• Communications of Mathematical Education
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• v.18 no.1 s.18
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• pp.123-136
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• 2004

수학이라는 학문 자체가 몇 가지 정의와 공리로부터 논리 법칙을 이용하여 명제나 정의를 유도하고 확장하는 공리적인 성격을 지니고 있기 때문에 그러한 논리 전개의 진위 여부를 판별해주는 증명은 수학에서 아주 중요하다. 특히 중학교 2학년 학생들은 정의와 성질을 이용한 증명을 다루는데 정의와 성질의 역할을 제대로 구분하지 못할 경우 증명 자체가 어려워진다. 학생들을 가르치다 보면 정의와 성질을 구분하지 못하고 증명과정에서 정의와 성질이 어떤 역할을 하는지 제대로 알지 못하는 경우가 종종 있다. 본 연구에서는 정의와 성질의 구분 실태를 조사하고, 정의와 성질의 구분에 어려움이 있는 학생들을 대상으로 증명과정에서 정의와 성질의 역할에 대하여 학생들이 겪는 어려움과 처치과정의 사례 연구를 통하여 분석함으로써 증명 교육의 바람직한 방안을 모색하고자 한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.1
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• pp.81-88
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• 2007

In on-line transaction, the transparency is the key factor for the taxation and customer's rights. Using the cash register concept of the off-line transaction, we studied on-line transaction register model for the e-commerce transparency. Although on-line transaction register may be used under the related e-commerce laws, in this paper, we only considered the mechanism of the register. The register issues the digital receipt, and then the receipt can be verified the validation by the models developed in this paper.

• Journal of Food Hygiene and Safety
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• v.23 no.3
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• pp.212-217
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• 2008

This survey was conducted to monitor the adulteration of sesame oil circulated in Gwangju, 2007. A total of 60 samples was tested by analysis of fatty acid composition. Of these samples, 22 were from large-scale manufacturer, 25 were from small-scale manufacturer and 13 from Bangagan. First of all, in goods manufactured by large-scale company, there are no sesame oils where linolenic acid($C_{18:3}$) exceed regulatory guidance(0.5%). 5 samples from small-scale manufacturer contained linolenic acid from 0.90% to 8.38%, which means that they have other cooking oil, such as com oil, soybean oil and rape seed oil. Among Bangagan goods, only one sample have 1.20% of linolenic acid. On the other hand erucic acid($C_{22:1}$) was not detected in 60 samples at all, which means that they were not adulterated with rape seed oil. And among 6 samples of exceeding 0.5% of linolenic acid and 12 samples from Bangagan, 13 of them had benzo(a)pyrene from $0.2{\mu}g/kg\;to\;0.7{\mu}g/kg$ and the other 5 samples did not.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.691-699
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• 2018

Astronomical positioning has been carried out from the past by using Sextant. The St. Hilaire method was mainly used by Nautical Almanac and Sight Reduction Tables For Marine Navigation. In modern times, it has been able to use the LOP(Line of Position) method smoothly by combining with IT technology. However, in comparison with the past method, the LOP method always shows two positions, True Position and False Position, which must be distinguished by the navigator. Therefore, in this paper, we proposed a method of using the azimuth to remove the false position generated by the LOP method. In particular, the theoretical considerations using azimuth are presented in various ways, and the validity of the theoretical considerations is confirmed. Simulations are presented to confirm that the theoretical basis of the thesis is valid.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.317-324
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• 2012

In order to determine an authenticity of food ingredient, we used DNA barcode method by universal primers. For identification of animal food ingredients, LCO1490/HCO2198 and VF2/FISH R2 designed for amplifying cytochrome c oxidase subunit1 (CO1) region and L14724/H15915 for cytochrome b (cyt b) region on mitochondrial DNA were used. Livestock (cow, pig, goat, sheep, a horse and deer) was amplified by LCO1490/HCO 2198, VF2/FISH R2 and L14724/H15915 primers. Poultry (chicken, duck, turkey and ostrich) was amplified by LCO1490/HCO 2198 and VF2/FISH R2 primers. But, Fishes (walleye pollack, herring, codfish, blue codfish, trout, tuna and rockfish) were only amplified by VF2/FISH R2 primers. For plant food ingredients, 3 types of primers (trnH/psbA, rpoB 1F/4R and rbcL 1F/724R) have been used an intergenic spacer, a RNA polymerase beta subunit and a ribulose bisphosphate carboxylase region on plastid, respectively. Garlic, onion, radish, green tea and spinach were amplified by trnH/psbA, rpoB 1F/4R and rbcL 1F/724R. The PCR product sizes were same by rpoB 1F/4R and rbcL 1F/724R but, the PCR product size using trnH/psbA primer was different with others for plants each. We established PCR condition and universal primer selection for 17 item's raw materials for foods and determine base sequences aim to PCR products in this study. This study can apply to determine an authenticity of foods through making an comparison between databases and base sequences in gene bank. Therefore, DNA barcode method using universal primers can be a useful for species identification techniques not only raw materials but also processed foods that are difficult to analyze by chemical analysis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.7
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• pp.874-880
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• 2006

The volatile compounds of Zingiber officinale Roscoe were extracted by simultaneous steam distillation and extraction (SDE) method and identified with gas chromatigraphy/mass spectrometer (GC/MS) analysis. Enantiomeric compositions of chiral compounds were determined by multidimensional gas chromatography/mass spectrometer (MDGC/MS). A total of 57 compounds were indentified and quantified, including zingiberene, ${\beta}-sesquiphellandrene$, ${\beta}-bisabolene$, $(E,E)-{\alpha}-farnesene$ and ${\alpha}-curcumene$. Among them, zingiberene (38.41%) was founds as the predominantly abundant component. ${\alpha}-Pinene$ and nerolidol in dried ginger were detected by high enantiomeric purity (>96%) for (S)-form, and ${\beta}-pinene$ was detected only (R)-form. The enantiomeric composition of ${\alpha}-terpineol$ revealed 72.0% for (R)-form, and linalool and 4-terpineol showed mixtures of both enantiomers. (S)-Enantiomer was the major enantiomer of limonene having enatiomeric excess of 17.2%. Hence the enantiomeric composition of these compounds can be used as parameter for authenticty control of Zingiber officinale.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.609-614
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• 2009

Sesame oil was sometimes replaced by mixed oil due to high price in Korean market. To find out authentic sesame oil, electronic nose (E-nose) based on mass spectrometer system was used. Sesame oil was blended with perilla oil at the ratio of 97:3, 94:6, 91:9, 88:12 and 85:15, respectively. Intensities of each fragment from sesame oil by E-nose based on MS were completely different from those of perilla oil. The obtained data was used for discriminant function analysis. For quantitative analysis, the partial least square algorithm was used. The added concentration of perilla oil to sesame oil was correlated with discriminant function first score (DF1) and second score (DF2). From this relationship it could be found out how much perilla oil added. DFA plot indicated a significant separation of pure sesame oil and pure perilla oil. The different geographical origin of sesame oil was used for blending with perilla oil were closed to that of sesame oil. Korean sesame oil mixture and Indian sesame oil one were well separated. And the correlation between mixing ratios and DF1 values was found at the ratio of 97:3, 91:9, and 85:15 (SE vs PE oil), respectively. But the added concentration of perilla oil to sesame oil was correlated with discriminant function first score (DF1). E-nose based on MS system could be used as an efficient method for purity of oil quality.

• Food Engineering Progress
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• v.13 no.4
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• pp.275-281
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• 2009

Sesame oils are partially mixed with other vegetable oils due to high price in a Korean market. To find out authentic sesame oil, a mass spectrometer-based electronic nose (MS-based E-nose) was used. Sesame oil (Se) was blended with soybean oil (So) or corn oil (Co) at the ratio (Se:So, Se:Co) of 97:3, 94:6, 91:9, 88:12 and 85:15, respectively. Intensities of each fragment from sesame oil by MS-based E-nose were completely different from those of soybean oil or corn oil. The obtained results were used for discriminant function analysis (DFA). Volatile organic components (VOC) of soybean oil or corn oil were similar to those of fresh air and DFA plot indicated a significant separation of pure sesame oil and pure other oil. The group of the mixed oil was seperated with that of sesame oil in DFA plot and the added amount of soybean oil to sesame oil was correlated with discriminant function first score (DF1). MS based E-nose system could be used as an efficient method to investigate the purity of sesame oil.

• The Journal of the Korea Contents Association
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• v.22 no.4
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• pp.337-351
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• 2022

With the full spread and rapid development of social media, the trend of decentralization of social media information propagation is becoming clearer day by day, and the segmentation of time by audiences using social media information is clearly progressing. Therefore, this study aims to study the influence relationship between social media attitudes toward fake news, social capital, risk perception, and discriminant intentions based on existing studies. Accordingly, the research model presented related research questions and organized a questionnaire to collect a total of 500 valid surveys. The SPSS 26.0 program and the AMOS 24.0 program were used to analyze the data. The research results are as follows. First, the more positive the user's attitude towards the fake news identification intention of social media, the more they want to use various methods or tools to identify the authenticity of online information. Second, the more positive the user's attitude towards social media fake news, the more aware of the potential threats social media fake news poses to their own physical, psychological, financial and so on. At the same time, by raising one's own awareness of the dangers, counterintelligence intentions against fake news on social media will also increase. Third, the richer the social capital the user has, the stronger the information literacy, and therefore the stronger the identification intention of social media fake news. Fourth, the higher the value of social capital Chinese users have, the greater the damage they have suffered from fake news, and the higher the risk awareness of fake news to protect their interests. Fifth, it means that Chinese users recognized information suspected of social media and took corresponding measures.

• Journal of Food Hygiene and Safety
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• v.27 no.1
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• pp.68-73
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• 2012

In this study, a method was developed using molecular biological technique to distinguish an authenticity of meats for processed meat products. The genes for distinction of species about meats targeted at 12S or 16S genes in mitochondrial DNA and the species-specific primers were designed by that PCR products' size was around 200bp for applying to processed products. The target materials were 10 species of livestock products and it checked whether expected PCR products were created or not by electrophoresis after PCR using species-specific primers. The results of PCR for beef, pork, goat meat, mutton, venison, and horse meat were 131, 138, 168, 144, 191, and 142 bp each. The expected PCR products were confirmed at 281, 186, 174, and 238 bp for chicken, duck, turkeymeat, and ostrich. Also, non-specific PCR products were not detected in similar species by species-specific primers. The method using primers developed in this study confirm to be applicable for composite seasoning including beefs and processed meat products including pork and chicken. Therefore, this method may apply to distinguish an authenticity of meats for various processed products.