• International Journal of Precision Engineering and Manufacturing
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• v.6 no.2
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• pp.50-54
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• 2005

We report a simple, low cost, and reliable method for assembling a multi-walled nanotube (MWNT) to the end of a metal coated scanning probe microscopy (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 dielectric solution were directly assembled onto the apex of the SPM tip due to the attraction by the dielectrophoretic force. The effective measurement of a MWNT -attached SPM tip was demonstrated by direct comparison with AFM images of a standard sample with a bare AFM tip.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.4
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• pp.45-52
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• 1997

This study was carried out to investigate the adsorption characteristics of cationic starches onto BKP, BCTMP and talc. Concentration of the unadsorbed cationic starch contained in the supernatant of the pulp or talc slurries was determined using a spectoscopy method and the adsorption isotherm of cationc starch was constructed. When the equilibrium concentration of the cationic starch was low, almost complete adsorption of the starch onto BKP and BCTMP was observed. This indicates that electrostatic attraction is the main driving force for the adsorption of cationc starches onto pulps. BCTMP adsorbed greater amount of cationic starches than BKP since it contained more anionc functional groups on its surface. The adsorption amount of the cationic starch increased as the cationicity of the starches decreased. Surface charge density of the pulp and starch adsorption increased as the pH of the pulp slurry increased. Adsorption amount of the cationic starch onto talc was lower than that onto the pulp due to its low charge density and hydrophobic surface property.

• Journal of ILASS-Korea
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• v.13 no.1
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• pp.34-41
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• 2008

Molecular dynamic simulations have been carried out to study the effect of the nano-structure substrate and its temperature on cluster laminating. The interaction between substrate molecules and liquid molecules was modeled in the molecular scale and simulated by the molecular dynamics method in order to understand behaviors of the liquid cluster on nano-structure substrate. In the present model, the Lennard-Jones potential is applied to mono-atomic molecules of argon as liquid and platinum as nano-structure substrate to perform simulations of molecular dynamics. The effect of wettability on a substrate was investigated for the various beta of Lennard-Jones potential. The behavior of the liquid cluster and nano-structure substrate depends on interface wettability and function of molecules force, such as attraction and repulsion, in the collision progress. Furthermore, nano-structure substrate temperature and beta of Lennard-Jones potential have effect on the accumulation ratio. These results of simulation will be the foundation of coating application technology for micro fabrication manufacturing.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.662-668
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• 2015

A suspension of titanium nanoparticles (Ti NPs) in liquid sodium (Na) has been proposed as a method to mitigate the violent sodium-water reaction (SWR). The interparticle potential between Ti NPs in liquid Na may play a significant role in the agglomeration of NPs on the reaction surface and in the bulk liquid Na, since the potential contributes to a reduction in the long-term dispersion stability. For the effective control of the SWR with NPs, a physical understanding of the molecular dynamics of NPs in liquid Na is key. Therefore in this study, the nonretarded Van der Waals model and the solvation potential model are employed to analyze the interparticle potential. The ab initio calculation reveals that a strong repulsive force driven by the solvation potential exceeds the interparticle attraction and predicts the agglomeration energy required for two 10-nm Ti NPs to be $4{\times}10^{-17}J$. The collision theory suggests that Ti NPs can be effective suppressors of the SWR due to the high energy barrier that prevents significant agglomeration of Ti NPs in quiescent liquid Na.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2022-2024
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• 2005

Electrical double-layer capacitor (EDLC) is an electrochemical energy storage device in which electric charges only accumulated by a pure electrostatic attraction force are stored on the electrolyte-electrode interface in a form of double layer and separated by the electrolyte. The composite was prepared by mixing nanosize $TiO_2$ and activated carbon through a means of ultrasonic vibration in ethanol solution for 30 min in various mass ratios of $AC:TiO_2$ to form activated carbone-semiconducting oxide composites. Either 1.0 M $LiClO_4/EC-DEC$ or $Et_4NBF_4$/EC-DEC was used as the electrolyte. It was found that with modification of $TiO_2$, the specific capacitance of activated carbon measured at $1mA/cm^2$ was increased from 40 to 50 F/g. This method is unique in comparison the conventional method because it uses semiconducting TiO2 other than electrochemically active materials such as $RuO_2$. The increase in specific capacitance could be attributed to the decrease in electric polarization, caused by the introduction of $RuO_2$.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.36-36
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• 2017

Out of twenty common protein amino acids, there are many kinds of non protein amino acids (NPAAs) that exist as secondary metabolites and exert ecological functions in plants. Mimosine (Mim), one of those NPAAs derived from L. leucocephala acts as an iron chelator and reversely block mammalian cell cycle at G1/S phases. Cysteine (Cys) is decisive for protein and glutathione that acts as an indispensable sulfur grantor for methionine and many other sulfur-containing secondary products. Cys biosynthesis includes consecutive two steps using two enzymes-serine acetyl transferase (SAT) and O-acetylserine (thiol)lyase (OASTL) and appeared in plant cytosol, chloroplast, and mitochondria. In the first step, the acetylation of the ${\beta}$-hydroxyl of L-serine by acetyl-CoA in the existence of SAT and finally, OASTL triggers ${\alpha}$, ${\beta}$-elimination of acetate from OAS and bind $H_2S$ to catalyze the synthesis of Cys. Mimosine synthase, one of the isozymes of the OASTLs, is able to synthesize Mim with 3-hydroxy-4-pyridone (3H4P) instead of $H_2S$ for Cys in the last step. Thus, the aim of this study was to clone and characterize the cytosolic (Cy) OASTL gene from L. leucocephala, express the recombinant OASTL in Escherichia coli, purify it, do enzyme kinetic analysis, perform docking dynamics simulation analysis between the receptor and the ligands and compare its performance between Cys and Mim synthesis. Cy-OASTL was obtained through both directional degenerate primers corresponding to conserved amino acid region among plant Cys synthase family and the purified protein was 34.3KDa. After cleaving the GST-tag, Cy-OASTL was observed to form mimosine with 3H4P and OAS. The optimum Cys and Mim reaction pH and temperature were 7.5 and $40^{\circ}C$, and 8.0 and $35^{\circ}C$ respectively. Michaelis constant (Km) values of OAS from Cys were higher than the OAS from Mim. Inter fragment interaction energy (IFIE) of substrate OAS-Cy-OASTL complex model showed that Lys, Thr81, Thr77 and Gln150 demonstrated higher attraction force for Cys but 3H4P-mimosine synthase-OAS intermediate complex showed that Gly230, Tyr227, Ala231, Gly228 and Gly232 might provide higher attraction energy for the Mim. It may be concluded that Cy-OASTL demonstrates a dual role in biosynthesis both Cys and Mim and extending the knowledge on the biochemical regulatory mechanism of mimosine and cysteine.

• The Journal of Engineering Geology
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• v.19 no.3
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• pp.345-350
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• 2009

The endpoint of the Yangbuk tunnel constructed at the national road between Gyeongju and Gampo is composed of massive cutting because the road is driven through the sides of mountain. PAP(Prestressed Anchor and PC Pannel) retaining wall as a slope stability method was established over this section. Part of the anchor in PAP wall became broken after six months. We performed inverse analysis through its measurements obtained until that time. An geological investigation to confirm the condition of ground layering and the attraction force test to find as to whether some errors might be present in the anchor were made. According to the back analysis, it was turned out that the value with soil parameter 90% that was applied to the original design was pertinent. In the redesign, the permissible stress in the anchor body was changed from 306 kN to 591 kN and 784 kN and the fixation position was increased from 11.0 m to 23.0 m. Nevertheless, five months have passed since the exchange of the anchor, the measurement results validate that stable state has been maintained. This research is considered a case that the immediate maintenance helps prevent the slope accidents.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1424-1430
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• 2013

This paper presents design procedure of the magnetic bearings used for high-speed electric machines and flywheel energy storage systems. Magnetic bearing can be categorized by inner-rotor type and outer-rotor type according to the position of the rotary disc. These two types are applicable based on application environments such as application space, required attraction force, and controllability. Magnetic bearing is generally designed based on the ratio (geometrical coefficient or geometrical efficiency) of pole width to rotor journal radius but proper ratio is only decided by the analysis. This is the difficulty of the magnetic bearing design. In this paper, proper design technology of the inner-rotor type and outer-rotor-type eight pole magnetic bearings is introduced and compared with the FEM analysis results, which verifies the proposed design procedure is suitable to be applied to the design of the magnetic bearings for the industrial applications and flywheel energy storage system.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.599-617
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• 2006

A network model and a Genetic Algorithm(GA) is proposed to solve the simultaneous estimation of the trip distribution and traffic assignment from traffic counts in the congested networks in a logit-based Stochastic User Equilibrium (SUE). The model is formulated as a problem of minimizing the non-linear objective functions with the linear constraints. In the model, the flow-conservation constraints of the network are utilized to restrict the solution space and to force the link flows meet the traffic counts. The objective of the model is to minimize the discrepancies between the link flows satisfying the constraints of flow-conservation, trip production from origin, trip attraction to destination and traffic counts at observed links and the link flows estimated through the traffic assignment using the path flow estimator in the legit-based SUE. In the proposed GA, a chromosome is defined as a vector representing a set of Origin-Destination Matrix (ODM), link flows and travel-cost coefficient. Each chromosome is evaluated from the corresponding discrepancy, and the population of the chromosome is evolved by the concurrent simplex crossover and random mutation. To maintain the feasibility of solutions, a bounded vector shipment is applied during the crossover and mutation.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.3.1-3.1
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• 2011

Over the past decade, the major efforts for lowering the cost of electronics has been devoted to increasing the packaging efficiency of the integrated circuits (ICs), which is defined by the ratio of all devices on system-level board compared to the area of the board, and to working on a larger but cheaper substrates. Especially, in flexible electronics, the latter has been the favorable way along with using novel nanomaterials that have excellent mechanical flexibility and electrical properties as active channel materials and conductive films. Here, the tool for achieving large area patterning is by printing methods. Although diverse printing methods have been investigated to produce highly-aligned structures of the nanomaterials with desired patterns, many require laborious processes that need to be further optimized for practical applications, showing a clear limit to the design of the nanomaterial patterns in a large scale assembly. Here, we demonstrate the alignment of highly ordered and dense silicon (Si) NW arrays to anisotropically etched micro-engraved structures using a simple evaporation process. During evaporation, entropic attraction combined with the internal flow of the NW solution induced the alignment of NWs at the corners of pre-defined structures. The assembly characteristics of the NWs were highly dependent on the polarity of the NW solutions. After complete evaporation, the aligned NW arrays were subsequently transferred onto a flexible substrate with 95% selectivity using a direct gravure printing technique. As proof-of-concept, flexible back-gated NW field effect transistors (FETs) were fabricated. The fabricated FETs had an effective hole mobility of 0.17 $cm2/V{\cdot}s$ and an on/off ratio of ${\sim}1.4{\times}104$. These results demonstrate that our NW gravure printing technique is a simple and effective method that can be used to fabricate high-performance flexible electronics based on inorganic materials.