• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1633-1640
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• 2016

In this paper, we propose a open-ended rectangular microstirp patch antenna with fork-shaped feeding structure. This antenna extends the effective bandwidth by transforming single or multi resonant frequency and is designed planar monopole structure with microstrip line to satisfy the WLAN bands (2.4 - 2.484, 5.15 - 5.35, 5.25-5.825 GHz). The substrate is printed in 0.8 mm thickness on an FR-4 board. A commercial 3D simulation tool was used to analyze surface current and electromagnetic field distribution in order to analyze the operation mode and reconfiguration principle of antenna. According to the lengths of individual patches, simulated reflection loss was compared to obtain optimized values. When it was designed with the optimized values, it satisfied WLAN bands (2.380 - 2.710, 4.900 - 5.950 GHz), if the switch is off, and 2.4 WLAN band (2.380 - 2.710 GHz). From the fabricated and measured results, measured results of return loss, gain and radiation patterns characteristics displayed for operating bands.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.189-198
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• 2006

The composition of most engineering materials is heterogeneous at some degree. It is simply a question of scale at which the level of heterogeneity becomes apparent. In the case of cementitious granular materials such as concrete the heterogeneity appears at the mesoscale where it is comprised of aggregate particles, a hardened cement paste and voids. Since it is difficult to consider each separate particle in the topological description explicitly, numerical models of the meso-structure are normally confined to two-phase matrix particle composites in which only the larger inclusions are accounted for. 2-D and 3-D concrete blocks(Representative Volume Element, RVE) are used to simulating heterogeneous concrete meso-structures in the form of aggregates in the hardened mortar with nearly zero-thickness linear or planar interfaces. The numerical sensitivity of these meso-structures are Investigated with respect to the different morphologies of heterogeneity and the different level of coupling constant among fracture mode I, II and III. In addition, a numerically homogenized concrete block in 3-D using Hashin-Shtrikman variational bounds provides an evidence of the effective cracking paths which are quite different with those of heterogenous concrete block. However, their average force-displacement relationship show a pretty close match each other.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.5
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• pp.292-296
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• 2014

We investigated the effect of Ta doping on the dielectric and piezoelectric properties of lead-free $(K_{0.5}Na_{0.5})NbO_3$ ceramics prepared using a conventional ceramic processing. X-ray diffraction analysis revealed that Ta was perfectly substituted into Nb-sites in the range of 0 to 20 at%. As Ta content in the KNN increased, the sinterability of KNN ceramics was significantly degraded while the Ta doping enhanced the piezoelectric constant $d_{33}$, planar mode piezoelectric coupling coefficient ($k_p$), and electromechanical quality factor ($Q_m$). The highest values for $d_{33}$, $k_p$, and $Q_m$ was found to be 156 pC/N, 0.37, and 155, respectively.

• Coupled systems mechanics
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• v.2 no.4
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• pp.329-348
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• 2013

This study aims at observing the coupling behaviours between suspended ceilings and partition walls in terms of their global seismic performance using full-scale shake table tests. The suspended ceilings with planar dimensions of $6.0m{\times}3.6m$ were tested with two types of panels: acoustic lay-in and metal clip-on panels. They were further categorized as seismic-braced, seismic-unbraced, and non-seismic installations. Also, two configurations of 2.7 m high partition wall specimens, with C-shape and I-shape in the plane layouts, were tested. In total, seven ceiling-partition-coupling (CPC) specimens were tested utilizing a unidirectional seismic simulator. The test results indicate that the damage patterns of the tested CPC systems included failure of the ceiling grids, shearing-off of the wall top railing, and, most destructively, numerous partial detachments and falling of the ceiling panels. The loss of panels was mostly concentrated near the center of the tested partition wall. The testing results also confirmed that the failure mode of the non-seismic CPC systems was brittle: The whole system would collapse suddenly all at once when the magnitude of the inputs hit the capacity threshold, rather than displaying progressive damage. Overall, the seismic capacity of the unbraced and braced CPC systems could be up to 1.23 g and 2.67 g, respectively; these accelerations were both achieved at the base of the partition wall. Nonetheless, for practical applications, it is noteworthy that the three-dimensional nature of seismic excitations and the size effect of the ceiling area are parameters that exacerbate the CPC's seismic response so that their actual capacity may be dramatically decreased, leading to important losses even in moderate seismic events.

• Journal of architectural history
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• v.9 no.2 s.23
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• pp.85-100
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• 2000

This paper is a study of the Beaux-Arts discipline of architecture, as it was established during the late nineteenth century in America. It focuses on trio particular modes of vision and representation that were at the heart of the discipline. The paper argues that Beaux Arts vision was centered on what may be called 'planar vision'; a mode of seeing through which the multiple aspects of the architectural design imbedded in the plan were read and re-interpreted. Similarly Beaux-Arts training in drawing required its student to draw within the multiple layers of historical traces; the new design being in effect a new layer placed on often unseen traces of monumental precedent. The theoretical basis of this practice was not based on history but on the concept of composition. Composition, in the French tradition was regarded more a matter of practice than theory. The Anglo-American discourse on composition, on the other hand, formed a body of theoretical literature based on formalist assumptions. There was, however, a fundamental gap between these formalist theories of composition and the 'layered' modes of vision and drawing involved in the design process. This practice leaned more on the modern romantic notion of 'intuition' for its theoretical basis, once again forming an immanent conflict with the mimetic practice of classical and historical architecture. The paper draws a picture of a discipline centered on a 'theory of the plan,' a potentially modern discipline integrated with classical forms and details. It was clearly effective as a practice. However, structured by conflicts between theory and practice, history and form, mimesis and intuition, the Beaux-Arts was unable to defend itself at the philosophical and theoretical level the modernists engaged their attacks on this system. At the same time, the paper poses the question of how different modern architecture is from this system. Is not the 'theory of plan,' in its many transformations and guises, still the central discipline of twentieth century modern architecture, and is it not structured by basically the same kind of conflicts and paradox that were immanent to the Beaux-Arts system.

• Korean Journal of Crystallography
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• v.11 no.1
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• pp.22-27
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• 2000

The structure of cis-(malonato)[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II) with a potent anticancer activity has been determined by the X-ray crystallographic method. Crystal data are as follows: Pt(C/sub 11/H/sub 20/N₂O/sub 6/), M/sub 4/=471.38, monoclinic, P2₁, a=7.112(1), b=33.615(3), c=7.135(1)Å, β=116.80(1)°, V=1522.6(3)Å, and Z=4. The two independent molecules with very similar structures are approximately related by pseudo two-fold screw axis symmetry, which makes the monolinic cell look like the orthorhombic cell with one molecule in the asymmetric unit and space group C222₁. The crystal packing mode is similar to that of the analogue with the dimethyl substituents instead of the isopropyl group. The Pt atom is coordinate to two O and two N atoms in a square planar structure. The six-membered chelate ring in the leaving ligand assumes a conformation intermediate between the half chair and the boat forms. The seven-membered ring in the carrier ligand assumes a twist-chair conformation and the oxolane ring assumes an envelope conformation. Crystal packing consists of the extensive hydrogen-bonding network in the two-dimensional molecular layers and weak van der Waals interactions between these layers.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.20-25
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• 2010

An integrated Mach-Zehnder interferometric sensor operating at 632.8 nm was designed and fabricated by the technology of planar rib waveguides. Rib waveguide based on silica system ($SiO_2-SiO_xN_y-SiO_2$) was geometrically designed to have single mode operation and high sensitivity. It was structured by semiconductor fabrication processes such as thin film deposition, photolithography, and RIE (Reactive Ion Etching). With the power observation, propagation loss measurement by cut-back method showed about 4.82 dB/cm for rib waveguides. Additionally the chromium mask process for an etch stop was employed to solve the core damaging problem in patterning the sensing zone on the chip. Refractive index measurement of water/ethanol mixture with this device finally showed a sensitivity of about $\pi$/($4.04{\times}10^{-3}$).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.4
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• pp.210-214
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• 2016

We investigated the sintering behavior and piezoelectric properties of lead-free $(K_{0.5}Na_{0.5})NbO_3$ ceramics co-doped with excess 0.01 mol ZnO and x mol $MnO_2$, where x was varied from 0 to 0.03. Excess $MnO_2$ addition was found to retard the grain growth and densification during sintering. However, 0.005 mol $MnO_2$ addition improved the piezoelectric properties of 0.01 mol ZnO added $(K_{0.5}Na_{0.5})NbO_3$ ceramics. The planar mode piezoelectric coupling coefficient, electromechanical quality factor, and piezoelectric constant $d_{33}$ of 0.01 mol ZnO and 0.005 mol $MnO_2$ added specimen were 0.40, 304, and 214 pC/N, respectively.

• ETRI Journal
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• v.38 no.5
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• pp.981-987
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• 2016

We present a cost-effective dual polarization quadrature phase-shift coherent receiver module using a silica planar lightwave circuit (PLC) hybrid assembly. Two polarization beam splitters and two $90^{\circ}$ optical hybrids are monolithically integrated in one silica PLC chip with an index contrast of $2%-{\Delta}$. Two four-channel spot-size converter integrated waveguide-photodetector (PD) arrays are bonded on PD carriers for transverse-electric/transverse-magnetic polarization, and butt-coupled to a polished facet of the PLC using a simple chip-to-chip bonding method. Instead of a ceramic sub-mount, a low-cost printed circuit board is applied in the module. A stepped CuW block is used to dissipate the heat generated from trans-impedance amplifiers and to vertically align RF transmission lines. The fabricated coherent receiver shows a 3-dB bandwidth of 26 GHz and a common mode rejection ratio of 16 dB at 22 GHz for a local oscillator optical input. A bit error rate of $8.3{\times}10^{-11}$ is achieved at a 112-Gbps back-to-back transmission with off-line digital signal processing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.682-687
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• 2022

In this paper, the research results on monolithic three-dimensional integrated-circuit (M3DICs) stacked with tunneling field effect transistors (TFETs) are introduced. Unlike metal-oxide-semiconductor field-effect transistors (MOSFETs), TFETs are designed differently from the layout of symmetrical MOSFETs because the source and drain of TFET are asymmetrical. Various monolithic 3D inverter (M3D-INV) structures and layouts are possible due to the asymmetric structure, and among them, a simple inverter structure with the minimum metal layer is proposed. Using the proposed M3D-INV, this M3D logic gates such as NAND and NOR gates by sequentially stacking TFETs are proposed, respectively. The simulation results of voltage transfer characteristics of the proposed M3D logic gates are investigated using mixed-mode simulator of technology computer aided design (TCAD), and the operation of each logic circuit is verified. The cell area for each M3D logic gate is reduced by about 50% compared to one for the two-dimensional planar logic gates.