• The Korean Journal of Applied Statistics
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• v.19 no.3
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• pp.447-460
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• 2006

This paper develops a multiple comparison method for finding an optimal ordering of K geometric means of exponential parameters. This is based on the paired comparison experimental arrangement whose results can naturally be represented by a completely oriented graph. Introducing posterior preference probabilities and stochastic transitivity conditions to the graph, we obtain a new graphical model that yields criteria for the optimal ordering in the multiple comparison. Necessary theories involved in the method and some computational aspects are provided. Some numerical examples are given to illustrate the efficiency of the suggested method.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.332-339
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• 2013

The network nodes in a tactical network moves continuously and due to the physical and electronic obstacles, the connections are not always available. Due to the frequent disconnections, it is hard to discover the path among the nodes in a DTN. According to PROPHET(Probabilistic Routing Protocol using History of Encounters and Transitivity), one of the most well-known DTN routing protocols, a DTN node determines whom to forward a packet according to the packet delivery probability. From the viewpoint of a node, the packet delivery probability of another node is degraded while the nodes are disconnected whereas it is improved when they encounter. In this paper, we enhance the algorithm estimating the packet probability by considering the encounter count as an additional parameter. Our algorithm prefers the node that encounters the destination more frequently in selecting the next hop toward the destination. We evaluated the performance of our algorithm by simulating military operations using a DTN-dedicated simulator. Through the simulations, we show that our proposed algorithm achieve higher packet delivery ratio with similar overhead compared with PROPHET.

• Journal of Computing Science and Engineering
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• v.6 no.3
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• pp.207-218
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• 2012

In recent years, the skyline query paradigm has been established as a reliable method for database query personalization. While early efficiency problems have been solved by sophisticated algorithms and advanced indexing, new challenges in skyline retrieval effectiveness continuously arise. In particular, the rise of the Semantic Web and linked open data leads to personalization issues where skyline queries cannot be applied easily. We addressed the special challenges presented by linked open data in previous work; and now further extend this work, with a heuristic workflow to boost efficiency. This is necessary; because the new view on linked open data dominance has serious implications for the efficiency of the actual skyline computation, since transitivity of the dominance relationships is no longer granted. Therefore, our contributions in this paper can be summarized as: we present an intuitive skyline query paradigm to deal with linked open data; we provide an effective dominance definition, and establish its theoretical properties; we develop innovative skyline algorithms to deal with the resulting challenges; and we design efficient heuristics for the case of predicate equivalences that may often happen in linked open data. We extensively evaluate our new algorithms with respect to performance, and the enriched skyline semantics.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2218-2224
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• 2016

Opportunistic routing is designed for an environment where there is no stable end-to-end routing path between source node and destination node, and messages are forwarded via intermittent contacts between nodes and routed using a store-carry-forward mechanism. In this paper, we consider PRoPHET(Probabilistic Routing Protocol using History of Encounters and Transitivity) protocol as a base opportunistic routing protocol and propose an efficient context-aware opportunistic routing protocol by using the context information of delivery predictability and node type, e.g., pedestrian, car, and tram. In the proposed protocol, the node types of sending node and receiving node are checked. Then, if either sending node or receiving node is tram, messages are forwarded by comparing the delivery predictability of receiving node with predefined delivery predictability thresholds depending on the combination of sending node and receiving node types. Otherwise, messages are forwarded if the delivery predictability of receiving node is higher than that of sending node, as defined in PRoPHET protocol. Finally, we analyze the performance of the proposed protocol from the aspect of delivery ratio, overhead ratio, and delivery latency. Simulation results show that the proposed protocol has better delivery ratio, overhead ratio, and delivery latency than PRoPHET protocol in most of the considered simulation environments.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.11
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• pp.1116-1120
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• 2010

In this paper we present two refined neighbor selection algorithms for recommender systems and also show how the attributes of the items can be used for higher prediction quality. The refined neighbor selection algorithms adopt the transitivity-based neighbor selection method using virtual neighbors and alternate neighbors, respectively. The experimental results show that the recommender systems with the proposed algorithms outperform other systems and they can overcome the large scale dataset problem as well as the first rater problem without deteriorating prediction quality.

• Communications of Mathematical Education
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• v.3
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• pp.229-249
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• 1997

폴리아가 그의 저서 ‘How to Solve It.'에서 주창한 문제 해결의 모형은 이렇게 해석될 수 있다. 곧, 절대 다수의 수학 문제는 조건문 (p${\rightarrow}$q)의 명제 형식으로 분해된다는 것이다. 그리하여 순조롭게 발생되는 문제 해법의 전과정은 아래와 같이 마치 징검다리를 놓듯 추이율(transitivity)을 연거퍼 적용하는(이른바 연추적이라 함) 절차이다. (p: 주어진 정보) ${\rightarrow}$ ${\cdots}$ ${\rightarrow}$ ${\cdots}$ ${\rightarrow}$ (구하는 정보: q) 이것은, 일반적으로, 추이율이 성립하는 모든 관계(relation)의 연추적 확인 과정으로 확장될 수 있다. 요컨대 항진식 (p${\rightarrow}$r) ${\wedge}$ (r${\rightarrow}$q) ${\rightarrow}$ (p${\rightarrow}$q)의 보장 아래 관계의 추이율 xRz ${\wedge}$ zRy ${\rightarrow}$ xRy 로 연결되는 온갖 경로를 포괄한다. 이상과 같이 정식화되는 이 도식의 한계와 효용은 (1) 모든 문제가 조건문의 형태를 갖추고 있는 것은 아니며, (2) 조건문 형식의 문제라도 해법이 반드시 연추적으로 발생되는 법도 아니고, (3) 더구나 이것이 해법 발생의 만능 열쇠는 아닐뿐더러, (4) 발상을 촉진하는 데는 교육공학적으로 더 정교한 배려가 필요하므로, (5) 초보 단계에서 행동 수정을 위한 치유 목적으로 사용됨이 바람직하다.

• Asia pacific journal of information systems
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• v.29 no.3
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• pp.382-406
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• 2019

We study the antecedents to tie formation on an (Facebook-like) enterprise social media platform implemented to support cross-boundary connections. Research has produced mixed findings regarding the role of social media in cultivating bridging vs. closed networks. We examine the tie formation patterns of 1,386 enterprise social media users over a two-year period. Specifically, we observe who became (or chose not s become) "friends" with whom at the dyadic level and relate the decisions to various mechanisms that affect one's network to expand, constrain, or bridge. Using logistic and OLS regressions, we find that users tend to form ties via reciprocity and transitivity (with friends of friends), both of which help expand one's network. We also find strong networking tendency toward functional and hierarchical homophily (same business unit and same rank, respectively), which is likely to constrain one's network (closed network structure). We find that one's participation in various online interest groups is likely to open one's network (bridging network structure) while no evidence found for preferential attachment. Overall, we find that enterprise social media offers features, some of which are likely to foster bridging while others foster closed networks via different mechanisms.

• Journal of KIISE:Software and Applications
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• v.27 no.5
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• pp.551-562
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• 2000

Content-based image retrieval system retrieves an image from a database using visual features. Among approaches to express visual aspects in queries, 'query by sketch' is most convenient and expressive. However, every 'query by sketch' system has the query imperfectness problem. GContent-based image retrieval system retrieves an image from a database using visual features. Among approaches to express visual aspects in queries, 'query by sketch' is most convenient and expressive. However, every 'query by sketch' system has the query imperfectness problem. Generally, the query image produced by a user is different from the intended target image. To overcome this problem, many image retrieval systems use the spatial relationships of the objects, instead of pixel coordinates of the objects. In this paper, a query-converting algorithm for an image retrieval system, which uses the spatial relationship of every two objects as an image feature, is proposed. The proposed algorithm converts the query image into a graph that has the minimum number of edges, by eliminating every transitive edge. Since each edge in the graph represents the spatial relationship of two objects, the elimination of unnecessary edges makes the retrieval process more efficient. Experimental results show that the proposed algorithm leads the smaller number of comparison in searching process as compared with other algorithms that do not guarantee the minimum number of edges.

• The Journal of the Korea Contents Association
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• v.20 no.4
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• pp.658-672
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• 2020

The purpose of this study is to empirically compare statistical models for pre-service teachers' help networks. We identified similarities and differences based on the results of the binary and valued ERGM. Research questions are as follows: First, what are the similarities of factors influencing the binary/valued help network for pre-service teachers? Second, what are differences of factors influencing the binary/valued help network for pre-service teachers? We measured 42 pre-service teachers with focus on their help and friend networks, happiness, and personal characteristics. Results indicated that, first, the similar factors influencing the binary and valued help network of pre-service teachers were local dependencies (reciprocity, transitivity), similarity (major, gender), activity (early childhood education, negative emotion), popularity (early childhood education) and multiplicity (friend network). Second, the difference between factors affecting pre-service teacher's binary and valued help network was the effect of activity (physical education) and popularity (GPA, negative emotion). Based on these findings, we presented implications.

• Plant Biotechnology Reports
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• v.4 no.3
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• pp.185-192
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• 2010

The Arabidopsis ${\omega}$-3 fatty acid desaturase (AtFAD7) catalyzes the synthesis of trienoic fatty acids (TA). A transgenic tobacco line, T15, was produced by a sense AtFAD7 construct and showed a cosuppression-like phenotype, namely extremely low TA levels. The sequence similarity between AtFAD7 and a tobacco ortholog gene, NtFAD7, was moderate (about 69%) in the coding sequences. AtFAD7 siRNAs accumulated at a high level, and both AtFAD7 and NtFAD7 mRNAs are degraded in T15 plants. The low-TA phenotype in T15 was dependent on a tobacco RNA-dependent RNA polymerase6 (NtRDR6). We also produced tobacco RNAi plants targeting AtFAD7 gene sequences. The AtFAD7 siRNA level was trace, which was associated with a slight reduction in leaf TA level. Unexpectedly, this RNAi plant showed an increased NtFAD7 transcript level. To investigate the effect of translational inhibition on stability of the NtFAD7 mRNAs, leaves of the wild-type tobacco plants were treated with a translational inhibitor, cycloheximide. The level of NtFAD7 mRNAs significantly increased after cycloheximde treatment. These results suggest that the translational inhibition by low levels of AtFAD7 siRNAs or by cycloheximide increased stability of NtFAD7 mRNA. The degree of silencing by an RNAi construct targeting the AtFAD7 gene was increased by co-existence of the AtFAD7 transgene, where NtRDR6-dependent amplification of siRNAs occurred. These results indicate that NtRDR6 can emphasize silencing effects in both cosuppression and RNAi.