• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.194-201
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• 2004

Optical fibers are indispensable fer optical communication systems that transmit large volumes of data at high speed. But the aligning technology under the sub-micron accuracy is required for the precise axis adjustment and connection. For the purpose of precise alignment of the optical arrays, in this research, we have developed the 12-axis(with 8 automated axis and 4 manual axis) automatic optical fiber alignment system including the image processing-based searching system, the automatic loading system using the robot and the suction toot and the automatic UV bonding system. In order to obtain the sub-micron alignment accuracy, two 4-axis PC-based motion controllers and the two 50nm resolution 6-aixs micro-stage actuated by micro stepping motors are adopted. The fiber aligning procedure consists of two steps. Firstly, the optical wave guide and an input optical array are aligned by the 6-axis input micro-stage with the IR camera. The image processing technique is introduced to reduce primary manual aligning time and result in achieving the 50% decrease of aligning time. Secondly, the IR camera is replaced by the output micro-stage and a wave guide and two optical arrays are aligned simultaneously before the laser power intensity delivered to the optical powermeter reached the threshold value. When the aligning procedure is finished, the wave guide and arrays are W bonded. The automatic loading/unloading system is also introduced and the entire wave guide handing time is reduced significantly compared to the former commercial aligning system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.86-91
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• 2021

Recently, functional clothes that can reduce deposition and/or penetration of fine dust have been developed. However, there are no methods to quantitatively evaluate the performance of these clothes. In this study, we developed a method to contaminate a fabric using fine dust and established an approach to quantitatively assess the degree of particle contamination on the fabric surface. Silicate powder was chosen as the particle to simulate fine dust because silicate particles are fluorescent under UV light; therefore, they can be distinguished from any color of non-fluorescent fabric surface. A camera with a high-resolution lens system was used to scan the surface of the contaminated fabric surface, and the degree of particle contamination of the fabric surface was analyzed in terms of the pixels corresponding to the area of the fabric surface contaminated by silicate particles. Finished or unfinished nylon fabrics as well as cotton fabrics were contaminated with silicate particles, and their surfaces were scanned using the established camera. The proposed assessment method was found to be useful for quantitatively comparing the degree of particle contamination of the fabrics.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.3
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• pp.247-258
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• 2023

This study aims to investigate the enhancement of water resistance and improvement in adhesion to the skin by combining dextrin palmitate and isopropyl titanium triisostearate coating materials with titanium dioxide. Due to the recent increase in consumers who enjoy outdoor activities, the demand for sunscreen with excellent water resistance is increasing. Prior research was conducted with O/W, Pickering, and W/O/W multiple formulations, but there was a limit to water resistance. The purpose of this study is to develop a complex inorganic powder that can improve water resistance and increase adhesion to the skin to solve this problem. First, we combined dextrin palmitate and isopropyl titanium triisostearate coating materials to form a composite with titanium dioxide. The coating of the inorganic powder was confirmed using FE-SEM and FT-IR analysis. The composite exhibited significantly higher in vitro water resistance compared to other formulations. The hydrophobicity of the coated inorganic powder was compared by measuring the contact angles. When the coated inorganic powder was applied to the W/O sunscreen formulation and the non-coated inorganic powder was applied to the W/O sunscreen formulation as a control, the SPF of the sunscreen containing the coated inorganic powder was higher. These results were the same when observed with a UV camera. Finally the adhesion of the coated inorganic powder to the skin was assessed by applying it to a foundation product. In vivo study, it was observed that the product formulated with the coated powder exhibited less smudging compared to the foundation product formulated with the non-coated powder. The developed inorganic powder in this study demonstrated excellent adhesion to the skin, providing a superior sensory experience, as well as enhanced hydrophobicity and remarkable water resistance effects. In the future, the result of this study is expected to help develop various sunscreen products to improve water resistance.

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.450-455
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• 2016

Color change in single-crystal, yellow, red, purple, and colorless cubic zirconias (CZs) was investigated as a function of annealing in vacuum and air atmosphere at $800-1400^{\circ}C$ for 30 min, for development of a damascene process of plugging a precious metal paste at the elevated temperature. Coloring-element contents of the CZs were evaluated using WD-XRF, and the color change determined visually by naked eye, and using a digital camera and UV-Vis-NIR color analyzer. WD-XRF showed that all of the CZs had cubic-phase stabilizer elements and coloring elements. All CZs that underwent vacuum annealing exhibited a slight color change at $<900^{\circ}C$, while their colors began to change to black at $1100^{\circ}C$, and became opaque black at $1400^{\circ}C$. After air annealing, there was almost no color change up to $1400^{\circ}C$. Since red and purple CZs showed greater color difference (CD) values than the others, the degree of CD is likely to depend on the original color of the CZ due to the different stabilities of their coloring elements during annealing. Based on our results, it is suggested that annealing in air at $<900^{\circ}C$ is advantageous, and assorted colored CZs can be used for precious metal damascene.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.221-226
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• 2018

The property changes of 18, 14, and 8K green gold alloys for jewelry are observed by adding 0.0, 3.0, and 5.0 wt% of indium (In), respectively. To check the composition of the alloys, an energy dispersive spectroscopy (EDS) analysis is conducted. Color and microstructure analysis is executed through bare-eye, macro camera, UV-VIS-NIR-colormeter, and optical microscope. The melting point, wetting angle, and hardness are measured using TGA-DTA, a wetting angle tester, and a Vickers hardness tester. The EDS analysis result demonstrates that each of the green gold alloys was manufactured with purposed contents. The color analysis result shows that the color of the alloys is similar to the color of the conventional 4 wt%-Cd 18K green gold, and the green color improves as the In content increases. The micro structure analysis result demonstrates that grain refinement improves as the amount of In increases. Enhancements in the melting point, wettability, and Vickers hardness changes appear as the In content increases and Au content decreases. The hardness is up to 260, which implies good durability. Therefore, the results suggest that the proposed 18, 14, and 8K In-added green gold alloys enhance the properties of jewelry products with regard to the green color, castability, and durability.

• KSTLE International Journal
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• v.6 no.1
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• pp.28-32
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• 2005

The electrorheoloRical (ER) fluids are composed of a colloidal dispersion of polarizable particles in insulating oil, and it's the rheological property changes by the applied electric field. These changed are reversible and occur fast within a fewmilliseconds. The ER properties of the ER fluid such as increment of viscosity and yield stress come from the particle chain structure induced by electric fleld. When formulating the ER fluid for a speciflc application, some requirement must besatisfled, which are high yield stress under electric field, rapid response, and dispersion stability. While this characteristic makes valuable ER fluids in valious industrial applications, their lung term and quiescent application has been limited because ofproblems with particle sedimentation. In an effort to overcome sedimentation problem of ER fluids, the anhydrous ER materials of monodispersed hollow polyaniline (PANI) and adipate derivative respectively with submicron-sized suspension providing wide operating temperature range and other advantage were synthesized in a four-step procedure. The ER fluidswere characterized by FT-lR, TGA, DLS, SEM, and TEM. Stability of the suspensions was examined by an UV spectroscopy.The rheological and electrical properties of the suspension were investigated Couette-type rheometer with a high voltagegenerator, current density, and conductivity. And the behavior of ER suspensions was observed by a video camera attached toan optical microscope under 3kV/mm. The suspensions showed good ER properties, durability, and particle dispersion.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.45.3-46
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• 2018

Although mass accretion from the disk to the central protostar is a key process of low mass star formation, the accretion mechanism is still poorly understood. To investigate "episodic accretion", which has been suggested as an accretion mechanism in low mass star formation, we have carried out near-infrared spectroscopic observations of three very low-luminosity objects (VeLLOs) and one background source, using InfraRed Camera onboard the AKARI space telescope. The ice absorption features of $H_2O$, $CO_2$, and CO were detected around the wavelengths of 3.0, 4.26, and $4.67{\mu}m$, respectively. In addition, we revealed the XCN ice feature, which is attributed to high energy UV photons produced by the episodic burst accretion. The comparisons of the ice abundances of our targets with those of other YSOs observed previously with AKARI IRC imply that the three VeLLOs had experienced burst accretions although they are now in a very quiescent phase.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.443-445
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• 2015

We provide results of near-infrared (NIR) spectroscopic observations of 83 nearby (0.002< z <0.48) and bright (K <14 mag) type 1 active galactic nuclei (AGNs). For the observations, we used the Infrared Camera (IRC) on AKARI allowing us to obtain the spectrum in the rarely studied spectral range of $2.5-5.0{\mu}m$. The $2.5-5.0{\mu}m$ spectral region suffers less dust extinction than ultra violet (UV) or optical wavelength ranges, and contains several important emission lines such as $Br{\beta}$ ($2.63{\mu}m$), $Br{\alpha}$ ($4.05{\mu}m$), and polycyclic aromatic hydrocarbon (PAH; $3.3{\mu}m$). The sample is selected from the bright quasar surveys of Palomar Green and SNUQSO, and AGNs with black hole (BH) masses estimated from reverberation mapping method. We measure the Brackett line properties for 11 AGNs, which enable us to derive BH mass estimators and investigate circum-nuclear environments. Moreover, we perform spectral modeling to fit the hot and warm dust components by adding photometric data from SDSS, 2MASS, WISE, and ISO to the AKARI spectra, and estimate hot and warm dust temperatures of ~1100K and ~220 K, respectively.

• Journal of Industrial Technology
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• v.39 no.1
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• pp.33-39
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• 2019

This paper addresses effects of nanoscale structures on structural colors of micropatterned transparent substrate by light diffraction. Structural colors is widely investigated because they present colors without any chemical pigments. Typically structural colors is presented by diffraction of light on a micropatterned surface or by multiple interference of light on a surface containing a periodic or quasi-periodic nano-structures. In this paper, each structural colors induced by quasi-periodic nano-structures, periodic micro-structures, and nano/micro dual structures is measured in order to investigate effects of nanoscale and microscale structures on structural colors in the transparent substrate. Using pre-fabricated pattern mold and hot-embossing process, nanoscale and microscale structures are replicated on the transparent PMMA(Poly methyl methacrylate) substrate. Nanoscale and microscale pattern molds are prepared by anodic oxidation process of aluminum sheet and by reactive ion etching process of silicon wafer, respectively. Structural colors are captured by digital camera, and their optical transmittance spectrum are measured by UV/visible spectrometer. From experimental results, we found that nano-structures provide monotonic colors by multiple interference, and micro-structures induce iridescent colors by diffraction of light. Structural colors is permanent and unchangeable, thus it can be used in various application field such as security, color filter and so on.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.252-252
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• 2016

최근 학계나 산업계에서 indium tin oxide (ITO)의 높은 전기 전도도 및 광투과율을 이용하여 줄 발열을 기초로 하는 투명 면상 발열체에 대한 연구가 활발히 진행 되고 있다. 하지만 단일 ITO 박막으로 제작한 투명 면상 발열체는 온도가 상승함에 따라 균일하게 발열 되지 않으며, 글라스의 곡면 부분에서 유연성이 부족하여 크랙이 발생하는 다양한 문제점들을 가지고 있다. 이를 해결하기 위해 ITO의 결정화 온도 $160^{\circ}C$ 이상의 고온공정 또는 증착 후 열처리가 필요 하는 추가적인 공정이 필요하다. 따라서 본 연구에서는 단일 ITO 박막의 단점을 개선하는 ITO/Ag/ITO 하이브리드 구조의 투명 면상 발열체를 제작하여 전기적, 광학적 특성을 비교하고 발열량, 온도 균일성, 발열 유지 안정도를 조사하였다. 본 연구에서는 $50{\times}50mm$ 크기의 non-alkali glass (Corning E-2000) 기판 상에 마그네트론 스퍼터링 공정으로 상온에서 ITO/Ag/ITO 박막을 연속적으로 증착 하여 다층구조의 하이브리드 형 투명 면상 발열체를 제조하였다. 박막 증착 파워는 DC (Ag) power 100 W, RF (ITO) power 200 W로 하였으며 ITO박막두께는 40 nm로 고정 시키고 Ag박막 두께는 10 ~ 20 nm로 변화를 주었다. 증착원은 3인치 ITO 단일 타깃(SnO2, 10 wt.%)과 Ag 금속 타깃 (순도 99.99%)을 사용하였으며, 고순도 Ar을 이용하여 방전하였으며 총 주입량은 20 sccm, working pressure는 1.0 Pa을 유지하였다. 증착전 타깃 표면의 불순물 제거와 방전의 안정성을 유지하기 위해 10분간 pre-sputtering을 진행하고 증착하였다. 증착한 박막의 전기적, 광학적 특성은 각각 Hall-effect measurements system (ECOPIA, HMS3000), UV-Vis spectrophotometer (UV-1800, SHIMADZU)으로 측정하였으며, 하이브리드 표면의 구조 및 형상은 field emission-scanning electron microscopy (FE-SEM, Hitachi S-4800)으로 관찰하였다. 또한 투명 면상 발열체의 성능은 0.5 ~ 3 V/cm의 다양한 전압을 power supply (Keithly 2400, USA)를 통해서 시편 양 끝단에 인가한 후 시간에 따른 투명면상 발열체의 표면 온도변화를 infrared thermal imager (IR camera, Nikon)를 이용하여 관찰하였다. 하이브리드 구조를 가진 ITO박막의 두께는 40 nm로 고정 시키고 Ag박막의 두께는 10, 15, 20 nm로 변화를 주었다. 이들 박막의 면저항 값은 각각 5.3, 3.2, $2.1{\Omega}/{\Box}$였으며, 투과도는 각각 86.9, 81.7, 66.5 %였다. 이에 비해 두께 95 nm의 단일 ITO박막의 면저항 값은 $59.5{\Omega}/{\Box}$였으며, 투과도는 89.1 %였다. 하이브리드 구조의 전기적특성은 금속층의 두께가 증가할수록 캐리어 농도 값이 증가함에 따라 비저항 값이 감소되어 면저항 값도 감소된 것이며, 금속 삽입층의 전도특성이 비저항에 큰 영향을 주고 있음을 보여준다. 하지만 금속 층의 두께가 증가할수록 Ag층이 연속적인 막을 형성하여 반사율이 증가함에 따라 투과도가 감소하였다. 따라서 하이브리드 구조를 가진 투명 면상 발열체에 금속 삽입층의 두께 조절은 매우 중요한 인자임을 확인 할 수 있었다. 또한 발열성능을 평가 하기 위해 시편 양 끝단에 3 V전압을 인가한 결과, 금속 삽입층의 두께가 10 nm에서 5 nm씩 증가한 하이브리드 구조를 가진 투명면상 발열체의 최고 온도는 각각 98, 150, $167^{\circ}C$ 였으며, 단일 ITO의 최고 온도는 $32^{\circ}C$였다. 이 것은 동일한 두께 (95 nm)의 단일 ITO 박막과 비교하여 면저항이 낮은 하이브리드 박막의 발열량은 약 $120^{\circ}C$로 발열효율이 매우 우수한 것을 확인 할 수 있었다.