• Clean Technology
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• v.26 no.4
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• pp.270-278
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• 2020

Palladium (Pd) has been widely used in various industrial applications such as jewelry, catalyst, and dental materials despite its limited resources. It has been gaining attention to recover Pd with high purity from the spent materials. This study investigated the optimum conditions for the leaching and recovery of metallic Pd. The leaching parameters are HCl concentration, temperature, time, concentration of oxidants, and pulp density. 97.2% of Pd leaching efficiency was obtained in 3 M HCl with 3 vol% oxidants at 80℃ for 60 min. The ratio of hydrogen peroxide to sodium hypochlorite played a critical role in the leaching efficiency due to the supply of Cl- ions in the leachate. Moreover, the complete recovery of Pd in the leachate was achieved at 80℃ with 0.3 formic acid/leachate after adjusting the pH value of 7. This situation was ascribed to the decomposition of formic acid into hydrogen gas and carbon dioxide at 80℃. ICP-AES and XRD characterized the recovered Pd powder, and the purity of the recovered powder was found to be 99.6%. Consequently, the recovered Pd powder with high purity could be used in circuits, catalyst precursors, and surgical instruments.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.491-498
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• 2021

In this study, the effective dose was measured using the PCXMC v2.0 program by examining the conditions used to set the diagnostic reference level for intraoral imaging recommended by the government, and the effect of the Al additive filter was confirmed. In oral imaging, the largest effective dose was calculated from the oral mucosa among 11 organs. The effect of the Al additive filter showed an excellent radiation reduction effect at 2mm rather than 1mm. In the case of children aged 5 years, the overall effective dose was calculated to be high in all 11 organs because they are more sensitive to radiation than adults. And as a result of evaluating the image quality according to the use of an additional filter during intraoral imaging, there was no significant difference in SNR and CNR changes compared to before the additional filter was used. Based on this study, it is thought that additional filter settings can be recommended for intraoral imaging.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.421-429
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• 2020

The purpose of this study aimed to identify the relationship between department adaptation, career satisfaction and major satisfaction of the male students in department of dental hygiene and to provide basic data to improve their major satisfaction. The subjects were 102 male students attended dental hygiene departments at four universities in Seoul, Gangwon-do and Gyeongsang-do. The survey was completed a self administered questionnaire survey available on a website from September to October 2019. The collected data were analyzed frequency, mean and standard deviation, correlation and logistic regression using the SPSS 22.0 program. The questionnaire consisted of a total of 36 questions, with each item scored on a 5-point Likert scale. The mean score of male students of dental hygiene department major satisfaction was 3.32, department adaptation was 3.48 and career satisfaction was 3.08. The results of the correlation analysis shows that major satisfaction has a statistically significant positive correlation between career satisfaction and departmental adaptation(p<0.01), career satisfaction was a statistically significant positive correlation to the departmental adaptation(p<0.01). As a result of regression analysis with Independent variables such as departmental adaptation(β=0.410) and career satisfaction(β=0.457) were analyzed to have a significant positive effect on the major satisfaction(p<0.001). Accordingly, the department adaptation and job career satisfaction are critical factors for major satisfaction.

• Korean Journal of Ichthyology
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• v.32 no.4
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• pp.199-209
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• 2020

In order to clarify the taxonomic status of the Korean Macroramphosus species, which were previously confused, we investigated morphological and molecular variations of Macroramphosus (18 individuals) from Korea, and Macroramphosus (35 individuals) from Japan and Taiwan, and compared with those of M. scolopax from type locality (Mediterranean Sea). Although the Korean and Japanese specimens of Macroramphosus were clearly divided into two types in the first dorsal spine length (22.8~32.1% in A-type vs. 15.6~21.4% in B-type), distance between the first dorsal fin and second dorsal fin (6.4~9.7% vs. 8.6~13.3%), and body depth (20.0~28.0% vs. 17.3~22.6%), no genetic differences among all individuals of longspine snipefish between them were found at the specific level [d=0.0~3.3% in control region (CR); 0.0~1.3% in cytochrome b (cytb); 0.0~0.5% in cytochrome c oxidase subunit I (COI)]. Whereas, they were well distinguished in genetics (9.9~11.5% in CR; 3.8~4.6% in cytb; 1.2~3.6% in COI) from those of M. scolopax in Mediterranean Sea. It needs the scientific name of the longspine snipefish (M. scolopax) in Korea be changed as M. japonicus (and/or M. sagifue). However, our results could not find evidence of consistency between morphological and mitochondrial DNA variations which suggests that their differentiation event may occur fairly recently. Further studies using more sensitive markers such as microsatellite are needed to clarify the degree of gene flow between the two types.

• Journal of Korean Dental Hygiene Science
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• v.5 no.2
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• pp.97-104
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• 2022

Background: Due to the declining number of students preparing for university entrance exams , the quota of universities has been decreasing continuously. This situation became increasingly diverse as new media used online, mobile, and PR tools to continuously invite students. This study is aimed at offering the helpful data to plan an effective PR strategy by analyzing the correlation between the major selection and satisfaction of the department's social media usage among freshmen majoring in dental hygiene. Methods: The collected data from the self-reported survey with freshmen were analyzed using the SPSS 22.0 program. The survey items were motive to select the major, social media platform that subjects used, reasons to use the media, time to visit the department's social media platform, and satisfaction level on the department's social media platform, using a 5-point Likert Scale. Results: The reasons for choosing a major were given by 32.2% and 15.9% respondents, respectively, as the vision after graduation and practice facilities. 39.9% and 31.4% used Instagram and YouTube for social media platforms, respectively, for using social media platform; 26.9% and 26.3% visited the department's social media before and after entering the university, respectively; 46.4% and 24.9% used Instagram and YouTube for department social media; and they generally satisfied with the contents of the department's social media. 40.9% of them said that information from the department's social media was useful. 33.8% of them said the information from the department's social media exceeded their expectations. 46.8% of them answered that the department's social media made the department's image positive. 33.4% got interested in the major more due to the department's social media. According to 32.1% of respondents, the department's social media was helpful in deciding on a major. With 35.4%, a positive correlation was discovered between the department's practice facilities and satisfaction on the department's social media. Conclusion: It is thought that the department's social media should try continuously by uploading the contents to meet the users' needs on a regular basis and seeking the plans to be able to collect various opinions using surveys through the related social media so that students can select the major and, moreover, lead the positive direction to adapt the university life under the unfamiliar environment after admission.

• Journal of Korean society of Dental Hygiene
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• v.22 no.6
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• pp.485-494
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• 2022

Objectives: The COVID-19 outbreak has resulted in changes in the instructional methods used in kindergartens and daycare centers to prevent viral infections. This study aimed to investigate the changes in oral health care for children before and during COVID-19 and the perceptions of kindergarten and daycare center teachers about oral health care. Methods: The study subjects were 189 teachers of kindergartens and daycare centers in charge of children aged 3 to 5. The data for the analysis were collected through an online survey. Frequency analysis and the chi-squared test were used for statistical analysis. Results: Compared to before COVID-19, the frequency of tooth brushing after lunch, the number of oral health education and regular oral examinations, and the rate of childcare teachers' experiences with oral health education had decreased during COVID-19. In addition, educators in kindergarten and daycare centers responded that an oral health officer at a public health center was the most desirable oral health educator. Conclusions: During the COVID-19 pandemic, the oral health care of children in kindergartens and daycare centers has declined. Efforts are needed to restore it by educating people about oral hygiene care and oral health education, both at home and in kindergartens and daycare centers.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.42-51
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• 2022

Esthetic restoration of maxillary anterior implant heavily depends on the direction of installation of implant fixture. In patients with malpositioned implant, it is crucial to communicate the limitations of prosthetic outcome with the patient before starting on a restoration. To facilitate the communication, three-dimensional virtual representation by superimposing facial and intraoral digital scans with Computed Tomography (CT, dicom file) was used for visualization of the limitations of prosthesis. Through digital diagnostic wax-up, the profile of right maxillary anterior incisor implant was expected to be protrusive, which the patient was not satisfied with. Since the patient already had done root canal treatment on left maxillary anterior incisor due to previous trauma, a new prosthetic design including both right and left maxillary anterior incisors was presented to the patient. The second design was chosen and his comments were delivered to dental lab. The patient was satisfied with the new prosthesis, aesthetically and functionally.

• Journal of Life Science
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• v.34 no.4
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• pp.215-226
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• 2024

Aralia continentalis is widely distributed in Far East Asian countries such as Korea, China, and Japan. A. continentalis has traditionally been used as an herbal remedy for various conditions, including analgesia, headache, inflammation, lameness, lumbago, rheumatism, and dental diseases in Korea. Previously, epi-continentalic acid, continentalic acid, and kaurenoic acid as major active biological compounds belonging to the diterpenoid class were identified. To synthesize diterpenoid derivatives with enhanced bioavailability, Fusarium fujikuroi was employed to biotransform diterpenoids due to its known antibacterial activity. This yielded two derivatives of kaurenoic acid, namely 16α-hydroxyent-kauran-2-on-19-oic acid and 2β, 16α-dihydroxy-ent-kauran-19-oic acid, with their chemical structures elucidated via NMR analysis. These derivatives exhibited increased polarity compared to kaur- enoic acid, as evidenced by their retention time on preparative HPLC using the ODS-A column and structural modifications. Evaluation of their antidiabetic activity targeting PTP1B, a negative regulator of the insulin signaling pathway, revealed inhibitory activities of 30.8% and 27.6%, respectively, at a concentration of 4 ㎍/ml. Additionally, both derivatives demonstrated low cytotoxicity, with an IC50 value 18 times higher than kaurenoic acid. Therefore, the augmented water solubility and reduced toxicity of 16α-hydroxy-ent-kauran-2-on-19-oic acid and 2β, 16α-dihydroxy-ent-kauran-19-oic acid, resulting from biotransformation by F. fujikuroi, render them promising candidates for industrial applications.

• Journal of Korean Dental Hygiene Science
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• v.6 no.2
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• pp.101-114
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• 2023

Background: This study aimed to explore the overall perception of pit and fissure sealants and suggest methods to revitalize their current stagnation. Methods: To determine the social perception of the change in coverage policy for pit and fissure sealants, we categorized them into five time periods. The first period (December 1, 2009 to November 30, 2010), the second period (December 1, 2010 to September 30, 2012), the third period (October 1, 2012 to May 5, 2013), the fourth period (May 6, 2013 to September 30, 2017), and the fifth period (October 1, 2017 to December 31, 2022). We utilized text mining, an unstructured big data analysis method. Keywords were collected and analyzed using Textom, and the frequency analysis of the top 30 keywords, structural features of the semantic network, centrality analysis, QAP correlation analysis, and co-occurrence analysis were conducted. Results: The frequency analysis showed that the top keywords for each time period were 'Cavities', 'Treatment', and 'Children'. In the structural features of the semantic network of pit and fissure sealants by time period, the density index was found to be around 1.00 for all time periods. The QAP correlation analysis showed the highest correlation between the first and second periods and the fourth and fifth periods with a correlation coefficient of 0.834. The co-occurrence analysis showed that 'cavities' and 'prevention were the top two words across all time periods. Conclusion: This study showed that pit and fissure sealants are well accepted by the society as a preventive treatment for caries. However, the awareness of health education related to these sealants was found to be low. Efforts to revitalize stagnant pit and fissure sealants need to be strengthened with effective education.

• Journal of Korean Dental Hygiene Science
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• v.6 no.2
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• pp.1-12
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• 2023

Objectives: This study attempted to identify the eating habits and oral health behaviors of Korean teenagers, studying their relationship with oral health status. The findings serve as fundamental data to enhance proper eating habits and oral health-related projects, ultimately improving teenagers' oral health. Methods: It was analyzed through the original data of the 16th (2020) online survey of youth health behavior in Korea, Frequency analysis, complex sample cross-analysis, complex sample logistic regression analysis were conducted using the SPSSwin 21.0 program. Results: As a result of the study, was associated with the consumption of all sweet drinks, fast food intake, and the frequency of daily brushing over the past 7 days Teeth pain is noted with the consumption of soda, sweet drinks, fast food, and the frequency of daily brushing over the past 7 days. Gum bleeding is noted with the consumption of sweetened products, fast food intake, and the frequency of daily brushing over the past 7 days. Conclusions: Eating habits and oral health behaviors should be considered for the oral health management of middle and high school students. Specific measures should be sought to provide proper dietary education and systematic oral health education to improve the oral health of middle and high school students.