• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1139-1143
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• 2002

Analysis of lysophosphatidic acids (LPAs) is of clinical importance as they can serve a potential marker for ovarian and other gynecological cancers and obesity. It is critically important to develop a highly sensitive and specific method for the early detection of gynecological cancers to improve the overall outcome of this disease. We have established a novel quantification method of LPAs in human plasma by negative ionization tandem mass spectrometry (MS-MS) using multiple reaction monitoring (MRM) mode without the conventional TLC step. Protein-bound lipids, LPAs in plasma were extracted with methanol : chloroform (2:1) containing LPA C14:0 as an internal standard under acidic condition. Following back extraction with chloroform and water, the centrifuged lower phase was evaporated and reconstituted in methanol. The reconstituted solution was directly injected into electrospray source of MS/MS. For MRM mode, Q1 ions selected were m/z 409, 433, 435, 437 and 457 which corresponds to molecular mass [M-H]- of C16:0, C18:2, C18:1, C18:0 and C20:4 LPA, respectively. Q2 ions selected for MRM were m/z 79, phosphoryl product. Using MS/MS with MRM mode, all the species of LPAs were completely separated from plasma matrix without severe interferences. This method allowed simultaneous detection and quantification of different species of LPAs in a plasma over a linear dynamic range of 0.01-25 ㎛olL-1 . The detection limit of the method was 0.3 pmol/mL, with a correlation coefficient of 0.9983 in most LPAs analyzed. When applied to the plasmas of normal and gynecological cancer patients, this new method differentiated two different groups by way of total LPA level.

• Food Science and Biotechnology
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• v.17 no.4
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• pp.787-793
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• 2008

A major polyphenolic compound extracted from omija (Schisandra chinensis) fruit was structurally identified, and its composition of major nutrients was investigated as well in this study. A dominating high performance liquid chromatography (HPLC) peak of water-extracted anthocyanin represented 94.1% of total absorbable compounds at 520 nm, which was further identified with HPLC-mass spectrometry (MS). As a result, mass-to-charge ratio (m/z) of the predominant anthocyanin was determined to be 727, and it was identical to molecular mass of cyanidin-3-xylosylrutinoside (Cya-3-O-xylrut). This is the first report that colorant of omija is predominantly composed of Cya-3-O-xylrut. Omija fruit contained exclusively 3 types of monosaccharide such as glucosc (0.68 g), galactose (0.01 g), and fructose (0.52 g) per 100 g of fruits. Several organic acids, citric (3.29 g), malic (1.4 g), acetic (0.4 g), and succinic acids (0.36 g) per 100 g of fruits, were detected by high performance anion exchange chromatography (HPAEC) analysis. During the compositional analysis of tree amino acid by HPLC, it was noticed that omija fruit contained substantial amount (0.01 g/100 g of fruits) of $\gamma$-amino butyric acid (GABA).

• Mass Spectrometry Letters
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• v.10 no.2
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• pp.43-49
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• 2019

The aim of this study was conducted to develop an analytical method to determine the concentration of ceftiofur residue in eel, flatfish, and shrimp. For derivatization and extraction, the sample was hydrolyzed with dithioerythritol to produce desfuroylceftiofur, which was then derivatized by iodoacetamide to obtain desfuroylceftiofur acetamide. For purification, the process of solid phase extraction (Oasis HLB) was used. The target analytes were confirmed and quantified in $C_{18}$ column using liquid chromatography-tandem mass spectrometry with 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B) as the mobile phase. The linearity of the standard calibration curve was confirmed by a correlation coefficient, $r^2>0.99$. The limit of quantification for ceftiofur was 0.002 mg/kg; the accuracy (expressed as the average recoveries) was 80.6-105%; the precision (expressed as the coefficient of variation) was below 6.3% at 0.015, 0.03, and 0.06 mg/kg. The validated method demonstrated high accuracy and acceptable sensitivity to meet the Codex guideline requirements. The developed method was tested using market samples. As a results, ceftiofur was detected in one sample. Therefore, it can be applied to the analysis of ceftiofur residues in fishery products.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.11
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• pp.31-43
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• 1996

In this paper, we propsoe an encryption algorithm of image information using a mass transfer function (MTF). The algorithm is based on a diffusion phenomenon of black ink when black ink dropped in the stationary water. We mathematically analyze the phenomenon, in consideration of characteristics of image information, and apply the results of analysis to the security of image transfer phenomenon. The cryptosystem proposed in this paper enables the security services of information in narrow-band channel communication network to be provided. And in transmission of important information, it can secure against intentional disturbance and violation. Also, it can guarantee the safe flow of information.

• Korean Journal of Hydrosciences
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• v.3
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• pp.45-59
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• 1992

The flow characteristics varying with rate of the radius of curvature to width (Rc/B) in open channel bends are investigated with a simplified numerical model. Secondary flow velocity and transverise bed slope are formulated from the equations of momentum and force balance analysis, respectively. The conservation equations of mass and streamwise momentum are simplified by depth integration and its solution could be obtained from the explicit finite difference method. Three sets of computer simulation are executed. The rates of Rc/B adopted in simulations are 2.7, 5.4 and 8.1. The terms analyzed in this paper secondary flow velocity, streamwise velocity, the path of maximum steamwise velocity, deviation angle, and mass-shift velocity.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1326-1331
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• 2009

Drying process in the cylindrical thin film layer of sludge with the thickness less than a few millimeters has been investigated. Thin film drying is specially designed and used to dry the viscous materials like sewage sludge. The thin film layer of sludge is dried on the metallic cylindrical surface through which thermal energy is supplied to the layer during drying. The wall temperature is assumed to be constant during drying in the present study for the simplification. In order to solve the equations, the mass transfer rate on the drying surface should be determined. The mass flux of evaporated water vapor on the surface is estimated with the formulation given in the literature. The effect of some physical parameters on drying has been examined to figure out the drying characteristics of the sludge layer.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.87-92
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• 1989

In this study, the nonlinear dynamic model of the systems which include the offshore structure, the surrounding sea water in terms of the added mass, the foundation in terms of frequency independent springs, dashpots, and the floating ice feature with its hydrodynamic added mass, are proposed for the problem of the large ice floes impact. Dynamic Analysis is performed on two site conditions, sand site and silt site, and on two seasons, winter and summer, for various ice floe velocities. As a result of study, Ice floes from energy balenced method is lower than that from dynamic modeling on sand site, and higher than the on silt site.

• Proceedings of the KSEG Conference
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• 2002.04a
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• pp.109-114
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• 2002

Development of a three-dimensional mine visualization model for a section of the mine is addressed first. Discontinuity orientation and location information was taken from this visualization model for use in slope stability analyses. Estimated shear strength properties of discontinuities and mechanical properties of intact rock from the rock mass samples obtained from the mine are discussed next. The third part of the paper is focused on the results obtained for maximum safe slope angles for the section considered of the mine based on block theory analysis conducted under only the gravitational forces using the mapped discontinuities at the mine. Finally, the effects of water that exist in the rock mass, a tension crack, slope face inclination, overall wedge height and double benching on factor of safety of wedge stability are illustrated through limit equilibrium slope stability analyses conducted on a single tetrahedral wedge belonging to potential key block category that exist in the investigated area of the mine.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1128-1133
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• 2008

Drying process in the thin film layer of sludge with the thickness less than a few millimeters has been investigated using the simple one-dimensional model. Thin film drying is usually used to dry the viscous materials like sewage sludge. The thin film layer of sludge is dried on the metallic surface through which thermal energy is supplied to the layer during drying. In order to solve the equations, the mass transfer rate on the drying surface should be determined. The mass flux of evaporated water vapor on the surface is estimated with the formulation given in the literature. The effect of heating temperature, film thickness, and air velocity on drying has been examined to figure out the drying characteristics of the sludge layer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.167-172
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• 2011

A three-dimensional ecological model (EMT-3D) was applied to Tokyo Bay to simulate 4,4'-bis (2-sulfostyryl)biphenyl (DSBP). The simulated results were in good agreement with the observed values, with a correlation coefficient of R=0.8431 and a coefficient of determination of $R^2$=0.7108. The sensitivity analysis indicated that the photolysis rate is the most important factor. Therefore, the parameters must be considered carefully in modeling. The mass balance results showed that the standing stock of DSBP in water and in particulate organic carbon was 621.2 and 19.5 kg, respectively, and the effluent flux to the open sea was 2.63 and 0.055 kg/day, respectively.