• 한국광학회지
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• 제20권5호
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• pp.301-307
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• 2009

액정표시장치의 고효율 백라이트 집광시트로 활용하기 위하여 배면 개구형 집광시트를 설계 및 분석하였다. Microlens array sheet, 피라미드 array sheet, 그리고 cone array sheet에 대해서 자체 정렬에 의한 배면 개구 형성 특성을 비교 분석한 결과, microlens array sheet가 가장 우수하였고, 다음으로 피라미드 array sheet였으며, cone array sheet가 가장 부적합하였다.

• Imaging Science in Dentistry
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• 제41권4호
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• pp.155-159
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• 2011

Purpose : This study was performed to determine the prevalence of maxillary canine impaction on a basis of a single panoramic radiograph in Bangladeshi population. Materials and Methods : A random sample of seven hundred panoramic radiographs was collected from the patient record of a dental clinic. All the selected panoramic radiographs were taken from January 2009 to August 2010 by a single panoramic radiograph machine with the same exposure time (19 seconds) for all radiographs. One hundred and twenty panoramic radiographs were excluded to minimize the selection bias. In a dim lit room, an observer assessed the radiographs on a standard radiographic light box. The position of the impacted maxillary canine was recorded in line with the longitudinal axis of a tooth using the edge of a metal ruler. Data were subsequently put on SPSS 11.5 software and chi-square (${\chi}^2$) tests were applied to find out the association. Results : Among 580 panoramic radiographs it was found that impacted maxillary canines were present in only 7 (1.2%) radiographs. A statistical significant difference was found between the age of the patients and the vertical position of the impacted canines (p=0.000) and between the age of the patients and the horizontal position of the impacted canines (p=0.003). Conclusion : The prevalence was found to be low compared with the present study from the limitation of panoramic image. Further study needs to include three-dimensional imaging modality.