• The KIPS Transactions:PartA
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• v.8A no.1
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• pp.36-41
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• 2001

In this paper, we first design an parallel quadratic sieve algorithm for factoring method. We then present parallel factoring algorithm for factoring a large odd integer by repeatedly using the parallel quadratic sieve algorithm based on the divide-and-conquer strategy on SIMD machines with DMM. We show that this algorithm is optimal in view of the product of time and processor numbers.

• Journal of the Korea Safety Management & Science
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• v.17 no.4
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• pp.381-396
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• 2015

The study proposes multiple TRIZ contradiction solution strategies for addressing PC (Physical Contradiction) and TC (Technical Contradiction) by implementing TRIZ cause-and-effect tree. The problem associated with TC of the ends is solved by PC of means which employs a causal relationship between causes and effects. The TRIZ contradiction solution strategies demonstrated in this research are classified into 3 types of combined strategy as follows: 1. To-Be PC and AS-Is PC, 2.To-Be PC and As-Is TC, 3.As-Is PC and To-Be TC. The combined strategy of To-Be PC and As-Is PC is similar to a divide-and-conquer technique. This strategy adopts parallel strategies using 4 separation principles in time, in space, between parts and the whole, and upon condition of two reversed-PCs. Moreover, its application elucidates the conflict relationship of two TCs from the study. The integrated 4 separation principles and 40 inventive principles present an effective synergy effect from the combination, and further addresses the problems in the TRIZ contradiction resolution strategies. Combined strategy of To-Be PC and As-Is TC implements the 40 inventive principles that To-Be PC of the means resolves the As-Is TC of the ends. Combined strategy of As-Is PC and To-Be TC also uses inventive principles to the As-Is PC of the means to solve the To-Be TC of the ends. In addition, propositional and logical relationship of necessary and sufficient conditions between TC and PC is used to support the validity of 3 TRIZ contradiction solution strategies. In addition, 3 other strategies of necessary and sufficient conditions validate the contraposition relationship of the truth table. This study discusses TRIZ case studies from National Quality Circle Contest from the years between 2011 and 2014 to provide the usage guidelines of TRIZ contradiction solutions for quality purposes. Examining analysis from the case studies and investigating combined strategies allows the users to obtain comprehensive understanding.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.1
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• pp.147-169
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• 2024

In pace with the development of network technology at lightning speed, social networks have been extensively applied in our lives. However, as social networks retain a large number of users' sensitive information, the openness of this information makes social networks vulnerable to attacks by malicious attackers. To preserve the link privacy of individuals in social networks, an uncertain graph method based on node random response is devised, which satisfies differential privacy while maintaining expected data utility. In this method, to achieve privacy preserving, the random response is applied on nodes to achieve edge modification on an original graph and node differential privacy is introduced to inject uncertainty on the edges. Simultaneously, to keep data utility, a divide and conquer strategy is adopted to decompose the original graph into many sub-graphs and each sub-graph is dealt with separately. In particular, only some larger sub-graphs selected by the exponent mechanism are modified, which further reduces the perturbation to the original graph. The presented method is proven to satisfy differential privacy. The performances of experiments demonstrate that this uncertain graph method can effectively provide a strict privacy guarantee and maintain data utility.

• The KIPS Transactions:PartB
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• v.14B no.6
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• pp.413-422
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• 2007

This paper addresses a new technique for constructing surface model from a set of wire-frame contours. The most difficult problem of this technique, called contour triangulation, arises when there are many branches on the surface, and causes lots of ambiguities in surface definition process. In this paper, the branching problem is reduced as the surface reconstruction from a set of virtual belts and virtual canyons. To tile the virtual belts, a divide-and-conquer strategy based tiling technique, called the BPA algorithm, is adopted. The virtual canyons are covered naturally by an iterative convex removal algorithm with addition of a center vertex for each branching surface. Compared with most of the previous works reducing the multiple branching problem into a set of tiling problems between contours, our method can handle the problem more easily by transforming it into more simple topology, the virtual belt and the virtual canyon. Furthermore, the proposed method does not involve any set of complicated criteria, and provides a simple and robust algorithm for surface triangulation. The result shows that our method works well even though there are many complicated branches in the object.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.139-145
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• 2012

Generally, Quicksort selects the pivot from leftmost, rightmost, middle, or random location in the array. This paper suggests Quicksort using middle range pivot $P_0$ and continually divides into 2. This method searches the minimum value $L$ and maximum value $H$ in the length n of list $A$. Then compute the initial pivot key $P_0=(H+L)/2$ and swaps $a[i]{\geq}P_0$,$a[j]<P_0$ until $i$=$j$ or $i$>$j$. After the swap, the length of list $A_0$ separates in two lists $a[1]{\leq}A_1{\leq}a[j]$ and $a[i]{\leq}A_2{\leq}a[n]$ and the pivot values are selected by $P_1=P_0/2$, $P_2=P_0+P_1$. This process repeated until the length of partial list is two. At the length of list is two and $a$[1]>$a$[2], swaps as $a[1]{\leftrightarrow}a[2]$. This method is simpler pivot key process than Quicksort and improved the worst-case computational complexity $O(n^2)$ to $O(n{\log}n)$.