• Korean Journal of Environmental Biology
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• v.17 no.3
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• pp.359-364
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• 1999

The effect of Salicylic acid (SA) on the leaf growth, chlorophyll content, photosynthesis, stomatal conductance in Commelina communis L. was investigated. C. communis which was grown in Hoagland solution containing 1 mM SA during 3 weeks resulted in a significant reduction of leaf length, width and area. 1 mM SA reduced about 10% of the leaf area at 1 week and 2 weeks, but inhibited 22% of the leaf area at 3 weeks. SA also showed great effect on the reduction of chlorophyll content. SA reduced 47% and 53% of chlorophyll content each at 2 weeks and 3 weeks when it was compared with the control. Chlorophyll a/b ratio in SA treated sample was increased at 3 weeks representing that SA was sensitive to chlorophyll b. The treatment of SA did not inhibit the activity of PSII＋PSI, PSII and PSI. This result indicates that SA did not show direct effect oil the photosynthetic electron transport activity. However, when C. communis was grown in Hoagland solution containing I mM SA fer long period, SA showed clear inhibition of photosyhthesis in intact leaves. The treatment of SA for 3 weeks showed about 23~65% inhibition of photosynthetic activity at various light intensity (100~1000$\mu$mo1 m­$^2$S­$^1$). Similar effect was found on stomatal conductance. The treatment of SA caused an almost closure of stomata. Similar effects of stomatal conductance at various light intensity indicate a loss of normal control on stomatal mechanism. These results indicate that the effect of SA on photo-synthetic activity was not by SA itself but by indirect metabolic pathway.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.196-207
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• 2019

This study was carried out to investigate the effects of C. japonica, D. morbifera, D. macropodum, I. anisatum, Q. glauca and R. indica To investigate the photosynthetic ability, chlorophyll content, chlorophyll fluorescence analysis, and physiological environmental. The photosynthetic rate, cancer respiration rate, stomatal conductance, and rate of evaporation tended to decrease as a result of drying stress in the no-water condition for 28 days. I. anisatum, Q. glauca and R. indica showed a low rate of less than 40% until 28 days of no-treatment. The total chlorophyll contents were decreased in the order of D. macropodum> D. morbifera> C. japonica> Q. glauca> M. thunbergii> R. indica> I. anisatum. Chlorophyll fluorescence analysis showed that there was no change in the qP, but after 28 days no $Fv/F_m$, $F_o$, $R_{fd}$, $NPQ_{_-LSS}$ can be a useful indicator for quantitative estimation within a short period of time with a marked reduction rate of PSII quantum yield ${\Phi}PSII$ in the rectified state by continuous light during the nominal adaptation period. In the case of I. anisatum, Q. glauca and R. indica If water management can be carried out at intervals, it may be possible to plant trees in trees and landscape trees.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.409-410
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• 2008

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.14-14
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• 1998

• Proceedings of the Korean Society of Potoscience Conference
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• 2002.06a
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• pp.37-37
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• 2002

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E2
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• pp.89-98
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• 2006

Two tobacco cultivars (Nicotiana tabacum L.), Bel-B and Bel-W3, tolerant and sensitive to ozone, respectively, were grown in a greenhouse supplied with charcoal filtered air and exposed to 200 ppb ozone for 4 hr. Effects on chlorophyll fluorescence, net photosynthesis, and stomatal conductance are described. Quantum yield was calculated from chlorophyll fluorescence and the initial slope of the assimilation-light curve measured by the gas exchange method. Only the sensitive cultivar, Bel-W3, developed visual injury symptoms on up to 50% of the $5^{th}$ leaf. The maximum net photosynthetic rate of ozone-treated plants was reduced 40% compared to control plants immediately after ozone fumigation in the tolerant cultivar; however, photosynthesis recovered by 24 hr post fumigation and remained at the same level as control plants. On the other hand, ozone exposure reduced maximum net photosynthesis up to 50%, with no recovery, in the sensitive cultivar apparently causing permanent damage to the photosystem. Reductions in apparent quantum efficiency, calculated from the assimilation-light curve, differed between cultivars. Bel-B showed an immediate depression of 14% compared to controls, whereas, Bel-W3 showed a 27% decline. Electron transport rate (ETR), at saturating light intensity, decreased 58% and 80% immediately after ozone treatment in Bel-B and Bel-W3, respectively. Quantum yield decreased 28% and 36% in Bel-B and Bel-W3, respectively. It can be concluded that ozone caused a greater relative decrease in linear electron transport than maximum net photosynthesis, suggesting greater damage to PSII than the carbon reduction cycle.

• ALGAE
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• v.20 no.2
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• pp.127-132
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• 2005

Algal growth potentials were probed by algal growth rates, maximal PSII quantum yields and ATP amount as well as dry weights of algae to evaluate the water fertility due to the algal growth in the stream (CT) and stagnant watershed (WW). Oscillatoria agardhii (CY) and Coelastrum reticulatum (CH) were cultured in nitrogen (N) and phosphorus (P) starvation media (CH-10 medium) and re-inoculated in CT and WW for 7 days. Cell division rates of CY were the highest (k = 7.5) in WW after N starvation, while those of CH were the hight (k = 2.97) in WW after P starvation. The growth of CY was limited by P, while that of CH was by N. Conversely, maximal PSII quantum yields of CH were generally higher than those of CY in CT and WW according to culture time. CY was much more sensibly adapted than CH according to the variations of nutrient amounts in WW. The water fertility was much higher in WW than in CT. The potential assessment tool for water fertility will be able to compensate for the limit of physio-chemical analyses and to be applied as a monitoring system to forecast red-tide.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.328-329
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• 2006

반도체 소자의 소형화, 고질적화는 junction 깊이 감소와 도핑농도의 증가를 요구한다. 현재 상용화되는 도핑법은 이온빔 주입(Ion Beam Ion Implantation, IBII)인데, 이 방법은 낮은 가속에너지를 가하는 경우 이온빔의 정류가 금속이 감소해 주입 속도가 낮아져 대랑 생산이 어렵고 장비가 고가라는 단점이 있다. 하지만 플라즈마를 이용한 이온주입법 (Plasma Source Ion Implantation, PSII)은 공정 속도가 빠르고 제조비용이 매우 저렴해 새로운 이온주입법으로 주목받고 있다. PSII법에서 플라즈마 특성은 그 결과에 큰 영향을 미치므로 플라즈마 특성의 적절한 제어가 필수적으로 요구된다. 본 연구에서는 공정압력과 RF power를 변화시키며 플라즈마 밀도 측정했다. 그 결과 공정압력이 증가함에 따라서 플라즈마 밀도는 감소되었고 RF power 증가함에 따라서 플라즈마 밀도는 증가되었다.

• Tribology and Lubricants
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• v.23 no.1
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• pp.14-18
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• 2007

SCM415 alloy was implanted with nitrogen ions using plasma source ion implantation (PSII), at a dose range of $1{\times}10^{17}\;to\;6{\times}10^{17}N^{+}cm^{-2}$. Auger electron spectrometry (AES) was used to investigate the depth profile of the implanted layer. Friction and wear tests were carried out on a block-on-ring wear tester. Scanning electron microscopy (SEM) was used to observe the micro-morphology of the worn surface. The results revealed that after being implanted with nitrogen ions, the frictional coefficient of the surface layer decreased, and the wear resistance increased with the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker oxidative wear with the increase in the nitrogen dose. The effects were mainly attributed to the formation of a hard nitride precipitate and a supersaturated solid solution of nitrogen in the surface layer.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.162-168
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• 2011

In this research, nitrogen plasma source ion implantation(PSII) of non-coated tungsten carbide endmill tools was conducted with low heat treatment for increasing wear resistance. After the low heat treatment of PSIIed tools to give a homogeneity of wear resistance, the surface modification of tools was analyzed by hardness test, surface roughness and cutting forces. As for the resultant cutting forces, low heat treatment in temperature of $400^{\circ}C$ and $500^{\circ}C$ is stable because of low cutting resistance. The 20-minutes heat treated tool at spindle speed 25000rpm has superiority of surface roughness, Ra of $0.420{\mu}m$ and was found to have good wear resistance. The higher hardness value was obtained by increasing temperature from $300^{\circ}C$ to $600^{\circ}C$ for PSIIed tools with low heat treatment. As the PSIIed tools under 10minutes at temperature of $600^{\circ}C$ have the highest hardness as Hv of 2349.8, It was analyzed that temperature processing give much influences on hardness.