• 대한원격탐사학회지
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• 제26권4호
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• pp.373-385
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• 2010

두 대의 레이더를 이용하여 반사도를 합성할 때 중복영역을 처리하는 새로운 합성 방법을 개발하였다. 이 합성 방법은 인접한 두 레이더의 중복되는 영역의 반사도 차이를 보정한 후 가중치를 주어 합성하는 방법이다. 가중치는 CAPPI(Constant Altitude PPI) 고도와 반사도가 관측된 고도와의 차이의 비를 역으로 계산한 것이다. 이 합성방법의 결과를 분석하기 위하여 두 레이더를 이용하여 관측한 태풍 사례의 반사도장에 대해 다른 합성방법(최댓값, 평균값, 근거리, 거리 가중)과 비교하였다. 두 레이더의 중복영역의 경계지점들에 대해 반사도의 연속성과 치우침을 분석하였고 그 결과 새로운 방법이 다른 합성방법에 비해 더 우수한 결과를 얻었다.

• 대기
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• 제15권3호
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• pp.155-165
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• 2005

The characteristics of six precipitation systems occurred around Cheongju in 2002 are analyzed after the convective/stratiform radar echo classification using radar reflectivity from the Meteorological Research Institute"s X-band Doppler weather radar. The Biggerstaff and Listemaa (2000) algorithm is applied for the classification and reveals a physical characteristics of the convective and stratiform rain diagnosed from the three-dimensional structure of the radar reflectivity. The area satisfying the vertical profile of radar reflectivity is well classified, while the area near the radar site and the topography-shielded area show a mis-classification. The seasonal characteristics of the precipitation system are also analyzed using the contoured frequency by altitude diagrams (CFADs). The heights of maximum reflectivity are 4 km and 5.5 km in spring and summer, respectively, and the vertical gradient of radar reflectivity from 1.5 km to the melting layer in spring is larger than in summer.

• 한국광학회지
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• 제10권6호
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• pp.524-526
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• 1999

본 논문에서는 외부 공진기 반도체 링 레이저 내부에 에탈론을 삽입함으로써 외부 공진기 링 레이저의 종모드 간격이 현저히 변화하는 사실을 관측하고 이에 대한 이론적 분석을 수행하였다. 외부공진기 링 레이저의 종 모드 간격은 에탈론의 단면 반사율에 의존하여 변화하였으며, 공진모드의 분석을 통해 이에 대한 정량적인 해석을 보였다. 또한 이러한 효과가 에탈론이나 FP 필터의 단면 반사율의 정밀한 측정에 응용될 수 있다는 것을 실험을 통해 증명하였다. 제안된 방법은 특히 높은 반사율에 대해서도 정밀한 측정결과를 얻을 수 있으며 측정이 쉽고 매우 빠르게 이루어진다.

• 펄프종이기술
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• 제38권3호
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• pp.7-12
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• 2006

The pore structure of paper was modified by the application of the blending of pulp, refining, and filler particle size and ash content. It was conformed that the reflectivity of paper can be modified by the combination of the above parameters. It was also found that the change of reflectivity of paper was greatly dependent on the pore structure, such as average pore size, pore size distribution and porosity. The average pore size was decreased with addition of HwBKP, but the smallest average pore size was obtained from the addition of 80% HwBKP Refining of pulp decreased both average pore size and the reflectivity of paper. The pore size distribution of filled paper can be varied by the combination of filler particle size and ash content

• 제어로봇시스템학회논문지
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• 제18권1호
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• pp.62-68
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• 2012

In this paper, a detection method of a pedestrian safety road marking was proposed. The proposed algorithm uses laser range and reflectivity of a range finder (LRF). For a detection of crosswalk marking and stop line, the DFT (Discrete Fourier Transform) of reflectivity and cross-correlation method between the reference replica and the measured reflectivity are used. A speed bump is detected through measuring an altitude difference of two LRFs which have the different tilted angle. Furthermore, we proposed a velocity constrained a detection method of a speed bump. Finally, the proposed methods are tested in on-line, on the pavement of a road. The considered road markings are wholly detected. The localization errors of both road markings are smaller than 0.4 meter.

• 대한금속재료학회지
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• 제50권8호
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• pp.563-568
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• 2012

The wetting property and reflectivity of Sn-3.5Ag solder which was dip coated on a LED lead frame were investigated. The wettability of molten solder on Cu substrate was evaluated by the wetting balance tester, and surface tension was calculated from maximum withdrawal force and withdrawal time. Temperature of the molten solder in a bath was varied in the range of $250-290^{\circ}C$. With increasing temperature, the surface tension decreased a little. The reflectivity of Sn-3.5Ag coated on a substrate became a little lower than the highest current LED lead frame reflectivity.

• 마이크로전자및패키징학회지
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• 제8권2호
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• pp.19-24
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• 2001

EUV 노광공정의 반사형 노광계 및 마스크에 사용되는 Mo/Si 다층박막 착탁 시 발생하는 각 층의 두께 변화와 상호확산 층 (inter-diffusion layer)이 생성될 경우에 대하여 이들이 다층박막 반사도에 미치는 영향을 전산모사를 통하여 알아보았다. 본 연구그룹에서 개발한 다층박막 반사 시뮬레이션 프로그램을 사용하여 Mo/Si 40-period박막의 반사토플 계산한 결과, 각각의 period가 두께의 편챠(28%)를 갖는 경우, 모든 period가 같은 두께를 갖는 다층박막에 비해 최대반사도가 10.8% 감소가 되었으며 두 층간 물질 사이의 상호확산(interdiffustion) 층을 가정하였을 경우, 다층박막의 경우 그렇지 않은 경우에 비해 4.7%의 최대반사도가 감소가 예상되었다. 그리고 각 층의 적층에 따른 반사도의 변화를 시뮬레이션 프로그램을 통해 계산한 결과 반사도는 25층까지 계속 증가하며 26층부터 불규칙한 경향성을 가지며 증가와 감소를 반복함을 알 수 있었다.

• 한국세라믹학회지
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• 제36권9호
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• pp.915-922
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• 1999

Microwave dielectric properties and far infrared reflectivity spectra of the (Zr0.8Sn0.2)TiO4 ceramics were inves-tigated with the various cooling rate. Dielectric constant was nearly same value while the unloaded Q value was largely affected by cooling rate. The Q.f of 42,140 at 7 GHz was obtained for the specimens with cooling rate of 1$^{\circ}C$/min. The effect of the cooling rate on the change of the ionic the electronic polarization and the intrinsic microwave loss of the specimens were investigated by the infrared reflectivity spectra from 50 to 4000cm-1 which were calculated by Kramers-Kroning analysis and the classical oscillator model. The relative tendency of microwave dielectric properties of the specimens calculated from the relfectivity data were in good agreement with the results by the post resonant method.

• Transactions on Electrical and Electronic Materials
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• 제15권3호
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• pp.159-163
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• 2014

More accurate CD (Critical Dimension) control is required for the nanometer-scaled devices. However, since the reflectivity between substrate and PR (Photoresist) becomes higher, the CD (Critical Dimension) swing curve was intensified. The higher reflectivity also causes PR notching due to the pattern of sub-layer. For this device requirement, it was optimized for the thickness, refractive index(n) and absorption coefficient(k) in the bottom anti-reflective coating(BARC; SiON) and photoresist with the minimum reflectivity. The computational simulated conditions, which were determined with the thickness of 33 nm, n of 1.89 and k of 0.369 as the optimum condition, were successfully applied to the experiments with no standing wave for the 0.13um-device. At this condition, the lowest reflectivity was 0.44%. This optimum condition for BARC SiON film was applied to the process for 0.13um-device. The optimum SiON film as BARC to PR and sub-layer could be formed with the accurate CD control and no standing waver for the nanometer-scaled semiconductor manufacturing process.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.507-516
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• 2014

We present a hybrid method for spectral reflectivity recovery, using 3D extrapolation as a supplemental method for 3D interpolation. The proposed 3D extrapolation is an extended version of 3D interpolation based on the barycentric algorithm. It is faster and more accurate than the conventional spectral-recovery techniques of principal-component analysis and nonnegative matrix transformation. Four different extrapolation techniques (based on nearest neighbors, circumcenters, in-centers, and centroids) are formulated and applied to recover spectral reflectivity. Under the standard conditions of a D65 illuminant and 1964 $10^{\circ}$ observer, all reflectivity data from 1269 Munsell color chips are successfully reconstructed. The superiority of the proposed method is demonstrated using statistical data to compare coefficients of correlation and determination. The proposed hybrid method can be applied for fast and accurate spectral reflectivity recovery in image processing.