• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.21-28
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• 2016

The Wide Area Differential Global Positioning System (WADGPS) that uses a number of Global Navigation Satellite System (GNSS) reference stations are implemented with various types and provide services as it can service a wide range of areas relatively. This paper discusses a constellation design of reference stations and performance analysis of the WADGPS. It presented performance results of static and dynamic users when wide area correction algorithm was applied using eight reference stations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.1
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• pp.38-45
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• 2010

A new readout circuit involving a pixel-level reset control was studied for 2-D long wavelength infrared focal plane arrays. The integration time of each pixel can be optimized individually and automatically. Hence, the readout circuit has a wide dynamic range and good signal-to-noise ratio characteristics. The readout circuit was fabricated with a $0.35{\mu}m$ 2-poly 4-metal CMOS process for a $128{\times}128$ long wavelength infrared HgCdTe array with a pixel size of $50{\mu}m{\times}50{\mu}m$. The smart reset control with two-step background suppression improves the signal-to-noise ratio to 87dB and the dynamic range to 95.8dB.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.62-67
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• 1999

In this letter, a scheme for increasing the input power dynamic range of wavelength converters based on cross-gain modulation (XGM) in semiconductor optical amplifiers (SOA/s) is proposed. We investigate the effect of input pump and probe powers on the power penalty, the measure of performance for the wavelength converters. As a result, we show that the optimal bit error rate (BER) performance can be obtained when the probe power is kept 3 dB weaker than the pump power. Using this characteristic, we propose the wavelength converter scheme that controls the probe power level by monitoring the input pump power and adjusting the bias current of probe source accordingly. Consequently, the wavelength converter for wide input power dynamic range can be implemented. We show that an input power dynamic range of more than 20 dB at 2.5 Gb/s is achievable.

• Journal of Sensor Science and Technology
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• v.24 no.2
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• pp.131-136
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• 2015

This paper presents a wide dynamic range complementary metal oxide semiconductor (CMOS) image sensor with column capacitor and feedback structure. The designed circuit has been fabricated by using $0.18{\mu}m$ 1-poly 6-metal standard CMOS technology. This sensor has dual mode operation using combination of active pixel sensor (APS) and passive pixel sensor (PPS) structure. The proposed pixel operates in the APS mode for high-sensitivity in normal light intensity, while it operates in the PPS mode for low-sensitivity in high light intensity. The proposed PPS structure is consisted of a conventional PPS with column capacitor and feedback structure. The capacitance of column capacitor is changed by controlling the reference voltage using feedback structure. By using the proposed structure, it is possible to store more electric charge, which results in a wider dynamic range. The simulation and measurement results demonstrate wide dynamic range feature of the proposed PPS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.270-275
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• 2018

Method for improving the image quality are divided into a tone mapping method and a retinex theory based method. Typical example of the image quality enhancement method using tone mapping method is one using image characteristics like histogram. In this paper, we propose a hardware design of real-time wide dynamic range algorithm based on tone mapping method for image quality enhancement. The proposed method divides the image into the luminance and chroma components and then improves the chroma region based on the variation of the luminance component. Adding to that, it is designed to be compatible with the existing 8-bit signal, using high quality image with 12-bit extended signal according to the desired flow. As a result of simulation, it is confirmed that the image quality is improved, and the hardware design is confirmed that the real-time operations is possible at the maximum frequency at 138.26MHz.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.1
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• pp.18-25
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• 2018

In this paper, we present a low-power implementation of the multi-channel hearing aid system using a general-purpose DSP chip. The system includes an acoustic amplification algorithm based on Wide Dynamic Range Compression (WDRC), an adaptive howling canceller, and a single-channel noise reduction algorithm. To achieve a low-power implementation, each algorithm is re-constructed in forms of integer program, and the integer program is converted to the assembly program using BelaSigna(R) 250 instructions. Through experiments using the implementation system, the performance of each processing algorithm was confirmed in real-time. Also, the clock of the implementation system was measured, and it was confirmed that the entire signal processing blocks can be performed in real time at about 7.02MHz system clock.

• Journal of the Korean Physical Society
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• v.73 no.12
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• pp.1821-1826
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• 2018

Uniformity is a key feature of state-of-the-art infrared focal planed array (IRFPA) and infrared imaging system. Unlike traditional infrared telescope facility, a ground-based infrared radiant characteristics measurement system with an IRFPA not only provides a series of high signal-to-noise ratio (SNR) infrared image but also ensures the validity of radiant measurement data. Normally, a long integration time tends to produce a high SNR infrared image for infrared radiant characteristics radiometry system. In view of the variability of and uncertainty in the measured target's energy, the operation of switching the integration time and attenuators usually guarantees the guality of the infrared radiation measurement data obtainted during the infrared radiant characteristics radiometry process. Non-uniformity correction (NUC) coefficients in a given integration time are often applied to a specified integration time. If the integration time is switched, the SNR for the infrared imaging will degenerate rapidly. Considering the effect of the SNR for the infrared image and the infrared radiant characteristics radiometry above, we propose a-wide-dynamic-range NUC algorithm. In addition, this essasy derives and establishes the mathematical modal of the algorithm in detail. Then, we conduct verification experiments by using a ground-based MWIR(Mid-wave Infared) radiant characteristics radiometry system with an Ø400 mm aperture. The experimental results obtained using the proposed algorithm and the traditional algorithm for different integration time are compared. The statistical data shows that the average non-uniformity for the proposed algorithm decreased from 0.77% to 0.21% at 2.5 ms and from 1.33% to 0.26% at 5.5 ms. The testing results demonstrate that the usage of suggested algorithm can improve infrared imaging quality and radiation measurement accuracy.

• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.114-119
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• 2008

Wide dynamic range active pixel sensor(APS) using a charge pump circuit has been designed by using 2-poly 4-metal $0.35{\mu}M$ standard CMOS technology. The structure of the proposed APS is similar to the structure of the conventional 3-Tr APS. The proposed unit pixel consists of one photodiode and three MOSFETs. Using a charge pump circuit, the dynamic range of the proposed APS is increased, compared to the conventional 3-Tr APS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.11
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• pp.919-927
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• 2013

In this paper, we present a perception-based tone mapping technique using histogram modification for displaying high dynamic range image. HDR (high dynamic range) tone mapping algorithms are used to display HDR image on LDR (low dynamic rnage) devices. Although perception-based tone mapping methods provides better performance, it dose not always produce good results for a wide variety of images. The proposed method reduces dynamic range by using the perception-based tone mapping function and histogram modification. A derivative of perception-based tone mapping function is used as constraint function of histogram and additional compensation process is performed. This method not only improves contrast by adopting different constraints on each pixel value, but also preserves more visual details. In order to prevent over enhancement, histogram modification technique is applied. Furthermore, it can control the rate of image contrast using control parameters. Subjective and objective evaluations show that proposed algorithm is better than existing algorithms.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.829-832
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• 2005

This paper describes a wide-range dual-loop Delay Locked Loop (DLL) using Voltage Controlled Delay Line (VCDL) based on Transmission Gate(TG) inverters. One loop is used when the minimum VCDL delay is greater than a half of $T_{REF}$, the reference clock period. The other loop is initiated when the minimum delay is less than $0.5{\times}T_{REF}$. The proposed VCDL improves the dynamic operation range of a DLL. The DLL with a VCDL of 10 TG inverters provides a lock range from 70MHz to 700MHz when designed using $0.18{\mu}m$ CMOS technology with 1.8 supply voltage. The DLL consumes 11.5mW for locking operation with a 700MHz reference clock. The proposed DLL can be used for high-speed memory devices and processors, communication systems, high-performance display interfaces, etc.