• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.53-56
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• 2011

지난 7.7 DDoS(Distributed Denial of Service), 3.3 DDoS 대란을 통해서 보여주듯 DDoS 공격이 네트워크 주요 위협요소로 매우 부각되고 있으나, 공격에 대해서 실시간으로 감지하고 대응하기에 어렵다. 그리고 현재 여러 분야에서 매우 많은 용도로 사용되는 SMS(Short Message Service)도 DDoS 공격 수단으로 사용되어 이동전화 시스템에 큰 혼란을 야기할 수 있다. 기존의 Bloom Filter 탐지 기법은 구조가 간단하고 실시간 탐지가 가능한 장점을 갖지만 오탐지율에 대한 문제점을 가진다. 본 논문에서는 목적지 기반의 다중의 해시함수를 사용한 Counting Bloom Filter 기법을 이용하여 임계치 이상 카운트된 동일한 목적지로 발송되는 SMS에 대하여 공격으로 탐지하고 SMSC에 통보하여 차단시키는 시스템을 제안한다.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.134-134
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• 2010

Sea ices at the Tatarskiy Straitin the East/Japan Sea appear from November to April. Cold and fresh water, melted from the sea ices, may contain nutrients which are indispensable to spring bloom of phytoplankton and may provide a preferable condition to the spring bloom through changes in vertical structure of water column and stratification. Relation between the spring bloom along the Primorye coast and sea ices in the Tatarskiy Strait were investigated using multi-satellite multi-sensor data; ten-year SeaWiFS chlorophyll-a concentration data and PAR data, sea surface temperatures from NOAA/AVHRR, sea ice concentration and near-surface wind speed data from DMSP/SSMI, near-surface wind vectors from QuikSCAT, and others. We provided evidences of southwestward flowing cold water masses from sea ice and its relation of chlorophyll-a concentration. This study showed that year-to-year variations of chlorophyll-a concentration in spring were positively correlated with those of sea ice concentrations at the Tatarskiy Strait.

• ETRI Journal
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• v.33 no.5
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• pp.826-829
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• 2011

Distributed systems particularly suffer from Sybil attacks, where a malicious user creates numerous bogus nodes to influence the functions of the system. In this letter, we propose a Bloom filter-based scheme, SybilBF, to fight against Sybil attacks. A Bloom filter presents a set of Sybil nodes according to historical behavior, which can be disseminated to at least n (e-1)/e honest nodes. Our evaluation shows that SybilBF outperforms state of the art mechanisms improving SybilLimit by a factor of (1/e)${\gamma}$ at least.

• Journal of Korea Multimedia Society
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• v.19 no.8
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• pp.1597-1608
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• 2016

Recently, a number of solutions were proposed to address the challenges and issues of vehicular networks. Vehicular Cloud Computing (VCC) is one of the solutions. The vehicular cloud computing is a new hybrid technology that has a remarkable impact on traffic management and road safety by instantly using vehicular resources. In this paper, we study an important vehicular cloud service, content-based delivery, that allows future vehicular cloud applications to store, share and search data totally within the cloud. We design a VCC-based system architecture for efficient sharing of vehicular contents, and propose a Hierarchical Hybrid Content Delivery scheme using Bloom Filter (H2CDBF) for efficient vehicular content delivery in Vehicular Ad-hoc Networks (VANETs). The performance of the proposed H2CDBF is evaluated through an analytical model, and is compared to the proactive content discovery scheme, Bloom-Filter Routing (BFR).

• Proceedings of the KSRS Conference
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• v.2
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• pp.913-916
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• 2006

Spatial distribution, seasonal and interannual variability of chlorophyll a concentration in Okhotsk Sea from SeaWiFS data between 2001 and 2004 were describe. An Empirical Orthogonal Function method was applied for analysis data. The ten modes described about 85% of total variance. Two maxima were defined - more intensive in spring and weaker in autumn. The first mode showed zones with chlorophyll a concentration during maximum bloom. The second mode specified timing of spring bloom in various regions in Okhotsk Sea. Analysis of SeaWiFS data indicated connection between highest chlorophyll a concentration and sea surface temperature limits during spring bloom. Similar relation was not found during fall bloom.

• Journal of Environmental Impact Assessment
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• v.20 no.6
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• pp.915-925
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• 2011

Following the industrialization and urbanization in Korea, algal bloom causes aesthetic displeasure and many other problems such as taste and odor, coloration, scum, increase in pH, filter-bed blockage. There were some cases involving human death by microcystins during summertime in foreign countries. In Korea, Harmful cyanobacteria such as Microcystis and Anabaena develop in summer in the Daecheong reservoir, one of the main water resources, with the retention time of above 200 days. To better control algal bloom, the Ministry of Environment has been running algal bloom alert system from 1998 for the Daecheong reservoir, which needs to be improved to reflect the characteristics of river-type lakes. For this reason, we try to find new measures to improve an algal bloom alert system for each water zone considering the characteristics of harmful cyanobacteria in this study.

• Journal of The Korean Association of Information Education
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• v.22 no.2
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• pp.195-203
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• 2018

This thesis is to presented a theoretical fundamental of an assessment criteria available to a conventional curriculum because informatics subject matter education became it. We analyzed Bloom's Knowledge Dimension, Taxonomy that have suggested most general theoretical base in the educational assessment area. Also a programming area which can improve computational thinking can be the most important chapter of the informatics subject matter. Thus this thesis applied Bloom's theory to KAIE's informatics subject matter curriculum made by 2017. And the result of the qualitative research through the expert panel was 14 items, 87% of Conceptual, Procedural Knowledge and 12 items, 75% of Understand, Apply Taxonomy of Bloom's Theories in the 16 items of the curriculum outlines. Applying Bloom Criteria to like these can provide theoretical fundamental of assessment trend, development of assessment tool requested in the conventional education.

• Korean Journal of Environmental Biology
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• v.18 no.4
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• pp.447-456
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• 2000

Genus Prorocentrum of dinoflagellate has been known as representative causative algae of red tide in Masan-Jinhae Bay. Prorocentrum populations- P. dentatum Stein, p. micans Ehrenberg, P. minimum (Pavillard) Schiller and P. triestinum Schiller- were monitored from January 1990 to August 1997, Prorocentrum populations usually have bloomed during the water stratification periods from June to August. Water temperature ranged from 24$^{\circ}C$ to 28$^{\circ}C$ and salinity from 24$\textperthousand$ to 34$\textperthousand$ during the Prorocentrum blooms. Bloom magnitude of Prorooentrum populations gradually increased from offshore to inshore area of coastal embayment and this populations tended to concentrate from surface to 2.5m depth. Prorocentrum algal blooms have become more frequent and intense than those of 1980s and early 1990s. P. minimum was the most persistent species in terms of bloom frequency and cellular abundance.

• Journal of KIISE:Databases
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• v.36 no.2
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• pp.84-98
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• 2009

Various algorithms and architectures for IP address lookup have been studied to improve forwarding performance in the Internet routers. Previous IP address lookup architecture using Bloom filter requires a separate Bloom filter as well as a separate hash table in each prefix length, and hence it is not efficient in implementation complexity. To reduce the number of hash tables, it applies controlled prefix expansion, but prefix duplication is inevitable in the controlled prefix expansion. Previous parallel multiple-hashing architecture shows very good search performance since it performs parallel search on tables constructed in each prefix length. However, it also has high implementation complexity because of the parallel search structure. In this paper, we propose a new IP address lookup architecture using all-length Bloom filter and all-length multiple hash table, in which various length prefixes are accomodated in a single Bloom filter and a single multiple hash table. Hence the proposed architecture is very good in terms of implementation complexity as well as search performance. Simulation results using actual backbone routing tables which have $15000{\sim}220000$ prefixes show that the proposed architecture requires 1.04-1.17 memory accesses in average for an IP address lookup.

• Journal of Korea Foundry Society
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• v.39 no.1
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• pp.7-13
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• 2019

Few studies of large blooms over 700 mm thick among those used for the forging of raw materials have been reported. The cooling rate difference between the surface and the center of a large bloom is large, and the degradation of the mechanical properties is likely in cases involving excessively coarse precipitates resulted from the slow cooling rate of a large bloom after casting. Therefore, a schematic investigation of the growth behaviors of precipitates while varying their locations in blooms is necessary. The dissolution behaviors of precipitates were investigated by simulating a reheating process during which the bloom is heated to a high temperature. The segregation behavior of the as-cast large bloom was also investigated. Reheating specimens were obtained after an isothermal heat treatment at $1150^{\circ}C$ with various holding times to simulate the reheating process, with the samples undergoing a subsequent water quenching step. The precipitates were extracted using an electrolytic extractor and a particle size analysis was conducted with the aid of SEM, EDS, and TEM. In the present work, Al oxide, MnS and Nb carbide were mainly observed.