• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.787-790
• /
• 2003

A rf triode magnetron sputtering system is designed and installed its construction in vacuum chamber. In order to calibrate the rf triode magnetron sputtering for thin films deposition processes, the effects of different glow discharge conditions were investigated in terms of the deposition rate measurements. The basic parameters for calibrating experiment in this sputtering system are rf power input, gas pressure, plasma current, and target-to-substrate distance. Because a knowledge of the deposition rate is necessary to control film thickness and to evaluate optimal conditions which are an important consideration in preparing better thin films, the deposition rates of copper as a testing material under the various sputtering conditions are investigated. Furthermore, a triode sputtering system designed in our team is simulated by the SIMION program. As a result, it is sure that the simulation of electron trajectories in the sputtering system is confined directly above the target surface by the force of $E{\times}B$ field. Finally, some teats with the above 4 different sputtering conditions demonstrate that the deposition rate of rf triode magnetron sputtering is relatively higher than that of the conventional sputtering system. This means that the higher deposition rate is probably caused by a high ion density in the triode and magnetron system. The erosion area of target surface bombarded by Ar ion is sputtered widely on the whole target except on both magnet sides. Therefore, the designed rf triode magnetron sputtering is a powerful deposition system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.960-964
• /
• 2004

[ $Ba_2NaNb_5O_{15}$ ](BNN) thin films have been prepared by the ion beam sputter deposition (IBSD) method on Pt coated Si substrate at temperature as low as $600^{\circ}C$ XRD, SEM were used to investigate the crystallization and microstructure of the films. It was found that the films were crack-free and uniform in microstructure. The electric properties of thin films were carried out by observation of D-E hysteresis loop, dielectric constant and leakage current. It was found the deposition rate strongly influenced the phase formation of the films, where the phase of $BaNb_2O_6$ was always formed when the deposition rate was high. However, the single phase (tungsten bronze structure ) BNN thin film was obtained with the deposition rate as low as $22{\AA}/min$. The remanent polarization Pr and dielectric constant are about 1-2 ${\mu}C/cm^2$ and $100\sim200$, respectively. It was also founded the electric properties of thin films were influenced by the deposition rate. The Pr and dielectric constant of films increased with the decrease of deposition rate. The effects of annealing temperature and annealing time to the crystallization behavior of films were studied. The crystallization of thin film started at about $600^{\circ}C$. The adequate crystallization was gotten at the temperature of $650^{\circ}C$ when the annealing time is 0.5 hour or at the temperature of $600^{\circ}C$ when the annealing time is long as 6 hours.

• Journal of Environmental Science International
• /
• v.20 no.4
• /
• pp.457-463
• /
• 2011

This study was carried out to compare the toxicity of nano and micrometer particles with Cu and Zn on soil microbial community and metal uptake of buck wheat. In microcosm system, soil was incubated for 14 days after soil aliquots were artificially contaminated with 1,000 mg/kg Cu, Zn nano and micro particles, respectively. After then, buck wheat was planted in incubating soils and non incubating soils. After 14 days, we compared bioaccumulation of metal, and microbial carbon substrate utilization patterns between incubating soils and non-incubating soils. The enrichment factor (EF) values of incubating samples were greater than non-incubating soils. Dehydrogenase activity had been inhibited by Cu and Zn nanoparticles in non-incubating soil, as well as it had been inhibited by Zn micro particles in incubating soils. Results of biolog test, it was not significant different between nano particles and micro particles. It cannot be generalized that nanoparticles of metal are always more toxic to soil microbial activity and diversity than micrometer-sized particles and the toxicity needs to be assessed on a case-by-case basis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.7
• /
• pp.705-711
• /
• 2003

In this Paper, 2${\times}$100 $\mu\textrm{m}$ AlCaN/GaN HEMT's(on sapphire substrate) large signal model including thermal effect was extracted. An equation based empirical model was employed to make large signal model for convergence and high speed. Pulsed I-V measurement was performed to extract thermal resistance and capacitance. Power amplifiers with 9 mm and 15 mm AlCaN/GaN HEMTS were designed using scaled modeling results of 2${\times}$100 $\mu\textrm{m}$ device respectively. From comparisons between measured and simulated data, the model considering of thermal effects gave better agreement than without one. It demonstrates that thermal modeling must be performed for power amplifier that uses large size transistors.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.9
• /
• pp.919-929
• /
• 2014

In recent, the requirements for the safety to the effects of high power electromagnetic wave have been increased along with the development of electricity and electronic equipments. The small sized electronic devices and the various components have been analyzed by using the full-EM simulation and solving a complete set of Maxwell equation. However, the deterministic approach has a drawback and much limitation in the electromagnetic analysis of an electrically large cavity with a high complexity of the structure. In this paper, statistical theory and topological modeling method are combined to analyze the large cavity with a complex structure. In particular, the PWB(Power Balance) method and BLT(Baum-Liu-Tesche) equation are combined and employed to solve the frequency response to the large-scaled cavity with remarkably reduced time-consumption. For instance, a PCB substrate inside box of box are considered as a large structure with a complexity.

• Journal of Bio-Environment Control
• /
• v.15 no.4
• /
• pp.322-326
• /
• 2006

This experiment has investigated the effects of silicon on albinism of strawberry. Albino fruit appeared after a month of treatment of potasium silicate(Si) in nutrient solution. When $200mL{\cdot}L^{-1}$ of Si applied, number of albino fruit increased over 90% of total amount of fruit, and the symptom remained latest any other treatment. The fruit length of the strawberries in Si treatments were longer than control treatment. However, the diameter and weight of fruit decreased in treatment of Si. The soluble solids of fruits, numbers of fruit and yield per plant were no significant differences among treatments. The rate of albino fruit was significantly increased with increase of concentration of Si. The results of this experiment will be utilized for the cultivation in the new substrate application for strawberry hydroponics.

• ALGAE
• /
• v.32 no.4
• /
• pp.325-336
• /
• 2017

Intertidal community recovery and resilience were investigated with quantitative and qualitative perspectives as a function of disturbance timing. The study was conducted in a lower intertidal rock bed of the southern coast of South Korea. Six replicates of artificial disturbance of a $50cm{\times}50cm$ area were made by clearing all visible organisms on the rocky substrate in four seasons. Each of the seasonally cleared plots was monitored until the percent cover data reached the control plot level. There was a significant difference among disturbance timing during the recovery process in terms of speed and community components. After disturbances occurred, Ulva pertusa selectively preoccupied empty spaces quickly (in 2-4 months) and strongly (50-90%) in all plots except for the summer plots where non-Ulva species dominated throughout the recovery period. U. pertusa acted as a very important biological variable that determined the quantitative and qualitative recovery capability of a community. The qualitative recovery of communities was rapid in summer plots where U. pertusa did not recruit and the community recovery rate was the lowest in winter plots where U. pertusa was highly recruited with a long duration of distribution. In this study, U. pertusa was a pioneer species while being a dominant species and acted as a clearly negative element in the process of qualitative recovery after disturbance. However, the negative effect of U. pertusa did not occur in summer plots, indicating that disturbance timing should be considered as a parameter in understanding intertidal community resilience in temperate regions with four distinct seasons.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.2
• /
• pp.117-123
• /
• 2012

This paper discusses two different techniques used to measure the mechanical properties of thin films: the bulge test and the nanoindentation test. In the bulge test, a uniform pressure is applied to one side of the film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties such as Young's modulus, and the residual stress. A nanoindentation test is performed by pushing an indenter tip into the specimen and then withdrawing it, and then recording the indentation force as a function of the indenter position. A modified King's model is used to estimate the mechanical properties of the thin film in order to avoid the effects of the substrate layers. A combination of both the bulge test and the nanoindentation test can determine both Young's modulus and Poisson's ratio simultaneously.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.17 no.3
• /
• pp.751-758
• /
• 2003

In our previous studies, we reported that Selaginella Tamariscina(ST) induced apoptotic cell death in HL-60 cells selectively. The cell viability after treatment with extract of ST was quantified by MTT assay and trypan bleu exclusion method. The results showed that application with ST in HL-60 induced 40% cell death at the concentration of 400 ㎍/ml. The cancericidic effect of Selaginella Tamariscina was mediated by apoptosis. Thus, HL-60 cells exposed to Selaginella Tamariscina displayed the DNA fragmentation ladder and nucleus chromatin condensation characteristic for apoptosis. The enzyme activity of caspase-3 and actived caspase-3 protein were markedly increased in HL-60 cells treated with the extract of Selaginella Tamariscina. In addition, the extract of Selaginella Tamariscina induced cleavage of PARP, a known substrate for caspase-3. The expression of Bcl-2, anti-apoptotic protein, was decreased by treatment of the aqueous extract of Selaginella Tamariscina in a dose-dependent manner. And the expression of pro-apoptotic Bax protein was increased. In conclusion, our results suggest that the extract of Selaginella Tamariscina may induce the apoptotic death of HL-60 cells via activation of caspase-3, cleavage of PARP protein, depletion of cellular ATP levels and Bcl-2 degradation.

• Molecular & Cellular Toxicology
• /
• v.3 no.1
• /
• pp.36-45
• /
• 2007

Several features of the implant surface, such as topography, roughness, and composition play a relevant role in implant integration with bone. This study was conducted in order to determine the effects of different-coatings on Ti surfaces on the biological responses of a human osteoblast-like cell line (MG63). MG63 cells were cultured on HA (Hydroxyapatite coating on Titanium), Ano (HA coating on anodized surface Titanium), Zr (zirconium-coating on Titanium), and control (non-coating on Titanium). The morphology of these cells was assessed by SEM. The cDNAs prepared from the total RNAs of the MG63 were hybridized into a human cDNA microarray (1,152 elements). The appearances of the surfaces observed by SEM were different on each of the three dental substrate types. MG63 cells cultured on HA, Ano, Zr, and control exhibited cell-matrix interactions. In the expression of several genes were up-, and down-regulated on the different surfaces. The attachment and expression of key osteogenic regulatory genes were enhanced by the surface morphology of the dental materials used.