• Journal of Positioning, Navigation, and Timing
• /
• 제8권3호
• /
• pp.95-105
• /
• 2019

A method that applies space-time adaptive signal processing (STAP) algorithm based on an array antenna consisting of multiple antenna elements has been known to be effective to remove wide-band jamming signals in GPS receivers. However, the occurrence of phase distortion in navigation signals has been a problem when navigation signals, from which jamming signals are removed using STAP, are supplied to global positioning system (GPS) receivers. This paper verified the navigation performance degradation as a result of phase distortion. To mitigate this phenomenon, this paper proposes a mode switching scheme, in which a bypass mode is adopted to make the best use of the tracking performance of receivers without performing signal processing when jamming signals are not present or weak, and a STAP mode is employed when jamming signals exceed the threshold value. In this paper, the mode switching scheme is proposed for two environments: when receivers are stationary, and when receivers are moving. This paper confirmed that the performance of position error improved because phase distortion could be excluded due to STAP if the bypass mode was adopted under a condition where the jamming signal power level was below the threshold value in an environment where receivers were stationary. However, this paper also observed that the navigation failed due to the instability of tracking performance of receivers due to phase distortion that occurred at the switching time, although the number of switching could be reduced dramatically by proposing a dual threshold scheme of on- and off-thresholds that switched a mode due to the array antenna characteristics of varying gains according to the jamming signal incident direction in an environment where receivers were moving. The analysis results verified that running the STAP algorithm at all times is more efficient than the mode switching, in terms of maintaining stable navigation and ensuring position error performance, to remove jamming signals in an environment where receivers were moving.

• 한국균학회지
• /
• 제13권4호
• /
• pp.235-241
• /
• 1985

본 연구는, catabolic repression시킨 효모세포를 완전배지와 최소배지에서 derepression시켜, 배양시기 및 인산 첨가농도(free, limited, sufficient)에 따른 5종의 다당류 합성변화를 조사하였다. 그리고 다당류 합성과 무기폴리인산 축적량 및 인지질 합성 사이의 상관지수를 구하여 합성시 관련되는 유의한 정도를 검정하였다. 그 결과, 최소배지에서 catabolic derepression시킨 효모세포가, 완전배지에서 derepression시킨 세포에 비하여, glycogen의 합성이 발리 그리고 많이 일어났고, acid soluble glycogen type이 주된 함량을 나타내었으며, alkali soluble glycogen은 당이 많이 소모된 24시간 배양 후에 소량 나타났다. 무기인산 첨가정도에 따라 total glycogen합성이 일정한 비율로 빨리 그리고 높게 일어났다. Glucan의 합성에는 ALPase 중 ALPase "C"가 관련할 것으로 추정되었다. Mannan은 ezponential phase초기와 정체기때, acid soluble 분획은 정체기때 최대함량을 나타내었다. Mannan 합성과 poly-P "C"축적량 사이의 상관지수는 0.866, mannan합성과 인지질 사이의 상관지수는 0.726으로 나타나 매우 유의하였다.

• Bulletin of the Korean Chemical Society
• /
• 제26권8호
• /
• pp.1246-1250
• /
• 2005

We have evaluated the hydroxyl group-solvent specific interactions by using a Lichrosorb RP18 stationary phase and by measuring the retention data of carefully selected solutes in 50/50, 60/40, 70/30, 80/20, and 90/10(v/v%) methanol/water eluents at 25, 30, 35, 40, 45, and 50 ${^{\circ}C}$. The selected solutes are 3 positional isomers of phenylpropanol, that is, 1-phenyl-1-propanol, 1-phenyl-2-propanol, and 3-phenyl-1-propanol. There exist clear discrepancies in ${\Delta}H^o$ (solute transfer enthalpy from the mobile to the stationary phase) and $T{\Delta}S^o$ (solute transfer entropy) among positional isomers. The difference in ${\Delta}H^o$ and $T{\Delta}S^o$ between secondary alcohols (1-phenyl-1-propanol and 1-phenyl-2-propanol)is negligible compared to the difference between the primary alcohol (1-phenyl-3-propanol) and secondary alcohols. The $T{\Delta}S^o$ values of 3-phenyl-1-propanol are close to those of butylbenzene while the $T{\Delta}S^o$ values of secondary alcohols are close to those of propylbenzene. The difference in ${\Delta}{\Delta}H^o$ (specific solute-mobile phase interaction enthalpy) between the primary alcohol and the secondary alcohol decreases with increase of methanol content in the mobile phase. A unique observation is an extremum for 1-phenyl-3-propanol in the plot of $T{\Delta}{\Delta}S^o$ vs. methanol volume %. The positive sign of $T{\Delta}{\Delta}S^o$ of 3-phenyl-1-propanol implies that the entropy of 3-phenyl-1-propanol is greater than that of the hypothetical alkylbenzene (the same size and shape as phenylpropanol) in the mobile phase.

• FOCUS: LIFE SCIENCE
• /
• 제1호
• /
• pp.3.1-3.7
• /
• 2024

The article discusses the critical role of chromatography in the analysis and purification of proteins in biopharmaceuticals, emphasizing the importance of comprehensive characterization for ensuring their safety and efficacy. It highlights the use of Avantor® ACE® HPLC columns for the separation and purification of proteins, focusing on the analysis of intact proteins using reversed-phase liquid chromatography (RPLC) with fully porous particles. This article also details the application of different mobile phase additives, such as TFA and formic acid, and emphasizes the advantages of using type B ultra-pure silica-based columns for efficiency and peak shape in biomolecule analysis. Additionally, it addresses the challenges of analyzing intact proteins due to slow molecular diffusion and introduces the concept of solid-core (or superficially porous) particles, emphasizing their benefits over traditional porous particles for the analysis of therapeutic proteins. Furthermore, it discusses the development of Avantor® ACE® UltraCore BIO columns, specifically designed for the high-efficiency separation of large biomolecules, such as proteins, and demonstrates their effectiveness in achieving high-resolution separations, even for higher molecular weight proteins like monoclonal antibodies (mAbs). In addition, it underscores the complexity of analyzing and characterizing intact protein biopharmaceuticals, requiring a range of analytical techniques and the use of wide-pore stationary phases, operated at elevated temperatures and with relatively shallow gradients. It highlights the comprehensive range of options offered by Avantor® ACE® wide pore columns, including both fully porous and solid-core particles, bonded with a variety of complementary stationary phase chemistries to optimize selectivity during method development. The use of ultrapure and highly inert base silica is emphasized for enabling the use of lower concentrations of mobile phase modifiers without compromising analyte peak shape, particularly beneficial for LC-MS applications. Then the article concludes by emphasizing the significance of reversed-phase liquid chromatography and its compatibility with mass spectrometry as a valuable tool for the separation and analysis of intact proteins and their closely related variants in biopharmaceuticals.

• Environmental Analysis Health and Toxicology
• /
• 제12권3_4호
• /
• pp.75-84
• /
• 1997

Chromatographic retention behavior and separation of various phenol derivatives on a Partisil 10 ODS 3 column-with mobile phase containing $\alpha$-cyclodextrin-were systematically studied. The decrease in k' values caused by the addition of cyclodextrins in the mobile phase was based on the formation of an inclusion complex, resulting in weakening of the hydrophobic interaction between solutes and the stationary phase. The content of the organic solvent in the mobile phase also influenced k' values of the solutes, and k' values increased with a decrease of the content of organic solvent in the mobile phase. A simple equation has been derived that reveals the hyperbolic dependence of the capacity factor on the total concentration of cyclodextrin. A plot of the reciprocal of the capacity factor against (CD)$_T$ gives a straight line and the dissociation constant, K$_D$, of the inclusion complex can be calculated from the slope. The capacity factor decreased with increasing temperature. The enthalpy was calculated from the slope of van't Hoff plots. Under optimum conditions, some mixtures of phenol derivatives were able to separated successfully.

• Archives of Pharmacal Research
• /
• 제17권4호
• /
• pp.244-248
• /
• 1994

A stereoselective and sensitive high performance liquid chromatography using fluoresecence deterctor was examined for the determination of R(-) and S(+)-salbutamol in human plasma. Solid phase extraction method using silica as sorbent was used to extract salbutamol racemates from the plasma matrices. After fractionation and freeze-drying of the eluates containing salbutamol racemates, they were separated and quantified on a chirla stationary column. The detection limit of each enantiomer was 2 ng/ml in human plasma (S/N=3).

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제5권5호
• /
• pp.382-385
• /
• 2000

A mathematical model was developed, based on the time dependent changes of the specific growth rate, for prediction of the typical microbial cell growth in batch cultures. This model could predict both the lag growth phase and the stationary growth phase of batch cultures, and it was tested with the batch growth of Trichoderma reesei and Lactobacillus delbrueckii.

• 수산해양기술연구
• /
• 제53권4호
• /
• pp.349-356
• /
• 2017

The catch composition of commercially important species of the stationary lift net at Barangay Gines, Miagao, Iloilo, the Philippines was investigated from December 2013 to May 2014 during the different phases of the moon. A total of 486 kg of fish coming from 12 different genera, including mollusk and crustaceans, was caught and identified from the catch of the stationary lift net. Among the 12 genera identified from the catch of stationary lift net, anchovy (Stolephorus), sardines (Sardinella), squid (Loligo) and mysid shrimp (Acetes) were considered to be commercially important due to their value. Acetes catch was highest during the new moon in the month of January. Loligo catch was also high during the new moon except in the month of May. Stolephorus catch was also highest during the new moon except in the month of January. Sardinella catch was highest during the first quarter in the month of February. Full moon had the lowest catch all throughout the duration of the study while new moon had the highest catch during December 2013 to March 2014 and first quarter was the highest in the months of April and May.

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 1996년도 한국생물과학협회 국제학술대회
• /
• pp.184.2-184
• /
• 1996

No Abstract, See Full Text

• Bulletin of the Korean Chemical Society
• /
• 제26권6호
• /
• pp.998-1000
• /
• 2005