• Composites Research
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• v.16 no.6
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• pp.16-22
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• 2003

This paper studied the AE(acoustic emission) characteristics of the laminated composite structures. The composite stiffened panels under the compressive loading emitted various AE signals when they buckled or changed the buckling modes. In addition, the failure initiated and propagation generated a lot of complex signals. From the continuous signal generation. we identified when the failures initiated and whether they propagated or not. The single lap joint of laminated plates under tensional load also generated AE signals when bonding region failed. The first failure occurrence and its propagation are monitored by generated AE signals. The characteristics of AE signals used in this analysis are cumulative hits, hit distribution, peak frequency of generated AE waveform and amplitude of signals. The analysis of AE signals shows that continuous increment of cumulative hits can be regarded as damage propagation and three dominant peak frequencies can correspond to typical failure modes in the laminated composites.

• The KIPS Transactions:PartC
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• v.10C no.7
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• pp.857-866
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• 2003

For detecting an intrusion based on the anomaly of a user's activities, previous works are concentrated on statistical techniques in order to analyze an audit data set. However. since they mainly analyze the average behavior of a user's activities, some anomalies can be detected inaccurately. In this paper, a new clustering algorithm for modeling the normal pattern of a user's activities is proposed. Since clustering can identify an arbitrary number of dense ranges in an analysis domain, it can eliminate the inaccuracy caused by statistical analysis. Also, clustering can be used to model common knowledge occurring frequently in a set of transactions. Consequently, the common activities of a user can be found more accurately. The common knowledge is represented by the occurrence frequency of similar data objects by the unit of a transaction as veil as the common repetitive ratio of similar data objects in each transaction. Furthermore, the proposed method also addresses how to maintain identified common knowledge as a concise profile. As a result, the profile can be used to detect any anomalous behavior In an online transaction.

• Journal of the Korean Institute of Gas
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• v.3 no.3 s.8
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• pp.45-50
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• 1999

The LPG refueling station's explosion at Bucheon city was a major accident which with rare frequency of occurrence and large damage effect. Therefore, to prevent similar accident in the future from LPG charging stations which located in urban area. It needs to identify the damage effects of such facilities by comparing theoretically quantities risk and actual damage. The BLEVE effects from the accident showed similar damage effect in case of heat flux, however, the overpressure level reflected at the reduced distance by $15\%$. The structure damage to the near by area showed comparatively large heat radiation damage to the concrete structure strength and shape changes through heat flux while the overpressure effect was small.

• Journal of Korean Society of Disaster and Security
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• v.15 no.4
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• pp.57-69
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• 2022

During the 10 years from 2011 to 2021, a whopping 2,800 people were killed or injured during port work. Among them, the frequency of occurrence at the port loading and unloading business is high. Container terminal operators must conduct risk assessments and establish reasonable safety measures in accordance with laws and regulations. As a research method, the contents of risk assessment presented in the Industrial Safety and Health Act, the Serious Accident Punishment Act, and the Special Act on Port Safety are presented through literature analysis. In this study, previous studies were analyzed to examine the risk assessment method and risk factors of container terminals. The purpose is to present 'industrial safety AI chatbot technology' that can improve the risk of safety accidents.

• Fire Science and Engineering
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• v.33 no.6
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• pp.53-62
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• 2019

A recent trend shows that more buildings are being constructed as mixed-use (residential and commercial) properties for efficient land use. This has led to an increased frequency in the occurrence of fires and the associated potential risks. In particular, in case of high-rise apartments, at least one of the elevators in each building is installed for evacuation purposes separately from the emergency elevator; therefore, for a combined ancillary room and emergency elevator platform situation, the structure is inevitably in series with the evacuation elevator platform. Thus, a proposal for a new type of ventilation zone based on existing national fire safety codes is required to achieve smoke control performance. To this end, the air egress velocity and differential pressure of each ventilation zone are checked using the "CONTAM" software; further, an alternative is proposed to secure smoke control performance for series structures.

• Journal of Advanced Navigation Technology
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• v.18 no.5
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• pp.483-489
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• 2014

Proposed electronic ballast circuit for harmonic reduction includes adding lossless snubber circuit to DC-DC converter. To get inverter for changing DC-AC, a lamp has been changed to equivalence resistance in the standard lamp voltage and current data, also inverter circuit has been interpreted by being changed to R, L, C equivalence circuit. Using converted equivalent circuit, the most suitable circuit constant which can satisfy the characteristics of fluorescent lamps has been decided on and finally designed. It could not only eliminate distortion waveform from pulsation frequency in inverter direct side current but also reduce considerably pulsation rate and switching loss by making input current of inverter discontinuous. The validity for the results of this study has been verified through the experiment to measure harmonic occurrence after applying a newly-manufactured product of electronic ballast to 40 W line tube style fluorescent lamps.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.508-515
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• 2020

This study examined the research trends of "Microplastic in food" with a scholar databaseusing the centrality analysis method. The data was based on research papers published from 2011 to 2020, sorted by "microplastic" and "food". The centrality analysis methodology(Degree centrality, Closeness centrality, Betweenness centrality) was applied, followed by a keyword-based frequency occurrence analysis. The results suggested that more than 30% of the total keywords were related to "marine" and "pollution". Therefore, research on the effects of microplastic pollution on the ecosystem had mainly been conducted. On the other hand, only 6% of the keywords were related to "toxicity" and "ingestion". Hence,the number of studies on microplastic exposure caused by bioaccumulation or food are still insufficient. These results can be used to provide directions for future research, as well as provide basic data for political decision-making on the environmental hazards of microplastic.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.5
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• pp.375-379
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• 2009

Protein domain is the conserved unit of compact tree-dimensional structure and evolution, which carries specific function. Domains may appear in patterns in proteins, since they have been conserved through the evolution for functional formation of proteins. In this paper, we propose a formulated method for conservation analysis of domain combination based on association rule. Proposed method measures mutual dependency of domains in a combination, as well as co-occurrence frequency of them, which is conventionally used. Based on the method, we extracted conserve domain combinations in S.cerevisiae proteins and analyzed their functions based on Gene Ontology. From the results, we drew conclusions that domains in S.cerevisiae proteins form patterns whose members are highly affiliated to one another, and that extracted patterns tend to be associated with molecular function. Moreover, the results testified to proposed method superior to conventional ones for identifying domain combinations conserved for functional cooperation.

• The Journal of the Korea Contents Association
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• v.10 no.2
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• pp.99-110
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• 2010

An event means a flow which has a time attribute such as a symptom of patient. Stream data collected by sensors can be summarized as an interval event which has a time interval between the start-time point and the end-time point in multiple stream data environment. Most of temporal mining techniques have considered only the frequent events. However, these approaches may ignore the infrequent event even if it is important. In this paper, we propose a new temporal data mining that can find association rules for the significant temporal relation based on interval events in multidimensional stream data environment. Our method considers the weight of events and stream data on the sensing time point of abnormal events. And we can discover association rules on the significant temporal relation regardless of the occurrence frequency of events. The experimental analysis has shown that our method provide more useful knowledge than other conventional methods.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.7
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• pp.76-81
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• 2011

A new via cutting structure in 2-layer DRAM package substrate has been fabricated to lower its power distribution network(PDN) impedance. In new structure, part of the via is cut off vertically and its remaining part is designed to connect directly with the bonding pad on the package substrate. These via structure and substrate design not only provide high routing density but also improve the PDN impedance by shortening effectively the path from bonding pad to VSSQ plane. An additional process is not necessary to fabricate the via cutting structure because its structure is completed at the same time during a process of window area formation. Also, burr occurrence is minimized by filling the via-hole inside with a solder resist. 3-dimensional electromagnetic field simulation and S-parameter measurement are carried out in order to validate the effects of via cutting structure and VDDQ/VSSQ placement on the PDN impedance. New DRAM package substrate has a superior PDN impedance with a wide frequency range. This result shows that via cutting structure and power/ground placement are effective in reducing the PDN impedance.