• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.363-367
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• 2009

An isotope-dilution flow-injection electrospray/mass spectrometric method was developed for the accurate determination of glucosamine contents in pharmaceutical formulations. Samples were extracted by methanol. After spiking glucosamine-1-$^{13}C_1$ as an internal standard, the extracts were then analyzed by flow-injection ESI/MS in a selected ion monitoring (SIM) mode to detect [M+H]$^+$ ions of the analyte and its isotope analogue at m/z 180 and m/z 181, respectively. Confirmatory measurements were made by selectively monitoring the collisionally induced dissociation channels of m/z 180 $\rightarrow$ m/z 72 and m/z 181 $\rightarrow$73, respectively, to test the possibility of bias in the SIM method due to matrix interferences, but any significant bias in the SIM mode was not observed. Repeatability and reproducibility studies showed that the flow-injection ESI/MS method is a reliable and reproducible method which can provide a typical method precision of 1.0 %. Other results for the method validation are reported.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.2 no.2
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• pp.169-179
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• 1998

This paper was performed to estimate interrelations between humus level of sediments and nutrient release from sediments in Dae-cheong reservoir. For investigations, sediments were sampled in June and October, in 1997 at fish farms, embayment, and the main stream of Dae-cheong reservoir. Items for investigation are as follows; water content, weight loss on ignition(IG), porosities of sediments, contents of element such as hydrogen, nitrogen, carbon, and nutrient release rates. Water contents and porosities were measured to conjecture the physical trait and grain size trait. Weight loss on ignition was measured to determine the contents of organic substance. For determination of the humus level of sediments, carbon and nitrogen contents were measured by elemental analyzer. As a result of elemental analysis, C/N ratio was determined in the range of $3.0\~13.1$. From the elemental analysis, humus level of Dae-cheong reservoir sediment was estimated from mesohumic state to oligotrophic state. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentrations of interstitial water and overlying water were measured. By using the concentration difference between interstitial water and overlying water and using the Fick's diffusion law, the release rates of phosphorus and nitrogen from the sediment samples were calculated. Release rates of nutrients which directly influence to the water quality were $0.05\~8.63mgP/m^2day$ and $4.99\~36.56mgP/m^2day$. It was found that release rate was measured higher in the 1st sampling period than in the 2nd sampling period. For the determination of phosphorus content in sediment, TPs were measured in 807\~1542{\mu}g/g$ in the 1st samling period and $677\~5238{\mu}g/g$ in the End samling period. Phosphorus release rate and phosphorus content were not interrelated each other.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.8
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• pp.699-704
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• 2015

Laser-assisted machining has shown its potential to significantly improve product quality and reduce manufacturing costs; additionally, laser-assisted turning (LAT) and laser-assisted milling (LAM) have been studied by numerous researchers. A research study on the determination of the distance between the laser heat source and the tool for laser-assisted machining, however, has not yet been attempted; we conducted such an analysis by using a finite-element method and heat-transfer equation. The results of this analysis can be used as a reference for the determination of the distance between the laser heat source and the tool for laser-assisted machining.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.31-34
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• 2001

The customer unsatisfaction in the new products exists, though the most of enterprises using QFD. It is mainly caused by the failure of corrective determination of technical importance rating(TIR). To derive the technical importance rating, the impact of the fulfillment of design requirements on the satisfaction of customer requirements must first be quantified. This has been accomplished through the use of a 1-3-9 or a 1-5-9 scale and ignored the peak of the house of quality(HOQ). In this paper we suggested the methodology reflecting effectiveness among engineering characteristics and adjusting the relationship strength between customer attribute(CA) and engineering characteristic (EC), by using limit probability and PCMR(pairwise comparison and median rank). With using this method, the determination of TIR would be more suitable for the voice of customers objectively. Here negative correlation is ignored.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.5
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• pp.733-737
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• 2012

Determination of sex origin of cattle meat by fast and reliable molecular methods is an important measure to ensure correct allocation of export refunds particularly in European countries and also female cattle (cow) slaughter is legally banned in India because of religious beliefs. Based on the DEAD box protein gene located on the X and Y chromosomes, 2 pair of primers were designed and the system of PCR was optimized. Upon PCR amplification, male tissue showed 2 bands, while female tissue resulted in only one band. The accuracy and specificity of the primers was assessed using DNA template extracted from cattle meat of known sex. The protocol was subjected to a blind test and showed 100% concordance, proving its accuracy and reliability.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.99-103
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• 2008

Solvent extraction using salphen as a ligand has been investigated for the selective separation and determination of trace Fe(II) and Fe(III). A salphen ligand was synthesized, and solvent extraction variables, such as solution pH, the concentration of salphen, the type of organic solvent, auxiliary agents, oxidants and the effect of interference were optimized. Salphen is stable at pH 3-4, and Fe(III)-salphen complexes can be selectively extracted into an MIBK(4-methyl-2-pentanone) phase from an aqueous solution within this pH range. For the determination of the total amount of iron in 100 mL of aqueous solution, Fe(II) ions were completely oxidized using 0.05 mL of 3.5% H2O2 without side reactions. To evaluate its applicability, the proposed method was applied to determine trace Fe(II) and Fe(III) in several kinds of water samples. Reproducible results were obtained with RSD of less than 3.0%, and the recoveries for this reliability were obtained with 91-112%.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.78-89
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• 1992

The most important criteria of quality of meshing and contact of gears are the low level of noise and the sufficient dimensions and location of the contact. A new approach for determination of machine-tool settings for spiral bevel gears is proposed. The proposed settings provide a function of transmission errors, the desired location and orientation of contact. The function is able to absorb piece-wise linear functions of transmission errors that are caused by the gear misalignment and to reduce the gear noise. The determination of pinion machine-tool settings is based on the local synthesis of gears. A computer program for simulation of meshing bearing contact and determination of transmission errors for misaligned has been developed.

• Korean Journal of Pharmacognosy
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• v.30 no.3
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• pp.332-334
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• 1999

Corydalis Tuber has been used in traditional medicine for an analgesic, antispasmodic and gastric ulcers. For the quality control on this drug, isolation and quantitative determination of berberine and coptisine from Corydalis ternata Nakai (Papaveraceae) has been conducted by using HPLC method. Berberine and coptisine in quarternary alkaloidal fraction from the crude drug were separated on silicagel column using a $CHCl_3:MeOH\;(85:15)$ and $CHCl_3:MeOH:H_2O\;(70:30:4)$ as an eluent, and the average contents were about 0.93 and 0.36%.

• Natural Product Sciences
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• v.17 no.2
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• pp.104-107
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• 2011

In order to facilitate the quality control of betaine from the fruits of Lycium chinense, we have developed a rapid and simple method for quantitative determination. Determination was achieved on a Discovery C18 column with an isocratic solvent system of 0.32% perfluoropentanoic acid aqueous-acetonitrile at a flow-rate of 0.5 mL/min and detected an ELSD. The method was reproducible with intra- and inter-day variations of less than 6% (R.S.D). The recoveries were in the range of 90.01~100.05%. The method turned out to be fast and simple, furthermore, to have a good selectivity and sensitivity for the quantity determination of betaine in the fruits of L.chinense.

• Herbal Formula Science
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• v.18 no.2
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• pp.251-257
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• 2010

Objectives : To develop and validate High-performance liquid chromatography-photodiode array methods for simultaneous determination of two constituents in Oryeong-san(ORS). Methods : Reverse-phase chromatography using a Gemini C18 column operating at $40^{\circ}C$, and photodiode array(PDA) detection at 280 nm, were used for quantification of the two marker components of ORS. The mobile phase using a gradient flow consisted of two solvent systems. Solvent A was $H_2O$ and solvent B was acetonitrile. Results : Calibration curves were acquired with correlation coefficient ($r^2$)>0.9999, and the relative standard deviation(RSD) values(%) for intra- and inter-day precision were not exceed 1.0%. The recovery rate of each compound was in the range of 93.01-104.16%, with an RSD less than 2.0%. The contents of two compounds in ORS were 1.10-3.72 mg/g. Conclusions : The established HPLC method will be helpful to improve quality control of ORS.