• Journal of Food Hygiene and Safety
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• v.30 no.3
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• pp.272-280
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• 2015

A simultaneous official method was developed for the determination of phorate and its metabolites (phorate sulfoxide, phorate sulfone, phorate oxon, phorate oxon sulfoxide, phorate oxon sulfone) in livestock samples. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Phorate and its metabolites were extracted from beef and milk samples with acidified acetonitrile (containing 1% acetic acid) and partitioned with anhydrous magnesium sulfate. Then, the extract was purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/L) for all the analytes into blank extract with $r^2$ > 0.996. For validation purposes, recovery studies were carried out at three different concentration levels (beef 0.004, 0.04 and 0.2 mg/kg; milk 0.008, 0.04 and 0.2 mg/kg, n = 5). The recoveries were within 79.2-113.9% with relative standard deviations (RSDs) less than 19.2% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines. The limit of quantification was quite lower than the maximum residue limit (MRL) set by the Ministry of Food and Drug Safety (0.05 mg/kg). The proposed analytical method was accurate, effective and sensitive for phorate and its metabolites determination and it will be used to as an official analytical method in Korea.

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.131-140
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• 2014

The objective of this study was to develop a simultaneous method of 8 penicillin antibiotics including amoxicillin, ampicillin, cloxacillin, dicloxacillin, nafcillin, oxacillin, penicillin G and penicillin V in meat using LC-MS/MS. The procedure involves solid phase extraction with HLB cartridge and subsequent analysis by LC-MS/MS. To optimize MS analytical condition of 8 compounds, each parameter was established by multiple reaction monitoring in positive ion mode. The chromatographic separation was achieved on a $C_{18}$ column with a mobile phase of 0.05% formic acid and 0.05% formic acid in acetonitrile at a flow rate of 0.2 mL/min for 20 min with a gradient elution. The developed method was validated for specificity, linearity, accuracy and precision in beef, pork and chicken. The recoveries were 71.0~106%, and relative standard deviations (RSD) were 4.0~11.2%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.003~0.008 mg/kg and 0.01~0.03 mg/kg, respectively, that are below maximum residue limit (MRL) of the penicillins. This study also performed survey of residual penicillin antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Penicillins were not found in all the samples except a sample of pork which contained cloxacillin (concentration of 0.08 mg/kg) below the MRL (0.3 mg/kg).

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.123-130
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• 2014

A simultaneous determination was developed for 9 aminoglycoside antibiotics (amikacin, apramycin, dihydrostreptomycin, gentamicin, hygromycin B, kanamycin, neomycin, spectinomycin, and streptomycin) in meat by liquid chromatography tandem mass spectrometry (LC-MS/MS). Each parameter was established by multiple reaction monitoring in positive ion mode. The developed method was validated for specificity, linearity, accuracy, and precision based on CODEX validation guideline. Linearity was over 0.98 with calibration curves of the mixed standards. Recovery of 9 aminoglycosides ranged on 60.5~114% for beef, 60.1~112% for pork and 63.8~131% for chicken. The limit of detection (LOD) and limit of quantification (LOQ) were 0.001~0.009 mg/kg and 0.006~0.03 mg/kg, respectively in livestock products including beef, pork and chicken. This study also performed survey of residual aminoglycoside antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Aminoglycosides were not found in any of the samples.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.1191-1197
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• 2000

In the preliminary study, we investigated the anti-complementary activities of 62 extracts from Korean edible seaweeds. Of those, Pachymeniopsis elliptica showed the highest anti-complementary activity. Therefore, it was purified as follows; i) PE-1 by ethanol precipitation, ii) PE-1-C by ultrafiltration, iii) PE-1-CIV by DEAE-Toyopearl 650C, and iv) PE-1-CIV-ii by Sepharose CL-6B. The purified compound, PE-1-CIV-ii, was the complexed homogeneous polysaccharide (molecular mass: 780 kDa) with 82.9% of anti-complementary activity. Also, it contained a significant amount of sulfate group (30.5%), which indicated it as a sulfated algal polysaccharide. Its structural monosaccharides were galactose (44.3%), 3,6-anhydrogalactose (34.0%), glucose (8.2%), fucose (5.4%), xylose (5.2%) and rhamnose (2.9%). After the treatment of periodate on a sample, a significant decrease in anti-complementary activity was found, which was a characteristic of bioactive polysaccharides. And-tumor activity of PE-1-A, B and C was tested in the sarcoma-180 solid tumor model. The PE-1-C with the largest molecular mass (more than 300 kDa) showed 81% of inhibition on the solid tumors, suggesting that the anti-complementary activity was, at least in part, related to anti-tumor activity. Based upon these results, the purified polysacchardes could be an immunopotentiator in vivo.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.637-648
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• 2009

As the cost of disks decreases, PCs are soon expected to be equipped with a disk of 1TB or more. Assuming that a single person generates 1GB of data per month, 1TB is enough to store data for the entire lifetime of a person. This has lead to the growth of researches on lifelog management, which manages what people see and listen to in everyday life. Although many different lifelog management systems have been proposed, including those based on the relational data model, based on ontology, and based on file systems, they have all advantages and disadvantages: Those based on the relational data model provide good query processing performance but they do not support complex queries properly; Those based on ontology handle more complex queries but their performances are not satisfactory: Those based on file systems support only keyword queries. Moreover, these systems are lack of support for lifelog group management and do not provide a convenient user interface for modifying and adding tags (metadata) to lifelogs for effective lifelog search. To address these problems, we propose a lifelog management system based on the relational data model. The proposed system models lifelogs by using the relational data model and transforms queries on lifelogs into SQL statements, which results in good query processing performance. It also supports a simplified relationship query that finds a lifelog based on other lifelogs directly related to it, to overcome the disadvantage of not supporting complex queries properly. In addition, the proposed system supports for the management of lifelog groups by providing ways to create, edit, search, play, and share them. Finally, it is equipped with a tagging tool that helps the user to modify and add tags conveniently through the ion of various tags. This paper describes the design and implementation of the proposed system and its various applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.1-7
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• 2017

Cobalt silicide was used as a counter electrode in order to confirm its reliability in dye-sensitized solar cell (DSSC) devices. 100 nm-Co/300 nm-Si/quartz was formed by an evaporator and cobalt silicide was formed by vacuum heat treatment at $700^{\circ}C$ for 60 min to form approximately 350 nm-CoSi. This process was followed by etching in $80^{\circ}C$-30% $H_2SO_4$ to remove the cobalt residue on the cobalt silicide surface. Also, for the comparison against Pt, we prepared a 100 nm-Pt/glass counter electrode. Cobalt silicide was used for the counter electrode in order to confirm its reliability in DSSC devices and maintained for 0, 168, 336, 504, 672, and 840 hours at $80^{\circ}C$. The photovoltaic properties of the DSSCs employing cobalt silicide were confirmed by using a simulator and potentiostat. Cyclic-voltammetry, field emission scanning electron microscopy, focused ion beam scanning electron microscopy, and energy dispersive spectrometry analyses were used to confirm the catalytic activity, microstructure, and composition, respectively. The energy conversion efficiency (ECE) as a function of time and ECE of the DSSC with Pt and CoSi counter electrodes were maintained for 504 hours. However, after 672 hours, the ECEs decreased to a half of their initial values. The results of the catalytic activity analysis showed that the catalytic activities of the Pt and CoSi counter electrodes decreased to 64% and 57% of their initial values, respectively(after 840 hours). The microstructure analysis showed that the CoSi layer improved the durability in the electrolyte, but because the stress concentrates on the contact surface between the lower quartz substrate and the CoSi layer, cracks are formed locally and flaking occurs. Thus, deterioration occurs due to the residual stress built up during the silicidation of the CoSi counter electrode, so it is necessary to take measures against these residual stresses, in order to ensure the reliability of the electrode.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.545-552
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• 1998

This study was undertaken to clarify the effects of electrical stimulation on the biochemical properties of plaice sarcoplasmic reticulum and myofibrils at early period of death. The plaices were electrically stimulated (110V/60 Hz) In sea water bath for 15, 35, and 60 seconds, and killed instantly by spiking at the head. Killed samples were investigated for the changes in $Ca^{2+}$-ATPase activity of FSR (fragmented sarcoplasmic reticulum), LSR (light SR), HSR (heavy SR), and SDS-PAGE pattern of FSR. $Ca^{2+}$-ATPase activity of FSR increased until $45^{\circ}C$ and inactivated over $50^{\circ}C$. $Ca^{2+}$-ATPase activity of FSR remarkably decreased according to the duration of electrical stimulation. Myofibrillar $Mg^{2+}$-ATPase activity of electrically stimulated plaices in the presence of $Ca^{2+}$ was higher than that of sample instantly killed by spiking. $Mg^{2+}$-ATPase activity of myofibrils increased by electrical stimulation and the activity decreased during storage at $5^{\circ}C$. Myofibrillar $Mg^{2+}$-ATPase activity in sample killed by spiking was not affected by $Ca^{2+}$ ion. Myofibrillar $Mg^{2+}$-ATPase activity of electrically stimulated sample in the absen-re of $Ca^{2+}$ decreased during storage at $5^{\circ}C$, whit $Mg^{2+}$-ATPase activity in unstimulated sample did not show any change. $Ca^{2+}$-sensitivity of myofibrils showed no differences between electrically stimulated sample and sample killed by spiking, and the was no change during at $5^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1133-1138
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• 2006

Smilax china root has been used as traditional medicinal remedy in China and Korea and reported to have various biological activities such as anti-inflammatory, antimutagenic and antimicrobial activities. In this study, the possibility of development as natural antioxidants of Smilax china root extracts was investigated. For the evaluation of antioxidant activity, aqueous- and 25% EtOH extract from Smilax china root were prepared and six different evaluation assay methods, i.e., measurement of total phenolics, radical scavenging effects on 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide (NO) and nitrite $(NO_2)$, reducing power, and inhibitory effect on tyrosinase activity, were used. The total phenolics content of two extracts was high as the level of 36 mg of gallic acid equivalent per 1 g of dried sample tested. The radical scavenging activities of ethanol extract toward DPPH and NO were better than those of aqueous extract (p<0.05). The $NO_2$ scavenging activity of both extracts showed the highest value at pH 1.2 (98%). Especially, the $NO_2$ scavenging activities of EtOH extract were significantly stronger than those of aqueous one at pH 4.2 (51%) and pH 6.0 (32%), respectively. In the reducing power test, both extracts revealed higher ferric ion reducing activity than known antioxidant, vitamin C at the level of $0.05\sim0.1mg/mL$ (p<0.01). The 1 mL of aqueous and 25% EtOH extract showed effective inhibition activity on tyrosinase activity as 45% and 53%, respectively. Therefore, these results suggest that two extracts from Smilax china root may serve as useful natural antioxidants.

• Journal of the Korean Child Neurology Society
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• v.26 no.4
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• pp.205-209
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• 2018

Purpose: Several studies have shown that magnesium plays an important role in modulating N-methyl-D-aspartate (NMDA)-related seizures by blocking NMDA ion channel receptors. Clinicians usually measure total serum magnesium levels instead of biologically active ionized magnesium levels. We compared the serum ionized magnesium ($iMg^{2+}$) level between epileptic children with and without a history of fever-triggered seizure (FTS). Methods: All epileptic children who visited the outpatient clinic or pediatric emergency department at Korea University Guro Hospital between January 2015 and July 2017 were included. Only epileptic children aged 1-8 years who were newly diagnosed within 2 years were included. Results: There were 12 children with FTS and 16 without FTS. Median serum $iMg^{2+}$ level was 0.93 (0.85-1.14, quartile) mEq/L. Serum $iMg^{2+}$ level was significantly lower in epileptic children with FTS (0.86 mEq/L) compared to those without FTS (1.10 mEq/L) (P=0.005). No difference was noted in clinical variables between the two groups. Lower serum $iMg^{2+}$ level significantly increased the risk of having FTS in epileptic children based on multivariable logistic regression analysis (odds ratio [OR]=0.028). Conclusion: Serum $iMg^{2+}$ level was significantly lower in epileptic children with FTS than in those without FTS. Measurement of biologically active serum $iMg^{2+}$ level could be considered in epileptic children with recurrent FTS. A large-scale prospective study is warranted.

• Resources Recycling
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• v.28 no.5
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• pp.60-67
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• 2019

A valuable metal recovery from waste resources such as spent rechargeable secondary batteries is of critical issues because of a sharp increase in the amount of waste resources. In this context, it is necessary to research not only recycling waste lithium-ion batteries (LIBs), but also reusing valuable metals (e.g., Li, Co, Ni, Mn etc.) recovered from waste LIBs. In particular, the lithium hydroxide ($LiOH{\cdot}xH_2O$), which is of precursors that can be prepared by the recovery of Li in waste LIBs, can be reused as a catalyst, a carbon dioxide absorbent, and again as a precursor for cathode materials of LIB. However, most studies of recycling the waste LIBs have been focused on the preparation of lithium carbonate with a recovery of Li. Herein, we show the preparation of high purity lithium hydroxide powder along with the precipitation process, and the systematic study to find an optimum condition is also carried out. The lithium carbonate, which is recovered from waste LIBs, was used as starting materials for synthesis of lithium hydroxide. The optimum precipitation conditions for the preparation of LiOH were found as follows: based on stirring, reaction temperature $90^{\circ}C$, reaction time 3 hr, precursor ratio 1:1. To synthesize uniform and high purity lithium hydroxide, 2-step precipitation process was additionally performed, and consequently, high purity $LiOH{\cdot}xH_2O$ powder was obtained.