• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.421-428
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• 2008

For last decades, the rapid coastal erosion process spreading along Korean peninsular has become a nuisance especially for tourism and local economy. Global warming and sea-level rise demand persistently new coastal protection strategies against the conventional methods using armored structures. In a view of this, Kweon et al. (2007) has proposed a new type of horizontal steel plates for an ideal candidate as eco-friendly detached breakwater systems for global warming era. The breakwater is composed of piles and horizontal porous plates that was devised for the optimized blockage effects and wave energy dissipations. This system provides outstanding performances as wave barrier and added advantages such as a rapid installation, an easy relocation, a perfect water circulation for the stagnation of pollutions in sheltered regions. The present experimental study focuses on the performance evaluations of the proposed system in wind wave conditions as a wave dissipator and reflector. The reflection, transmission, and energy dissipation of the random waves has been discussed in detail based on a newly proposed relation between wave steepness and a plate width normalized by wave length that are major factors affecting the wave transmission.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.451-451
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• 2010

최근들어 80인치 이상의 대경 고화질 display 및 휴대용 projection display 제작이 가능한 LCoS (Liquid Crystal on Silicon) display에 대한 관심이 높아지고 있다. LCoS projection display는 높은 개구율, 빠른 응답속도, 고화질, 대형 디스플레이 임에도 불구하고 낮은 제조단가 등의 여러 가지 장점을 가지고 있다. LCoS projection display의 핵심 기술로는 높은 투과도와 낮은 반사율을 갖는 유리기판, 무기 배향막 증착 기술, Si back plane과의 접합기술 등이 있다. 이 중 LCoS projection display 제작을 위한 첫 단계인 유리기판은 가시광선 영역에서 96% 이상의 높은 투과도와 3% 미만의 반사도를 요구하는 기술을 필요로 한다. 본 연구에서는 indium이 doping된 tin oxide (ITO)를 투명 전도성막으로 사용하고, $SiO_2/MgF_2$ 이중 박막을 반사방지막으로 채택하여 고투과도 및 저반사율을 갖는 유리기판 제조에 응용하였다. 먼저 15nm 두께의 ITO 박막을 DC sputtering을 이용하여 8-inch 크기의 corning1737 유리기판 상에 증착한 후, 그 반대편에 e-beam evaporation 장비를 사용하여 120nm 두께의 반사 방지막을 증착하였다. 또한 유리기판 상에 증착된 투명 전도성막의 표면개질을 위하여 Ar plasma를 이용하여 treatment를 수행하였다. 이 때 sputtering 조건은 DC power, Ar 유량 및 압력을 조절함으로서 높은 투과도를 갖는 최적의 조건을 구현하였고, e-beam evaporation을 이용한 반사방지막 증착 조건은 $SiO_2$와 $MgF_2$의 계면에서 빛의 반사를 최소화할 수 있는 최적의 조건을 구현하였다. 제작된 유리기판은 가시광선 영역에서 97% 이상의 투과도를 보였으며, 최대 2.8%의 반사율을 보여, LCoS display 제작에 적합함을 확인할 수 있었다. 또한 Ar plasma 처리 후 ITO 박막의 면저항 값은 $100\;{\omega}/{\Box}$, 표면 거칠기는 rms 값 기준 0.095nm, 접촉각 $20.8^{\circ}$의 특성을 보여, 타 index matched transparent conducting oxide가 coating된 유리기판에 비해 우수한 특성을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.4
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• pp.193-200
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• 1985

In the reflection and transmission of a plane wave(TE) from a dielectric plane surface oscillating sinusoidally perpendicular to its surface, one could assume that the boundary moves with a uniform velocity equal to the instantaneous oscillating velocity. The reflected and the transmitted fields are obtained as the function of the incident angles, the dielecri'c permittivity, and the oscillating velocities according to the extended Lorentz transform.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.6
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• pp.586-595
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• 2007

The analytic solution of wave scattering of monochromatic waves on a pile breakwater by an eigenfunction expansion method is extended to the case of directional irregular waves. The scattering wave spectrum and the force spectrum can be expressed from the reflection coefficient, transmission coefficient and the wave forces obtained from changing frequencies and incident angles in monochromatic waves. By numerical integration of 2-dimensional spectrum which is function of frequencies and incident angles, the representative values for the scattered waves and wave forces are obtained and the dependence of the transmission coefficients and wave forces on the directional distribution function, the principal wave direction, the submergence depth, and porosity is analyzed.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.192-193
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• 2003

광학박막은 유리, 플라스틱, 실리콘, 금속 기판 등에서 표면의 반사율, 투과율, 흡수율과 편광상태 등의 광학적 특성을 변화시키기 위해 광학표면에 코팅을 하여 많이 사용하고 있으며, 파장영역으로는 수 nm의 연x선부터 자외선, 가시광선과 수십 $\mu$m의 적외선까지 적용할 수 있고, 광학기기에서는 대부분의 광학부품이 광학적 특성을 증진시키기 위하여 각각의 목적에 맞도록 코팅되어 있다. 광학코팅의 종류로는 단순한 무반사코팅으로부터 고반사코팅, 칼라필터, 간섭필터, 편광분리기코팅, 마이너스필터 등까지 매우 다양하다. (중략)

• Korean Journal of Optics and Photonics
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• v.29 no.6
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• pp.262-267
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• 2018

In this paper, we designed a new antireflective film to improve the optical efficiency of organic light-emitting diode displays (OLEDs). The reflection characteristics in the normal and side viewing directions of OLEDs with the antireflective film were calculated, depending on the degree of polarization and transmittance of the currently used polarizer when used in the antireflective film of an OLED. The results showed that when the polarization degree of the commercial polarizer (99.990~99.995%) is lowered to 99.900%, the average reflectance of the antireflective film is increased by about 0.1% (2.5% in terms of rate of increase) which is difficult to notice with the human eye, while the transmittance is increased by 1.63~3.34% (4.2~8.2% in terms of rate of increase). This study provides an optimal design for high-light-efficiency OLEDs with good antireflection properties.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.222-223
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• 2000

지금까지 gold-coated 반사체, cusp-shaped 반사체, 복합 포물 반사체(CPC), 난반사 공동체 등 다양한 형태의 반사체가 횡펌핑을 이용한 Nd:YAG 레이저의 개발을 위하여 고안되어졌다. 횡여기되는 Nd:YAG 레이저의 광학적 효율은 반사체의 형태, 다이오드 레이저의 파장, Nd:YAG 결정의 지름, Nd$^3$의 도핑농도에 따라 영향을 받는다.$^{(1)}$ 본 연구에서는 고출력의 횡여기 Nd:YAG 레이저를 개발할 목적으로 광여기 공동으로 사용된 난반사 공동체의 내부지름과 레이저 매질인 Nd:YAG 결정의 흡수계수 등 매개변수를 변화시켜 흡수분포와 출력을 계산하였으며, 이러한 매개변수들이 기울기 효율에 미치는 영향을 수치 해석적으로 연구해 보았다. 광선추적법에서 사용한 매개변수 중에서 다이오드 레이저의 파장은 808 nm이고, 반사율은 90%이며, 여기 다이오드 출력은 1080 W이다. 난반사 공동체$^{(2)}$ 의 반사율은 95.7%이고, 결정의 투과율은 90%이며, 결정의 반지름은 2.5 mm이다. 사용된 여기 구조도는 그림 1과 같다. 여기헤드는 Nd:YAG 결정, 난반사 공동체, 그리고 3개의 360 W급 다이오드 어레이들로 구성되어 있다. (중략)

• Journal of the Microelectronics and Packaging Society
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• v.23 no.2
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• pp.91-96
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• 2016

In this study, effects of demolding temperature (DT) on the formability and optical properties were evaluated in order to optimize thermal nanoimprint lithography for anti-reflective film. Characterization on optical property showed that optical performance was gradually enhanced as the DT increased up to $70^{\circ}C$ while the transmittance and the reflectance was degraded as the DT increased further to $100^{\circ}C$. In addition, similar behavior was observed from formability analysis. It was contributed to the formation of free volume and viscose flow. Therefore, it was concluded that the formability and optical property are highly influenced by the formation of free volume and viscous flow of polymer depending on the DT.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.84-96
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• 2006

This paper presents a simplified numerical method that can be used to incorporate the partial reflection and transmission of water waves in the hyperbolic mild-slope equation. For given reflection and transmission coefficients, wave fields around a porous breakwater including reflection, transmission, and diffraction can be simulated accurately. For the verification of the proposed method, numerical experiments have been carried out and compared with analytic solutions given by Yu(1995) and McIver(1999). The proposed method is easy to implement and is computationally efficient. It is demonstrated that the method performs well with a sloping bottom bathymetry and varying incident wave angles.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.78-84
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• 1998

Refractive index was matched using the inhomogeneous dielectric layers to enhance the optical transmittance of surface discharge type AC PDP. The transmittance of upper panel which had two index-matched inhomogeneous dielectric layers was measured as 85%, and this result is regarded as 15% better transmittance than that of conventional structure, which is about 70%.