• Journal of Biomedical Engineering Research
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• v.27 no.6
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• pp.418-426
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• 2006

In the artificial heart application, productivity and hemodynamic properties of artificial heart valves are crucial in successiful application to long term in vivo trials. This paper is about manufacture and assessment of trileaflet polymer heart valves using vacuum forming process(VFP). The VFP has many advantages such as reduced fabrication time, reproducibility due to relatively easy and simple process for manufacturing. Prior to VFP of trileaflet polymer heart valves, polyurethane(Pellethane 2363 80AE, Dow Chemical) sheet was prepared by extrusion. The sheets were heated and formed to mold shape by vacuum pressure. The vacuum formed trileaflet polymer heart valves fabrication is composed of two step method, first, leaflet forming and second, conduit forming. This two-step forming process made the leaflet-conduit bonding stable with any organic solvents. Hydrodynamic properties and hemocompatibility of the vacuum formed trileaflet polymer heart valves was compared with sorin bicarbon bileaflet heart valve. The percent effective orifice area of vacuum formed trileaflet polymer heart valves was inferior to bileaflet heart valve, but the increase of plasma free hemoglobin level which reflect blood damage was superior in vacuum formed trileaflet polymer heart valves Vacuum formed trileaflet polymer heart valves has high productivity, and superior hemodynamic property than bileaflet heart valves. Low manufacturing cost and blood compatible trileaflet polymer heart valves shows the advantages of vacuum forming process, and these results give feasibility in in vivo animal trials in near future, and the clinical artificial heart development program.

• Journal of Magnetics
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• v.11 no.1
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• pp.1-4
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• 2006

We report on the growth, structural and transport properties of zinc-blende CrAs/GaAs/MnAs/GaAs multilayers on GaAs(001) substrates. Structural analyses using in-situ reflection high-energy electron diffraction and exsitu cross-sectional transmission electron microscopy confirmed the realization of a zinc-blende crystal structure. Room temperature Hall measurements reveal that the as-grown multilayer exhibits p-type conductivity with a very low resistivity of $0.052\;\omega{cm}$, a high carrier concentration of $6.2X10^{19}\;cm^{-3}$ and a Hall mobility of $1.8\;cm^2/Vs$. We also observed a clear decrease of the resistivity in samples after low temperature annealing.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1662-1668
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• 2011

Steric and electronic parameters of 4'-substituents play significant roles in steering the conformation of nucleoside analogues. In order to investigate the relationship of 4'-substituent with antiviral enhancement, novel 4'-phenyl-5'-norcarbocyclic adenosine phosphonic acid analogues were racemically synthesized via de novo acyclic stereoselective route from propionaldehyde 5. The phenyl substituted cyclopentenols 15a and 15b as key intermediates were successfully constructed via reiterative carbonyl addition of Grignard reagents and ring-closing metathesis of corresponding divinyl 14. The synthesized nucleoside phosphonic acids analogues 19, 20, 21, and 23 were subjected to antiviral screening against HIV-1.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.75.2-75.2
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• 2019

This poster introduces the ongoing "Narrow-band Ca Photometry for Dwarf Spheroidal Galaxies" project and presents the latest results. The project aims to explain the formation and evolution of dwarf spheroidal galaxies by examining the structural properties of stellar populations as a function of metallicity. To overcome the lack of stars with known spectroscopic metallicities for dwarf spheroidal galaxies, we apply the hk index as a photometric metallicity indicator to three galaxies-Draco, Sextans, and Canes Venatici I. For all three galaxies, we found that metal-poor and metal-rich groups of red-giant-branch stars have distinct spatial distributions, in which metal-rich stars are centrally concentrated while metal-poor stars are relatively dispersed. In Sextans, we found an off-centered peak of metal-poor stars which is presumed to be a disrupting star cluster in this galaxy. We will discuss the implications of our results for the dwarf galaxy formation and possible directions on future work of this project.

• Journal of Construction Engineering and Project Management
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• v.4 no.1
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• pp.37-44
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• 2014

Comparatively, the construction industry has, on average, a higher rate of fatal and major injuries, work induced ill-health and damage to properties than other industrial sectors; and this is a source of concern to industry stakeholders. The study showed that although subcontracting could be contributory to an increase in workplace accidents in the construction industry, contractual aspects of subcontracting arrangements (such as the power imbalance that exist along the client-customer interface) also present opportunities for improvements in health and safety management (HSM) practices in organisations. This conclusion was reached after an analysis of a questionnaire survey (with a 27% response rate) that assessed the attitudes and perception to health and safety issues.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.194-195
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• 2015

When starting a new project, generally similar existing projet are searched. As Building Modeling Information(BIM) has short history and experience, the dependence on similar project is high. Small and medium sized design companies are depending on website search tool for information of BIM project besides companies maintaining the Database(DB) from lots of project experience. However, the information level and contents provided by websites differ drastically from each other which makes it difficult to utilize the information and apply cases. Furthermore, the different classification system of the sites makes the situation even worse. Therefore, we collected and analyzed over 100 BIM cases from 18 global websites, to develop a system for BIM case application. Result showed that over 90% of our subject pool provided basic information including the construction type, characteristics of the client (public/ private), location of the project, and detailed information such as primary usage. Moreover, the reasons for applying BIM where to solve problems of geometric design, building system like MEP and construction. Furthermore, there was a contrast between cases conducted only within Korea and cases conducted with other countries. While there was almost always helpful information regarding the administrative steps for Korean BIM cases, there was close to no information for projects carried out outside of Korea. These results could contribute to verifying the trend of information provision of the websites for BIM projects data, and this is believed to be helpful for developing an application system for BIM cases which have an organized information provision system and level as well as for bench marking.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.113-118
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• 2016

Project management is a tool for smooth operation during a full cycle from the design to normal operation including the schedule, document, and budget management, and document management is an important work for big projects such as the JRTR (Jordan Research and Training Reactor). To manage the various large documents for a research reactor, a project management system was resolved, a project procedure manual was prepared, and a document control system was established. The ANSIM (Advanced Nuclear Safety Information Management) system consists of a document management folder, document container folder, project management folder, organization management folder, and EPC (Engineering, Procurement and Construction) document folder. First, the system composition is a computerized version of the Inter-office Correspondence (IOC), the Document Distribution for Agreement (DDA), Design Documents, and Project Manager Memorandum (PM Memo) works prepared for the research reactor design. Second, it reviews, distributes, and approves design documents in the system and approves those documents to register and supply them to the research reactor user. Third, it integrates the information of the document system-using organization and its members, as well as users' rights regarding the ANSIM document system. Throughout these functions, the ANSIM system has been contributing to the vitalization of united research. Not only did the ANSIM system realize a design document input, data load, and search system and manage KAERI's long-period experience and knowledge information properties using a management strategy, but in doing so, it also contributed to research activation and will actively help in the construction of other nuclear facilities and exports abroad.

• Journal of Korean Society of Rural Planning
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• v.12 no.2 s.31
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• pp.65-73
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• 2006

This study attempts to develop an interim evaluation system for the Integrated Rural Village Cluster Development Project(IRVCDP) which can secure its identity and sustainability, and induce its early settlement, and to derive plans for its steady progress. The evaluation system consists of three levels. The highest-order level is evaluation purposes, which describe IRVCDP's goals. They are expansion of income bases(EIB), improvement of living environments(ILE), strengthening of regional capabilities(SRC) and constructing effective project operation system(CEPOS). The second level is evaluation items, which each characterize the relevant evaluation purposes. The last level is evaluation indices, which observe achievement f3r evaluation purposes. 22 evaluation indices are selected to satisfy the purposes of this study through a brainstorming process and a survey on opinions of experts for those evaluation purposes and evaluation items which are derived from analyzing the IRVCDP's properties. The relative importance of the evaluation indices selected are determined through the AHP analysis. The most intriguing result from the AHP analysis is that strengthening of regional capabilities is found to be the most important one among evaluation purposes. It can be said that this result is parallel to a ultimate goal of the IRVCDP.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.2
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• pp.101-113
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• 2011

As information and communication technology advances driving the rapid evolution of e-commerce and e-business becomes on effective marketing means for both business and institutions, the industry deals with these changes and has a profound, positive impact on production and operations management. But the construction industry falls behind compared with other industries in productivity, informationalization, automatization and globalization. Especially even though the informationalization is inevitable in any developing society, a number of construction industries can hardly cope with it properly. As the construction industry gets informationalized and advanced, the introduction of PMIS (Project Management Information System) is making progress actively for the effective construction project control and productivity improvement in construction. With the government officials' political promotion and the rising desire for construction informationalization of enterprises, many are attempting to develop integrated systems or to replace a previous system with a more advanced alternative. Construction Industry, however, has the peculiar properties that the period for the completion of construction is limited and on top of that, most of its data processing systems are seen as being an early stage in the design of management information systems. As a result, there are extremely few applications in the construction industry. In this paper, we propose the PMIS system based on new model 4CM that improves on previous models.

• The Journal of Advanced Prosthodontics
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• v.2 no.3
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• pp.81-87
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• 2010

PURPOSE. The purpose of this study was to compare the linear sintering behavior of presintered zirconia blocks of various densities. The mechanical properties of the resulting sintered zirconia blocks were then analyzed. MATERIALS AND METHODS. Three experimental groups of dental zirconia blocks, with a different presintering density each, were designed in the present study. Kavo $Everest^{(R)}$ ZS blanks (Kavo, Biberach, Germany) were used as a control group. The experimental group blocks were fabricated from commercial yttria-stabilized tetragonal zirconia powder (KZ-3YF (SD) Type A, KCM. Corporation, Nagoya, Japan). The biaxial flexural strengths, microhardnesses, and microstructures of the sintered blocks were then investigated. The linear sintering shrinkages of blocks were calculated and compared. RESULTS. Despite their different presintered densities, the sintered blocks of the control and experimental groups showed similar mechanical properties. However, the sintered block had different linear sintering shrinkage rate depending on the density of the presintered block. As the density of the presintered block increased, the linear sintering shrinkage decreased. In the experimental blocks, the three sectioned pieces of each block showed the different linear shrinkage depending on the area. The tops of the experimental blocks showed the lowest linear sintering shrinkage, whereas the bottoms of the experimental blocks showed the highest linear sintering shrinkage. CONCLUSION. Within the limitations of this study, the density difference of the presintered zirconia block did not affect the mechanical properties of the sintered zirconia block, but affected the linear sintering shrinkage of the zirconia block.