• Convergence Security Journal
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• v.9 no.2
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• pp.71-78
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• 2009

It is very difficult to apply previous security protocols to WSNs(Wireless Sensor Networks) directly because WNSs have resource constrained characteristics such as a low computing ability, power, and a low communication band width. In order to overcome the problem, we proposes a secure group communication scheme applicable to WSNs. The proposed scheme is a combined form of the TEEN(Threshold sensitive Energy Efficient sensor Network protocol) clustering based hierarchical routing protocol and security mechanism, and we assume that WSNs are composed of sensor nodes, cluster headers, and base stations. We use both private key and public key cryptographic algorithms to achieve an enhanced security and an efficient key management. In addition, communications among sensor nodes, cluster headers, and base stations are accomplished by a hierarchical tree architecture to reduce power consumption. Therefore, the proposed scheme in this paper is well suited for WSNs since our design can provide not only a more enhanced security but also a lower power consumption in communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2320-2334
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• 1999

In this paper, we propose multiple IS-MMBS service schemes for very low power and micro-size RMIMS (radio-interfaced micro information monitoring system) terminals. In MMBS service area, when new arrival RMIMS terminals have real-time traffic characteristic or large traffic bandwidth, only single IS-MMBS service scheme can not guarantee RMIMS terminal's QoS(quality of service) such as buffer overflow or packet loss. In this case, the proposed multiple IS-MMBS service schemes can be effectively used for QoS service of RMIMS terminal. According to clustering method of RMIMS terminals and MMBS segment method, the proposed schemes can be divided into terminal segment method, region segment method, application based segment method, traffic type based segment method, overlapping segment method and hybrid segment method

• Convergence Security Journal
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• v.12 no.6
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• pp.25-30
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• 2012

As the network composed of numerous sensor nodes, sensor network conducts the function of sensing the surrounding information by sensor and of the sensed information. Our military has also developed ICT(Information and Communication Technology) along with the methods for effective war by sharing smooth information of battlefield resources through network with each object. In this paper, a sensor network is clustered in advance and a cluster header (CH) is elected for clusters. Before deployment, a certificate is provided between the BS and the sensor nodes, and after clustering, authentication is done between the BS and the sensor nodes. Moreover, inter-CH authentication technique is used to allow active response to destruction or replacement of sensor nodes. Also, because authentication is done twice, higher level of security can be provided.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.3
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• pp.316-322
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• 2013

In order to evaluate the genetic diversity and discrimination among five Korean native chicken lines, a total of 86 individuals were genotyped using 150 microsatellite (MS) markers, and 15 highly polymorphic MS markers were selected. Based on the highest value of the number of alleles, the expected heterozygosity (He) and polymorphic information content (PIC) for the selected markers ranged from 6 to 12, 0.466 to 0.852, 0.709 to 0.882 and 0.648 to 0.865, respectively. Using these markers, the calculated genetic distance (Fst), the heterozygote deficit among chicken lines (Fit) and the heterozygote deficit within chicken line (Fis) values ranged from 0.0309 to 0.2473, 0.0013 to 0.4513 and -0.1002 to 0.271, respectively. The expected probability of identity values in random individuals (PI), random half-sib ($PI_{half-sibs}$) and random sibs ($PI_{sibs}$) were estimated at $7.98{\times}10^{-29}$, $2.88{\times}10^{-20}$ and $1.25{\times}10^{-08}$, respectively, indicating that these markers can be used for traceability systems in Korean native chickens. The unrooted phylogenetic neighbor-joining (NJ) tree was constructed using 15 MS markers that clearly differentiated among the five native chicken lines. Also, the structure was estimated by the individual clustering with the K value of 5. The selected 15 MS markers were found to be useful for the conservation, breeding plan, and traceability system in Korean native chickens.

• 한국해양학회지
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• v.17 no.2
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• pp.95-101
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• 1982

In order to the species composition and abundance distribution of zooplankton, quantitative samples collected in the Yellow Sea in April 1981 were analyzed. Ranges of temperatures and salinities of the study area were 4.55-9.80$^{\circ}C$ and 32.02-32.88 , respectively. Total 33 taxa were identified from all samples collected. Species composition along the stations showed no remarkable variations. Copepods were the most imporatnt components of zooplankton community in the study area. Dominant species of copepods were Oithona similis, Acartia clause and Centropages mcmurrichi. Appendicularia, Chaetognatha, Amphipod, and Euphausiid were distributed with minor abundance. Average biomass(wet weight) of zooplankton was 107mg/㎥, and the biomasses of zooplankton at offshore stations were greater than those of inshore stations in the study area. Average individual number of zooplankton was 1,915 indiv./㎥, and the variations along stations showed the same trend as in biomass. From the result of clustering with correlation coefficients calculated with the indivecual numbers per cubic meter for 20 zooplankton constituents at each station it was suggested that temperature had far reaching sffect on the distribution of zooplankton in the study area.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.1-15
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• 2017

Recently terrorism targets unspecified masses and causes massive destruction, which is so-called Super Terrorism. Many countries have tried hard to protect their citizens with various preparation and safety net. With inexpensive and advanced technologies of sensors, the surveillance systems have been paid attention, but few studies associated with the classification of the pedestrians' trajectories and the difference among themselves have attempted. Therefore, we collected individual trajectories at Samseoung Station using an analytical solution (system) of pedestrian trajectory by LiDAR sensor. Based on the collected trajectory data, a comprehensive framework of classifying the types of pedestrians' trajectories has been developed with data normalization and "trajectory association rule-based algorithm." As a result, trajectories with low similarity within the very same cluster is possibly detected.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.1-14
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• 2021

It is highly challenging to measure the efficiency of electric vehicle charging stations (EVCSs) because factors affecting operational characteristics of EVCSs are time-varying in practice. For the efficiency measurement, environmental factors around the EVCSs can be considered because such factors affect charging behaviors of electric vehicle drivers, resulting in variations of accessibility and attractiveness for the EVCSs. Considering dynamics of the factors, this paper examines the technical efficiency of 622 electric vehicle charging stations in Seoul using data envelopment analysis (DEA). The DEA is formulated as a multi-period output-oriented constant return to scale model. Five inputs including floating population, number of nearby EVCSs, average distance of nearby EVCSs, traffic volume and traffic congestion are considered and the charging frequency of EVCSs is used as the output. The result of efficiency measurement shows that not many EVCSs has most of charging demand at certain periods of time, while the others are facing with anemic charging demand. Tobit regression analyses show that the traffic congestion negatively affects the efficiency of EVCSs, while the traffic volume and the number of nearby EVCSs are positive factors improving the efficiency around EVCSs. We draw some notable characteristics of efficient EVCSs by comparing means of the inputs related to the groups classified by K-means clustering algorithm. This analysis presents that efficient EVCSs can be generally characterized with the high number of nearby EVCSs and low level of the traffic congestion.

• Atmosphere
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• v.31 no.5
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• pp.489-510
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• 2021

In this paper, we propose an algorithm for detecting convective initiation (CI) using GEO-KOMPSAT-2A/advanced meteorological imager data. The algorithm identifies clouds that are likely to grow into convective clouds with radar reflectivity greater than 35 dBZ within the next two hours. This algorithm is developed using statistical and qualitative analysis of cloud characteristics, such as atmospheric instability, cloud top height, and phase, for convective clouds that occurred on the Korean Peninsula from June to September 2019. The CI algorithm consists of four steps: 1) convective cloud mask, 2) cloud object clustering and tracking, 3) interest field tests, and 4) post-processing tests to remove non-convective objects. Validation, performed using 14 CI events that occurred in the summer of 2020 in Korean Peninsula, shows a total probability of detection of 0.89, false-alarm ratio of 0.46, and mean lead-time of 39 minutes. This algorithm can be useful warnings of rapidly developing convective clouds in future by providing information about CI that is otherwise difficult to predict from radar or a numerical prediction model. This CI information will be provided in short-term forecasts to help predict severe weather events such as localized torrential rainfall and hail.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.25-33
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• 2020

A drought event is characterized by duration, severity and affected area. In general, after calculating a drought index using hydro-meteorological time series at a station, a drought event is defined based on the run theory to identify the beginning and end time. However, this one-dimensional analysis has limitations for analyzing the spatio-temporal occurrence characteristics and movement paths of drought. Therefore, this study is to define a three-dimensional drought event using a simple clustering algorithm and to develop a drought map that can be used to understand the drought severity according to the spatio-temporal expansion of drought. As a result, compared with the two-dimensional monitoring information to show spatial distribution of drought index, a proposed drought map is able to show three-dimensional drought characteristics inclusing drought duration, spatial cumulative severity, and centroid of drought. The analysis of drought map indicated that there was a drought event which had the affected area less than 10 % while on occations while there were 11 drought events (44 %) which had the affected area more a than 90 % of the total area. This means that it is important to understand the relationship between spatial variation of drought affected area and severity corresponding to various drought durations. The development of drought map based on three-dimensional drought analysis is useful to analyze the spatio-temporal occurrence characteristics and propagation patterns of regional drought which can be utilized in developing mitigation measures for future extreme droughts.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.493-501
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• 2001

A study on the community structure of macrobenthos was accomplished around Kadugdo, a south coast of Korea. Sampling was performed bimonthly using a Smith-McIntyre grab ($0.05 m^2$) at ten stations from January to November, 1998. A total of 260 species was sampled with mean density of $1,729 ind./m^2$and biomass of $154.7 gwwt./m^2$during the study periods. Of these species, there were 96 species of arthropods ($37.0\%$), 89 species of annelids ($34.2\%$), 45 species of molluscs ($17.3\%$) and 30 species of others ($11.5\%$). Annelids were density-dominant faunal group with a mean density of $1,263 ind./m^2$which occupied $73.0\%$ of the total individual of benthic animals. Molluscs were represented as biomass-dominant faunal group with a mean biomass of $99.5 gwwt./m^2$ ($64.3\%$ of total biomass). The density-dominant species were a bivalvia Theora fragilis ($194 ind./m^2$) and five species of polychaetes, Lumbrineris longifolia ($177 ind./m^2$), Chaetozone setosa ($150 ind./m^2$), Sternaspis scutata ($116 ind./m^2$), Sigambra tentaculata ($106 ind./m^2$) and Hemipodus yenourensis ($94 ind./m^2$). And major biomass-dominant species was a bivalvia Ruditapes philippinarum ($45.6 gwwt./m^2$). Clustering analysis showed that the study area could be divided into two station groups and three stations: southwestern part of Kadugdo effected on Chinhae Bay, fisheries farming area and eastern part of Kadugdo effected on Nakdong River estuary.