• 한국산림과학회지
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• 제87권3호
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• pp.493-500
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• 1998

본 연구는 광도가 층층나무 자엽단계 유묘의 생장에 미치는 영향과 생장에 필요로 하는 한계광도를 구명하기 위하여 자엽단계의 유묘를 대상으로 385, 32, 17, 8 및 $5{\mu}mol\;m^{-2}s^{-1}$의 광도로 설계된 growth chamber내에서 자엽하축의 길이생장, 자엽의 팽창, 본엽의 발생시기, 부위별 건중량 등을 측정하였다. 자엽은 유묘의 초기생장에 영향을 미쳐 자엽의 크기가 증가할수록 유묘의 생장도 좋았다. 자엽하축의 길이 생장은 $385{\mu}mol\;m^{-2}s^{-1}$ 광도에서 보다 상대적으로 낮은 광도인 32, 17, 8, $5{\mu}mol\;m^{-2}s^{-1}$에서 증가되었으나 건중량은 광도가 낮아질수록 감소되었다. 광도가 낮아짐에 따라 본엽의 발생시기가 늦어졌으며 발생수도 감소되었고, $8{\mu}mol\;m^{-2}s^{-1}$와 $5{\mu}mol\;m^{-2}s^{-1}$ 광도에서는 본엽이 발생 조차 되지 않았다. 자엽은 $385{\mu}mol\;m^{-2}s^{-1}$ 광도에서 보다 $32{\mu}mol\;m^{-2}s^{-1}$와 $17{\mu}mol\;m^{-2}s^{-1}$ 광도에서 더 많이 팽창하였지만 건중량은 적었다. 광도가 낮아짐에 따라 자엽, 자엽하축, 뿌리, 본엽의 건중량이 감소되었으며 자엽의 건중량 감소율용보다 뿌리의 감소율이 더 높아 T/R율은 급격히 증가되었다. $8{\mu}mol\;m^{-2}s^{-1}$와 $5{\mu}mol\;m^{-2}s^{-1}$ 광도에서는 뿌리가 거의 발달하지 못하였다. 본 실험을 통해 볼 때 층층나무 발아유묘의 생육가능 최저광도는 $17{\mu}mol\;m^{-2}s^{-1}$ 이상인 것으로 사료된다.

• Current Optics and Photonics
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• 제5권2호
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• pp.173-179
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• 2021

The electroluminescence (EL) intensities of GaN-based light-emitting diodes (LEDs) are estimated based on their photoluminescence (PL) properties. The PL intensity obtained under open-circuit conditions is divided into two parts: the PL intensity under a forward bias lower than the optical turn-on voltage, and the difference between the PL intensities under open-circuit conditions and under forward bias. The luminescence induced by photoexcitation under a constant forward bias lower than the optical turn-on voltage is primarily the PL from the excited area of the LED. In contrast the intensity difference, obtained by subtracting the PL intensity under the forward bias from that under open-circuit conditions, contains the EL induced by the photocarriers generated during photoexcitation. In addition, a reverse photocurrent is generated during photoexcitation under constant forward bias across the LED, and can be correlated with the PL-intensity difference. The relationship between the photocurrent and PL-intensity difference matches well the relationship between the injection current and EL intensity of LEDs. The ratio between the photocurrent generated under a bias and the short-circuit current is related to the ratio between the PL-intensity difference and the PL intensity under open-circuit conditions. A relational expression consisting of the ratios, short-circuit current, and PL under open-circuit conditions is proposed to estimate the EL intensity.

• 한국초지조사료학회지
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• 제8권1호
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• pp.61-65
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• 1988

To examine the effects of light intensity on photosynthesis, corn and sorghum species were grown under shade cloths, which reduced light intensity by 25,50 and 75%. Photosynthetic rates were measured between 10 a.m. to noon on a clear day in early and mid - summer. 1. The degree of shading had a little effect on microenvironment. Air, soil and leaf temperatures were reduced as shade increased. 2. The degree of shading in early summer had relatively a little effect on photosynthesis of corn. However, the rates of photosynthesis in mid-summer decreased by 36%, 55% with relative light intensities of 50% and 25%, respectively. 3. The rate of photosynthesis was highly correlated with light intensity. The rates of photosynthesis with relative light intensities of 75,50 and 25% were decreased by 20, 40 and 5 4% in early summer, and by 17-53%, 36-64% and 5570% in mid-summer, respectively. 4. The 75% of light intensity had relatively little effect on dry matter yield of corn and sorghum species, however dry matter yield with 50 and 25% relative light intensities was decreased 17 and 36% in corn, 13-3 1 and 50-68% in sorghum species, respectively.

• 전기학회논문지
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• 제62권9호
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• pp.1290-1296
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• 2013

The light intensity which represents the relative amount of brightness and darkness is very important feature to discern the color hue and its relevant information. With this aim, we devise a new optical system and method to analyze the light intensity. Our suggested system including a phototransistor and white-high-brightness chip light-emitting diode intend estimate the contrast value utilizing Image Research Institute(I.R.I.) Hue & Tone samples which includes 120 color sheets arranged by the color hue and tone. As a result, we confirmed that the brightness of the color checker can be accurately estimated by a high-brightness light-emitting-diode optical system.

• Journal of Microbiology and Biotechnology
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• 제16권8호
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• pp.1222-1228
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• 2006

Two kinds of Haematococcus pluvialis cells (green vegetative cells cultivated under optimal cell culture conditions and red cyst cells maintained under high light stress conditions to induce astaxanthin production) were used to investigate the protein expression profiles by two-dimensional electrophoresis, image analysis, and peptide mass fingerprinting. The cellular accumulation of astaxanthin was evident after exposure to high light intensity and reached the maximum cellular level after 78 h of high light stress. In a 2-D electrophoresis analysis, 22 proteins were upregulated over 2-fold in the red cyst cells when compared with the green vegetative cells and selected for further analysis by chemically assisted fragmentation (CAF)-MALDI-TOF sequencing to identify the protein functions. Among 22 different spots, several key enzymes specific to the carotenoid pathway, including isopentenyl pyrophosphate isomerase (IPP) and lycopene $\beta$-cyclase, appeared in H. pluvialis after exposure to high light intensity. Therefore, IPP and lycopene $\beta$-cyclase would appear to be involved with carotenoid accumulation in the cytoplasm, as these peptides were preferentially upregulated by high light intensity preceding an increase in carotenoid, and only these forms were detected in the red cyst cells.

• Journal of Ginseng Research
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• 제12권1호
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• pp.11-29
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• 1988

온도 및 광도가 인삼의 광합성 및 호흡에 미친 영향을 검토하였던 바 그 결과를 요약하면 다음과 같다. 1. 온도 및 광도와 인삼잎의 광합성간에는 고도로 유의한 2차곡선회귀가 인정되었으며 광합성에 대한 온도와 광도의 효과간에는 고도로 유의한 교호작용이 인정되었다. 2. 광도의 상승에 따르는 광합성 증가율은 온도가 높아질수록 현저한 감소를 보였고 광보상점은 온도에 따라 현저한 차이를 보였으며 각 온도의 평균 광보상점은 약 600lux였다. 그리고 고려인삼의 경우 최대광합성온도는 $15^{\circ}C$ 및 $20^{\circ}C$에서는 11,000lux였고 $25^{\circ}C$ 이상에서는 9,500lux내외였다. 3. 온도의 상승에 따르는 광합성의 감소율은 광도를 높일수록 현저히 크게 나타났으며 광합성 최적온도는 15~$22^{\circ}C$로서 광도를 높일수록 최적온도는 현저히 낮아지는 경향을 보였다. 4. 투광율 15% 일복하에서 생육한 잎의 광합성량이 가장 높았고 5% 투광율에 비해 30% 투광율에서 생육된 잎의 호흡량이 현저히 많았으며 또한 온도가 높을수록 호흡량은 현저히 증가되었다. 5. 호흡율은 고온에서 높았고 광도가 높을수록 낮아졌으며 일복하의 투광율이 높아질수록 현저히 증가되었다. 6. 일중 최대 $CO_2$ 흡수는 5% 및 15% 투광일복하에서 오전 9시 그리고 20% 투광일복하에서는 오전 7~9시경에 일어났으며 투광율이 높은 일복하에서 $CO_2$ 흡입 기간은 현저히 길었다. 7. 인삼잎의 광합성에 있어서 $CO_2$ 보상점은 130ppm이었다.

• International Journal of Control, Automation, and Systems
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• 제3권1호
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• pp.130-136
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• 2005

A new optical digitizing system for determining the position of a cursor in three dimensions(3D) and an experimental device for its measurement are presented. A semi-passive system using light intensity modulation, a technology that is well known in radar ranging, is employed in order to overcome precision limitations imposed by background light. This system consists of a charge-coupled device camera placed before a rotating mirror and a light-emitting diode whose intensity is modulated. Using a Fresnel pattern for light modulation, it is verified that a substantial improvement of the signal to noise ratio is realized for the background noise and that a resolution of less than a single pixel can be achieved. This opens the doorway to the realization of high precision 3D digitized measurement. We further propose that a 3D position measurement with a monocular optical system can be realized by a numerical experiment if a linear-period modulated waveform is adopted as the light-modulating one.

• 전기의세계
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• 제19권6호
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• pp.8-12
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• 1970

A Device is described which intensity modulates a light beam at modulating frequency in the M/W region. A Method of designing a practical crystalline microwave-Freg. light modulator has been described. In addition, Electrooptic properties and operation as light modulator of NH$_{4}$H$_{2}$po$_{4}$ is described. A light path is provided through the crystal into a suitably oriented analyzer. The intensity of the light beam emerging from the latter varies at the same rate as the cavity frequency.

• 한국보건간호학회지
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• 제32권2호
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• pp.319-330
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• 2018

Purpose: This study was conducted to determine if physical activity levels relieve the risk of development of metabolic syndrome (Mets) according to smoking intensity among smoking men. Methods: Secondary data from the 2010-2015 Korea National Health and Nutrition Examination Survey were used for this cross sectional study. A total of 3,027 men over the age of 19 were included for data analysis. Complex samples logistic regression was used to analyze the combined effects of smoking and physical activity on Mets. Smoking intensity was categorized as light (${\leq}20cigarettes/day$) or heavy (> 20 cigarettes/day), while physical activity was categorized as light (< 600 metabolic equivalent [MET]-min/week), moderate (600-3,000 MET-min/week), and vigorous (${\geq}3,000MET-min/week$). Results: Mets was less prevalent among light smokers with vigorous physical activity (Adjusted Odds Ratio [AOR]: 0.632, 95% Confidence Interval [CI]: 0.475-0.840) compared to those with light physical activity. Among heavy smokers, physical activity level was not significantly associated with Mets. Conclusion: Only vigorous physical activity exerted protective effects against development of Mets among low intensity smokers. For high intensity smokers, lowering smoking intensity and smoking cessation are also necessary to prevent development of Mets.

• 한국수산과학회지
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• 제41권6호
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• pp.446-451
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• 2008

The growth of Porphyridium cruentum and its porphyran polysaccharide production were measured as functions of light intensity, temperature, light quality (fluorescent, blue, red, and green) and nitrate concentration. The optimum light intensity, temperature, and nitrate concentration for the growth of Porphyridium cruentum and for its polysaccharide production were 1,400 lx, $25^{\circ}C$, and 0.03%, respectively. The maximum cell concentration and polysaccharide content under the optimum conditions were 1.95 and 0.23 mg/mL, respectively. Light quality did not influence growth or polysaccharide production. The best results for growth and polysaccharide production were obtained using fluorescent light.