• 한국철도학회논문집
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• 제14권4호
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• pp.348-353
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• 2011

레일을 궤도회로로 이용하는 신호 설비의 경우, 레일 주변에 쌓이는 쇠가루는 궤도회로 상에 이상 신호유발의 원인이 되기도 한다. 차량의 곡선 주행 구간에서는 레일과 차륜의 마찰이 심하여 차륜의 마모에 의한 쇠가루가 발생하게 되고, 이렇게 발생한 레일 상의 쇠가루로 인해 이상 신호가 종종 발생하기 때문에 지하철 운영사의 쇠가루 제거를 위한 방안 마련이 시급한 실정이다. 본 연구에서는 콘크리트 궤도 상 레일 주변의 쇠가루를 포집하기 위한 영구자석 적용 마그넷 포집장치를 소개하였다. 또한 기본 설계 및 수치 해석적 기법을 이용하여 마그넷 포집장치의 다양한 특성 분석을 수행하였으며, 이를 통하여 콘크리트 궤도상의 쇠가루 포집을 위한 마그넷 포집장치의 실제 상용노선 차량에의 적용 가능성을 검토하였다.

• 대한치과의사협회지
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• 제21권2호통권165호
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• pp.167-172
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• 1983

This study was to investigate the effects of mynol cement on the periapical tissues of 40 molars in ten dogs. Root canal fillings were placed with mynol cement and the animals were killed at different post operative periods ranging from 1 to 5 weeks. The teeth examined on the basis of microscipic findings. The following results may be drawn; 1. 1 week after root canal fillings, the necrosis of cementum and dentin including alveolar bone was to be seen. There were severe inflammatory changes in the periodontal ligament. 2. 2 weeks after root canal fillings, edematous changes and fibrosis in the periodontal ligament were revealed. 3. After 3-4 weeks, fibrosis was more prominent than 2 weeks. 4. 5 weeks after root canal fillings, the osteoblastic activity was found abundantly surrounding the alveolar bone.

• 호남수학학술지
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• 제32권1호
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• pp.73-76
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• 2010

In this paper we investigate the distances between Dehn fillings on a hyperbolic 3-manifold that yield 3-manifolds containing a M$\"{o}$bius band and a Klein bottle.

• 대한수학회보
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• 제60권1호
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• pp.113-122
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• 2023

We classify lens spaces with the Milnor fillable contact structure that admit minimal symplectic fillings whose second Betti numbers are one.

• 한국터널지하공간학회 논문집
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• 제25권2호
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• pp.141-155
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• 2023

전기비저항을 이용한 모니터링 기술은 비파괴적으로 데이터 수집이 가능하여, 터널 및 지하구조물의 건전도 평가를 목적으로 활발히 활용되고 있다. 터널 시공에서 단층파쇄대와 같은 취약 구간은 지반의 변위 발생 및 응력 변화 등의 문제를 일으킨다. 따라서 터널 구조물의 역학적 안정성 확보를 위해 단층파쇄대 구간의 절리 상태 예측이 필요하다. 절리의 크기 및 충진물의 공극률 모니터링은 암반의 절리 상태 예측을 위해 필수적이다. 하지만 기존 연구에서는 자연상태의 암반절리 내 입자 크기의 다양성을 고려하지 못한 한계가 있다. 따라서 본 연구에서는 암반절리 상태 충진물의 조립토 입자혼합상태에 따른 전기비저항 실험을 수행하였다. 실험 결과, 동일한 공극률 조건에서 충진물의 크기가 작을수록 전기비저항 값이 증가하는 경향성을 확인하였다. 본 연구결과는 터널 구간 내 암반절리 내 조립토 충진물을 포함하고 있는 지반의 전방 예측 및 거동 평가를 위한 전기비저항 기초자료로 유용하게 활용될 것으로 기대된다.

• The Journal of Advanced Prosthodontics
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• 제6권4호
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• pp.278-284
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• 2014

PURPOSE. There is insufficient data regarding the durability of porcelain laminate veneers bonded to existing composite fillings. The aim of the present study was to evaluate the fracture resistance and microleakage of porcelain laminate veneers bonded to teeth with existing composite fillings. MATERIALS AND METHODS. Thirty maxillary central incisors were divided into three groups (for each group, n=10): intact teeth (NP), teeth with class III composite fillings (C3) and teeth with class IV cavities (C4). Porcelain laminate veneers were made using IPS-Empress ceramic and bonded with Panavia F2 resin cement. The microleakage of all of the specimens was tested before and after cyclic loading ($1{\times}10^6$ cycles, 1.2 Hz). The fracture resistance values (N) were measured using a universal testing machine, and the mode of failure was also examined. The statistical analyses were performed using one-way ANOVA and Tukey post hoc tests (${\alpha}=.05$). RESULTS. There was a significant difference in the mean microleakage of group C4 compared with group NT (P=.013). There was no significant difference in the fracture loads among the groups. CONCLUSION. The microleakage and failure loads of porcelain laminate veneers bonded to intact teeth and teeth with standard class III composite fillings were not significantly different.

• 대한치과의사협회지
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• 제18권9호통권136호
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• pp.739-745
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• 1980

The histologic responses of periapical tissues to root canal fillings with Grossman sealer were studied 10 dogs. Root canal fillings were performed on the 20 lower and upper teeth. The animals were sacrificed 1,2,3,4 and 5 weeks after the completion of operation. The following results were based on histopathologic studies; 1) After 1 week, the necrosis of dentin and cementum surrounding root apex was found in the root canal fillings. 2) After 2 weeks, the necrosis of cementum and surrounding alveolar bone were revealed. The resorption of dentin was appeared partially. 3) After 2 weeks, newly formed dentin was appeared surrounding necrotic dentin. 4) After 4-5 weeks, the osteoblastic activity was revealed abundantly surrounding the alveolar bone. 5) Fibrosis was prominantly appeared surrounding over-filled area, and fibrous encapsulation was performed.

• Imaging Science in Dentistry
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• 제53권3호
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• pp.199-207
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• 2023

Purpose: The objective of this study was to evaluate the accuracy and effectiveness of an artificial intelligence (AI) program in identifying dental conditions using panoramic radiographs(PRs), as well as to assess the appropriateness of its treatment recommendations. Materials and Methods: PRs from 100 patients(representing 4497 teeth) with known clinical examination findings were randomly selected from a university database. Three dentomaxillofacial radiologists and the Diagnocat AI software evaluated these PRs. The evaluations were focused on various dental conditions and treatments, including canal filling, caries, cast post and core, dental calculus, fillings, furcation lesions, implants, lack of interproximal tooth contact, open margins, overhangs, periapical lesions, periodontal bone loss, short fillings, voids in root fillings, overfillings, pontics, root fragments, impacted teeth, artificial crowns, missing teeth, and healthy teeth. Results: The AI demonstrated almost perfect agreement (exceeding 0.81) in most of the assessments when compared to the ground truth. The sensitivity was very high (above 0.8) for the evaluation of healthy teeth, artificial crowns, dental calculus, missing teeth, fillings, lack of interproximal contact, periodontal bone loss, and implants. However, the sensitivity was low for the assessment of caries, periapical lesions, pontic voids in the root canal, and overhangs. Conclusion: Despite the limitations of this study, the synthesized data suggest that AI-based decision support systems can serve as a valuable tool in detecting dental conditions, when used with PR for clinical dental applications.

• Journal of Yeungnam Medical Science
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• 제40권4호
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• pp.373-380
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• 2023

Background: The association between dental amalgam fillings and urine mercury concentrations was investigated in this study to assess the health risks associated with dental amalgams. Methods: This cross-sectional study included 99 women in their 20s who visited the dental clinic in Daegu, Korea. The 99 participants were composed of 68 subjects who had dental amalgam fillings (exposure group) and 31 subjects who did not have dental amalgam fillings (nonexposure group). Oral examinations were conducted by a single dental hygienist, sociodemographic features were investigated as confounding variables, and urine mercury concentrations were measured using an automatic mercury analyzer. Results: The mean±standard deviation of the urine mercury concentrations of the exposure and nonexposure groups were 1.50±1.78 ㎍/g creatinine and 0.53±0.63 ㎍/g creatinine, respectively. The exposure group showed significantly higher levels than the nonexposure group (p<0.01). The urine mercury concentration significantly increased with an increase in the number of teeth filled with amalgam, cavity surfaces involved, and number of defective amalgam fillings, and according to the latest exposure time (p<0.001). In the multiple regression analysis of amalgam-related factors and urine mercury concentrations after correction for confounding factors, the urine mercury concentration in the group with six or more amalgam-filled teeth, 11 or more cavity surfaces, and two or more defective amalgams was significantly higher than that in the nonexposure group (p<0.001). Conclusion: According to this study, exposure to dental amalgams was confirmed to significantly affect urine mercury concentrations.

• 한국치위생학회지
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• 제21권1호
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• pp.89-98
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• 2021

Objectives: The purpose of this study was to investigate the perception and satisfaction of caregivers and parents after being covered by health insurance for light-curing composite resin fillings, and to contribute to the settlement of the expansion and coverage of health insurance. Methods: A survey was conducted on caregivers who visited two dental institutions in the Gyeonggi-do area, and parents who joined internet cafes (online communities) in the Gyeonggi-do area from June 2 to September 2, 2020. 225 responses were collected eventually, and 212 valid responses were used as analysis data. Results: 67.0% of the study subjects were aware of the permanent teeth resin fillings being covered by health insurance and the satisfaction was relatively high (91.5%). There was a statistically significant difference in the perception of permanent tooth resin filling benefits according to the child's oral condition (p=0.025) and the parents' own interest in oral health (p=0.039). Conclusions: Based on the results of this study, it is necessary to increase the accessibility to the initial treatment for dental care of children through active promotion of detailed items of permanent teeth resin fillings.