• Analytical Science and Technology
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• v.25 no.1
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• pp.25-32
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• 2012

Isotope dilution mass spectrometry (ID-MS) based on liquid chromatography tandem mass spectrometry (LC/MS/MS) was developed for the accurate determination of sorbic acid in tea-drink. An isotope analogue of sorbic acid, $^{13}C_2$-sorbic acid, was obtained by custom synthesis. MS was operated in the negative mode with selected reaction monitoring (SRM) mode of $[M-H]^-$ ${\rightarrow}$ $[M-CO_2H]^-$ channel at m/z 111 ${\rightarrow}$ 67 for sorbic acid and at m/z 113 ${\rightarrow}$ 68 for its isotope analogue. Chromatographic separation was accomplished with a C18 column and an isocratic mobile phase of 55% of 50 mM ammonium acetate (pH 4.5) and 45% of methanol. Homogeneous reference materials were prepared for validation of this method, including repeatability and reproducibility tests, by fortifying tea-drink with sorbic acid in our laboratory. Repeatability and reproducibility studies showed that the ID-LC/MS method is a reliable and reproducible method which provides less than 3.8% of relative standard deviation (RSD) for the analysis of sorbic acid.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.109-116
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• 2011

To measure the traffic pollutants with high temporal and spatial resolution under real conditions a mobile emission laboratory (MEL) was designed and built in KIST with close-cooperation with KIMM and Yonsei university. The equipment of the mini-van provides gas phase measurements of CO, NOx, $CO_2$, THC (Total hydrocarbon) and number density & size distribution measurements of fine and ultra-fine particles by a fast mobility particle sizer (FMPS) and a condensation particle counter (CPC). The inlet sampling port above the bumper enables the chasing of different type of vehicles. This paper introduces the construction and technical details of the MEL and presents data from the car chasing experiment of diesel and CNG city bus. The dilution ratio was increased rapidly according to the chasing distance. Most particles from the diesel city bus were counted under 300 nm and the peak concentration of the particles was located between 40-60 nm. However, the most particles from the CNG city bus were nano particle counted under 50 nm.

• Journal of the Korean Society of Tobacco Science
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• v.7 no.2
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• pp.179-188
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• 1985

From the combination of cigarette papers, tipping papers and plug wrapping papers, whose physical properties and effect of cigarette smoke dilution were studied. The result obtained from this study are as follows. Envelop ventilation (Env-V'R) cigarettes used high porous cigarette papers showed less changes of unencapsulated pressure drop VPD) compared to tip ventilation (Tip-VR) cigarettes. Higher cigarette paper porosity increased, more decreased the WD of cigarette by Tip-VR. With cigarette length shortening, the UPD or VR changed a little in Tip-VR cigarette, while changed very much in Env-VR cigarettes. The ratio of nicotine/tar was higher in Env-VB cigarettes than in Tip-VR cigarettes, and CO/nicotine value of the former was lower than those of the later. The effect of Tip-VR cigarettes on the delivery reduction of tar and nicotine was more effective compared to Env-VR cigarettes and the reduction prefer Env-VR cigarettes to Tip-VR cigarettes in CO delivery. From the results investigated above it was noted that each defect appeared in the Tip-VR and the Env-VR cigarettes could be complemented by the combination of them.

• Ocean and Polar Research
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• v.25 no.1
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• pp.53-62
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• 2003

Inductively coupled plasma mass spectrometry (ICP-MS) is useful instrument for determining abundance of rare earth elements, due to very low detection limits and rapid data acquisition. In this article, two methods are used for decomposition of alkaline rocks; close vessel acid digestion and $Na_2Co_3$ fusion. The two analytical results show good agreements. Considering total dissolved solids and detection limits, the most adequate dilution factor is 5,000 times. Polyatomic ion interferences during analysis can give rise to Inaccuracies. After correction from oxide and hydroxide interference, the analytical result show 20-30% decrease for Gd and Tm, 10-20% decrease for Tb and Er. In comparing the analytical results from KORDI with other institutes, most rare earth elements abundance show good agreements except Lu.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.9-18
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• 2008

The fundamental objects of the Korean Grand Canal (KGC) Project are the rehabilitation(or restoration) of river corridor ecology, improvement of river water quality, reduction of flood damages, countermeasure of the huge rise in energy price and the high discharge of $CO_2$ due to the vast use of energy for highway logistics. The other important objects, like an increase of water in the river channel, are to provide people with the pleasure of seeing the water and intimacy (touchiness) with it, an increase of flood controllability, effects of dilution of river pollutants, dredging out sedimentary pollutant from the river bottom, the function of infrastructure to pare down the logistics (distribution) costs, and the opportunity to expand tourism. These kinds of fundamental concepts must be evaluated as future values in Korea and elsewhere.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2019.08a
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• pp.144-145
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• 2019

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.8
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• pp.632-638
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• 2013

This paper describes on the flame stability and combustion instability of coal derived synthetic gas especially for gases of Buggenum IGCC in Netherlands and Taean IGCC in Korea. These combustion characteristics were observed by conducting ambient-pressure elevated-temperature combustion tests in GE7EA model combustor when varying heat input and nitrogen dilution ratio. Flame stability map is plotted according to the flame structure by dividing all regimes into six, and only regime I and II are identified to be stable. Both syngases of Taean and Buggenum with nitrogen integration corresponds to regime II in which syngas burnt stably and flame coupled with outer recirculation flow. Stable regime of Buggenum is larger than that of Taean when considering only $H_2$/CO ratio due to higher content of hydrogen. However, when considering nitrogen dilution, syngas of Taean is burnt more stably than that of Buggenum since more nitrogen in Buggenum has negative effect on the stability of flame.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.689-699
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• 2022

The Ssangjeon tungsten deposit is located within the Yeongnam Massif. Within the area a number of hydrothermal quartz veins were formed by narrow open-space filling of parallel and subparallel fractures in the metasedimentary rocks as Wonnam formation, Buncheon granite gneiss, amphibolite and/or pegmatite. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz vein; stage II, barren quartz vein) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages (early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of arsenopyrite with pyrite; middle, characterized by introduction of wolframite and scheelite with Ti-Fe-bearing oxides and base-metal sulfides; late, marked by Bi-sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥370℃) and later lower temperatures (≈170℃) from H₂O-CO₂-NaCl fluids with salinities between 18.5 to 0.2 equiv. wt. % NaCl of Ssangjeon hydrothermal system. The relationship between salinity and homogenization temperature indicates a complex history of boiling, fluid unmixing (CO₂ effervescence), cooling and dilution via influx of cooler, more dilute meteoric waters over the temperature range ≥370℃ to ≈170℃. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Ssangjeon hydrothermal system with increasing paragenetic time.

• Economic and Environmental Geology
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• v.55 no.2
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• pp.171-181
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• 2022

The Geochang Au-Ag deposit is located within the Yeongnam Massif. Within the area a number of hydrothermal quartz and calcite veins were formed by narrow open-space filling of parallel and subparallel fractures in the granitic gneiss and/or gneissic granite. Mineral paragenesis can be divided into two stages (stage I, ore-bearing quartz vein; stage II, barren calcite vein) by major tectonic fracturing. Stage I, at which the precipitation of major ore minerals occurred, is further divided into three substages (early, middle and late) with paragenetic time based on minor fractures and discernible mineral assemblages: early, marked by deposition of pyrite with minor pyrrhotite and arsenopyrite; middle, characterized by introduction of electrum and base-metal sulfides with minor sulfosalts; late, marked by hematite with base-metal sulfides. Fluid inclusion data show that stage I ore mineralization was deposited between initial high temperatures (≥380℃ ) and later lower temperatures (≤210℃ ) from H₂O-CO₂-NaCl fluids with salinities between 7.0 to 0.7 equiv. wt. % NaCl of Geochang hydrothermal system. The relationship between salinity and homogenization temperature indicates a complex history of boiling, fluid unmixing (CO₂ effervescence), cooling and dilution via influx of cooler, more dilute meteoric waters over the temperature range ≥380℃ to ≤210℃. Changes in stage I vein mineralogy reflect decreasing temperature and fugacity of sulfur by evolution of the Geochang hydrothermal system with increasing paragenetic time. The Geochang deposit may represents a mesothermal gold-silver deposit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.7
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• pp.1039-1046
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• 2002

Co-flow axisymmetric laminar premixed flame of methane was used to study the influence of air temperature and $N_2$ addition on the flame structure, temperature field and emission characteristics. OH 2-D images and temperatures along the centerline were measured experimentally by PLIF and CARS techniques respectively to observe the influences of dilution and thermal effects of $N_2$ in the gas mixture. Also, the concentration of NOx was measured at each condition by gas analyser to see the suppression effect of N2 addition on NOx emissions. It was found that OH concentrations distribute widely as air temperature goes higher, while the effect of $N_2$ addition is not significant. But $N_2$ addition highly contributes to the flame front and NOx emissions which was argued to be due to the reduction of flame temperature. In accordance with experimental study, numerical simulation using CHEMKlN code was carried out to compare the temperature results with those acquired by CARS measurement, and we could find that there is good agreement between those results.