• Advances in nano research
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• v.13 no.3
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• pp.247-257
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• 2022

Extraordinary properties of nanocomposites make them a primary replacement for many conventional materials. Anterior cruciate ligament (ACL) reconstruction, which is a frequent surgery in sport activities, is one of the fields in which nanocomposites could be utilized. In the present study, the mechanical properties of different porous scaffolds made from graphene nano-composites are presented ad load bearing capacity of these materials is calculated using finite element method. The numerical results are further compared with experimental published data. In addition, several geometrical and material parameters are analyzed to find the best configuration of nanocomposite scaffolds in reconstruction of ACL. Moreover, coating of detoxification chemicals are extremely easier on the nano-structured materials than conventional one. Detoxification potential of nano-composites in the injured body are also discussed in detail. The results indicated that nano-composite could be successfully used in place of auto- and allografts and also instead of conventional metallic screws in reconstruction of ACL.

• Journal of the Korean Society for Library and Information Science
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• v.23
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• pp.207-261
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• 1992

The purpose of this study is (1) to design and test a database which can be automatically classified, and (2) to generate automatic classification number by processing the keywords in titles using the code combination method of Colon Classification(CC) as well as an automatic recognition of subjects in order to develop an automatic classification system (Auto BC System) based on CC which can be applied to any research library. To conduct this study, 1,510 words in the fields of agricultrue and medicine were selected, analized in terms of [P], [M], [E], [S], [T] employed in CC, and included in a database for classification. For the above-mentioned subject fields, the principle of an automatic classification was specified in order to generate automatic classification codes as well as to perform an automatic subject recognition of the titles included. Whenever necessary, editing, deleting, appending and reindexing of a database can be made in this automatic classification system. Appendix 1 shows the result of the automatic classification of books in the fields of agriculture and medicine. The results of the study are summarized below. 1. The classification number for the title of a book can be automatically generated by using the facet principles of Colon Classification. 2. The automatic subject recognition of a book is achieved by designing a database making use of a globe-principle, and by specifying the subject field for each word. 3. The automatic subject-recognition of input data is achieved by measuring the number of searched words by each subject field. 4. The combination of classification numbers is achieved by flowcharting of classification formular of each subject field. 5. The efficient control of classification numbers is achieved by designing control codes on the database for classification. 6. The automatic classification by means of Auto BC has been proved to be successful in the research library concentrating on a Single field. The general library may have some problem in employing this system. The automatic classification through Auto BC has the following advantages: 1. Speed of the classification process can be improve. 2. The revision or updating of classification schemes can be facilitated. 3. Multiple concepts can be expressed in a single classification code. 4. The consistency of classification can be achieved with the classification formular rather than the classifier's subjective judgement. 5. A user's retrieving process can be made after combining the classification numbers through keywords relating to the material to be searched. 6. The materials can be classified by a librarian without subject backgrounds. 7. The large body of materials can be quickly classified by means of a machine processing. 8. This automatic classification is expected to make a good contribution to design of the total system for library operations. 9. The information flow among libraries can be promoted owing to the use of the same program for the automatic classification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.656-660
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• 2002

The fiber reinforced composite material is widely used in the multi-industrial field where the weight reduction of the infrastructure is demanded because of their high specific modulus and specific strength. Pressure vessels using this composite material in comparison with conventional metal vessels can be applied in the field where lightweight and the high pressure is demanded from the defense and aerospace industry to rocket motor case due to the merits which are energy curtailment by the weight reduction and decrease of explosive damage precede to the sudden explosion which is generated by the pressure leakage condition. In this paper, for nonlinear finite element analysis of E-glass/epoxy filament winding composite pressure vessel receiving an internal pressure, the standard interpretation model is developed by using the ANSYS 5.7.1, the general commercial program, which is verified as the accuracy and useful characteristic of the solution based on Auto LISP and ANSYS APDL. Both the preprocessor for doing exclusive analysis of filament winding composite pressure vessel and postprocessor that simplifies result of analysis have been developed to help the design engineers.

• Journal of The Korean Association of Information Education
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• v.8 no.4
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• pp.489-500
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• 2004

In this paper, an investigation on internet safety of 244 national or public elementary schools' web sites was performed with two points of view : inappropriate material posting and personal information exposure. The investigation results showed that obscene materials and commercial advertisements were uploaded into the bulletin board(67.2%) and students' personal information such as photograph, address, telephone number were exposed(87.3%). Most of the inappropriate materials were posted by auto-register programs. This problem was occurred due to reckless bulletin board opening and inappropriate management. On the contrary, personal information was exposed by teachers and students. They didn't not care about their personal information. It shows the fact that they have not recognized the danger of personal information exposure. Therefore managing real-name membership and enforcing permission to bulletin board were required to construct and use a safe school web site. Teachers have to understand not only negative effects appeared in a school web site but also latent dangerous factors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.933-937
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• 2002

The fiber reinforced composite material is widely used in the multi-industrial field where the weight reduction of the infrastructure is demanded because of their high specific modulus and specific strength. Pressure vessels using this composite material in comparison with conventional metal vessels can be applied in the field where lightweight and the high pressure are demanded from the defense and aerospace industry to rocket motor case due to the merits which are energy cutdown the weight reduction and decrease of explosive damage preceding to the sudden explosion which is generated by the pressure leakage condition). In this paper, for nonlinear finite element analysis of E-glass/epoxy filament winding composite pressure vessel receiving an internal pressure, the standard interpretation model is developed by using the ANSYS, general commercial software, which is verified as the accuracy and useful characteristic of the solution based on Auto LISP and ANSYS APDL. Both the preprocessor for doing exclusive analysis of filament winding composite pressure vessel and postprocessor that simplifies result of analysis have been developed to help the design engineers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.453-459
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• 2004

An axially staged combustor equipped with an LPP combustion system and CMC liner walls has been investigated for stable combustion and low NOx emissions for the ESPR project. Several fuel injectors were designed and manufactured for the LPP burner, and single sector combustor tests were conducted to evaluate fundamental combustion characteristics such as emissions, instabilities, auto-ignition, and flash back at typical operating conditions from idle to Mn 2.2 cruise. The latest test results showed that the LPP burner had a good potential for the low NOx target. It was also found that the NOx emission level was greatly affected by a distortion in the air flow velocity field upstream of the LPP burner due to the diffuser and fuel feed arm. The CMC material was investigated to apply for the high temperature and low NOx combustor. Annular combustor liner walls were manufactured with the CMC material, and they have been tested at low pressure conditions to evaluate the soundness of the material and the mounting and seal system. This paper reports the latest research activities on the LPP combustion system and CMC liner walls for the ESPR project.

• Smart Media Journal
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• v.9 no.3
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• pp.107-115
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• 2020

Recently, BIM has become mandatory in the construction field, research on various use cases is increasing. In particular, when virtual reality technology, one of the core technologies of the 4th industrial revolution, and BIM are combined, it can be used in various fields such as preliminary design review and construction simulation. Until now, however, virtual reality grafting technology is only used as a simple prototype or as a model house. Also, it is difficult to activate virtual construction because it is expensive to produce high-quality virtual reality contents. Therefore, in this paper, in order to increase the utilization and quality of the virtual construction field, a study was conducted to shorten the material mapping time, which takes a lot of time when producing virtual reality contents using BIM. To this end, object properties were assigned to enable material mapping in the BIM model, and materials most used in the construction field were configured, and automated material function development and final tests were conducted that automatically map properties and materials. For the test, 10 models were used and the test was repeated three times, and the productivity improvement of about 50.16% was finally achieved. In the future, we plan to conduct research on physical data weight reduction based on the advanced material mapping automation function and the large-capacity BIM model.

• International Journal of Highway Engineering
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• v.20 no.2
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• pp.19-25
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• 2018

PURPOSES : This purpose of this study is to analyze the effect to autogenous shrinkage of the top-layer material of a two-lift concrete pavement mixing both silica fume and polymer powder. METHODS : The bottom-layer of a two-lift concrete pavement was paved with original portland cement (OPC) with a 20~23 cm thickness. Additionally, the top-layer which is directly exposed to the environment and vehicles was paved with a high-performance concrete (HPC) with a 7~10 cm thickness. These types of pavements can achieve a long service life by reducing joint damage and increasing the abrasion and scaling resistance. In order to integrate the different bottom and top layer materials, autogenous shrinkage tests were performed in this study according to the mixing ratio of silica fume and polymer powder, which are the admixture of the top-layer material. RESULTS : Autogenous shrinkage decreased when polymer powder was used in the mix. Contrary to this, autogenous shrinkage tended to rise with increasing silica fume content. However, the effects were not significant when small amounts of polymer powder were used (3% and 11%). CONCLUSIONS : The durability and compressive strength increase when silica fume is used in the mix. The flexural strength considerably increases and autogenous shrinkage of concrete decreases when polymer powder is used in the mix. As seen from above, the proper use of these materials improves not only durability, but also autogenous shrinkage, leading to better shrinkage crack control in the concrete.

• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.396-401
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• 2013

PURPOSE. The purpose of this in vitro study was to investigate the flexural properties of a recently introduced urethane dimethacrylate denture base material (Eclipse) after being repaired with two different materials. MATERIALS AND METHODS. Two repair groups and a control group consisting of 10 specimens each were generated. The ES group was repaired with auto-polymerizing polymer. The EE group was repaired with the Eclipse. The E group was left intact as a control group. A 3-point bending test device which was set to travel at a crosshead speed of 5 mm/min was used. Specimens were loaded until fracture occurred and the mean displacement, maximum load, flexural modulus and flexural strength values and standard deviations were calculated for each group and the data were statistically analyzed. The results were assessed at a significance level of P<.05. RESULTS. The mean "displacement", "maximum load before fracture", flexural strength" and "flexural modulus" rates of Group E were statistically significant higher than those of Groups ES and EE, but no significant difference (P>.05) was found between the mean values of Group ES and EE. There was a statistically significant positive relation (P<.01) between the displacement and maximum load of Group ES (99.5%), Group EE (94.3%) and Group E (84.4%). CONCLUSION. The more economic and commonly used self-curing acrylic resin can be recommended as an alternative repair material for Eclipse denture bases.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.104-109
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• 2020

Recently, vibration and noise have become an important issue in the auto industry. Asphalt vibration damping pads are used to reduce the noise and vibration of automobile bodies, and asphalt is used for many mass-produced parts due to its simple attachment process and low processing costs. In this study, the self-adhesion of asphalt pads using Joule heating was evaluated. To create the asphalt pad for the experiment, the asphalt pad was molded into a specific thickness by using SGACC material and rubber used in the vehicle body as a main component and a modified resin and filler. The SGACC material was 200 mm in length, 200 mm in width, and 0.7 mm in thickness. The asphalt pad was 200 mm in length, 100 mm in width, and 3 mm in thickness. The equipment was composed of a TR (Transformer) DC254kVA and a TC (Time controller) for a current of up to 20,000 A. The current for the Joule heating was set to 7.0 kA and a 3/1 cycle, for which the adhesion of the asphalt pad over the current flow time was evaluated.