• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.121-128
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• 2005

This paper describes the requested IP assignment and authentication problem for wireless internet service of visited ISP subscriber on GPRS network, and proposes to use RADIUS authentication and accounting server for these problems. In this paper, we also define signals between GGSN and RADIUS, and between RADIUS authentication server and accounting sever for IP management and wireless internet service.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.97-103
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• 2008

Determination of stress-strain relationship in torsional tests is complicated due to nonuniform stress-strain variation occurring linearly with the radius in a soil specimen in torsion. The equivalent radius approach is adequate when calculating strain at low to intermediate strains, however, the approach is less accurate when performing the test at higher strain levels. The modified equivalent radius approach was developed to account for the problem more precisely. This approach was extended to generate the plots of equivalent radius ratio versus strain using modified hyperbolic and Ramberg-Osgood models. Results showed the effects of soil nonlinearity on the equivalent radius ratio curves were observed. Curve fitting was also performed to find the stress-strain relationship by fitting the theoretical torque-rotation relationship to measured torque-rotation relationship.

• Korean Journal of Mathematics
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• v.31 no.4
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• pp.433-444
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• 2023

Given a function f analytic in open disk centred at origin of radius unity and satisfying the condition |f(z)/g(z) - 1| < 1 for a analytic function g with certain prescribed conditions in the unit disk, radii constants R are determined for the values of Rzf'(Rz)/f(Rz) to lie inside the domain enclosed by the curve |w² - 1| = 1 (lemniscate of Bernoulli). This, in turn, provides a partial solution to the conjectures and problems for determination of sharp bounds R for such functions f.

• Bulletin of the Korean Mathematical Society
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• v.22 no.1
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• pp.31-36
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• 1985

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.629-634
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• 2000

Generally, the accuracy of motion control systems is strongly influenced by both the mechanical characteristics and servo characteristics of feed drive systems. In the fed drive systems of machine tools that consist of mechanical parts and electrical parts, a torsional vibration is often generated because of its elastic elements in torque transmission. Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed drive system. In this paper, based on the simplifies feed drive system model, radius errors due to position gain mismatch and servo response characteristic have been developed and an optimal criterion for tuning the gain of speed controller is discussed. The proportional and integral parameter gain of the feed drive controller are optimal design variables for the gain tuning of PI speed controller. Through the optimization problem formulation, both proportional and integral parameter are optimally tuned so as to compensate the radius errors by using the genetic algorithm. As a result, higher performance on circular profile tests has been achieved than the one with standard parameters.

• Geomechanics and Engineering
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• v.21 no.3
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• pp.289-300
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• 2020

Estimating the damage induced by an explosion around a blast hole has always been a challenging issue in geotechnical engineering. It is difficult to determine an exact dimension for damage zone since many parameters are involved in the formation of failures, and there are some uncertainties lying in these parameters. Thus, the present study adopted a probabilistic approach towards this problem. First, a reliability model of the problem was established and the failure probability of induced damage was calculated. Then, the corresponding exceedance risk curve was developed indicating the relation between the failure probability and the cracked zone radius. The obtained risk curve indicated that the failure probability drops dramatically by increasing the cracked zone radius so that the probability of exceedance for any crack length greater than 4.5 m is less than 5%. Moreover, the effect of each parameter involved in the probability of failure, including blast hole radius, explosive density, detonation velocity, and tensile strength of the rock, was evaluated by using a sensitivity analysis. Finally, the impact of the decoupling ratio on the reduction of failures was investigated and the location of its maximum influence was demonstrated around the blast point.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.5
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• pp.567-577
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• 2003

We usually applied PPP CHAP (Point-to-Point Protocol Challenge Handshake Authentication Protocol) when the visited ISP subscriber accesses to authentication server in own home ISP network and IP Assignment for remote Internet service. But PPP CHAP doesn't support in case of visited ISP subscriber in GPRS network accesses to authentication server in own home ISP network for wireless Internet service. We suggest solution this problem with PPP CHAP improvement. For this we propose the modified PPP CHAP message format, PCO Message format at MT, and interworking message and format between GGSN and RADIUS in home ISP network for wireless internet service of mobile ISP subscriber at GPRS network in this paper. We also show authentication results when visited mobile ISP subscriber via PPP CHAP at GPRS network accesses the RADIUS server in home ISP network.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.125-133
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• 2008

Achieving consistent geometric design is an important goal in highway design to ensure obtaining safe, economical and smooth traffic operation. Most evaluation of consistency is based on 'speed change' in speed profile. According to literature, the speed depends on geometric elements, speed on tangent section prior to a curve, and background around roads. Especially, the radius is the most main element mentioned in various literature. Therefore, this paper shows two ways of calculating horizontal radius on real road, that is, three-dimensional road. First of all, the radius of horizontal curve is calculated based on physical method. The calculated radius contains not only superelevation but also longitudinal grade while the current minimum radius is calculated by considering superelevation and side friction according to the point-mass equation. Secondly, the problem of composed curves with distorted appearance by overlaying sag or crest vertical alignment has been known. To quantify the extent of distortion effects, the method of calculation of real seen so called 'Perspective Radius' is developed. The paper presents the perspective radius and recommended perspective radius.

• Archives of Reconstructive Microsurgery
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• v.16 no.2
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• pp.125-132
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• 2007

Introduction: Ulna is nearly equal to radius in function and bony architecture and strength in forearm. But in lower extremity, fibula is 1/5 of tibia in anatomic and functional point so we can find fibula transposition is commonly used in defect of tibia. We cannot find other article about segmental forearm bone transposition in man. The purpose of this study was to report our clinical and functional result of undergoing segmented transposition of ipsilateral ulna with its own vascular supply in defect of radius in 6 cases. Material and method: From June 1994 to October 2007, 7 segmented bone transpositional grafts in forearm were performed in Kyung Hee Medical Center. The distribution of age was from 20 years old to 73 years old. There was male in 6 cases and female in 1 case. The causes of operation were giant cell tumor in 1 case and traumatic origin in 6 cases; it was nonunion in 2 cases and fracture with severe comminution in 4 cases. Ipsilaterally segmented ulna keeping its own vascular supply was transported to defect of radius in severe traumatic patients and one patient whose tumor in radius had been excised. Transported ulna was fixed to proximal and distal radius remnants by plate and screw. In one case with giant cell tumor, transported ulna was connected to radius across wrist joint as wrist joint fusion. Joint preserving procedures were performed in 6 cases with crushing injury of radius. Results: We could obtain solid bony union in all cases and good functional results. The disadvantage was relative shortening of forearm, but we could overcome this problem. Conclusion: We think that ipsilateral segmented ulna transposition keeping its own vascular supply to radius can be perfomed with one of procedures in cases with wide defect in radius.

• Proceedings of the KWS Conference
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• v.43
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• pp.275-277
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• 2004

Fictitious notch radius approach is based on the Neuter's microstructural support hypothesis which assumes that fatigue crack is governed by highly stressed volume of the material right on the weld toe area rather than the surface stress at a pin point of weld toe area. Variety of successes have been achieved in applying this methodology to the fatigue of welded joint, hence, it became one of recommended design procedure in IIW's recommendation as well as many ship classification societies. 1mm fictitious notch radius approach was applied to the various fatigue problems of welded joints in this study covering the effect of weld size, notch stress calculation for 3D geometry and low cycle fatigue problem. It was found that fictitious notch radius approach fumed out to be very effective and accurate in dealing with fatigue strength of welded joint.