• Restorative Dentistry and Endodontics
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• 제43권3호
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• pp.31.1-31.7
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• 2018

Despite considerable focus on the regenerative endodontic treatment of immature teeth with necrotic infected pulps and apical periodontitis, little data exist with regard to its possible implementation in necrotic permanent teeth with complete apical and radicular development. The present report describes the procedures and outcome of a regenerative endodontic treatment approach in 2 previously-traumatized incisors with closed apex with apical periodontitis. A 2-visit treatment procedure was employed. At initial visit, the root canals were copiously irrigated, followed by placement of a triple antibiotic paste containing ciprofloxacin, metronidazole, and clindamycin into the root canals. After 4 weeks, the antibiotic paste was removed, and apical bleeding was initiated with size 10 hand files beyond the apices. The root canals were coronally sealed with mineral trioxide aggregate, and the access cavities were restored with bonded resin composite. At post-operative 60 months, both teeth were remained asymptomatic, with the recall radiographs showing complete resolution of apical radiolucency and reestablishment of periradicular tissues. In both teeth, the dimensions of root space remained unchanged as verified by image analysis. The revitalization protocol utilizing root canal disinfection and induced apical bleeding in necrotic, closed-apex incisors may offer a clinically acceptable alternative to conventional root canal treatment.

• 대한소아치과학회지
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• 제48권4호
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• pp.449-459
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• 2021

이 연구는 재생근관치료 결과에 영향을 줄 것으로 예상되는 인자를 후향적으로 분석하였다. 2011년 2월부터 2020년 1월까지 외상과 치외치 파절로 항생제 복합제제를 사용하여 재생근관치료를 시행한 54명의 환자와 57개의 치아를 대상으로 하였다. 의도적 출혈 여부, 치료원인, 치근발육단계에 따른 재생근관치료 결과를 분석하였다. 치료 결과는 증상의 개선, 치근단병소의 변화, 치근성장량을 토대로 판단하였다. 영상 촬영각도 및 위치에 의한 왜곡을 보정하기 위해 Turboreg plugin을 사용하였고, ImageJ softeware상에서 치근단공 크기, 치근면적, 치근길이의 변화를 측정하였다. 의도적 출혈 유무는 치료 결과에 유의한 영향이 없었다. 외상으로 인한 경우 치외치 파절로 인한 경우보다 치근면적과 치근길이의 증가가 적었다. 치근발육이 덜 진행된 치아일수록 치근면적의 성장이 크게 나타났다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.572-576
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• 1997

X-ray laminography and DT(digital tomosynthesis) that can form a cross-sectional image of 3-D objects promise to be good solutions for inspecting interior defects of industrial products. The major factors of the digital tomosynthesis that influence on the quality of x-ray cross-sectional images are also discussed. The quality of images acquired from the DT system varies according to image synthesizing methods, the number of images used in image synthesizing, and X-ray projection angles. In this paper, a new image synthesizing method named 'log-root method' is proposed to get clear and accurate cross-sectional images, which can reduce both artifact and blurring generated by materials out of focal plane. To evaluate the quality of cross-sectional images, two evaluating criteria: (1) shape accuracy and (2) clearness in the cross-sectional image are defined. Based on this criteria, a series of simulations were performed, and the results show the superiority of the new synthesizing method over the existing ones such as averaging and minimum method.

• 한국멀티미디어학회논문지
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• 제8권12호
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• pp.1565-1571
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• 2005

Images reconstructed with Maximum-Likelihood Expectation-Maximization (MLEM) algorithm have been observed to have checkerboard effects and have noise artifacts near edges as iterations proceed. To compensate this ill-posed nature, numerous penalized maximum-likelihood methods have been proposed. We suggest a simple algorithm of applying edge detecting process to the MLEM and Bayesian Expectation-Maximization (BEM) to reduce the noise artifacts near edges and remove checkerboard effects. We have shown by simulation that this algorithm removes checkerboard effects and improves the clarity of the reconstructed image and has good properties based on root mean square error (RMS).

• Radiation Oncology Journal
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• 제18권4호
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• pp.345-354
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• 2000

목적 : 방사선조사야를 확인하는 보편적인 방법인 linacgram은 저대조도(low contrast)의 영상을 보여주고 있어 정확한 영상을 확인하는데 문제점이 있다. 따라서 본 연구는 linacgram의 대조도를 높이는 저가형 확인방법을 모색하여 영상판독과 조사야 확인에 도움이 되고자 한다. 대상 및 방법: 인체모형을 사용하여 얻어진 필름 영상을 필름전용 스캐너(Diagnostic Pro)를 통해 Optical Density Scan, Histogram Equalized, Linear Histogram Based (HB), Linear Histogram Independent, Linear Optical Density (OD) Logarithmic 및 Power, Square Root scan 방식으로 디지털화 하였다. 각기 다른 방식으로 전산 입력된 영상의 신호분포도를 얻어 signal intensity를 비교한 후 pailette fitting 방식을 통해 영상을 재구성하였고 재구성된 영상을 비교 분석하였다. 실제 치료에서 얻어진 각 인체 부위별 linacgram도 동일한 방법으로 처리한 후 화질 개선도를 알아 보았다. 결과 : 인체모형을 통해 얻어진 영상의 신호 분포영역은 Logarlthmic 방식을 선택했을 때 최소값인 3192가 나왔고 Square Root방식을 사용했을 때 최대값인 21940가 나왔다. 이러한 값들을 모니터 상에서 구현할 수 있는 256 gray scale로 바꾸어 보았을 때 7$\~$30$\%$ 만 사용되어지고 있음을 알수 있었다. Pallette fitting 방식을 통하여 모니터의 최대표현 값인 256 계조도로 Gray Scale Expansion (GSE) 함으로써 모니터가 지원하는 8bit gray scale pallette의 전범위를 사용하여 대조도가 개선되었다. 임상에서 얻어진 각 인체 부위별 무릎관절, 두경부, 폐, 골반영상에서도 GSE 처리하여 얻어진 영상이 해부학적 구조를 판독하는데 도움이 죄었다. 결론 : GSE 영상의 재구성은 대조도를 증가 시킬뿐 아니라 인체내 관심부위의 농도분포를 별도로 재구성할 수 있으므로 이중방사선조사(double exposure)에 의해 발생되는 화질의 저하를 보정함으로써 화질 개선을 가능하게 하였다. Linacgram 화질 개선은 simulation image 및 치료계획에서 발생한 DRR과 multi-layer 중첩영상 분석에 사용할 수 있으며 영상 비교 시 치료부위의 신속하고 정밀한 확인을 가능하게 하였다.

• 대한의용생체공학회:의공학회지
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• 제25권1호
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• pp.33-41
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• 2004

다양한 의학 영상장비로부터 획득된 영상들간의 정합의 정확성은 방사선치료계획에서 매우 중요한 쟁점 중의 하나이다. 본 연구에서는 수제작된 뇌팬톰(brain phantom)을 이용한 영상정합의 정확성 평가방법을 연구하였다. 다중영상정합을 위해 CT-MR, CT-SPECT간의 Chamfer 정합(Chamfer matching)법을 적용하였다 영상정합의 정회성은 팬톰 내에 삽입된 표적(target)들의 중심정의 비교를 통하여 평가되었다. CT-MR, CT-SPECT간의 삼차원 제곱근평균제곱(root-mean-square) 이동편차는 각각 2.1$\pm$0.8 mm와 2.8$\pm$1.4 mm이었다. 회전편차는 세 직교좌표축에서 2$^{\circ}$이내였다. 이 오차들은 기존의 팬톰연구와 비교하여 합리적인 오차 허용범위 내에 들었다. 중첩한 CT-MR, CT-SPECT영상의 육안검증 또한 좋은 정합 결과를 보였다.

• 반도체디스플레이기술학회지
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• 제22권1호
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• pp.129-133
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• 2023

Image compression is a fundamental technique in the field of digital image processing, which will help to decrease the storage space and to transmit the files efficiently. Recently many deep learning techniques have been proposed to promise results on image compression field. Since many image compression techniques have artifact problems, this paper has compared two deep learning approaches to verify their performance experimentally to solve the problems. One of the approaches is a deep autoencoder technique, and another is a deep convolutional neural network (CNN). For those results in the performance of peak signal-to-noise and root mean square error, this paper shows that deep autoencoder method has more advantages than deep CNN approach.

• Restorative Dentistry and Endodontics
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• 제48권2호
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• pp.16.1-16.11
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• 2023

Objectives: The aim of this study was to evaluate the influence of peak kilovoltage (kVp) and a metal artifact reduction (MAR) tool on image quality and the diagnosis of vertical root fracture (VRF) in cone-beam computed tomography (CBCT). Materials and Methods: Twenty single-rooted human teeth filled with an intracanal metal post were divided into 2 groups: control (n = 10) and VRF (n = 10). Each tooth was placed into the socket of a dry mandible, and CBCT scans were acquired using a Picasso Trio varying the kVp (70, 80, 90, or 99), and the use of MAR (with or without). The examinations were assessed by 5 examiners for the diagnosis of VRF using a 5-point scale. A subjective evaluation of the expression of artifacts was done by comparing random axial images of the studied protocols. The results of the diagnoses were analyzed using 2-way analysis of variance and the Tukey post hoc test, the subjective evaluations were compared using the Friedman test, and intra-examiner reproducibility was evaluated using the weighted kappa test (α = 5%). Results: The kVp and MAR did not influence the diagnosis of VRF (p > 0.05). According to the subjective classification, the 99 kVp protocol with MAR demonstrated the least expression of artifacts, while the 70 kVp protocol without MAR led to the most artifacts. Conclusions: Protocols with higher kVp combined with MAR improved the image quality of CBCT examinations. However, those factors did not lead to an improvement in the diagnosis of VRF.

• Imaging Science in Dentistry
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• 제47권2호
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• pp.117-122
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• 2017

Purpose: The aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement. Materials and Methods: Thirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient(ICC) was used to assess intraobserver reliability. Results: The root surface area measurements ($230.11{\pm}41.97mm^2$) obtained using CBCT were slightly greater than those ($229.31{\pm}42.46mm^2$) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT. Conclusion: This study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth.

• Restorative Dentistry and Endodontics
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• 제38권1호
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• pp.2-10
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• 2013

A common failure in endodontic treatment of the permanent maxillary first molars is likely to be caused by an inability to locate, clean, and obturate the second mesiobuccal (MB) canals. Because of the importance of knowledge on these additional canals, there have been numerous studies which investigated the maxillary first molar MB root canal morphology using in vivo and laboratory methods. In this article, the protocols, advantages and disadvantages of various methodologies for in-depth study of maxillary first molar MB root canal morphology were discussed. Furthermore, newly identified configuration types for the establishment of new classification system were suggested based on two image reformatting techniques of micro-computed tomography, which can be useful as a further 'Gold Standard' method for in-depth morphological study of complex root canal systems.