• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.6
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• pp.482-489
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• 2014

This paper suggests the new network scanning algorithm that makes use of measurement pilot of IEEE 802.11k. The purpose of suggesting this algorithm is to improve the existing network scanning schemes. After introducing new algorithm, this paper shows the difference of time property and energy property between former scanning schemes and new scheme with simulation results. Passive scan has a merit of low-power consumption but it takes too long time to fulfill whole scanning. On the contrary, an advantage of active scan is speed but it consumes more battery power than passive scan. By using measurement pilot's smaller interval than beacon interval, the suggested algorithm can consume less power than active scan does, and also make shorter scanning delay than passive scan does.

• Journal of Korea Multimedia Society
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• v.15 no.11
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• pp.1358-1368
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• 2012

A tag sequence estimation scheme is to estimate the physical sequence of passive RFID tags that are linearly spread using the movement of a RFID reader. Since RFID readers communicate with the passive tags by very weak radio waves, scanning passive tags are unstable. In this paper, we applied round-trip scanning of a reader to enhance the tag sequence estimation. Proposed scheme first determines the turning point of the reader movement, and then estimates the sequence of the tags using the tag sets scanned in each read cycles. Test experiments show that the proposed scheme can improve the estimation accuracy.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.2
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• pp.1-7
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• 2008

In this paper, we have designed a millimeter-wave passive imaging sensor that is able to use remote sensing and security applications. The brightness temperature distribution of a scene is measured with a antenna at an angular resolution of $3^{\circ}$. The sensor is controlled by a PC, achieving a fast performance by using a pan/tilter. The pan/tilter should be able to scan a 2-D image of the scene, with a linear raster scan pattern. The mechanical scans in azimuth and elevation whereby an image of $20{\times}20$ pixels is acquired within less than 400s. Raw images are immediately displayed and stored for postprocessing.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.8
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• pp.159-165
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• 2015

In this paper, we designed and tested of the passive millimeter-wave imaging system in near range. The proposed passive millimeter-wave imaging system consists two parts. The first part is a 94 GHz band millimeter imaging sensor which is coupled to an antenna, two LNAs, and a diode detector. The second part is a control unit. The control unit is consists of the 2-axes Cartesian robot, the data acquisition (DAQ), and imaging program. The 2-axes Cartesian robot should be able to scan a 2-D image of the metalic tools, IC card and plastic objects, with a raster scanning method. The passive millimeter-wave image of $20{\times}20$ pixels is acquired within less than 60s, and is immediately displayed and stored for post processing.In order to improve the image quality, interpolation methods are applied.

• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.87-96
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• 2012

In this research, we describe recent technologies and system requirements of the passive microwave radiometer used in Earth observation satellites. And we classify types of microwave radiometer system for Earth observation satellites according to observation targets and ways to scan and discuss a design method. Also, requirements of passive radiometer for Earth observation missions in the latest practical examples used and developed are analyzed in this research.

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.110-118
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• 2004

The corrosion of pure titanium (CP- Ti Grade 2) and titanium alloy (Ti6Al4V ELI) were studied under various conditions of simulated body fluids. The static immersion test and the electrochemical test were performed in accordance with ISO 10271 : 2001. For the electrochemical test, the open circuit potential was monitored as a function of time, and the cyclic polarization curve was recorded. The corrosion resistance was evaluated from the values of corrosion potential, passivation current density, breakdown potential, and the shape of hysteresis etc. The effects of alloy type, surface condition, temperature, oxygen, and constituents in the fluids such as acid, chloride were estimated. Both specimens had extremely low dissolution rate in the static immersion test. They showed strong passivation characteristics in the electrochemical test. They maintained negligible current density throughout the wide anodic potential range. The passive layer was not broken up to 2.0 V (vs. SCE). The hysteresis and the shift of passivation potential toward the anodic direction was observed during the reversed scan. The passivation process appeared to be accelerated by oxygen in air or that dissolved in the fluids. The passivation also proceeded without oxygen by the reaction of constituents in the fluids. Acid or chloride in the fluids, specially later weakened the passive layer, and then induced higher passivation current density and less shift of passivation potential in the reversed scan. CP-Ti Grade 2 was more reactive than Ti6Al4V ELI in the fluids containing acid or chloride, but thicker layer produced on its surface provided higher corrosion resistance.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.4
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• pp.370-376
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• 2008

Power capacitors is widely used for power factor correction and component of passive filter in the user power systems. Recently, application of non-linear load is gradually increased. Non-linear load produces harmonic components of current. There are series resonance and parallel resonance when capacitors are applied in the user electrical application. If this harmonic component matches resonance, voltage and current is magnified and has severely an influences on capacitor. This paper purposes a new method for the magnitude of voltage and current by the frequency scan analysis without equivalent circuit for the actual circuit at the resonance condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.570-574
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• 1993

This paper proposes a new method of estimating the position and heading angle of a mobile robot moving on a flat surface. The proposed localization method utilizes two passive beacons and a single rotating ultrasonic sensor. The passive beacons consist of two cylinders with different diameters and reflect the ultrasonic pulses coming from the sonar sensor mounted on the mobile robot. The geometric parameter set of beacon is acquired from the sonar scan data obtained at a single mobile robot location using a new data processing algorithm. Form this parameter set, the position and heading angle of the mobile robot is determined directly. The performance and validity of the proposed method are evaluated using two beacons and a single sonar sensor attached at the pan-tilt device mounted on a mobile robot, named LCAR, in our laboratory.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.474-477
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• 2005

In tactical theater, it is crucial to detect ground moving targets and to locate them precisely. This problem can be resolved by using SAR (Synthetic Aperture Radar) sensors providing GMTI (Ground Moving Target Indication) capability. In general, to implement a robust GMTI sensor is not simple because of the strong competitions between target signals and clutter signals on the ground, and low speed of moving targets. Contrary to the case that a delay canceller is mostly suitable for ground surveillance radars, DPCA (Displaced Phase Centered Antenna) or STAP (Space Time Adaptive Processing) techniques have been adapted for GMT! function of modem airborne radars. In this paper, anew scheme of DPCA using two passive antennas with vertical separation is proposed, which also provides good clutter cancellation performance. The proposed scheme enables us to scan straight ahead of the carrying platform that is impossible with typical DPCA configuration. Simulations using various conditions have been performed to validate the proposed scheme, and the results are acceptable.

• Journal of Information Display
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• v.6 no.3
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• pp.30-35
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• 2005

We have developed a paper-like display using polymer particles charged triboelectrically. By using a toner-type display with a simple structure, we continued that polymer particle movement is controlled by only a voltage difference between scan and data electrode. We fabricated a diagonal 2.4 inch panel on the glass substrate and successfully produced an image by the passive driving method with operating voltages of about ${\pm}$ 120 V. The contrast ratio was 4:1.