• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.11 no.1
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• pp.10-15
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• 2012

Ultra wideband (UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geo-location, and other applications. The energy of UWB signal is extremely spread from near DC (Direct Current) to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional wireless systems sharing the frequency bands such as broadcasting system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely an orthogonal frequency division multiplex UWB source and an impulse radio UWB source, to a broadcasting transmission system. The S/N ratio degradation of broadcasting system is presented. From these experimental results, we show that in all practical cases UWB system can be coexisted 35m distance in-band broadcasting network.

• Journal of the Institute of Convergence Signal Processing
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• v.4 no.2
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• pp.61-69
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• 2003

In this paper, we developed the U parameter test system which inspects the property of DC parameter for semiconductor products. The developed system is interfaced by IBM-PC. It is consisted of CPLD part, ADC (Analogue to Digital Converter), DAC (Digital to Analogue Converter), voltage/current source, variable resistor and measurement part. In the proposed system, we have designed the constant voltage source and the constant current source in a part. The CPLD part is designed by VHBL, which it generates the control and converts the serial data to parallel data. The proposed system has two test channels and it operates VFCS mode and CFVS mode. The range of test voltage is from 0[V] to 100[V], and the range of test current is from 0[mA] to 100[mA)]. The diode is tested. The test results have a good performance.

• Transactions on Electrical and Electronic Materials
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• v.2 no.1
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• pp.16-21
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• 2001

A new technique to measure low level capacitance variations of a gyroscope is proposed. It is based on the improved CVC(capacitance to voltage converter) biased by a d.c. current source and the peak detector without any low pass filter. This setup of the measurement system makes it possible to provide higher speed of measurement and wide operation range. The d,c, drift of the conventional CVC and stray capacitances are automatically compensated. Key parameters that affect the performance of the measurement system are illustrated and computer simulation results are presented. The demonstrated measurement system for micromachined gyroscope applications shows a linearity of 0.99972 and a resolution of 0.67fF from 10 fF to 120 fF at 10 kHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.864-867
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• 2003

Since the development of semiconductors, various related research has been conducted. During research, silicon diodes have been commonly used because of their simplicity and low cost in the manufacturing process. This research deals with p-n junction threshold voltages from silicon diodes due to transport current at a cryogenic temperature. At a cryogenic temperature(77K) we could get minimum current which junction threshold voltage becomes constant. This is experimented on GPIB communication and it consist of programmable current source, multimeter which gauge the threshold voltage in a very low temperature caused by transport current from 5nA to 1mA and $LN_2$(77K) for coolant. This experiment is programmed all process using Measurement studio(Lab window) tool.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.10
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• pp.687-692
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• 1999

A new technique to measure low level capacitance variations of the gyroscope is proposed and verified by computer simulation. It is based on the new CV(capacitance-voltage) converter circuit biased by dc current source and the peak detector without low pass filter. The CV converter biased by dc current source provides good signal-to-noise ratio and this setup of the detection circuitry without low pass filter makes it possible to provide short settling time, that is, higher speed of measurement and wide operation range if only a few parameters are adjusted. The key parameters that affect the performance of the detection circuitry are illustrated and computer simulation results are presented. The demonstrated detection circuitry shows linear response from 10 fF to 130 fF at 10 kHz and shows good linearity.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.58-60
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• 1998

The precise measurement of consumed power during the given time is very important in the energy management aspect. Up to days, induction watthour meter has been designed for use in the alternating circuits in which the voltage and current are essentially sinusoidal. The use of switching elements in power system causes the current or voltage involving harmonics. Therefore the registration error is caused by harmonics in the equipment for measuring power. This paper presents the registration error of the induction watthour meter in the presence of harmonic distortion. The accuracy of a watthour meter on loads in which the input source is not sinusoidal is investigated. And the effects of individual harmonic are reported by experiment.

• English Language & Literature Teaching
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• v.12 no.1
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• pp.221-238
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• 2006

This study investigates the reliability of plagiarism measurement in the ESL essay writing context. The current study aims to address the answers to the following research questions: 1) How does plagiarism measurement affect test reliability in a psychometric view? and 2) how do raters conceive the plagiarism in their analytic scoring? This study uses the mixed-methodology that crosses quantitative-qualitative techniques. Thirty eight international students took an ESL placement writing test offered by the University of Illinois. Two native expert raters rated students' essays in terms of 5 analytic features (organization, content, language use, source use, plagiarism) and made a holistic score using a scoring benchmark. For research question 1, the current study, using G-theory and Multi-facet Rasch model, found that plagiarism measurement threatened test reliability. For research question 2, two native raters and one non-native rater in their email correspondences responded that plagiarism was not a valid analytic area to be measured in a large-scale writing test. They viewed the plagiarism as a difficult measurement are. In conclusion, this study proposes that a systematic training program for avoiding plagiarism should be given to students. In addition, this study suggested that plagiarism is measured reliably in the small-scale classroom test.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.339-347
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• 2023

Dissolved organic matter (DOM) is a key component in the biogeochemical cycling in freshwater ecosystem. However, it has been rarely explored, particularly complex river watershed dominated by natural and anthropogenic sources, such as various effluent facility and livestock. The current research developed a new analytical method for TOC/TN (Total Organic Carbon/Total Nitrogen) stable isotope ratio, and distinguish DOM source using stable isotope value (δ¹³C-DOC) and spectroscopic indices (fluorescence index [FI] and biological index [BIX]). The TOC/TN-IR/MS analytical system was optimized and precision and accuracy were secured using two international standards (IAEA-600 Caffein, IAEA-CH-6 Sucrose). As a result of controlling the instrumental conditions to enable TOC stable isotope analysis even in low-concentration environmental samples (<1 mgC L^-1), the minimum detection limit was improved. The 12 potential DOM source were collected from watershed, which includes top-soils, groundwater, plant group (fallen leaves, riparian plants, suspended algae) and effluent group (pig and cow livestock, agricultural land, urban, industry facility, swine facility and wastewater treatment facilities). As a result of comparing characteristics between 12 sources using spectroscopic indices and δ¹³C-DOC values, it were divided into four groups according to their characteristics as a respective DOM sources. The current study established the TOC/TN stable isotope analyses system for the first time in Korea, and found that spectroscopic indices and δ¹³C-DOC are very useful tool to trace the origin of organic matter in the aquatic environments through library database.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.63-68
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• 2003

Scanning electron microscopy (SEM) has been used as a surface measurement instrument and a tool for lithography in semiconductor process due to its high density localized beam. For those purposes, however, the maximum current of SEM Is less than 100pA, which is not enough fo material processing. In this paper SEM was modified to increase the amount of current reaching a specimen from gun part where current is generated, the possibility of applying SEM to material processing, especially microjoining, was investigated. The maximum current of SEM after modifications was measured up to 10$\mu$A, which is about 10$^{5}$ times greater than before modifications. Through experiments such as eutectic solder wetting on thin 304 stainless steel foil and microjoining of 10$\mu$m thick 304 stainless steel, the intensity of electron beam of SEM proved to be great enough fur material processing as heat source. And a tight jig system was found necessary to hold materials close enough fur successful microloining.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.373-378
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• 2008

In this paper, an Active Power Filter (APF) is implemented using a dSPACE DS1104 processor to compensate harmonics and reactive power produced by nonlinear load. The reference source current is computed based on the measurement of harmonics in the supply voltage and load current. A hysteresis based current controller has been implemented in a DSP processor for injecting the compensating current into the power system, so that APF allows suppression of the harmonics and reactive power component of load current, resulting in a supply current that is purely sinusoidal. Simulation and experimental results of the proposed APF to meet the IEEE-519 standards are presented.