• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.425-429
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• 2014

Half-metallic nanostructure is highly applicable in the field of Spintronics and electronic device technology. We examine the electronic properties of a ferrocene-based nanowire as a possible candidate for a half-metallic nanostructure using VASP and SIESTA. Ferrocene-based nanowire shows high stability in both binding energy simulation and molecular dynamics (MD) simulation. The density of states (DOS) and the projected DOS of the ferrocene-based nanowire indicate that one-dimensional clustering of ferrocene molecules can be explained because of p-d orbital hybridization between iron and carbon. Half-metallic property and energy dispersion at the Fermi level due to one-dimensional structure is also observed from the DOS results.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3265-3268
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• 2013

The multi-hydrogen bonded systems with the solvated electrons are investigated at the B3LYP/6-311++$G^{**}$ basis set level. The symmetrical linear geometrical characteristic is common for the dimer systems, while for the tetramer system, the tetrahedron configuration is generated. The NBO charge analyses demonstrate that the multi-hydrogen-multi-electron (mH-ne) coupling exist in these anion systems, as is supported by the electrostatic potential and the molecular orbital analyses. The positive chemical shift value of the central hydrogen ($H_c$) and the negative chemical shift value of the terminal hydrogen ($H_t$) indicate that the $H_c$ is electronegative while the $H_t$ is electropositive, respectively. Strong coupling between two central hydrogen atoms is demonstrated by the large spin-spin coupling constants. The solvated electron donates significant contributions for the stability of these systems.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.191-196
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• 2006

In GPS Positioning, the error of satellite orbit will affect user's position accuracy directly, it is important to determine the satellite orbit precise. The real-time orbit is needed in kinematic GPS positioning, the precise GPS orbit from IGS would be delayed long time, so orbit prediction is key to real-time kinematic positioning. We analyze the GPS predicted ephemeris, on the base of comparison of EKF and UKF, a new orbit prediction method is put forward based on UKF in this paper, the result shows that UKF improves the orbit predicted precision and stability. It offers a new method for others satellites orbit determination as Galileo, and so on.

• Bulletin of the Korean Chemical Society
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• 제35권5호
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• pp.1479-1484
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• 2014

Based on the full optimized molecular geometric structures at B3LYP/cc-pvtz method, a new designed compound, 4,6,8-trinitro-4,5,7,8-tetrahydro-6H-furazano[3,4-f ]-1,3,5-triazepine was investigated in order to look for high energy density compounds (HEDCs). The analysis of the molecular structure indicates that the seven-membered ring adopts chair conformation and there exist intramolecular hydrogen bond interactions. IR spectrum and heat of formation (HOF) were predicted. The detonation velocity and pressure were evaluated by using Kamlet-Jacobs equations based on the theoretical density and condensed HOF. The bond dissociation energies and bond orders for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that $N_1-N_6$ bond is the trigger bond. The crystal structure obtained by molecular mechanics belongs to $Pna2_1$ space group, with lattice parameters Z = 4, a = 15.3023 ${\AA}$, b = 5.7882 ${\AA}$, c = 11.0471 ${\AA}$, ${\rho}=2.06gcm^{-3}$. In addition, the analysis of frontier molecular orbital shows the title compound has good stability and high chemical hardness.

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.2077-2082
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• 2009

The conformational and electronic properties of 2-cyano-3-(thiophen-2-yl)acrylic acid (TCA) in analogues used as sensitizers in dye-sensitized solar cells was examined using density functional theory (DFT) and natural bond orbital analysis methods. A relaxed potential energy surface scan was performed on NKX-2677 by rotating the C-C bond between the thiophene and cyanoacrylic acid which yielded activation energy barriers of about 13 kcal/mol for both E and Z configurations. The most stable conformation of all the analogues was E-180 except for NKX-2587 which has an electrostatic repulsion between the oxygen of the coumarin and the nitrogen of the cyanoacrylic acid. The increase in the electron delocalization between the thiophene and cyanoacrylic acid influences the stability for most of the analogues. But for NKX-2600, even though there was a greater deviation from the planarity of TCA, the stability was mainly due to the presence of a weak hydrogen bond between the hydrogen of the methyl group of the amine located in the donor moiety and the nitrogen of the cyanoacrylic acid. The vertical excitation energies of the analogues containing TCA were calculated by time-dependent DFT method. There were slight differences in its vertical excitation energies but the oscillator strengths vary significantly especially in the case of NKX-2600.

• Archives of Plastic Surgery
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• 제38권3호
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• pp.273-278
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• 2011

Purpose: It has always been an aspiration for Asians to look more balanced and feminine, considering their facial features regarding relatively flat midface with marked prominences of the zygoma. Many studies have been dealt in this subject. However, the authors would like to emphasize the concept and introduce the technique of repositioning of the malar complex to a cosmetically beneficial point and stationing it on proper position by fixation on zygoma body and arch. Methods: From January 1998 to December 2007, this method was performed in 50 patients of mild to moderate prominence and malposition of the malar complex. A simplified technique of lateral orbital osteotomy and oblique osteotomy on zygomatic arch through intraoral and preauricular incision was developed. Then, liberal malar complex can be moved to a supero-posterior direction and repositioned to a more cosmetically beneficial point. To maintain the stationed position and to protect from vector affected by the attached masticating muscle to zygomatc bone, fixation was done on both zygoma body and arch. Results: We have obtained satisfactory results using this procedure without any observable complications. The advantages of this procedure are proper exposure, inconspicuous scar, safe, more natural contour, improved stability, and shorter healing time. Conclusion: The authors suggest that reduction malarplasty should be approached with underlying concept of repositioning and fixation. In mild moderate malar prominent cases, our technique will provide with maintenance of aesthetic concept, equal to the malar reduction performed under coronal approach and provide with more natural facial contour with stability even with less invasive surgical approach.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.592-602
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• 2021

Thorium compounds have attracted immense scientific and technological attention with regard to both fundamental and practical implications, owing to unique chemical and physical properties like high melting point, high density and thermal conductivity. Hereby, we investigate the mechanical and thermodynamic stability and report on the structural, electronic and magnetic properties of new silicon-doped cubic ternary thorium phosphides ThSi_xP_1-x (x = 0, 0.25, 0.5, 0.75 and 1). The first-principles density functional theory procedure was adopted within full-potential linearized augmented plane wave (FP-LAPW) method. The exchange and correlation potential terms were treated within Generalized-Gradient-Approximation functional modified by Perdew-Burke-Ernzerrhof parameterizations. The proposed compounds showed mechanical and thermodynamic stable structure and hence can be synthesized experimentally. The calculated lattice parameters, bulk modulus, total energy, density of states, electronic band structure and spin magnetic moments of the compounds revealed considerable correlation to the Si substitution for P and the relative Si/P doping concentration. The electronic and magnetic properties of the doped compounds rendered them non-magnetic but metallic in nature. The main orbital contribution to the Fermi level arises from the hybridization of Th(6d+5f) and (Si+P)3p states. Reported results may have potential implications with regard to both fundamental point of view and technological prospects such as fuel materials for clean nuclear energy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.713-716
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• 2001

In many papers, the electrochemical analysis of LiMn$_2$O$_4$shows the transition results of Mn$^{3+}$ ion. Charge ordering is accompanied by simultaneous orbital ordering due to the Jahn-Teller effect in Mnl$^{3+}$ ions. To analyze the cycle performance of LiMn$_{2-x}$Cu$_{x}$ O$_4$as the cathode of 4 V class lithium secondary batteries, XRD, TGA analysis were conducted. Although the cycle performance of the LiMn$_{2-x}$Cu$_{x}$ O$_4$was improved from pure LiMn$_2$O$_4$, the discharge capacity was significantly lower than LiCoO$_2$. In this paper, We study the Electrochemical characterization and enhanced stability of Cu-doped spinels in the LiMn$_{2-x}$Cu$_{x}$ O$_4$upon initial cycling.l cycling.

• 천문학회보
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• 제39권2호
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• pp.77.1-77.1
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• 2014

Galactic spiral arms are abundant with interesting gaseous substructures. It has been suggested that arm substructures arise from the wiggle instability (WI) of spiral shocks. While the nature of the WI remained elusive, our recent work without considering magnetic fields shows that the WI is physically originated from the accumulation of potential vorticity (PV) generated by deformed shock fronts. To elucidate the characteristics of the WI in more realistic galactic situations, we extend our previous linear stability analysis of spiral shocks by including magnetic fields. We find that magnetic fields reduce the amount of density compression at shocks, making the shock fronts to move toward the upstream direction. Magnetic tension forces from bent field lines stabilize the WI by prevent the generation of PV. When the spiral-arm forcing is F=5% of the centrifugal force of galaxy rotation, the maximum growth rate of the WI is found to be about 1.0, 0.4, and 0.2 times the orbital angular frequency for the plasma parameter ${\beta}=100$, 10, and 5, respectively. Shocks with ${\beta}=1$ are stable to the WI for F=5%, while becoming still unstable when F=10%.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권2호
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• pp.197-203
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• 2000

Maxillary defect may be induced by trauma, inflammation, cyst, tumor and surgical procedure. In case of limited wall defect, free bone graft has been preferred. But it has some problems such as postoperative bone resorption and soft tissue inclusion to recipient site. And we can not use free bone in the case who has inflammation in the donor site. So we used the micro-titanium mesh as reconstructive material for the maxillary wall defect. We had operated 8 patients who were diagnosed as maxillary partial defects from June 1997 to September 1998 in the Chin-Hae military hospital. They were 1 case of antral wall defect, 1 case of palatal wall defect, 5 cases of infra-orbital wall defects and 1 case of oroantral fistula case. As a result, the micro-titanium mesh has shown the morphological stability and biocompatibility and it could be used in case who has infection. And mesh structure could prevent soft tissue ingrowth to bony defect area. Thus it can be used to the case of maxillary partial defect successfully.