• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.423-423
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• 2010

유기발광소자의 제작 기술이 빠르게 발전함에 따라 디스플레이와 조명 분야에서 많은 응용 가능성을 보여주고 있다. 유기발광소자의 발광효율은 발광층내에서 전자와 정공의 비와 밀접한 관계가 있기 때문에 전자 수송층과 정공 수송층내에서 전하의 이동도를 제어하는 구조에 대한 연구는 매우 중요하다. 본 연구에서는 전자 수송층으로 tris(8-hydroxyquinoline)aluminum ($Alq_3$)와 4,7-diphenyl-1,10-phenanthroline (BPhen)의 다중 이종구조를 사용하여 제작된 녹색 유기발광소자의 전기적 성질과 광학적 성질을 연구하였다. $Alq_3$와 BPhen 다중 이종구조의 위치와 이종구조 개수의 변화에 따라 전자의 변하는 전송특성으로 인하여 변화되는 발광특성을 체계적으로 조사하였다. 유기발광소자의 구동전압은 $Alq_3$/BPhen 이종구조의 수가 증가할수록 증가하는 경향을 보인다. $Alq_3$와 BPhen 내에서 전자의 이동도가 다르기 때문에 $Alq_3$/BPhen 이종계면에 전자가 축적되어 공간전하를 형성하므로 계면에서 내부전계가 형성되어 구동전압이 약간 증가하는 경향을 보인다. 또한 $Alq_3$/BPhen 이종계면에서 축적된 전자들로 인하여 형성된 내부 전계로 인해 저전압에서 누설 정공의 수가 증가하였다. 그러나 다중 이종구조로 된 전자 수송층을 포함한 유기발광소자의 발광 효율은 구동전압이 증가할수록 안정화 되었다. 이는 이종계면의 수가 증가함에 따라 각각의 이종계면에서 축적되는 전자의 양이 감소하기 때문에 고전압에서 효율감소율이 작아졌다. $Alq_3$/BPhen 다중 이종구조를 가진 전자 수송층내에서 전자의 전송 메카니즘에 대한 이해는 유기발광소자의 발광효율이 안정화된 구조를 설계하는데 중요한 실험적 결과를 제공한다.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.51-55
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• 2008

Purpose: To develop the program used in calculating and estimating anamorphic prisms used to construct an anamorphoser. Methods: If there is a program which can show the apex angle and the volume of prism which are decided by the refraction index of anamorphic prisms and the expanding ratio of incident beam, the production of anamorphic prisms can be done accurately. Moreover, it could become a convenient tool to the design and production of whole optical systems using anamorphic prisms. Developing this program, first, we had to induce formulas of prism that decide the apex angle and the arrangement angle of anamorphic prisms with the given refraction index of anamorphic prism and the given expanding ratio of incident beam. Then we programmed them by delphi 6.0 language so that they could be visualized on screen and easily confirmed. Results: We could develop the program used in calculating and estimating anamorphic prisms used to construct an anamorphoser. Conclusions: Judging from the results of applying this developed program to actual business, we could conclude that this program is useful in calculation and production of anamorphic prisms which are used as components of an anamorphoser because this program can offer a lot of accuracy and quickness to producers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.399-402
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• 2004

In the optical drive system, adopting the optical flying-type head (OFH) flying on a removable plastic disk, the flying stability of the small OFH should be carefully considered to ensure the reliability for first surface recording. Additional micro actuators for focus servo are discussed for better interface of optical flying head on thin cover layered plastic disk to eliminate focus error due to the non-uniformity of cover layer thickness and the tolerance of lens assembly. This study gives two simulation results on the flying stability of the OFH. One is the dependence of the flying height and pitch angle variations on the wavelength and amplitude of disk waviness. The other is the flying stability of the slider and suspension system during the dynamic load/unload (U/UL) process.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.149-155
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• 2015

The ECR (Electron Cyclotron Resonance) Ar ion milling was manufactured to fabricate the device of thin film. The ECR ion milling system applied to the device etching operated by a power of 600W, a frequency of 2.45 GHz, and a wavelength of 12.24 cm and transferred by a designed waveguide. In order to match one resonant frequency, a magnetic field of 908 G was applied to a cavity inside of ECR. The Ar gas intruded into a cavity and created the discharged ion beam. The surface of target material was etched by the ion beam having an acceleration voltage of 1000 V. The formed devices with a width of $1{\mu}m{\sim}9{\mu}m$ on the GMR-SV (Giant magnetoresistance-spin valve) multilayer after three major processes such as photo lithography, ion milling, and electrode fabrication were observed by the optical microscope.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.898-905
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• 2018

In this work, infrared targets for a developed hardware-in-the-loop simulation(HILS) system are proposed for a performance test of a dual-sensor imaging seeker equipped with an infrared and a visible sensor that can lock and track for ground and air targets. This integrated system is composed of 100 modules of heat and light sources to simulate various kinds of target and the trajectory of moving targets based on scenarios. It is possible to simulate not only the position, velocity, and direction for these targets but also background clutter and jamming environments. The design and measurement results of an infrared target, such as the HILS system configuration, developed for testing and evaluation of a dual-sensor imaging seeker are described. In the future, it is planned to test the lock-on and tracking performance of an imaging seeker equipped with single or dual sensors dynamically in real time based on a simulation flight scenario in the developed HILS system.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.991-1000
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• 2021

Among non-invasive blood glucose detection technologies, the optical technique is a method that uses light reflection, absorption, and scattering characteristics when passing through a biological medium. It reduces pain or discomfort in measurement and has no risk of infection. So it is becoming a major flow of blood glucose detection research. Among them, near-infrared spectroscopy has a disadvantage in that the complexity increases when analyzing signals detected due to interferences between proteins and acids that share a similar absorption function with blood glucose molecules. In this study, a non-invasive sensor system with multiple near-infrared bands was designed and manufactured to alleviate the deterioration of blood glucose detection function that may occur due to skin absorption of near-infrared rays. A blood survey was conducted to verify the system, and the degree of blood glucose response in the blood was collected as spectral data, and the results of this study were quantitatively verified in terms of correlation between the data and blood glucose.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.305-312
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• 2021

This study examines the damage to the submarine's escape trunk hatch spring through microstructure analysis. The cause of the escape trunk's damage during the submarine's construction and its improvement measures were reviewed. To determine the cause of breakage of the escape trunk spring, samples were taken from the damaged product and analyzed for chemical composition, hardness, and microstructure. In particular, the breakage part of the spring was analyzed in-depth by using a scanning electron microscope to determine the cause of corrosion destruction. Finally, a spring shape design method was proposed through the investigation of the cause of spring breakage. In addition, a newly improved spring was produced by applying a nylon coating with excellent corrosion resistance and abrasion resistance. Applying to an actual submarine trunk hatch revealed that the coating peeling phenomenon due to the contact between the springs is significantly improved when the hatch is opened or closed compared to the existing products.

• Composites Research
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• v.35 no.3
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• pp.182-187
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• 2022

In this paper, the thickness of a multilayer PCB was predicted through an empirical formulation based on the physical properties of the prepreg used in multilayer PCB. Since the thickness of prepreg reduction when manufacturing a PCB due to the physical properties and copper foil residual rate, it is necessary to accurately predict the thickness of the PCB through the thickness empirical formulation. To determine the density of the prepreg, the mass and thickness of the prepreg were measured. To manufacture the CCL, the prepreg and copper foil were laminated using a hot press machine, and the thickness was measured using a microscope and micrometer. An 8-layerd PCB was designed with different circuit densities to measure the change in the thickness with the copper foil residual ratio, and the proposed empirical formulation was verified by comparing the measured thickness with the value obtained using the empirical formulation. As a result, the errors for the CCL and multilayer PCB were 2.56% and 4.48%, respectively, which demonstrated the reliability of the empirical formulation.

• Smart Media Journal
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• v.12 no.3
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• pp.49-59
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• 2023

Optical Camera Communication (OCC), known as the next-generation wireless communication technology, is currently under extensive research. The performance of OCC technology is affected by the communication environment, and various strategies are being studied to improve it. Among them, the most prominent method is applying convolutional neural networks (CNN) to the receiver of OCC using deep learning technology. However, in most studies, CNN is simply used to detect the transmitter. In this paper, we experiment with applying the convolutional neural network not only for transmitter detection but also for the Rx demodulation system. We hypothesize that, since the data images of the OCC system are relatively simple to classify compared to other image datasets, high accuracy results will appear in most CNN models. To prove this hypothesis, we designed and implemented an OCC system to collect data and applied it to 12 different CNN models for experimentation. The experimental results showed that not only high-performance CNN models with many parameters but also lightweight CNN models achieved an accuracy of over 99%. Through this, we confirmed the feasibility of applying the OCC system in real-time on mobile devices such as smartphones.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.197-202
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• 2023

Calcium fluoride (CaF₂) single crystal is applied to numerous industrial applications, especially for optical uses. To have excellent optical transmission properties, however, CaF₂ crystals should be carefully fabricated through liquid-phase crystal growth techniques. In this study, as one of the early stage research activities to grow CaF₂ crystals with a good transmittance at the ultraviolet wavelength range, computational thermodynamic models were provided to deepen the understanding of the crystal growing processes of CaF₂ under various conditions. To remove point defects and oxygen impurities in the grown CaF₂ crystals, the system was thermodynamically evaluated to get optimal process conditions. From the reviews of previous experimental studies, computational thermodynamic approaches were found to be an effective and powerful tool to understand the meaning of the crystal growth processes and to obtain optimal process conditions.