• Composites Research
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• v.34 no.6
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• pp.337-344
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• 2021

In this study, the progressive failure behavior of the composite fan blade dovetail element under tensile loading is numerically investigated through finite element(FE) simulation. The accuracy of prediction by FE simulation is verified through tensile testing. The dovetail element is one of the joints for coupling the fan blade with the disk in a turbofan engine. The dovetail element is usually made of a metal material such as titanium, but the application of composite material is being studied for weight reduction reasons. However, manufacturing defects such as drop-off ply and resin pocket inevitably occur in realizing complex shapes of the fan blade made by composite materials. To investigate the effect of these manufacturing defects on the composite fan blade dovetail element, we performed numerical simulation with FE model to compare the prediction of the FE model and the tensile test results. At this time, the cohesive zone model is used to simulate the delamination behavior. Finally, we found that FE simulation results agree with test results when considering thermal residual stress and through-thickness compression enhancement effect.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6D
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• pp.599-604
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• 2010

In this study, the value of travel time was estimated with reflecting the fuel cost according to travel distance. The main objective of this study is whether the addition of the fuel cost as a factor for route choice behavior is appropriate or not, through the stated preference survey. The route choice model was developed using SP survey technique with the consideration of level difference and the value of travel time, toll and fuel costs. Consequently, the fuel cost is identified as a main factor like travel time and toll cost in choosing routes from drivers' viewpoints. Nevertheless, since toll costs are recognized as out-of-pocket expenses whereas fuel costs as periodical expenses, it seems drivers are more sensitive to toll than fuel costs.

• Journal of Periodontal and Implant Science
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• v.54 no.2
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• pp.85-95
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• 2024

Purpose: Developmental endothelial locus-1 (DEL-1) plays a role in regulating neutrophil migration within the periodontium. The objective of this study was to evaluate the levels of DEL-1 in saliva and gingival crevicular fluid (GCF), as well as the number of neutrophils in patients with periodontitis. Methods: Forty systemically healthy, non-smoking periodontitis patients participated in this study. Clinical periodontal parameters, including the plaque index, probing pocket depth (PPD), clinical attachment level, bleeding on probing, modified sulcular bleeding index, and marginal bone level, were measured. Levels of DEL-1, interleukin (IL)-1β, IL-6, and IL-8 in unstimulated saliva samples, as well as DEL-1 in the GCF of 3 teeth from each participant, were assessed. Neutrophil counts in oral rinse and GCF samples were recorded. Spearman correlation coefficients were used to examine the correlation between protein levels, clinical parameters, and neutrophil quantities. Participants were divided into 2 age groups (those under 50 years and those 50 years or older) in order to investigate potential age-related differences. Results: DEL-1 levels in the GCF showed a negative relationship with PPD (sum). Neutrophils in oral rinse samples were positively correlated with PPD, IL-8, and IL-1β levels. Neutrophils in GCF exhibited a positive correlation with PPD (sum). Salivary DEL-1 levels showed correlations with IL-8 and IL-1β, but not with the clinical parameters of periodontitis. Conclusions: The negative relationship observed between PPD and GCF DEL-1 levels is consistent with the proposed protective role of DEL-1.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.6
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• pp.1-14
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• 2022

To alleviate the urban heat island phenomenon, this study aims to quantitatively analyze the effects of neighborhood green spaces on the improvement of the thermal environment based on detailed scenarios of five types of green spaces, including parks, pocket parks, parking lot greening, roadside planting, and rooftop-wall greening. The ENVI-met 4.4.6v model, a microclimate simulation program, was used to analyze the effects of green spaces. As a result, it was found that the air temperature decreased as the planting density of the park increased, but the thermal comfort index PET, which is the degree of heat sensation felt by humans, was not directly proportional to temperature. The establishment of a pocket park reduced air temperature up to a radius of 56m, while the range of temperature reduction increased by about 12.5% when three additional pocket parks were established at 250m intervals. Unlike the air temperature, PET was only affected in the vicinity of the planted area, so there was no significant difference in the thermal comfort of the surrounding environment due to the construction of pocket parks. Changing the surface pavement from asphalt to lawn blocks and implementing rooftop or wall greening did not directly act as solar shading but positively affected air temperature reduction; PET showed no significant difference. Roadside planting showed a higher air temperature reduction effect as the planting interval was narrower, but PET was not directly proportional to tree density. In the case of shrub planting under trees, it did not significantly affect the air temperature reduction but positively affected the improvement of thermal comfort. This study can outline strategies for constructing neighborhood green spaces to solve the urban heat island phenomena and establish detailed strategies for efficient thermal environment improvements.

• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.984-988
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• 2001

Since anti-angiogenesis could lead to the suppression of tumor growth, angiogenesis inhibitors have received particular attention for their therapeutic potential. In this study, two angiogenic inhibitors using the bioactive sequence from the kring le 5, AK1(KLYDY), AK2(KLWDF) were designed and synthesized. We have investigated their solution structures using NMR spectroscopy and their activities as angiogenesis inhibitors. AK2 has an intramolecular hydrogen bon d between the side chain amino proton of Lys1 and the carboxyl oxygen of Asp4 with a N ${\cdot}{\cdot}{\cdot}$O distance of $3.27\AA$, while AK1 shows more flexible structures than AK2. Indole ring in Trp is much bigger than the phenyl ring in Tyr and may have good face-to-edge interaction enforcing more rigid and constrained conformational features of AK2. Because of this relatively stable structure, Trp3 in AK2 may have better hydrophobic interaction with Phe5 than Tyr3 in AK1 if two adjacent aromatic groups are located in hydrophobic pocket of receptor. Since AK2 shows the similar anti-angiogenic activities to AK1, we are also able to confirm that the activity of AK1 is irrelevant to the Tyr phosphorylation. More rigid drug with higher activities can be provided by the mimetic approaches. For the further development of the angiogenesis inhibitors, these conformational studies on our lead peptides will be helpful in design of peptidomimetics.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1997.10a
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• pp.41-44
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• 1997

This paper is to provide an integration approach between design and process planning for mechanical parts, using feature recognition. We develop a method to extract each individual feature of an object from 3D modeling data using face-edge graph based algorithm and then propose an approach to recognize the volumic form features using heuristic rules. we demonstrate the proposed approaches are effective for such basic shapes as pocket, slot, through hole, etc.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.51-56
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• 2003

A custom application system, which was based on the finite element analysis, for stress on the head-skirt junction of a hot pressure vessel was developed. This is useful computer-based analysis system which designed to provide an analysis technique and knowledge conveniently available to other people. It was found the evaluation of thermal stress of several typed skirt joint of a pressure vessel could be performed early using this system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.691-700
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• 1994

Voronoi diagram of a set of geometric entities on a plane such as points, line segments, or arcs is a collection of Voronoi polygons associated with each entity, where Voronoi polygon of an entity is a locus of point which is closer to the associated entity than any other entity. Voronoi diagram is one of the most fundamental geometrical construct and well-known for its theoretical elegance and the wealth of applications. Various geometric problems can be solved with the aid of Voronoi diagram. For example, the maximum tool diameter of a milling cutter for rough cutting in a pocket can be easily found, and the pocketing tool path can be efficiently generated from Voronoi diagram. In PCB design, the design rule checking can be easily done via Voronoi diagram, too. This paper discusses an algorithm to construct Voronoi diagram of a simple polygon which consists of simple curves such as line segments as well as arcs in a plane with O(nlogn) time complexity by employing the divide and conquer scheme.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.826-829
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• 2002

This system is unionized form about CPS and a pocket game machine. This game machine of the use only for the game with an existing system but the function of various purposes which carries out service relevant to a user's position information. This system have the game function, the function to offer space guidance service by the theme interlocked with a user's position, and the traffic safety education function.

• Fashion & Textile Research Journal
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• v.8 no.5
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• pp.530-536
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• 2006

The purpose of this study was to classify the clusters based on two behavioral intentions toward purchasing originals and counterfeits of foreign fashion luxury brands and to examine the differences in personality characteristics and demographics. This study included attitude toward counterfeit, consumer ethnocentrism, materialism, and need for uniqueness as personality characteristics and gender, monthly household income, and pocket money as demographics. Data were gathered by surveying university students living in Seoul metropolitan area using convenient sampling, and 320questionnaires were used in the statistical analysis. In analyzing data, cluster analysis, x-test, and One-way ANOVA were conducted. As a result of the cluster analysis based on two behavioral intentions toward purchasing originals and counterfeits, four groups were identified. There were significant differences in attitude toward counterfeit and materialism according to the purchasing intention clusters. x-tests also showed there were significant differences between the number of male and female subjects in each of the four clusters. Females are significantly more represented than females in all four clusters.