• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.276-276
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• 2010

Localized surface plasmon resonance (LSPR) has been explored recently as a promising approach to increase energy conversion efficiency in photovoltaic devices, particularly for thin film hydrogenated amorphous silicon (a-Si:H) solar cells. The LSPR is frequently excited via an electromagnetic (EM) radiation in proximate metallic nanostructures and its primary con sequences are selective photon extinction and local EM enhancement which gives rise to improved photogeneration of electron-hole (e-h) pairs, and consequently increases photocurrent. In this work, high-dielectric-constant (k) $ZrO_2$ (refractive index n=2.22, dielectric constant $\varepsilon=4.93$ at the wavelength of 550 nm) is proposed as spacing layer to enhance the LSPR for application to the thin film silicon solar cells. Compared to excitation of the LSPR using $SiO_2$ (n=1.46, $\varepsilon=2.13$ at the wavelength of 546.1 nm) spacing layer with Au nanoparticles of the radius of 45nm, that using $ZrO_2$ dielectric shows the advantages of(i) ~2.5 times greater polarizability, (ii) ~3.5 times larger scattering cross-section and ~1.5 times larger absorption cross-section, (iii) 4.5% higher transmission coefficient of the same thickness and (iv) 7.8% greater transmitted electric filed intensity at the same depth. All those results are calculated by Mie theory and Fresnel equations, and simulated by finite-difference time-domain (FDTD) calculations with proper boundary conditions. Red-shifting of the LSPR wavelength using high-k $ZrO_2$ dielectric is also observed according to location of the peak and this is consistent with the other's report. Finally, our experimental results show that variation of short-circuit current density ($J_{sc}$) of the LSPR enhanced a-Si:H solar cell by using the $ZrO_2$ spacing layer is 45.4% higher than that using the $SiO_2$ spacing layer, supporting our calculation and theory.

• Horticultural Science & Technology
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• v.34 no.3
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• pp.405-413
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• 2016

Quinoa (Chenopodium quinoa Willd.) is a plant native to the Andean region that has become increasing popular as a food source due to its high nutritional content. This study determined the optimal photoperiod, light intensity, and electrical conductivity (EC) of the nutrient solution for growth and yield of quinoa in a closed-type plant factory system. The photoperiod effects were first analyzed in a growth chamber using three different light cycles, 8/16, 14/10, and 16/8 hours (day/night). Further studies, performed in a closed-type plant factory system, evaluated nutrient solutions with EC (salinity) levels of 1.0, 2.0 or $3.0dS{\cdot}m^{-1}$. These experiments were assayed with two light intensities (120 and $143{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) under a 12/12 and 14/10 hours (day/night) photoperiod. The plants grown under the 16/8 hours photoperiod did not flower, suggesting that a long-day photoperiod delays flowering and that quinoa is a short-day plant. Under a 12/12 h photoperiod, the best shoot yield (both fresh and dry weights) was observed at an EC of $2.0dS{\cdot}m^{-1}$ and a photosynthetic photon flux density (PPFD) of $120{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. With a 14/10 h photoperiod, the shoot yield (both fresh and dry weights), plant height, leaf area, and light use efficiency were higher when grown with an EC of $2.0dS{\cdot}m^{-1}$ and a PPFD of $143{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Overall, the optimal conditions for producing quinoa as a leafy vegetable, in a closed-type plant factory system, were a 16/8 h (day/night) photoperiod with an EC of $2.0dS{\cdot}m^{-1}$ and a PPFD of $143{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.705-711
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• 2015

Management of soil water and fertilization is known to primarily affect physiological properties and yield in plant. The effect of soil water potential and nitrogen application on characteristics of photosynthesis and chlorophyll fluorescence in Schisandra chinensis Baillon was investigated on a sandy loam soil. Net photosyntheis rate and transpiration rate increased as a photon flux density and was highest at -50kPa of soil water potential. Light compensation point ($1.5{\mu}molm^{-1}s^{-1}$) and dark respiration ($0.13{\mu}molCO_2m^{-1}s^{-1}$) was lowest at -50 kPa but maximum photosynthesis rate ($13.10{\mu}molCO_2m^{-1}s^{-1}$) and net apparent quantum yield ($0.083{\mu}molCO_2m^{-1}s^{-1}$) was highest at -50 kPa. As results of chlorophyll fluorescence by OJIP analysis, maximum quantum yield (Fv/Fm) of photosystem II (PSII) and PIabs was higher in treatments of -50 kPa and -60 kPa respectively, which reflects the relative reduction state of PSII. But the relative activities per reaction center such as ABS/RC and DIo/RC were low with decreasing soil water potential. Net photosyntheis rate and transpiration rate were highest at treatment of soil testing 1.0 times ($92kgha^{-1}$). Application of nitrogen resulted in high Fv/Fm, $PI_{abs}$ and low ABS/RC, DIo/RC. This result implies that -50 kPa of soil water potential and nitrogen fertilizer may improve the efficiency of photosynthesis through controlling a photosystem in Schisandra chinensis Baillon.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.328-334
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• 2019

Shading paint (water-soluble) is one of the temperature control agents inside of a greenhouse in summer. Plastic film rain shelter is a unique system in Korean, prevents disease development vineyards, but it causes the heat inside a shelter in summer. Shading paint treatment with different shading rates (15, 25, and 35%) outside of plastic rain shelter avoided excessive heat inside. Shading paint influenced sunlight under plastic rain shelter in a different manner at each treatment. 35% of shading paint treatment reduced 45% of PPFD (Photosynthesis Photon Flux Density) than non-treatment control. Shading paint had the significance of efficiency to reduce the temperature under plastic rain shelter. 35% of shading paint treatment reduced $2^{\circ}C$ of bunch temperature than non-treatment control. However, shading paint treatment had not to control lower than ambient temperature. 35% of shading paint treatment is available to prevent excessive heat damage and poor fruit quality under plastic film rain shelter in summer in Korean vineyards.

• Journal of Practical Agriculture & Fisheries Research
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• v.24 no.4
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• pp.30-34
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• 2022

This study was carried out to analyze the effect of changes in the light environment caused by the daylight disturbance on the productivity and quality of the standard cut flower rose cultivar 'Monet'. It was artificially shaded to obstruct the sunlight and the productivity and growing characteristics of roses according to the time of daylight disturbance were investigated. The number of cut flowers per unit area (3.3m²) of the cut flower rose 'Monet' was 40 stems in the control, while in the 4-hour, 8-hour, and 12-hour treatments, it was 32, 29, and 25, respectively. As the daylight disturbance time was increased, the number of cut flowers showed a tendency to decrease. In the case of cut flower characteristics related to the quality of cut roses, all characteristics such as flower width, flower height, petal length, and petal width, decreased by 10 to 20% in the 12-hour treatment compared to the control. In addition, growth characteristics such as peduncle length, peduncle thickness, and cut flower height, which determine the marketability of cut roses, also tended to decrease as the daylight disturbance time increased. On the other hand, the number of days to flowering increased by 14.0% from 24.3 to 27.7. The overall growth characteristics were contracted and flowering was delayed as the time of daylight disturbance increased. In the results of this study, as the daylight disturbance time increased, flower size, cut flower length, and fresh weight was decreased. This is due to the decrease in the total photosynthetic amount as the daily average photosynthetic photon flux density (PPFD) was decreased, resulting in a decrease in the quality of roses. It is judged that it is because they do not receive enough carbohydrates necessary for growth and development.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.212-220
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• 2022

When it comes to single node leafy stem cuttings of rose (Rosa hybrida), environmental management such as air temperature, relative humidity, and light affect productivity. In order to investigate the effect of air temperature and relative humidity on the cutting success rate and rooted cuttings quality, a transparent airtight box was used to implement a closed system. We have also tried to find out the most effective photoperiod and the number of leaflets in closed system using artificial light (white LED, 104.0 µmol·m^-2·s^-1 photosynthetic photon flux density). The first experiment was conducted for a total of 6 weeks under 4 airtight period conditions. The number of roots and longest root length decreased as the airtight period increased. But there were no significant differences in the survival rate, shooting rate, and rooting rate according to airtight periods. In the second experiment the results indicated that survival and shooting rate were significantly affected by the photoperiod (0/24, 2/22, 4/20, 8/16, and 16/8 h), the number of leaflets (0, 2, and 4 leaflets) of the cuttings and their interaction. The survival rate was the highest in the 16-h day length and 4 leaflets. By considering survival rate and shooting rate with energy efficiency, the 8-h day length and 2 or 4 leaflets were judged to be the most effective.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.12a
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• pp.61-61
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• 2020

This experiment was carried out using artificial bed soil and LED in the plastic film house(irradiation time: 07:00-17:00/day). Seedlings(n=63 per 3.3 m²) of ginseng was planted on May 17, 2018. LED was combined with red and blue light in a 3:1 ratio and irradiated with different light intensity(40-160 µmol/m²/s). Average air temperature from April to September according to the light intensity test was 20.4℃-20.9℃. Average artificial bed soil temperature was 20.1℃-21.7℃. The test area where fluorescent lamp was irradiated tended to be somewhat lower than the LED irradiation area. The chemical properties of the test soil was as follows. pH levels was 6.6-6.7, EC levels 0.9-1.3 dS/m and OM levels 30.6-32.0%. The available P₂O₅ contents was 73.3-302.3 mg/kg. Exchangeable cations K and Ca contents were higher than the allowable ranges and mg content was high in the fluorescent lamp treatment. The photometric characteristics of LED light intensity are as follows. The greater the light intensity, the higher the PPFD(Photosynthetic Photon Flux Density) value, illuminance and solar irradiation. Fluorescent lamp treatment had high illuminance value, but PPFD and solar irradiation were lower than LED intensity 40 µmol/m²/s treatment. The photosynthetic rate increased(2.0-3.8 µmolCO²/m²/s) as the amount of light intensity increased, peaking at 120 µmol/m²/s, and then decreasing. The SPAD (chlorophyll content) value decreased as the amount of light intensity increased, and was the highest at 36.1 in fluorescent lamp treatment. Ginseng germination started on April 5 and took 14-17 days to germinate. The overall germination rate was 68.8-73.6%. The growth of aerial parts(plant height etc.) were generally excellent in the treatment of light intensity of 120-160 µmol/m²/s. The plant height was 41.9 cm, stem length was 24.1 cm, leaf length was 9.8 cm and stem diameter was 5.6 mm. The growth of underground part (root length etc.) was the best in the treatment with 120 µmol/m²/s of light intensity. Due to the root length was long(24.8 cm) and diameter of taproot was thick(18.7 mm), the fresh root weight was the heaviest at 24.8 g. There were no disease incidence such as Alternaria blight, Gray mold and Anthracnose. Disease of Damping-off caused by Rhizoctonia solani occurred 0.6-1.5% and incidence ratio of rusty root ginseng was 30.8-62.3%. It is believed that the reason for the high incidence of rusty root ginseng is that the amount of field moisture capacity of artificial bed soil is larger than the soil. Leaf discoloration rate was 13.7-32.3%.

• The Korean Journal of Nuclear Medicine
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• v.39 no.3
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• pp.182-190
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• 2005

Purpose: There are differences between Standard Uptake Value (SUV) of CT attenuation corrected PET and that of $^{137}Cs$. Since various causes lead to difference of SUV, it is important to know what is the cause of these difference. Since only the X-ray CT and $^{137}Cs$ transmission data are used for the attenuation correction, in Philips GEMINI PET/CT scanner, proper transformation of these data into usable attenuation coefficients for 511 keV photon has to be ascertained. The aim of this study was to evaluate the accuracy in the CT measurement and compare the CT and $^{137}Cs$-based attenuation correction in this scanner. Methods: For all the experiments, CT was set to 40 keV (120 kVp) and 50 mAs. To evaluate the accuracy of the CT measurement, CT performance phantom was scanned and Hounsfield units (HU) for those regions were compared to the true values. For the comparison of CT and $^{137}Cs$-based attenuation corrections, transmission scans of the elliptical lung-spine-body phantom and electron density CT phantom composed of various components, such as water, bone, brain and adipose, were performed using CT and $^{137}Cs$. Transformed attenuation coefficients from these data were compared to each other and true 511 keV attenuation coefficient acquired using $^{68}Ge$ and ECAT EXACT 47 scanner. In addition, CT and $^{137}Cs$-derived attenuation coefficients and SUV values for $^{18}F$-FDG measured from the regions with normal and pathological uptake in patients' data were also compared. Results: HU of all the regions in CT performance phantom measured using GEMINI PET/CT were equivalent to the known true values. CT based attenuation coefficients were lower than those of $^{68}Ge$ about 10% in bony region of NEMA ECT phantom. Attenuation coefficients derived from $^{137}Cs$ data was slightly higher than those from CT data also in the images of electron density CT phantom and patients' body with electron density. However, the SUV values in attenuation corrected images using $^{137}Cs$ were lower than images corrected using CT. Percent difference between SUV values was about 15%. Conclusion: Although the HU measured using this scanner was accurate, accuracy in the conversion from CT data into the 511 keV attenuation coefficients was limited in the bony region. Discrepancy in the transformed attenuation coefficients and SUV values between CT and $^{137}Cs$-based data shown in this study suggests that further optimization of various parameters in data acquisition and processing would be necessary for this scanner.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.191-199
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• 2018

Purpose : In this study, we evaluated the usefulness of colloid gel(slime) as a compensator for irregular patient surfaces in radiation therapy. Materials and Methods : For this study, colloid gel suitable for treatment was made and four experiments were conducted to evaluate the applicability of radiation therapy. Trilogy(Varian) and CT(SOMATOM, Siemens) were used as treatment equipment and CT equipment. First, the homogeneity according to the composition of colloid gel was measured using EBT3 Film(RIT). Second, the Hounsfield Unit(HU) value of colloid gel was measured and confirmed by CRIS phantom, Eclipse RTP(Eclipse 13.1, Varian) and CT. Third, to measure the deformation and degeneration of colloid gel during the treatment period, it was measured 3 times daily for 2 weeks using an ion chamber(PTW-30013, PTW). The fourth experiment was compared the treatment plan and measured dose distributions using bolus, rice, colloid gel and additional, dose profiles in an environment similar to actual treatment using our own acrylic phantom. Result : First experiment, density of the colloid gel cases 1, 2 and 3 was $1.02g/cm^3$, $0.99g/cm^3$ and $0.96g/cm^3$. When the homogeneity was measured at 6 MV and 9 MeV, case 1 was more homogeneous than the other cases, as 1.55 and 1.98. In the second experiment, the HU values of case 1, 2, 3 were 15 and when the treatment plan was compared with the measured doses, the difference was within 1 % at all 9, 12 MeV and a difference of -1.53 % and -1.56 % within the whole 2 % at 6 MV. In the third experiment, the dose change of colloid gel was measured to be about 1 % for 2 weeks. In the fourth experiment, the dose difference between the treatment plan and EBT3 film was similar for both colloid gel and bolus, rice at 6 MV. But colloid gel showed less dose difference than bolus and rice at 9 MeV. Also, dose profile of colloid gel showed a more uniform dose distribution than the bolus and rice. Conclusion : In this study, the density of colloid gel prepared for radiation therapy was $1.02g/cm^3$ similar to the density of water, and alteration or deformation was not observed during the radiotherapy process. Although we pay attention to the density when manufacturing colloid gel, it is sufficient in that it can deliver the dose uniformly through the compensation of the patient's body surface more than the bolus and rice, and can be manufactured at low cost. Further studies and studies for clinical applications are expected to be applicable to radiation therapy.

• Progress in Medical Physics
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• v.23 no.1
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• pp.48-53
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• 2012

The pencil beam convolution (PBC) algorithms in radiation treatment planning system have been widely used to calculate the radiation dose. A new photon dose calculation algorithm, referred to as the anisotropic analytical algorithm (AAA), was released for use by the Varian medical system. The aim of this paper was to investigate the difference in dose calculation between the AAA and PBC algorithm using the intensity modulated radiation therapy (IMRT) plan for lung cancer cases that were inhomogeneous in the low density. We quantitatively analyzed the differences in dose using the eclipse planning system (Varian Medical System, Palo Alto, CA) and I'mRT matirxx (IBA, Schwarzenbruck, Germany) equipment to compare the gamma evaluation. 11 patients with lung cancer at various sites were used in this study. We also used the TLD-100 (LiF) to measure the differences in dose between the calculated dose and measured dose in the Alderson Rando phantom. The maximum, mean, minimum dose for the normal tissue did not change significantly. But the volume of the PTV covered by the 95% isodose curve was decreased by 6% in the lung due to the difference in the algorithms. The difference dose between the calculated dose by the PBC algorithms and AAA algorithms and the measured dose with TLD-100 (LiF) in the Alderson Rando phantom was -4.6% and -2.7% respectively. Based on the results of this study, the treatment plan calculated using the AAA algorithms is more accurate in lung sites with a low density when compared to the treatment plan calculated using the PBC algorithms.