• 소성∙가공
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• 제32권6호
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• pp.360-366
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• 2023

This study is concerned with the surface quality of products according to the material and coating condition of the forming tool in incremental sheet forming. Three forming tools, SKD11 with and without diamond-like-coating (DLC) and polymer tool tip, were used to form conical and pyramidal geometries to take into account the influence of friction between the forming tool and the sheet on the surface quality including geometric accuracy of deformed samples. Each test was performed using SUS304 with a thickness of 0.4 mm according to different incremental depths per lap of 0.5 mm, 1.0 mm, and 1.5 mm for the contour tool path, considering the increase in normal force which is associated with the frictional behavior during local deformation. The surface quality was then investigated through surface roughness measured with KEYENCE VR-6000 and relative strain distribution including deformed shape analyzed with ARGUS which is a non-contact optical strain measurement system. Differences between 3D CAD surfaces and captured geometry from experiments were evaluated to compare the effect of friction on geometric accuracy. From comparisons of experimental results, it was revealed that the polymer-based tool tip can improve surface quality and geometric accuracy by reducing the undesired material flow due to local friction in the increment sheet forming process.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.33-38
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• 2002

An optical single cylinder diesel engine equipped with a common-rail injection system has been built to investigate diesel combustion and emission characteristics. Three optical widows (piston crown quartz for bottom view of the cylinder, upper piston quartz for allowing laser sheet and liner quartz for side view) have been placed in the optical engine to visualize spray characteristics and combustion process inside the cylinder. Before doing further research using various optical diagnostics with the optical engine, fundamental combustion experiments and flame visualization incorporating a high speed motion analyser have been carried out with a wide range of engine operating conditions.

• Current Optics and Photonics
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• 제6권1호
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• pp.15-22
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• 2022

This paper describes the construction of a phase shifter with low loss and small volume. To construct it, we use the two graphene layers that are separated by a hexagonal boron nitride (hBN) and embedded in a silicon waveguide. The refractive index of the waveguide is adjusted by applying a bias voltage to the graphene sheet to create an optical phase shift. This waveguide is a compact device that only has a radius of 5 ㎛. It has a phase shift of 6π. In addition, the extinction ratio (ER) is 11.6 dB and the insertion loss (IL) is 0.031 dB. Due to its unique characteristics, this device has great potential in silicon on-chip optical interconnection and all-optical multiple-input multiple-output processing.

• 분석과학
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• 제19권5호
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• pp.389-393
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• 2006

ZnS(Ag) 섬광체와 광전자증배관(PMT)으로 구성된 검출기는 원자력시설에서 알파선 측정용 장치로 많이 사용되고 있다. 이들 검출기는 대부분이 분말 상태의 ZnS(Ag) 섬광체를 투명한 플라스틱 소재 위에 얇게 발라서 제조한다. 본 연구에서는 간단한 방법을 이용하여 ZnS(Ag) 섬광 검출소재를 제조하기 위한 조건을 확립하였다. 검출소재는 지지체 고분자 필름과 ZnS(Ag) 섬광층로 구성된 이중구조로 제조하였으며, 지지체 필름은 고분자 소재를 녹인 후 casting 방법으로 제조하였고, ZnS(Ag) 섬광층은 접착제에 ZnS(Ag) 분말을 첨가하여 screen printing 기법으로 제조하였다. 이와 같은 제조공정을 이용하여 다양한 소재에 대한 평가 결과, 지지체 필름의 고분자 소재로서는 PSf이 가장 우수하였고, 접착제로서는 cyano resin이 가장 적합하다는 것을 확인하였다. 또한, 제조한 섬광 검출소재는 충분한 기계적 강도와 섬광체로서의 우수한 투명도를 가진다는 것을 확인하였으며, 알파선 검출 성능도 확인하였다.

• 한국진공학회지
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• 제20권5호
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• pp.356-360
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• 2011

유리 기판 위에 RF와 DC 마그네트론 스퍼터링 방법으로 100 nm 두께의 $In_2O_3$ 단층 박막과 $In_2O_3$ 100 nm/Cu 3 nm의 두께를 갖는 적층박막을 증착하고, 구리 기저 층 증착에 따른 상부 $In_2O_3$ 박막의 광학적, 전기적 특성의 변화를 연구하였다. 상온에서 증착 된 $In_2O_3$ 박막의 가시광 투과도와 면 저항은 79%와 2,300 ${\Omega}/{\square}$이었다. 구리 기저 층의 광 흡수에 의하여, $In_2O_3$/Cu 적층박막의 가시광 투과도는 71%로 감소하였으나, 면 저항은 110 ${\Omega}/{\square}$로 측정되어 상대적으로 우수한 전기적 특성을 구할 수 있었다. 본 연구에서 Figure of Merit 분석을 통하여 구리 기저 층이 상부 $In_2O_3$ 투명전극의 전기적, 광학적 특성을 개선 할 수 있음을 확인하였다.

• 반도체디스플레이기술학회지
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• 제10권4호
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• pp.43-46
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• 2011

In this study, we investigated the effects of the post Ar plasma treatment at different RF powers for various durations on electrical, structural, and optical properties of relatively thin Al-doped zinc oxide films. The sheet resistance was observed to decrease rapidly for the first 5min, beyond which the resistance apparently saturated. As the RF power increased, the grain size and the interplanar distance of (002) planes also increased. The observed decrease in sheet resistance was stated to be a consequence of Al and/or Zn interstitials as well as grain growth. It was also found that Ar plasma treatment increased the transmittance of Al-doped zinc oxide films in most of the visible light range below the blue light.

• 반도체디스플레이기술학회지
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• 제18권3호
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• pp.36-41
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• 2019

Hybrid-type transparent electrodes were fabricated by depositing carbon nanotubes (CNTs) via spray coating on polyethylene terephthalate (PET) substrates and then coating the CNTs with [poly(3,4-ethylenedioxythiophene)] (PEDOT) films via electro-polymerization. For all of the fabricated electrodes, their surface morphologies, electric sheet resistances, visible transmittances, and color properties (e.g., yellowness) were characterized as functions of the applied voltages and process times used in electro-polymerization. The sheet resistance of the CNTs was significantly reduced by the coating of PEDOT, while their visible transmittances slightly decreased. The yellowness values of the PEDOT-coated CNTs were observed to have substantially decreased via electro-polymerization. The experimental results confirmed that the fabricated hybrid electrodes had desirable properties for the application of transparent electrode in terms of the electrical resistance, optical transmittance, and chromaticity.

• 한국생산제조학회지
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• 제22권3호
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• pp.480-487
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• 2013

In this study, we researched the LED source MR16,which maintains the strong points of an ordinary MR16 while compensating for its weak points. The optical system composition of the LED MR16 includes four aspherical lens per sheet and a patterned reflector. The aspherical optical system and reflector were designed using optical software, and the performance was estimated using a lighting simulation program. Finally, a prototype was manufactured after analyzing the simulation data, and the reliability of the simulation results was estimated using a comparative analysis of the designed data and measured data.

• 열처리공학회지
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• 제25권2호
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• pp.85-89
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• 2012

Transparent conductive ZnO/Ag/ZnO (ZAZ) multilayer films were deposited by Radio frequency (RF) magnetron sputtering and direct current (DC) magnetron sputtering. The effects of post deposition vacuum annealing temperature on the structural, electrical and optical properties of the ZAZ multilayer films were investigated. The thickness of ZAZ films is kept constant at ZnO 50 nm/Ag 5nm/ZnO 45 nm, while the vacuum annealing temperatures were varied from 200 and $400^{\circ}C$, respectively. As-deposited ZAZ films exhibit a sheet resistance of $6.1{\Omega}/{\Box}$ and optical transmittance of 72.7%. By increasing annealing temperature to $200^{\circ}C$, the resistivity decreased to as low as $5.3{\Omega}/{\Box}$ and optical transmittance also increased to as high as 82.1%. Post-deposition annealing of ZAZ multilayer films lead to considerably lower electrical resistivity and higher optical transparency, simultaneously by increased crystallization of the films.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1436-1441
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• 2006

Each type of optical sheets in a LCD module experiences a characteristic behavior for thermal loading and unloading. During thermal cycling, a polymeric behavior is reversible and recyclable, depending on a material stiffness critically affected by temperature and time. Some critical issues on temperature- and time-dependent themomechanical deformation of the polymeric sheet are addressed by finite-element thermal results, followed by structural simulation results in this study.