• Journal of IKEEE
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• v.11 no.1 s.20
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• pp.38-45
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• 2007

A new 8-bit single-slope ADC using analog RAMP generator with digitally controllable dynamic range has been proposed and simulated for column level or per-pixel CMOS image sensor application. The conversion gain of ADC can he controlled easily by using frequency divider with digitally controllable diviber ratio, coarse/fine RAMP with class-AB op-amp, resistor strings, decoder, comparator, and etc. The chip area and power consumption can be decreased by simplified analog circuits and passive components. Proposed frequency divider has been implemented and verified with 0.65um, 2-poly, 2-metal standard CMOS process. And the functional verification has been simulated and accomplished in a 0.35$\mu$m standard CMOS process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1347-1352
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• 2009

Magnetic force driven six degree-of-freedom active vibration isolation system is developed. The velocity sensor using an electromagnetic principle that is commonly used in the vibration control is investigated since its phase lead characteristic causes an instability problem for a low frequency vibration. A lag-type compensator is adopted to reduce the phase lead and the stability test is performed by using a Bode analysis. The performance of the AVIS is validated by comparing with the passive isolation system by using the frequency responses.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.152-157
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• 1994

A fiber-optic interferometric sensor array capable of passive remote sensing is demonstrated with two sensors at the array head. The signal from a specific sensor could be separated in time domain. The measured sensitivity at signal frequencies of a few kHz and cross talk level between two sensors were about $40{\mu}rad\sqrt{Hz}$and below - 50 dB, respectively.tively.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.5
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• pp.585-589
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• 2009

In this paper, passive direction-finding localization of the emitter using noisy line-of-bearing (LOB) measurements is considered. The performance of the LOB-based emitter localization using linear LSE algorithm is given. The Dependence of the performance on bias of emitter location and sensor trajectory is illustrated using the numerical results.

• The Journal of the Acoustical Society of Korea
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• v.39 no.3
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• pp.191-199
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• 2020

Currently, studies on the estimation algorithm based on compressive sensing are actively underway, but to the best of our knowledge, no study on the performance of the Sparse Spectrum Fitting (SpSF) algorithm in nonuniform sensor arrays has been made. This paper deals with the derivation of the compressive sensing based covariance fitting algorithm extended to the frequency domain. In addition, it shows the performance of directon-of-arrival estimation of the frequency domain SpSF algorithm in non-uniform linear sensor array system and the sensor array failure situation.

• Composites Research
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• v.27 no.4
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• pp.152-157
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• 2014

Non-destructive testing methods of composite materials are very important for improving material reliability and safety. AE measurement is based on the detection of microscopic surface movements from stress waves in a material during the fracture process. The examination of AE is a useful tool for the sensitive detection and location of active damage in polymer and composite materials. FBG (Fiber Bragg Grating) sensors have attracted much interest owing to the important advantages of optical fiber sensing. Compared to conventional electronic sensors, fiber-optical sensors are known for their high resolution and high accuracy. Furthermore, they offer important advantages such as immunity to electromagnetic interference, and electrically passive operation. In this paper, the crack detection capability of AE (Acoustic Emission) measurement was compared with that of an FBG sensor under tensile testing and buckling test of composite materials. The AE signals of the PVDF sensor were measured and an AE signal analyzer, which had a low pass filter and a resonance filter, was designed and fabricated. Also, the wavelength variation of the FBG sensor was measured and its strain was calculated. Calculated strains were compared with those determined by finite element analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2769-2792
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• 2013

In this paper, we propose an authenticated key agreement scheme, TinyIBAK, based on the identity-based cryptography and bilinear paring, for large scale sensor networks. We prove the security of our proposal in the random oracle model. According to the formal security validation using AVISPA, the proposed scheme is strongly secure against the passive and active attacks, such as replay, man-in-the middle and node compromise attacks, etc. We implemented our proposal for TinyOS-2.1, analyzed the memory occupation, and evaluated the time and energy performance on the MICAz motes using the Avrora toolkits. Moreover, we deployed our proposal within the TOSSIM simulation framework, and investigated the effect of node density on the performance of our scheme. Experimental results indicate that our proposal consumes an acceptable amount of resources, and is feasible for infrequent key distribution and rekeying in large scale sensor networks. Compared with other ID-based key agreement approaches, TinyIBAK is much more efficient or comparable in performance but provides rekeying. Compared with the traditional key pre-distribution schemes, TinyIBAK achieves significant improvements in terms of security strength, key connectivity, scalability, communication and storage overhead, and enables efficient secure rekeying.

• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.378-382
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• 2004

A micromachined fluidic structure for the introduction of liquid samples into a chip-based sensor array composed of individually addressable polymeric microbeads has been developed. The structure consists of a separately attached cover glass, a single silicon chip having micromachined channels and microbead storage cavities, and a glass carver. In our sensor array, transduction occurs via colorimetric and fluorescence changes to receptors and indicator molecules that are covalently attached to termination sites on the polymeric microbeads. Data streams are acquired for each of the individual microbeads using a CCD. One of the key parts of the structure is a passive fluid introduction system driven only by capillary force. The velocity of penetration of a horizontal capillary for the device having a rectangular cross section has been derived, and it is quite similar to the Washburn Equation calculated for a pipe with a circular cross section having uniform radius. The test results show that this system is useful in a ${\mu}$-TAS and biomedical applications.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.203-207
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• 2003

Due to the inherent nature of the low flying UAV, obstacle detection is a fundamental requirement in the flight path to avoid the collision from obstacles as well as manned aircraft. In this paper, a preliminary sensor requirements of an obstacle detection system for UAV in low-altitude flight are analyzed, and the automated obstacle detection sensor system is proposed assessing both passive and active sensors such as EO camera, IR, Laser radar, microwave and millimeter radar. In addition, TCAS (Traffic Alert and Collision Avoidance System) are reviewed for the collision avoidance of the manned aircraft system. It is suggested that small-sized radar sensor is the best candidate for the smart UAV because an active radar can provide the real-time informations on range and range rate in the all-weather environment. However, an important constraints on small UAV should be resolved in terms of accommodation of the mass, volume, and power allocated in the payload of the UAV system design requirements.

• 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.