• Analytical Science and Technology
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• v.31 no.6
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• pp.240-246
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• 2018

The present study analyzed standard samples of three types of aluminum matrix certified reference materials (CRM) using GD-MS. Calibration curves were constructed for 13 elements (Mg, Si, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Sn, and Pb), with the slope representing the relative sensitivity factor (RSF). The x- and y-axes of the calibration curve represented ion beam ratio (IBR) and the authenticated value of the standard sample, respectively. In order to evaluate precision and linearity of the calibration curve, RSD and the coefficient of determination were calculated. Curve RSD for every element reflected high precision (within 10 %). For most elements, the coefficient of determination was ${\geq}0.99$, indicating excellent linearity. However, vanadium, nickel, and gallium curves exhibited relatively low linearity (0.90~0.95), likely due to their narrow concentration ranges. Standard RSF was calculated using the slope of the curve generated for three types of CRM. Despite vanadium, nickel, and gallium exhibiting low coefficients of determination, their standard RSF resembled that of the three types of CRM. Therefore, the RSF method may be used for element quantitation. Standard iron matrix samples were analyzed to verify the applicability of the aluminum matrix standard RSF, as well as to calculate the RSD-estimated error of the measured value relative to the actual standard value. Six elements (Al, Si, V, Cr, Mn, and Ni) exhibited an RSD of approximately 30 %, while the RSD of Cu was 77 %. In general, Cu isotopes are subject to interference: $^{63}Cu$ to $^{54}Fe^{2+}-^{36}Ar$ and $^{65}Cu$ to $^{56}Fe-Al^{3+}$ interference. Thus, the influence of these impurities may have contributed to the high RSD value observed for Cu. To reliably identify copper, the resolution should be set at ${\geq}8000$. However, high resolutions are inappropriate for analyzing trace elements, as it lowers ion permeability. In conclusion, quantitation of even relatively low amounts of six elements (Al, Si, V, Cr, Mn, and Ni) is possible using this method.

• Journal of Intelligence and Information Systems
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• v.25 no.3
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• pp.239-251
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• 2019

Statistical methods such as moving averages, Kalman filtering, exponential smoothing, regression analysis, and ARIMA (autoregressive integrated moving average) have been used for stock market predictions. However, these statistical methods have not produced superior performances. In recent years, machine learning techniques have been widely used in stock market predictions, including artificial neural network, SVM, and genetic algorithm. In particular, a case-based reasoning method, known as k-nearest neighbor is also widely used for stock price prediction. Case based reasoning retrieves several similar cases from previous cases when a new problem occurs, and combines the class labels of similar cases to create a classification for the new problem. However, case based reasoning has some problems. First, case based reasoning has a tendency to search for a fixed number of neighbors in the observation space and always selects the same number of neighbors rather than the best similar neighbors for the target case. So, case based reasoning may have to take into account more cases even when there are fewer cases applicable depending on the subject. Second, case based reasoning may select neighbors that are far away from the target case. Thus, case based reasoning does not guarantee an optimal pseudo-neighborhood for various target cases, and the predictability can be degraded due to a deviation from the desired similar neighbor. This paper examines how the size of learning data affects stock price predictability through k-nearest neighbor and compares the predictability of k-nearest neighbor with the random walk model according to the size of the learning data and the number of neighbors. In this study, Samsung electronics stock prices were predicted by dividing the learning dataset into two types. For the prediction of next day's closing price, we used four variables: opening value, daily high, daily low, and daily close. In the first experiment, data from January 1, 2000 to December 31, 2017 were used for the learning process. In the second experiment, data from January 1, 2015 to December 31, 2017 were used for the learning process. The test data is from January 1, 2018 to August 31, 2018 for both experiments. We compared the performance of k-NN with the random walk model using the two learning dataset. The mean absolute percentage error (MAPE) was 1.3497 for the random walk model and 1.3570 for the k-NN for the first experiment when the learning data was small. However, the mean absolute percentage error (MAPE) for the random walk model was 1.3497 and the k-NN was 1.2928 for the second experiment when the learning data was large. These results show that the prediction power when more learning data are used is higher than when less learning data are used. Also, this paper shows that k-NN generally produces a better predictive power than random walk model for larger learning datasets and does not when the learning dataset is relatively small. Future studies need to consider macroeconomic variables related to stock price forecasting including opening price, low price, high price, and closing price. Also, to produce better results, it is recommended that the k-nearest neighbor needs to find nearest neighbors using the second step filtering method considering fundamental economic variables as well as a sufficient amount of learning data.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.235-241
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• 2019

An analytical method was developed for the determination of an antibiotic fungicide, kasugamycin, in agricultural products (hulled rice, potato, soybean, mandarin and green pepper) using liquid chromatographytandem mass spectrometry (LC-MS/MS). Samples were extracted with methanol adjusted to pH 13 using 1 N sodium hydroxide, and purified with a HLB (hydrophilic lipophilic balance) cartridge. Linearity of a matrix-matched calibration curve using seven concentration levels, from 0.001 to 0.1 mg/kg, was excellent with a correlation coefficient ($R^2$) of more than 0.9998. The limits of detection (LOD) and quantification (LOQ) of instrument were 0.0005 and $0.001{\mu}g/mL$, respectively, and the LOQ of analytical method calculated as 0.01 mg/kg. The average recoveries at three spiking levels (LOQ, $LOQ{\times}10$, $LOQ{\times}50$, n=5) were in the range of 71.2~95.4% with relative standard deviation of less than 12.1%. The developed method was simple and all optimized results was satisfied with the criteria ranges requested in the Codex guidelines and Food Safety Evaluation Department guidelines. The present study could be served as a reference for the establishment of maximum residue limits (MRL) of kasugamycin and be used as basic data for safety management relative to kasugamycin residues in imported and domestic agricultural products.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.242-250
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• 2019

An analytical method was developed for the determination of fenquinotrione, a triketone herbicide, in agricultural products. Fenquinotrione was metabolized to KIH-3653-M-2 in plants. Analyte extraction was conducted using 2% formic acid in acetonitrile and cleaned up using a hydrophillic-lipophillic balance (HLB) cartridge. The limits of detection (LOD) and quantification (LOQ) were 0.004 and 0.01 mg/kg, respectively. Matrix-matched calibration curves were linear over the calibration ranges ($0.001{\sim}0.1{\mu}g/mL$) into a blank extract with $r^2>0.99$. The recovery results for fenquinotrione and KIH-3653-M-2 ranged between 81.1 to 116.2% and 78.0 to 110.0% at different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$) with relative standard deviation (RSD) less than 4.6%. All values were corresponded with the criteria ranges requested in both the Codex (CAC/GL 40-1993, 2003) and MFDS guidelines (2016). Therefore, the proposed method can be used as an official analytical method for determination of fenquinotrione in the Republic of Korea.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.115-123
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• 2019

An analytical method was developed for the determination of fenpropimorph, a morpholine fungicide, in hulled rice, potato, soybean, mandarin and green pepper using QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) sample preparation and LC-MS/MS (liquid chromatography-tandem mass spectrometry). The QuEChERS extraction was performed with acetonitrile followed by addition of anhydrous magnesium sulfate and sodium chloride. After centrifugation, d-SPE (dispersive solid phase extraction) cleanup was conducted using anhydrous magnesium sulfate, primary secondary amine sorbents and graphitized carbon black. The matrix-matched calibration curves were constructed using seven concentration levels, from 0.0025 to 0.25 mg/kg, and their correlation coefficient ($R^2$) of five agricultural products were higher than 0.9899. The limits of detection (LOD) and quantification (LOQ) were 0.001 and 0.0025 mg/kg, respectively, and the limits of quantification for the analytical method were 0.01 mg/kg. Average recoveries spiked at three levels (LOQ, $LOQ{\times}10$, $LOQ{\times}50$, n=5) and were in the range of 90.9~110.5% with associated relative standard deviation values less than 5.7%. As a result of the inter-laboratory validation, the average recoveries between the two laboratories were 88.6~101.4% and the coefficient of variation was also below 15%. All optimized results were satisfied the criteria ranges requested in the Codex guidelines and Food Safety Evaluation Department guidelines. This study could serve as a reference for safety management relative to fenpropimorph residues in imported and domestic agricultural products.

• Korean Journal of Environmental Agriculture
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• v.40 no.2
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• pp.108-117
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• 2021

BACKGROUND: Dichlobentiazox is a newly registered pesticide in Korea as a triazole fungicide and requires establishment of an official analysis method for the safety management. Therefore, the aim of this study was to determine the residual analysis method of dichlobentiazox for the five representative agricultural products. METHODS AND RESULTS: Three QuEChERS methods were applied to establish the extraction method, and the EN method was finally selected through the recovery test. In addition, various adsorbent agents were applied to establish the clean-up method. As a result, it was found that the recovery of the tested pesticide was reduced when using the d-SPE method with PSA and GCB, but C₁₈ showed an excellent recovery. Therefore this method was established as the final analysis method. For the analysis, LC-MS/MS was used with consideration of the selectivity and sensitivity of the target pesticide and was operated in MRM mode. The results of the recovery test using the established analysis method and inter laboratory validation showed a valid range of 70-120%, with standard deviation and coefficient of variation of less than 3.0% and 11.6%, respectively. CONCLUSION: Dichlobentiazox could be analyzed with a modified QuEChERS method, and the method determined would be widely available to ensure the safety of residual pesticides in Korea.

• Korean Journal of Poultry Science
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• v.48 no.3
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• pp.151-160
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• 2021

This study was conducted to determine the concentrations of particulate matter (PM) and NH3 emissions from different types of laying hens poultry houses during spring. The concentrations of PM and NH3 were measured three times (2-week intervals; March to May) in Floor-pen-, Aviary-, and Cage-type poultry houses. Overall, PM₁₀ and PM_2.5 concentrations were found to be low from 22:00 to 04:00. The PM₁₀ and PM_2.5 concentrations in Floor-pen and Cage houses were similar with no significant daily deviation. NH₃ concentrations measured over 24 h at the center and end of Floor-pen house were relatively constant. Irrespective of measurement location, NH₃ concentrations were the lowest in Floor-pen house. Moreover, NH₃ concentrations were higher at the end of Floor-pen and Aviary houses than that at the center; however, lower concentrations of NH₃ were detected at the end of Cage house. The concentrations of PM₁₀ and PM_2.5 around the poultry houses were 57.5 and 34.0 ㎍/m³, respectively, with the daily average PM₁₀ and PM_2.5 concentrations (4,730 and 447.7 ㎍/m³, respective) being the highest in Aviary house. The concentrations of NH₃ at the center and end of Cage house were the highest at 12.0 and 9.31 ppm, respectively. Furthermore, in Cage house, the emission factor of NH₃ was the lowest, whereas there was no significant difference on that of NH₃. In conclusion, among the three types of poultry houses assessed, PM (PM₁₀, PM_2.5) concentrations were higher in Aviary house, whereas NH3 concentrations were higher in Cage house.

• Journal of the Korean Electrochemical Society
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• v.24 no.3
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• pp.65-75
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• 2021

Coin cell is a basic testing platform for battery research, discovering new materials and concepts, and contributing to fundamental research on next-generation batteries. Li metal batteries (LMBs) are promising since a high energy density (~500 Wh kg^-1) is deliverable far beyond Li-ion. However, Li dendrite-triggered volume fluctuation and high surface cause severe deterioration of performance. Given that such drawbacks are strongly dependent on the cell parameters and structure, such as the amount of electrolyte, Li thickness, and internal pressure, reliable Li metal coin cell testing is challenging. For the LMB-specialized coin cell testing platform, this study suggests the optimal coin cell structure that secures performance and reproducibility of LMBs under stringent conditions, such as lean electrolyte, high mass loading of NMC cathode, and thinner Li use. By controlling the cathode/anode (C/A) area ratio closer to 1.0, the inactive space was minimized, mitigating the cell degradation. The quantification and imaging of inner cell pressure elucidated that the uniformity of the pressure is a crucial matter to improving performance reliability. The LMB coin cells exhibit better cycling retention and reproducibility under higher (0.6 MPa → 2.13 MPa) and uniform (standard deviation: 0.43 → 0.16) stack pressure through the changes in internal parts and introducing a flexible polymer (PDMS) film.

• (The)Study of the Eastern Classic
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• no.72
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• pp.299-327
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• 2018

The objective of this study is to examine the regional distribution of Ssireum(Traditional Wrestling) of South and North Korea in the Japanese colonial era. The conclusions of this study are as follows. First, the "Joseon ui hyangto orak(Folk play in Joseon)" showed the record of performing 272 times of Ssireum in 226 regions of the whole nation. Second, the Ssireum of South Korea could be divided into five regions. Seoul/Gyeonggi-do performed Ssireum the most in Dano, Baekjung, and Chuseok while Chungcheong-do performed Ssireum in Baekjung and Chuseok. Jeolla-do and Gyeongsang-do performed Ssireum in Chuseok while Gangwon-do performed Ssireum in Dano and Chuseok. Third, the Ssireum of North Korea could be divided into three regions. All the Hwanghae-do, Pyeongan-do, and Hamgyeong-do performed Ssireum the most in Dano. Fourth, as the period when Ssireum was held the most in the whole nation, Dano, Baekjung, and Chuseok could be pointed out. Ssireum has the characteristics of large-scale play between village communities or regions, instead of individual game. Thus, the Ssireum that was played as a sport event under certain rules for a long time was settled down as a folk play of regional festivals such as Dano, Baekjung, and Chuseok. Fifth, as a folk play and a representative play of seasonal customs, Ssireum was distributed in the whole nation and handed down till today under the regional deviation of South and North Korea. Sixth, the unidentified regions of South Korea that did not perform Ssireum were six places including five dos such as Gapyeong Gyeonggi-do, Boseong Jeollanam-do, Jeju-do, Gunwi and Cheongsong Gyeongsanbuk-do, and Inje Gangwon-do. The regions of North Korea were six places including three dos such as Pyeongyang, Yangdeok, Gangdong, and Gaecheon of Pyeongannam-do, Bakcheon Pyeonganbuk-do, and Dancheon Hamgyeongnam-do. Total 12 places in eight regions were included. Seventh, the number of total items of play names presented in the "Joseon ui hyangto orak(Folk play in Joseon)" was about 6,400 types. Out of them, about 1,300 types were the items including how to play while about 5,100 types were the items presenting the play names only without explanations. Especially, in case of Ssireum, the periods of the lunar calendar were only specified in each region. Unfortunately, it was not possible to check the contents about the actual performance methods and types of Ssireum as they were omitted.

• (The)Study of the Eastern Classic
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• no.43
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• pp.7-31
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• 2011

Danjong had suffered the worst misfortune in the history of Lee Dynasty. His throne was usurped by Sejo, his uncle and he was banished to Youngwol where he ended his life for good. Youngwol remembers the last moment of this tragic person clearly through the various traditional stories passed down from the past. In this study, the works assumed to be formed in the contemporary times among Danjong-related stories were targeted. Time of story creation is not known but it could be assumed that the time when heroine of the story was lived may be coincided with the time of traditional story creation, in this story created in a form of experience story. If any objects or elements that may lead to time of traditional story are contained in the story, we may be able to identify the time of traditional story. All of , and were created in the contemporary times. However, these traditional stories are not new at all. If any personal experience story is added on the existing transmitted traditional story, deviation of traditional story near to recreation is taken place. Traditional Danjong story created like this in the contemporary times have some characteristics. First, transmission power of maintaining Danjong story up to the present times was expanded from a nature of misfortune and holiness to general eccentricity. Ability of deity derived from Danjong's grief and grudge is weakened as time goes by and this story is substituted by an amazing things that can be experienced by anybody. Second, at present, Danjong story is transformed to a form of folktale. Danjong story has developed into a myth through deification from a personal legend. This myth is transformed into a folktale everybody can experience in the contemporary times. Third, this story has been recreated in a form of experience story, not a modification. It is said that as the personal experience story is combined with existing traditional stories, a new work of traditional story is created. It could be observed that through contemporary Danjong story, traditional story of historical person could be created in the contemporary times as well and additionally, a process that personal experience story is positioned as a traditional story could be observed. Now is the time to pay attention to various traditional stories being created in the contemporary times like experience stories.