• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.5C
• /
• pp.399-410
• /
• 2002

Web cache, which is functionally another word of proxy server, is located between client and server. Web cache has a limited storage area although it has broad bandwidth between client and proxy server, which are usually connected through LAN. Because of limited storage capacity, existing objects in web cache can be deleted for new objects by some rules called replacement algorithm. Hit rate and byte-hit rate are general metrics to evaluate replacement algorithms. Most of the replacement algorithms do satisfy only one metric, or sometimes none of them. In this paper, we propose two replacement algorithms to achieve both high hit rate and byte-hit rate with great satisfaction. In the first algorithm, the cache is appropriately partitioned according to file types as a basic model. In the second algorithm, the cache is composed of two levels; the upper level cache is managed by the basic algorithm, but the lower level is collectively used for all types of files as a shared area. To show the performance of the proposed algorithms, we evaluate hit rate and byte-hit rate of the proposed replacement algorithms using the trace driven simulation.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.2
• /
• pp.335-344
• /
• 2020

This study compared the structures and changes of help network between pre-service secondary teachers and pre-journalists who participated in the class related to network analysis to seek ways to activate a professional learning community. For this study, we used Exponential Random Graph Models (ERGM) based on ties as being interdependent and not conventional regression models requiring assumptions of independence between observations. The analysis subjects were 43 pre-service secondary teachers and 29 pre-journalists who responded both early and late in the help network survey. The main results were as follows. First, full models with network structural terms were better than simple models with no structural terms. Second, the effect of transitivity was not statistically significant in the pre-service secondary teachers' network. However, it was statistically significant in the pre-journalists' network. Third, there were effects of reciprocity, indegree popularity, and outdegree activity in the early help network of pre-service secondary teachers. On the contrary, there were only the positive effects of reciprocity and the negative effect of outdegree activity in the late network. Finally, this study demonstrated the possibility in educational fields' application of network structural effects and provided limitations and directions for future research.

• Korean Journal of Environmental Biology
• /
• v.38 no.4
• /
• pp.650-657
• /
• 2020

We conducted a phylogeographic analysis of Korean endemic Zacco koreanus populations inhabiting the East-flowing river (Gangneung Yeongokcheon; GY, Yangyang Namdaecheon; YN), the Han River (Seomgang; SG, Soksacheon; SS), and the Nakdong River(Gilancheon; GA) using the mitochondrial DNA cytochrome oxidase I (COI) gene (619 bp). Population genetic analysis was further performed to assess the population connectivity for the GY river where there is a large number of human-made artificial weirs with several fishways. The phylogeographic analysis revealed that while the populations of the East-flowing river and those of the Han River formed a monophyletic lineage, the Nakdong River individuals represented a distinct lineage with 3.7-4.2% (mean=4.0%) genetic distance from the other lineages. The population genetic analysis of the GY showed that a mid-stream population harbored relatively higher mitochondrial diversity relative to up- and down-stream populations, and there was no genetic differentiation between these three populations. The latter findings might suggest high genetic connectivity between the populations via genetic flow along the fishways. However, an analysis using faster-evolving genetic markers, such as microsatellites, is needed to confirm the findings of high population connectivity. Our study suggests the possibility of the presence of cryptic species in Z. koreanus in the Nakdong River basin. However, further study with more individual samples as well as additional markers or even more advanced genomic tools is required to test our hypothesis. Ecological or phenotypic analyses should be conducted to test whether the observed Nakdong River lineage represents a different or cryptic species, or simply hidden, but excessive, intraspecific diversity.

• Journal of KIISE:Databases
• /
• v.41 no.4
• /
• pp.226-241
• /
• 2014

LOD(Linked Open Data) is composed of RDF triples which are based on ontologies. They are identified, linked, and accessed under the principles of linked data. Publications of LOD data sets lead to the extension of LOD cloud and ultimately progress to the web of data. However, if ontologically the same things in different LOD data sets are identified by different URIs, it is difficult to figure out their sameness and to provide trustworthy links among them. To solve this problem, we suggest a Trustworthiness Improving Link Evaluation, TILE for short, technique. TILE evaluates links in 4 steps. Step 1 is to consider the inference property of syntactic elements in LOD data set and then generate RDF triples which have existed implicitly. In Step 2, TILE appoints predicates, compares their objects in triples, and then evaluates links between the subjects in the triples. In Step 3, TILE evaluates the predicates' syntactic property at the standpoints of subject description and vocabulary definition and compensates the evaluation results of Step 2. The syntactic elements considered by TILE contain RDFS, OWL, OWL2 which are recommended by W3C. Finally, TILE makes the publisher of LOD data set review the evaluation results and then decide whether to re-evaluate or finalize the links. This leads the publishers' responsibility to be reflected in the trustworthiness of links among the data published.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.23 no.3
• /
• pp.191-195
• /
• 2013

This paper proposes an automatic method for discovering cross-lingual links from English Wikipedia documents to Korean ones in order to increase connectivity among vast web resources. Compared to the existing methods roughly estimating link probability of phrases, candidate anchors are selected from English documents by using various information such as title lists and linking probability extracted from Wikipedia dumps and the results of named-entity recognition, and the anchors are translated into Korean words, and then the most suitable Korean documents with the words are selected as cross-lingual links. The experimental results showed 0.375 of MAP.

• Journal of KIISE:Information Networking
• /
• v.34 no.3
• /
• pp.175-185
• /
• 2007

In IEEE 802.15.4 (Low-Rate Wireless Personal Area Network) specification, a successful reception and validation of a data or MAC command frame can be confirmed with an acknowledgment. However, the specification does not support security for acknowledgment frame; the lack of a MAC covering acknowledgments allows an adversary to forge an acknowledgment for any frame. This paper proposes an identity authentication mechanism at the link layer for acknowledgment frame in IEEE 802.15.4 network. With the proposed mechanism there is only three bits for authentication, which can greatly reduce overhead of device. The encrypted bit stream for identity authentication will be transmitted to device by coordinator within association process. Statistical method and simulation results prove that our mechanism is successful in handling MAC layer attack.

• The Journal of the Korea Contents Association
• /
• v.16 no.8
• /
• pp.160-168
• /
• 2016

The classification and evaluation of cooking that is being published on the internet are presented without scientific criteria based on individual subjective factors. In this paper, we objectified the degree of cooking difficulty based on the information entropy. And we measured the similarity by calculating the common entropy between recipes and constructed a social network based on the recipe similarity. As a result of measuring the cooking difficulty, 'Dongtae Haemul-jjim' (Korean) and 'Vegetarian Lasagna' (Italy) are the most difficult recipes and 'Gochu-jang' (Korean) and 'Tofu steak' (Italy) are the easiest recipes. Through the recipe network, the similarity between Korean and Asian cooking is higher than Western cuisine. We showed a similar recipe to a particular cooking, the group of similar recipes, and reasonable schedule when preparing the menu from the viewpoint of ease of cooking.

• Journal of Intelligence and Information Systems
• /
• v.15 no.1
• /
• pp.87-102
• /
• 2009

With the growth of Web 2.0, lots of services allow yours to post their personal information and useful knowledges on networked information spaces such as blogs and online communities etc. As the services are generalized, recent researches related to social network have gained momentum. However, most social network services do not support machine-processable semantic knowledge, so that the information cannot be shared and reused between different domains. Moreover, as explicit definitions of relationships between individual social entities do not be described, it is difficult to analyze social network for inferring unknown semantic relationships. To overcome these limitations, in this paper, we propose a social network analysis system with personal photographic data up-loaded by virtual community users. By using ontology, an informative connectivity between a face entity extracted from photo data and a person entity which already have social relationships was defined clearly and semantic social links were inferred with domain rules. Then the inferred links were provided to yours as a visualized graph. Based on the graph, more efficient social network analysis was achieved in online community.

• Korean Journal of Environment and Ecology
• /
• v.7 no.1
• /
• pp.22-28
• /
• 1993

Recently, by fast industralization and development without environmental concern, our environment deterioration have being continued rapidly. Therefore, many species is placed on crisis of extinction or was already extincted by habitat destruction. In Minjujisan area, there is a plan to construct the Sport and Leisure Complex by which convert the forest conservancy district to the district of development promotion and district of sighseeing and leisure by Yongdong District. To investigate the avifauna impacts by habitat destruction, bird censuses was carried out before the Sport and Leisure Complex be construct in Minjujisan and Sokgisan area during 4-5 May, 1992 and 16-21 June, 1992. Total 229 birds of 41 species in 23 family of 9 orders were recorded during censuses. Sitta europaea amurensis was the most abundant species and Parus ater amurensis, Phylloscopus borealis xanthodryas, Parus major wladiwostokensis, Parus palustris hellmayri, and Turdus pallidus were dominant species. Accipiter nisus nisosimilis, Accipiter soloenis, and Otus scops stictonotus were found out to the natural monuments in this suvey. Halcyon pileate was observed to a rare bird in this surveyed area. Species diversity of this census was 3.381 which showed slightly higher degree than other surveyed area. The area of Minjujisan, Sokgipong, and Samdopong which have little pollution agent around there and kept away from mankind were approved the heavy avifauna area which have so many bird species. Biogeographically, the Taebaek Mountains was connected with the Sobaek Mountains through this area, therefore it was significant that many animal species could be move to each mountains ranges. The construction plan of the Sport and Leisure Complex in Minjujisan area should be restrain with concern about environmentally destruction by the Muju Resort in Dokyusan National Park which connected to that area have master plan to development the ski slopes for the 1997 Universiad with permission by the Ministry of Environment.

• Korean Journal of Environment and Ecology
• /
• v.10 no.1
• /
• pp.24-38
• /
• 1996

This study was conducted to investigate the Ecobridge district which connects green corridor from Central park to Pulkoksan and to establish of ecological space through analysis of avifauna community, plant community structure. In the results of analysis of avifauna, 3 species 23 individuals(Pica pica, Parus major, [asser montanus) in Ecobridge district, 5 species 37 individuals(Peca pica, Parus major, Passer montanus, Oriolus chinensis, Hirundo rustica) in Central park forest. There were 15 species 72 individuals in Pulkoksan. The plant community structure were classified of three types. As divided types were artificial forest(Pinus rigida, P. koraiensis, etc.) natural forest(Quercus mongolica, Q. serrata, Q. acutissima, Q. spp.) and semi-natural forest, which have shown the successional trends from the artificial forest to Quercus spp. community. The Ecobridge district was used as the space for the passers-by owing to its the simple vegetation. Species diversity was appeared that there was the order of Ecobridge district$\longrightarrow$Central park forest$\longrightarrow$Pulkoksan forest. Similarity index was calculated 20~23% between Ecobridge district$\longrightarrow$Central park, Pulkoksan forest. Therefore the highest species diversity and multistratum vegetation structure of Pulkoksan were the most suitable for the establishment to ecological space in the district.