• Analytical Science and Technology
• /
• v.7 no.4
• /
• pp.427-434
• /
• 1994

For the analysis of the relatively volatile lead in blood by GFAAS(graphite furnace atomic absorption spectrophotometer), one can not raise the ashing temperature beyond certain degree due to the elevation of the baseline. Previous investigations showed that background is stabilized when the ashing temperature is raised to $700^{\circ}C$ using a matrix modifier. In this study, same result was obtained at the ashing temperature of around $550^{\circ}C$ even when the matrix modifier is not used and only Triton X-100 is used as a diluent, on an instrument which is equipped with both temperature and current controller(Shimadzu, AA-6501S) and thus the temperature control is fast and accurate. Background correction methods of $D_2$ arc and SR(self reversal) were reviewed. The results show that the absorbance is higher for the $D_2$ arc method, but the background correction is higher for the SR method.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.2
• /
• pp.159-164
• /
• 2013

Difficulty of torque measurements in high-speed permanent magnet (HSPM) motors has necessitated the development of improved torque calculations. Hence, this paper presents an analytical torque calculation of a high speed permanent magnet (HSPM) motor based on the power factor angle. On the basis of analytical magnetic field solutions, the equations for circuit parameters such as back-emf and synchronous inductance are derived analytically. All analytical results are validated extensively by non-linear finite element (FE) calculations and measurements. The internal angle (${\delta}$) between the back-emf and the phase current is calculated according to the rotor speed by using analytical circuit parameters and the measured power factor because this angle is not measured but estimated in case of sensorless drive of the HSPM motor, significantly affecting torque calculation. Finally, the validity of the torque analysis method proposed in this paper is confirmed, by showing that the torque calculated on the basis of the internal angle is in better agreement with the measurements.

• Ocean and Polar Research
• /
• v.37 no.1
• /
• pp.1-9
• /
• 2015

An approach based on the combined use of a 2D shallow water model and analytical 1D long wave run-up theory is proposed which facilitates the forecasting of tsunami run-up heights in a more rapid way, compared with the statistical or empirical run-up ratio method or resorting to complicated coastal inundation models. Its application is advantageous for long-term tsunami predictions based on the modeling of many prognostic tsunami scenarios. The modeling of the Chilean tsunami on February 27, 2010 has been performed, and the estimations of run-up heights are found to be in good agreement with available observations.

• Analytical Science and Technology
• /
• v.23 no.3
• /
• pp.278-283
• /
• 2010

This study was performed to compare the analytical results among L2000DX and two GC/ECD methods (rapid and conventional). 15 samples of transformer oils were collected to compare the analytical results. In the analytical results of PCBs-containing transformer oil, the PCBs concentrations were in the range of 4.4 mg/L to 182.8 mg/L with L2000DX, N.D. to 14.63 mg/L with conventional GC/ECD, and N.D. to 13.03 mg/L using rapid GC/ECD. The PCB concentrations detected with the L2000DX showed a large difference to those detected with GC/ECD methods. Otherwise, little difference was shown between the two GC/ECD methods at a concentration range lower than 4 mg/L, although the rapid GC/ECD method tended to detect a slightly lower concentration near the regulation criteria of Korea for 2 mg/L.

• Food Science and Preservation
• /
• v.24 no.6
• /
• pp.795-801
• /
• 2017

Aralia elata Seemann (AE) has long been used as a folk medicine for the treatment of various diseases including diabetes mellitus, anti-arthritic, and anti-gastric ulcer agent in Korea, Japan, and China. This study was performed to establish a simple and reliable HPLC/UV analytical method for determination of most active anti-hypertensive compound, a 3-O-${\alpha}$-L-rhamnopyranosyl($1{\rightarrow}$2)-${\alpha}$-L-arabinopyranosyl hederagenin 28-O-${\beta}$-D-xylopyranosyl($1{\rightarrow}6$)-${\beta}$-D-glucopyranosylester (HE) for the standardization of the shoot extract of AE as a health functional food ingredient. The quantitative analytical method of HE was optimized by HPLC analysis using reverse-phase C18 column at $40^{\circ}C$ with $H_2O$ and acetonitrile (70:30, v/v) as an isocratic mobile phase at a flow rate of 1.0 mL/min and detection wavelength of UV 205 nm. This HPLC/UV analytical method showed good specificity and high linearity in the tested range of 0.03125-2.0mg/ml with excellent coefficient of determination ($R^2$) of 0.9999. The limit of detection and limit of quantification were $12.0{\mu}g/mL$ and $36.5{\mu}g/mL$, respectively. Relative standard deviation (RSD) values of data from intra- and inter-day precision were less than 0.2% and 0.1%, respectively. These results indicate that the established HPLC/UV analytical method is very simple, specific, precise, accurate, and reproducible and thus can be useful for the quantitative analysis of HE as a functional anti-hypertensive compound in AE extract.

• Analytical Science and Technology
• /
• v.32 no.5
• /
• pp.163-172
• /
• 2019

Methamphetamine (MA) is currently the most abused illicit drug in Korea and its major metabolite is amphetamine (AP). As MA exist as two enantiomers with the different pharmacological properties, it is necessary to determine their respective amounts in a sample. Thus a chiral stationary phase liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of d-MA, l-MA, d-AP, and l-AP in human urine. Urine sample ($200{\mu}L$) was diluted with pure water and purified using solid-phase extraction (SPE) cartridge. A $5-{\mu}L$ aliquot of SPE treated sample solution was injected into LC-MS/MS system. Chiral separation was carried out on the Astec Chirobiotic V2 column with an isocratic elution for each enantiomer. Identification and quantification of enantiomeric MA and AP was performed using multiple reaction monitoring (MRM) detection mode. Linear regression with a $1/x^2$ as the weighting factor was applied to generate a calibration curve. The linear ranges were 25-1000 ng/mL for all compounds. The intra- and inter-day precisions were within 3.6 %, while the intra- and inter-day accuracies ranged from -5.4 % to 11.8 %. The limits of detection were 2.5 ng/mL (d-MA), 3.5 ng/mL (l-MA), 7.5 ng/mL (d-AP), and 7.5 ng/mL (l-AP). Method validation parameters such as selectivity, matrix effect, and stability were evaluated and met acceptance criteria. The applicability of the method was tested by the analysis of genuine forensic urine samples from drug abusers. d-MA is the most common compound found in urine and mainly used by abusers.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.35 no.4
• /
• pp.48-54
• /
• 2012

In this paper, quantitative and systematic procedures for establishing Key Performance Indicators (KPI's) of R&D departments are presented. The proposed methodology is composed of 4 steps : 1) identification of critical success factors, 2) identification of potential KPI's, 3) determination of KPI's and 4) monitoring and execution. A Strategy Map has been presented to better align KPI's with a company's competitive strategies. Also, Analytical Hierarchy Planning (AHP) is used to determine weights of KPI's and Data Envelopment Analysis (DEA) is used to analyze the effectiveness of R&D departments. To demonstrate its validity of the proposed method, it has been applied to the R&D divisions of a semiconductor company.

• Analytical Science and Technology
• /
• v.36 no.1
• /
• pp.53-58
• /
• 2023

2'-Hydroxy-3',4'-methylenedioxy-3,4,5-trimethoxychalcone (HMTC) is a newly synthesized chalcone that affects proliferation, cytotoxic potential and apoptosis in human leukemia cells. However, no validated determination method has been described so far for HMTC in biological samples. Thus, we developed a liquid chromatographic method using a tandem mass spectrometry to determine HMTC in rat plasma. Liquid-liquid extraction with ethyl acetate was used for the clean-up procedure. The analyte was separated on a reversedphase column with mobile phase of distilled water and acetonitrile (2:8, v/v, including 0.1 % formic acid). The ion transition of the precursor to the product ion was principally deprotonated ions [M-H]^- at m/z 356.8 → 327.2 for HMTC. This analytical method was successfully applied in pharmacokinetic study of HMTC after intravenous administration in rats.

• Journal of Drive and Control
• /
• v.10 no.2
• /
• pp.13-22
• /
• 2013

It is difficult to analytically derive a volumetric displacement formula of gerotor hydraulic pump/motor because geometric shape of rotors is complicated. An analytical method about the volumetric displacement is proposed in this work, which is relatively easy and based upon two physical concepts. The first one is energy conservation between hydraulic energy of the pump/motor and mechanical input/output energy. The second concept is torque equilibrium with respect to inner and outer rotors. The formula about the volumetric displacement is derived for the common case of inner and outer rotors rotate with respect to fixed axes. The formula is verified by comparing another analytical displacement formula, and it is numerically verified by comparing numerical results, which is calculated for geometric specification of a motor. The numerical displacement is calculated through CAD software program and MATLAB program. The proposed analytical formula can be utilized in analysis and design of hydraulic gerotor motors.

• Steel and Composite Structures
• /
• v.25 no.2
• /
• pp.127-139
• /
• 2017

In this paper, an exact analytical solution for simply supported sandwich plate which considers the permeation effect of adhesives is presented. The permeation layer is described as functionally graded material (FGM), the elastic modulus of which is assumed to be graded along the thickness following the exponential law. Based on the exact three-dimensional (3-D) elasticity theory, the solution of stresses and displacements for each layer is derived. By means of the recursive matrix method, the solution can be efficiently obtained for plates with many layers. The present solution obtained can be used as a benchmark to access other simplified solutions. The comparison study indicates that the finite element (FE) solution is close to the present one when the FGM layer in the FE model is divided into a series of homogeneous layers. However, the present method is more efficient than the FE method, with which the mesh division and computation are time-consuming. Moreover, the solution based on Kirchhoff-Love plate theory is greatly different from the present solution for thick plates. The influence of the thickness of the permeation layer on the stress and displacement fields of the sandwich plate is discussed in detail. It is indicated that the permeation layer can effectively relieve the discontinuity stress at the interface.