• Restorative Dentistry and Endodontics
• /
• v.39 no.4
• /
• pp.276-281
• /
• 2014

Objectives: The purpose of this study was to compare the cutting efficiency of a newly developed microprojection tip and a diamond-coated tip under two different engine powers. Materials and Methods: The apical 3 mm of each root was resected, and root-end preparation was performed with upward and downward pressure using one of the ultrasonic tips, KIS-1D (Obtura Spartan) or JT-5B (B&L Biotech Ltd.). The ultrasonic engine was set to power-1 or -4. Forty teeth were randomly divided into four groups: K1 (KIS-1D / Power-1), J1 (JT-5B / Power-1), K4 (KIS-1D / Power-4), and J4 (JT-5B / Power-4). The total time required for root-end preparation was recorded. All teeth were resected and the apical parts were evaluated for the number and length of cracks using a confocal scanning micrscope. The size of the root-end cavity and the width of the remaining dentin were recorded. The data were statistically analyzed using two-way analysis of variance and a Mann-Whitney test. Results: There was no significant difference in the time required between the instrument groups, but the power-4 groups showed reduced preparation time for both instrument groups (p < 0.05). The K4 and J4 groups with a power-4 showed a significantly higher crack formation and a longer crack irrespective of the instruments. There was no significant difference in the remaining dentin thickness or any of the parameters after preparation. Conclusions: Ultrasonic tips with microprojections would be an option to substitute for the conventional ultrasonic tips with a diamond coating with the same clinical efficiency.

• Membrane Journal
• /
• v.31 no.5
• /
• pp.363-370
• /
• 2021

Organic solvent resistant hollow fiber membranes were fabricated via a thermally induced phase separation (TIPS) method using Polyketone polymer, a material with excellent resistance to organic solvents. The PEG300, DMSO₂ and Glycerine called the "green solvents" were used as diluents for TIPS method. The spherulite structure was formed with DMSO₂ by S-L phase separation behavior whereas the bicontinuous structures were formed with PEG300 and Glycerine, respectively. The morphology of the PK hollow fiber membranes was investigated using SEM. The pure water permeability and the durability test were conducted to understand the permeation properties of PK hollow fiber membranes. The tensile strength test was conducted for the property of mechanical strength. In this study, the fabrication of PK hollow fiber membranes with various diluents was discussed to understand the correlation between diluent and polymer in detail.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.5
• /
• pp.871-876
• /
• 2019

We fabricated concave optical fiber tips using hydrofluoric acid solution and photothermal effect induced by $1.55{\mu}m$ wavelength laser applied to an optical fiber. The radius of curvature of the concave optical fiber tips fabricated with different applied laser power, etching time, and concentration of hydrofluoric acid was measured with an optical microscope. Then, we analyzed how the radius of curvature changes for those three variables. In addition, the reliability of the measurement method using a microscope was verified through a free spectral range(FSR) and a scanning electron microscope(SEM). Through this paper, the radius of curvature can be adjusted by the variables of the fabrication process of concave optical fiber tips; thus, it is overcoming the limitations of conventional optical fiber etching methods using hydrofluoric acid solutions.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2021.04a
• /
• pp.36-36
• /
• 2021

Cryopreservation has been broadly used as an efficient method for a long-term conservation for many types of plants especially vegetatively propagated plants. Among several cryopreservation methods, a droplet-vitrification was the most widely applicable and efficient method. Studies have developed protocols for strawberry using droplet-vitrification method and suggested the practical use of the protocol for large number of germplasm with a little modification. In this study, the droplet vitrification method of shoot tip has been tested on 31 accessions provided around the world. Shoot tips were precultured on Murashige and Skoog (MS) liquid medium supplemented with 0.3~0.5M sucrose. Precultured explants were osmoprotected with loading solution, 35% of PVS3 (C4, 17.5% glycerol and 17.5% sucrose) for 40 min and exposed to dehydration solution, PVS3 (B1, 50% glycerol and 50% sucrose) for 60 min. Then, the explants were transferred onto droplets containing 2.5 uL PVS3 on sterilized aluminum foils prior to direct immersion in liquid nitrogen (LN) for 1hr. The cryopreserved shoot tips were rapidly warmed in a water bath at 40C and then unloaded in MS with 0.8M sucrose for 40 min. The shoot tips were cultured in NH₄NO₃-free MS post culture medium for 2 weeks. Subsequently, the explants were moved to the MS medium for 6 weeks and evaluated the regrowth rate. By this droplet-vitrification protocol, twenty-four accessions showed at least 40% regrowth rate. Out of 24 accessions, 'Nonsan1ho' had the highest regeneration rate of 85.8% and 'Jumbo pureberry' had the lowest with 42.1%.

• Korean Journal of Agricultural Science
• /
• v.38 no.2
• /
• pp.227-233
• /
• 2011

This study aimed at developing cryopreservation protocol for chrysanthemum (Dendranthema grandiflora Tzelevcv. peak) shoot apices based on droplet-vitrification procedure, which is a combination of droplet-freezing and solution based vitrification. Progressive preculture of shoot apices in liquid MS medium supplemented with 0.3 and 0.7 M sucrose for 31 and 17 hours, respectively, was found optimum among preculture treatments tested. The composition of both loading and vitrification solutions significantly affected recovery growth of shoot tips before and after cryopreservation. Balancing glycerol and sucrose concentrations in the solutions was beneficial for recovery growth. The highest recovery after cryopreservation was observed when apical shoot tips were extracted from 4-week-old in vitro plantlets, progressively precultured with 0.3-0.5-0.7 M sucrose for 32-16-6 hours, respectively, then treated with loading solution comprising of 1.9 M glycerol + 0.5 M sucrose (35% PVS3 solution). Apices were then dehydrated with the vitrification solution consisted of 50% glycerol + 50% sucrose for 90 minutes then directly immersed in liquid nitrogen.

• Journal of the Korea Society of Computer and Information
• /
• v.9 no.3
• /
• pp.143-148
• /
• 2004

It is important the initial process during game development - the stage where creative idea expression is needed - decides the chance of success. CGTS(Creative Group Thinking System) is a web based system made for that particular-conceptual-step. As for this study is to show the conversion of ideas and the synergy effects of the tips given. Based on the facts, conceptual needs will be more strengthen during the initial stage. The intention of this study is to improve the game developing process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1228-1231
• /
• 2005

This paper reports about the development of scanning probe microscopy (SPM) tip with multi-walled carbon nanotube (MWNT). For making a carbon nanotube (CNT) modified tips, AC electric field which causes the dielectrophoresis was used for alignment and deposition of CNTs to the metal coated SPM tip. By dropping the MWNT solution and applying an electric field between an SPM tip and an electrode, MWNTs which were dispersed into a diluted solution were directly assembled onto the apex of the SPM tips due to the attraction by the dielectrophoretic force. In this paper, we investigate experimental conditions about the alignment of the CNT to tip axis according to the change of the angle between a tip and an electrode. Experimental results are presented, and then fabricated CNT tips are showed and measurement results for 15nm gold particles are compared with that of the conventional silicon tip.

• Asian Journal of Innovation and Policy
• /
• v.8 no.3
• /
• pp.396-416
• /
• 2019

The key conditions for the promotion of innovative technology-based start-ups are expanding the market for innovative technology products and services, increasing equity-based funding opportunities, promoting the commercialization of technological innovation, and establishing a fair-trade system for start-ups to compete fairly in the market. Besides, there is a need for a support system that minimizes the cost of failure in case of business failure to facilitate re-challenge and provides education and training opportunities to enhance entrepreneurial capabilities. To activate technology-based start-ups, the Korean government introduced the TIPS policy in 2013. It is a program that creates technology start-up with private investment led by successful venture entrepreneurs, which has shown remarkable achievement and is regarded as the most successful policy in this field up to now. The most critical factor contributed to the success of this program is to invite private investors to select a technology entrepreneurship team and provide mentoring with the investment. The government provides R&D funding with matching investment, commercialization and marketing support to ensure that technology start-ups survive crossing the death-valley. Subsequent investments from domestic and abroad investors are actively made and it is becoming a representative technology-based start-up program in Korea.

• Mycobiology
• /
• v.31 no.1
• /
• pp.23-31
• /
• 2003

With universal primer ITS1-F, the specific DHJ2 primer was developed to detect the Ectomycorrhizal(ECM) root tips in soil and to identify the species of ECM fungi, as based on DNA sequences of rDNA stored in GeneBank of NCBI. This primer was designed with the common sites of rDNA of Amanita and Boletus, and was also designed with several DNA programs provided by NCBI. The DNA fragments synthesized by PCR were calculated to be 1,000 to 1,200 bps of DNA located to 18s to 28s rDNA to contain two variable sites of ITS, indicating much diversities for specific species or ecotypes of ECM fungi. The primer DHJ2 reacted with the genomic DNA's extracted from the tissues of basidiocarp at the rate of 73 of 80 fungi collected produced single bands with a 1,100 bps length. The DNA fragment synthesized with the genomic DNA that extracted from eight ECM tips of Pinus densiflora was confirmed and analysized to the rDNAs of ECM in full sequences, and informed to be a ECM fungal species in the forest.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.5
• /
• pp.2019-2024
• /
• 2011

The effect of the wear of contact tips on the weld beads made by a Gas Metal Arc Welding(GMAW) process was studied. In order to correlate between the wear of tips and beads, the droplet transfer was investigated by a high speed camera and waveform shapes, and the condition of beads was examined by a low magnification camera as well. It was found that the worn contact tip had caused to shift the contact point between the tip and the welding wire which resulted in nonuniform beads. In addition, the worn contact tip had changed the welding resistance and brought about the arc instability during welding.