• Journal of the Optical Society of Korea
• /
• v.18 no.4
• /
• pp.307-316
• /
• 2014

Improved power conversion efficiency of hybrid solar cells with ITO/ZnO seed layer/ZnO NRs/ZnS QDs/P3HT/PCBM/Ag structure was obtained by optimizing the growth period of ZnO nanorods (NRs). ZnO NRs were grown using a hydrothermal method on ZnO seed layers, while ZnS quantum dots (QDs) (average thickness about 24 nm) were fabricated on the ZnO NRs by the successive ionic layer adsorption and reaction (SILAR) technique. Morphology, crystalline structure and optical absorption of layers were analyzed by a scanning electron microscope (SEM), X-ray diffraction (XRD) and UV-Visible absorption spectra, respectively. The XRD results implied that ZnS QDs were in the cubic phase (sphalerite). Other experimental results showed that the maximum power conversion efficiency of 4.09% was obtained for a device based on ZnO NR10 under an illumination of one Sun (AM 1.5G, $100mW/cm^2$).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1992.05a
• /
• pp.97-100
• /
• 1992

The Degradation mechanism of the ZnO-varistor fabricated with the content of a 3-Composition seed grain is discussed using the method of Thermally Stimulated Current (TSC). The spectra of TSC is measured in the temperature range of -130～270$^{\circ}C$ with a various forming electric fields E$\sub$f/, temperature T$\sub$f/ time tf, and a various rising rate of temperature. It is observed that there are appeared the peaks of ${\alpha}$, ${\alpha}$$_2$, ${\beta}$ and ${\gamma}$from high temperature in a TSC spectrum. It seems that ${\alpha}$$_1$ peak is due to thermal depolarization of donor ions forming the space charge in the depletion layer, and ${\alpha}$$_2$peak is due to the detrapping of trapped electrons in deep trap level of intergranular layer, and ${\beta}$ peak is due to the thermal exciting of carrier existing in the donor level of grain itself, and ${\gamma}$ peak is due to the thermal exciting of trapped carrier in all shallow trap site randomly distributed in the inner of sample and/or a intrinsic impurity existing in it.

• Journal of Sensor Science and Technology
• /
• v.19 no.3
• /
• pp.202-208
• /
• 2010

This study examined the dependency of crystalline orientation and electric properties of sol-gel PZT film on hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The PZT thin films were prepared by using 2-Methoxyethanol-based sol-gel method and spin-coating on Pt/Ti/$SiO_2$/Si substrates. The 1-${\mu}m$-thick PZT films were coated and then fired in a furnace by direct insert method. The highly (111) oriented PZT film of pure perovskite structure could be obtained. We could control the degree of orientation by various parameters such as hydrolysis, a $PbTiO_3$ seed layer and a concentration of sol-gel solution. The highest measured remanent polarization, dielectric constant and piezoelectric coefficient are $24.16\;{\mu}C/cm^2$, 2808, and 159 pC/N, respectively.

• Journal of Surface Science and Engineering
• /
• v.51 no.5
• /
• pp.263-270
• /
• 2018

Ag-coated Cu dendrites were prepared as a filler for an electromagnetic interference shielding application. Ag layers on the Cu dendrites was coated by two approaches. One is a direct autocatalytic plating with a reducing agent. The other approach was achieved by two-step plating, a galvanic displacement reaction to form Ag seed layers on Cu following by an autocatalytic plating with a reducing agent. The procedure-dependent average particle size and tap density of Ag-coated Cu dendrites were characterized. The electrical resistance and electromagnetic interference shielding effect (EMI SE) were analyzed with the Ag-coated Cu dendrites prepared in the two approaches. Additionally, the content of the Ag coated on Cu dendrites was controlled from 2% to 20%. The electrical resistance and EMI SE were critically determined by Ag contents coated on Cu.

• Journal of the Microelectronics and Packaging Society
• /
• v.29 no.4
• /
• pp.77-82
• /
• 2022

During etching process of PCB, the electroplated copper line and seed layer copper have different etching rates and it caused the over etching of copper line as well as undercut of lines. In this research, the effects of etchants composition on copper etching characteristics were investigated. The optimum concentration of hydrogen peroxide and sulfuric acid of etchants were obtained using polarization and OCV (open circuit voltage) analysis for both rolled copper and electroplated copper. The inhibiting effects of different inhibitors were investigated using OCV and ZRA (zero resistance ammeter) analysis. The galvanic current between electroplated copper and seed layer copper were measured using ZRA method. Inhibitors for least galvanic current could be chosen based on galvanic coupling in ZRA analysis.

• Membrane Journal
• /
• v.28 no.5
• /
• pp.340-350
• /
• 2018

In the present study, crystallographically b- and c-axis oriented mordenite zeolite membranes were prepared and their pervaporative ethanol dehydration was investigated. The seed layer with a high coverage grew to be c-axis oriented dense layer, while the seed layer with a low coverage grew to be b-axis oriented layer. This phenomenon could be explained by the evolutionary selection growth mechanism. The b-axis grown membrane with 8-membered rings showed a high separation factor of above 1000 and a considerable total flux of around $0.2kg/m^2h$. The c-axis grown, columnar structured membrane with 8- and 12-membered rings showed a low separation factor of less than 200 and a relatively high total flux of around $0.25kg/m^2h$. The high performance of b-axis grown membrane was due to the relatively small opening of 8-membered rings. Water molecules can freely permeate through the openings, but ethanol molecules, difficultly. Therefore, in the present study, we introduced a new method to control crystallographic orientation of mordenite membrane by changing seeding amount of needle-like crystals, and elucidated that b-axis oriented mordenite membrane showed better performance than c-axis grown mordenite membrane.

• Journal of Forest and Environmental Science
• /
• v.17 no.1
• /
• pp.1-17
• /
• 2001

Forming a part of "Cooperative Practical Study for the Modernization of the Management of National Forest", this study was conducted to provide overall ecological information for the natural regeneration of major tree species on the basis of community structural attributes in the deciduous forest ecosystem. Followings are summarized characteristics of the natural regeneration for the selected tree species. Betula costata : Although large number of seeds are dispersed by wind, they require mineral soils to germinate. Thick litter layer could be an obstacle to germinate. After germination, the seedling requires large amount of light for successful establishment. Acer mono : Characterized by high shade tolerance and weak drought resistance, the seedling should be overcasted with more than 50% of canopy coverage. High stand density should be maintained to produce good quality of timber. The potential of coppice may be high. Ulmus laciniata : Since this species needs high rate of troll moisture and light, around 60% of canopy coverage should be maintained to retain moisture and incoming light. The competition with other vegetation should be removed for the favor of successful seedling establishment. Fraxinus mandshurica : This species requires moist mineral soils to germinate. After germination, the seedling needs large amount of light and moisture for successful establishment. Site preparation should be applied to reduce competition with weedy vegetation. Fraxinus rhynchophylla : Interval of large seed crops may be highly varied. Thick litter layer could be an obstacle to germinate. Site preparation should be applied to reduce competition with weedy vegetation so as to achieve successful seedling establishment. Quercus mongolica : Including the difficulty of seed supply by the consumption, thick litter layer and mountain bamboo cover could be the obstacle to germinate. More than 50% of relative light intensity is necessary to achieve successful seedling establishment. Kalopanax pictus : Thick litter layer could be an obstacle to germinate. The seedling needs large amount of light and moisture for successful establishment. Abies holophylla : In spite of high shade tolerance, the growth rate in sapling stage may be extremely slow. Cornus controversa : Seeds (drups) are consumed and dispersed by animals, tending to be not sufficient in seed supply. This species requires large amount of light for successful germination and seedling establishment. Tilia amurensis : The difficulty of seed supply might be expected with low seed purity and double dormancy. Since thick litter layer could be an obstacle to germinate, the species requires moist mineral soils for successful germination. The potential of coppice may be extremely high.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.33 no.2
• /
• pp.112-121
• /
• 1988

Soybean seed coat consisted of three layers, and the aleurone layer was attached to the innermost part of seed coat. It showed the different morphological characteristics with single cell layer compared with many cell layers in barley aleurone layer. The structural difference in aleurone cell among varieties was not detected in this experiment. The hole of middle part of hilum consisted of net formed material in order to pass water and gas. In the experiment, it was not studied whether the varieties with hard seed consist of the same structure or not, but the detailed study on this would be necessary. The activity of acid phosphatase showed a tendency to increase in process of imbibition in distilled water. There was no significant difference in the enzyme activity among the varieties tested, but the enzyme activity of Danyoupkong was slightly higher than that of Hwanggeumkong. In germinability, Danyoupkong is higher than Hwangkeumkong, so it might be attributed to the higher activity. There was no difference in acid phosphatase activity between released from the aleurone cell and accumulated in the aleurone cell from 6 to 12 hours incubation of the medium in the absence of GA$_3$, but the difference was detected after 12 hours incubation. And enzyme activity was the highest in the 18 hours incubation. The increase in the release of acid phosphatase from the aleurone cell would be considered as passive diffusive effect due to the increase in turgo pressure of aleurone cell. The acid phosphatase released from aleurone layer increased greatly after 24 hours incubation of the medium in the presence of GA$_3$ and the accumulation within the aleurone cell decreased linearly after 18 hours incubation. The result indicates that GA$_3$ enhance the rate of enzyme release from aleurone layer, suggests that the aleurone cell wall be digested by the introduction of GA and the digested wall act as the channels for enzyme release.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.261-262
• /
• 2006

High temperature superconducting coated conductor has multi-layer structure of protecting layer/superconducting layer/buffer layer/metallic substrate. The buffer layer consists of multi layer, and the architecture most widely used in RABiTS approach is $CeO_2$(cap layer)/YSZ(diffusion barrier layer)/$CeO_2$(seed layer). Multi-buffer layer deposition required many times and process. Therefore single buffer layer deposition study reduce 2G HTS manufacture efforts. Evaporation technique for single buffer deposition method is used for the $CeO_2$ layer. $CeO_2$ single buffer film could be achieved in the chamber. Detailed deposition conditions (temperature and partial gas pressure of deposition) were investigated for the rapid growth of high quality $CeO_2$ single buffer film.

• Korean Journal of Medicinal Crop Science
• /
• v.26 no.1
• /
• pp.55-63
• /
• 2018

Background: The present study assessed the response of kenaf (Hibiscus cannabinus L., Jangdae) seed to NaCl and the effects of polyethylene glycol (PEG) on kenaf seed germination and vigor. Methods and Results: Seed germination ranged from 11.3% to 58.8% after 24 hours of immersion in NaCl concentrations from 0% to 0.5%. The priming treatments had lower electrical conductivity (EC) values for the seeds than for the control and a deteriorated palisade layer. Priming in 10% PEG for 48 hours increased the germination upto 96.3% in $H_2O$ solution and 98.8% in 0.3% NaCl solution compared to that of the control (78.8%). Germination synchronization, and shoot and root growth of the primed seeds were greater than those of the control. The $T_{50}$ of the control in $H_2O$ and 0.3% NaCl solution was 22 and 28 times, respectively. After priming, nine times was sufficient to reach $T_{50}$ in both solution. The mean number of days to germination (MDG) decreased from 1.43 days for the control to 0.55 days for 0% PEG in $H_2O$ solution and from 1.57 days for the control to 0.56 days for 0% PEG in 0.3% NaCl solution. The dry weight after the 10% PEG treatment was higher than that of the control. Conclusions: Taken together, 10% PEG treatment for 24 hours is recommended for kenaf seed invigoration before planting.