• Bulletin of the Society of Naval Architects of Korea
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• v.6 no.2
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• pp.5-10
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• 1969

A stepped bar with seimi-circular stress relieving groove near the fillet was subjected by axial tension in a polarized light field. On the stress concentration factor, the effect of the ratios of the fillet radius, the distance between two relieving grooves and the groove radius to the breath of the narrower portion of the stepped bar have been investigate. Observing the stress concentration in 48 models with various proportions, the conclusion arrived at were as follow: 1) If the fillet radius of the stepped bar is larger than half breadth of the narrower portion, the reduction of the stress concentrations can not be expected. 2) If the fillet radius is smaller than half breadth of the narrower portion of the stepped bar, the stress concentration can be droped to the reasonable range. 3) When the groove radius is larger than a quarter of the difference between the distance of two relieving grooves and the breadth of the stepped bar and smaller than a half of that, the stress concentration factors can have their possible minimum value. 4) When the sun of the breadth of the narrower portion of the stepped bar and twice of the relieving groove radius is smaller than the distance between two relieving grooves, minimum stress concentration can be obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.254-257
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• 1997

In this paper, we investigated the effects of gap length and tip radius influenced in breakdown of mineral based insulation oil Electrode system was needle-plane geometry It is to model conductive extrusions in oil filled electrical power apparatus. The tip radius of needle electrode was 5, 10, 20 and 25${\mu}{\textrm}{m}$, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. It was calculated electrical breakdown strength at tip using Mason\`s equation from breakdown voltage As gap lenght increased. breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by tole phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage. breakdown 7tr7ilgtll was higher wheal polarity of needle was negative than positive. It is because of the space charge effect ill accordance with the influence of liquid motion.

• Journal of the Korean Society of Safety
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• v.19 no.1
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• pp.56-59
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• 2004

In this paper, we investigated the influence of gap length and tip radius on breakdown of mineral based insulation oil. Applied voltages were DC and AC voltage. Electrode system was needle-plane structure. The tip radius of needle electrode was 5, 10, 20 and 25${\mu}m$, respectively. We measured breakdown voltage for each of tip radius with increasing electrode gap, 2mm to 12mm. Electric breakdown strength at tip was calculated using Mason's equation contained geometric figure. As gap length increased, breakdown strength increased linearly. But, as tip radius of needle increased, breakdown strength decreased exponentially. It can be explained by the phenomenon that electron is easily injected, as tip radius increases, and effective work function decreases. When appling DC voltage, breakdown strength was higher when polarity of needle was negative than positive. It is because of the space charge effect in accordance with the influence of liquid motion.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.113-119
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• 2000

There are two major factors which affect the cam design : the pressure angle and the radius of curvature, Cam shape will have an instantaneous radius of curvature at every point. Even though the design constraint of the pressure angle has been satisfied the follower may still not complete the desired contact motion. If the radius of the follower roller is larger than the concave(negative) radius on the cam it occurs the gap between the cam and the follower roller at the contact point. And also if the curvature of the pitch curve of the cam is too sharp the cam profile may be undercut. This paper proposes a new approach which uses the relative velocity of the follower roller parallel to the tangent line at the contact point on the cam surface for determining the pressure angle and the relative acceeration for determining the radius of curvature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.296-303
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• 1987

The composite gear which is composed of involute curve and circular arc has been studied. In the vicinity of pitch point, its profile is an involute curve, and in the dedenum, a circular arc. The curve in the dedendum is generated by the circular arc of the mating gear. Though the available range between minimum and maximum radius of circular arc can be given by existing tooth profile equation, there was no formulation which relates design parameters to the desired radius. It is attempted to get the formula for the radius of circular arc as a function of design parameters, such as unwounded angle, number of teeth, module, and pressure angle. The radius of circular arc, the chordal tooth thickness at working root circle, nominal bending stress, Hertz stress and contact ratio obtained from derived formula are compared with those of the existing design criteria. And these are compared with those of involute gear.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.39-45
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• 2022

In this study, we investigated whether the interference occurring in forming roll surfaces could be eliminated by increasing the radius of the variable section forming rolls. The surfaces of the rolls capable of forming products with different flange heights and bend angles with the bend line tilted at an angle of 1° from the longitudinal axis were created using the general CAD software CATIA. Roll interferences were determined for the change in the forming roll radius. The minimum gaps between the upper and lower roll surfaces were measured for the change in the forming roll radius, and the roll interferences were calculated from the difference between the measured value and the thickness of the product. It was observed that the thickness of the product had a slight effect on the roll interference when the thickness was between 0.8 and 1.2 mm. It was also observed that the roll interference could be eliminated by increasing the roll radius.

• Journal of radiological science and technology
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• v.33 no.1
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• pp.19-24
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• 2010

The aim of this study was to evaluate the change of bone mineral density according to distal radius rotation and the correlations of the lowest BMD measured by DXA at the lumba versus distal radius. The eleven males were projected distal radius by DR X-ray and the measurement of BMD by DXA of the appropriate position of the forearm were performed on 21 males. The healthy 11 and 21 volunteers without any history of operations, anomalies, or trauma were enrolled. The experiment was performed by two methods. First, The DR X-ray was measured distal radius of 11 males in pronation and supination with three, six and nine degrees, including a neutral position. The ROI was measured by the m-view program on the PACS monitor. Second, The DXA was measured distal radius of 21 males in pronation and supination with five and ten degrees, including a neutral position to evaluate the changes of BMD according to the rotation. A correlation of the BMD in the distal radius with BMD that lumbar spine was performed, along with analysis of the data by SPSS 12.0v. The mean rotation angle of the distal radius about eleven males DR X-ray measured $7^{\circ}$ of pronation (82%, n = 9), $6^{\circ}$ of supination and $0^{\circ}$ of neutral of (9%, n = 1), The total average rotation angle in 11 male was $5.1^{\circ}$ of pronation. The rotation angle of the distal radius about twenty one males on DXA measured $7.2^{\circ}$ of pronation (43%, n = 9), $7^{\circ}$ of supination (24%, n = 5), and $0^{\circ}$ of neutral (33%, n = 7), The total average rotation angle in 21 people was $4.1^{\circ}$ of pronation. The correlation of the analysis of lumba and distal radius were r = 3.0, p = 0.18. consequently, The correlation was not significance. Because BMD of lumba was not coverd for BMD of the distal radius, with a neutral position, Pronation is needed for BMD in the distal radius with the rotation angle measuring at the lowest BMD. the rotation angle about five degrees of pronation of the distal radius is recommended.

• Journal of Biomedical Engineering Research
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• v.41 no.2
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• pp.94-100
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• 2020

The purpose of this study was to present the models for classifying the wrist X-ray images by types and for segmenting the radius automatically in each image using deep learning and to verify the learned models. The data were a total of 904 wrist X-rays with the distal radius fracture, consisting of 472 anteroposterior (AP) and 432 lateral images. The learning model was the ResNet50 model for AP/lateral image classification, and the U-Net model for segmentation of the radius. In the model for AP/lateral image classification, 100.0% was showed in precision, recall, and F1 score and area under curve (AUC) was 1.0. The model for segmentation of the radius showed an accuracy of 99.46%, a sensitivity of 89.68%, a specificity of 99.72%, and a Dice similarity coefficient of 90.05% in AP images and an accuracy of 99.37%, a sensitivity of 88.65%, a specificity of 99.69%, and a Dice similarity coefficient of 86.05% in lateral images. The model for AP/lateral classification and the segmentation model of the radius learned through deep learning showed favorable performances to expect clinical application.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.23-31
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• 1999

The purpose of this study is to evaluate the relationship between axial length/corneal radius ratio and refractive error for human eye. Ocular components were measured Baush & Lomb keratometer, Holden-Payor pachometer, and Stoz Compuscan. Refractive error was measured by subjective refraction. The results were as follows; 1) Spherical equivalent refractive error and axial length/corneal radius ratio was very highly correlated with the correlation coefficient for -0.89. 2) Axial length/corneal radius ratio and axial length, vitreous chamber depth were highly correlated that the correlation coefficients were 0.82, 0.80 respectively. 3) Axial length/corneal radius ratio and anterior chamber depth, corneal power, corneal radius, lens power were correlated with the correlation coefficients for 0.57, 0.40, -0.39, -0.35 respectively. 4) There were no significant correlation between axial length/corneal radius ratio and lens thickness, and corneal thickness.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1200-1209
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• 1999

Prediction model was composed by optimal parameter estimation from best fitting on reactant temperature profile, inlet and outlet temperature of coolant and yield of dual fixed-bed catalytic reactor(FBCR) which was measured in the industrial field. In order to design the FBCR which could obtain maximum conversion and yield, we investigated the effect of catalyst bed length and reactor radius changes. An uniform activity FBCR showed the best performance at z = 2.8 m of total catalysst bed length in case of reactor radius r = 0.01241 m and z =2.80 m(upper layer: 1.88 m, lower layer: 0.92 m) under reactor radius r = 0.01254 m for a dual activities FCBR. In case of reactor radius changes, the axial temperature profile and maximum radial temperature was rapidly risen for radius increase. The reactor radius decrease showed the opposite result.