• Transactions on Electrical and Electronic Materials
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• 제8권6호
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• pp.268-273
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• 2007

In this study, It was studied about the luminance characteristics of 17 inch direct-type back light using EEFL(external electrode fluorescent lamp) and CCFL(cold cathode fluorescent lamp). The EEFL has a long life time because the electrode is installed outside of lamp. And it is produced in lower price than conventional CCFL. Moreover, it does not need process of installing internal electrode. However, the EEFL technology has several problems such as difficulty of designing driving inverter and preventing this phenomenon along the skin of lamps. We suggested two types of backlight unit for LCD TV application using the EEFL and the CCFL. We found optimized optical design parameters. We set the optical variation parameters such as lamp height, lamp distance, total thickness, and angles of inner walls. We achieved 7580 nits of center luminance, 82% of luminance uniformity by using 20 lamps of the EEFL and 7297 nits of center luminance, 78% of luminance uniformity by using 16 lamps of the CCFL.

• 한국광학회지
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• 제23권5호
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• pp.222-226
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• 2012

본 논문에서는, LED 조명의 배광 특성의 조절이 용이한 반사컵 설계 방법을 제안하였다. 먼저 개별 반사컵의 구조와 높이에 대한 방사각의 변화 경향성을 파악하여, 높이에 따른 반사 특성을 확인하였다. 그 결과, 높이에 따라 반사 각도를 조절하여 설계함으로써 배광 분포의 세밀한 조절이 가능했다. 가장 간단한 2단 분할 방식의 경우 방사각의 제어나 균일도 개선을 할 수 있었다.

• 한국정보통신학회논문지
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• 제20권3호
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• pp.639-646
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• 2016

본 연구에서는 특수한 상황(미끄러짐 발생 및 회전관성이 부하로 작용하는 경우)에서의 회전 엔코더 기반 측정방법의 단점을 극복하기 위하여 광 변위센서(ADNS-9500)를 사용한 비접촉식 변위 측정방법을 제안하였다. 정확한 변위 측정을 위해 데이터 수집 보드와 랩뷰를 활용하여 실험적으로 광 변위센서의 성능을 분석하였으며, 반복실험을 통해 실험조건(측정방향, 속도, 가속도, 높이, 표면 재질)에 따른 광 변위센서의 성능특성을 파악하였다. 성능실험 결과, 광 변위센서를 사용하여 정확하게 평면운동을 측정하기 위해서는 광 변위센서와 지면(대상 물체의 표면)과의 높이를 2.4 mm-3.2 mm로 일정하게 유지시켜야 하며, 각각의 축 방향, 속도, 표면 재질을 고려하여 민감도를 수정하여 변위 계산식에 적용해야 하는 것을 확인하였다.

• 한국안전학회지
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• 제35권3호
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• pp.105-115
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• 2020

This study compares the difference of fit factors (FF) and visual acuity according to masks and eyeglasses preferences for 54 participants. We the precautions and behaviors of discomfort when wearing masks of eyewear wearers. Contact lens discomfort and priority action of complaints was investigated Glasses fitting factors is Optical Center Height(OH), Vertex Distance(VD) and Pantoscopic Angle(PA). We measured those factors and expressed by the ratio of standard point and change point. Quantitative fit factor was measured by Portacount Pro+ 8038. Also, we selected to 6 exercises among 8 exercises OSHA QNFT (Quantitative Fit testing) protocol to measure the fit factors. The pass/ fail criterion of FF was set at 100. Visual acuity(VA) test chart is developed by Chunsuk Han was used, Descriptive statistics was performed. Descriptive statistics(SAS ver 9.2), it is used geometric means, Wilcoxon analysis(P=0.05) When wearing the mask preferentially, fit factor(FF) was high according to the step of glasses fitting parameter. on the other hand, when the glasses first choice, the visual acuity(VA) was high. there was no significant difference. In the case of fit factor (FF), mask first choice/ glasses first choice is OH (p=0.671/ p=0.332), VD (p=0.602/ p=0.571) and PA (p=0.549/ p=0.607). Visual acuity (VA), mask first choice/ glasses first choice is OH (p=0.753/ p=0.386), VD (p=0.815/ p=0.557) and PA (p=0.856/ p=0.562). The workers of workplace and office chose glasses but occupational health workers and students chose mask. In case of discomforts, it was suggested to remove the mask and tolerate discomforts. The main discomforts and usual action of lens were dryness, hyperemia, foreign body sensation, ophthalmodynia, decreased vision and glasses wearing. Therefore, it is necessary to develop a mask wearing method education program considering glasses fitting and develop a hybrid model that minimizes inconvenience when wearing glasses and a mask at the same time.

• Ocean Science Journal
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• 제42권1호
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• pp.49-59
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• 2007

Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyll-a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

• 한국안광학회지
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• 제15권4호
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• pp.355-360
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• 2010

목적: 국내에서 시판되는 안경렌즈의 성능을 분석하고 최적화 설계로 수차가 보정된 안경렌즈를 설계하였다. 방법: 굴절률 1.6의 재질을 갖는 4개 회사의 ${\pm}$5.00D의 구면 렌즈와 비구면 렌즈의 중심두께, 곡률반경, 비구면 계수를 측정하였다. Mitutoyo사의 ID-F150으로 중심두께를 측정하였고, Automation Robotics사의 FOCOVISION(SR-2)를 이용하여 곡률반경을 측정하였다. 비구면 계수는 Taylor Hobson사의 PGI 1240S로 측정하였다. 렌즈 후면부터 눈의 회선점까지의 거리 27 mm, 동공직경 4 mm, 중심시야 $30^{\circ}$에서 적은 양의 수차를 갖는 안경렌즈를 설계하였다. 측정 렌즈보다 Axial height를 짧게 함으로써 미용 상의 이점을 높였다. 설계에는 ORA사의 Code V를 이용했다. 결과: -5.00D 비구면 렌즈는 구면 렌즈보다 비점수차와 왜곡수차는 약간 크게 나타났으나 Axial height가 짧고 가장자리 두께가 감소하여 미용 상의 장점이 있다. +5.00D 비구면 렌즈는 왜곡수차의 성능이 향상되고 (-)렌즈와 마찬가지로 Axial height와 중심두께의 감소로 미용 상의 장점을 확인하였다. 최적화 과정을 통한 전면 비구면 렌즈는 비점수차와 왜곡수차가 측정 구면 렌즈보다 좋은 성능과 미용 상의 장점을 확인할 수 있다. 결론: 국내에서 시판되는 비구면 렌즈는 수차의 성능보다는 미용 상의 장점을 키우는 Axial height의 감소와 두께의 감소에 주안점을 둔전면 비구면 설계가 이뤄지고 있다. 최적화 설계이론을 통해 측정렌즈보다 향상된 수차성능과 미용 상의 이점을 모두 갖는 전면 비구면 안경렌즈의 설계를 하였다. 후면 비구면 렌즈의 설계를 통해 전면 비구면 렌즈보다 향상된 성능을 얻을 수 있음을 기대할 수 있다.

• 한국광학회지
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• 제20권2호
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• pp.81-86
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• 2009

디지털 홀로그램과 굴절률 차이를 이용하여 사용된 광원의 파장보다 큰 단차를 측정하는 연구를 하였다. 위상차를 측정하여 단차를 측정하는 방식에서는 위상차가 $2{\pi}$보다 큰 경우에는 원리상 단차를 구하기 어렵다. 이를 보완하기 위하여 굴절률 차이를 이용하여 인위적으로 광경로차를 줄여 파장보다 큰 단차를 측정할 수 있는 디지털 홀로그래피 시스템을 구성하였고, 실험적으로 파장의 약 3배 이상의 단차를 측정하였다.

• 한국대기환경학회지
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• 제23권1호
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• pp.97-109
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• 2007

Vertical distribution and optical properties of atmospheric aerosols above the Korean peninsula are quite important to estimate effects of aerosol on atmospheric environment and regional radiative forcing. For the first time in Korea, vertical microphysical properties of atmospheric aerosol obtained by inversion algorithm were analyzed based on optical data of multi-wavelength Raman lidar system developed by the Advanced Environmental Monitoring Research Center (ADEMRC), Gwangju Institute Science and Technology (GIST). Data collected on 14 June 2004 at Gwangju ($35.10^{\circ}N,\;126.53^{\circ}E$) and 27 May 2005 at Anmyeon island ($36.32^{\circ}N,\;126.19^{\circ}E$) were used as raw optical data for inversion algorithm. Siberian forest fire smoke and local originated haze were observed above and within the height of PBL, respectively on 14 June 2004 according to NOAA/Hysplit backstrajectory analysis. The inversion of lidar optical data resulted in particle effective radii around $0.31{\sim}0.33{\mu}m$, single scattering albedo between $0.964{\sim}0.977$ at 532 nm in PBL and effective radii of $0.27{\mu}m$ and single scattering albedo between $0.923{\sim}0.924$ above PBL. In the case on 27 May 2005, biomass burning from east China was a main source of aerosol plume. The inversion results of the data on 27 May 2005 were found to be particle effective radii between $0.23{\sim}0.24{\mu}m$, single scattering albedo around $0.924{\sim}0.929$ at 532 nm. Additionally, the inversion values were well matched with those of Sun/sky radiometer in measurement period.

• 한국전기전자재료학회논문지
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• 제24권10호
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• pp.817-821
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• 2011

We have proposed an optical thin film and micro lens to improve the luminance of organic light emitting device. The first method, optical thin film was calculated refractive index of dielectric layer material that was modulated refractive index of organic material, ITO (indium tin oxide)and glass. The second method, microlens was applied with lenses on the organic device. Optical thin films were designed with Macleod Simulator and Micro Lenses were calculated by FDTD (finite-difference time-domain) solution. The structure of thin film was designed in organic material/ITO/dielectric layer/glass. The lenses size, height and distance were 5 ${\mu}m$, 1 ${\mu}m$, 1 ${\mu}m$, respectively. The material of micro lenses used silicon dioxide. Result, The highest luminance of OLED which applied with microlens was 11,185 $cd/m^2$, when approval voltage was 14.5 V, applied thin film was 5,857 $cd/m^2$. The device efficiency applying microlens increased 3 times than the device which does not apply microlens.

• 조명전기설비학회논문지
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• 제30권3호
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• pp.21-29
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• 2016

In this paper, optical tracking and analysis was carried out to find the optical properties with respect to various geometric design parameters of collimator lens which is very efficient when collect the light. As a result, a whole, ellipse incident part can obtain a high light efficiency and a narrow beam angle, and angled cylinder incident part is confirmed to obtain high efficiency and a narrow beam angle at a certain height or more. When Transmission part have a specific surface which can reflect the light in forward direction, a good optical properties was confirmed.