• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.1
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• pp.133-143
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• 1996

The constant modulus algorithm (CMA), one of the widely used blind equalization algorithms, equalizes channels using the second-order statistic of equalizer outputs. The performance of the CMA for multi-level signals such as the quadrature amplitude modulation (QAM) signal degrades because the CMA maps all signal power onto a single modulus. in this paper, to improve the equalization performance of a QAM system, we propose a shell partitioning method based on error magnitude. We assume the probability distribution of an equalizer output as Gaussian, and obtain decision boundaries by maximum likelihood estimation based on the fact that the distribution of the equalizer output power is noncentral $x^2$. The proposed CMA constructs a multi-moduli equlization system based on the fact that each shell separated by decision boundaries employs a single modulus. Computer simulation results for 32-QAM and 64-QAM show the effectiveness of the proposed algorithm.

• Journal of the Korean GEO-environmental Society
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• v.17 no.1
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• pp.39-48
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• 2016

In this study, it can be shortened tunnel construction work period by introducing a single-shell tunnel does not placing the secondary concrete lining, a global research trend, reduction of the cost of the lining placement and number of benefits that can ensure the safety of long-term tunnel with a single shell it was to study the tunnel method. First, we analyze the design and construction practices relating to delete lining of the domestic design and construction practices and a comprehensive analysis of the stability study found a rock in good condition interval (1~3 grades), we propose that the lining uninstalled. In the case of domestic changes on the ground floor is very heavy underfoot conditions many so tunneling method by single shell as ground conditions are good and one preferred the water points that apply in less soil, the soil health and poor sections (4~5 grades) reflecting with respect to the concrete lining that is expected reasonable.

• Advances in nano research
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• v.12 no.5
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• pp.483-488
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• 2022

The present work is an attempt to study the vibration analysis of the single-walled carbon nanotubes (SWCNTs) under the effect of the surface irregularity using Donnell's model. The surface irregularity represented by the parabolic form. According to Donnell's model and three-dimensional elasticity theory, a novel governing equations and its solution are derived and matched with the case of no irregularity effects. To understand the reaction of the nanotube to the irregularity effects in terms of natural frequency, the numerical calculations are done. The results obtained could provide a better representation of the vibration behavior of an irregular single-walled carbon nanotube, where the aspect ratio (L/d) and surface irregularity all have a significant impact on the natural frequency of vibrating SWCNTs. Furthermore, the findings of surface irregularity effects on vibration SWCNT can be utilized to forecast and prevent the phenomena of resonance of single-walled carbon nanotubes.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.50-57
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• 2013

This describes the formulation for the free vibration of joined conical-cylindrical shells with uniform thickness using the transfer of influence coefficient. This method was developed based on successive transmission of dynamic influence coefficients, which were defined as the relationships between the displacement and the force vectors at arbitrary nodal circles of the system. The two edges of the shell having arbitrary boundary conditions are supported by several elastic springs with meridional/axial, circumferential, radial and rotational stiffness, respectively. The governing equations of vibration of a conical shell, including a cylindrical shell, are written as a coupled set of first order differential equations by using the transfer matrix of the shell. Once the transfer matrix of a single component has been determined, the entire structure matrix is obtained by the product of each component matrix and the joining matrix. The natural frequencies and the modes of vibration were calculated numerically for joined conical-cylindrical shells. The validity of the present method is demonstrated through simple numerical examples, and through comparison with the results of previous researchers.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.690-700
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• 1998

Rubber-toughened particles which are used in the field of chemical engineering are used to increase the fracture toughness of thermoset resin. The application of Core-Shell particles, one of rubber-toughened particles, as a filler for dental composite or restoration have not been examined. The purpose of this study was to evaluate possible use of Core-Shell particles for dental composite, and the hypothesis was that additional toughening mechanisms are activated by the addition of Core-Shell particles. After blending 50vol% quartz with Bis-GMA/TEGDMA resin matrix, the experimental resins were made by the addition of Core-Shell particles with varied content level as 0, 2.5, 5, 7.5, 10, 12.5, 15, and 20wt%. Fracture toughness was determined on three-point bending specimen with single-edge notch according to ASTM-E 399. Also, flexural properties, that is, strength and modulus were measured by three-point bending testing. Fractogragh of fracture toughness specimen was observed using SEM (JEOL 6400 SEM, MA). The following results from this study were obtained ; 1. Fracture toughness of composite resin added 2.5wt% Core-Shell particles was significantly higher than control group ($p{\leq}0.05$). 2. Flexural properties were decreased with increasing Core-Shell particle content, which showed a correlation statistically ($p{\leq}0.05$). 3. A toughening mechanism such as lamination and microcrack was observed in specimen determined high fracture toughness. 4. The dispersion of Core-Shell itself and quartz filler particles was limited present high content of Core-Shell particles, which decreased a resulting mechanical properties of composites. These results suggest that adequate Core-Shell particles can be used to enhance mechanical properties included toughening for dental composites.

• Magazine of korean Tunnelling and Underground Space Association
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• v.4 no.2
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• pp.72-80
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• 2002

• Magazine of korean Tunnelling and Underground Space Association
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• v.4 no.3
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• pp.14-22
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• 2002

• Magazine of korean Tunnelling and Underground Space Association
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• v.4 no.1
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• pp.73-86
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• 2002

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.553-553
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• 2012

The artificial shells of hard inorganic nanocomposites on individual cells would protect the cells physically and chemically, and control cell division. These emerging properties could be combined with cell-surface functionalizations for applications to cell-based sensors and assays as well as for fundamental studies on single-cell biology. In this work, individual Chlorella cells were encapsulated within a silica/titania nanocomposite shell in a biocompatible fashion that utilized a designed peptide, RKKRKKRKKRKKDDDDDDDD, as a catalytic template for formation of both $SiO_2$ and $TiO_2$ on the cell surface. The cell viability was maintained, and the division of the encapsulated Chlorella cells was controlled. The cell viability was enhanced compared with the $TiO_2$-shell formation. In addition, the incorporation of $TiO_2$ to the shell made it possible to anchor the ligands of interest to the shell via catechol chemistry. All in all, the combination of biological $SiO_2$ and abiolgical $TiO_2$ for the shell formation gave more tunability of the artificial shells compared with the $SiO_2$ or $TiO_2$ shells only.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.4
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• pp.155-159
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• 2008

In this work, we report synthesis of free-standing ZnO/Zn core-shell micro-polyhedrons using metal Zn pellets as a source material by the thermal chemical vapor deposition process. Scanning and transmission electron microscopy measurements were introduced to investigate morphologies and structural properties of as-grown ZnO/Zn core-shell micro-polyhedrons. It was found that micro-polyhedrons were composed of inner single-crystalline metal Zn surrounded by single-crystalline ZnO nanorod arrays. The inner single crystalline metal Zn with micro-scale diameter has a hexagonal crystal structure. Diameter and height of ZnO nanorods covering the metal Zn surface are below 10 nm and 100 nm, respectively. It was also confirmed that c-axis oriented ZnO nanorods are single crystalline with a hexagonal crystal structure.