• Composites Research
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• v.16 no.5
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• pp.39-44
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• 2003

Embedding viscoelastic-damping materials into composites can greatly increase the damping properties of composite structures. Usually viscoelastic-damping materials behave isotropically so that their damping properties are the same in all directions. In these days, there is a desire to develop viscoelastic-damping materials that behave orthotropically so that damping properties vary with material orientation. These orthotropic damping materials can be made by embedding rows of thin wires within the viscoelastic materials. These wires add significant directional stiffness to the damping materials. where the stiffness variation with wire orientation follows classical lamination theory. In this paper, the loss factor of composite laminate was evaluated based on Ni and Adams' theory. To investigate the effect of directional damping material, the low-velociy impact response analysis was also performed. The present analysis results show that directional damping material has a great influence on vibration and damping characteristic of composite laminate.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.1067-1070
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• 2011

We have demonstrated that solution-based fabrication of NiO films as HTL can be used for the construction of IOSCs. Type of solvent of NiO-solution, and annealing procedure of the active layers were optimized for obtaining a PCE of 3% of IOSC. The photovoltaic performance of NiO-based device is comparable to that of the same type of solar cell using PEDT:PSS instead of NiO. These solution-based processes can be a promising method for a mass production OSCs under ambient condition.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.366-379
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• 2017

Nanostructured materials have attracted considerable research interest over the recent decades because of their potential applications in nanoengineering and nanotechnology. On the other hand, the developments in nanotechnology are strongly dependent on the availability of new materials with novel and engineered morphologies. Among the novel nanomaterials reported thus far, composite nanofibers (NFs) have attracted considerable attention in recent years. In particular, metal oxide NFs have great potential for the development of gas sensors. Highly sensitive and selective gas sensors can be developed by using composite NFs owing to their large surface area and abundance of grain boundaries. In composite NFs, gas sensing properties can be enhanced greatly by tailoring the conduction channel and surface properties by compositional modifications using the synergistic effects of different materials and forming heterointerfaces. This review focuses on the gas sensing properties of composite NFs synthesized by an electrospinning (ES) method. The synthesis of the composite NFs by the ES method and the sensing mechanisms involved in different types of composite NFs are presented along with the future perspectives of composite NFs.

• Nuclear Engineering and Technology
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• v.38 no.7
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• pp.619-638
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• 2006

Low temperature irradiation can significantly harden metallic materials and often lead to strain localization and ductility loss in deformation. This paper provides a review on the radiation effects on the deformation of metallic materials, focusing on microscopic and macroscopic strain localization phenomena. The types of microscopic strain localization often observed in irradiated materials are dislocation channeling and deformation twinning, in which dislocation glides are evenly distributed and well confined in the narrow bands, usually a fraction of a micron wide. Dislocation channeling is a common strain localization mechanism observed virtually in all irradiated metallic materials with ductility, while deformation twinning is an alternative localization mechanism occurring only in low stacking fault energy(SFE) materials. In some high stacking fault energy materials where cross slip is easy, curved and widening channels can be formed depending on dose and stress state. Irradiation also prompts macroscopic strain localization (or plastic instability). It is shown that the plastic instability stress and true fracture stress are nearly independent of irradiation dose if there is no radiation-induced phase change or embrittlement. A newly proposed plastic Instability criterion is that the metals after irradiation show necking at yield when the yield stress exceeds the dose-independent plastic instability stress. There is no evident relationship between the microscopic and macroscopic strain localizations; which is explained by the long-range back-stress hardening. It is proposed that the microscopic strain localization is a generalized phenomenon occurring at high stress.

• Journal of Information Science Theory and Practice
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• v.9 no.4
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• pp.1-14
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• 2021

Library communities face many problems and limitations in describing alternative format materials based on the traditional MAchine Readable Cataloging (MARC) structure. To address these problems, this research proposes an XML-based descriptive metadata framework that establishes general but fundamental bibliographic aspects of various alternative format materials by providing core elements that are essential in describing these materials. Different from existing bibliographic structures, the proposed metadata framework can represent a fundamental descriptive structure by establishing four upper-level categories, 17 core elements, and 10 sub-elements in a hierarchical structure optimized to alternative format materials. By using this principal descriptive structure, the proposed metadata framework can guide different institutions in the creation of bibliographic records for these materials in a consistent way. It is also expected to address the difficulties in describing alternative format materials in library communities and enhance the information accessibility of individuals with various types of disabilities. In addition, the proposed metadata framework is an alternative approach which functions as a mediator between heterogeneous characteristics of alternative format materials and the existing bibliographic structures in library communities.

• Steel and Composite Structures
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• v.50 no.2
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• pp.237-247
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• 2024

Research on interfacial crack formation in orthotropic bi-materials has experienced a notable increase in recent years, driven by growing concerns about structural integrity and reliability. The existence of a crack at the interface of bi-materials has a substantial impact on mechanical strength and can ultimately lead to fracture. The primary objective of this article is to introduce a comprehensive analytical model and establish stress relationships for investigating interfacial crack between two non-identical orthotropic materials with desired crack-fiber angles. In this paper, we present the application of the Interfacial Maximum Tangential Stress (IMTS) criterion, in combination with the Reinforcement Isotropic Solid (RIS) model, to investigate the behavior of interfacial cracks in orthotropic bi-materials under mixed-mode I/II loading conditions. We analytically characterize the stress state at the interfacial crack tip using both Stress Intensity Factors (SIFs) and the T-stress term. Orthotropic materials, due to their anisotropic nature, can exhibit complex crack tip stress fields, making it challenging to predict crack initiation behavior. The secondary objective of this study is to employ the IMTS criterion to predict the crack initiation angle and explore the notable impact of the T-stress term on fracture behavior. Furthermore, we validate the effectiveness of our approach in evaluating Fracture Limit Curves (FLCs) for interfacial cracks in orthotropic bi-materials by comparing our FLCs with relevant experimental data from existing literature.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.513-520
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• 1999

20 million tons of coal ash has been produced in Korea annually. This causes the environmental problems and the cost of land for ash pond. However the amount of coal ash for recycling is small because of the low level of recycling technology and the ignorance. As the coal ash has the significant engineering properties, it can be utilized as soft ground stabilizer, backfill materials and so forth. The purpose of this paper is to summarize some of the recycling methods of coal ash. One is structural backfill materials, the other is flowable fill. Optimal mixture ratio(fly ash : bottom ash) is determined for structural backfill materials and the model test is performed. The model test accompanied with physical tests were executed for identifying that the flowable fly ash can be used as fill materials such as trench back filling.

• Natural Product Sciences
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• v.2 no.2
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• pp.137-142
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• 1996

This paper gives a description about the germination inhibition of American ginseng (Panax quinquefolium L.) seed coat. The existence of seed coat is one of the inhibitory factors which inhibit the embryo growth, particularly during the morphological after-ripening stage. The seed coat can obstruct the water absorption at the beginning of seed stratification, but it can not threaten seed germination. The inhibition of seed coat is not caused by the mechanical fetter neither. However, before splitting the seed coat, the inhibition of seed coat comes from both air-tight character and inhibitors, and after splitting the seed coat, the inhibition may come mainly from the inhibitors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.198-201
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• 1995

Carbons are the materials which are known to be usable at highest temperature in existing materials and are being increased their mechanical Properties to 2000$^{\circ}C$. They have many advantageous characteristics such as electrical and thereat conductivity. But, inspire of their properties, this materials have covalant bonding that strong1y link their atoms. the covalant bondings are too strong to occur atomic diffusions or shirinkages during the sintering. because of this sintering mechanism, carbon materials must be produced by using some binders. To obtain a good carton material, it is important that the function of binders. And to obtain a good binder, it reqired the additive which can improve the properties of the binder, so called curing agent. In this study, we make a curing agent that can improve the properties of binders to evaluate the yield of carbon from binders and to shirink the substrate. and compared the carbon materials treated with the binder containing the curing agent to that treated with common binder.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.265-266
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• 2006

It was well known that thermopile was quiet a competent sensor using to probe the temperature of "hot point" where the temperature can be off the temperature-limitation for normal operation of the main electrical power equipment. In the present work, we aimed for developing new Ge-thermopile materials which can be using a non-contact temperature sensors at various hot-point of the power equipment and evaluation of its output property. As a results of the present works, a new thermopile which were composed Ga-poded p-type and Sb-doped n-type in Ge-semiconductor were designed and manufactured by MBE(Molecular Beam Epitaxy) process and showed superior sensitivity at room temperature.