• Spatial Information Research
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• v.3 no.2
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• pp.191-204
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• 1995

The data model is a system model which abstracts the spatial and nonspatial fea¬tures of the real world. A system defines through its data model a framework for the inner rep¬resentation of and connections with the outside world. The spatial query language is one of the most efficent framework for defining connection with outside world in the GIS. Existing GIS uses a spatial data model based on relational data model. Therefore, it has some difficulties in data abstraction and representing complex objects through inheritance. In this paper, we pro-pose an object oriented data model-Topological Object Model(TOM). TOM combines object model in ODMG and the planer topological object. Based on this model, we present an object-oriented spatial query language-OQL/Geo. OQL/Geo extends OQL in ODMG and represents TOM effectively. It also provides several operators such as geometric, topological and visible ope-rators. Moreover, it represents with diverse flexivility the request for complex spatial analysis and presentation of query results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.1963-1970
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• 1998

In this paper, a two-dimensional slotline coupling structure is proposed for the planar active phased array antenna system with scanning the beam by coupled oscillators without phase shifters. The operating characteristics are analyzed and experimentally demonstrated. The proposed two-dimensional slotline coupling structure consists of $|{=}|$-type slotline in the ground plane for the coupling of E-plane and H-plane. From the simulation results of coupling strength with the variation of width, length and the number of slotlines, the optimal coupling structure is proposed and applied to $2{\times}5$ elements of planear phased array antenna. The experimental results show that the beamwidth of E-plane and H-pland are $42^{\circ}$ and $15^{\circ}$, respectivly, and the scanning range is from $-20^{\circ}$ to $15^{\circ}$ from the broadside. Therefore, it is shown the two-dimensional slotline coupling structure for oscillator-type active phased array antenna can be applied to the planar phased array antenna system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.896-905
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• 2004

In this paper, the design, fabrication and experiment on a planar array antenna with a flat-topped radiation pattern for a mobile base station antenna were described. The current distribution of an antenna aperture, which is easily realizable in a feeding network compared with the conventional one of sin(x)/x was optimized for shaping a desired flat-topped radiation pattern. The planar array antenna designed in this paper has a rectangular lattice and is composed of array elements of 16${\times}$8. Each radiating element, which is a microstrip element fed coaxially, has a linear vertical polarization and the feed network which use a Wilkinson power divider and a 180$^{\circ}$ ring hybrid coupler as a base element is designed. The flat-topped radiation pattern with 90$^{\circ}$ is shaped by 16 array elements with the element spacing of 0.55 λ$_{ο}$ in the azimuth plane, and the normal radiation pattern with 10$^{\circ}$ is shaped by 8 array elements with the element spacing of 0.65 λ$_{ο}$ in the elevation plane. Also, the planar array antenna is symmetrically divided into four parts. It consists of one hundred-twenty-eight radiating elements, thirty-two 1-4 column dividers, low 1-8 row dividers and one 1-4 input power divider. In order to verify electrical performances of the planar way antenna proposed in this paper, the experimental breadboard operated in tile band of 1.92～2.17 GHz(IMT2000 band) was fabricated, and its experimental results were a good agreement with simulation ones.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.120-126
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• 2006

A grating-assisted fiber coupler(GAFC), which consists of a thin-film waveguide with grating and circular optical fiber, is proposed and the optimized power coupling is evaluated by using a technique amenable to rigorous longitudinal modal transmission-line theory(L-MTLT). In addition, novel criteria to couple an optical signal incident through the grating waveguide to a single-mode optical fiber are proposed. The numerical result reveals that the optimized power coupling occurs at minimum-gap condition between rigorous modes rather than for the conventional phase-matching condition.

• Transactions of the Society of Information Storage Systems
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• v.8 no.2
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• pp.44-49
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• 2012

We measured the surface flatness of both sides for refractive media using the transmitted digital holography method. To enhance the accuracy of the result, phase-shifting system was used. With two different phase modulation of reference beam, the phase profile of object can be easily obtained. Thus, we proposed the surface measurement method which can measure large area fast, compared with conventional methods. To guarantee the reliability of obtained result, we compared with Zygo measurement system. With the proposed method, the surface flatness of $3.45{\mu}m$ resolution could be obtained.

• Journal of the Korean Institute of Intelligent Systems
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• v.5 no.4
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• pp.77-86
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• 1995

The new architecture that fuzzy logic control(FLC) with difficulties for tuning membership function (MF) is parallel with neural networks(NN) to be learned from the output of FLC is proposed. Therefore proposed scheme has the characteristics to utilize the expert knowledge in design process, to be learned during the operation without any learning mode. In this architecture, the function of the FLC is to supply the sliding surface which is constructed on the phase plane by rule base for giving the desired control characteristics and learning criterion of NN and the stabilization of the control performance before NN is learned, The function of the NN is to let the system trajectory be tracked to the sliding surface and reached to the stable point.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.612-619
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• 2016

In this paper, a dual band electrical beam tilting array antenna with bi-directional directivity is designed. Radiating element operates at dual-resonance frequencies and is designed as planar dipole using PCB. In order to tilt the main beam, the phase delay line is designed by use of only the phase shifting line of a $50\Omega$ microstrip line for broadband. The designed antenna has tilting angle of $0^{\circ}$ to ${\pm}8^{\circ}$. For validation of the designed antenna specification, the array antenna is fabricated and the performances are measured. Comparison between theory and experiment shows good agreement.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.513-526
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• 2005

The objectives of this study are to perform extensive analysis on internal mass motion for a wider parameter space and to provide suitable design criteria for a broader applicability for the class of spinning space vehicles. In order to examine the stability criterion determined by a perturbation method, some numerical simulations will be performed and compared at various parameter points. In this paper, Ince-Strutt diagram for determination of stable-unstable regions of the internal mass motion of the spinning thrusting space vehicle in terms of design parameters will be obtained by an analytical method. Also, phase trajectories of the motion will be obtained for various parameter values and their characteristics are compared.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.3
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• pp.269-276
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• 2011

This paper proposes a novel control method using phase plane for a hydraulic biped humanoid robot. In biped walking control, it is much more difficult to control the posture of a biped robot in the coronal plane because the supporting area formed by the both feet in the coronal plane is much narrower than that of the sagittal plane. When the biped robot walks stably, the phase portrait of the pelvis in the coronal plane makes an elliptical shape. From this point of view, we develop an ankle torque controller and a foot placement controller for tracking the desired phase portrait during walking. We design these controllers by using simulations of a simplified compass gait biped model to regulate the desired phase portrait of pelvis. The effectiveness of the proposed control method is proved through full-body dynamic walking simulations and real experiments of the SARCOS hydraulic biped humanoid.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.1
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• pp.68-74
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• 2008

The substrate integrated waveguide (SIW) structure can be approximated as the rectangular waveguide using common dielectric substrate with via-holes. To realize reflection-type resonator, $50-{\omega}$ microstrip line can be used for coupling with the center plane of the cavity. The oscillator is designed to operate at 9.45 GHz using the reflection-type SIW cavity resonator. The phase noise of oscillator shows -98.1dBc/Hz at 100 KHz offset. In experiment, the reflection type SIW cavity resonator improves the loaded quality factor making the low phase noise oscillator possible. Due to the entirely planar structure of this resonator, this technique can also be adequate in oscillator applications for a low cost and low phase noise performance.