• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.380-383
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• 2015

We prepared the $TiO_2$ layer with 0 ~ 4 wt% of polystyrene (PS) beads having a radius of 250 nm to increase the dye adsorption and energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC). Then, we fabricated DSSCs using $0.45cm^2$ active area. FE-SEM was used to characterize the microstructure consisting of $TiO_2$ layer and PS beads. UV-VIS-NIR was used to determine the optical absorbance of working electrodes (WEs). Solar simulator and potentiostat were used to determine the photovoltaic properties. We observed that pores having a radius of 250 nm were formed with the density of $0.15ea/{\mu}m^2$ in $TiO_2$ layers after conducting the sintering process. The absorbance in visible light regime was found to increase with the increase in the amount of PS beads. The ECE increased from 4.66% to 5.25% when the amount of PS beads was increased from 0 to 4 wt%. This is because the pores of PS beads increased the adsorption of dye. Our results indicate that the ECE of the DSSCs can be enhanced by the addition of an appropriate amount of PS beads into $TiO_2$ layers.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.125-131
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• 1996

In this paper, we introduced the BQBPH method for making the grating of high efficiency which was improtant in implementing optical PS. The pattern of graing was obtianed by computer simulations using iterative method, and the diffraction efficeincy of designed grating was about 67% through BPM simulation. The grating was fabricated by laser beam writer, and the diffraction efficiency BPM simulation. The grating was fabricated by laser beam writer, and the diffraction efficiency was 47%. We implemented the optical PS with the grating and showed that optical experimental output patterns were good agreement with PS output patterns and first order was main diffraction order.

• Journal of Environmental Science International
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• v.6 no.4
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• pp.369-378
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• 1997

The effects of various intensity of W-B on barley seeding were investigated by PS I and II activities and chlorophyll fluorescence. The Inhibitory effect of UV-B radiation on electron transport activity was Increased as the intensity of UV-B Irradiation was increased. Especially, PS I is more sensitive to UV-B radiation than PS I is. By the addition of uncle electron donor, DPC, to the chloroplasts of the barley seedlings treated with UV-B, the photoreduction of DCPIP was recovered by only 1 IBI on electron transport activity. However, the activity of PS II was Inhibited by 45% by the treatment with UV-B, but recovered it only 11% by the addition of DPC. These suggest that other sites besides the oxidation site of PS II may be affected more by UV-B Irradiation. As the intensify of UV-B was Increased, Fo was Increased while Fv was decreased, and thus Fv/Fm was decreased. This means that photochemical efficiency was reduced. With this parameters, it might be that UV-B radiation affected adversely to around PS II.

• Asian Journal of Turfgrass Science
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• v.11 no.1
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• pp.45-58
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• 1997

Pigments and thylakoid membrane proteins were investigated in wild type and PS I- mutants from Synechocystis sp. PCC6803 Comparing morphological features, B2 was less fluorescent than the other strains. The contents of chlorophyll a were propotional to the FNR activity in thylakoid membrane. The FNR activity of mutants was lower than that of wild type. In the result of pigments analysis, mutants had smaller cholophyll a than that of wild type. The major carotenoid was found to he $\beta$-caroene, but aeaxanthin was barely detected in thylakoid membrane of mutants. The polypeptide, 14.8kD was detected by electrophoresis in mutants. It was considered to be the modification of 15.4kD in wild type. Membrane polypeptides of 17.6 and 19.7kD were not detected in mutants. In the result of western blotting, subunit I was detected in all strains, but subunit II was barely detected in mutants. Subunit II was not detected in B2 at all. In view of the results so far achieved, the changes of contents of chlorophyll and zeaxanthin were affected by the defficiency or modification of functional domain in subunit I. Also the modification in subunit I affected the subunit II- binding site in PS I. As the result, efficiency of photosynthesis was decreased. Key words: Synechoystis sp. PCC6803, PS I - mutant, Photosynthetic efficiency, Pigment,Thylakoid membrane proteins, Subunit I, II.

• Journal of Soil and Groundwater Environment
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• v.26 no.1
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• pp.45-53
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• 2021

The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution by coupled electro-oxidation and Fe(II) activated persulfate oxidation process was investigated. The electrochemical oxidation was performed using carbon sheet electrode and persulfate using Fe(II) ion as an activator. The oxidation efficiency was investigated by varying current density (2 - 10 mA/㎠), electrolyte (Na2SO4) concentration (10 - 100 mM), persulfate concentration (5 - 20 mM), and Fe(II) concentration (10 - 20 mM). The 2,4-D removal efficiency was in the order of Fe(II) activated persulfate-assisted electrochemical oxidation (Fe(II)/PS/ECO, 91%) > persulfate-electrochemical oxidation (PS/ECO, 51%) > electro-oxidation (EO, 36%). The persulfate can be activated by electron transfer in PS/ECO system, however, the addition of Fe(II) as an activator enhanced 2,4-D degradation in the Fe(II)/PS/ECO system. The 2,4-D removal efficiency was not affected by the initial pHs (3 - 9). The presence of anions (Cl- and HCO3-) inhibited the 2,4-D removal in Fe(II)/PS/ECO system due to scavenging of sulfate radical. Scavenger experiment using tert-butyl alcohol (TBA) and methanol (MeOH) confirmed that although both sulfate (SO4•-) and hydroxyl (•OH) radicals existed in Fe(II)/PS/ECO system, hydroxyl radical (SO4•-) was the predominant radical.

• Korean Journal of Organic Agriculture
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• v.4 no.1
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• pp.13-28
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• 1995

This study analyzed marketing activities of producers' organization on organic farming products(O.F.Ps), and was inquired into direction of consumption increase by it. As a result, in order to raise marketing efficiency and to increase consumption of O.F.Ps, the present questions and issues which are to be solved is as follows: Consumer's confidence for O.F.Ps should be obtained broadly and formally. Particulary, the use of brand such as 'no pollution' or ' no pesticides' should be forbidden without institutional certification. Thus cosumers should be able to distinguish O.F.Ps from general farming products(G.F.Ps) by the brand. Also physical marketing is inefficient since many items are marketed in small amount, and marketing cost is spendedtoo much relatively. Physical marketing center to cut down this expenses should be constructed under government support largely. And the consumers' price of O.F.Ps tends to be fixed all the year round. Owing to this feature, the consumers' price of G.F.Ps have severely influece upon at once demand and supply of O.F.Ps. The associations of consumer and producer should allow O.F.Ps price to fluctuate in proportion to G.F.Ps price. Besides, both should vary marketing patterns. Finally, government should help both associations legally and institutionally to improve all economic activities.

• Transactions on Electrical and Electronic Materials
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• v.5 no.5
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• pp.194-198
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• 2004

The influences of the deep-level concentration of p-type Si substrates on the optical properties of nano-porous silicon (PS) are investigated by deep level transient spectroscopy (DLTS) and photoluminescence (PL). Utilizing a Si substrate with Fe contaminations significantly enhanced the PL intensity of PS. All the PS samples formed on Fe-contaminated silicon substrates had stronger PL yield than that of reference PS without any intentional Fe contamination but the emission peak is not significantly changed. For the PS 1000 sample with Fe contamination of 1,000 ppb, the maximum PL intensity showed about ten times stronger PL than that of the reference PS sample. From PL and DLTS results, the PL efficiency strongly depends on the Fe-related trap concentration in Si substrates.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.610-615
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• 2010

This study was conducted to evaluate fertigation effects of pig slurry (PS) and chemical fertilizer (CF) in tomato by analyzing the growth and yield, nutrient content and uptake, nutrient use efficiency, and soil characteristics in greenhouse cultivation. The treatments compared were; no-fertilizer, two different levels of PS (26 mg $L^{-1}$ and 52 mg $L^{-1}$), and a control treatment of chemical fertilizer. There was no significant difference in growth and yield between PS and CF treatments. however, yield reduction was observed in PS 26 mg $L^{-1}$ treatment. The N-utilization efficiency in CF treatment was similar to that of PS 52 mg $L^{-1}$ treatment. Nutrient utilization efficiency decreased in order of potassium (K), nitrogen (N), phosphate (P) with 29.2~43.3% in K, 15.8~36.7% in N, and 3.0~6.3% in P. In soil chemical characteristics, soil pH in PS treatment was higher than in CF treatment. In contrast, nitrate content in soil was higher in CF treatment than in PS treatment. The content of exchangeable K in soil was higher in PS and CF 52 mg $L^{-1}$ treatments. There was no significant difference in exchangeable Ca and Mg among those treatments. Therefore, it can be concluded that chemical fertilizers can be substituted by PS based on soil chemical analysis in tomato fertigation culture.

• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.43-51
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• 2012

Rreactivity of persulfate (PS) for oxidation of TCE under various conditions such as heat, $Fe^{2+}$, and UV was investigated. It was found that degradation rate of TCE increased with increasing temperature from 15 to $35^{\circ}C$. At pH 7.0, the rate constants (k) at 15, 25, 30, and $35^{\circ}C$ were 0.07, 0.30, 0.74, and $1.30h^{-1}$, respectively. For activation by $Fe^{2+}$, removal efficiency of TCE increased with increasing $Fe^{2+}$ concentration from 1.9 mM to 11 mM. The maximum removal efficiency of TCE was approximately 85% when pH of the solution dropped from 7.0 to 2.5. Degradation of TCE by UV-activated PS was the most effective, showing that the degradation rate of TCE increased with inreasing PS dosage; the rate constants (k) at 0.5, 2.5, and 10 mM were 34.2, 40.5, and $55.9h^{-1}$, respectively. Our results suggest that PS activation by UV/PS process could be the most effective in activation processes tested for TCE degradation. For oxidation process by PS, however, pH should be observed and adjusted to neutral conditions (i.e., 5.8-8.5) if necessary.

• Biomaterials Research
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• v.22 no.4
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• pp.303-310
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• 2018

Background: Photodynamic therapy (PDT) is photo-treatment of malignant or benign diseases using photosensitizing agents, light, and oxygen which generates cytotoxic reactive oxygens and induces tumour regressions. Several photodynamic treatments have been extensively studied and the photosensitizers (PS) are key to their biological efficacy, while laser and oxygen allow to appropriate and flexible delivery for treatment of diseases. Introduction: In presence of oxygen and the specific light triggering, PS is activated from its ground state into an excited singlet state, generates reactive oxygen species (ROS) and induces apoptosis of cancer tissues. Those PS can be divided by its specific efficiency of ROS generation, absorption wavelength and chemical structure. Main body: Up to dates, several PS were approved for clinical applications or under clinical trials. $Photofrin^{(R)}$ is the first clinically approved photosensitizer for the treatment of cancer. The second generation of PS, Porfimer sodium ($Photofrin^{(R)}$), Temoporfin ($Foscan^{(R)}$), Motexafin lutetium, Palladium bacteriopheophorbide, $Purlytin^{(R)}$, Verteporfin ($Visudyne{(R)}$), Talaporfin ($Laserphyrin^{(R)}$) are clinically approved or under-clinical trials. Now, third generation of PS, which can dramatically improve cancer-targeting efficiency by chemical modification, nano-delivery system or antibody conjugation, are extensively studied for clinical development. Conclusion: Here, we discuss up-to-date information on FDA-approved photodynamic agents, the clinical benefits of these agents. However, PDT is still dearth for the treatment of diseases in specifically deep tissue cancer. Next generation PS will be addressed in the future for PDT. We also provide clinical unmet need for the design of new photosensitizers.