Damper is similar in shape and performance property to Lead Rubber Bearing. Experimental condition ranges from 20 to 200% in share strain and from 0.1 to 1.0Hz in frequency. When the shear strain is increased, effective stiffness and damping ratio are decreased. When the frequency is increased, change of the behavior characteristic is subtle.

• 드라이브 ㆍ 컨트롤
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• 제9권4호
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• pp.26-31
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• 2012

Friction reduction between sliding hydraulic machine components is required to improve efficiency and reliability of hydraulic machineries. It is recently reported that surface texturing on sliding bearing surfaces can reduce the friction force highly. In this paper, numerical analysis is carried out to investigate the effect of dimple numbers and inlet boundary pressures on the lubrication characteristics of a parallel sliding bearing using a commercial computational fluid dynamics (CFD) code, FLUENT. The results show that the pressure distribution, load capacity, dimensionless friction force and leakage with dimple number and their locations, and inlet pressures. The overall lubrication characteristics are highly affected by dimple numbers and boundary pressure. The numerical method adopted and results can be used in design of efficient hydraulic machine components.

• 전기학회논문지
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• 제57권12호
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• pp.2202-2207
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• 2008

Bearingless SRM(Switched Reluctance Motor) is researched for high speed or special applications which can not use mechanical bearing such as bio pump. In this paper, a novel hybrid pole bearingless SRM is presented. The proposed hybrid pole bearingless SRM has salient poles for torque and suspending force production. Motor torque is controlled by the phase currents in torque pole windings, and the suspending force is controlled by suspending currents in four suspending windings for radial direction suspension. Because the proposed bearingless SRM has divided pole structure, mutual effects between torque current and suspending current are very lower than the conventional one's. From this structure, the number of power devices for power converter can be reduced for bearingless SRM driving. The proposed hybrid pole bearing less SRM is verified by the FEM analysis and experimental results.

• 대한조선학회지
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• 제19권4호
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• pp.19-29
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• 1982

Galerkin's finite element method is applied to a two-dimensional heat convection-diffusion problem arising in the hydrodynamic lubrication of thrust bearings used in naval vessels. A parabolized thermal energy equation for the lubricant, and thermal diffusion equations for both bearing pad and the collar are treated together, with proper juncture conditions on the interface boundaries. it has been known that a numerical instability arises when the classical Galerkin's method, which is equivalent to a centered difference approximation, is applied to a parabolic-type partial differential equation. Probably the simplest remedy for this instability is to use a one-sided finite difference formula for the first derivative term in the finite difference method. However, in the present coupled heat convection-diffusion problem in which the governing equation is parabolized in a subdomain(Lubricant), uniformly stable numerical solutions for a wide range of the Peclet number are obtained in the numerical test based on Galerkin's classical finite element method. In the present numerical convergence errors in several error norms are presented in the first model problem. Additional numerical results for a more realistic bearing lubrication problem are presented for a second numerical model.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1590-1606
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• 2006

Slider bearings are widely applied in mechanical systems, where the design needs cover increased load capacity, lowered friction and power consumption and creative designs. This work is governed to perform a parametric characterization, by generating a novel structure on the upper slider surface, which can formally be expressed in micro-machined wavy-form, where the individual and combined influences of various structural design parameters and boundary conditions, on the performance records, are also evaluated. Computations put forward that the contribution of the wave amplitude on power loss values is highly dependent on the level of inlet pressure; higher amplitudes are determined to increase power loss in the lowest inlet pressure case of 1.01, whereas the contrary outcome is determined in the higher inlet pressure cases of 3.01 & 5.01. Designing the slider bearing system, based on optimal load capacity, produced the optimum wave number ranges as 10-45, 7-11 and 5-8 for the pad inclinations of $5^{\circ},\;4^{\circ}$ and $3^{\circ}$ respectively.

• 한국지반신소재학회논문집
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• 제6권3호
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• pp.39-46
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• 2007

세계적으로 폐기물의 발생량이 급증하여 매립지의 숫자가 급증하고 있으나 사용이 완료된 매립지의 처리에 많은 어려움이 있다. 특히, 도시 폐기물 매립지는 인구밀집 지역과의 근접성, 부지개발에 따른 경제적 가치의 급등 등의 이유로 활용 가능한 새로운 건설부지로서 많은 관심이 집중되고 있다. 그러나, 폐기물 매립지반 위에 구조물을 축조할 경우, 특별한 안정처리 및 보강처리를 하지 않은 경우, 지반침하, 구조물에 대한 지지력 확보 등에 문제점이 발생될 수 있다. 따라서, 본 연구에서는 폐기물 매립지반위에 구조물을 축조할 경우, 지오그리드 및 지오셀의 보강 효과를 규명하고자 반복평판재하시험을 수행하여 주요 영향인자인 지지력증가비, 지반계수, 스프링상수, 탄성회복율 등을 평가하였다.