• Korean Journal of Materials Research
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• v.9 no.9
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• pp.872-877
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• 1999

The purpose of this research was to investigate the characteristics and the cleaning efficiency on HN(sub)4OH solutions added with H(sub)2O(sub)2 and surfactants. NH(sub)4OH solutions added with surfactants did not show much changes in pH and redox potential (Eh) as a function of NH(sub)4OH concentration compared with NH(sub)4OH solution. However H(sub)2O(sub)2 added NH\ulcornerOH solutions showed the decrease of pH and the increase of Eh as the concentration of NH(sub)4OH increased. The decrease of surface tension from 72 dynes/cm to 38 dynes/cm was observed in solutions added with surfactant but not in H(sub)2O(sub)2. The etch rates of silicon in NH(sub)4OH solutions(NH(sub)4OH:H(sub)2O= 1 : 5) showed at least 50 times higher than those in H(sub)2O(sub)2 and surfactant added NH(sub)4OH solutions(NH(sub)4OH:H(sub)2O(sub)2= 1 : 1 : 5) solution removed the PSL particles (0.67$\mu\textrm{m}$ in diameter) on Si wafers effectively at all temperatures investigated. NH(sub)4OH solution added with a surfactant could not remove particles at room temperature, however it was possible to remove particles at higher temperatures, 5$0^{\circ}C$ and 8$0^{\circ}C$.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.198-207
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• 2012

In this study, we investigated the effect of ocean fertilization by deep sea water, using an ecosystem model which contains not only phytoplankton but also zooplankton. The model is based on NEMURO which consists of eleven compartments - two species of phytoplankton, three species of zooplankton, $NO_3$, $NH_4$, $Si(OH)_4$, particulate organic nitrogen, dissolved organic nitrogen and particulate silicon. We introduced nitrogen cell quota in the both species of phytoplankton, and silicon cell quota in the large phytoplankton in addition to the eleven compartments of NEMURO. We made the experiment at Izu Oshima Island in order to investigate the effect of ocean fertilization. In this experiment, we could not find clear differences between the cases with and without deep sea water. We investigated the causes of the experiment results by the model simulations. One of the causes was high concentrations of nutrients in surface seawater used in the experiment. Another was that the increase of total concentration of inorganic nitrogen does not necessarily accelerate the photosynthetic rate because inorganic nitrogen uptake rate is related to the ratio of $NO_3$ to $NH_4$. Because the model can represent the results of the experiment, we investigated the effect of ocean fertilization by deep sea water using this model. We found that the effect of ocean fertilization hardly appeared when the interval of the addition of deep sea water was too short, or the amount of deep sea water was too much. It is supposed that if the addition of deep sea water is too frequent or too much, the dilution of plankton's concentrations will exceed the effect of promoting phytoplankton's photosynthesis.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.255-260
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• 2003

Silicon is known to accumulate in plants and results in greater resistance to diseases and insect pests. In this study, we investigated the effect of silicate fertilizer applied in soil on the development of powdery mildew of oriental melon. Oriental melon seedlings of four-leaf stage were transplanted and grown in a plastic film house. Silicate fertilizer was applied to maintain soil available $SiO_2$ level of 200 mg/kg one week before transplanting. Fungicide triflumizol was sprayed three times; one, two, and three weeks after transplanting. Sphaerotheca fuliginea was inoculated 2 weeks after transplanting. The number of infected leaf and the number of fungal colony in leaves were measured one, two, and three weeks after the inoculation. Three weeks after the fungal inoculation, in the treatment of fungicide triflumizol. infected leaf numbers and number of colony per leaf were reduced by 10 and 58%, respectively. In the silicate fertilizer treatment, infected leaf numbers and numbers of colony per infected leaf were suppressed only by 6 and 16%, respectively, and the efficacy was lower than that of the fungicide triflumizol. The combined treatment of silicate fertilizer and the fungicide suppressed powdery mildew more effectively, and infected leaf numbers and numbers of colony per leaf were reduced by 31 and 80%, respectively. These results indicate that although silicate fertilizer itself is not much effective in the suppression of powdery mildew, it can significantly enhance the efficacy of the fungicide.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.283-290
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• 1999

The $n^+/p/p^+$ junction PERL solar cell of $0.1{\sim}2{\Omega}{\cdot}cm$ (100) p type silicon wafer was fabricated through the following steps; that is, wafer cutting, inverted pyramidally textured surfaces etching by KOH, phosphorus and boron diffusion, anti-reflection coating, grid formation and contact annealing. At this time, the optical characteristics of device surface and the efficiency of doping concentration for resistivity were investigated. And diffusion depth and doping concentration for n+ doping were simulated by silvaco program. Then their results were compared with measured results. Under the illumination of AM (air mass)1.5, $100\;mW/cm^2$ $I_{sc}$, $V_{oc}$, fill factor and the conversion efficiency were 43mA, 0.6 V, 0.62. and 16% respectively.

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.477-485
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• 2020

This study is a random allocation similar experimental study to compare and analyze the difference in BVM (Bag-Valve-Mask) ventilation volume according to the characteristics of the rescuer's hand and the type of mask using a standardized mannequin. To this end, the Basic Life Resuscitation Education Center of D University in gwangju. Recruiting 39 students who have completed the basic resuscitation course for emergency medical personnel and the Korean-style specialized cardiac rescue course, In addition to measuring the physical characteristics of the hand, the average amount of ventilation per minute using a bag-mask was measured and analyzed. As a result, the type of mask that was not most affected by the characteristics of the hand and provided adequate Minute Ventilation was the soft type (tube, silicone) mask. On the other hard (tube, silicone) masks were found to be unsuitable for general use as they were greatly affected by the characteristics of workers' hands. COVID-19 is currently increasing the risk of transmission to paramedics and patients. Considering this situation, the universal use of a semi-permanent hard-type mask, which is disadvantageous not only for preventing infection but also for proper ventilation, should be avoided. In addition to the ease of use, it should be actively utilized in the field by supplying a soft type mask that can provide stable ventilation even with 'predominance recognition' and proper ventilation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.7-11
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• 2022

Recently, Hanmi Gemological Institute & Laboratory (HGI) had an opportunity to examine 5 transparent synthetic moissanite. The round brilliants ranged from 0.93 to 0.96 ct and had a colorless, pink, yellow, blue, and red color. Advanced testing results, including Fourier-transform infrared (FTIR) and Raman spectroscopy, identified all the specimens as synthetic moissanite. Under the microscope, all samples except the colorless were confirmed to be a synthetic moissanite coated with a colored film. EDXRF chemical analysis detected very weak X-ray fluorescence peak characteristics of Ca, Ti, and Co in the colored samples. These features were not detected in the colorless sample. Raman spectroscopy investigation was unable to detect the 1332 cm^-1 (produced by sp³ bonding of carbon atoms) or the ~1550 cm^-1 (produced by graphite-related sp² bonding) peak in the colorless sample. The SEM image of the colorless sample showed no indication of a coating. The TEM image of the colorless sample revealed the presence of a 3~8 nm thick layer on the moissanite. Moreover, from the corresponding STEM Z-contrast image combined with the energy-dispersive X-ray spectroscopy (EDX) line profiles and EDX elemental maps, this layer was estimated to be carbon, silicon and oxygen.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.119-126
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• 2012

Portland cement production-1.5billion tonnes yearly worldwide-contributes substantially to global atmospheric pollution(7% of total of $CO_2$ emissions). Attempts to increase the utilization of fly ash, by-products from thermal power plant to partially replace the cement in concrete are gathering momentum. But most of fly ash is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. Instead, the sources of material such as fly ash, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effect reduction of $CO_2$ gas. In this study, we investigated the influence of the compressive strength of mortar on alkaline activator and curing condition in oder to develop cementless fly ash based alkali-activated concrete. In view of the results, we found out that it was possible for us to make alkali-activated mortar with 70MPa at the age of 28days by using alkaline activator manufactured as 1:1 the mass ratio of 9M NaOH and sodium silicate and applying the atmospheric curing after high temperature at $60^{\circ}C$ for 48hours.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.678-686
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• 2016

The effect of internal and shroud nozzle distributor to bubbling fluidized beds which has the size of $0.3m-ID{\times}2.4m-high$ column was modeled by CPFD (Computational Particle-Fluid Dynamics). Metal-grade silicon particles (MG-Si) were used as bed materials which have $d_p=149{\mu}m$, ${\rho}_p=2,325kg/m^3$ and $U_{mf}=0.02m/s$. Total bed inventory and static bed height were 75 kg and 0.8 m, respectively. Effect of vertical internal on the bubble rising velocity was investigated. Bubbles were split by internal when the axial position of the internal from the distributor, z = 0.45 m. Bed pressure drop and axial solid holdup were not affected by internal. However, in the case that axial distance of internal from distributor was too close to jet penetration length, bubbles were not separated and bypassed internal, and faster than without internal or z = 0.45 m.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.3
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• pp.47-52
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• 2008

This investigation was performed in order to study the properties of deposition and layers by Silicon Dioxide, SiO2, as dielectric onto Via and Trench which have high Aspect Ratio (AR). Thus, in order to confirm these properties, three types of CVD, which were PECVD, PETEOS, and ALD, were selected. On the experiment each of the property sections was estimated that step overage of PECVD: <30%, PETEOS: 45%, ALD: 75% and the RSM of PECVD: 27.8 nm, PETEOS: 2.1 nm, ALD: <2.0 nm. As a result of this experiment for the property of electric film, ALD was valuated to be the most favorable outcome. However, ALD was valuated to have the least quality for the deposition rate. ALD deposition rate, $10\;\AA/min$ by $1\;\AA$/1cycle, was prominently lower than PETEOS, which had the deposition rate of $5000\;\AA$/min. Since electric film requires at least $1000\;\AA$ thicknesses, ALD was not suitable for the deposition rate. which is the most important component in a practical use. Therefore, in this particular study, PETEOS was evaluated to be the most suitable recipe.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.475-480
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• 2017

In this paper, the conductivity of the fine pattern is improved in the insulating substrate by laser-induced forward transfer (LIFT) process. The high laser beam energy generated in conventional laser induced deposition processes induces problems such as low deposition density and oxidation of micro-patterns. These problems were improved by using a polymer coating layer for improved deposition accuracy and conductivity. Chromium and copper were used to deposit micro-patterns on silicon wafers. A multi-pulse laser beam was irradiated on a metal thin film to form a seed layer on an insulating substrate(SiO2) and electroless plating was applied on the seed layer to form a micro-pattern and structure. Irradiating the laser beam with multiple scanning method revealed that the energy of the laser beam improved the deposition density and the surface quality of the deposition layer and that the electric conductivity can be used as the microelectrode pattern. Measuring the resistivity after depositing the microelectrode by using the laser direct drawing method and electroless plating indicated that the resistivity of the microelectrode pattern was $6.4{\Omega}$, the resistance after plating was $2.6{\Omega}$, and the surface texture of the microelectrode pattern was uniformly deposited. Because the surface texture was uniform and densely deposited, the electrical conductivity was improved about three fold.