• 한국정밀공학회지
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• 제15권2호
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• pp.114-123
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• 1998

In the end milling process, the information of the surface errors plays an important role in adaptive control systems for precision machining. As the measuring accuracy of the surface errors directly matches the control's, it is an important factor for evaluating the performance of the system. In order to obtain the surface errors, the prediction using the cutting force, torque, motor power etc. is frequently practiced owing to the easiness in measurement. In the implementation of the prediction, the information on the cutting depths make it concrete and precise. Actually the axial depth of cut limits the range of the calculation. In general, it is not easy to know the cutting depths due to irregular shape of workpieces, inaccurate positioning of them on the table of machine tool, and machining error in the previous cutting. In addition to, even if cutting depths are informed, it is difficult to match the individual position of the cutter on the varying shape of the work material. This work suggests an algorithm estimating the cutting depths based on cutting force and makes it precise to predict the surface error. The proposed algorithm can be applied in more extensive cutting situations, such as presence of the tool wear, change of the work material hardness, etc.

• 한국추진공학회지
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• 제9권4호
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• pp.16-22
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• 2005

두께가 얇고 길이가 긴 튜브 제품을 생산하기 위한 가공법으로는 유동성형에 의한 성형방법이 많이 이용되고 있으며 이는 다른 가공방법에 비해 성형에 필요한 핀이 적게 들고 유동성형에 의해 가공된 제품의 기계적인 강도가 우수하며 표면 품질이 우수하기 때문이다. 따라서 유동성형 기술은 산업현장에서 폭 넓게 이용되고 있다. 특히 스피닝과 유동성형은 자동차, 항공, 방위산업에 자주 이용되고 있다. 본 논문에서는 3개의 롤러를 가지는 후방유동성형에 대한 유한요소해석을 통해 가공깊이와 가공속도가 성형력에 미치는 영향을 살펴보았다. 다양한 가공깊이와 가공속도 조건에서 축방향과 반경방향의 성형력을 구하였다.

• Physical Therapy Rehabilitation Science
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• 제11권3호
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• pp.356-362
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• 2022

Objective: Extracorporeal shock wave therapy (ESWT) is a nonsurgical treatment alternative to surgery for various musculoskeletal diseases that have traditionally been difficult to treat conservatively, including calcific tendinitis, tennis elbow, and plantar fasciitis. This study evaluated the effect of focused and radial shock wave therapy for calcific tendinitis of the shoulder. Design: Randomized controlled study Methods: Forty participants with calcific tendinitis were randomized into focused shock wave therapy (FSWT, n=20) and radial shock wave therapy (RSWT, n=20) groups. Patients were examined before and one week after treatment. Pain intensity was subjectively assessed using the visual analogue scale and function was assessed using the Constant-Murley score (CMS) and range of motion (ROM). Results: The results showed a significant decrease in pain and significant increase in shoulder mobility and function in both groups. However, FSWT was significantly more effective than RSWT, based on CMS and ROM assessment. Conclusions: Although it is possible to raise the energy intensity of RSWT to increase the depth at which the energy becomes dispersed, higher energy intensity is associated with a greater risk of severe neurovascular damage, and that high-intensity stimulation can cause adverse effects such as pain and petechiae. Therefore, FSWT is considered to be a safe and effective method for treating tendinous lesions while minimizing adverse effects. In conclusion, both FSWT and RSWT can reduce pain and increase mobility and function. FSWT can be considered as an alternative for calcific tendinitis of the shoulder.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 봄 학술발표회 논문집
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• pp.47-52
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• 1994

In designing of slabs, a prediction of the punching shear capacity is one of important concerns. In this study, an equation was proposed to predict the punching shear strength of reinforced concrete slabs. The proposed equation depends on concrete compression strength, steel ratio, effective depth and slab radial length. The good correlation exists between the predicted punching shear strength and the measured.

• Journal of Astronomy and Space Sciences
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• 제8권1호
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• pp.53-61
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• 1991

UV light curve of 31 Cygni has been made from the IUE high dispersion specta. The depth of primary minimum of the light curve is 5.2 magnitudes because the B4 star's steep spectral gradient. The light curve has been analyzed by the method of Wilson and Devinney Differential Correction (WD). The radial velocities have been measured using the Mg II h lines. The spectroscopic elements have been determined by the method of WD. The change of the Mg II resonance doublet has been investigated based on the eight representative spectra taken at well distributed orbital phases.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1988년도 가을 학술발표회 논문집
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• pp.30-35
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• 1988

An analytical study was conducted using the Galerkin technique to determine the behaviour of thin fibre-reinforced and laminated composite pipes under soil pressure. Geometric nonlinearity and material linearity have been assumed. We assumed that vertical and lateral soil pressure are proportional to the depth and lateral displacement of the pipe respectively. And we also assumed that radial shear stress is negligible because the ratio of the thickness to the radius of pipe is very small. We, in this paper, discuss the effect of the number of layer, fiber orientation, and soil property.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1993년도 제18회 학술대회 초록집
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• pp.51-56
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• 1993

The conical bearing can be used to support the radial and thrust load simultaneously. Two circumferential grooves with discrete hole restrictions are made on the bearing surface in order to increase stiffness. In this paper, the dynamic characteristics of this type of bearings are calculated such as stiffness and champing coefficients. As a results of theoretical analysis, it is verified that there exist the groove depth and distance between two grooves which produce the maximum stiffness at the given bearing dimensions.

• Tribology and Lubricants
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• 제10권1호
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• pp.56-61
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• 1994

The conical bearing can be used to support the radial and thrust load simultaneously. Two circumferential grooves with discrete hole restrictions are made on the bearing surface in order to increase stiffness. In this paper, the dynamic characteristics of this type of bearings are calculated such as stiffness and damping coefficients. As a results of theoretical analysis, it is verified that there exist the groove depth and distance between two grooves which produce the maximum stiffness at the given bearing dimensions.

• 한국공작기계학회논문집
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• 제12권5호
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• pp.1-7
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• 2003

In order to predict vibrations occurred during end-milling processes, the cutting dynamics was modelled by using neural network and combined with structural dynamics by considering dynamic cutting state. Specific cutting force constants of the cutting dynamics model were obtained by averaging cutting forces. Tool diameter, cutting speed, fled, axial and radial depth of cut were considered as machining factors in neural network model of cutting dynamics. Cutting farces by test and by neural network simulation were compared and the vibration displacement during end-milling was simulated.

• 천문학논총
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• 제23권2호
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• pp.31-35
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• 2008

We present analytical approximations for calculating the scattering and escape of non-ionizing photons from a plane-parallel medium with uniformly illuminated by external sources. We compare the results with the case of a spherical dust cloud. It is found that more scattering and absorption occur in the plane-parallel geometry than in the spherical geometry when the optical depth perpendicular to the plane and the radial optical depth of the sphere are the same. The results can provide an approximate way to estimate radiative transfer in a variety interstellar conditions and can be applied to the dust-scattered diffuse Galactic light.