• Korean Journal of Pharmacognosy
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• v.45 no.2
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• pp.113-120
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• 2014

Generally, Gwakhyangjeonggi-san has been used for treatment of diarrhea-predominant irritable bowel syndrome. In this study, an ultra-performance liquid chromatography-electrospray ionization-mass spectrometer method was established for the simultaneous quantification of marker compounds 1-20 in Gwakhyangjeonggi-san water extract. All analytes were separated by gradient elution using two mobile phases on a UPLC BEH $C_{18}$ ($100{\times}2.1mm$, $1.7{\mu}m$) column and maintained at $45^{\circ}C$. The injection volume was $2.0{\mu}L$ and the flow rate was 0.3 mL/min with detection at mass spectrometer. Regression equations of the compounds 1-20 were acquired with $r^2$ values ${\geq}0.9950$. The values of limit of detection and quantification of all analytes were 0.01-2.79 ng/mL and 0.03-8.37 ng/mL, respectively. The amounts of the compounds 1-20 in Gwakhyangjeonggi-san water extract were not detected $-3,236.67{\mu}g/g$. The established LC-MS/MS methods will be valuable to improve quality control of traditional herbal formula, Gwakhyangjeonggi-san.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.344-354
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• 1998

This study was conducted to evaluate the MSPD and HPLC method about simultaneous determination for residual synthetic antimicrobials of sixteen species such as sulfonamide etc. in livestock products. Elution solvent used in HPLC was ethylacetate:acetonitrile (4:1), and mobile phases for solvent A and B were water:methanol:acetonit rile:phosphric acid (700:250:50:0.2) and 100% acetonitrile respectively. The detector and absorbency used in HPLC was UV 266 nm. This study showed the reduction effect of 99.1% for organic solvents, 94% for experimental steps, 95% for analytical time and manpower and 98.9% for costs compared with korea food standard method. The average recovery rates for chicken, bovine, pork and milk were 67.7% 96.2%, 67.7%~96.6%, 70.0%~96.2%, and 13.8%~97.8%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3150-3170
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• 2016

In Intelligent Transportation Systems (ITS), logistics distribution and mobile e-commerce, the real-time, accurate and reliable vehicle trajectory prediction has significant application value. Vehicle trajectory prediction can not only provide accurate location-based services, but also can monitor and predict traffic situation in advance, and then further recommend the optimal route for users. In this paper, firstly, we mine the double layers of hidden states of vehicle historical trajectories, and then determine the parameters of HMM (hidden Markov model) by historical data. Secondly, we adopt Viterbi algorithm to seek the double layers hidden states sequences corresponding to the just driven trajectory. Finally, we propose a new algorithm (DHMTP) for vehicle trajectory prediction based on the hidden Markov model of double layers hidden states, and predict the nearest neighbor unit of location information of the next k stages. The experimental results demonstrate that the prediction accuracy of the proposed algorithm is increased by 18.3% compared with TPMO algorithm and increased by 23.1% compared with Naive algorithm in aspect of predicting the next k phases' trajectories, especially when traffic flow is greater, such as this time from weekday morning to evening. Moreover, the time performance of DHMTP algorithm is also clearly improved compared with TPMO algorithm.

• Transactions of Materials Processing
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• v.15 no.2 s.83
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• pp.118-125
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• 2006

API steel is used for line-pipe to transport the oil and natural gas. As the recent trends in the development of API steel are towards the use of larger diameter and thicker plate, many researches have been studied to achieve higher strength, higher toughness and lower yield ratio in API steel. However, the strength of API steel after pipe forming is changed depending on the competition of the Bauschinger effect and work hardening which are affected by the strain history during pipe forming process. So, the purpose of this study is to investigate the influence of microstructure on the Bauschinger effect for API steel. To change the microstructure of API steel we have changed the hot rolling condition and the amounts of V and Cu addition. The compression-tensile test and the microstructure observation by OM and TEM were conducted to investigate the yield strength drop and the correlation between the Bauschinger effect and microstructure of API steel. The experimental results show that the increase of polygonal ferrites volume fraction increases the Baushcinger effect due to the back stress which comes from the increase of mobile dislocation density at polygonal ferrite interior during the compressive deformation. The hot rolling condition was more effective on the Bauschinger effect in API steel than the small amount of V and Cu addition.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.69-78
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• 1993

Contents of heavy metals (Cr, Cu, Zn, Cd, and Pb) in the sediments of Ulsan Bay were investigated by the sequential extraction methods that classifies heavy metals into five types of chemical forms: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. The analyses were determined by using an ICP-MS. Total Cr concentrations in the sediments were in the range of 41.6-96.4, Cu 60.7-680, Zn 189-1954, Cd 33.1-83.4, and Pb 138-567 mg/kg. Results of sequential fractionation indicates that relatively high proportion ( ~44%) of Cu is associated with organic matter. A large proportion of Pb is associated with three types of chemical forms: Fe-Mn oxides, organic matter, and residual. There were significant correlation in concentrations between the exchangeable components and total organic carbons. The heavy metals In the residual phase cannot be easily released to the environment since these are bound to the crystal lattice. But, reducible and organic Phases con a significant amount of most heavy metals. Therefore, there is Potential dancer of a substantial amount of metals becoming chemically mobile with environmental changes.

• Journal of Environmental Science International
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• v.14 no.4
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• pp.445-449
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• 2005

A simple and sensitive analytical method based on RP-HPLC with UV detector$(225{\cal}nm)$ and mobile phases using $0.1{\%}$ phosphoric acid and acetonitrile was developed for simultaneous determination of quinclorac, bentazone, 2,4-D, bensulfuron-methyl, dymuron, capropamide, pencycuron, ethofenprox. This method was resulted in recovery of $78{\~}96{\%}$ with RSD $3.3{\~}7.5{\%}$, LODs $0.12{\~}0.84$ and LOQs $0.34{\~}1.20{\cal}mg/L$. Calibration curves were linear with r of $0.9995{\~}0.9999$.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.490-494
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• 1991

The ${\beta} to {\alpha}$ phase transition in silver iodide is studied with the (N, V, E) and (N, P, T) molecular dynamics (MD) method. In experiments, the phase transition temperature is 420 K. Upon heating of ${\beta}$ form, the iodine ions undergo hcp to bcc transformation and silver ions become mobile. MD simulations for the ${\beta}$ and ${\alpha}$ phases are carried out at several temperatures and the radial distribution functions (rdf) are obtained at those temperatures in the (N, V, E) ensemble. But the phase transition is not found in our calculation. Next the phase transition is studied with the (N, P, T) MD and we find some evidences of phase transition. At 3 Kbars and 2 Kbars the phase transition temperatu re is about 300 K. For 3.55 Kbars, the phase transition is higher (420 K) than the low pressure case. The phase transition temperature is somewhat dependent on the pressure in our calculations.

• Korean Journal of Materials Research
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• v.31 no.7
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• pp.403-408
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• 2021

Various surface colors are predicted and implemented using the interference color generated by controlling the thickness of nano-level diamond like carbon (DLC) thin film. Samples having thicknesses of up to 385 nm and various interference colors are prepared using a single crystal silicon (100) substrate with changing processing times at low temperature by plasma-enhanced chemical vapor deposition. The thickness, surface roughness, color, phases, and anti-scratch performance under each condition are analyzed using a scanning electron microscope, colorimeter, micro-Raman device, and scratch tester. Coating with the same uniformity as the surface roughness of the substrate is possible over the entire experimental thickness range, and more than five different colors are implemented at this time. The color matched with the color predicted by the model, assuming only the reflection mode of the thin film. All the DLC thin films show constant D/G peak fraction without significant change, and have anti-scratch values of about 19 N. The results indicate the possibility that nano-level DLC thin films with various interference colors can be applied to exterior materials of actual mobile devices.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.453-459
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• 2006

D-tryptophan and N-CBZ-D-phenylalanine were separated using ionic liquid as additives for the mobile phase in high performance liquid chromatography (HPLC). The ionic liquid of 1-butyl-3- methylimidazolium tetrafluoroborate (${[BMIm]}^+{[BF_4]}^-$) was used. Mobile phases were 65％, 70％, and 80％ methanol in water with addition of different concentrations (0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, and 15.0 mmol/L) of the ionic liquid. The experiments were performed on stainless steel column, $3.9{\times}300mm$ i.d., packed with $15{\mu}m$ octadecyl-bonded silica gel at laboratory.The retention factor of D-tryptophan was not negligibly changed while that of N-CBZ-D-phenylalanine was decreased. The resolution between the two components were affected by the contents of methanol and ionic liquid in the mobile phase. With the small content of methanol and the high concentration of ionic liquid, the resolution was improved.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.181-186
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• 2005

This experiment was conducted to know the appropriate methods for extraction and determination of rutin contained buckwheat plants. The efficient HPLC analytical condition of rutin contained buckwheat plants was developed. The gradient elution employed a $250mm\times4.6mm$ i.d. Tosoh ODS 120T column. The gradient system was used two mobile phases. A gradient elution was performed with mobile phase A, consisting of $2\%$ Acetic $acid-45\%$ Acetonitrile, and mobile phase B, comprising $2\%$ aqueous acetic acid, and delivered at a flow rate of 1mL/min as follows: 0-18 min, $50-100\%$ A; 18-20 min, $100-50\%$ A; 20-22 min, $50\%$ A. The UV detection wavelength was set at 355 nm. The limit of detection (LOD) for rutin standard compound was 20 ng/mL. And, the higher content of rutin in the extracts was obtained by $80^{\circ}C$ reflex extraction for 120 min. from plants of buckwheat using ethanol.