• Journal of the Korean Chemical Society
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• v.42 no.3
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• pp.266-276
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• 1998

Cholesterol supersaturation in bile, which causes gallstone formation, is the result of low bile acid secretion or high cholesterol secretion. The quantitative analysis of cholesterol, bile acids and sterols which are precursors of cholesterol have been used to examine the changes in bile component. We described a simple, sensitive and reproducible method for simultaneous determination of cholesterol, five bile acids and seven sterols in human bile juices and gallstones by capillary column gas chromatography-mass spectrometry (GC/MS). Clinical samples were hydrolyzed by alcoholic KOH, extracted twice (pH 14 and 1) and derivatized to trimethylsilyl (TMS) ether with $MSTFA/NH_4I$ (N-methyl-N-trimethylsilyltrifluoroacetamide/ammonium iodide) mixture in order to be detected on the GC/MS. The good quality control data were obtained through within-a-day and day-to-day test (RSD values were 1.72-13.79, 0.68-14.10, respectively) and the recovery range of them was 73.56-96. 95 Using this method, biliary and gallstone compositions in the patients with intrahepatic stones were analyzed. The amounts and its relative distribution of cholesterol, bile acids and sterols showed different pattern in bile juices and gallstones.

• Analytical Science and Technology
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• v.33 no.3
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• pp.115-124
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• 2020

Marker pens belong to school things that are controlled by the regulation system called safety confirmation under special act on the safety of products for children with the formaldehyde criteria of 20 mg/kg. With nine marker pens available commercially, formaldehyde in marker pen ink was analyzed by present test standard where marking on a fabric swatch with a pen and extracting the swatch in water and derivatization with Nash reagent followed by UV/Vis spectrophotometeric measurement (Nash-UV/Vis method), giving not detected results or a false positive result in case of a colored water extract. However, the contents of formaldehyde in ink of nine marker pens were determinded to range between 3.2 ~ 93.2 mg/kg with three results above the safety criteria of 20 mg/kg by HPLC/DAD measurements on DNPH derivatives of formaldehyde (DNPH-HPLC/DAD method) in ink dissolved directly in water using an ultrasonic bath. Therefore, the DNPH-HPLC/DAD method with the extraction of ultrasonic dissolving ink in water is proposed as a proper method for analyzing formaldehyde in ink. The proposed method has advantages of lower detection limit and accuracy with colored extracts as well as a simple and fast extraction. The accuracy and precision of this method was estimated to be 90.1 ~ 105.4 % and 0.6 ~ 3.3 %, respectively by spiking tests in the ranges of 20 mg/kg and 40 mg/kg using matrixes such as highlighter pen ink, board marker ink, chalk marker pen ink and painter marker ink.

• Journal of Science and Technology Studies
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• v.17 no.1
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• pp.5-39
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• 2017

In March 2016, the computer Go program, AlphaGo, defeated Sedol Lee, a Korean professional Go player of 9-dan rank. This victory by AlphaGo shows the rise in popularity of artificial intelligence (AI). Not only was this game a testament to machine performance, it was the type of game that extended the Turing test. When the interrogator cannot differentiate between human being and machine, the machine has passed the test. This article examines the interactions between AI and human beings and studies the social nature of intelligence through the AlphaGo case. Collins insists that knowledge or intelligence is social and embodied, and the interrogators in the Turing test can identify the difference between native members and non-members through their knowledge only. Applying this concept, AlphaGo, as subject A of this test, fulfilled its role of stirring up the classical "truth of human." Meanwhile, Lee as subject B, played to speak the truth by revealing his own qualities. Here, it is also important role that interrogators judge what it is. Many spectators, as interrogators, have intervened to confirm the border between human beings and machines by using their embodied and social knowledge.

• Analytical Science and Technology
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• v.12 no.5
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• pp.408-414
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• 1999

A selective and sensitive method for the derivatization of total homocysteine (Hcy) and the related compounds in plasma by gas chromatograph (GC)-electron capture detector (ECD) has been developed. To determine total homocysteine, cysteine (Cys), and methionine (Met) in human plasma using GC-ECD, analytes were reduced and converted into their N(O,S)-ethylearbonyl pentafluoropropyl (PFP) ester by derivatization with ethyl chloroformate and pentafluoropropyl alcohol (PFP-OH) in plasma. The best derivatizing agent N(O,S)-ethyl carbonyl PFP ester, was chosen by comparing the sensitivity of derivatized analysis in GC-ECD. The derivatized analytes in plasma were extracted by chloroform, and subsequently back-extracted with hexane and analyzed by GC-ECD. The calibration carves ($R^2$ > 0.990) were linear over the range $5-50{\mu}mol/L$ of Hcy and Met, $40-400{\mu}mol/L$ of Cys spiked in plasma. The detection limit observed by the established method was below $0.5{\mu}mol/L$. This method is highly sensitive and specific in the analysis of Hcy, Cys, and Met. Therefore, we suggest that this method is appropriate in the analysis of trace concentration of Hcy, Cys, and Met in biological fluids.

• Culinary science and hospitality research
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• v.15 no.4
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• pp.144-158
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• 2009

This study aims to provide the service quality which consumers want and basic data for improving their satisfaction by examining the difference among the quantity of cultural capital obtained from restaurant customers, the perception of service quality, and satisfaction. The results of the study are as follows. First, customer satisfaction is not much affected by how much cultural capital one has but by how much influence the cultural capital of parents or family has, or the institutionalized cultural capital. Second, the group that has more cultural capital objectives perceives tangibility, reliability and empathy lower than the one with less cultural capital in general while the group that has more cultural capital embodiments perceives tangibility and assurance higher than the one with less cultural capital; moreover, the group that has more cultural capital institutions perceives the service quality factor lower than the one with less cultural capital. Third, the higher the perception of the whole service quality is, the greater the satisfaction is. In this respect, it is required to offer the service to win customers' sympathy and trust as well as better external atmosphere. In addition, there should be continuous service training to foster employees' expertise and improve service quality, in order for restaurant customers to visit frequently with satisfaction and revisit intention.

• Journal of Science and Technology Studies
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• v.10 no.2
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• pp.107-141
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• 2010

Visualization techniques are transformed into reliable representations through socio-technological processes which include the agreement on the instrument and the embodiment of practices in relevant scientific communities. Visual representations thus produced are justified by realistic and epistemic virtues in science. This paper analyzes different visual images presented in the scientific papers of two research groups who argue different theories about the mechanism of face perception. These two scientific groups use the same fMRI technology; yet, different experimental paradigms and visual stimuli change their hypotheses into distinct testable theories, which in turn lead to different evidences to support their own theories. Visual evidences are intermediate representations which lie between fMRI brain images and scientific theories, and theoretical models obtain the scientific value based on the consistency in the chain of visual representations. This study shows that representations in science tend to be good representations within the context of scientific communities. It will provide a chance to think of the value and limit of the scientific knowledge

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.356-361
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• 2018

It is common to analyze volatile organic compound (VOC) or semi-VOC (SVOC) in a sample composed of a complex matrix consisting of multiple components such as bloods through a separation process. Adsorption is a physical phenomenon in which certain components accumulate on the surface of other phases. In order to overcome difficulties in the pretreatment process, an adsorption is frequently used. Solid phase microextraction (SPME) equipment with porous carbon carboxen (CAR) is an example of adsorption application. In this study, the adsorption of 4-octylphenol to carboxen was examined. To do so, the extraction efficiency for such solvents as dichloromethane ($CH_2Cl_2$, DCM), ethylacetate ($CH_3COOC_2H_5$, EA) and diethylether ($C_2H_5OC_2H_5$, $Et_2O$) was studied and also the derivatization reaction for 4-octylphenol with reagents of bistrimethylsilyltrifluoroacetamide (BSTFA), methylchloroformate (MCF) and pentafluorobenzylbromide (PFBBr) was compared. The combination of DCM and BSTFA showed good performance thus they were adopted for this study. Thermodynamic adsorption experiments showed that the adsorption process was endothermic and Freundlich isotherm equation was more suitable than Langmuir isotherm. It was also found that the adsorption followed a pseudo-$2^{nd}$ order kinetic model.

• Analytical Science and Technology
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• v.9 no.1
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• pp.52-61
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• 1996

Detectable levels of several free D-amino acids were found in some food. This was accomplished by using a column switching method. The determination of total amount of D- and L-amino acids was based on an achiral separation with a $C_{18}$ column. The level of D-amino acids to L-amino acids was determined by the column switching system including the postcolumn reaction detection of the amino acids derivatized with O-phthalaldehyde. The chiral separation of the postcolumn detection system was carried out with chiral crown ether column. This system was applied for the micro-determination of D-amino acids in food such as soy sauce, fermented soy bean and beans. It turned out that the sampling process is critical for the trace analysis of D-amino acids under this achiral / chiral coupled-column system. It was found that commercial soy sauce contained 42ppm, conventional soy sauce 102ppm, fermented soy bean 8.34mg per 1g and bean 2.87mg per 1g sample for phenylalanine. D-phenylalanine was found 0.67% in commercial soy sauce, 0.34% in conventional soy sauce, less than 1.81% in fermented soy bean, and Jess than 2.82% in bean.

• Journal of Food Hygiene and Safety
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• v.21 no.3
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• pp.153-158
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• 2006

The contamination levels of 3-MCPD(3-Monochloropropane-1,2-diol) and 1,3-DCP(1,3-Dichloro-2-Propanol) in soy sauce, sauces was monitored. 105 samples were collected from June 2005 to August 2005 in Gyeonggi-do. 3-MCPD and 1,3-DCP were analyzed by GCMSD. As results, the detection range of 3-MCPD concentration was between 0.02 mg/kg and 0.27 mg/kg in soy sauce. However any samples were not detected with 1,3-DCP. The contaminated rates of 3-MCPD in soy sauce was 17.1%. Soy sauce is the representative vegetable protein hydrolyzed food. The reliable analytical method f3r the toxic 3-MCPD and 1,3-DCP in Soy sauce has been studied. The derivatization studies of 3-MCPD and 1,3-DCP were performed mainly as Silylation with BSA(N,O-Bis(trimethylsilyl)-acetamide). The retention times of derivative, BSA-MCPD, BSA-DCP were 11.30 and 10.12 minutes.

• Journal of Applied Biological Chemistry
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• v.53 no.1
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• pp.25-30
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• 2010

This paper describes a simultaneous method for the determination of two aminoglycosides (neomycin and gentamicin) using solid phase extraction followed by liquid chromatograph-mass spectrometry. The extract was applied to an WCX and HLB solid phase extraction cartridge. The cartridges were washed with water and methanol, and analytes were eluted with TCA buffer-acetonitrile mixture. The aminoglycosides were separated by ion-pairing reversed phase mode prior to ESI-LC/MS. Under the conditions applied neomycin was almost separated from all the gentamicin compounds. No interfering peaks from endogenous compounds of matrix were noted at the elution position of the analytes. Recoveries of neomycin fortified at levels of 0.25, 0.5, 1.0 and 2.0 mg/kg seafood samples ranged from 92 to 115%. Recoveries of gentamycin fortified at levels of 0.05, 0.1, 0.2, 0.4 mg/kg seafood samples ranged from 99 to 116%. Method detection limits in four seafood sample matrices were between 0.002 and 0.033 mg/kg.