• Korea-Australia Rheology Journal
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• v.14 no.4
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• pp.189-201
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• 2002

The interaction between hydrophobically modified hydroxyethyl cellulose (hmHEC), containing approximately 1 wt% side-alkyl chains of $C_{16}$, and an anionic sodium dodecyl sulphate (SDS) surfactant was investigated. For a semi-dilute solution of 0.5 wt% hmHEC, the previously observed behaviour of a maximum in solution viscosity at intermediate SDS concentrations, followed by a drop at higher SDS concentrations, until above the cmc of surfactant when the solution resembles that of the unsubstituted polymer, was confirmed. Additionally, a two-phase region containing a hydrogel phase and a water-like supernatant was found at low SDS concentrations up to 0.2 wt%, a concentration which is akin to the critical association concentration, cac, of SDS in the presence of hmHEC. Above this concentration, SDS molecules bind strongly to form mixed micellar aggregates with the polymer alkyl side-chains, thus strengthening the network junctions, resulting in the observed increase in viscosity and elastic modulus of the solution. The shear behaviour of this polymer-surfactant complex during steady and step stress experiments was examined In great detail. Between SDS concentrations of 0.2 and 0.25 wt%, the shear viscosity of the hmHEC-polymer complex network undergoes shear-induced thickening, followed by a two-stage shear-induced fracture or break-up of the network. The thickening is thought to be due to structural rearrangement, causing the network of flexible polymers to expand, enabling some polymer hydrophobic groups to be converted from intra- to inter-chain associations. At higher applied stress, a partial local break-up of the network occurs, while at even higher stress, above the critical or network yield stress, a complete fracture of the network into small microgel-like units, Is believed to occur. This second network rupture is progressive with time of shear and no steady state in viscosity was observed even after 300 s. The structure which was reformed after the cessation of shear is found to be significantly different from the original state.

• Journal of the Korean Regional Science Association
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• v.31 no.2
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• pp.3-28
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• 2015

While industrial ecology theories and policy approaches have been considerably influential in regional economy, the dynamism and limitations of regional venture ecosystem are less clearly examined. In particular, the activities of strategic network brokerage require further research in relation to its internal and external interactions and collaborative mechanisms. Based on the analysis results of conditions of Daegu Gyeongbuk regional venture firms, this article examines the necessities of strategic network brokerage in regional venture ecosystem in the dimensions of network conditions as the intrinsic limitations, of innovation direction method outcome as the extrinsic trends, and of the related regional demands. In particular, this article tries to explore the roles and activity scopes of strategic network brokerage to contribute for making up for the weakness of diverse network infrastructures of regional venture ecosystem, for dealing with the mismatch for the extrinsic change trends of industrial technologies, and for fulfilling the strengthening trends of intrinsic capacities.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.97-101
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• 2005

High strength concretes utilizing EVA with micro particles were prepared by varying polymer/binder mass ratio and curing conditions with a constant water/binder mass ratio of 0.3. The EVA modified concretes on the compressive and flexural strength, microstructure, ultrapulse modulus in curing condition(dry and water curing) were studied. Also, scanning electron microscope analysis(SEM) was performed to reveal the presence of polymer film and cement hydrates in the concrete. The compressive strength of the EVA modified concretes cured at water conditions ere higher than that of the EVA modified concretes cured at dry conditions. But, the flexural strength of the specimens cured at dry conditions were higher than that of the specimens cured at water conditions. Due to the interaction of the cement hydrates and polymer film, an interpenetrating network originated in which the aggregates were embedded. The curing of the polymer modified concrete involves two step of cement hydrates and polymer modification, and cement hydrates was promoted in water conditions and polymer film formation take place when water evaporates and was thereby was favored in dry conditions. By SEM analysis, influences of polymer modification was strengthening of the transition zone between the aggregate and the paste, and the porosity of transition zone decreases. By spring analysis, it could known that polymer film affects in porosity decrease and strengthening of transition zone.

• Korean System Dynamics Review
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• v.12 no.2
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• pp.69-94
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• 2011

Daejeon, encompassing Daedeok Science Town and Daedeok Innopolis, possesses the advantage of portraying relatively higher regional innovation capacity and facilitating network formation among regional professional research organizations. Applying the Social Network Analysis(SNA) techniques, this paper focuses on divulging structural and spatial characteristics of the Daejeon Information and Communication(ICT) industry network, analyzing co-research projects implemented by the Daejeon-based universities. For the analytical tool, it depends on NETMINER 3.0. Furthermore, based on the Systems Thinking approaches, this study suggests a couple of policy implications. Judging from the Korea Standard Industrial Classification principles, the existing ICT industry is subdivided into 11 sub-industries. The highest degree centralization value comes from the Mobile Communication sub-industry(188.668%), indicating that Mobile Communication sub-industry exerts the most significant impact on the regional innovation networking in Daejeon. Among various stakeholders, Korea Advanced Institute of Science and Technology(KAIST) records the top ranking in most categories, conspicuously leading the institute-industry linkage. In terms of the ICT spatial distribution, the intra-regional cooperation examples present the strongest linkage values, followed by Daejeon-the Capital Region ones. Finally, as well shown in a series of causal loop analyses, this study recommends that Daejeon should put top policy priority in strengthening the internal ICT network within Daejeon proper. Here, Daejeon should keep in mind the fact that there exist reinforcing loops between Daejeon's attractiveness and the entering of new ICT firms.

• Proceedings of the KSR Conference
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• 2008.06b
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• pp.27-41
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• 2008

Construction of metro transportation infra is a large-scale project requiring tremendous financial resources. This study suggests operation method to use for rapid transit line existing infra such as Gyeongbu line and spare line capacity following second phase KTX construction. Reviewing various constraints of metro rapid transit operation, we found that the conditions for metro rapid transit operation are already satisfied in Daegu area, just like the case of Gyeongbu line in Seoul Metro area. Also, the evaluation of the economic feasibility of metro rapid transit operation in Daegu area shows that B/C is about 2.4, which implies that there is sufficient economic feasibility. According to the result of sensitivity analysis, the project is economically feasible unless the passenger demand decreases 15% and construction costs increases more than 70%. B/C is evaluated large because the utilization of already exiting infra lowers the initial cost. As one of mass transportation system of large capacity, metro rapid transit can generate significant spillover effect: It will strengthen competitiveness of metro area by connecting cities within the area and by extending one-day life zone of the area, to say nothing of the benefit of improving traffic condition. The construction of metro rapid transit network is necessary for the mass transportation system of Yeongnam area as well as Daegu area, and it may work as a starting point for uniting Daegu and Gyeongbuk and strengthening regional competitiveness.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.8
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• pp.4021-4037
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• 2018

In network intrusion detection research, two characteristics are generally considered vital to building efficient intrusion detection systems (IDSs): an optimal feature selection technique and robust classification schemes. However, the emergence of sophisticated network attacks and the advent of big data concepts in intrusion detection domains require two more significant aspects to be addressed: employing an appropriate big data computing framework and utilizing a contemporary dataset to deal with ongoing advancements. As such, we present a comprehensive approach to building an efficient IDS with the aim of strengthening academic anomaly detection research in real-world operational environments. The proposed system has the following four characteristics: (i) it performs optimal feature selection using information gain and branch-and-bound algorithms; (ii) it employs machine learning techniques for classification, namely, Logistic Regression, Naïve Bayes, and Random Forest; (iii) it introduces bulk synchronous parallel processing to handle the computational requirements of large-scale networks; and (iv) it utilizes a real-time contemporary dataset generated by the Information Security Centre of Excellence at the University of Brunswick (ISCX-UNB) to validate its efficacy. Experimental analysis shows the effectiveness of the proposed framework, which is able to achieve high accuracy, low computational cost, and reduced false alarms.

• Journal of Information Technology Applications and Management
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• v.19 no.4
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• pp.1-18
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• 2012

This paper identifies technology trends of national research and development (national R&D) by exploiting Korean national R&D patents, ranging from 2007 to 2010. In this paper, co-word analysis (CWA), which is a method to identify the relationship among technology terms by using their co-occurrences, is incorporated into network analysis to visualize the relationships among technology keywords of national R&D patents and calculate network indexes concerning inter-relationship diversity and strength of technology keywords. As a result, this research found that inter-relationship among technology keywords in national R&D are getting increasingly strengthening in an overall sense. In addition, the keyword inter-relationship diversity-strength map proposed in this paper revealed some significant technological keywords of national R&D : core technology keywords including "sensor", "film" and "fuel" and emerging keywords including "biosensor" and "thermoelectric". Because the proposed approach helps identify interdisciplinary trends of technology keywords from a massive volume of national R&D patents in a visual and quantitative way, we expect that the approach can be incorporated as a preliminary into the R&D planning process to assist R&D policy makers to understand technology convergence of national R&D and develop relevant R&D policies.

• Structural Engineering and Mechanics
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• v.87 no.6
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• pp.517-527
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• 2023

The severe deterioration of structures has led to extensive research on the development of structural repair techniques using composite materials. Consequently, previous researchers have devised various analytical methods to predict the interface performance of bonded repairs. However, these analytical solutions are highly complex mathematically and necessitate numerous calculations with a large number of iterations to obtain the output parameters. In this paper, an artificial neural network prediction models is used to calculate the interfacial stress distribution in RC beams strengthened with FRP sheet. The R2value for the training data is evaluated as 0.99, and for the testing data, it is 0.92. Closed-form solutions are derived for RC beams strengthened with composite sheets simply supported at both ends and verified through direct comparisons with existing results. A comparative study of peak interfacial shear and normal stresses with the literature gives the usefulness and effectiveness of ANN proposed. A parametrical study is carried out to show the effects of some design variables, e.g., thickness of adhesive layer and FRP sheet.

• Journal of Information Technology Applications and Management
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• v.29 no.6
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• pp.1-12
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• 2022

In recent years, technological competition in the automobile sector is accelerating. This study analyzes the status of patents from a global perspective of three promising future items that Korea has selected as core technologies in the field of autonomous driving,. And the technological cooperation ecosystem was identified through network analysis centered on scientific metrology. As a result of the analysis, it was confirmed that the growth of individual technologies has been strengthened in recent years, and although key source technologies have been largely preempted in major global countries, a close cooperative ecosystem between institutions, companies, and universities in major countries has not yet been formed. Specifically, the US and Japan have the technological leadership, while China is rapidly rising, and Korea is chasing after it as a latecomer. Therefore, it is necessary to continuously strengthen technological cooperation such as R&D of core technology to overcome technological limitations and strengthening of infrastructure construction, attracting excellent foreign talents and international exchanges. This analysis is meaningful in that it explores the global status of Korea's technology and the possibility of technological cooperation from various perspectives in the future from the viewpoint of preoccupation of future technology, rather than grasping the trend of a specific technology.

• Korean Security Journal
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• no.38
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• pp.83-107
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• 2014

As a part of school safety network construction project, a system of school marshal in Seoul-si and a project of academy safety guard in other regions are on the way of improvement. But, the crimes in and around the school, occurring frequently, are not solved easily, as this study points out. The effective improvement way of school safety network construction project is as followings. First, to enforce assistant-class school safety teacher system in order to nurture and educate experts in school safety, as a systematic support for strengthening occupational professionalism. Second, to enforce school safety network construction projects for construct circumstances through legal fix of school safety CPTED to make students free from crimes. This study looks into the real status and problem of school safety networks, and suggests system of school safety teacher and a legal enactment of CPTED, as systematic and a planed school safety countermeasure, not temporary.