• Korean Journal of Food Science and Technology
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• v.43 no.5
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• pp.532-536
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• 2011

The internal standard method using ion chromatography combined with tandem mass spectrometry (IC-MS/MS) for quantifying perchlorate in different types of food was established. Because the presence of ions and other biomolecules in matrices usually interrupts accurate determination of perchlorate, it is necessary to develop efficient, reproducible method to determine perchlorate concentrations in food. In this study, the internal standard method was compared with the external standard method to determine perchlorate concentrations in standard samples. The obtained method detection limit (MDL) for perchlorate was 0.005 ${\mu}g/L$ for bottled water, 0.12 ${\mu}g/L$ for milk, 0.27 ${\mu}g/kg$ for rice, 0.16 ${\mu}g/kg$ for vegetables, and 0.07 ${\mu}g/kg$ for seaweed, respectively. The limit of quantitation (LOQ) was calculated by multiplying the MDL by 7. The recoveries of perchlorate from food samples spiked with perchlorate ranged from 98 to 105% and their percent relative standard deviation (%RSD) levels were <20%. This method was successfully applied for the quantitative determination of perchlorate in various kinds of food.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.496-523
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• 2018

The objective of this study is to evaluate the economic feasibility of two fast pyrolysis and biooil upgrading (FPBU) plants including feed drying, fast pyrolysis by fluidized-bed, biooil recovery, hydro-processing for biooil upgrading, electricity generation, and wastewater treatment. The two FPBU plants are Case 1 of an FPBU plant with steam methane reforming (SMR) for $H_2$ generation (FPBU-HG, 20% yield), and Case 2 of an FPBU with external $H_2$ supply (FPBUEH, 25% yield). The process flow diagrams (PFDs) for the two plants were constructed, and the mass and energy balances were calculated, using a commercial process simulator (ASPEN Plus). A four-level economic potential approach (4-level EP) was used for techno-economic analysis (TEA) under the assumption of sawdust 100 t//d containing 40% water, 30% equity, capital expenditure equal to the equity, $H_2$ price of $1050/ton, and hydrocarbon yield from dried sawdust equal to 20 and 25 % for Case 1 and 2, respectively. TCI (total capital investment), TPC (total production cost), ASR (annual sales revenue), and MFSP (minimum fuel selling price) of Case 1 were $22.2 million, $3.98 million/yr, $4.64 million/yr, and $1.56/l, respectively. Those of Case 2 were $16.1 million, $5.20 million/yr, $5.55 million/yr, and $1.18/l, respectively. Both ROI (return on investment) and PBP (payback period) of Case 1(FPBU-HG) and Case 2(FPBU-EH) were the almost same. If the plant capacity increases into 1,500 t/d for Case 1 and Case 2, ROI would be improved into 15%/yr.

• Analytical Science and Technology
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• v.25 no.4
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• pp.236-241
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• 2012

There are many industrial factories in the central Nakdong river basin and have been occurred water pollution accidents by hazardous chemicals such as phenol, 1,4-dioxane and perchlorate. In this study, ten compounds of semi-volatile organic compounds (SVOCs) (dichlorvos, toluene-2,4-diisocyanate, 4,4'-methylenedianiline, 4,4'-methylenebis (2-chloroaniline), diethyl phthalate, di-n-butyl phthalate, butyl benzyl phthaltate, bis (2-ethylhexyl) adipate, benzophenone, 4,4'-bisphenol A) of hazardous chemicals which may be potentially discharged into the Nakdong river, were determined by gas chromatography-mass spectrometry (GC-MS) with disk-type solid-phase extraction. Accuracy and precision were in the range of 75.6~110.5%, and 4.6~12.7%, respectively and recovery was in the range of 72.4~127.9%. Three compounds (bis (2-ethylhexyl)adipate, benzophenone, 4,4'-bisphenol A) were detected in industrial wastewater such as wastewater treatment plants (WWTPs) and wastewater discharge facilities in the Nakdong River basin.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.263-268
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• 2019

Methanol is a toxic alcohol used in various products such as antifreeze, detergent, disinfectant and industrial solvent. In the human body, methanol is oxidized to formaldehyde and formic acid, which can lead to metabolic acidosis, optic nerve impairment, and death. In this study, the methanol levels in detergents (n=191) and rinse aids (n=13) were analyzed by gas chromatography-headspace-mass spectrometry (GC-HS-MS). Limit of detection was 1.09 mg/kg, accuracy and precision were 91.1-97.9% and <10%, and it was suitable for quantitative analysis. This analysis method was simple and fast with a higher recovery rate than the conventional MFDS (Ministry of Food and Drug Safety) method of diluting the sample in water and putting it in a headspace vial.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.570-577
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• 2000

A method was presented for determination of bisphenol F(BPF), bisphenol A(BPA), bisphenol F diglycidyl ether(BFDGE) and bisphenol A diglycidyl ether(BADGE) in 3 aqueous-based food simulants (water, 4% acetic acid, 20% ethanol) by reverse-phase high performance liquid chromatography(RP-HPLC)with fluorescence detection and gas chromatography with mass selective detection(GC/MSD). All the calibration lines in the range of $5{\sim}800\;{\mu}g/L$ had correlation coefficients greater than 0.9998 and detection limits of less than $1.2\;{\mu}g$ bisphenols/L. Precision at $200\;{\mu}g/L$ was under 3.1%. Recoveries of bisphenols simultaneously spiked to aqueous food simulants exceeded 95% for BPF and BPA but about 80% for BFDGE and BADGE. However, recoveris of BFDGE and BPADGE respectively spiked increased upto 95%. Detection limits in recovery test were less than $0.40\;{\mu}g$ bisphenols/L. In migration test bisphenols were determined by RP-HPLC coupled with confirmation by GC/MSD. Can coatings of epoxy phenol, modified epoxy, epoxy ester phenol and thermoset vinyl were exposed to the 3 aqueous food simulants. BPF, BFDGE and BADGE were not detected in all the can coatings but BPA was detected in 4% acetic acid and 20% ethanol in all the can coatings except modified epoxy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.2
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• pp.115-132
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• 1992

This study was conducted to clarify the distribution pattern of macrobenthic soft-bottom dwelling animals near the shellfish farming ground in Chinhae Bay, Korea Sampling was seasonally performed with van Veen grab$(0.1m^2)$ from October 1990 to July 1991. Benthic animals collected during the study comprised 107 species which amounted to 6,978 individuals: 52 species from polychaetes$(48.6\%)$, 34 species from crustaceans$(31.8\%),$ 14 species from molluscs$(13.1\%)$ and 7 species from other faunal groups$(6.5\%)$. The dominant species were four polychaetes and one amphipod: Lumbrineis longifolia, Capitella capitate, Mediomastus sp., Sigambra tentaculata and Erictonius pugnax. The study area could be divided into 3 regions based on the faunal similarity which was closely related to the content of organic matter in the surface sediment. The benthic community located near the shellfish farming ground showed large spatial and seasonal variations in species diversity and evenness in contrast to the stable values off the farming area. The oxygen deficient water mass below 2 ml/l In thi bottom layer during the summer stressed and depauperated the benthic community in the autumn of 1990. However, the benthic community did recover during the winter. It is postulated that the cyclic phenomenon of summer mortality followed by winter recovery may be a common characteristic in benthic communities subjected to a high level of organic pollution.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.6
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• pp.521-537
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• 2012

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2011. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) Research trends of thermal and fluid engineering have been surveyed as groups of fluid machinery and fluid flow, thermodynamic cycle, and new and renewable energy. Various topics were presented in the field of fluid machinery and fluid flow. Research issues mainly focused on the rankine cycle in the field of thermodynamic cycle. In the new and renewable energy area, researches were presented on geothermal energy, fuel cell, biogas, reformer, solar water heating system, and metane hydration. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer, nanofluids and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer above liquid helium surface in a cryostat, methane hydrate formation, heat and mass transfer in a liquid desiccant dehumidifier, thermoelectric air-cooling system, heat transfer in multiple slot impinging jet, and heat transfer enhancement by protrusion-in-dimples. In the area of pool boiling and condensing heat transfer, researches on pool boiling of water in low-fin and turbo-B surfaces, pool boiling of R245a, convective boiling two-phase flow in trapezoidal microchannels, condensing of FC-72 on pin-finned surfaces, and natural circulation vertical evaporator were actively performed. In the area of nanofluids, thermal characteristics of heat pipes using water-based MWCNT nanofluids and the thermal conductivity and viscosity were measured. In the area of industrial heat exchangers, researches on fin-tube heat exchangers for waste gas heat recovery and Chevron type plate heat exchanger were implemented. (3) Refrigeration systems with alternative refrigerants such as $CO_2$, hydrocarbons, and mixed refrigerants were studied. Heating performance improvement of heat pump systems were tried applying supplementary components such as a refrigerant heater or a solar collector. The effects of frost growth were studied on the operation characteristic of refrigeration systems and the energy performance of various defrost methods were evaluated. The current situation of the domestic cold storage facilities was analyzed and the future demand was predicted. (4) In building mechanical system fields, a variety of studies were conducted to achieve effective consumption of heat and maximize efficiency of heat in buildings. Various researches were performed to maximize performance of mechanical devices and optimize the operation of HVAC systems. (5) In the fields of architectural environment and energy, diverse purposes of studies were conducted such as indoor environment, building energy, and renewable energy. In particular, renewable energy and building energy-related researches have mainly been studied as reflecting the global interests. In addition, various researches have been performed for reducing cooling load in a building using spot exhaust air, natural ventilation and energy efficiency systems.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.140-147
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• 2019

An analytical method was developed for the determination of quinoxyfen in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted with 1% acetic acid in acetonitrile and water was removed by liquid-liquid partitioning with $MgSO_4$ (anhydrous magnesium sulfate) and sodium acetate. Dispersive solid-phase extraction (d-SPE) cleanup was carried out using $MgSO_4$, PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed by using LC-MS/MS in positive mode with MRM (multiple reaction monitoring). The matrix-matched calibration curves were constructed using six levels ($0.001-0.25{\mu}g/mL$) and the coefficient of determination ($R^2$) was above 0.99. Recovery results at three concentrations (LOQ, 10 LOQ, and 50 LOQ, n=5) were in the range of 73.5-86.7% with RSDs (relative standard deviations) of less than 8.9%. For inter-laboratory validation, the average recovery was 77.2-95.4% and the CV (coefficient of variation) was below 14.5%. All results were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for quinoxyfen determination in agricultural commodities. This study could be useful for the safe management of quinoxyfen residues in agricultural products.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.290-297
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• 2017

The purpose of this study was developed for the determination of tridemorph in agricultural commodities samples. Tridemorph residues in samples were extracted with acetonitrile, partitioned with saline water, and then purified using and aminopropyl ($NH_2$) SPE catridge. The purified samples were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Matrix-matched calibration curves were linear over the calibration ranges (0.005~2.5 ng) into a blank extract with $r^2$ > 0.999. The limits of detection and quantification were 0.001 and 0.005 mg/kg, respectively. The average recovery ranged between 75.9% and 103.7% at different concentration levels (LOQ, 10 LOQ, 50 LOQ, n = 5) with relative standard deviations (RSDs) less than 9.0%. An interlaboratory study was conducted to validate the method by Korea Advanced Food Research Institute. The average recovery ranged between 87.0% and 109.2% at different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$, n = 5) with relative standard deviations (RSDs) less than 8.0%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL40, 2003) and Food Safety Evaluation Department guidelines (2016). The results prove that the developed analytical methods is accurate, effective and sensitive for tridemorph determination.

• Korean Journal of Remote Sensing
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• v.14 no.4
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• pp.353-365
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• 1998

Light absorption coefficient per unit mass of particles, i.e., specific absorption coefficient, is important as one of the main parameters in developing algorithms for ocean color remote sensing. Specific absorption coefficient of chlorophyll ($a^*_{ph}$) and suspended sediment ($a^*_{ss}$) were analyzed with a spectrophotometer using the "wet filter technique" and "Kishino method" for the seawater collected in the Yellow and Mediterranean Sea. An improved data-recovery method for the filter technique was also developed using spectrum slopes. This method recovered the baselines of spectrum that were often altered in the original methods. High $a^*_{ph}({lambda})$ values in the oligotrophic Mediterranean Sea and low values in the Yellow Sea were observed, ranging 0.01 to 0.12 $m^2$/mg at the chlorophyll maximum absorption wavelength of 440 nm. The empirical relationship between $a^*_{ph}$(440nm) and chlorophyll concentrations () was found to fit a power function ($a^*_{ph}$=0.039 $^{-0.369}$), which was similar to Bricaud et al. (1995). Absorption specific coefficients for suspended sediment ($a^*_{ss}$) did not show any relationship with concentrations of suspended sediment. However, an average value of $a^*_{ss}$ ranging 0.005 - 0.08 $m^2$/g at 440nm, was comparable to the specific absorption coefficient of soil (loess) measured by Ahn (1990). The morepronounced variability of $a^*_{ss}$ than $a^*_{ph}$ was determined from the variable mixing ratio values between particulate organic matter and mineral. It can also be explained by a wide size-distribution range for SS which were determined by their specific gravity, bottom state, depth and agitation of water mass by wind in the sea surface.