• 한국전기전자재료학회논문지
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• 제22권3호
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• pp.193-198
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• 2009

Recently, characteristic research by the changes in the spectrum, one of the factors that influence analysis of maximum output power of PV module, has been studied. In this paper, a one-day intensity of solar irradiation, change of spectrums with time and electrical output for spectrums are analyzed. As a result, blue-rich wavelength compared with red-rich wavelength has large variation of solar irradiance with time, so we recognized that change of solar irradiance is dominated by variation of blue~rich wavelength. Also in same intensity of solar irradiance, electrical output in blue-rich wavelength was 3-8 % higher than one in red-rich wavelength.

• 천문학회보
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• 제37권2호
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• pp.223.2-223.2
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• 2012

Grating spectrograph observation in near-infrared bands requires wavelength calibrations. We first need to extract order-strips from the echellogram data using flat images, and then to correct the spatial distortions and wavelength scales of the order strips using calibration arc lamps or the telluric OH emission lines. For very high resolution spectrograph using echelle, however, the arc lamps do not have enough emission lines in the order-strips, so we usually use the OH lines for accurate wavelength calibrations in wavelengths shorter than 2.3 microns. In this poster, we present wavelength calibration methods for longer wavelength bands using the telluric absorption lines in early-type stellar spectra and the telluric atmospheric transmission models. This technique will be applied to the data reduction pipeline for the IGRINS.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.326-336
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• 2008

A WDM-PON has been considered as an ultimate solution for access networks. However, there were many technical and practical issues for commercial deployment. These issues were solved with wavelength locked F-P LD and the WDM-PONs employing this optical source were commercialized. These WDM-PON systems have been deployed in Korea, Europe, and US. We reviewed wavelength locking technology and WDM-PON achievements. When we inject spectrum sliced broadband light into an F-P LD, the multimode output is changed to a quasi single mode. Then, we can use the single mode light for WDM signal transmission. The broad spectral gain of the semiconductor gain medium enables a color-free operation of WDM-PON, i.e., an identical ONT can be used for each user. The wavelength locking properties depend on many parameters, especially alignment of injection wavelength to a lasing mode, passband profile of AWG and front facet reflectivity of F-P LD. However, these dependencies can be reduced by proper design of the laser and the injection bandwidth. Thus, WDM-PON systems have been achieved with color-free operation.

• 한국컴퓨터정보학회논문지
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• 제10권6호
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• pp.209-218
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• 2005

링형 광 액세스망에서 능동형 광네트워크(AON: Active Optical Network)는 DWDM(Dense Wavelength Division Multiplexing)을 이용하여 요구대역폭(BoD: Bandwidth on Demand)에 따라서 가입자에게 원활한 서비스를 제공할 수 있다. 이를 위하여 기존의 광 기가비트 이더넷 스위치에서 다수개의 파장 및 서브캐리어(Sub-Carrier) 접속을 지원하며, 특정 파장을 분기하는 WADM (Wavelength Add Drop Multiplexer)과 링의 형태로 연결된다. WADM에서 분기된 특정 파장은 가입자단에 이르러 서브캐리어별로 역다중화 되어 가입자에게 분배되므로 가입자망의 분배가 시작되는 광 기가비트 이더넷 스위치와 가입자 단말 접속 장치간의 능동적인 연결이 가능한 구조를 가진다 본 논문에서는 이러한 AON 구조에서 BoD에 따라서 달라지는 버퍼의 크기를 비교 분석하고 또한 비트의 지체시간을 서버의 처리율과 비교 분석한다. 이러한 실험을 통하여 소요 시간의 한계를 결정함으로써 가입자에게 요구 대역폭에 따른 원활한 서비스를 제공할 수 있는 네트워크의 동적 운용 프로토콜 및 효율적인 알고리즘 구현을 위한 기준을 제시한다.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.109-118
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• 2015

Open raceway ponds are cost-efficient for mass cultivation of microalgae compared with photobioreactors. Although low-cost options like wastewater as nutrient source is studied to overcome the commercialization threshold for biodiesel production from microalgae, a cost analysis on the use of wastewater and other incremental increases in productivity has not been elucidated. We determined the effect of using wastewater and wavelength filters on microalgal productivity. Experimental results were then fitted into a model, and cost analysis was performed in comparison with control raceways. Three different microalgal strains, Chlorella vulgaris AG10032, Chlorella sp. JK2, and Scenedesmus sp. JK10, were tested for nutrient removal under different light wavelengths (blue, green, red, and white) using filters in batch cultivation. Blue wavelength showed an average of 27% higher nutrient removal and at least 42% higher chemical oxygen demand removal compared with white light. Naturally, the specific growth rate of microalgae cultivated under blue wavelength was on average 10.8% higher than white wavelength. Similarly, lipid productivity was highest in blue wavelength, at least 46.8% higher than white wavelength, whereas FAME composition revealed a mild increase in oleic and palmitic acid levels. Cost analysis reveals that raceways treating wastewater and using monochromatic wavelength would decrease costs from 2.71 to 0.73 $/kg biomass. We prove that increasing both biomass and lipid productivity is possible through cost-effective approaches, thereby accelerating the commercialization of low-value products from microalgae, like biodiesel.

• 한국광학회지
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• 제21권3호
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• pp.91-96
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• 2010

디지털 홀로그램을 이용하여 상을 재생 할 때 재생상의 크기는 재생거리와 파장의 함수이다. 이러한 재생거리와 파장 의존성을 제거하기 위하여 이중푸리에변환법이 제안되었고, 이중푸리에변환을 이용하면 일정 크기의 재생상을 얻을 수 있다. 일반적으로 사용된 광원의 파장보다 큰 단차의 높낮이 측정은 단일파장 디지털 홀로그래픽 방식으로 측정이 가능하지 않기 때문에 2 파장홀로그래피가 제안되었는데, 두 파장에서 얻어진 각각의 재생상의 크기가 같아야 하는 제약이 있다. 본 연구에서는 투과 및 반사형 2 파장 디지털 홀로그래픽 현미경을 이용하여 각각의 파장별로 홀로그램을 촬영하고 이중푸리에변환을 이용하여 재생함으로써 두개의 파장에서 얻어진 재생상의 크기를 같게 만들어 주는 과정 없이 단차를 가진 샘플의 3차원 높낮이 측정을 할 수 있었다.

• 대한전자공학회논문지SD
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• 제42권1호
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• pp.33-38
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• 2005

파장 고정된 Fabry-Perot 레이저를 사용하여 경제적인 고밀도 WDM-PON의 구현 가능성을 검증하였다. 중앙기지국에서 주입된 비간섭성광에 파장 고정된 Fabry-Perot 레이저를 이용하여 50 GHz 채널 간격의 파장분할 다중화된 4×622 Mb/s 상향신호를 30 km의 광섬유를 통해 성공적으로 전송하였다. 파장 고정된 Fabry-Perot 레이저 출력의 비팅 잡음 특성을 분석하여 Fabry-Perot 레이저가 주입되는 비간섭성 광의 강도 잡음을 억제함을 보였고, 이로 인해 50 GHz 채널 간격의 고밀도 WDM 전송이 가능함을 보였다.

• Journal of Photoscience
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• 제10권1호
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• pp.97-104
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• 2003

The excitation wavelength dependence of laser ablation dynamics of an azobenzene-containing urethane-urea copolymer film was investigated by measuring the laser fluence dependence of etch depth, transient absorbance change at each excitation wavelength, and transient absorption spectra. Moreover expansion/contraction dynamics was studied by applying nanosecond time-resolved interferometry. The threshold was determined at several excitation wavelengths from etch depth measurement, while time-integrated absorbance was obtained under excitation conditions. The photon energy required to remove the topmost of surface layer of the film did not .depend on excitation wavelength, and the penetration depth of excitation pulse dominated the etch depth. When the excitation wavelength was longer than 500 nm, permanent swelling was clearly observed but not for shorter wavelength excitation. In the latter case, photoisomerization occurred during excitation and the following photoreduction may play an important role. On the basis of the observations made in this study, a photochemical and photothermal mechanisms can explain mostly the short and long wavelength excitation results, respectively.

• 한국가시화정보학회지
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• 제12권3호
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• pp.9-14
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• 2014

Two-photon microscopy (TPM) has been used in plant research as a high-resolution high-depth 3D imaging modality. However, TPM is known to induce photo-damage to the plant in case of long time exposure, and optimal excitation wavelength for plant imaging has not been investigated. Longer excitation wavelength may be appropriate for in vivo two-photon imaging of Arabidopsis thaliana leaves, and effects of longer excitation wavelength were investigated in terms of imaging depth, emission spectrum. Changes of emission spectrum as a function of exposure time at longer excitation wavelength were measured for in vivo longitudinal imaging. Imaging depth was not changed much probably because photon scattering at the cell wall was a limiting factor. Chloroplast emission spectrum showed its intensity peak shift by 20 nm with transition of excitation wavelength from 849 nm or below to 850 nm or higher. Emission spectrum showed different change patterns with excitation wavelengths in longitudinal imaging. Longer excitation wavelengths appeared to interact with chloroplasts differently in comparison with 780 nm excitation wavelength, and may be good for in vivo imaging.

• Restorative Dentistry and Endodontics
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• 제26권2호
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• pp.127-133
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• 2001

There are several factors affecting the effectiveness of polymerization of the esthetic restorative materials. Among those factors, the initiator. camphoroquinone has the unique characteristic. of which the light sensitivity is very dependent on the wavelength of blue light. Camphoroquinone shows the most light absorption ability in the wavelength range of 470nm. So most of clinically used light curing systems adopt this phenomenon as their polymerization mechanism. The most popular way of light curing system is standard 40 second curing. But the problem of standard curing technique shows the rapid increase of resin viscosity followed by the acceleration of polymerization and the limited resin flow, resulted in reduction of the physicalproperty of restoration by retained stress. The object of this study was to verify the effects of narrow-banded wavelength on the microhardness of the esthetic restorative materials. a composite resin and a compomer, using filters which have peak wave length of 430nm, 450nm, 470nm, respectively. The results were as follows: 1. All the experimental groups showed lower hardness value than the control group. 2. In DyractAP, the hardness value by wavelength showed the same changing pattern on both upper and lower surfaces. 3. In DenFil, the hardness value by wavelength showed different changing pattern on upper and lower surfaces. 4. The hardness ratio showed similar pattern to the hardness variation of lower surface. but there was no significant difference between measurement in 10 minutes and 3 days later, besides the increase of hardness value.