• The Transactions of the Korea Information Processing Society
• /
• v.3 no.7
• /
• pp.1707-1718
• /
• 1996

Given a signal net N=s, 1,...,n to be the set of nodes, with s the source and the remaining nodes sinks, an MRDPT (minimum-cost rectilinear Steiner distance -preserving tree) has the property that the length of every source to sink path is equal to the rectilinear distance between the source and sink. The minimum- cost rectilinear Steiner distance-preserving tree minimizes the total wore length while maintaining minimal source to sink length. Recently, some heuristic algorithms have been proposed for the problem offending the MRDPT. In this paper, we investigate an optimal structure on the MRDPT and present a theoretical breakthrough which shows that the min-cost flow formulation leads to an efficient O(n2logm)2) time algorithm. A more practical extension is also in vestigated along with interesting open problems.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.9
• /
• pp.17-26
• /
• 2011

Many types of services appear in a ubiquitous environment promulgated by the evolution of web service technology with the advances in wireless network technologies and mobile computing devices. These services differ according to their location environments, such as home, office, airport, and exhibition. It is required that a different set of services dynamically drops into the mobile user's device depending on their context and the distributed localized services are efficiently managed to seamlessly provide these localized services to the user. This paper proposes an Autonomic Service Composition System (ASCS) to provide useful services to the user with minimal or no effort for service selection. ASCS seamlessly installs the programs of localized services in the user's mobile device. It automatically provides localized services to users that are in the local service zone. Also ASCS can manage distributed localized services remotely and efficiently. ASCS is composed of a Remote Manager, Service Gateway, and Mobile Device. The prototype implementation uses 802.11b Wireless Network and Bundles using the OSGi Framework.

• Clinics in Shoulder and Elbow
• /
• v.9 no.1
• /
• pp.96-104
• /
• 2006

Purpose: To evaluate and compare the results of children with displaced supracondylar fractures of humerus treated with open reduction and pinning with closed reduction and pinning. Materials and Methods: From March 2002, we treated 17 patients with completely displaced supracondylar fractures under the age of 7 with a minimal follow up period of 6 months. 9 patients were treated with closed reduction and pinning and 8 patients were treated with open reduction and pinning. The clinical results were evaluated with Flynn's criteria. Time to bone union was also analyzed for these two set of patients. Results: The group treated with open reduction had 6 excellent and 2 good results for change in carrying angles, 5 excellent, 2 good and 1 fair results for motion loss evaluated by Flynn's criteria. The average time to bony union for this group was 5.8 weeks. The group treated with closed reduction had 6 excellent, 2 good, and 1 fair results for change in carrying angles and 7 excellent, 1 good and 1 fair results for motion loss. The average time to bony uinon for this group was 3.7 weeks. Conclusion: In treating completely displaced supracondylar fractures of humerus in children, the closed reduction method and open reduction method all showed good results. But the operation time, duration of hospital stay and time to union was somewhat shorter for the patients treated with closed redution and pinning.

• Journal of the Korean Mathematical Society
• /
• v.58 no.3
• /
• pp.643-702
• /
• 2021

Fix ℤ/2 is the prime field of two elements and write 𝒜₂ for the mod 2 Steenrod algebra. Denote by GL_d := GL(d, ℤ/2) the general linear group of rank d over ℤ/2 and by ${\mathfrak{P}}_d$ the polynomial algebra ℤ/2[x₁, x₂, …, x_d] as a connected unstable 𝒜₂-module on d generators of degree one. We study the Peterson "hit problem" of finding the minimal set of 𝒜₂-generators for ${\mathfrak{P}}_d$. Equivalently, we need to determine a basis for the ℤ/2-vector space $$Q{\mathfrak{P}}_d:={\mathbb{Z}}/2{\otimes}_{\mathcal{A}_2}\;{\mathfrak{P}}_d{\sim_=}{\mathfrak{P}}_d/{\mathcal{A}}^+_2{\mathfrak{P}}_d$$ in each degree n ≥ 1. Note that this space is a representation of GL_d over ℤ/2. The problem for d = 5 is not yet completely solved, and unknown in general. In this work, we give an explicit solution to the hit problem of five variables in the generic degree n = r(2^t - 1) + 2^ts with r = d = 5, s = 8 and t an arbitrary non-negative integer. An application of this study to the cases t = 0 and t = 1 shows that the Singer algebraic transfer of rank 5 is an isomorphism in the bidegrees (5, 5 + (13.2⁰ - 5)) and (5, 5 + (13.2¹ - 5)). Moreover, the result when t ≥ 2 was also discussed. Here, the Singer transfer of rank d is a ℤ/2-algebra homomorphism from GL_d-coinvariants of certain subspaces of $Q{\mathfrak{P}}_d$ to the cohomology groups of the Steenrod algebra, $Ext^{d,d+*}_{\mathcal{A}_2}$ (ℤ/2, ℤ/2). It is one of the useful tools for studying these mysterious Ext groups.