• JSTS:Journal of Semiconductor Technology and Science
• /
• 제3권4호
• /
• pp.211-216
• /
• 2003

This work describes a 3 V 12b 100 MS/s CMOS digital-to-analog converter (DAC) for high-speed communication system applications. The proposed DAC is composed of a unit current-cell matrix for 8 MSBs and a binary-weighted array for 4 LSBs, trading-off linearity, power consumption, chip area, and glitch energy with this process. The low-glitch switch driving circuits are employed to improve linearity and dynamic performance. Current sources of the DAC are laid out separately from the current-cell switch matrix core block to reduce transient noise coupling. The prototype DAC is implemented in a 0.35 um n-well single-poly quad-metal CMOS technology and the measured DNL and INL are within ${\pm}0.75$ LSB and ${\pm}1.73$ LSB at 12b, respectively. The spurious-free dynamic range (SFDR) is 64 dB at 100 MS/s with a 10 MHz input sinewave. The DAC dissipates 91 mW at 3 V and occupies the active die area of $2.2{\;}mm{\;}{\times}{\;}2.0{\;}mm$

• 분석과학
• /
• 제30권5호
• /
• pp.221-225
• /
• 2017

Thioctic acid is a vitamin-like antioxidant which is prepared as tablets and injection. The Korean Pharmacopoeia (KP XI) contains monograph for the quality control of raw thioctic acid using ultra-violet visible spectrophotometry and its formulations using high performance liquid chromatography (HPLC). In British Pharmacopoeia 2013 (BP2013), another HPLC method is used for the assay test of thioctic acid material. For the international harmonization, we present an HPLC method for quantitation of thioctic acid in both raw material and tablets. Method validation was performed to determine linearity, precision, accuracy, system suitability, and robustness. The linearity of calibration curves in the desired concentration range was high ($r^2=0.9995$), while the RSDs for intra- and inter-day precision were 0.93 ~ 1.26 % and 1.40 ~ 1.76 %, respectively. Accuracies ranged from 98.13-100.00 %. Since the system suitability, intermediate-precision and robustness of the assay were satisfactory, this method will be a valuable addition to the Korean Pharmacopoeia (KP XI).

• 한국통신학회논문지
• /
• 제39A권10호
• /
• pp.613-615
• /
• 2014

본 논문에서는 TVWS(TV white space)용 광대역 고선형 전력증폭기의 설계 및 구현에 대해서 기술한다. TVWS용 전력증폭기는 기존의 방송시스템에 미치는 영향을 최소화하기 위해서 방사전력 및 스펙트럼 마스크를 엄격하게 제한해야 한다. 구현한 전력증폭기는 460 ~ 698MHz 대역에서 동작하며, $24.7{\pm}1dB$의 이득, -25dB 이하의 입력반사계수, -7.82dB 이하의 출력반사계수 그리고 22.2dBm 출력전력에서 -57.7dBc의 선형성을 갖는다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제13권2호
• /
• pp.127-138
• /
• 2013

The impact of Empty Space layer in the channel region of a Double Gate (i.e. ESDG) MOSFET has been studied, by monitoring the DC, RF as well as the digital performance of the device using ATLAS 3D device simulator. The influence of temperature variation on different devices, i.e. Double Gate incorporating Empty Space (ESDG), Empty Space in Silicon (ESS), Double Gate (DG) and Bulk MOSFET has also been studied. The electrical performance of scaled ESDG MOSFET shows high immunity against Short Channel Effects (SCEs) and temperature variations. The present work also includes the linearity performance study in terms of $VIP_2$ and $VIP_3$. The proper bias point to get the higher linearity along with the higher transconductance and device gain has also been discussed.

• 한국위성정보통신학회논문지
• /
• 제9권2호
• /
• pp.7-11
• /
• 2014

본 논문에서는 $0.5{\mu}m$ p-HEMT 공정을 이용한 MMIC 주파수 혼합기를 설계하였다. 본 주파수 혼합기는 Local 신호전력이 -4 ~ 4 dBm에서 유사한 성능을 갖도록 설계하여 local 신호의 변화에 따른 변환 성능이나 선형 성능이 일정하게 유지 되도록 하였다. 이와 같은 특성을 갖도록 하기 위해 새로운 형태의 FET를 이용한 피드백 회로를 구성하여, LO신호전력의 변화에 따른 성능 변화를 최소화 하였으며 넓은 주파수 대역에서 사용 할 수 있는 MMIC 주파수 혼합기 성능을 얻었다. 설계결과 LO신호전력이 -4 ~ 4dBm일 때, 0.5 ~ 2.6GHz의 주파수 범위에서 변환손실이 6 dB에 IIP3가 30 dBm 이상의 우수한 성능을 갖는 설계 결과를 얻었다.

• Natural Product Sciences
• /
• 제22권2호
• /
• pp.77-81
• /
• 2016

A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of three antibacterial flavonoids, artocarpanone, artocarpin, and cycloartocarpin in ethyl acetate extracts from Artocarpus heterophyllus heartwoods. Separation was achieved using a TSK-gel ODS-80Tm column ($5{\mu}m$, $4.6{\times}150mm$) at $25^{\circ}C$ with a gradient elution system of methanol and water as follows: 0-8 min, 60:40; 8-27 min, 80:20; 27-35 min, 60:40, v/v, at a flow rate of 1 mL/min, and a quantitative UV detection at 285 nm. The method was validated by measuring the key parameters, including specificity, linearity, sensitivity, accuracy, repeatability and reproducibility. A high degree of specificity and sensitivity was achieved. The calibration curves for all three flavonoids showed good linearity with a coefficient of determinations ($R^2$) of ${\geq}0.9995$. The recoveries of the method were from 98-104%, with good reproducibility and repeatability (RSD values of less than 2%) were also achieved. Ethyl acetate was the best solvent for extraction of these three flavonoids using the heat reflux conditions for 1 h. This optimized sample preparation and HPLC method can be practically used for a routine standardization process of the extracts from the A. heterophyllus heartwoods.

• Advances in concrete construction
• /
• 제11권3호
• /
• pp.261-270
• /
• 2021

In this study, a new understanding is presented on the microcracking behavior of high strength concrete (HSC) with steel fiber addition having prior compressive loading history. Microcracking behavior at critical stress (σcr) region, using seven fiber addition volume of 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, and 2.0% was evaluated, at two aspect ratios (60 and 75). The specimens were loaded up to a specified compressive stress levels (0.70fc-0.96fc), and subsequently subjected to split tensile tests. This was followed by microscopic analyses afterwards. Four compressive stress levels as percentage of fc were selected according to the linearity end point based on stress-time (σ-t) diagram under uniaxial compression. It was seen that pre-compression has an effect on the linearity end point as well as fiber addition where it lies within 85-91% of fc. Tensile strength gain was observed in some cases with respect to the 'maiden' tensile strength as oppose to tensile strength loss due to the fiber addition with teething effect. Aggregate cracking was the dominant failure mode instead of bond cracks due to improved matrix quality. The presence of the steel fiber improved the extensive failure pattern of cracks where it changes from 'macrocracks' to a branched network of microcracks especially at higher fiber dosages. The applied pre-compression resulted in hardening effect, but the cracking process is similar to that in concrete without fiber addition.

• 분석과학
• /
• 제36권6호
• /
• pp.281-290
• /
• 2023

Zidovudine is an antiretroviral agent prescribed for the prevention and treatment of human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). It is typically recommended to be used in combination with other antiretroviral drugs. Zidovudine has the potential to generate N-nitrosodimethylamine (NDMA) in the presence of dimethylamine and nitrite salt under acidic reaction conditions during the drug manufacturing process. NDMA is a potent human carcinogen that may be detected in drug substances or drug products. An analytical method was developed to determine NDMA in pharmaceuticals including zidovudine using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The analysis involved reversed-phase chromatography on a Kinetex F5 column with a mobile phase comprising water-acetonitrile mixtures. The detection of positively charged ions was conducted using atmospheric pressure chemical ionization (APCI). The calibration curve demonstrated excellent linearity (r = 0.9997) across the range of 1-50 ng/mL with a highly sensitive limit of detection (LOD) at 0.3 ng/mL. The developed method underwent thorough validation for specificity, linearity, accuracy, precision, robustness, and system suitability. This sensitive and specific analytical method was applied for detecting NDMA in zidovudine drug substance and its formulation currently available in the market, indicating its suitability for drug quality management purposes.

• 한국축산식품학회지
• /
• 제43권6호
• /
• pp.949-960
• /
• 2023

This research aimed to validate a high-performance liquid chromatography method for the quantitative determination of bixin and norbixin in various foods. The Diode Array Detector (495 nm) technique was used. Method was validated for specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy, and the measurement uncertainty was assessed. The calibration curve showed excellent linearity (r²≥0.9999) over the tested concentration range of 0.2-25 mg/L. The LOD and LOQ were 0.03-0.11 and 0.02-0.05 mg/L for bixin and norbixin, respectively. The intra-and inter-day accuracies and precisions were 88.0±1.3-97.0±0.5% and 0.2%-2.6% relative SD (RSD) for bixin and 88.2±0.8-105.8±0.8% and 0.3%-2.7% RSD for norbixin, respectively. Inter-laboratory validation for accuracy and precision was conducted in three laboratories, and these results all met the AOAC guidelines. In addition, the relative expanded uncertainty (<22%) satisfied the CODEX recommendation. Furthermore, products distributed in Korea were monitored for annatto extracts using the proposed method to demonstrate its application. The developed analytical method is reliable for quantifying bixin and norbixin in various foods.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
• /
• pp.9-11
• /
• 2000

To increase the device linearities and the breakdown-voltages of FETs, Al$\sub$0.25/ Ga$\sub$0.75/AS / In$\sub$0.25/Ga$\sub$0.75/As / Partially doped channel FET(DCFET) structures are proposed. The metal- insulator -semiconductor (MIS) like structures show the high gate-drain breakdown voltage(-20 V) and high linearities. The devices showed the small ripple of the current cut-off frequency and the power cut-off frequency over the wide bias range.