• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1196-1206
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• 2021

Purpose To construct a standard dataset of contrast-enhanced CT images of liver tumors to test the performance and safety of artificial intelligence (AI)-based algorithms for clinical decision support systems (CDSSs). Materials and Methods A consensus group of medical experts in gastrointestinal radiology from four national tertiary institutions discussed the conditions to be included in a standard dataset. Seventy-five cases of hepatocellular carcinoma, 75 cases of metastasis, and 30-50 cases of benign lesions were retrieved from each institution, and the final dataset consisted of 300 cases of hepatocellular carcinoma, 300 cases of metastasis, and 183 cases of benign lesions. Only pathologically confirmed cases of hepatocellular carcinomas and metastases were enrolled. The medical experts retrieved the medical records of the patients and manually labeled the CT images. The CT images were saved as Digital Imaging and Communications in Medicine (DICOM) files. Results The medical experts in gastrointestinal radiology constructed the standard dataset of contrast-enhanced CT images for 783 cases of liver tumors. The performance and safety of the AI algorithm can be evaluated by calculating the sensitivity and specificity for detecting and characterizing the lesions. Conclusion The constructed standard dataset can be utilized for evaluating the machine-learning-based AI algorithm for CDSS.

• Journal of Korean Dental Hygiene Science
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• v.6 no.2
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• pp.151-160
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• 2023

Background: This study analyzed the differences in practice satisfaction, major, and willingness to work abroad among dental hygiene department students at K University in Gangwon-do based on their participation in international practicums. Methods: A survey was conducted on a total of 215 students through convenience sampling of dental hygiene students, and the final 214 responses were analyzed. General characteristics were examined. Major satisfaction and grades were measured on a 5-point Likert scale. And satisfaction with practice, intention to participate in international practicums, and employment were investigated by papers. Descriptive statistical analysis was performed on general characteristics using SPSS software (version 26.0). Due to the convenience sample, nonparametric analysis was used to determine satisfaction with practice and major according to general characteristics using the Mann-whitney U and Kruskal-wallis test. An independent samples t-test was conducted to determine the difference between practice satisfaction and major satisfaction depending on participation in international practicums, and Fisher's exact test was conducted to determine practice satisfaction, willingness to participate in overseas internships, and employment. Results: Concerning future participation in international clinical practicums, 66.7% of students who had previously participated in overseas training expressed willingness to engage again. 40.9% of those who had not participated showed no intention of participating, and there was a significant difference (p<0.05). Additionally, 76.2% of the participants expressed interest in overseas employment, with this difference also being statistically significant (p<0.05). Conclusion: It was confirmed that students' satisfaction with practice and major increased through participation in international practicums, and that they had a positive intention to work abroad and participate in overseas internship programs in the future.

• Journal of Food Hygiene and Safety
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• v.39 no.1
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• pp.16-25
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• 2024

This study investigated the prevalence of Campylobacter spp. In poultry meat and its association with foodborne illnesses in Gwangju, South Korea. It was found that out of the 307 samples of poultry meat examined, 111 (36.2%) were infected with Campylobacter spp. Among the isolated strains, 102 were identified as Campylobacter jejuni and 14 as Campylobacter coli. The detection rate of Campylobacter spp. was higher in duck meat (63.1%) than in chicken meat (26.0%). In 5 samples (1 chicken, 4 duck), both Campylobacter jejuni and Campylobacter coli were found together. The antimicrobial resistance test showed that 99 strains were resistant to more than one antimicrobial. The most common antimicrobial resistance was seen against ciprofloxacin (84.5%), followed by nalidixic acid (82.8%), tetracycline (44.0%), and gentamicin (2.6%). The isolated Campylobacter spp. were serotyped and the results showed the presence of HS2 (20 strains), HS15 (11 strains), HS19 (9 strains), and HS8 (8 strains). Considering the findings, it is recommended to maintain hygienic practices during the cooking process and to take necessary precautions to prevent the spread of pathogenic bacteria.

• Journal of the Korean Society of Radiology
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• v.85 no.3
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• pp.618-630
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• 2024

Purpose To compare the efficacy and safety of radiofrequency ablation (RFA) and ethanol ablation (EA) followed by RFA in treating mixed cystic and solid thyroid nodules. Materials and Methods We included 243 nodules from 243 patients who underwent RFA for mixed cystic and solid benign nodules. The nodules were divided into two groups (RFA alone and EA + RFA). We evaluated volume reduction rate (VRR), therapeutic success rate, improvement in symptomatic and cosmetic issues, complications, and adverse effects. Results The RFA group included 204 patients, and the EA + RFA group included 39 patients. The long-term success rates in the RFA only and EA + RFA groups were 90.2% and 97.4%, respectively. The mean VRR at the last follow-up in the RFA and EA + RFA groups were 81.6% and 87.2%, respectively. Therapeutic results were similar in both groups at the last followup. Cosmetic and symptomatic problems markedly improved in both groups. No major complications were observed. Conclusion Both RFA alone and EA + RA are safe and effective methods for treating mixed cystic and solid thyroid nodules, although EA + RFA is slightly more effective.

• Journal of the Korean Society of Radiology
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• v.84 no.1
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• pp.185-196
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• 2023

Purpose This study aimed to investigate radiomics analysis of ultrasonographic images to develop a potential biomarker for predicting lymph node metastasis in papillary thyroid carcinoma (PTC) patients. Materials and Methods This study included 431 PTC patients from August 2013 to May 2014 and classified them into the training and validation sets. A total of 730 radiomics features, including texture matrices of gray-level co-occurrence matrix and gray-level run-length matrix and single-level discrete two-dimensional wavelet transform and other functions, were obtained. The least absolute shrinkage and selection operator method was used for selecting the most predictive features in the training data set. Results Lymph node metastasis was associated with the radiomics score (p < 0.001). It was also associated with other clinical variables such as young age (p = 0.007) and large tumor size (p = 0.007). The area under the receiver operating characteristic curve was 0.687 (95% confidence interval: 0.616-0.759) for the training set and 0.650 (95% confidence interval: 0.575-0.726) for the validation set. Conclusion This study showed the potential of ultrasonography-based radiomics to predict cervical lymph node metastasis in patients with PTC; thus, ultrasonography-based radiomics can act as a biomarker for PTC.

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.482-496
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• 2023

Many changes in the scale and structure of the Korean rice cropping system have been made over the past few decades. Still, insufficient research has been conducted on the sustainability of this system. This study analyzed changes in the Korean rice cropping system's sustainability from a system ecology perspective using an emergy approach. For this purpose, an emergy table was created for the Korean rice cropping system in 2011, 2016, and 202, and an emergy-based indicator analysis was performed. The emergy analysis showed that the total emergy input to the rice cropping system decreased from 10,744E+18 sej year^-1 to 8,342E+18 sej year^-1 due to decreases in paddy field areas from 2011 to 2021, and the proportion of renewable resources decreased by 1.4%. The emergy input per area (ha) was found to have decreased from 13.13E+15 sej ha^-1 year^-1 in 2011 to 11.89E+15 sej ha^-1 year^-1 in 2021, and the leading cause was a decrease in nitrogen fertilizer usage and working hours. The amount of emergy used to grow 1 g of rice stayed the same between 2016 and 2021 (specific emergy: 13.3E+09 sej g^-1), but the sustainability of the rice cropping system (emergy sustainability index, ESI) continued to decrease (2011: 0.107, 2016: 0.088, and 2021: 0.086). This study provides quantitative information on the emergy input structure and characteristics of Korean rice cropping systems. The results of this study can be used as a valuable reference in establishing measures to improve the ecological sustainability of the Korean rice cropping system.

• Journal of Intelligence and Information Systems
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• v.23 no.2
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• pp.123-138
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• 2017

Since the stock market is driven by the expectation of traders, studies have been conducted to predict stock price movements through analysis of various sources of text data. In order to predict stock price movements, research has been conducted not only on the relationship between text data and fluctuations in stock prices, but also on the trading stocks based on news articles and social media responses. Studies that predict the movements of stock prices have also applied classification algorithms with constructing term-document matrix in the same way as other text mining approaches. Because the document contains a lot of words, it is better to select words that contribute more for building a term-document matrix. Based on the frequency of words, words that show too little frequency or importance are removed. It also selects words according to their contribution by measuring the degree to which a word contributes to correctly classifying a document. The basic idea of constructing a term-document matrix was to collect all the documents to be analyzed and to select and use the words that have an influence on the classification. In this study, we analyze the documents for each individual item and select the words that are irrelevant for all categories as neutral words. We extract the words around the selected neutral word and use it to generate the term-document matrix. The neutral word itself starts with the idea that the stock movement is less related to the existence of the neutral words, and that the surrounding words of the neutral word are more likely to affect the stock price movements. And apply it to the algorithm that classifies the stock price fluctuations with the generated term-document matrix. In this study, we firstly removed stop words and selected neutral words for each stock. And we used a method to exclude words that are included in news articles for other stocks among the selected words. Through the online news portal, we collected four months of news articles on the top 10 market cap stocks. We split the news articles into 3 month news data as training data and apply the remaining one month news articles to the model to predict the stock price movements of the next day. We used SVM, Boosting and Random Forest for building models and predicting the movements of stock prices. The stock market opened for four months (2016/02/01 ~ 2016/05/31) for a total of 80 days, using the initial 60 days as a training set and the remaining 20 days as a test set. The proposed word - based algorithm in this study showed better classification performance than the word selection method based on sparsity. This study predicted stock price volatility by collecting and analyzing news articles of the top 10 stocks in market cap. We used the term - document matrix based classification model to estimate the stock price fluctuations and compared the performance of the existing sparse - based word extraction method and the suggested method of removing words from the term - document matrix. The suggested method differs from the word extraction method in that it uses not only the news articles for the corresponding stock but also other news items to determine the words to extract. In other words, it removed not only the words that appeared in all the increase and decrease but also the words that appeared common in the news for other stocks. When the prediction accuracy was compared, the suggested method showed higher accuracy. The limitation of this study is that the stock price prediction was set up to classify the rise and fall, and the experiment was conducted only for the top ten stocks. The 10 stocks used in the experiment do not represent the entire stock market. In addition, it is difficult to show the investment performance because stock price fluctuation and profit rate may be different. Therefore, it is necessary to study the research using more stocks and the yield prediction through trading simulation.

• Tuberculosis and Respiratory Diseases
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• v.43 no.4
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• pp.558-570
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• 1996

Background : The detection of Collapsible airways has important therapeutic implications in chronic airway disease and bronchial asthma. The distinction of a purely collapsible airways disease from that of asthma is important because the treatment of the dormer may include the use of pursed lip breathing or nasal positive pressure ventilation whereas in the latter, pharmacologic approaches are used. One form of irreversible airflow limitation is collapsible airways, which has been shown to be a Component of asthma or to emphysema, it can be assessed by the volume difference between what exits the lung as determined by a spirometer and the volume compressed as measured by the plethysmography. Method : To investigate whether volume difference between slow and forced vital Capacity(SVC-FVC) by spirometry may be used as a surrogate index of airway collapse, we examined pulmonary function parameters before and after bronchodilator agent inhalation by spirometry and body plethysmography in 20 cases of patients with evidence of airflow limitation(chronic obstructive pulmonary disease 12 cases, stable bronchial asthma 7 cases, combined chronic obstructive pulmonary disease with asthma 1 case) and 20 cases of normal subjects without evidence of airflow limitation referred to the Pusan National University Hospital pulmonary function laboratory from January 1995 to July 1995 prospectively. Results : 1) Average and standard deviation of age, height, weight of patients with airflow limitation was $58.3{\pm}7.24$(yr), $166{\pm}8.0$(cm), $59.0{\pm}9.9$(kg) and those of normal subjects was $56.3{\pm}12.47$(yr), $165.9{\pm}6.9$(cm), $64.4{\pm}10.4$(kg), respectively. The differences of physical characteristics of both group were not significant statistically and male to female ratio was 14:6 in both groups. 2) The difference between slow vital capacity and forced vital capacity was $395{\pm}317ml$ in patients group and $154{\pm}176ml$ in normal group and there was statistically significance between two groups(p<0.05). Sensitivity and specificity were most higher when the cut-off value was 208ml. 3) After bronchodilator inhalation, reversible airway obstructions were shown in 16 cases of patients group, 7 cases of control group(p<0.05) by spirometry or body plethysmography d the differences of slow vital capacity and forced vital capacity in bronchodilator response group and nonresponse group were $300.4{\pm}306ml$, $144.7{\pm}180ml$ and this difference was statistically significant. 4) The difference between slow vital capacity and forced vital capacity before bronchodilator inhalation was correlated with airway resistance before bronchodilator(r=0.307 p=0.05), and the difference between slow vital capacity and forced vital capacity after bronchodilator was correlated with difference between slow vital capacity and forced vital capacity(r=0.559 p=0.0002), thoracic gas volume(r=0.488 p=0.002) before bronchodilator and airway resistance(r=0.583 p=0.0001), thoracic gas volume(r=0.375 p=0.0170) after bronchodilator, respectively. 5) The difference between slow vital capacity and forced vital capacity in smokers and nonsmokers was $257.5{\pm}303ml$, $277.5{\pm}276ml$, respectively and this difference did not reach statistical significance(p>0.05). Conclusion : The difference between slow vital capacity and forced vital capacity by spirometry may be useful for the detection of collapsible airway and may help decision making of therapeutic plans.

• Journal of Life Science
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• v.12 no.6
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• pp.700-707
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• 2002

To study the characteristics of organic and nutrient removal by Bacillus species at high COD concentration of influent, three lab-scale batch reactors(R1, R2, R3), each of which has different substrate composition, were operated. More than 95% of $NH_4^+$-N and $COD_{cr}$, concentrations were removed under an aerobic condition, and their removal efficiencies were found to be 22.6 and 90.5%(R1), 23.9 and 65.8%(R2), 30.2 and 86.4%(R3), respectively. The removal efficiency of $NH_4^+$-N was high when an enough amount of $NO_3^{-}$-N was supplied, and that of $COD_{cr}$. was low when a high concentration of initial $NO_2^{-}$-N was added. The amount of carbon utilized in denitrification was a little. In all reactors,$NO_3^{-}$-N was removed under an anoxic condition, but in the R3 reactor, 10% of $NO_3^{-}$-N could be removed even undo, an aerobic condition. The removal efficiencies of TN and TP were 41.8 and 49.5%(R1), 40.1 and 35.8%(R2), 47.0 and 57.6%(R3), respectively. Alkalinities destructed under an aerobic condition for each reactor were 4.96, 5.41 and 3.93 mg/L (as $CaCO_3$) per each gram of $NH_4^+$-N oxidized, respectively, while 3.06, 3.17 and 2.60 mg/L (as $CaCO_3$) of alkalinities were produced for each gram of ,$NO_3^{-}$-N reduced to $N_2$. The SOUR were found to be 38.5, 52.7 and 42.0 mg $O_2$/g MLSS/hr, which indicated that Bacillus sp. had a higher cell activity than activated sludge. The OLR and sludge production were estimated to be 0.69 and 0.28(Rl), 0.77 and 0.20(R2), 0.61 kg COD/$m^3$/day and 0.25 kg MLSS/kg COD(R3), respectively. From the N-balance, the highest percentage(40.9%) of nitrogen lost to $N_2$ was obtained in the R3 reactor. From all the results, the possibility of aerobic denitrification Bacillus sp. has been shown and the B3 process seemed to have two advantages: a little amount of carbon was required in denitrification and not much amount of alkalinity was destructed under an aerobic condition.

• Korean Journal of Psychosomatic Medicine
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• v.7 no.1
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• pp.87-102
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• 1999

Objectives : The purposes of this study were to estimate the prevalence rate of eating disorders in Korean males and to clarify their characteristics in sociodemograhic data, the eating traits, and general psychopathology through the comparison with those of female high scored group on the Korean version of Eating Attitudes Test-26(KEAT-26). Methods : Using a multi-stage questionnaire sampling method including area sampling, proportionated stratified sampling, and quota sampling, we surveyed a total of 4,400 Korean adults over 18 in a nationwide area(9 kus, 10 middle or small cities, and 17 kuns), obtaining usable responses on 3,896. Of the 3,062 subjects(1249 males and 1813 females) who were available for analysis, we ascertained 52 males and 208 females who had high score($\geq$ cutoff point 21) on the KEAT-26. Results : 1) The proportion of this high score group was 1.7% in male and 6.8% in female with a sex ratio(male versus female) of 1 : 4. 2) The mean age was higher in the male group than in the female group, although it was not statistically significant(p=0.0514). Mean Body Mass Index(BMI) of the male group was significantly higher than that of female group, and the number of male subjects with below 20 of BMI was also significantly lower than in the female group. 3) There were no significant difference in past history of physical illness between two groups. However, frequency of smoking and alcohol use, and mean amount of alcohol consumption per month were significantly higher in the male group than in the female group. There were no significant differences between the two groups on various socio-demographic correlates such as economic status, total duration of education, number of family, marital status, religious status, and area of residence, but the exception of being occupational status. 4) The 'Eating Habits Scale' score and score of 'preference for vegetables and fish, and dislike for sweet-tasting food' of the male group were significantly lower than those of the female group. Although there was no significant difference between the two groups in total scores of the KEAT-26, the mean score on 'pursuit of thinness' subscale was higher in the female group than in the male group, while scores of 'food preoccupation' and 'self-control' subscales were higher in the male group than in the female group. 5) Scores on 'psychoticism' was significantly higher in the male group than in the female group, although there were no significant differences between the two groups on 'locus of control for weight', 'depression' and 'hypochondriasis'. Conclusion : These results support a possibility of a high prevalence of eating disorders in Korean males. These results suggest that eating related characteristics of high scorer on the EAT are different by sex in spite of the same high score on the EAT, and also suggest that male patients with eating disorders have more serious personality pathology than female patients with eating disorders.