• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.143.2-143.2
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• 2012

2012년 3월 7일부터 5월 9일까지, 총 8일간 소백산 천문대의 61cm 반사망원경에 부착된 PIXIS 2K CCD와 Johnson-Cousins의 표준필터 BVRI 4색 필터를 이용하여 접촉쌍성 VW Boo의 전 위상에 걸친 광도곡선을 획득하였다. 이 관측으로부터 7개의 극심시각(주식: 4개, 부식: 3개)을 결정하였다. 우리의 극심시각을 포함하여 여러 문헌에서 수집한 총 201개의 극심시각을 이용하여 주기분석을 수행하였다. VW Boo의 주기는 약 74년에 걸쳐 영년주기감소와 규칙적인 변화를 겪은 것으로 나타났다. 영년 주기감소율은 년간 $-1.595{\times}10^{-7}$일이며, 규칙적인 변화의 주기와 반진폭은 각각 약 29.8년과 0.00667일로 산출되었다. 영년주기감소를 질량이 큰 주성에서 반성으로의 질량이동에 의한 것으로 가정하였을 때, 그 질량이동율은 년간 $-1.26{\times}10^{-7}M_{\odot}/yr$이다. 규칙적인 변화를 제3천체에 의한 광시간 효과로 가정하여 구한 3천체의 최소 질량은 $0.19M_{\odot}$이다. Wilson-Devinney 쌍성 모형을 이용하여 우리의 BVRI 광도곡선을 분석하였다. 이 때, 광도곡선에 나타난 역 O'Connell 효과를 설명하기 위하여 흑점모형을 도입하였고, W형과 A형의 두 가지 경우를 상정하여 광도곡선 해를 산출하였다. 그 결과의 천체물리학적 의미를 논의한다.

• Journal of Ginseng Research
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• v.12 no.1
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• pp.11-29
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• 1988

This study was conducted to investigate the effect of light intensity and temperature on the photosynthesis and respiration of ginseng plant. Highly significant, second degree curvilinear regressions were recognized among the photosynthesis of ginseng leaves, light intensity and temperature. And an interaction between the effects of light intensity and temperature on the photosynthesis of ginseng leaves was found to be highly significant. The increasing rate of photosynthesis with the increase of light intensity was markedly decreased with increasing temperature. The light compensation point of ginseng leaves was significantly varied with temperature, and the average point was approximately 600 lux. The light saturation point of Korean ginseng was 11,000 lux at $15^{\circ}C$ and $20^{\circ}C$ and around 9,500 lux at above $25^{\circ}C$. The decreasing rate of photosynthesis with the increase of temperature significantly increased with increasing light intensity. The optimum temperature for the photosynthesis of ginseng leaves was about 15 to $22^{\circ}C$ and markedly decreased with increasing light intensity. The highest photosynthesis occurred in ginseng leaves grown with the shade of 15% transmittance. The respiration of ginseng leaves increased with the shade of 5% and/or 30% transmittance. High temperature stimulated the respiration of ginseng leaves. Percent respiration to photosynthesis of ginseng leaves grown with the shade was increased at high temperature and decreased with increasing light Intensity. It was also increased with increasing transmittance. The maximum $CO_2$ absorption of ginseng leaves grown with the shade of 5Ps and ISVS transmittance accurred at 9 o'clock a.m., whereas that of 20% transmittance occurred at 7-9 o'clock a.m. The duration of $CO_2$ absorption was distinctively long with the shade of high transmittance. The $CO_2$ compensation point in the photosynthesis of ginseng leaves was 130 ppm.

• Korean Journal of Optics and Photonics
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• v.7 no.2
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• pp.136-141
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• 1996

We present a novel description of TE nonlinear guided waves in planar waveguides with two nonlinear bounding thin films. The nonlinear dispersion relations of the nonlinear waveguides are obtained by adopting the nonlinear transfer matrix. The optical properties obtained from these equations include: the power dependence of mode indices, the transition of the field maximum location, and the power distribution. The planar waveguide with self-focusing nonlinear layers shows the optical bistability of power-dependent mode indices, and the critical powers for the optical bistability increase with decreasing thickness of the nonlinear layers. The power distributions display the optical bistabilities, similar to those of nonlinear Fabry-Perot etalon.

• Journal of Korea Foresty Energy
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• v.19 no.1
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• pp.20-29
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• 2000

This study was carried out to investigate the effects of shading on the growth of 1 -year-old seedlings of Cornus controversa. The height growth was highest in relative light intensities of 100% and 50%, but relative growth rate in 50% was higher than that in 100% treatment. The growth did not occur under 9% relative light intensity. The root collar diameter growth at different light intensities is similar to height growth. The leaf area was highest in 50% relative light intensity, and the leaf area under the light intensity was small compared with the control. SLA and LAI of seedlings increased with decreasing relative light intensity. The LAR and LWR of seedlings increased with decreasing light intensity, but LWR decreased at 9% relative light intensity. The dry weight of root, stem, leaf and branch, and the number of branch and leaf decreased with decreasing relative light intensity. T/R ratio was highest in 17% and 30% relative light intensity. Lateral root growth decreased with decreasing light intensity except for that in 50% light intensity.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.2
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• pp.80-85
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• 2002

This study was conducted to investigate the effects of night illumination on the growth and yield of sesame(Sesamum indicum) and perilla(Perilla frutescens). Stem length and height of the first pod in sesame increased, whereas number of branch was reduced and flowering date and maturing date delayed as light intensity of night illumination increased. Number of capsules per plant, ripening ratio and seed yield of sesame were reduced as light intensity of night illumination increased. Yield reduction was greater in Ahnsankkae than in Sodunkkae. Number of nodes increased under night illumination in perilla. Two test cultivars showed reduction in number of branch at 6~10 Lx(22 ㎽ m$^{-2}$ ) intensity of night illumination, even though there was a variation between cultivars. Perilla was sensitive to night illumination far flowering and ripening. Flowering date was delayed by 21 to 28 days at 6~10 Lx intensity of night illumination. Number of flower clusters, number of seeds per flower cluster, and 1,000-seed weight in perilla were significantly reduced and seed yield was reduced by 89 to 98% at 6-10 Lx intensity of night illumination.

• Journal of Korea Foresty Energy
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• v.19 no.1
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• pp.7-12
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• 2000

This study was carried out to investigate the effect of light intensity on the growth and biomass production of Pinus thunbergii seedlings. The experiment was performed under five different light intensities such as 100, 50, 30, 10, and 25 of the natural full sun light intensity for 2 year in the field condition. The seedling showed the highest height and root collar diameter growth under natural full sun light. The height growth of the seedling under 50% of light intensity showed 96.4% of the control seedling in the first year, and 88.9% in the second year, and the root collar diameter growth showed 94.1% in the first year 77.6% in the second year. Height and root collar diameter growth was markedly reduced below 30% of relative light intensity, and the reduction rate of root collar diameter growth was higher than that of height growth. All the tested seedlings died under 2% of relative light intensity in the second year. Biomass production was also reduced by decreasing of relative light intensity, the reduction rate of root biomass production in both first and second years was higher than that of leaf or shoot biomass production. The lowest reduction was observed at the shoot in the first year, and at the leaves in the second year The highest T/R ratio was recorded by 3.55 in the seedling under 50% of relative light intesity in the first year, and by 4.88 under 10% of relative light intensity in the second year.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.439-442
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• 2009

해상용 200mm 등명기를 대체하기 위해 2003년 최초로 국내에서 LED 등명기가 개발되었다. LED 등명기는 개발되어진 이래로 그 수요가 계속 증가하고 있으며, 기능 또한 많이 개선되어지고 있다. 그러나 현재까지 LED 등명기에 관한 심도 있는 분석이 이루어지고 있지 않다. 본 논문은 LED 등명기의 사용전검사시 색상별 부동광도 및 정기검사(3년) 시 부동광도 감소율 등을 통계조사를 통해 알아보고, 현재 진행중인 LED 등명기 수명실험의 2차년도까지의 결과를 토대로 현단계에서의 개선점을 찾아보기 위해 작성되었다. 또한 향후 계속적인 LED 등명기 성능 기선 연구에 기초자료를 제공하고자 한다.

• Journal of Ginseng Research
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• v.12 no.1
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• pp.30-39
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• 1988

This study was conducted to investigate the effects of light intensity and temperature on the physiological characteristics and growth of ginseng leaves. The higher the transmittance of the shade, the greater the area was decreased. In contrast, however, the amount of transpiration was increased. There was no significant difference in the number of stomata, but the size of stomata was distinctively decreased. The higher the transmittance of the shade, the more the contents of total chlorophyll, chlorophyll a and b, and cartooned were decreased. In contrast, however, the aye ratio of chlorophyll was increased. Regardless of temperature, the contents of chlorophyll providing maximum photosynthesis at the end of June and August were 2.1mg and 1 8mg/g F.W. respectively.

• Journal of Bio-Environment Control
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• v.19 no.1
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• pp.36-48
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• 2010

This present study was conducted to investigate photosynthetic characteristics, chlorophyll fluorescence, chlorophyll contents of Betula platyphylla var. japonica, Prunus leveilleana, Magnolia sieboldii, growing under four different light intensity regimes (full sun, and 64~73%, 35~42%, 9~16% of full sun). As result, Betula platyphylla var. japonica showed outstanding photosynthetic capacity and apparent quantum yield in full sun and showed low shade tolerance. Prunus leveilleana showed good photosynthetic capacity and apparent quantum yield in 64~73% or 35~42% of full sun and showed common shade tolerance. However, Magnolia sieboldii showed good photosynthetic capacity and apparent quantum yield in 35~42% of full sun, while the lowest in full sun. Magnolia sieboldii showed the highest shade tolerance compared to the other species. As the shading level increased, the total chlorophyll contents of all species increased with significant difference.

• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.493-500
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• 1998

To investigate the effects of light intensity on the growth, and the critical minimum light intensity for growing of Cornus controversa seedlings at the stage of cotyledon, hypocotyl elongation, cotyledon expansion, the times of leaves appearance, dry weights of each organ, and specific leaf area(SLA) were measured on a growth chamber with several light intensity gradients(385, 32, 17, 8, and $5{\mu}mol\;m^{-2}s^{-1}$). There was a positive correlationship between the size of cotyledon and the biomass of cotyledon and total seedling. Hypocotyl was more elongated under relatively low light intensities, such as 32, 17, 8, and $5{\mu}mol\;m^{-2}s^{-1}$ than under $385{\mu}mol\;m^{-2}s^{-1}$ light intensity, however, dry weight of the hypocotyl was adverse. As the light intensities decreased, the leaf appearance was delayed and the number of leaves decresed. In addition, leaves did not appear under $8{\mu}mol\;m^{-2}s^{-1}$ and $5{\mu}mol\;m^{-2}s^{-1}$ light intensity. Although cotyledons were more fully expanded under 32 and $17{\mu}mol\;m^{-2}s^{-1}$ light intensities than $385{\mu}mol\;m^{-2}s^{-1}$ light intensity, the dry weights of cotyledons were greater under the high light intensity. The dry weight of cotyledon, hypocotyl, root and leaves showed a decreased pattern with decreasing light intensities, but root to shoot(hypocotyl+leaves) ratio rapidly increased. Roots did not develop below $8{\mu}mol\;m^{-2}s^{-1}$ light intensity. In conclusion, the results showed that the critical minimum light intensity for growing of Cornus controversa seedlings was above $17{\mu}mol\;m^{-2}s^{-1}$ light intensity.