• Journal of Korean Institute of Industrial Engineers
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• v.38 no.2
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• pp.125-132
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• 2012

In this study, we consider zone-based registration (ZBR). In the ZBR, when a mobile station (MS) enters a new location area (LA), it registers its location. Among various types of ZBR, we focus on two zone-based registration with outgoing call (TZRC) that is an improved version of the two zone-based registration (TZR). In the TZR, an MS can store two LAs that it registers recently not to register when it crosses two LAs stored already. In general, TZR has better performance than single zone-based registration (SZR). However, since the TZR may increase paging cost, TZRC was proposed to decrease paging cost. Mathematical analysis is performed to obtain the exact performance of SZR, TZR, TZRC. From the numerical results for various circumstances, it is shown that TZRC outperforms TZR and SZR in most cases.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.172-180
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• 2008

Many strategies have been proposed to reduce mobility management cost. Among them, in this paper, we study three schemes of zone-based registrationthat have been adopted by most of mobile systems. These special schemes are referred to as the single-zone-based registration (SZR), the two-zone-based registration (TZR) and the two-zone-based registration with outgoing call (TZRC) respectively. We propose a mathematical model to evaluate the performance of TZRC in order to compare with those of SZR and TZR. Numerical results show that TZRC outperforms not only SZR but also TZR in most cases.

• Journal of the Korean Ceramic Society
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• v.38 no.2
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• pp.166-172
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• 2001

고 인성의 Y-TZP 세라믹스에 0.5$\mu\textrm{m}$, 1$\mu\textrm{m}$, 3$\mu\textrm{m}$ 알루미나를 20 vol% 분산시킨 후 입자크기에 따른 미세구조와 파괴인성 변화를 관찰하였다. 알루미나 분산 지르코니아 세라믹스는 98% 이상의 높은 밀도를 나타내었으며, 알루미나 입자가 균질하게 분산된 치말한 미세구조를 나타내었다. 알루미나를 분산시킨 시편에서는 순수 지르코니아에 비하면 파괴인성이 증가하였고, 분산시킨 알루미나 입자크기가 증가함에 따라 파괴인성이 증가하였다. 파괴인성은 분산된 알루미나 입자크기가 3$\mu\textrm{m}$일 때 3Y-TZP는 8.6 MPa.m$^{1}$2/에서 12.5 MPa.m$^{1}$2/로, 2Y-TZP는 13.5 MPa.m$^{1}$2/에서 18.9 MPa.m$^{1}$2/로 각각 증가하였는데, 이는 파괴시 알루미나 입자에 의한 균열편향 효과로 인하여 균열길이가 증가하기 때문이었다.