• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.6
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• pp.487-494
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• 2006

The effects of water temperature, salinity and irradiance on the growth of harmful algae Chattonella marina isolated from Gamak Bay in South Sea, Korea were investigated. C. marina was able to grow in temperatures of $15-30^{\circ}C$ and salinities of 10-35 psu. Maximum specific growth rate (0.64/day) was observed with combination of $25^{\circ}C$ and 25 psu. Optimal growth (${\ge}70%$ of maximum specific growth rate) was obtained with all salinities of the above $20^{\circ}C$. This result indicated that C. marina is a stenothermal of the high water temperature and euryhaline organism. C. marina was did not grow at irradiance ${\le} 10{\mu}mol$ photons/($m^2\;s$). Photoinhibition did not occur at $300{\mu}mol$ photons/($m^2\;s$), which was the maximum irradiance used in this study. The irradiance-growth curve was described as ${\mu}=0.78(I-11.4)/(I+34.1)$ at $25^{\circ}C$ and 25 psu. The half-saturation photon flux density (PFD) ($K_s$) was $56.9{\mu}mol$ photons/($m^2\;s$) and compensation PFD ($I_c$) was $11.4{\mu}mol$ photons/($m^2\;s$). The result of the present study indicate that C. marina has advantage physiological characteristic to the interspecific competition at the embayment and costal areas of South and West Sea, Korea in summer.

• Journal of Plant Biotechnology
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• v.7 no.1
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• pp.67-74
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• 2005

To overcome various disadvantages of conventional cul-ture vessels for micropropagation, a novel disposable vessel, the 'Vitron', made of a multi-layered $OTP^{(R)}$ film and supported by a polypropylene frame, was developed. The film possesses superior properties such as: high light transmittance, low water vapor transmittance and thermal stability and in particular, high gas-permeability. Single nodal explants, which were excised from the multiple shoots derived from shoot-tip culture, were cultured in Vitron and polycarbonate vessels on $3\%$ sugar-containing agar on MS medium and placed at 3000 ppm $CO_2$-enrichment at a low photosynthetic photon flux density (PPFD) ($45{\mu}mol\;m^{-2}\;s^{-1}$). The in vitro and ex vitro growth, and the net photosynthetic rate of in vitro and ex vitro plantlets were significantly enhanced in the Vitron compared to those cultured in a polycarbonate vessel. Explants that were cultured on the same MS medium under low PPFD at various $CO_2$ concentrations were also cultured at 3000 ppm $CO_2$- enrichment at various PPFD: 30, 45, 60, 75 and $90{\mu}mol\;m^{-2}\;s^{-1}$. The best in vitro and ex vitro growth obtained for 3000 ppm $CO_2$-enrichment at $75{\mu}mol\;m^{-2}\;s^{-1}$ PPFD. The novel Vitron vessel, when placed under the two conditions, may replace conventional culture vessels for the successful micropropagation of sweetpotato.

• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.395-403
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• 2013

Plant factory has drawn attention in many countries in the world due to capability of environmental control not only for better yield and quality, but also for increase in functional and medicinal components of the products. In this paper, an experimental plant factory was constructed for various tests under different environmental conditions, and the operations were evaluated. A production room was constructed with adiabatic materials with dimensions of $6,900{\times}3,000{\times}2,500$ mm ($L{\times}W{\times}H$). Four sets of $2,890{\times}600{\times}2,320$ mm ($L{\times}W{\times}H$) production frame unit, each with 9 light-installed beds and an aeroponic fertigation system, resulting in 36 beds, were prepared. Accuracy and response were evaluated for each environmental control component with and without crops. Air temperature, humidity, $CO_2$ concentration, light intensity, frequency, and duty ratio, fertigation rate and scheduling were controllable from a main control computer through wireless communication devices. When the plant factory was operated without crop condition, the response times were 8 minutes for change in temperature from 20 to $15^{\circ}C$ and 20 minutes from 15 to $20^{\circ}C$; 7 minutes for change in humidity from 40 to 65%; and 4 minutes for change in $CO_2$ concentration from 450 to 1000 ppm. When operated for 24 hours with crop cultivation; average, maximum, and minimum values of temperatures were 20.06, 20.8, and $18.8^{\circ}C$; humidity were 66.72, 69.37, and 63.73%; $CO_2$ concentrations were 1017, 1168, and 911 ppm, respectively. Photosynthetic Photon Flux Density was increased as the distance from the light source decreased, but variability was greater at shorter distances. Results of the study would provide useful information for efficient application of the plant factory and to investigate the optimum environment for crop growth through various experiments.

• ALGAE
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• v.21 no.3
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• pp.311-316
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• 2006

The effects of light quality and irradiance on the growth of Cochlodinium polykrikoides were investigated in the laboratory. At 25°C and 30 psu the irradiance-growth curve was described as μ = 0.34 (I-9.76)/(I+12.5), (r=0.98). This suggests half-saturation photon flux density (PFD) (Ks) of 32.0 μmol photons m–2 s–1, and a compensation PFD (Ic) of 9.76 μmol photons m–2 s–1. Because the Ic equates to a depth of ca. 15.4 m, these responses suggest that irradiance at the depth around and below the thermocline in Yeosuhae Bay would provide favorable conditions for C. polykrikoides. Photoinhibition did not occur at 300 μmol photons m–2 s–1, which was the maximum irradiance used in this study. Blue (450 nm), yellow (590 nm) and red (650 nm) light had different effects on the growth of C. polykrikoides: it grew well under blue light, but not under yellow light. This implies that C. polykrikoides is more likely to cause an outbreak of red tide in the open sea where blue-green wavelengths predominate, rather than in enclosed water bodies where suspended particles absorb most of the blue wavelengths, and yellow-orange wavelengths predominate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.533-542
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• 2011

Numerous seagrass habitat restoration projects have been attempted recently due to the remarkable decline in seagrass coverage. Seagrass transplants tend to adapt to a new environment after experiencing transplanting stress during the early stages of transplantation. Once acclimated, the transplants grow into healthy seagrass beds via vegetative propagation. The establishment and growth dynamics of transplanted seagrasses in bays and coasts are widely reported, but few studies have been conducted on estuaries in Korea. We transplanted Zostera marina in November 2007 and November 2008 in the Nakdong estuary using the staple method, and monitored the survival, adaptation, and growth dynamics of the transplants as well as environmental factors every month for 1 year. Both transplants adapted well to the new environment without initial losses and showed rapid productivity during early summer. However, density of transplants increased 320% in 1 year from the previous year's transplants but that decreased to 59% during the following year. This significant reduction in density in the second year may have been caused by exposure to low salinity (10 psu) for 3 weeks during the unusually long monsoon season. While the survival and growth dynamics of seagrass transplants planted in bays and coasts are mainly controlled by underwater photon flux density and water temperature, salinity was the critical factor for those planted in Nakdong estuary.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.218.2-218.2
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• 2014

그래핀은 높은 전기 전도도와 열전도도, 기계적 강도를 가지고 있고 동시에 높은 전자이동도($200,000cm^2{\cdot}V{\cdot}^1{\cdot}s{\cdot}^1$) 특성을 갖는 물질로써 차세대 소재로 각광받고 있다. 하지만 그래핀을 소자에 응용하기 위해서는 전사공정과 lithography 공정 과정에서 발생되는 PMMA(Poly methyl methacrylate) residue를 완벽하게 제거해야 하는 문제점이 있다. 특히, lithography 공정 중 완벽하게 PMMA residue 가 제거되지 않고 잔류해 있을 경우에 소자의 life time, performance에 악영향을 준다는 보고가 있다. 이와같은 문제를 해결하기 위해 화학적 cleaning, 열처리를 통한 cleaning, 전류 인가에 의한 cleaning과 같은 방법들을 이용하여 그래핀의 PMMA residue를 제거하는 공정들이 보고되고 있지만, 화학적 cleaning 방법의 경우 chloroform 이라는 독성물질 사용으로 인해 산업적으로 응용이 어렵고, 열처리 방법은 전극 등의 금속이 $200^{\circ}C$ 이상의 높은 온도에서 장시간 노출될 경우 쉽게 손상을 입으며, 전류 인가에 의한 cleaning 방법은 국부적으로만 효과를 볼 수 있기 때문에 lithography 공정 후 PMMA residue를 효과적으로 제거하기에는 한계를 보이고 있다. 본 연구에서는 Ar을 이용하는 Ion beam 시스템을 통해 beam energy를 제어함으로써 PMMA residue를 효과적으로 제거하는 연구를 진행하였다. 최적화된 플라즈마 발생 조건을 찾기 위해 QMS(Quadrupole Mass Spectrometer)를 이용하여 입사하는 ion energy와 flux 양을 컨트롤 하였고, 250 W에서 최적화된 ion energy distribution 영역이 존재한다는 것을 확인할 수 있었다. 또한, 25 Gauss 정도의 electro-magnetic field를 이용하여 Ar의 ion energy를 10 eV 이하로 낮추어 damage를 최소화함으로써 효과적으로 그래핀을 cleaning 할 수 있었다. Cleaning과정에서 ion bombardment에 의해 발생한 damage는 $250^{\circ}C$에서 6시간 동안 annealing 공정을 거치면서 회복되는 것을 Raman spectroscopy의 D peak ($1335cm{\cdot}^1$) / G peak ($1572cm{\cdot}^1$) ratio 로 확인할 수 있었고, PMMA residue의 cleaning 여부는 G peak ($1580cm{\cdot}^1$)의 blue shift와 2D peak ($2670cm{\cdot}^1$)의 red shift를 통해 확인하였다. 그리고 AFM (Atomic Force Microscopy)을 이용하여 cleaning 공정과정에서 RMS roughness가 4.99 nm에서 2.01 nm로 감소하는 것을 관찰하였다. 마지막으로, PMMA residue의 cleaning 정도를 정량적으로 분석하기 위해 XPS (X-ray Photoelectron Spectroscopy)를 이용하여 sp2 C-C bonding이 74.96%에서 87.66%로 증가함을 확인을 할 수 있었다.

• Journal of Biosystems Engineering
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• v.23 no.6
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• pp.591-598
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• 1998

Light intensity and spectral characteristics of different types of fluorescent lamps were tested to investigate their possibility as the artificial lighting sources for the close illumination applied in the transplant production factory. Photosynthetic photon flux densitiy(PPF), illuminance and irradiance for all lamps decreased logarithmically with an increase of the vertical distance from the lighting source. The fluorescent lamp specially designed plant growth (PG lamp) showed a maximum spectral irradiance at the wavelength of 660nm. However, it showed lower irradiance than that of a standard fluorescent lamp at the range of wavelength between 500 and 600nm. On the other hand, PG lamp showed higher PPF and lower illuminance than those of the standard fluorescent lamp. The maximum peak of spectral characteristics for both of the single and twin three-bind fluorescent lamps was shorn at the wavelength of 545m and the next peaks were shown at the wavelength of 610nm and 435nm, respectively. Since the red fluorescent lamp has a narrower peak at the wavelength of 660nm, it may be useful for the supplementary red lighting. For three of standard, single three-band and twin three-band fluorescent lamps, the values of conversion factor for converting illuminance to PPF fell within the narrow range from 76 to 791x/$\mu$molㆍm$^{-2}$ ㆍs$^{-l}$ . However, for PG lamp, it was 29.71x/$\mu$molㆍm$^{-2}$ ㆍs$^{-1}$. Also, the values of conversion factor for converting PPF to irradiance of fluorescent lamp used in this study ranged between 4.85 and 5.34$\mu$molㆍm$^{-2}$ ㆍs$^{-1}$/Wㆍm$^{-2}$ .

• Journal of Biosystems Engineering
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• v.38 no.4
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• pp.279-286
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• 2013

Purpose: This study was conducted to analyze the utilization efficiencies of electric energy and photosynthetically active radiation of lettuce grown under red LED, blue LED and fluorescent lamps with different photoperiods. Methods: Red LED with peak wavelength of 660 nm and blue LED with peak wavelength of 450 nm were used to analyze the effect of three levels of photoperiod (12/12 h, 16/8 h, 20/4 h) of LED illumination on light utilization efficiency of lettuce grown hydroponically in a closed plant production system (CPPS). Cool-white fluorescent lamps (FL) were used as the control. Photosynthetic photon flux, air temperature and relative humidity in CPPS were maintained at 230 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, $22/18^{\circ}C$ (light/darkness), and 70%, respectively. Electric conductivity and pH were controlled at 1.5-1.8 $dS{\cdot}m^{-1}$ and 5.5-6.0, respectively. The light utilization efficiency based on the chemical energy converted by photosynthesis, the accumulated electric energy consumed by artificial lighting sources, and the accumulated photosynthetically active radiation illuminated from artificial lighting sources were calculated. Results: As compared to the control, we found that the accumulated electric energy consumption decreased by 75.6% for red LED and by 70.7% for blue LED. The accumulated photosynthetically active radiation illuminated from red LED and blue LED decreased by 43.8% and 33.5%, respectively, compared with the control. The electric energy utilization efficiency (EEUE) of lettuce at growth stage 2 was 1.29-2.06% for red LED, 0.76-1.53% for blue LED, and 0.25-0.41% for FL. The photosynthetically active radiation utilization efficiency (PARUE) of lettuce was 6.25-9.95% for red LED, 3.75-7.49% for blue LED, and 2.77-4.62% for FL. EEUE and PARUE significantly increased with the increasing light period. Conclusions: From these results, illumination time of 16-20 h in a day was proposed to improve the light utilization efficiency of lettuce grown in a plant factory.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.600-606
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• 2014

The objective of this study was to determine the effects of seedling ages of scions and rootstocks for grafting and light intensity during their cultivation in a closed transplant production system on the growth and development of grafted cucumber transplants. Cucumber scions and rootstocks were cultivated under 5 photosynthetic photon flux (PPF) levels: 100, 140, 180, 230, and $280{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ in a closed transplant production system. The scions were grafted onto the rootstocks at 8, 9, 10, 11, and 12 days after sowing (DAS). Hypocotyl length of scions and rootstocks decreased significantly as PPF increased, and an increase in dry weight with increasing PPF was more pronounced in scions. After grafting, cucumber transplants were grown in a greenhouse until 22 DAS and were then transplanted for investigation of their growth and development. Plant height, leaf area, and fresh weight of cucumber transplants grafted at 8, 9, and 10 DAS were greater, but light intensity during cultivation of scions and rootstocks did not significantly affect the early growth of cucumber transplants after grafting. The number of female flowers in grafted cucumber after transplanting was highest when scions and rootstocks were cultivated under PPF 140 and $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and were grafted at 8 DAS. These results indicate that controlling environmental conditions in a closed transplant production system during the production of scions and rootstocks can advance grafting time and promote the growth and development of grafted cucumber transplants.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.799-804
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• 2007

Oil spill caused severe effects on the marine fauna and flora due to direct contact of organisms with the oil and even in regions not directly affected by the spill. This study was conducted to understand the effects of the oil spill accidents and the use of dispersant on the red tide of Cochlodinium polykrikoides. Crude oil produced in Kuwait, bunker-C, kerosene and diesel oil, and a chemical dispersant produced in Korea, were added with a series of 10 ppb to 100 ppm in the f/2-Si medium at $20^{\circ}C$ under a photon flux from cool white fluorescent tubes of $100\;mol\;m^{-2}\;s^{-1}$ in a 14: 10 h L:D cycle for the culture of C. polykrikoides. In low concentrations of ${\leq}$ 1 ppm of examined oils no impact on the growth of C. polykrikoides was recorded, while in high concentration of ${\geq}$ 10 ppm, cell density was significantly decreased with the range of 10 to 80% in comparison with the control. The growth of C. polykrikoides after the addition of the dispersant and the mixtures combined with oils and a dispersant of ${\geq}$ 10 ppm appeared to decrease, whereas the growth of C. polykrikoides exposed to ${\leq}$ 100 ppb showed little serious impact. However, almost all the C. polykrikoides cells were died regardless of a dispersant and combined mixtures within a few days after the addition of high concentrations.