• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.539-544
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• 1998

Thermoformed appliance, which has been recently introduced for dental usage, is an appliance made of thermoformed sheets and formed with positive or negative pressure under heat. Thermoplastic material is a kind of plastics and can be repeatedly softened by heat. It is classified into hard elastic foil, hard/soft compound foil and soft elastic foil, including BIOPLAST, BIOCRYL, IMPRELON, etc. It has been developed in 1969 and is available in various thickness, shape and color. There are two types of Vacuum former for thermoplastic materials; the pressure type and suction type. The former is much better than the latter for fabrication of various appliances due to its higher pressure. The authors have applied these appliances to some cases - chin cap, active retainer, individual Fluoride tray, mouth protector, bracket transfer mask, bruxism splint(night guard), Essix appliance - by pressure type Vacuum former($Biostar^{(R)}$). The thermoplastic appliances have numerous advantages such as simple procedure, short working time, clean and transparent product, less objectionable taste. But its outstanding advantage would be its excellent biocompatibility bacause it has no monomer and hence no tissue irritation. Although there is some limitations in its usage, it can be used widely for various purposes especaily for pediatric dentistry.

• Korean Journal of Health Education and Promotion
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• v.25 no.1
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• pp.71-81
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• 2008

Objectives: The purpose of this study was to evaluate the long term effects of school-based oral health program on the decrease of dental caries among elementary school children. Methods: The subjects of this study were total 283 students of one elementary school in Deagu, Korea. They had received school-based oral health programs more than one year since 2004. This school-based oral health program included regular oral examination, fluoride mouthrinsing, pit-and-fissure sealing, APF gel application, tooth brushing instruction and chewing the xylitol tablets. The subjects' oral health status were examined and calibrated by a dentist every year from 2004 to 2007. Results: The change of DMFT index were as follows: (1)The subjects who entered the school at 2004 - 0.32(2004), 0.25(2005), 0.25(2006) and 0.38(2007), (2)the subjects who entered the school at 2005 - 0.18(2005), 0.31(2006) and 0.32(2007), and (3)the subjects who entered the school at 2006 - 0.19(2006) and 0.27(2007). Conclusions: This study partially showed the effects of school-based oral health programs on the increments of dental caries. This programs should be expanded widely among elementary schools in Korea.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.181-185
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• 2020

Hazardous and noxious substance (HNS) detection sensors were fabricated using multi-walled carbon nanotubes (MWCNTs) and various binder materials for ion batteries. To obtain uniformly printed films, the printing precision according to the substrate cleaning method was monitored, and the printing paste mixing ratio was investigated. Binders were prepared using styrene butadiene rubber + carboxymethyl cellulose (SBR+CMC), polyvinylidene fluoride + n-methyl-2-pyrrolidene (PVDF+NMP), and mixed with MWCNTs. The surface morphology of the printed films was examined using an optical microscope and a scanning electron microscope, and their electrical properties are investigated using an I-V sourcemeter. Finally, sensing properties of MWCNT printed films were measured according to changes in the concentration of the chemical under the various applied voltages. In conclusion, the MWCNT printed films made of (SBR+CMC) were found to be feasible for application to the detection of hazardous and noxious chemicals spilled in seawater.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.109-115
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• 2013

This study targeted 501 the elderly ages 65 or over in three places including the Senior Welfare Center and the college for seniors located in Daegu City and Gyeongsangbuk-do. The study results on the preference for oral health care management items across different ages showed that the age group of 65~69 fluoride application; the age group of 65~74 scaling and education of brushing; the age group of 70~74 denture cleaning and maintenance; the age group of 75 denture production. In the relationship between the self-perceived oral condition and the items of oral health care management, respondents who currently have a poor oral condition or have greater chewing trouble, or have higher dry mouth, preference the manufacturing of dentures in most cases. Respondents who have a lower number of teeth or wear dentures preference dentures cleansing and management in most cases. Respondents who have shaking teeth or have frequent tooth pain preference tooth extraction. Since the preference for oral health care management items may differ by their age or oral condition, oral health management customized to each individual should be applied.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.641-659
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• 2010

Structural Health Monitoring (SHM) gradually becomes a technique for ensuring the health and safety of civil infrastructures and is also an important approach for the research of the damage accumulation and disaster evolving characteristics of civil infrastructures. It is attracting prodigious research interests and the active development interests of scientists and engineers because a great number of civil infrastructures are planned and built every year in mainland China. In a SHM system the sheer number of accompanying wires, fiber optic cables, and other physical transmission medium is usually prohibitive, particularly for such structures as offshore platforms and long-span structures. Fortunately, with recent advances in technologies in sensing, wireless communication, and micro electro mechanical systems (MEMS), wireless sensor technique has been developing rapidly and is being used gradually in the SHM of civil engineering structures. In this paper, some recent advances in the research, development, and implementation of wireless sensors for the SHM of civil infrastructures in mainland China, especially in Dalian University of Technology (DUT) and Harbin Institute of Technology (HIT), are introduced. Firstly, a kind of wireless digital acceleration sensors for structural global monitoring is designed and validated in an offshore structure model. Secondly, wireless inclination sensor systems based on Frequency-hopping techniques are developed and applied successfully to swing monitoring of large-scale hook structures. Thirdly, wireless acquisition systems integrating with different sensing materials, such as Polyvinylidene Fluoride(PVDF), strain gauge, piezoresistive stress/strain sensors fabricated by using the nickel powder-filled cement-based composite, are proposed for structural local monitoring, and validating the characteristics of the above materials. Finally, solutions to the key problem of finite energy for wireless sensors networks are discussed, with future works also being introduced, for example, the wireless sensor networks powered by corrosion signal for corrosion monitoring and rapid diagnosis for large structures.

• Journal of Korean society of Dental Hygiene
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• v.21 no.4
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• pp.441-453
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• 2021

Objectives: This study identified problems and improvements in projects targeted to dental workers in a child-adolescent dental care service. Methods: The subjects were 40 dentists, 43 dental hygienists, and 51 others who participated in service in Seoul. A self-administered questionnaire was used to address the problems and improvements in the project. Descriptive statistics, chi-square test, and one-way analysis of variance were performed using SPSS 23.0. Results: Oral examination was performed by 99.2% of dentists, and some service items such as professional tooth cleaning, fluoride application, and scaling were performed by dental auxiliary personnel regardless of legal duties. The problem was that the subjects took a lot of time in providing services, and students or guardians participating in the project refused to receive preventive dental services. As regards improvements, the insurance fee was the highest (48.1%), followed by the provision of regular services (38.8%), and system improvement and administrative support (35.7%). Conclusions: To activate a child-adolescent dental care service, it is thought that continuous efforts such as providing financial support by the government, education to increase participants' understanding, and social consensus for the participation of service providers and beneficiaries are required.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.52-59
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• 2022

Decalcification of the buccal surface of the teeth often occurs during fixed orthodontic treatment. This case report describes two cases in which cervical decalcificated teeth that occurred during orthodontic treatment were treated with direct resin veneer restoration. Early lesions without caries can be remineralized through periodic fluoride application, diet control, and oral hygiene improvement. As it progresses, appropriate repair treatment is required, and it is more preferable to focus on prevention rather than treatment after the occurrence of the lesion.

• Journal of dental hygiene science
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• v.22 no.1
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• pp.44-50
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• 2022

Background: This study compares and analyzes the degree of oral health information literacy by 25% for upper and lower grades to assess how differences in mothers' oral health information literacy affect infants' oral health behavior. Methods: The study surveyed 201 mothers with infants and children using a 36 question survey tool. Cross-analysis was conducted to determine the difference in oral health information literacy between the upper and the lower 25%. Results: Comparing 25% of the upper and lower grades of verbal oral health information literacy scores, the word with the most significant difference in the correct answer was resin. An item asking about the time to eat after fluoride varnish application showed the most significant difference in the correct answer on the functional oral health information literacy scale. Mothers' oral and functional oral health information literacy scores showed that verbal literacy was statistically significant for brushing guidance after children's meals, brushing guidance before children's bedtime, food intake restrictions before bedtime, and restrictions on consumption of cavity-inducing foods (p<0.05). Functional literacy was statistically significant in the post-brushing test of children and the correct brushing method map items (p<0.05). Conclusion: As a result of comparing and analyzing the upper and lower 25% of the mother's oral health information literacy, it was found that the mother's oral health information literacy affected the infant's oral health behavior. Therefore, systematic education is needed to raise literacy by grasping the level of oral health information literacy of mothers, and oral health education by level according to oral health information literacy should be developed.

• The Journal of the Acoustical Society of Korea
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• v.25 no.4
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• pp.164-171
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• 2006

If the velocities of longitudinal, transverse and leaky surface acoustic waves in an isotropic material are given, the elastic constants and density of the material can be deduced analytically. Those velocities have been measured using three ultrasonic transducers with different vibrational modes so far. In this paper a line-focusing PVDF transducer with divided electrodes was newly proposed and designed for measuring approximate velocities of the three waves. The measurement method established in this study for each waves using the transducer was applied to several isotropic materials including fused quartz. The elastic stiffness constants and densities of the materials were calculated using the measured velocities, and the accuracies were discussed. It was shown that the obtained results are in good accord with the reference values.

• Advances in materials Research
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• v.13 no.3
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• pp.153-160
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• 2024

This study investigates the application of alternating current (AC) and direct current (DC) anodization techniques on stainless steel 304L (SS304L) in an ethylene glycol and ammonium fluoride (NH4F) electrolyte solution to produce a nano-porous oxide layer. With limited research on AC anodizing of stainless steel, this study focuses on comparing AC and DC anodization in terms of current density versus time response, phase analysis using X-ray diffraction (XRD), and corrosion rate determined by linear polarization. Both AC and DC anodization were performed for 60 minutes at 50 V in an electrolyte solution containing 0.5% NH4F and 3% H₂O in ethylene glycol. The results show that AC anodization exhibited higher current density compared to DC anodization. XRD analysis revealed the presence of ferrite (α-Fe) and austenite (γ-Fe) phases in the as-received specimen, while both AC and DC anodized specimens exhibited only the γ-Fe phase. The corrosion rate of the AC-anodized specimen was measured at 0.00083 mm/year, lower than the corrosion rate of the DC-anodized specimen at 0.00197 mm/year. These findings indicate that AC anodization on stainless steel offers advantages in terms of higher current density, phase transformation, and lower corrosion rate compared to DC anodization. These results highlight the need for further investigation and exploration of AC anodization as a promising technique for enhancing the electrochemical properties of stainless steel.