• International Journal of Precision Engineering and Manufacturing
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• v.7 no.2
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• pp.52-55
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• 2006

The OLEDs(Organic Light-Emitting Diodes) structure organizes the bottom layer using glass, ITO(indium thin oxide), hole injection layer, hole transport layer, emitting material layer, electron transport layer, electron injection layer and cathode using metal. OLED has various advantages. OLEDs research has been divided into structural side and emitting material side. The amount of emitting light and luminescence efficiency has been improved by continuing effort for emitting material layer. The emitting light mechanism of OLEDs consists of electrons and holes injected from cathode and anode recombination in emitting material layer. The mobilities of injected electrons and holes are different. The mobility of holes is faster than that of electrons. In order to get high luminescence efficiency by recombine electrons and holes, the balance of their mobility must be set. The more complex thin film structure of OLED becomes, the more understanding about physical phenomenon in each interface is needed. This paper observed what the thickness change of hole transport layer has an affection through the below experiments. Moreover, this paper uses numerical analysis about carrier transport layer thickness change on the basis of these experimental results that agree with simulation results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.28-37
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• 2019

Due to their flexible tailoring qualities, composites have become fascinating materials for structural engineers. While the research area of fiber-reinforced composite materials was previously limited to synthetic materials, natural fibers have recently become the primary research focus as the best alternative to artificial fibers. The natural fibers are eco-friendly and relatively cheaper than synthetic fibers. The main concern of current research into natural fiber-reinforced composites is the prediction and enhancement of the effective material properties. In the present work, finite element analysis is used with a numerical homogenization approach to determine the effective material properties of jute fiber-reinforced epoxy composites with various volume fractions of fiber. The finite element analysis results for the jute fiber-reinforced epoxy composite are then compared with several well-known analytical models.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.11
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• pp.95-99
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• 2008

Applications of composite materials in various engineering fields have been extended significantly. For being useful composite materials, we could modify the rigidity and strength characteristics of composite material according to structures and material direction. In this study, CFRP, which has been widely used in space leisure and general structural applications due to the weight, elasticity coefficient, high fatigue strength and lower thermal transformation ect, was selected. As the CFRP is an anisotropic material whose mechanical properties change with its stacking sequence or angle, special attention was given to the effects of the fiber orientation angle on the bending characteristics of CFRP fiat and CFEP square members. It's different on the each result of strength and rigidity of CFRP flat and CFRP square members.

• Journal of Welding and Joining
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• v.31 no.5
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• pp.41-46
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• 2013

Different microstructures in the weld zone of a metal structure such as a fusion zone or heat affected zone are formed as compared to the parent material. Thus, the mechanical properties in the weld zone are different from those in the parent material. As the basic data for reliably understanding the structural characteristics of a welded PCHE specimen to be made of Alloy 617, the mechanical properties in the weld zone and parent material for a Alloy 617 plate are measured using an instrumented indentation technique in this study.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.04a
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• pp.241-244
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• 2008

This study focused on the checking of design guideline using concept of reference plane as a promoting tool in order to apply to practical affair in relation to material standardization in housing build. For this purpose, we above all defined the role of reference plane. After establishing structural type can correspond to planning module of building components and coordination condition, we did exemplicated the sub-detail of building components which be to detach according to design method using the concept of reference plane that be complexed with spacial territory and replace cycle of building component or material.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.186-187
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• 2019

In modern times, due to the centralized urban structure, the interval between buildings is narrow and the increase of the heat island phenomenon due to the accumulation of the structure is becoming a social problem. In order to solve these problems, various materials for reducing the surface temperature of buildings are under study. Particularly, in the case of a wall part which is a part directly affected by the outside air of the building, it is a main structural part for determining the room temperature. The purpose of this study was to develop a material that can improve the thermal environment performance of the building by evaluating the temperature control performance of the exterior finishing material using the heat reflecting material as a method for controlling the temperature of the outer wall finishing material.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1121-1127
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• 2014

The design, synthesis, and structural characterization of two new palladium complexes based on Schiff base ligands is reported; $[Pd(L1)_2]$ (1) and $[Pd(L2)_2]$ (2), [HL1 = 2-((E)-(2,6-diethylphenylimino)methyl)-4,6-dibromophenol, L2 = (E)-N-benzylidene-2,6-diethylbenzenamine], which are obtained by functionalizing Schiff base ligands with or without electron-withdrawing groups. Both compounds are mononuclear structures. Comparisons are made to the compounds 1 and 2 to analyze and understand the effect of electron-withdrawing groups. Antibacterial activity studies indicate the electron-withdrawing groups on Schiff base ligands enhance antibacterial activity. Catalytic activity, however, is reduced due to the enhanced steric-hindrance of the electron-withdrawing groups. Electronic absorption and emission properties of HL1, L2, 1 and 2 are also reported.

• Structural Engineering and Mechanics
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• v.40 no.1
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• pp.49-64
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• 2011

An analytical method is presented to investigate electromagnetothermoelastic behaviors of a hollow sphere composed of functionally graded piezoelectric material (FGPM), placed in a uniform magnetic field, subjected to electric, thermal and mechanical loads. For the case that material properties obey an identical power law in the radial direction of the FGPM hollow sphere, exact solutions for electric displacement, stresses, electric potential and perturbation of magnetic field vector in the FGPM hollow sphere are determined by using the infinitesimal theory of electromagnetothermoelasticity. Some useful discussion and numerical examples are presented to show the significant influence of material inhomogeneity. The aim of this research is to understand the effect of composition on electromagnetothermoelastic stresses and to design optimum FGPM hollow spheres.

• Steel and Composite Structures
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• v.27 no.2
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• pp.177-184
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• 2018

This study contributes to evaluate multiphase topology optimization design of plate-like structures on elastic foundations by using classic plate theory. Multi-material optimal topology and shape are produced as an alternative to provide reasonable material assignments based on stress distributions. Multi-material topology optimization problem is solved through an alternative active-phase algorithm with Gauss-Seidel version as an optimization model of optimality criteria. Stiffness and adjoint sensitivity formulations linked to thin plate potential strain energy are derived in terms of multiphase design variables and Winkler-Pasternak parameters considering elastic foundation to apply to the current topology optimization. Numerical examples verify efficiency and diversity of the present topology optimization method of elastic thin plates depending on multiple materials and Winkler-Pasternak parameters with the same amount of volume fraction and total structural volume.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.462-467
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• 2004

In order to determine the most suitable material system which can achieve the lightweight design and fulfill the design requirements of carbody structures of Korean Tilting Train eXpress (TTX), aluminum carbody, composite carbody, and hybrid carbody combined with aluminum and composite structures were considered in present study. The finite-element analysis was used to verity the design requirements of the TTX carbody structures with the material system being considered in the design stages. The stresses in the carbody structures and deflections of underframe against static load cases were checked as design criteria. The results show that the hybrid carbody structures are beneficial with regard to weight savings and structural integrity when compared to aluminum and composite carbody structures.