• The Journal of Korean Academy of Prosthodontics
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• v.39 no.2
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• pp.208-219
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• 2001

To study the effect of dentin permeability on a tooth with wear from tooth brushing after application of desensitizing agent, extracted teeth free from caries were chosen. Coronal dentin discs with thickness of 1mm were prepared. Using the split chamber device developed by Pashely, hydraulic conductance, scanning electron microscope images(SEM) and atomic force microscope images(AFM) were compared and contrasted before and immediately after the application of desensitizing agent and after equivalent tooth brushing of 1 week, 2 weeks, and 6 weeks. Four commercially available desensitizing agents were used in this study ; they were Gluma, Seal & Protect, All-Bond 2 and MS Coat. The results of this study are as follows. 1. On all specimens, the hydraulic conductance decreased after the application of tooth desensitizing agent. 2. Except the specimens treated with MS Coat, the remaining specimens had an increase in dentin permeability after tooth brushing for 1 and 2 weeks but a decrease after 6 weeks. 3. The specimens treated with MS Coat had statistically significant increase in the dentin permeability regardless with the duration of tooth brushing. 4. On examination of SEM and AFM, the dentinal tubule diameter had decreased after treatment of desensitizing agents. The specimens other than those treated with MS Coat, smear layers were noted after tooth brushing. It is not always consistant but the hydraulic conductance correlated with the images from SEM and AFM.

• Journal of Preventive Medicine and Public Health
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• v.52 no.5
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• pp.333-343
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• 2019

Objectives: This study aimed to evaluate the association between dental implants and cognitive function in community-dwelling older adults. Methods: Data were collected from the baseline survey (2016-2017) of the Korean Frailty and Aging Cohort Study. The study sample comprised 1115 community-dwelling people aged 70 years to 84 years who had 0-19 natural teeth. Dental implants and natural teeth were identified by panoramic radiography, while the cognitive function was assessed by the Korean version of the Mini-Mental State Examination (MMSE-KC). The association between dental implants and cognitive function was analyzed by multiple linear regression. Sensitivity analysis was performed to test for potential bias. Results: The mean number of natural teeth in the study population was 9.50 (standard deviation [SD], 6.42), and the mean MMSE-KC score was 24.93 (SD, 3.55). In the simple univariate analysis, tooth replacement, age, sex, smoking status, alcohol consumption, body mass index, osteoporosis, number of natural teeth, periodontitis, chewing discomfort, tooth-brushing frequency, education level, monthly household income, participation in economic activity, living alone, and marital status had a significant impact on the association. After adjusting for confounders, the association between dental implants and cognitive function remained significant (B, 0.85; standard error, 0.40; p<0.05). Age, body mass index, periodontitis, tooth-brushing frequency, and education level were also significantly associated with cognitive function. The results of the sensitivity analyses were consistent with those of the primary analysis. Conclusions: Dental implants were associated with cognitive function in older adults living in the community. Dental implants as tooth replacements may play a role in preserving cognitive function.

• Journal of Veterinary Clinics
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• v.23 no.4
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• pp.476-479
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• 2006

A 9-year-old, female Yorkshire terrier and a 10-year-old, female Maltese were referred to the Veterinary Medical Teaching Hospital of Konkuk University. The dogs were presented with severe swelling and cutaneous sinus tract on the left suborbital lesion. Under general anesthesia, we performed physical, intraoral examinations and survey radiography, and diagnosed as periapical abscess in a left fourth premolar tooth. They were treated with tooth extraction, and the sinus tracts were drained with 0.05% chlorhexidine solution. After teeth extractions, medication applied by the result of antibiotic sensitivity test. During follow-up 10 months later, the left suborbital swelling had completely resolved.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.7 s.361
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• pp.31-36
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• 2007

A saw-tooth waveform generator whose frequency can be controlled with a do bias current is proposed. The generator utilizes operational transconductance amplifiers (OTA's) as switching element. It features simple and wide sweep capability The circuit built with commercially avaliable components exhibits good linearity of current-to-frequency transfer characteristics and relatively low temperature sensitivity.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.7
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• pp.611-617
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• 2015

In the development of a vibration-based condition monitoring system in gearbox, one of the most important research topics is a quantitative analysis and test of the effect of gear damage on vibration of gearbox. This paper presents the evaluation result of vibration condition indicator according to the gear tooth damage through the vibration test of gearbox. The dynamic load test was performed with high speed railway (KTX)'s gearbox. The vibration of gearbox was measured according to a rotational speed change with the common gear fault modes, such as pitting and tooth breakage. The characteristics and the possibility of applying of vibration condition indicator on condition monitoring system were analyzed. As a result, the value of most condition indicator is gradually increased with the severity of gear faults. The NA6 indicator shows a low variation with the rotational speed change and high sensitivity in accordance with the gear fault.

• Journal of Korean Dental Hygiene Science
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• v.4 no.2
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• pp.67-75
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• 2021

Background: Workers' oral health problems result in work disruption, including absenteeism or early leave, which reduces work efficiency. This study was conducted to investigate the subjective oral health status and oral problems of workers,and to identify the factors disrupting workflow due to oral problems. Methods: A self-report questionnaire was administered to 300 industrial workers in a metropolitan area. A total of 284 individuals were finally analyzed, after excluding the data of 16 workers who had missing responses among the recovered questionnaires. Results: Subjective oral health status was average in 44.4%, healthy in 32.0%, and unhealthy in 16.9% of the study population. Subjective oral health problems were the highest in the order of food impaction(28.9%), cavity(26.8%), tooth sensitivity (22.9%), and calculus(21.1%). However, sudden and unexplained tooth pain (12.0%), gum swelling and tooth mobility (10.2%), and wisdom tooth pain (4.9%) were relatively low. The average monthly income (p<.05) and subjective oral health status (p<.01) were statistically significant factors interrupting workflow. Conclusion: To minimize workers' oral health problems and work disruption due to oral diseases, it is necessary to promote workers' oral health and oral disease prevention programs within the workplace.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.352-352
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• 2002

• Journal of Korean society of Dental Hygiene
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• v.16 no.1
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• pp.85-92
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• 2016

Objectives: The purpose of this study was to investigate comparison of the effectiveness on knowledge improvement before and after the oral health education focusing on foreign students. Methods: A self-reported questionnaire was filled out by 40 foreign students in Sun Moon University from June 2 to September 30, 2014. The experimental group had an online oral health education and the control group had an off line education. The questionnaire consisted of oral health(10 items), toothbrushing(10 items), dental caries(10 items), periodontal disease(5 items), tooth sensitivity(5 items), oral cancer(6 items), and smoking(5 items). The data were analyzed by SPSS Win 18.0 program. Results: Knowledge scores of online education increased to average 1.257 points, and that of offline education was average of 2.56 points. There were statistically significant results for toothbrushing, dental caries, periodontal disease, tooth sensitivity, oral cancer and TMD except for smoking in offline education group. Conclusions: This study suggests that the offline oral health education is more effective than online oral health education.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1623-1630
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• 2010

In this study, effective forming methods for reducing the roll-over of a sector tooth, which is a main component of an automotive seat recliner, are proposed. Due to the large amount of roll-over, accurate contact between the inner gear of a sector tooth and the outer gear of a pawl tooth cannot be normally achieved; thus sensitivity and safety for the passengers decrease. To overcome the aforementioned drawback, we investigated the effect of flowcontrol forming methods involving local embossing die, coining punch, and VIC (Variable Inverse Clearance) on the roll-over depth by FE-analysis and an experiment. The results of a fine-blanking experiment for verifying the proposed methods showed that VIC type is decidedly superior from the aspects of reduction of roll-over and tool strength of the sector tooth.

• Imaging Science in Dentistry
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• v.44 no.1
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• pp.37-41
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• 2014

Purpose: The aim of this study was to investigate the accuracy of cone-beam computed tomography (CBCT) in the diagnosis of vertical root fractures in a tooth with gutta-percha and prefabricated posts. Materials and Methods: This study selected 96 extracted molar and premolar teeth of the mandible. These teeth were divided into six groups as follows: Groups A, B, and C consisted of teeth with vertical root fractures, and groups D, E, and F had teeth without vertical root fractures; groups A and D had teeth with gutta-percha and prefabricated posts; groups B and E had teeth with gutta-percha but without prefabricated posts, and groups C and F had teeth without gutta-percha or prefabricated posts. Then, the CBCT scans were obtained and examined by three oral and maxillofacial radiologists in order to determine the presence of vertical root fractures. The data were analyzed using IBM SPSS 20.0 (IBM Corp., Armonk, NY, USA). Results: The kappa coefficient was $0.875{\pm}0.049$. Groups A and D showed a sensitivity of 81% and a specificity of 100%; groups E and B, a sensitivity of 94% and a specificity of 100%; and groups C and F, a sensitivity of 88% and a specificity of 100%. Conclusion: The CBCT scans revealed a high accuracy in the diagnosis of vertical root fractures; the accuracy did not decrease in the presence of gutta-percha. The presence of prefabricated posts also had little effect on the accuracy of the system, which was, of course, not statistically significant.