Recent works on massive multiple-input multiple-output (MIMO) have shown that a potential breakthrough in capacity gains can be achieved by deploying a very large number of antennas at the base ...station. In order to achieve the performance that massive MIMO systems promise, accurate transmit-side channel state information (CSI) should be available at the base station. While transmit-side CSI can be obtained by employing channel reciprocity in time division duplexing (TDD) systems, explicit feedback of CSI from the user terminal to the base station is needed for frequency division duplexing (FDD) systems. In this paper, we propose an antenna grouping based feedback reduction technique for FDD-based massive MIMO systems. The proposed algorithm, dubbed antenna group beamforming (AGB), maps multiple correlated antenna elements to a single representative value using predesigned patterns. The proposed method modifies the feedback packet by introducing the concept of a header to select a suitable group pattern and a payload to quantize the reduced dimension channel vector. Simulation results show that the proposed method achieves significant feedback overhead reduction over conventional approach performing the vector quantization of whole channel vector under the same target sum rate requirement.
Owing to the high cost of radio frequency (RF) chains and power consumption of broadband signals, it is suitable to include both analogue and digital processing for millimetre wave (mmWave) ...beamforming. In this study, hybrid beamforming (HBF) schemes are considered for multi-user downlink mmWave systems. RF beamforming schemes are proposed for HBF transmission with perfect channel state information at transmitter (CSIT) and limited feedback information in the multi-user mmWave channel. Simulation results show that proposed HBF schemes enhance sum rate performance than conventional HBF schemes in both cases of perfect CSIT and limited feedback.
Ethanol intake can alter pharmacokinetics by increasing the solubility or enhancing the absorption of concomitant drugs. Here, a selective, sensitive and reproducible high‐performance liquid ...chromatography–tandem mass spectrometry method for the quantitative analysis of nicardipine in rat plasma was developed using simple protein precipitation. The calibration curve was linear over a concentration range of 1–2,000 ng/ml (r2 > 0.998). Accuracy ranged from 93.4 to 112.2% and precision was within 12.1% from three independent analytical batches. Stable conditions for the quantification of nicardipine in rat plasma were established in various conditions, including sample storage and handling. The matrix effect was negligible, and recovery was consistent at three different levels of quality control sample. The method was applied to assessment for the effect of ethanol on the pharmacokinetics of nicardipine in rats. The oral bioavailability of nicardipine was increased from 5.4 to 9.4% in Sprague–Dawley rats by concomitant oral administration of ethanol whereas the half‐life was not altered. The findings indicated that concomitant ethanol intake can increase systemic drug exposure by increasing gastrointestinal absorption, especially poorly soluble drugs. This study provides an insight for further investigation of the alteration of the pharmacological effect of poorly soluble drugs owing to ethanol intake.
Recent works on massive multiple-input multiple-output (MIMO) have shown that a potential breakthrough in capacity gains can be achieved by deploying a very large number of antennas at the ...basestation. Although transmit-side channel state information (CSI) can be obtained by employing channel reciprocity in time division duplexing (TDD) systems, explicit feedback of CSI from the user to the basestation is required for frequency division duplexing (FDD) systems. In this paper, we propose an antenna grouping based feedback reduction technique for FDD-based massive MIMO systems. The proposed algorithm, dubbed antenna group beamforming (AGB), groups antenna elements using pre-designed patterns. The proposed method introduces the concept of using a header of overall feedback resources to select a suitable group pattern and the payload to quantize the effective channel vector. Simulation results show that the proposed method achieves significant feedback overhead reduction over conventional approach.
•HPLC-MS/MS method for the simultaneous determination of PFOA and linear PFOS in human sera was developed and fully validated.•A sample preparation method was optimized by combining solid-phase ...extraction and protein precipitation.•Chromatographic separation of the linear PFOS from branched isomers was completely achieved.•Using 13C-labeled PFOA and PFOS as calibrators, the method overcame a lack of PFOA- and PFOS-free human serum.•The median concentration of linear PFOS was approximately 2.6-fold higher than that of PFOA.
Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are synthetic chemicals that have been used in various industries and household products. These can easily accumulate in the human body, causing adverse effects on human health. In this study, a high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous analysis of PFOA and linear PFOS in human serum. Owing to a lack of PFOA- and PFOS-free human serum, 13C8-PFOA and 13C8-PFOS were used as surrogate analytes for quantification. A sensitive and selective sample preparation method was developed and optimized by combining solid-phase extraction and protein precipitation method. The lower limit of quantification was 0.05 ng/mL, and the analytical response was linear up to 10 ng/mL for both PFOA and linear PFOS. Chromatographic separation of the linear PFOS from branched isomers was achieved within 5.5 min. The method was validated at various concentrations and afforded acceptable accuracy and precision values. After validation, the method was successfully applied to evaluate the exposure levels of PFOA and linear PFOS in the Korean population. The serum concentrations of PFOA and linear PFOS were 0.42–28.3 ng/mL and 0.81–57.6 ng/mL, respectively. The median concentration of linear PFOS was approximately 2.6-fold higher than that of PFOA. The concentration of PFOA was higher in women than men (p < 0.05) and that of linear PFOS was not significantly different between men and women. Therefore, a sensitive, selective, and reliable bioanalytical method was developed and validated. This method can potentially be applied to biomonitoring studies involving PFOA and linear PFOS.
A concept of full-dimension MIMO (FD-MIMO) adopting 2-dimensional (2D) antenna array has been proposed with intent to cope with practical challenges of massive MIMO systems. In this paper, we ...investigate an FD-MIMO operation that can be transparently applied with current 3GPP LTE specifications, and propose a novel method that facilitates an accurate estimation of channel quality indicator (CQI) at base station (BS). We first introduce a feedback scheme in which horizontal and vertical dimension channel information are separately reported. To further improve accuracy of modulation and coding scheme (MCS) selection to maximize system throughput, we propose an enhanced feedback scheme that is helpful to more accurate CQI estimation at the BS. In the evaluation results, we show performance improvement of the proposed scheme over the conventional MIMO scheme.
A gold nanosphere in water is considered to attain special stability in derivatization like an artificial atom when the octet rule is satisfied by forming four covalent bonds with two ...5′-phosphorothioate-modified oligonucleotide molecules. Owing to this, the hybridization of two mutually complementary gold-bound oligonucleotides makes gold nanospheres preferentially connected linearly by duplexes to produce strands like linear artificial molecules. We have then fixated the linear strands of DNA-linked gold nanospheres by reducing Ag
+ ion clusters immobilized around duplexes to show the absorption spectrum of silver-coated artificial-molecular nanorods.
A gold nanosphere is considered to attain special stability in derivatization when the octet rule is satisfied by forming four covalent bonds with two 5′-phosphorothioate-modified oligonucleotide molecules.
To evaluate the possibility for development of apple wine containing medicinal herbs, we have prepared ‘Fuji’ apple (
Malus domestica
) wines containing pine (
Pinus densiflora
Siebold et Zuccarini) ...needle and
hwanggi
(Radix Astragali)/mistletoe (
Viscum album
). Normal apple wine was fermented rapidly, but after 40 days fermentation/maturation, the final ethanol content, pH, total acidity, and contents of sugar/organic acid showed similar levels in 3 kinds of apple wines. In other hands, the total phenols content, antocyanins content, and brightness were higher in apple-pine wine and apple-herb wine than in normal apple wine. Apple-herb wine had higher values in total phenol contents, brightness, free amino acid contents, and quenching activity for ABTS free radicals than normal apple wine, and had similar sensory evaluation values with normal apple wine. Taken together, it is supposed that
hwanggi
and mistletoe might provide functional components to normal apple wine and might be applied to development of functional apple wines.
For chip-to-chip parallel interfaces, maintaining low power consumption while achieving high aggregate bandwidth is the key trend. Forwarded-clock (FC) architecture is well suited to this trend ...because of the simple structure and inherent correlation of clock and data jitter 1. Clock-recovery circuits consume a large portion of the I/O power. PLL/DLLs with a phase interpolator are widely used for the clock recovery circuits. However, they dissipate high power and jitter-tracking bandwidth (JTB) is low (PLL) or high (DLL), degrading the jitter correlation between data and clock. Recently, injection-locked oscillators (ILOs) have drawn much attention for the clock-recovery circuit of the FC interfaces due to their low power consumption 3-6. By de-tuning the free-running frequency of an ILO, clock deskew can be performed and multiphase clocks can be generated without an additional multiphase generator. Also, ILOs can provide JTB of several hundred MHz, which is optimal for the FC interfaces in terms of the jitter correlation and BER 5.
모델링 기반 사고 대응 절차 수립 방법에 관한 연구 설지우; Ji Woo Seol; 채충근 ...
Korean Chemical Engineering Research(HWAHAK KONGHAK), 55(2),
04/2017, Volume:
55, Issue:
2
Journal Article
Peer reviewed
Open access
사고 대응 가이드라인은 사고 발생 시 그 영향을 줄이기 위한 수단으로 중요한 역할을 한다. 유용한 사고 대응 가이드라인의 개발을 위하여 개발 절차에 공학적 방법론의 적용이 필요하다. 본 논문에서는 기존에 존재하는 사고 대응 가이드라인 작성 방법론에 Bow-Tie 기법, 사고 전개 모델, 위험 대응 의사결정 등 위험 관리 기법을 적용하였다. 이러한 방법으로 ...일반화된 사고 대응 가이드라인 작성 절차를 제안하였으며, 직접적으로 활용할 수 있도록 Sheet를 개발하고, 특정 Case를 적용하여 Sample Guide를 작성하였다.
Emergency response guidelines play an important role which reduce consequence of accident. For development of useful emergency response guidelines, engineering methodology should be applied to the development procedures. In this study accident propagation model, bow-tie methods, emergency response decision methods were applied to existing emergency response guideline develop procedure. In this way, this study suggest generalized emergency response guideline develop procedures. Also a sheet was developed using suggested procedures to make sample guidelines for a case.
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