• 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.

• Laser Solutions
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• v.15 no.4
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• pp.6-11
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• 2012

Laser beam can be either absorbed or scattered in porous ceramic material and its optical characteristics need to be understood. Electro-magnetic multiphysics software was used to simulate and understand the actual scattering phenomena in porous materials. 785nm femtosecond laser was irradiated on the surface of ceramic material and strong scattering occurred in drilling process. The computer results showed the scattering and absorption phenomena of Aluminum oxide were a mixture of dielectric and metallic material. The computer simulation showed the laser beam was almost extinct at the aspect rate of 5 approximately.

• Transactions of Materials Processing
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• v.9 no.1
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• pp.59-65
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• 2000

Most studies of failure analysis in ductile metals have been based on the classical plasticity theory using the local constitutive relations. These frequently yields a physically unrealistic solution, in which a numerical prediction of the onset of a deformation localization shows an inherent mesh-size sensitivity. A one way to remedy the spurious mesh sensitivity resulted in the unreasonable results is to incorporate the non-local plasticity into the simulation model, which introduce an internal (material) length-scale parameter into the classical constitutive relations. In this paper, a non-local version of the modified Gurson constitutive relation has been introduced into the finite element formulation of the simulation for plane strain compression of the visco elastic-plastic void material. By introducing the non-local constitutive relations we could successfully removed the inherent mesh-size sensitivity for the prediction of the deformation localization. The effects of non-local constitutive relation are discussed in terms of the load-stroke curve and the strain distributions accross the shear band.

• Journal of Radiation Protection and Research
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• v.48 no.4
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• pp.167-174
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• 2023

Background: A nondestructive test is commonly used to inspect the surface defects and internal structure of an object without any physical damage. X-rays generated from an electron accelerator or a tube are one of the methods used for nondestructive testing. The high penetration of X-rays through materials with low atomic numbers makes it difficult to discriminate between these materials using X-ray imaging. The interaction characteristics of neutrons with materials can supplement the limitations of X-ray imaging in material discrimination. Materials and Methods: The radiation image acquisition process for air-cargo security inspection equipment using X-rays and neutrons was simulated using a GEometry ANd Tracking (Geant4) simulation toolkit. Radiation images of phantoms composed of 13 materials were obtained, and the R-value, representing the attenuation ratio of neutrons and gamma rays in a material, was calculated from these images. Results and Discussion: The R-values were calculated from the simulated X-ray and neutron images for each phantom and compared with those obtained in the experiments. The R-values obtained from the experiments were higher than those obtained from the simulations. The difference can be due to the following two causes. The first reason is that there are various facilities or equipment in the experimental environment that scatter neutrons, unlike the simulation. The other is the difference in the neutron signal processing. In the simulation, the neutron signal is the sum of the number of neutrons entering the detector. However, in the experiment, the neutron signal was obtained by superimposing the intensities of the neutron signals. Neutron detectors also detect gamma rays, and the neutron signal cannot be clearly distinguished in the process of separating the two types of radiation. Despite these differences, the two results showed similar trends and the viability of using simulation-based radiation images, particularly in the field of security screening. With further research, the simulation-based radiation images can replace ones from experiments and be used in the related fields. Conclusion: The Korea Atomic Energy Research Institute has developed air-cargo security inspection equipment using neutrons and X-rays. Using this equipment, radiation images and R-values for various materials were obtained. The equipment was reconstructed, and the R-values were obtained for 13 materials using the Geant4 simulation toolkit. The R-values calculated by experiment and simulation show similar trends. Therefore, we confirmed the feasibility of using the simulation-based radiation image.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.41-44
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• 2001

In this paper, we explain briefly polysilicon guard layer in a simple 3-D structure. Simulation was performed extensively to see interference and characterize the role of the polysilicon guard layer. Especially, we performed extensively S-parameter simulation to analysis the signal interference. The interference was characterized in terms of oxide thickness, polysilicon doping concentration, thickness, number of contact of polysilicon guard, and metal guard size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.313-316
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• 1995

In this study, in case the lead sheath of XLPE cable (radius : 15cm, inner conductor radius : 5cm, insulation paper raidius : 6cm, dc voltage : 1MV) is harmed, so that breakdown process by inhomogeneous eletric field is simulated with Finite Element Method. The result of simulation showed that defect of lead sheath layer caused breakdown.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.328-331
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• 2001

Color simulation on a portable colorimeter was performed to distinguish quantitatively a chromaticity coordinates on a color guide of a urine strips by using the spectral power distribution of chip LED, the spectral reflectance of printed objects, and the spectral sensitivity of photodiode. The CIE tristimulus values and chromaticity coordinates realized by a colorimeter were modified to be conformable with real color reactions. Experimental results showed a real color in comparison with those obtained by Colorimeter CM2C(Color Savvy).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.162-162
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• 2010

In this study, optical analysis for 100W LED safety street lighting was conducted. Experimental research on such single LED was the first undertaken. simulation modeling based on optical properties of single LED has compared single LED product also designed 100W simulation modeling has compared average road illuminance with Korean Industrial Standards for LED safety street lighting(KS C7658:2009). 100W safety street lighting (model: CE180-ST-OS) designed by simulation has been also compared between product and 100W simulation modeling, and error rates have showed average 5.6[%]. Designed 100W LED safety street lighting base on simulation modeling was proven by comparison experiments. Through the simulations and the corresponding analysis, it was found that the tested 100W LED safety street lamp had reasonable performance. Design method for LED safety Street lamps have been summarized, based on the optical analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2305-2310
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• 2011

This paper describes a design of dual band balanced amplifier using a lefted handed meta-material transmission line structure for high frequency application. Meta-material transmission lines have been known to have dual band frequency responses. A dual band branch line hybrid coupler is designed using the meta-material transmission lines, and measured at first. Two identical dual band amplifiers are also designed, built and tested using the same meta-material transmission structure. The proposed dual band balanced amplifier is composed of those dual band branch line hybrid coupler and amplifiers. In order to suggest an design example, a prototype of dual band balanced amplifier is built and measured at the dual frequencies, 1800MHz($f_1$) and 2300MHz($f_2$). The simulation and measurement show that the fabricated balanced amplifier operates well at the desired dual frequencies bands with the gain of 11.12dB and 17.67dB at $f_1$ and $f_2$, respectively, with a good agreement with the simulation results.

• Transactions of Materials Processing
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• v.4 no.1
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• pp.9-16
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• 1995

Model material technique, which requires only the small space of experimental set-up and low cost for experiment, is used to estimate the deformed profile and the forging load in rotary forging. The materials and working conditions are determined to satisfy the similitude conditions between the model test and the prototype test. The model material of the so-called plasticine and the mild steel are chosen as specimens, and they represent almost the same value of strain gardening exponent in the stress-strain relationship. Lubricant in the model test is also carefully selected so that it gives the same frictional conditions at the tool-specimen interface. Experiments for two kinds of specimens are carried out in each testing equipment at room temperatue. From the experiments the deformed dimensions and the forging loads are measured and compared with each other by using the simulation coefficients. It is shown that there are good agreements between the model test and the prototype test. Finally, for verifying the availability of the model material technique this mathod is applied to forging of bevel gear product. the good result is obained which can demonstrate that the model material technique is very efficent for estimating or developing a new process.