• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.142-143
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• 2007

나노미터 크기의 동심원 패턴이 형성된 도광판을 설계하기 위한 전산모사를 수행한다. 광원은 LED 1개를 사용하였으며 PMMA 도광판 재질의 파장에 따른 빛의 흡수 현상을 고려하였다. 도광판 위치에 따른 투과광선의 세기 분포, 투과광선의 투과각도 분포 및 편광에 따라 투과광선의 세기가 어떻게 달라지는지 살펴보았다.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.652-656
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• 2011

Thin film of titania nanotubes(TNT) and titania nanofilms(TNF) was fabricated by anodizing for the study of the photo-catalytic reaction(PC) and photoelectrocatalytic reaction(PEC). Removal efficiency of methylene blue was investigated by UV radiation on the TNT coated titanium plate. Removal efficiency was increased with longer TNT length. Degradation efficiency of the PEC reaction was less sensitive than that of PC reaction. And Effect of TNT length is relatively small. Titania nanofilms(TNF) showed low efficiency than TNT. The efficiency drop of PC was larger than that of PEC.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.703-703
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• 2013

다이아몬드상 탄소 박막(Diamond-like carbon, DLC) 박막은 낮은 마찰 계수, 높은 내마모성, 화학적 안정성, 적외선 영역에서의 높은 투과율 등의 장점을 바탕으로 MEMS (Micro-Electro Mechanical System) 소자와 MMAs (Moving Mechanical Assemblies)의 고체윤활코팅, 마그네틱 미디어와 하드디스크의 슬라이딩 표면 등 다양한 분야에 코팅소재로써 응용되어왔다 [1,2]. 현재 전기철도용 집전판은 마찰이 적고 전도성을 지니는 카본 소재로 구성되어 있다. 그러나 그 마모 비율이 너무 심하여 이를 개선할 수 있는 방안으로 고경도 저마찰력을 지니는 DLC 박막을 코팅 소재로써 제안하고자 한다. 그러나 기존에 DLC 박막은 절연특성이 매우 우수하기 때문에 기존에 전도성을 지니는 카본 집전판에 적용하기에는 어려움이 따른다. 따라서 DLC 박막 내에 실리콘(Si) 또는 금속(Metal)을 첨가시키거나, 금속 중간층을 포함시켜 전기적으로 전도특성을 향상시키는 방안이 제시되고 있으며, 본 연구에서는 DLC 박막과 유사하게 우수한 경도특성을 지니고, 낮은 마찰계수등을 지니는 비정질 탄소박막을 연구하여 카본 집전판에 코팅하고자하며, 특히 비정질 탄소박막에 금속 Ti를 도핑하여 집전판과의 접착력과 전기적 전도 특성을 향상시키고자 한다. Ti가 도핑된 탄소박막(TiC) 박막은 비대칭 마그네트론 스퍼터링(unbalanced magnetron sputtering; UBMS) 시스템을 이용하여 제작하였으며, 스퍼터링 조건 중 기판에 인가되어지는 기판온도에 따라 변화되어지는 TiC 박막의 트라이볼로지(Tribology) 특성을 고찰하고자 하였다. 증착시 기판온도의 증가는 TiC 박막의 경도, 마찰계수 특성등 트라이볼로지 특성을 향상시켰으며, 전기적 전도 특성을 향상시켰다. 이러한 결과는 스퍼터링 방법에 의해 증착되어진 TiC 박막내에 존재하는 sp2 결합과 관계가 있음을 확인할 수 있으며, 트라이 볼로지 특성은 TiC 박막내에 sp2 탄소결합의 비율 증가와 관련되어졌다. 특히 sp2 탄소결합은 TiC 박막 증착시 증가된 기판온도와 밀접한 관계가 있으며 기판온도의 증가에 따라 나노결정 클러스터의 크기와 수의 변화와 밀접한 관계가 있음을 확인하였다. 결국 기판온도는 TiC 박막의 트라이볼로지 특성을 향상시켰으며, 전기적 특성 또한 향상시켜 전기철도 집전판에 응용을 위한 소재로 평가할 수 있다.

• Korean Journal of Optics and Photonics
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• v.21 no.2
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• pp.53-60
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• 2010

An integrated light guide plate (LGP) was designed for liquid crystal displays (LCD) without using prism and diffuser sheets. The integrated LGP is textured with micro-patterns on both the top and bottom surfaces. The textures effectively substitute for a single prism-sheet and a diffuser sheet in LCD displays without decreasing the brightness and uniformity. A LCD display with our integrated light guide is simulated to give average luminance of 4560 cd/$m^2$, luminance uniformity of 83% horizontal viewing angle $60^{\circ}$ and vertical viewing angle $56^{\circ}$. Therefore an ultra thin (slim) back light unit can be constructed with fewer optical sheets, which reduces the manufacturing cost and so improves price competitiveness.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.91-91
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• 2015

반도체 공정의 발전에 의해 최근 생산되는 메모리 등은 십 수 나노미터까지 좁아진 선 폭을 갖게 되었다. 이러한 이유로, 기존에는 큰 문제를 발생시키지 않던 나노미터 영역의 입자들이 박막 증착 공정과 같은 반도체 제조공정 수율을 저감시키게 되었다. 따라서 오염입자의 유입을 막거나 제어하기 위해 transmission electron microscopy (TEM)나 scanning electron microscopy (SEM)과 같은 전자현미경을 활용한 비 실시간 입자 측정 방법 및 광원을 이용하는 in-situ particle monitor (ISPM) 및 전기적 이동도를 이용한 scanning mobility particle sizer (SMPS) 등 다양한 원리를 이용한 실시간 입자 측정방법이 현재 사용중에 있다. 이 중 진공 내 입자의 수농도를 측정하기 위해 개발된 particle beam mass spectrometer (PBMS) 기술은 박막 증착 공정 등 chemical vapor deposition (CVD) 방법을 이용하는 진공공정에서 활용 가능하여 개발이 진행되어 왔다. 본 연구에서는 PBMS의 한계점인 입자 밀도, 형상 등의 특성분석이 용이하도록 PBMS와 scanning electron microscopy (SEM), 그리고 energy dispersive spectroscopy (EDS) 기술을 결합하여 입자의 직경별 개수농도, 각 입자의 형상 및 성분을 함께 측정 가능하도록 하였다. 협소한 반도체 제조공정 내부 공간에 적용 가능하도록 기존 PBMS 대비 크기 또한 소형화 하였다. 각 구성요소인 공기역학 집속렌즈, electron gun, 편향판, 그리고 패러데이 컵의 설치 및 물리적인 교정을 진행한 후 입자발생장치를 통해 발생시킨 sodium chloride 입자를 상압 입자 측정 및 분류장치인 SMPS 장치를 이용하여 크기별로 분류시켜 압력차를 통해 PBMS로 유입시켜 측정을 진행하였다. 나노입자의 입경분포, 형상 및 성분을 측정결과를 토대로 장치의 측정정확도를 교정하였다. 교정된 장치를 이용하여 실제 박막 증착공정 챔버의 배기라인에서 발생하는 입자의 수농도, 형상 및 성분의 복합특성 측정이 가능하였으며, 최종적으로 실제 공정에 적용가능하도록 장치 교정을 완료하였다.

• Composites Research
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• v.19 no.5
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• pp.28-33
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• 2006

In this paper, we have studied the complex permittivities and their influence on the design of microwave absorbers of E-glass fabric/epoxy composite laminates containing three different types of carbon-based nano conductive fillers such as carbon black (CB), carbon nano fiber (CNF) and multi-wall nano tube (MWNT). The measurements were performed fur permittivities at the frequency band of 0.5 GHz$\sim$18.0 GHz using a vector network analyzer with a 7 mm coaxial air line. The experimental results show that the complex permittivities of the composites depend strongly on the natures and concentrations of the conductive fillers. The real and imaginary parts of the complex permittivities of the composites were proportional to the filler concentrations. But, depending on the types of fillers and frequency band, the increasing rates of the real and imaginary parts with respect to the filler concentrations were all different. These different rates can have an effect on the thickness in designing the single layer microwave absorbers. The effect of the different rates at 10 GHz was examined by using Cole-Cole plot; the plot is composed of a single layer absorber solution line and measured permittivities from these three types of composites. Single layer absorbers of 3 different thicknesses using carbon nano materials were fabricated and the -10 dB band of absorbing performances were all about 3 GHz.

• Journal of Broadcast Engineering
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• v.26 no.4
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• pp.453-462
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• 2021

A lot of license plate data is required for car number recognition. License plate data needs to be balanced from past license plates to the latest license plates. However, it is difficult to obtain data from the actual past license plate to the latest ones. In order to solve this problem, a license plate recognition study through deep learning is being conducted by creating a synthetic license plates. Since the synthetic data have differences from real data, and various data augmentation techniques are used to solve these problems. Existing data augmentation simply used methods such as brightness, rotation, affine transformation, blur, and noise. In this paper, we apply a style transformation method that transforms synthetic data into real-world data styles with data augmentation methods. In addition, real license plate data are noisy when it is captured from a distance and under the dark environment. If we simply recognize characters with input data, chances of misrecognition are high. To improve character recognition, in this paper, we applied the DeblurGANv2 method as a quality improvement method for character recognition, increasing the accuracy of license plate recognition. The method of deep learning for license plate detection and license plate number recognition used YOLO-V5. To determine the performance of the synthetic license plate data, we construct a test set by collecting our own secured license plates. License plate detection without style conversion recorded 0.614 mAP. As a result of applying the style transformation, we confirm that the license plate detection performance was improved by recording 0.679mAP. In addition, the successul detection rate without image enhancement was 0.872, and the detection rate was 0.915 after image enhancement, confirming that the performance improved.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.846-850
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• 2011

Nanocomposite anodes for rechargeable lithium battery are prepared by mixing tin and nickel nanoparticles via wet method and their electrochemical properties are examined. The Sn-Ni nanocomposite anode shows a maximum discharge capacity of 700 mAh $g^{-1}$ at the first cycle but very poor cycle performance. This means that the electrode porosity and the Ni component formed by the simple mixing of nanoparticles no longer play the role of buffering the volume expansion/contraction of Sn component during charge-discharge. To solve the cycle performance problem, a novel nanostructured Sn-Ni anode should be designed and tested.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.39-45
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• 2009

Statement of problem: Recently precalcification treatment has been studied to shorten the period of the implant. Purpose: This study was performed to evaluate the effect of precalcification treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy. Material and methods: Specimens of $20{\times}10{\times}2\;mm$ in dimensions were polished sequentially from #220 to #1000 SiC paper, ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. The nanotubular layer was processed by electrochemical anodic oxidation in electrolytes containing 0.5 M $Na_2SO_4$ and 1.0 wt% NaF. Anodization was carried out using a regulated DC power supply (Kwangduck FA, Korea) at a potential of 20 V and current density of $30\;㎃/cm_2$ for 2 hours. Specimens were heat-treated at $600^{\circ}C$ for 2 hours to crystallize the amorphous $TiO_2$ nanotubes, and precalcified by soaking in $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. To evaluate the bioactivity of the precalcified $TiO_2$ nanotube layer, hydroxyapatite formation was investigated in a Hanks' balanced salts solution with pH 7.4 at $36.5^{\circ}C$ for 2 weeks. Results: Vertically oriented amorphous $TiO_2$ nanotubes of diameters 48.0 - 65.0 ㎚ were fabricated by anodizing treatment at 20 V for 2 hours in an 0.5 M $Na_2SO_4$ and 1.0 NaF solution. $TiO_2$ nanotubes were composed with strong anatase peak with presence of rutile peak after heat treatment at $600^{\circ}C$. The surface reactivity of $TiO_2$ nanotubes in SBF solution was enhanced by precalcification treatment in 0.5 M $Na_2HPO_4$ solution for 24 hours and then in saturated $Ca(OH)_2$ solution for 5 hours. The immersion in Hank's solution for 2 weeks showed that the intensity of $TiO_2$ rutile peak increased but the surface reactivity decreased by heat treatment at $600^{\circ}C$. Conclusion: This study shows that the precalcified treatment of $TiO_2$ Nanotube formed on Ti-6Al-4V Alloy enhances the surface reactivity.

• Composites Research
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• v.30 no.4
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• pp.235-240
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• 2017

Animal glue, a water-soluble adhesive, has been used historically for high-performance traditional furniture despite the disadvantage of weakness against moisture. Many scientists studied the ways to improve water resistance of animal glue. Improvements on the interfacial, thermal, and water resistance properties of wood sandwich composites (WSC) was studied with carbon nanotube (CNT) wt% in animal glue. Real-time temperature of WSC was measured after WSC was heated with increasing CNT wt%. Lap shear test was performed to determine the interfacial properties of wood and animal glue with CNTs. Water resistance properties of animal glue were determined by lap shear test using specimens dipped in water and the results were compared with the dry case. Hydrophobicity of animal glue by static contact angle was correlated with the variation of lap shear test. Interfacial, thermal, and water resistance properties for animal glue were improved with properly added CNTs.