• Restorative Dentistry and Endodontics
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• v.43 no.3
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• pp.24.1-24.12
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• 2018

Objectives: The aim of this in vitro study was to evaluate the biocompatibility of newly proposed root-end filling materials, Biodentine, Micro-Mega mineral trioxide aggregate (MM-MTA), polymethylmethacrylate (PMMA) bone cement, and Smart Dentin Replacement (SDR), in comparison with contemporary root-end filling materials, intermediate restorative material (IRM), Dyract compomer, ProRoot MTA (PMTA), and Vitrebond, using human periodontal ligament (hPDL) fibroblasts. Materials and Methods: Ten discs from each material were fabricated in sterile Teflon molds and 24-hour eluates were obtained from each root-end filling material in cell culture media after 1- or 3-day setting. hPDL fibroblasts were plated at a density of $5{\times}10^3/well$, and were incubated for 24 hours with 1:1, 1:2, 1:4, and 1:8 dilutions of eluates. Cell viability was evaluated by XTT assay. Data was statistically analysed. Apoptotic/necrotic activity of PDL cells exposed to material eluates was established by flow cytometry. Results: The Vitrebond and IRM were significantly more cytotoxic than the other root-end filling materials (p < 0.05). Those cells exposed to the Biodentine and Dyract compomer eluates showed the highest survival rates (p < 0.05), while the PMTA, MM-MTA, SDR, and PMMA groups exhibited similar cell viabilities. Three-day samples were more cytotoxic than 1-day samples (p < 0.05). Eluates from the cements at 1:1 dilution were significantly more cytotoxic (p < 0.05). Vitrebond induced cell necrosis as indicated by flow cytometry. Conclusions: This in vitro study demonstrated that Biodentine and Compomer were more biocompatible than the other root-end filling materials. Vitrebond eluate caused necrotic cell death.

• Journal of the Korean Geographical Society
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• v.46 no.2
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• pp.181-196
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• 2011

The purpose of this study is to explore the network city in detail as a new model for explaining urban growth in the changing economic environment in recent years. For this purpose, starting from Batten's (1995) pioneering work on network city in the mid 1990s to the most recent ones, literature is reviewed and various aspects of network city model are examined including formation process, spatial structure, application to management and urban planning, and growth potential. With this, the study aims at providing comprehensive knowledge necessary for evaluating if the network city model is appropriate in explaining the urban phenomena in the 21st century. The result of the review shows that network city model is the one appropriately explaining the changing urban system associated with the economic globalization and the development of transport and information technology. In addition, more and more European city governments tend to adopt this as the urban planning principle.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.1
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• pp.114-128
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• 2014

This study is the analysis on the labor migration between 16 provinces in experienced employees' sector by using the employment insurance statistics of 2008 to 2011. In wage workers of Korea, all of regular and some of temporary employees subscribe to the employment insurance and among these, about 40-50% career workers have moved their jobs every year. Targeting these, first I perform cluster analysis to explore the spatial boundaries of intra and inter-regional labor migration, and second measure the regional linkages extracting the inter-regional migrants. As results, the clusters of labor migration are similar to 5+2 Mega-regional Economic Zones. However, in the regional linkages between clusters, Seoul-metropolitan area has a great influence to other regions in inflow and outflow.

• Journal of Electrical Engineering and Technology
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• v.13 no.3
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• pp.1317-1325
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• 2018

A generator-grid coupling calculation model is established to study the leading-phase operational capability of a 770 MW jumbo hydro-generator in a Chinese ultra-mega hydropower station. The static and dynamic stability of the generator are analyzed and calculated to obtain stability limits under leading-phase operating conditions. Three-dimensional (3D) time-varying nonlinear moving electromagnetic and temperature field models of the generator end-region are also established and used to determine the magnetic field, loss, and temperature of the end-region under the leading-phase operating condition. The simulation results agree with data measured from the actual 770 MW hydro-generator. This paper provides reliable reference data for the leading-phase operation of a jumbo hydro-generator, which will help to improve in the design and manufacture of future hydro-generators.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.123-127
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• 2015

Objectives: Glide path preparation is recommended to reduce torsional failure of nickel-titanium (NiTi) rotary instruments and to prevent root canal transportation. This study evaluated whether the repetitive insertions of G-files to the working length maintain the apical size as well as provide sufficient lumen as a glide path for subsequent instrumentation. Materials and Methods: The G-file system (Micro-Mega) composed of G1 and G2 files for glide path preparation was used with the J-shaped, simulated resin canals. After inserting a G1 file twice, a G2 file was inserted to the working length 1, 4, 7, or 10 times for four each experimental group, respectively (n = 10). Then the canals were cleaned by copious irrigation, and lubricated with a separating gel medium. Canal replicas were made using silicone impression material, and the diameter of the replicas was measured at working length (D0) and 1 mm level (D1) under a scanning electron microscope. Data was analysed by one-way ANOVA and post-hoc tests (p = 0.05). Results: The diameter at D0 level did not show any significant difference between the 1, 2, 4, and 10 times of repetitive pecking insertions of G2 files at working length. However, 10 times of pecking motion with G2 file resulted in significantly larger canal diameter at D1 (p < 0.05). Conclusions: Under the limitations of this study, the repetitive insertion of a G2 file up to 10 times at working length created an adequate lumen for subsequent apical shaping with other rotary files bigger than International Organization for Standardization (ISO) size 20, without apical transportation at D0 level.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.57-57
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• 2007

Aspheric glass lenses have many optical advantages, for glass have superior optical performance and an aspheric form can reduce optical aberrations. Recently, the use of it is rapidly expanding as the mass production becomes possible by glass molding press and so this method is considered as the best method for fabricating an aspheric glass lens, but it is difficult to control many parameters for pressing and cooling process. Design of experiments (DOE) is a very useful tool to design and analyze complicated industrial design problems. This study investigated the pressing conditions to mold aspheric glass lenses for mega pixel phone camera module using DOE method. We have applied fractional factorial design and the response variable was set form accuracy (PV) of aspheric surface of molded lens. The results of analysis indicates that all factors expect for pressing force of each step are available for the form accuracy (PV). It was the optimum condition of the designed pressing conditions for lowering the form accuracy(PV) value of molded lens that all factors were at the low level. The form accuracy (PV) of mold and molded lens under the optimum condition are $0.85\;{\mu}m$ and $0.922\;{\mu}m$ respectively.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.275-285
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• 2008

The "logistics industry" is recommended as an economic growth power in the future in Korea. In the past, Korea has handled China's freight volume overflow as a transfer hub. However, recently China has been constructing its own port facilities and many mega fleets have been moving to China's ports. As a result, the position of Korea's hub-ports facing a crisis. Now, new strategies are necessary for renovating Korea's logistics industry and international competitiveness. This study proposes a "value-added logistics cluster" as a new strategy. In particular, this study proposes a Korean value-added logistics cluster that maximizes Korea's locational and industrial advantages. Additionally, a model for a value-added logistics cluster is proposed for the rehabilitation of Korea's ports as logistics hubs in Northeast Asia. Many analyses are executed step-by-step to develop a Korean value-added logistics cluster model, such as an analysis of the relationship between the logistics industry and other industries for the definition of cluster components. Lastly, the Korean value-added logistics cluster model is applied to Kwangyang port, which is currently confronted with a crisis because of the decrease of freight volume.

• Journal of the Korean Society of Radiology
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• v.4 no.2
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• pp.31-35
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• 2010

In this study, we surveyed students recognition of the base units and radiation related units among international standard units, and determined the necessity of unit education. The survey was conducted using a questionnaire composed of 18 questions, and in the survey, students at the Radiology Department were asked about recognition and education. According to the results of the survey, around 44% of the students answered wrongly on base unit kV, and around 28% answered wrongly on km. Particularly with regard to the relation between units and numbers, around 57% of the students chose wrong answers. As to prefix mega and giga, respectively, 22% and 20% of the students chose wrong answers. To the question on radiation related unit Sv, around 30% gave wrong answers. Recognition of radiation related units was higher in senior students. To the question of whether to have received special education on units, over 50% of the students replied negatively. These results suggest the necessity of education on international standard units.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.236-236
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• 2015

Flood is one of the major natural disasters affecting millions of people. Thailand also, frequently faces with this type of disaster. Especially, 2011 mega flood in Central Thailand, inundated highway severely attributed to the failure of national economic and risk to life. Lesson learned from such an extreme event caused flood monitoring and warning becomes one of the sound mitigations. The highway flood hazard mapping accomplished in this research is one of the strategies. This is due to highway flood is the potential risk to life and limb, and potential damage to property. Monitoring and warning therefore help reducing live and property losses. In this study, degree of highway flood hazard was assessed by weighting factors for each cause of the highway flood using Multi Criteria Analysis (MCA) based Analytic Hierarchy Process (AHP). These weighting factors are the essential information to classify the degree of highway flood hazard to enable pinpoint on flood monitoring and flood warning in hazard areas. The highway flood causes were then investigated. It was found that three major factors influence to the highway flood are namely the highway characteristics, the hydrological characteristics and the land topography characteristics. The weight of importance for each cause of the highway flood in the whole country was assessed by weighting 3 major factors influence to the highway flood. According to the result of MCA analysis, the highway, the hydrological and the land topography characteristics were respectively weighted as 35, 35 and 30 percent influence to the cause of highway flood. These weighting factors were further utilized to classify the degree of highway flood hazard. The Weight Linear Combination (WLC) method was used to compute the total score of all highways according to each factor. This score was later used to categorize highway flood as high, moderate and low degree of hazard levels. Highway flood hazard map accomplished in this research study is applicable to serve as the handy tool for highway flood warning. However, to complete the whole warning process, flood water level monitoring system for example the camera gauge should be installed in the hazard highway. This is expected to serve as a simple flood monitor as part of the warning system during such extreme or critical event.

• Journal of Veterinary Science
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• v.22 no.6
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• pp.67.1-67.7
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• 2021

Background: Chlamydophila felis, formerly known as Chlamydia psittaci var. felis, is frequently associated with ocular, respiratory, and occasionally reproduction tract infections. Even though the infection is sometimes asymptomatic, it potentially results in a latent immunosuppressive infection. Objective: This study aimed to identify occurrences of feline chlamydophilosis, rarely reported in cats in Indonesia. Methods: The observation was conducted in three cats with clinical signs of Cp. felis infection, particularly relapsing conjunctivitis. The cats' histories were recorded based on owners' information. Conjunctival swabs were sampled for cytology examination and molecular assay detection. A phylogenetic tree was generated using MEGA-X software to reveal group clustering. A post-mortem examination was performed on the cat that died during an examination. Results: Cp. felis was detected in both cytological examination and polymerase chain reaction assay. The phylogenetic tree demonstrated that the Cp. felis isolated in this study clustered with several other isolates from the other countries. Cp. felis can be isolated from cats with different clinical manifestations and levels of severity. The chronic fatal infection demonstrated interstitial broncho-pneumonia under histopathological examination. Conclusions: Molecular assay of Cp. felis is always recommended to obtain a definitive diagnosis of feline chlamydophilosis since the disease can have various clinical manifestations. Even though it may be subclinical and is often not fatal, an infected cat may be a carrier that could spread the pathogen in the surrounding environment. Serious disease management is suggested to avoid high costs associated with regularly relapsing disease.