• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.5
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• pp.480-485
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• 2004

In this paper, a new predistortion linearizing method using frequency up-conversion operation of mixer is proposed. This linearizing method doesn't require any additional signal sources in spite of frequency up-conversion mixing operation. This method extracts the 2nd low frequency intermodulation distortion signal from input signals and uses the extracted 2nd low frequency intermodulation distortion signal as mixing signal source. To show validation of the proposed predistortion method, we made K-PCS power amplifier. On 2-tone signals amplification process, the (C/I) ratio of amplifier is improved 26 ㏈ (@Po=22 ㏈m/tone), where two tones are 1.8544 ㎓ and 1.8556 ㎓, respectively. And (C/I) ratio is improved more than to 20 ㏈ for 17 ㏈ output signal dynamic range. On IS-95A CDMA 1FA amplification process, the improvements of adjacent channel power ratio(ACPR) are 10.8 ㏈ and 6.4 ㏈ at ${\pm}$885 ㎑ and ${\pm}$1.25 ㎒ offset points, respectively.

• International Journal of Highway Engineering
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• v.17 no.1
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• pp.91-98
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• 2015

PURPOSES : Although signalized intersections have been considered the best way to control traffic volume in urban areas for several decades, roundabouts are currently being discussed as an alternative way to control traffic volume, especially when traffic is light. Because a roundabout's efficiency depends on the load geometry as well as the traffic volume, design guidelines for roundabouts are recommended only if the incoming traffic volume is very low. It is rare to substitute a roundabout for an existing signalized intersection in urban areas. This study aims to estimate the benefits from the transformation of an existing signalized intersection into a roundabout in an urban area. When there is a more moderate volume of traffic, roundabouts can be effectively used by optimizing signals located at an approaching roadway. METHODS : The methodologies of this paper are as follows: First, a signalized intersection was analyzed to determine the traffic characteristics. Second, the signalized intersection was transformed into a roundabout using VISSIM microscopic traffic simulation. Then, we estimated and analyzed the effects and the performance of the roundabout. In addition, we adjusted a method to improve the benefits of the transformation via the optimization of signals located at an approaching road to control the incoming traffic volume. RESULTS : The results of this research are as follows: The signal-optimized roundabout improved delays compared with the signalized intersection during the morning peak hour, non-peak hour, and evening peak hour by 1.78%, 12.45%, and 12.72%, respectively. CONCLUSIONS : According to the simulation results of each scenarios, the signal-optimized roundabout had less delay time than the signalized intersection. If optimized signal control algorithms are installed in roundabouts in the future, this will lead to more efficient traffic management.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.536-541
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• 2001

A high resolution digital cinematic Particle Image Velocimetry(PIV) has been developed. The system consists of a high speed CCD camera, a continuous Ar-ion laser and a computer with camera controller. To improve the spatial resolution, we adopt a Recursive Technique for velocity interrogation. At first, we obtain a velocity vector for a larger interrogation window size based on the conventional two-frame cross-correlation PIV analysis using the FFT algorithm. Based on the knowing velocity information, more spatially resolved velocity vectors are obtained in the next iteration step with smaller interrogation windows. The correct velocity vector at the first step is found to be critical, so we apply a Multiple Correlation Validation(MCV) technique in order to decrease the spurious vectors. The MCV technique turns out to improve SNR(Signal to Noise Ratio) of the correlation table. The developed cinematic PIV method has been applied to the measurement of the unsteady flow characteristics of a Rushton turbine mixer. A total of 3,245 instantaneous velocity vectors were successfully obtained with 4 ms time resolution. The acquired spatial resolution corresponds the performance of the conventional high resolution digital PIV system using a $1K{\times}1K$ CCD camera.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.1038-1046
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• 2008

This study was carried out to develop a small-sized biosensor based on surface plasmon resonance (SPR) for the rapid identification of insecticide residues for food safety. The SPR biosensor module consists of a single 770 nm-light emitting diodes (LED) light source, several optical lenses for transferring light, a hemisphere sensor chip, photo detector, A/D converter, power source, and software for signal processing using a computer. Except for the computer, the size and weight of the sensor module are 150 (L)$\times$70 (W)$\times$120 (H) mm and 828 g, respectively. Validation and application procedures were designed to assess refractive index analysis, affinity properties, sensitivity, linearity, limits of detection, and robustness which includes an analysis of baseline stability and reproducibility of ligand immobilization using carbamate (carbofuran and carbaryl) and organophosphate (cadusafos, ethoprofos, and chlorpyrifos) insecticide residues. With direct binding analysis, insecticide residues were detected at less than the minimum 0.01 ppm and analyzed in less than 100 sec with a good linear relationship. Based on these results, we find that the binding interaction with active target groups in enzymes using the miniaturized SPR biosensor could detect low concentrations which satisfy the maximum residue limits for pesticide tolerance in Korea, Japan, and the USA.

• Molecular & Cellular Toxicology
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• v.1 no.1
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• pp.52-61
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• 2005

Transcript profiling is a particularly valuable tool in the field of steroid receptor biology, as these receptors are ligand-activated transcription factors and therefore exert their initial effects through altering gene expression in responsive cells. Also, an awareness of endocrine disrupting chemicals (EDCs) and their potential screening methods to identify endocrine activity have been increased. Here we developed an in-house cDNA microarray, named KISTCHIP-400 ver. 1.0, with 416 clones, based on public database and research papers. These clones contained estrogen, androgen, thyroid hormone & receptors, sex hormone signal transduction & regulation, c-fos, c-myc, ps2 gene, metabolism related genes etc. Also, to validate the KISTCHIP-400 ver. 1.0, we investigated gene expression profiles with reference hormones, $10^{8}\;M\;17{\beta}-estradiol,\;10^{-7}\;M\;testosterone\;and\;10^{-7}\;M$ progesterone in MCF-7 cell line. As the results, gene expression profiles of three reference hormones were distinguished from each other with significant and identified 33 $17{\beta}-estradiol$ responsive genes. This study is in first step of validation for KISTCHIP-400 ver. 1.0, as following step transcriptional profile analysis on not only low concentrations of EDCs but suspected EDCs using KISTCHIP-400 ver. 1.0 is processing. Our results indicate that the developed microarray may be a useful laboratory tool for screening EDCs and elucidating endocrine disrupting mechanism.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.180-180
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• 2003

Transcript profiling is a particularly valuable tool in the field of steroid receptor biology, as these receptors are ligand-activated transcription factors and therefore exert their initial effects through altering gene expression in responsive cells. Also, an increased awareness of endocrine disrupting chemicals (EBCs) and their potential to affect wildlife and humans has produced a demand for practical screening methods to identify endocrine activity. Here we developed an in-house cDNA microarray, named KISTCHIP-400, with 401 clones, hormone related genes, factors, and ESTs, based on public database and research papers. Theses clones contained estrogen, androgen, thyroid hormone St receptors, sex hormone signal transduction ＆ regulation, c-fos, c-myc, ps2 gene, metabolism related genes etc. And to validate the KISTCHIP-400, we investigated gene expression profiles with reference hormones, 10$\^$-8/ M 17be1a-estradiol, 10$\^$-7/ M testosterone, 10$\^$-7/ M progesterone, and thyroxin in MCF-7 cell line. Although it is in first step of validation, low doses and combinations of EDCs need to be tested. Our preliminary results that indicate the developed microarray may be a useful laboratory tool for screening EDCs and elucidating endocrine disrupting mechanism.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.54.2-54.2
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• 2016

We present a machine learning approach to estimating stellar atmospheric parameters, effective temperature (Teff), surface gravity (log g), and metallicity ([Fe/H]) for stars observed during the course of the Sloan Digital Sky Survey (SDSS). For training a neural network, we randomly sampled the SDSS data with stellar parameters available from SEGUE Stellar Parameter Pipeline (SSPP) to cover the parameter space as wide as possible. We selected stars that are not included in the training sample as validation sample to determine the accuracy and precision of each parameter. We also divided the training and validation samples into four groups that cover signal-to-noise ratio (S/N) of 10-20, 20-30, 30-50, and over 50 to assess the effect of S/N on the parameter estimation. We find from the comparison of the network-driven parameters with the SSPP ones the range of the uncertainties of 73~123 K in Teff, 0.18~0.42 dex in log g, and 0.12~0.25 dex in [Fe/H], respectively, depending on the S/N range adopted. We conclude that these precisions are high enough to study the chemical and kinematic properties of the Galactic disk and halo stars, and we will attempt to apply this technique to Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), which plans to obtain about 8 million stellar spectra, in order to estimate stellar parameters.

• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.413-423
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• 2008

The template matching method is used as a simple method to track objects or patterns that we want to search for in the input image data from image sensors. It recognizes a segment with the highest correlation as a target. The concept of this method is similar to that of SNF (Strongest Neighbor Filter) that regards the measurement with the highest signal intensity as target-originated among other measurements. The SNF assumes that the strongest neighbor (SN) measurement in the validation gate originates from the target of interest and the SNF utilizes the SN in the update step of a standard Kalman filter (SKF). The SNF is widely used along with the nearest neighbor filter (NNF), due to computational simplicity in spite of its inconsistency of handling the SN as if it is the true target. Probabilistic Strongest Neighbor Filter for m validated measurements (PSNF-m) accounts for the probability that the SN in the validation gate originates from the target while the SNF assumes at any time that the SN measurement is target-originated. It is known that the PSNF-m is superior to the SNF in performance at a cost of increased computational load. In this paper, we suggest an image tracking algorithm that combines the template matching and the PSNF-m to estimate the states of a tracked target. Computer simulation results are included to demonstrate the performance of the proposed algorithm in comparison with other algorithms.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1535-1542
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• 2001

A high resolution digital cinematic Particle Image Velocimetry(PIV) has been developed. The system consists of a high speed CCD camera, a continuous Ar-ion laser and a computer with camera controller. To improve the spatial resolution, we adopt a Recursive Technique for velocity interrogation. At first, we obtain a velocity vector fur a larger interrogation window size based on the conventional two-frame cross-correlation PIV analysis using the FFT algorithm. Based on the knowing velocity information, more spatially resolved velocity vectors are obtained in the next iteration step with smaller interrogation windows. When the correct velocity vector at the first step is found to be critical, a Multiple Correlation Validation(MCV) technique is applied to decrease the spurious vectors. The MCV technique turns out to improve SNR(Signal to Noise Ratio) of the correlation table. The developed cinematic PIV method has been applied to the measurement of the unsteady flow characteristics of a Rushton turbine mixer. A total of 3,245 instantaneous velocity vectors were successfully obtained with 4 ms time resolution. The acquired spatial resolution corresponds to the conventional high resolution digital PIV system using a 1K ${\times}$ 1K CCD camera.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.229-236
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• 2020

A crush switch assembly(CSA) connected to an impact fuze provides electrical signal for detonation of the loaded main charge when an impact with the target is detected. Because the CSA experiences continuous changes in flight environment such as changes in velocity, vibration, and stresses, it is necessary to accurately predict the behavior of the fuze to maintain functionality during flight and to detonate when necessary. In this paper, random vibration analysis for flight environment and impact analysis on target hit are performed using FEA. Then, high speed impact tests are performed with the original and scaled down models to ensure operation validation of the manufactured products. The test results are then compared with M&S results to verify the capability of currently modeled CSA.