• 한국음향학회:학술대회논문집
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• 한국음향학회 1987년도 학술발표회 논문집
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• pp.39-39
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• 1987

자동차에서 발생되는 소음은 여러 가지 발생원으로부터의 복합적인 것으로서 차량의 속도가 고속화하면서 타이어 소음의 기여도가 매우 커지는 것으로 알려져 있다. 타이어 소음은 근본적으로 노면과 타이어의 상호작용에 의하여 발생되는 데 타이어/노면의 상호작용에 영향을 미치는 인자로는 마모상태, 차량속도, 하중, 공기압, carcass 구조, 타이어 온도등 여러 가지가 있으나 tread 모양과 노면의 상태에 가장 크게 영향을 받는다. 본 연구에서는 승용차용 155SR13 radial 타이어를 대상으로 하여 실내에 설치된 dynamometer를 이용하여 groove 의 개수, groove 길이, groove 폭, groove 깊이, groove 방향 등 트레드 패턴 인자가 발생소음에 미치는 기여도를 실험적으로 측정하고 트레드 패턴형상에 따른 소음도를 예측할 수 있는 실험식을 구했다. 또한 단일 groove 내에서 발생되는 소음의 시간신호를 측정하여 모델화하고 차량속도와 groove 사이의 간격에 따른 시간신호를 합성하고 이 신호로부터 FFT 알고리듬을 통해 소음 spectrum을 구하는 소음 예측 프로그램을 개발하였다. 비교적 단순한 tread 패턴에 대해 이를 적용한 결과 실험적으로 구한 spectrum과 상당히 유사함을 볼 수 있었다.

• Tribology and Lubricants
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• 제6권2호
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• pp.76-87
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• 1990

It is known that the effects of oil supply conditions on the characteristics of plain journal bearings are significant and especially the dynamic characteristics are affected by cavity region. For various shapes (axial groove, spiral groove, X-shape groove) and positions of oil grooves, the pressure distribution and the static performance of plain journal bearings are obtained with numerical methods. Elrods algorithm which implements JFO oil rupture/reformation boundary condition is used in order to take into account the effect of cavity region. It is shown that in the cases of axial groove or X-shape groove the load capacity and the attitude angle are affected by the groove position but the effect of spiral groove position is less significant.

• 전기학회논문지P
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• 제54권4호
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• pp.224-229
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• 2005

This paper presents a bidirectional pulse power electrochemical etching system for groove manufacturing of the dynamic bearings. To manufacture the dynamic bearing for the groove, it is very important to consider the depth and roughness. If the precision of the groove is not exact, we can not get the desirable performance for the target of the dynamic bearing. To make the groove of bearing precise, we propose the method of electrochemical etching system. In order to design the depth and roughness exactly, the bidirectional pulse power converter is proposed. With the bidirectional pulse power converter, we obtain the condition and the parameters of converter such as frequency, duty ratio, time, temperature, velocity, pressure and so on. In this paper, we get the experimental results to verify the precise groove manufacturing.

• 소성∙가공
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• 제17권5호
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• pp.328-336
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• 2008

A criterion which predicts wrinkle initiation on workpiece in groove rolling process based on finite element analysis is proposed. Fundamental idea considered in the criterion is using the difference between flat rolling which don't cause wrinkling at all and groove rolling which usually accompanies it. The proposed criterion assumes that irregular distribution of shear strain on workpiece during groove rolling is attributable to the initiation of wrinkling. The proposed criterion has been applied to roughing train in the rod mill of SEAH BESTEEL Inc. A new design of 2nd pass (square roll groove) was suggested, machined and applied. Results reveal that the proposed criterion could point out the location of wrinkle initiation and could reduce onset of wrinkle.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.235-242
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• 2000

In this paper, the dynamic characteristics of coupled herringbone groove journal bearings and spiral groove thrust bearings with conical motion were numerically analyzed, The bearing performance characteristics were calculated by the perturbation method and are solved by FDM. Stability of bearing was obtained from the threshold of instability.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.2760-2766
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• 2013

서론 : 본 논문은 전방 잠금형 금속판을 이용한 요골 원위부 골절 수술 후 나사못(screw)의 요골구 관통 유무를 확인하기 위한 방법으로 방사선 요골구 접선방향촬영법의 새로운 검사법을 제시하고자 한다. 재료 및 방법 : 요골구 접선방향 촬영 시 요골 원위부 거상 각도는 2.5, 5, 7.5, 10도와 전완골과 방사선 검출기와의 각도를 60, 70, 80도로 각각 변화시켜 촬영한 방사선영상에서 나사못의 요골구 관통유무를 분석하였다. 결과 : 요골구 접선방향 영상에서는 요골구를 관통하지 않은 경우와 요골구 내관통, 요골구 외관통인 경우가 각각 55명(63.95%), 9명(10.47%), 22명(25.58%)으로 분석 되었고, 요골구를 관통한 나사못의 길이는 0.43~2.72mm의 범위로 평균 1.06mm이었다. 요골구가 잘 묘사되는 방사선 촬영법은 요골 거상각도 2.5~7.5도에서 90%이상, 전완골과 방사선 검출기의 각도 70도에서 요골구가 80%이상 잘 묘사되는 것으로 분석 되었다. 결론 : 요골구 접선방향 촬영법은 요골 원위부 거상 각도 5도, 전완골과 검출기의 각도는 70도를 추천 한다.

• 한국기계가공학회지
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• 제11권1호
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• pp.88-94
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• 2012

An axle drive shaft with double joint shaft, cross kit and yoke has an important role by transferring power and changing steering angle between axle and wheel in power train system. It has been used widely in the heavy machinery requiring a high reliability in the power train system. At fatigue failures of the axle drive shaft with the long span, a relatively high stress concentration at a snap ring groove on the drive shaft brings to significant fatigue damages under repeated loading condition. As Peterson's suggestions on this study, a relief groove in the vicinity of the snap ring groove is applied by decreasing the stress concentration and improving the fatigue life of axle drive shaft. By using FEM analysis, the decreasing effect of the stress concentration and extended fatigue life are due to the change of design parameters related with size and location of the relief groove. The relief groove with the design parameters such as d/b=2.0 and r/h=1.2 enables to decrease the stress concentration of 22.3% and increase the fatigue life more than 3 times by comparing with no relief groove application.

• Journal of Welding and Joining
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• 제27권4호
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• pp.67-72
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• 2009

In this paper, arc characteristics of V groove joints using pulsed GMA welding were found out. The bevel angles of $22.5^{\circ}$ and $30.0^{\circ}$ were chose to make the V groove configuration with the groove angles of $45^{\circ}$ and $60.0^{\circ}$, respectively. In the experiment, the arc current waveform measurement and the high speed photography were taken to investigate the arc characteristics for a single-beveled asymmetric workpiece. Consequently, the welding current was changed abnormally around the edge of groove. As the arc moved close to the groove face, the welding current was increased rapidly because the welding arc was affected by the inclined surface. Also the welding current waveforms were measured for the double-sided symmetric workpiece to verify the previous measurements for the single-beveled workpiece, and similar current waveforms were found.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.333-336
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• 2008

The groove rolling is a process that transforms the bloom or billet into a shape with circular section through a series of rolling. Inhibition of surface defect generation in groove rolling is a matter of great importance and therefore many research groups proposed a lot of models to find the location of surface defect initiation. In this study, we propose a model for maximum shear stress ratio over equivalent strain to catch the location of surface defect onset. This model is coupled with element removing method and applied to box groove rolling of POSCO No. 3 Rod Mill. Results show that proposed model in this study can find the location of surface defect initiation during groove rolling when finite element analysis results is compared with experiments. The proposed criterion has been applied successfully to design roll grooves which inhibits the generation of surface defect.

• 대한기계학회논문집B
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• 제22권1호
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• pp.34-49
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• 1998

In this study, turbulent flows in a grooved channel are numerically investigated by Large Eddy Simulation (LES). Especially, a parametric study is carried out to study effects of length and depth of a groove on large-scale flow structures. For one test case, comparison of LES results with those of DNS reveals a good agreement even though the number of grid points of LES is only 6.5% of that of DNS. This confirms that LES is a suitable tool for a parametric study of turbulent flows. The subsequent parametric study using LES shows that the large-scale turbulent structures are significantly affected by the geometry of the groove. Especially, when the length of the groove is short such that the recirculation region occupies the entire groove, the turbulent flow in the groove becomes very weak in both mean and fluctuation quantities.