• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.505-506
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• 2006

In this paper, the linearization technique for CMOS low-noise amplifier (LNA) using the derivative superposition method through the multiple gated transistors configuration is presented. LNA based on 0.13um RF CMOS process has been implemented with a modified cascode configuration using multiple gated common source transistors to fulfill a high linearity. Compared with a conventional cascode type LNA, the third order input intercept point (IIP3) per DC power consumption (IIP3/DC) is improved by 3.85 dB. The LNA achieved 2.5-dBm IIP3 with 13.4-dB gain, 3.6 dB NF at 2.4 GHz consuming 8.56 mA from a 1.5-V supply.

• Fashion & Textile Research Journal
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• v.7 no.5
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• pp.553-559
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• 2005

Hand characteristics related with structural properties of fabrics have something to do with mechanical properties of fabric. In this study, the mechanical properties and hand characteristics have been analyzed according to fabric structural parameters such as the weave structure and the linear density of weft of cotton fabric. Mechanical properties have been used by KES-FB system which measures hand characteristics and mechanical properties of fabric. Linear density of weft, tensile, bending, and shear properties are decreasing with increasing weft linear density, and there is no considerable effects on compression and surface properties. In case of formability with weft linear density, B/W, 2HG/G, 2HB/B, 2HB/W, $\sqrt[3]{B/W}$, $\sqrt{2HB/W}$, W/T except MMD/SMD, WC/T, and WC/W have been effected. There is a high correlation between the crimp, tightness, hand, formability and mechanical properties specially tensile linearity, bending, shear, and compression properties. The weft crimp influences the bending rigidity, shear properties, and the tightness which have effects on the tensile linearity, bending, shear, compression properties, hand, and formability.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.363-372
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• 2005

This paper presents an improved sensorless vector control system for high performance induction motor drives fed by a matrix converter with non-linearity compensation. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching devices is corrected by a new matrix converter model. A Reduced Order Extended Luenberger Observer (ROELO) is employed to bring better response in the whole speed operation range and a method to select the observer gain is presented. Experimental results are shown to illustrate the performance of the proposed system.

• Korean Journal of Food Science and Technology
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• v.53 no.6
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• pp.682-687
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• 2021

The purpose of this study was to validate a high-performance liquid chromatography (HPLC) method for the quantitative analysis of quercetin in various foods. The method was based on HPLC-UV (360 nm). The method was validated using candy, beverage, and sausage which were tested for specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy, and the measurement uncertainty was assessed. Matrix-matched calibration was also applied. The calibration curves (0.5-50 mg/L) showed good linearity (r²≥0.9998). LOD and LOQ ranged from 0.15 to 0.31 mg/kg and from 0.44 to 0.93 mg/kg, respectively. The average accuracy and precision at 0.5, 2.5, and 10 mg/kg ranged from 84.3 to 102.0% and 0.7 to 3.0 relative standard deviation (RSD%), respectively. This study confirmed the applicability of the proposed method by applying it to commercial products, such as teas and beverages. Thus, the proposed analytical method is suitable for quantifying quercetin in various foods.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.100-100
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• 2019

This study attempted to establish a High Performance Liquid Chromatography (HPLC) analysis method for the determination of (-)-epicatechin gallate as a part of the quality control for the development of functional cosmetic materials from Penthorum chinense Pursh extracts. HPLC was performed on a Unison US-C18 column ($4.6{\times}250mm$, $5{\mu}m$) with a gradient elution of 0.05% (v/v) trifluoroacetic acid (TFA) and methyl alcohol at a flow rate of 1.0 mL/min at $30^{\circ}C$. The analyte was detected at 280 nm. The HPLC method was performed in accordance with the International Conference on Harmonization (ICH) guideline (version 4, 2005) of analytical procedures with respect to specificity, precision, accuracy, and linearity. The limits of detection and quantitation were 0.11 and 0.33 mg/mL, respectively. Calibration curves showed good linearity (r2 > 0.9999), and the precision of analysis was satisfied (less than 0.6%). Recoveries of quantified compounds ranged from 99.51 to 101.92%. This result indicates that the established HPLC method is very useful for the determination of marker compound in P. chinense Pursh extracts.

• Korean Journal of Pharmacognosy
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• v.50 no.3
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• pp.226-231
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• 2019

Prunus yedoensis Matsum. (Rosaceae) has been used for cough, urticaria, pruritus, dermatitis, asthma and relaxation in traditional Korean medicine. In this study, naringenin, sakuranetin and prunetin were isolated from the barks of P. yedoensis and quantification were performed by using high performance liquid chromatography (HPLC) method with diode array detector. The structures of naringenin and sakuranetin, prunetin were identified NMR spectroscopic data analysis. The content of each compound was analyzed by HPLC and the analytical method was validated through linearity, precision, accuracy and specificity test. The result showed that calibration curves of three compounds naringenin, sakuranetin and prunetin indicated great linearity with a correlation coefficient ($R^2$) of 1.00, 1.00 and 0.99. Intra and inter day measurement accuracy of the three compounds ranged from 92.70 ~ 112.70%, and showed precision was less than 3%. Therefore, the content analysis showed that naringenin ($0.132{\pm}0.016%$), sakuranetin ($0.108{\pm}0.023%$), and prunetin ($0.059{\pm}0.014%$).

• Korean Journal of Pharmacognosy
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• v.50 no.1
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• pp.59-64
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• 2019

Cudrania tricuspidata Bureau (Moraceae) has been used for physical weakness, impotence and insomnia in traditional Korean medicine. In this study, cudratricusxanthone A and cudraxanthone D were isolated from roots of C. tricuspidata and quantification were achieved by using high performance liquid chromatography (HPLC) method with diode array detector. The isolated compound was identified by NMR analysis and HPLC method was validated by linearity, precision and specificity test. The results showed that calibration curves of two compounds indicated great linearity with a correlation coefficient ($R^2$) of 0.9976 and 0.9995. The limits of detection (LOD) for cudratricusxanthone A and cudraxanthone D were 1.15, $0.11{\mu}g/ml$. Intra-day precision of cudratricusxanthone A and cudraxanthone D were 0.32~1.99%, 0.09~3.32% and inter-day precision were 0.59~2.40%, 0.28~1.55% RSD (%) values, respectively. The specificity was confirmed by chromatograph and quantitative contents of cudratricusxanthone A and cudraxanthone D were $0.46{\pm}0.02%$ and $1.53{\pm}0.06%$. Therefore, this study can be used as a basic research data for the quantitative analysis of derived compounds from roots of C. tricuspidata.

• Korean Journal of Veterinary Service
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• v.45 no.3
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• pp.237-242
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• 2022

The simultaneous analysis of mycotoxins using LC-MS/MS, a food official analysis method, was applied with compound feed for pets with high consumer preferences. In this study, the linearity of all calibration curves showed good linearity of 0.99 or more. and both the accuracy (recovery rate) and precision (repeatability) criteria of the concentration range for each mycotoxin in the National Agricultural Products Quality Management Service's Validation and Verification Guidelines were met. And as a result of analyzing FAPAS QCM in the same way, it was assesed that the z-scores of Aflatoxin B₁, Ochratoxin A, Zearalenone, and Fumonisin B₁, were within ±2 range. This study showed that the application of the food official analysis method to compound feed for pets is suitable.

• Analytical Science and Technology
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• v.36 no.2
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• pp.89-98
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• 2023

Analytical methods for detecting atranol, chloroatranol, evernic acid, (+)-usnic acid, and atranorin in sanitary napkins and mouthwashes were developed using ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). UHPLC-MS/MS conditions were optimized for rapid, sensitive, and simultaneous analysis of the five allergenic compounds. The methods were validated by assessing their specificity, matrix effects, limit of detection (LOD), limit of quantification (LOQ), linearity, accuracy, and precision. Good linearity was achieved with a determination coefficient of ≥0.99. The LOD and LOQ were 2.1-9.8 and 6.4-29.6 ng/g for sanitary napkins and 0.29-0.48 and 0.87-1.45 ng/mL for mouthwashes, respectively. The accuracy and precision were within an acceptable range according to the criteria reported in the European SANTE/11813/2017 guidelines (70-120 % recovery, <20 % relative standard deviation). Therefore, these methods can be used to analyze atranol, chloroatranol, evernic acid, (+)-usnic acid, and atranorin in sanitary napkins and mouthwashes.

• Current Optics and Photonics
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• v.7 no.5
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• pp.504-510
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• 2023

An optical fiber dislocation fusion humidity sensor coated with graphene quantum dots is investigated. A Mach-Zehnder interferometer is fabricated with three dislocated single-mode fibers with graphene quantum dots coating humidity-sensitive materials. Humidity response experiments showed a good linear response and high sensitivity with easy fabrication and low-cost materials. From 22% to 98% RH, the humidity response sensitivity of the sensor is 0.24 dB/% RH, with 0.9825 linearity. To investigate the cross-response of humidity and temperature, temperature response experiments are conducted. From 30 ℃ to 70 ℃, the results showed 0.02 dB/℃ sensitivity and 0.9824 linearity. The humidity response experimental curve is compared with the temperature experimental curve. The big difference between humidity sensitivity and temperature sensitivity is very helpful to solve the cross-response of humidity and temperature. The influence of temperature fluctuations in humidity measurements is not obvious.