• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.7
• /
• pp.209-216
• /
• 2000

Recently, Wearable Computers have been applied to medical equipments, inspection system, military and various fields of industries. To support the various application of wearable computer, many researches into the input device for wearable computer have been executed. This paper describes the glove-like hand input system for wearable computer. the characteristics of sensed values, and coupling effects between each sensor. Using these characteristics and coupling effects, the general relation between flexion angles of joints and the values from sensors are proposed as exponential functions. Also, the error range of sensed values is proposed and the glove-like hand input system is calibrated as well by the experiments.

• Proceedings of the KSRS Conference
• /
• 1999.11a
• /
• pp.390-395
• /
• 1999

Ocean Scanning Multispectral Imager (OSMI) is a payload on the Korean Multi-purpose SATellite (KOMPSAT) to perform worldwide ocean color monitoring for the study of biological oceanography KOMPSAT will be launched in the middle of November this year. The radiometric performance of OSMI is analyzed for various gain settings in the viewpoint of the instrument developer for OSMI calibration and application based on its ground performance measurement data for 8 primary spectral bands of OSMI. The radiometric response linearity and dynamic range are analyzed for the image radiometric calibration and the estimation of OSMI image quality for the ocean remote sensing area. The dynamic range is compared with the nominal input radiance for the ocean and the land. The noise equivalent radiance (NER) corresponding to the instrument radiometric noise is compared with the radiometric resolution of signal digitization (1-count equivalent radiance). The best gain setting of OSMI for ocean monitoring is recommended. This analysis is considered to be useful for the OSMI mission and operation planning, the OSMI image data calibration, and users' understanding about OSMI image quality.

• Journal of IKEEE
• /
• v.24 no.3
• /
• pp.719-726
• /
• 2020

A threshold-voltage sensing circuit is proposed to compensate for pixel aging in active matrix organic light-emitting diodes. The proposed threshold-voltage sensing circuit consists of sample-hold (S/H) circuits and a single-ended successive approximation register (SAR) analog-to-digital converter (ADC) with a resolution of 10 bits. To remove a scale down converter of each S/H circuit and a voltage gain amplifier with a signl-to-differentail converter, the middle reference voltage calibration and input range calibration for the single-ended SAR ADC are performed in the capacitor digital-to-analog converter and reference driver. The proposed threshold-voltage sensing circuit is designed by using a 180-nm CMOS process with a supply voltage of 1.8 V. The ENOB and power consimption of the single-ended SAR ADC are 9.425 bit and 2.83 mW, respectively.

• Journal of Mechanical Science and Technology
• /
• v.19 no.8
• /
• pp.1632-1648
• /
• 2005

The effects of Reynolds number on the non-nulling calibration of a typical cone-type five-hole probe have been investigated for the representative Reynolds numbers in turbomachinery. The pitch and yaw angles are changed from - 35 degrees to 35 degrees with an angle interval of 5 degrees at six probe Reynolds numbers in range between $6.60{\times}10^3\;and\;3.17{\times}10^4$. The result shows that not only each calibration coefficient itself but also its Reynolds number dependency is affected significantly by the pitch and yaw angles. The Reynolds-number effects on the pitch- and yaw-angle coefficients are noticeable when the absolute values of the pitch and yaw angles are smaller than 20 degrees. The static-pressure coefficient is sensitive to the Reynolds number nearly all over the pitch- and yaw-angle range. The Reynolds-number effect on the total-pressure coefficient is found remarkable when the absolute values of the pitch and yaw angles are larger than 20 degrees. Through a typical non-nulling reduction procedure, actual reduced values of the pitch and yaw angles, static and total pressures, and velocity magnitude at each Reynolds number are obtained by employing the calibration coefficients at the highest Reynolds number ($Re=3.17{\times}10^4$) as input reference calibration data. As a result, it is found that each reduced value has its own unique trend depending on the pitch and yaw angles. Its general tendency is related closely to the variation of the corresponding calibration coefficient with the Reynolds number. Among the reduced values, the reduced total pressure suffers the most considerable deviation from the measured one and its dependency upon the pitch and yaw angles is most noticeable. In this study, the root-mean-square data as well as the upper and lower bounds of the reduced values are reported as a function of the Reynolds number. These data would be very useful in the estimation of the Reynolds-number effects on the non-nulling calibration.

• Korean Journal of Remote Sensing
• /
• v.16 no.2
• /
• pp.135-143
• /
• 2000

Ocean Scanning Multispectral Imager (OSMI) is a payload on the Korean Multi-Purpose SATellite (KOMPSAT) to perform global ocean color monitoring for the study of biological oceanography. HOMPSAT was launched 21 December 1999. The radiometric performance of OSMI is analyzed for various gain settings in the viewpoint of the instrument developer for OSMI calibration and application based on its ground performance data measured before launch. The radiometric response linearity and dynamic range are analyzed and the dynamic range is compared with the nominal input radiance for the ocean and the land. The noise equivalent radiance (NER) corresponding to the instrument radiometric noise is compared with the radiometric resolution of signal digitization (1-count equivalent radiance). The best gain setting of OSMI for ocean monitoring is recommended. This analysis is considered to be useful for the OSMI mission and operation planning, the OSMI image data calibration, and users' understanding about OSMI image quality.

• Journal of KSNVE
• /
• v.1 no.2
• /
• pp.115-120
• /
• 1991

The impact hammer is extensively used in experimental modal analysis as a means to provide force over a broad range of frequencies. The hammer mass and the impact head are often changed to achieve a desired impact time duration with its corresponding input frequency spectrum, these mass changes affect the performance and sensitivity of the force transducer employed to measure the impact force. Both a mathematical model describing the effects of impact head and hammer mass on the performance of the force transducer and experimental verification of this model are presented here.

• Korean Journal of Remote Sensing
• /
• v.16 no.4
• /
• pp.305-313
• /
• 2000

A vicarious calibration method was developed for the OSMI sensor calibration. Employing measured aerosol optical thickness by a sunphotometer and a sky radiometer and water leaving radiance by ship measurements as inputs, TOA (top of the atmosphere) radiance at each OSMI band was simulated in conjunction with a radiative transfer model (Rstar5b) by Nakajima and Tanaka (1988). As a case of examining the accuracy of this method, we simulated TOA radiance based on water leaving radiance measured at NASA/MOBY site and aerosol optical thickness estimated nearby at Lanai, and compared simulated results with SeaWiFS-estimated TOA radiances. The difference falls within about $\pm$5%, suggesting that OMSI sensor can be calibrated with the suggested accuracy. In order to apply this method for the OSMI sensor calibration, ground-based sun photometry and ship measurements were carried out off the east coast of Korean peninsula on May 31, 2000. Simulations of TOA radiance by using these measured data as input to the radiative transfer model show that there are substantial differences between simulated and OSMI-estimated radiances. Such a discrepancy appears to be mainly due to the cloud contamination because satellite image indicates optically thin clouds over the experimental area. Nevertheless results suggest that sensor calibration can be achieved within 5% uncertainty range if there are ground-based measurements of aerosol optical thickness, and water leaving radiances under clear-sky and optically thin atmospheric conditions.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.2
• /
• pp.451-454
• /
• 2011

In this paper, a wideband clock generator using novel Automatic frequency calibration(AFC) scheme is proposed. Wideband clock generator using AFC has the advantage of small VCO gain and wide frequency band. The conventional AFC compares whether the feedback frequency is faster or slower then the reference frequency. However, the proposed AFC can detect frequency difference between reference frequency with feedback frequency. So it can be reduced an operation time than conventional methods AFC. Conventional AFC goes to the initial code if the frequency step changed. This AFC, on the other hand, can a prior state code so it can approach a fast operation. In simulation results, the proposed clock generator is designed for DisplayPort using the CMOS ring-VCO. The VCO tuning range is 350MHz, and a VCO frequency is 270MHz. The lock time of clock generator is less then 3us at input reference frequency, 67.5MHz. The phase noise is -109dBC/Hz at 1MHz offset from the center frequency. and power consumption is 10.1mW at 1.8V supply and layout area is $0.384mm^2$.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.11
• /
• pp.36-43
• /
• 2015

A pixel-level readout circuit is studied for 2-dimensional microbolometer focal plane arrays (FPAs). A current mirroring injection (CMI) input circuit with 2-step current-mode bias suppression is proposed for a pixel-level architecture with high responsivity and long integration time. The proposed circuit has been designed using a $0.35-{\mu}m$ 2-poly 4-metal CMOS process for a $320{\times}240$ microbolometer array with a pixel size of $50{\mu}m{\times}50{\mu}m$. The proposed 2-step bias-current suppression has sufficiently low calibration error with wide calibration range, and the calibration range and error can be easily optimized by controlling some design parameters. Due to high responsivity and a long integration time of more than 1 ms, the noise equivalent temperature difference (NETD) of the proposed circuit can be improved to 26 mK, which is much better than that of the conventional circuits, 67 mK.

• Journal of Sensor Science and Technology
• /
• v.5 no.3
• /
• pp.9-16
• /
• 1996

This paper deals with the capacitive voltage divider which can measure a transient voltages generated by operating a high voltage impulse generator. The transient voltage measuring system using the capacitive electric field sensor consists of the planar-type electric field sensor having a fast response characteristic and the wide-bandwidth voltage follower, and the input impedance of which is extremely high, about $10^{12}{\Omega}$. In order to analyze the response characteristics to a step input, the newly developed calibration method is proposed, and the error of voltage dividing ratio associated with set-up condition is investigated. Also the optimal set-up condition that is to be maintained within the range of 0.5 % is taken. From the calibration experiment, the frequency bandwidth of the transient voltage measuring system whose response time to a step input is about 15.8 ns, is from 6.37 Hz to 27.3 MHz. Therefore it is possible to measure the commercial frequency voltages as well as the transient over voltages without signal distortions.