• Journal of Industrial Technology
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• v.12
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• pp.69-76
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• 1992

An attempt has been made to determination the NC milling machine's tool-path through the adaptive parabolic interpolation method & the adaptive linear-parabolic interpolation method in consideration of the economical machining time. The algorithms for the above-mentioned interpolation methods have been designed and the numerical experiments for these methods have been conducted with the existing adaptive linear interpolation methods for comparision.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2001.11a
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• pp.111-117
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• 2001

The problem of the vibration of arches has become a subject of interest for many investigators due to Its importance in many practical applications. The early investigators into the in-plane vibration of rings were Hoppe $^{1)}$ and Love $^{2)}$ . Love $^{2)}$ improved on Hoppe's theory by allowing for stretching of the ring. Lamb $^{3)}$ investigated the statics of incomplete ring with various boundary conditions and the dynamics of an incomplete free-free ring of small curvature.(omitted)

• Journal of the Korean Magnetics Society
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• v.14 no.3
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• pp.105-108
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• 2004

Array of magnetic Ni nanostructures has been fabricated on Si substrate by using nanoporous alumina film as a mask during deposition. The nanostructures are truncated cone-shape and the lateral sizes are comparable to height. While the continuous film shows well-defined in-plane magnetization, the nanostructure shows perpendicular component of magnetization at remanence. The hysterectic behavior of nanostructures is dominated by the demagnetizing field instead of interaction among them.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.517-524
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• 1995

This study was conducted to investigate the characteristics of the road alignment, correlations among evaluation factors of the alingment, and the relationships between the evaluation factors and terrain factors for the forest road of five National Forest Offices. The results were as follows : 1. The elongation coefficients(${\eta}$) of forest road in Kangnung and Wonju National Forest Office were ranged 0.3~0.5, and those of Andong, Namwon, and Kongju National Forest Offices were ranged 0.2~0.3 in straight line of 100m, 200m, and 300m. 2. Three different types of plane alignment were identified for Kangnung and Wonju National Forest Offices, Namwon and Kongju National Forest Offices, Andong National Forest Office. However, longitudinal alignment for five National Forest Offices tended to be similar conditions. 3. Low correlation coefficients were calculated in the relation between elongation coefficients(${\eta}$) and evaluation factors of plane alignment(curve length ratio(%), sum of inverse number of each curve radius(m/km), and sum of each intersection angle($^{\circ}/km$)) for three straight lines. On the contrary, high correlation coefficients were obtained among the relations of curve length ratio(%), sum of inverse number of each curve radius(m/km), and sum of each intersection angle($^{\circ}/km$). 4. Slope(%) were closely correlated with plane alignment, and so were the relationships between frequency of valleys and streams(No./km) and elongation coefficients(${\eta}$) of forest road.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.161-168
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• 2015

Horizontally curved bridges are subjected to torsional loads by their vertical dead loads only as well as eccentric loads, which cause negative reactions at supports. In this paper, effects of bridge curvature on vertical reactions at supports are investigated for 48.8 m length simple span steel box girder bridges with elastomeric bearings by varying curvature angle from 0.49 to 1.35 rad. In order to expect magnitude and direction of reactions including possibility of negative reactions, reaction evaluation equations have been analytically developed by separating a superstructure of curved bridge into independent components. Concrete slabs and bottom flanges in steel box section are assumed geometrical annular sectors in area dimension, and top flanges and webs that have very narrow projected areas are assumed geometrical arcs in line dimension. Proposed equations have relatively simple forms and prediction values are on very good agreement with those from finite element analyses by difference of 1% order.

• Journal of Digital Contents Society
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• v.16 no.6
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• pp.909-916
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• 2015

This paper presents a method to display the 3D vector fields by analyzing phase space. This method is based on the connections between ordinary differential equations and the topology of vector fields. The phase space analysis should be geometric interpolation of an autonomous system of equation in the form of the phase space. Every solution of it system of equations corresponds not to a curve in a space, but the motion of a point along the curve. This analysis is the basis of this paper. This new method is required to decompose the hexahedral cell into five or six tetrahedral cells for 3D vector fields. The critical points can be easily found by solving a simple linear system for each tetrahedron. The tangent curves can be integrated by finding the intersection points of an integral curve traced out by the general solution of each tetrahedron and plane containing a face of the tetrahedron.

• Journal of the Korean Magnetics Society
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• v.11 no.5
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• pp.179-183
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• 2001

Magnetoresistance and Planar Hall effect of Glass/Ni$\sub$83/Fe$\sub$17/(2 nm)/[Cu(2 nm)Ni$\sub$83/Fe$\sub$17/(20 nm)]$\sub$50/ multilayer were measured. Repeated saw tooth like planar Hall effect signal was observed in the range of magnetization reversal process, while no sign of such saw tooth was observed in Magnetoresistance diagram. For the reason of saw tooth like signal, it is supposed that subsequent abrupt domain wall motion of each magnetic layer in the process of magnetization reversal process was observed in planar Hall effect in transverse direction to the current direction. This fine structure of planar Hall effect was observed for applied fields in any direction. Magnetoresistance curve did not show this fine structure of magnetization reversal, of course, since only net magnetization of each layer has to do with the resistivity. Extended research on the reason of this sawtooth like signal should be conducted.

• Journal of Korean Society of Transportation
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• v.22 no.3 s.74
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• pp.109-125
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• 2004

In recent decades, microscopic simulation models have become powerful tools to analyze traffic flow on highways and to assist the investigation of level of service. The existing microscopic simulation models simulate an individual vehicle's speed based on a constant free-flow speed dominantly specified by users and driver's behavior models reflecting vehicle interactions, such as car following and lane changing. They set a single free-flow speed for a single vehicle on a given link and neglect to consider the effects of highway design elements to it in their internal simulation. Due to this, the existing models are limitted to provide with identical simulation results on both curved and tangent sections of highways. This paper presents a model developed to estimate the change of free-flow speeds based on highway design elements. Nine neural network models were trained based on the field data collected from seven different freeway curve sections and three different locations at each section to capture the percent changes of free-flow speeds: 100 m upstream of the point of curve (PC) and the middle of the curve. The model employing seven highway design elements as its input variables was selected as the best : radius of curve, length of curve, superelevation, the number of lanes, grade variations, and the approaching free-flow speed on 100 m upstream of PC. Tests showed that the free-flow speeds estimated by the proposed model were statistically identical to the ones from the field at 95% confidence level at each three different locations described above. The root mean square errors at the starting and the middle of curve section were 6.68 and 10.06, and the R-squares at these points were 0.77 and 0.65, respectively. It was concluded from the study that the proposed model would be one of the potential tools introducing the effects of highway design elements to free-flow speeds in simulation.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.25-31
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• 2010

Road design guideline provides the directions on how to design a road alignment based on design speed, and this guideline has a design expectation in that design speed is supposed to be equal to the operating speed of drivers. Horizontal curve design is also based on design speed, and minimum radius is derived based on the drivers comfort while negotiating the curve. However, side friction reflecting drivers comfort is lower than a physical friction measured on wet road surface, therefore, it is reasonable to regard the criterion on minimum radius has a safety margin. Futhermore, the practical preference of choosing the larger radius than minimum leads to a noticeable gap between design speed and operating speed, so links to the violation of design expectation implicated in the guideline. In order to review this assumption, friction and operating speed at rural roads was measured and observed. As the results, a safety margin brought out by the gap between comfort-based friction and measured friction is qualitatively derived. Also, the gap between design speed and operating speed presumably caused by the safety margin and practical preference is analysed. By this, it is suggested that current design guideline should provides not only the minimum radius but also the management of road alignment design to minimize the gap between the design speed and operating speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.300-309
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• 2016

Curved beams are increasingly used in buildings, vehicles, ships, and aircraft, which has resulted in considerable effort towards developing an accurate method for analyzing the dynamic behavior of such structures. The stability behavior of elastic curved beams has been the subject of many investigations. Solutions to the relevant differential equations have traditionally been obtained by the standard finite difference or finite element methods. However, these techniques require a great deal of computer time for a large number of discrete nodes with conditions of complex geometry and loading. One efficient procedure for the solution of partial differential equations is the differential quadrature method (DQM). This method has been applied to many cases to overcome the difficulties of complex algorithms and high storage requirements for complex geometry and loading conditions. Out-of-plane buckling of curved beams with rotatory inertia were analyzed using DQM under uniformly distributed radial loads. Critical loads were calculated for the member with various parameter ratios, boundary conditions, and opening angles. The results were compared with exact results from other methods for available cases. The DQM used only a limited number of grid points and shows very good agreement with the exact results (less than 0.3% error). New results according to diverse variation are also suggested, which show important roles in the buckling behavior of curved beams and can be used for comparisons with other numerical solutions or experimental test data.