• Honam Mathematical Journal
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• v.39 no.4
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• pp.515-525
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• 2017

In this paper, we study planar normal section curves. We have interpreted curvatures of normal section curves. On the other hand we have investigated sufficient and necessary conditions for a normal section curve to be biharmonic.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.2
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• pp.77-90
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• 1994

Curve-net interpolation surface is one of the most popular method in engineering design. Therefore it is supported with many commercial CAD/CAM system. However, construction algorithm of curve-net interpolation surfaces is rarely opened to the public because of its copy-right. In this paper we establish a construction algorithm of curve-net interpolation surface so called sweeping surface which especially concentrates on trajectory of cross-section curve. We also show the method which can construct sweeping surfaces as NURB or Bezier mathematical models. Surfaces having the form of standard mathematical models are very useful for the application of joining, trimming, blending etc. The proposed surface interpolation scheme consists of four steps; (1) preparation of guide curves and section curves, (2) remeshing guide curves and section curves, (3) blending section curves after deformation, and (4) determination of control points for sweeping surface using gordon method. The proposed method guarantee $G^1$-continuety, and construct the surface salifying given section curves and trajectory of section curves.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.309-314
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• 2003

A vertical curve should be installed in straight section. In case, it be installed on horizontal curved section, safety factor go down. In this study, it is calculated that the deficiency of cant about vertical curve radius on horizontal curved section. The result of this study will be used on planning the tack layout of railroad and design the track construction.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.23-29
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• 2008

This research proposes two sub-models and one integrated model for the classification of safety in curve section of road, where the fatal-rate is relatively higher in accidents. The first sub-model calculates the accident-rate by safety-index that is based on the road geometries. The second decides the safety of curve section by the speed difference between before and in the curve. Finally, the integrated model of two sub-modules can classify the safety of curve section of road.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1301-1309
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• 2008

The curved portion fur each section running safety evaluation interpretation according to the track condition for improving the curved portion passage rate of a vehicle by using the multibody analysis model of the Saemaeul train was carried out. As a result, The excess of cant reaches the bad effect to the running safety in case the radius of curvature is small. In case the radius of curvature was large, we could confirm that the deficiency of cant reached the bad effect to the running safety. In the curved portion, the circular curve section most badly showed the running safety. The deficiency of curve length reaches the bad to the running safety. In the curved portion, the circular curve section most badly showed the running safety. Therefore the track condition(cant, transition curve length, etc) can reach the bad effect to the running safety of a vehicle, the exact design is required.

• Structural Engineering and Mechanics
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• v.68 no.6
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• pp.713-720
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• 2018

In this paper a new numerical method to determine the elastic curve of the simply supported beams of variable cross-section is demonstrated. In general case it needs to solve linear or small nonlinear second order differential equations with prescribed boundary conditions. For numerical solution the initial values of the slope and the deflection of the end cross-section of the beam is necessary. For obtaining the initial values a lively procedure is developed: it is a special application of the shooting method because boundary value problems can be transformed into initial value problems. As a result of these transformations the initial values of the differential equations are obtained with high accuracy. Procedure is applied for calculating of elastic curve of a simply supported beam of variable cross-section. Results of these numerical procedures, analytical solution of the linearized version and finite element method are compared. It is proved that the suggested procedure yields technically accurate results.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1614-1621
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• 2008

I accomplished a curve section traveling safety assessment analysis followed with railway condition for elevation of a curve passage speed of train utilizing trail analysis model. As a result, we confirmed that excess cant influence in badly traveling safety of train followed with cant change and cant shortage influence in badly traveling safety in case of large a curve radius and traveling safety of originally a curve section is most wrong. Also we confirmed that shortage of relief a curve length influence in badly traveling safety followed with change of relief a curve length.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.84-88
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• 2010

The main point of this study is to find ways to prevent accidents at complex linear sections in advance by improving geometric structure elements that can be considered from the designing stage. Complex linear roads are consisted of sections where straight sections connect with curved sections or sections where curved sections connect with curved sections with relatively high possibility of accidents and accidents can be reduced through improving designing elements in these sections. Therefore, this study aims to develop accident forecasting model in complex linear roads and to clarify major elements affecting traffic accidents. The results of analysis showed that the groups are divided into a group less than 355m based on curve radius of 355m, a group whose curve radius exceeds 355m and a group whose incline exceeds -0.79 and a group whose curve radius is below 355m and incline exceeds -0.79 for straight section + curved section, and for curved section + curved section, it is divided into a group whose first curved section is less than 410m based on curve radius of 410m and the first curve is turning right and a group exceeding 410m and the first curve is turning left. The major variables common in 2 models are front curve radius and curve types(left, right), road surfaces, weather.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.1
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• pp.1-6
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• 1993

The cant has setted up wrong in a part of railway curve sections, occasionally confusion occur in curve maintenance. In this study, it is suggest effective maintenance method in railway curve section about the radius of curvature, cant successive diminution length, according to the investigation of cant value, compare and analysis with straight decrease in order theory.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.109-130
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• 2002

The purpose of this paper was to make a comparative analysis for the difference of the various kinematic variation which is occurred in the each situation when pitchers throw a straight and a curve ball. Four pitchers, who are two national team players and two high level pitchers, were selected among the right over hand pitchers of D university in the Busan for this paper. The data were analyzed by using 3D equipment. The results of the analysis which was about the elapsed time of the pitching, the movement of the body center-point, the highest height of the left knee, stride length, knee joint angle, shoulder joint angle, elbow joint angle and wrist joint angle in the each section(ST, LKU, HBP, LCF, MCP, BRP) were as follows : 1. Pitching time in the each section and step in the pitching for straight and curve ball was similar. The total elapsed time of the straight and curve ball was 1.78${\pm}$0.07sec and 1.77${\pm}$0.11sec in the order. 2. The position change of the body center to the Z(above below) direction did not show significant difference in the each situation of the section and step between pitching for the straight and curve ball. 3. Height of the left knee did not show significant difference as 125.38${\pm}$11.85cm and 124.95${\pm}$11.63m in the each pitching motion for straight and curve ball. The rate(%H) between height and stride length showed 68.42${\pm}$5.53(%H), 68.40${\pm}$5.45(%H) in the each pitching motion. 4. Pitching for curve ball showed longer stride length than pitching for straight ball that as the stride length was 140.35${\pm}$4.96cm and 144.8${\pm}$1.69cm. The rate(%H) between height and stride length showed 76.9${\pm}$3.77(%H), 79.39${\pm}$2.23(%H) in the each pitching motion. 5. Left knee joint angle did not show significant difference in the ST, LKU and HBP section in the each pitching motion. However, it was shown that knee joint angle was flexed much more in the LFC, MCP and BRP section in the pitching for curve ball. 6. Right shoulder joint angle did not show significant difference in the ST, LKU and HSP section. However, when pitches threw a curve ball in the LKU section. In the LFC section, the right shoulder joint angle was extended much more in the pitching for curve ball, and the angle was extended much in the MCP and BRP section in the pitching for curve ball than straight ball. 7. Right elbow joint angle did not show significant difference in the ST, LKU and HRP section in the two pitching motion. The angle had more flexion in the LFC and MCP section in the pitching for curve ball than the pitching for straight ball. The angle in the each pitching motion for straight ball and curve ball were extended by a narrow margin in the BRP section. 8. Right wrist joint angle was extended much more in the LFC and MCP section in the pitching for curve ball. In the BRP section, the angle was extended much more in the pitching for straight ball than curve ball.