• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.61-67
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• 2006

We examined seedlings of two species (Ilex rotunda and Illicium anisatum) which have a different level of shade tolerance and raised them under different light regimes (full sunlight and 50% shading). After 12 months, we investigated chlorophyll content (Chl. a, Chl. b and Chl. a+b), photosynthetic systems (photosynthetic rate, light compensation point, dark respiration rate and quantum yield), intercellular $CO_2$ concentration and water use efficiency to show acclimation reaction to different light conditions. Seedlings grown under full sunlight showed lower chlorophyll content than those in the shading regime. There was a significant difference between the full sunlight and shade treatments in I. anisatum (shade tolerance species). I. rotunda (intermediate species) showed high photosynthetic rate and water use efficiency over PPFD $1000\;{\mu}mol\;m^{-2}s^{-1}$ to full sunlight. Also, I. anisatum grown under full sunlight showed lower photosynthetic rate and water use efficiency over a range of all PPFD. This result showed that I. rotunda has a more flexible reaction system than that of I. anisatum.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.264-268
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• 1990

A guided-wave electro-optic Mach-Zehnder interferometric modulator was fabricated on X-cut LiNbO3 . The channel waveguides were formed by proton diffusion with self-aligned SiO2-cladding. A mach-Zehnder interferometric modulator with arm lengths of 7mm has been fabricated and tested at 0.6328${\mu}{\textrm}{m}$. Its modulation depth with V$\pi$ of only 3.5V was 85% and the 3dB bandwidth was 1.6KHz. For high speed operation, the electrode dimension should be reduced to have smaller R, L, and C.

• Horticultural Science & Technology
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• v.16 no.3
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• pp.364-365
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• 1998

The present study was conducted to develop a more accurate and efficient measure than any other quantifying measures of the leaf variegation when influenced by changes in certain physical and environmental factors. Through this computer quantification for two Tradescantia cultivars, it was ascertained that total leaf area decreased and extent of the leaf variegation increased as light intensity increased. According to this result to determine the brightness of the leaf, using the same aforementioned measurement, the leaf color was brightest in the sun and it become darker as light intensity decreased. High correlation was found between total leaf and leaf variegation area measured by leaf area meter and the pixel of computer graphic file through scanning. Thus, the leaf area and leaf variegation area measurement using computer graphic will be used very efficiently.

• Analytical Science and Technology
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• v.6 no.3
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• pp.307-311
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• 1993

Ionophore, which contains 5-membered heterocyclic compound, was prepared. $Mg^{2+}$ was determined by salting-out technique using ionophore as a chelating reagent. After $Mg^{2+}$ was extracted into the acetonitrile layer as a Mg-$(Ionophore)_2$ complex from acetate buffered aqueous solution by salting-out extraction technique, absorbance of complex was recorded by atomic absorption spectrophotometry. Optimum pH was between 2.5 and 5.0 for extraction and 1:2([$Mg^{2+}$]/[ionophore]) complex were formed. The range of detection was 0.24ppm~2.4ppm and $Ca^{2+}$ and EDTA were interfered in the determination of $Mg^{2+}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.2
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• pp.56-59
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• 2001

Thin films of hydrogenated amorphous silicon (a-Si : H) of different compositions were deposited on Si(100) wafer and glass by RF plasma-enhanced chemical vapor deposition (PECVD). In the present work, we have investigated the effect of the If. power on the properties, such as optical band gap, transmittance and crystallinity, of crystalline silicon thin films. Raman data show that the material consists of an amorphous and crystalline phase for the co-presence of two peaks centered at 480 and 520cm$^{-1}$. X-ray spectra confirmed of crystallites with (111) orientation at 300w The transmittance of thin films was measured by UV-VIS spectrophotometer. In addition, Si-H chemical bondings were studied by Fourier Transform Infrared (FT-IR) spectroscopy.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.474-474
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• 2013

PDMS는 미세패턴을 위해 소프트 리소그래피 널리 활용되어질 뿐만 아니라, 재질이 투명하고 탄성과 강한 내구성을 갖고 있어 유연한 광학 및 전자소자에 이용될 수 있다. 최근에는, 이러한 PDMS를 서브파장구조(subwavelength grating structure)를 형성하거나 텍스쳐(texture)표면구조를 이용한 효과적인 반사방지막(antireflection coating)기판을 제작하여 태양전지 및 디스플레이 소자의 성능을 발전시키는 연구가 활발히 진행되고 있다. 한편, 수열합성법(hydrothermal method)이나 전기화학증착법(electrodeposition method)으로 비교적 간단한 공정을 통해서 다양한 기판위에 산화아연(ZnO) 나노막대(nanorod)를 수직정렬로 성장시킬 수 있는데, 이러한 구조는 반사방지특성의 유효 굴절률 분포(effective refractive index profile)를 갖고 있기 때문에 LED나 태양전지에 성능을 개선할 수 있다. 이에 본 연구에서는 수열합성법을 통해 성장된 수직 정렬된 산화아연 나노막대를 이용한 PDMS 표면의 미세패턴 형성하여 광학적 특성을 분석하였다. 실험을 위해, 스퍼터링을 통해서 산화아연 시드층을 형성한 후, 질산아연헥사수화물과 헥사메틸렌테트라민을 수용액에 담가두어 산화아연 나노막대를 성장시켰으며, PDMS의 베이스와 경화제의 질량비를 10：1으로 용액을 준비하여 수직 정렬된 산화아연 나노막대 표면을 casting method으로 코팅하여 열경화 처리하였다. 제작된 샘플의 형태, 구조 광특성을 관찰하기 위해서 전계방출형전자현미경, X선 회절 분석기, 분광 광도계를 이용하였다.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.1
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• pp.25-32
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• 2016

This study deals with the light environments and weather conditions affecting to the night illuminance over the Korean peninsula. The experiment was executed to analyze the effects on the illuminance at separate sites(Gyeryong and Pilseung) considering the different light environments. The analysis was applied to illuminance measurement from the lightmeter, which was developed for the IYA(International Year of Astronomy) 2009, in order to observe the illuminance of areal networks. The weather observations, such as the cloud cover and visibility, were used to understand the quantitative influence of the illuminance to the selected sites. The results show that the illuminance measurements are significantly different from data of the operational illuminance prediction model which simply applies extinction effect for the illuminance. It shows that these differences are caused by the light environments and weather conditions for each site. Therefore, it can be confirmed that the night illuminance is the output of interaction with the characteristics of light for luminous sources.

• Clinical and Experimental Reproductive Medicine
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• v.16 no.1
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• pp.1-7
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• 1989

배양중인 생쥐 난자의 성숙에 미치는 배양액 내 calcim의 영향을 알아보기 위하여 1.71mM $Ca^{2+}$을 처리한 배양액과 $Ca^{2+}$이 존재하지 않는 배양액에서 난자를 배양하여 불꽃 원자 흡수 분광 광도계를 이용하여 배양된 난자의 $Ca^{2+}$농도를 측정하였다. 1) $Ca^{2+}$처리한 배양액에서 배양된 cumulus-cell이 제거된 (denuded oocyte)난자들은 시간이 지남에 따라 $Ca^{2+}$농도가 높게 나타났고, 2) $Ca^{2+}$처리하지 않은 배양액에서는 denuded난자는 3시간째 배양될때 부터 $Ca^{2+}$양이 줄어 들었다. Cumulus-enclosed난자는 $Ca^{2+}$존재하에서는 GVBD가 일어났다고 생각되는 4시간까지 계속 증가를 보인 반면 $Ca^{2+}-free$에서는 배양되지 않은 난자와 거의 차이가 없게 나타났다. 3) 핵막붕괴가 일어난 후부터 15시간까지 배양시컸을 때에는 CEO와 denuded oocyte에서 공히 $Ca^{2+}$의 농도는 다시 증가된 상태로 계속 되었다. 이런 결과로 미루어 보아 난자 성숙시 부터 성숙과정이 끝날때가지 exteral $Ca^{2+}$이 요구되고 있음을 증명해 주고있다. 그러나 이러한 세포질내의 $Ca^{2+}$및 bound calcium이 난자 성숙시부터 어떤 역활을 하고 있는 기작에 대해서는 좀 더 연구가 있어야겠다.

• Journal of the Korean Chemical Society
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• v.41 no.6
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• pp.299-303
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• 1997

The rate constants($k_{OH}$) for the alkaline hydrolysis of the 4-substituted phenyl ethyl benzylphosphonates were determined in various buffer solutions by UV(Vis spectrophotometer. The activation entropies of the title reactions show negative values and this result is not consistent with a dissociative mechanism (EA) for which a positive or slightly negative value of the entropy of activation should be expected. An associative mechanism(AE) is favorable because the negligible negative charge is generated on the leaving group in the rate determining step from a good Hammett relationship(ρ=1.89). By the results of a kinetic study, we conclude that a dissociative mechanism is not proceeded in the title reactions.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.471-475
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• 1987

Fe(II)-poly(D-glutamic acid) (PGA) complex in aqueous solution has been investigated as functions of pH and concentration of Fe(II) by using absorption and circular dichroism spectroscopies. The helix-breaking interaction occurred at pH 4.3 while the helix-directing one occurred at pH 5.7 after forming complex between PGA and Fe(II). The relationship between conformation change of PGA by forming complex with Fe(II) and complex constants for the above system was studied. As a result, stability constants in random coil structure of PGA are larger than those in ${\alpha}$-helix structure. This result indicates that the random coil structure of PGA-Fe(II) complex shows more stable complex than ${\alpha}$-helix one.