• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2663-2670
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• 2013

The purpose of stability testing is to provide evidence about how the quality of a drug varies with time under the influence of a variety of environmental factors. In this study, erythropoietin (EPO) was analyzed under different pH (pH 3 and pH 9) and temperature ($25^{\circ}C$ and $40^{\circ}C$) conditions according to current Good Manufacturing Practice (cGMP) and International Conference on Harmonisation (ICH) guidelines. The molecular weight difference between intact EPO and deglycosylated EPO was determined by SDS-PAGE, and aggregated forms of EPO under thermal stress and high-pH conditions were investigated by size exclusion chromatography. High pH and high temperature induced increases in dimer and high molecular weight aggregate forms of EPO. UPLC-ESI-TOF-MS was applied to analyze the changed modification sites on EPO. Further, normal-phase high-performance liquid chromatography was performed to identify proposed glycan structures and high pH anion exchange chromatography was carried out to investigate any change in carbohydrate composition. The results demonstrated that there were no changes in modification sites or the glycan structure under severe conditions; however, the number of dimers and aggregates increased at $40^{\circ}C$ and pH 9, respectively.

• Mass Spectrometry Letters
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• v.6 no.1
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• pp.13-16
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• 2015

This study demonstrated the stabilizing role of a cyclodextrin on Keggin $[PW_{12}O_{40}]^{3-}$ via hydrogen bonding complexation unveiled by ESI-MS. The distinctive fragmentation pathways of the $\{PW_{12}\}/{\gamma}$-CD complexes from that of discrete $[PW_{12}O_{40}]^{3-}$ showed that the so-called "weak" non-covalent interactions can effectively change the dissociation chemistry of POM in the gas phase. The influence of different types of solvents and organic additives such as ${\gamma}$-CD on the stability of Keggin $[PW_{12}O_{40}]^{3-}$ was also addressed firstly by ESI-MS.

• Korean journal of food and cookery science
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• v.18 no.4
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• pp.455-460
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• 2002

This experiment was conducted to obtain basic information on the natural spice of Elsholtzia splendens, which is one of the native Korean aromatic plants for aromatic, medicinal and ornamental uses. The overall acceptability and the masking effects on the fetid smell of beef were investigated with Elsholtzia splendens-flavored oils by sensory evaluation. The ability of an electronic nose with six metal oxide sensors to classify Elsholtzia splendens flavored oils based on their odors was studied. The response by electronic nose was analyzed by principal component analysis (PCA). In EOI, EOII, and ESI, (이것들이 무엇을 의미하는지 기술할 필요가 있음). overall acceptability of French dressing showed a same level of preference during storage. Fetid smell of beef was not changed by the addition of 4 types of Elsholtzia splendens-flavored oil during storage. In EO I -flavored oil, the proportion of 1st principal component was 0.829, and the proportion of 1st principal component was 0.818 in ESI-flavored oil. The PCA plot was used to detect stored Elsholtzia splendens flavored oils.(앞 뒤 문맥이 안맞음. 뒤에 이어지는 글이 있는지\ulcorner).

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.606-612
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• 2014

Vehicle simulation models for noise and vibration prediction have been developed so far generally in two schemes. One is FE models generally used for problems below 200 Hz such as booming noise, and the other is SEA models for high frequencies of more than 1 kHz, representatively related to sound packages. There have been many researches to develop a simulation model for 200~1000 Hz, so-called mid-frequency region, and this paper shows one practical result that covers the trimmed body of a sedan vehicle. The simulation model is developed based on an FE model, and then FE elements at some areas are substituted with SEA elements to reduce DOFs. SEA panels are described by modal density, radiation efficiency, stiffness and damping characteristics that are found from some numerical assessments. Sound packages are modeled similarly as a conventional SEA model. The results obtained from the hybrid model were compared to experimental results. Predicted pressure and vibrational velocity generally show a good agreement. The developed simulation model and related technology are successfully being used in vehicle development process.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.429-434
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• 2002

The Synthetic Aperture Radar (SAR) data are considered to contain the greatest amount of information among various microwave techniques developed for measuring ocean variables from aircraft or satellites. They have the potential of measuring wavelength, wave direction and wave height of the ocean waves. But, it is difficult to retrieve significant ocean wave heights and surface current from conventional SAR data, since the imaging mechanism of ocean waves by a SAR is determined by the three basic modulation processes arise through the tilt modulation, hydrodynamic modulation and velocity bunching which are poorly known functions. Along-Track Interferometric (ATI) SAR systems can directly detect the Doppler shift associated with each pixel of a SAR image and have been used to estimate wave fields and surface currents. However, the Doppler shift is not simply proportional to the component of the mean surface current. It includes also contributions associated with the phase velocity of the Brags waves and orbital motions of all ocean waves that are longer than Brags waves. In this paper, we have developed a new method for extracting the surface current vector using multiple-frequency (L- & C-band) ATI SAR data, and have generated surface wave height information.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1221-1227
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• 2011

Ethyl pyruvate (EP) is known as a scavenger of reactive oxygen species (ROS) in the body through its role in the donation of diketone groups to metals to form an EP-metal complex. In order to develop a method for the quantification of EP in biological media, a sensitive and specific, high-performance liquid chromatographyelectrospray ionization-mass spectrometry (HPLC-ESI/MS) method is used to determine the EP-alkali metal ion binding species. The analyte was separated on a ZORBOX SB-C8 ($3.5{\mu}m$, $30mm{\times}2.1mm$ I.D.) column and analyzed in selected ion monitoring (SIM) mode with a positive ESI interface using the m/z 255 $[2M + Na]^+$ ion. The method was validated over the concentration range of $0.5-60.0\;{\mu}g$/mL under 1/9 (v/v) of acetonitrile/methanol solvent system with flow rate 0.05 mL/min. The limit of quantification (LOQ) was $0.5{\mu}g$/mL.

• Korean Journal of Veterinary Service
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• v.30 no.1
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• pp.1-12
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• 2007

A liquid chromatographic method has been developed for the analysis of aminoglycoside antibiotics (AMGs) using Heptafluorobutyric acid (HFBA) as a ion-pairing reagent. AMGs (amikacin, apramycin, dihydrostreptomycin, gentamicin, hygrosin B, kanamycin, neomycin, spectinomycin and tobramycin) were formed by reaction with HFBA as ion-pairing reagent. HFBA was attached to corresponding amino group of AMGs. These AMGs compounds were separated and detected by electrospray ionization mass spectrometry (ESI-MS). The experimental conditions for separation of AMGs were optimized and validated. A simple liquid chromatographic method for the determination of AMGs was demonstrated.

• Mass Spectrometry Letters
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• v.3 no.3
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• pp.78-81
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• 2012

The hydrophobic hydrocarbon chain and the polar sulfate group confer surfactant properties and enable them to be used as anionic surfactants. Anionic surfactants (AS) are known for their adverse impact on environment, particularly on aquatic ecosystem. In the present study a fast, sensitive and selective method for the determination and subsequent quantification of six anionic surfactants was developed using hydrophilic interactive liquid chromatography (HILIC) coupled to a electrospray ionization (ESI) mass spectrometer (MS), in the concentration range 15-20 ${\mu}g/L$. The capability of the method was established using regression analysis and ANOVA. The method performance was evaluated by analyzing real time surface water spiked with 1-dodecyl hydrogen sulfate at 15 ${\mu}g/L$. Combined efficiency of solid phase extraction and MS detection established recovery of 89% in presence of natural matrix. These results point out that HILIC coupled to multistage MS procedures can be a powerful technique for environmental applications concerning the screening of polar contaminants.

• Journal of Environmental Science International
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• v.26 no.12
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• pp.1399-1405
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• 2017

We compared the spatial distribution of several heat stress indices (the Wet-Bulb Globe Temperature(WBGT) index, Environmental Stress Index (ESI), and Modified Discomfort Index(MDI)) for the heat wave of June 6~August 26, 2016, in Daegu. We calculated the heat stress indices using data from the high density urban climate observation network in Daegu. The observation system was established in February. 2013. We used data from a total of 38 air temperature observation points (23 thermometers and 18 automatic weather stations). The values of the heat stress indices indicated that the danger level was very high from 0900-2000h in downtown Daegu. The daily maximum value of the WBGT was greater than or equal to $35^{\circ}C$. The differences in the heat stress indices from downtown and rural areas were higher in the daytime than at nighttime. The maximum difference was about 4 before and after 1400h, and the time variations of the heat stress indices corresponded well. Thus, we were able to confirm that the ESI and MDI can be substituted with the WBGT index.

• Mass Spectrometry Letters
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• v.5 no.4
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• pp.115-119
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• 2014

The Brazil nut (Bertholletia excelsa - Lecythidaceae) is considered a product with high economic value, being a food widely appreciated for its nutritional qualities. Although previous studies have reported the biochemical composition of Brazil nut oil, the knowledge regarding the phospholipid composition exhibits a disagreement: the composition of fatty acids present in the structures of phospholipids is reported as being different from the composition of the free fatty acids present in the oil. In this work, solid phase extraction (SPE) was employed to provide a fast extraction of the phospholipids from Brazil nuts, in order to compare the phospholipid profile of the in nature nuts and their fatty acids precursor present in the oil. The major phospholipids were characterized by mass spectrometry approach. Their fragmentation pattern through direct infusion electrospray ionization ion-trap tandem mass spectrometry ($ESI-IT-MS^2$) proved to be useful to unequivocal characterization of these substances. High resolution (HR) experiments through ESI using a quadruple time of flight mass spectrometry (QTOF) system were performed to reinforce the identifications.