• Restorative Dentistry and Endodontics
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• 제26권6호
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• pp.492-498
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• 2001

The purpose of this study was to evaluate four different composite resins in vitro for microleakage in Class II box type restorations that have gingival margins apical to the cementoenamel junction. Forty caries free extracted human molars were used in this study. The Class II cavities were prepared 1.0mm below cementoenamel junction with a #701 carbide bur. The teeth were randomly divided into four groups, each group comprising 20 treated cavities according to adhesives and filling materials ; Group 1: Scotchbond Multipurpose/Z 100. Group 2: Ariston Liner/Ariston pHc, Group 3: One Step/Pyramid, Group 4: Prime & Bond NT/SureFil. To simulate the clinical situation during restoration placement, a restoration template was fabricated and composite resin was filled using a three sited light-curing incremental technique. The specimens were stored in the 100% humidity for 7 days prior to thermocycling. The specimens were immersed in 2% methylene blue dye solution for 24 hours and then embeded in transparent acrylic resin and sectioned mesiodistally with a diamond wheel saw. The degree of marginal leakage was scored under the stereomicroscope($\times$20) and the data were analyzed by Kruskal Wallis test and Mann Whitney test. (omitted)

• Restorative Dentistry and Endodontics
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• 제41권2호
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• pp.143-147
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• 2016

The reconstruction of structurally compromised posterior teeth is a rather challenging procedure. The tendency of endodontically treated teeth (ETT) to fracture is considerably higher than vital teeth. Although posts and core build-ups followed by conventional crowns have been generally employed for the purpose of reconstruction, this procedure entails sacrificing a considerable amount of residual sound enamel and dentin. This has drawn the attention of researchers to fibre reinforcement. Fibrereinforced composite (FRC), designed to replace dentin, enables the biomimetic restoration of teeth. Besides improving the strength of the restoration, the incorporation of glass fibres into composite resins leads to favorable fracture patterns because the fibre layer acts as a stress breaker and stops crack propagation. The following case report presents a technique for reinforcing a badly broken-down ETT with biomimetic materials and FRC. The proper utilization of FRC in structurally compromised teeth can be considered to be an economical and practical measure that may obviate the use of extensive prosthetic treatment.

• 펄프종이기술
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• 제39권1호
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• pp.56-63
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• 2007

The purpose of this research was to identify causes of damage of wax-treated volume of "The Annals of the Joseon Dynasty". As one of the efficient restoration methods, analyses of damaged state of reproduced wax-treated paper through tests of degradation of wax-treated paper under an artificial setting were performed, and in particular, differences between lightness and acidity were observed. On the whole, it was confirmed that yellow wax-treated papers were more stable than white wax-treated papers against artificial aging treatment, which is thought to be because the white wax-treated paper was more affected by a variety of substances interacting with paper than yellow wax-treated paper under artificially aged conditions, which were added in the course of refinement and processing operation such as decolorization and deodorization.

• 대한원격탐사학회지
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• 제38권1호
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• pp.33-43
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• 2022

This study presents a method to restore an optical satellite image with distortion and occlusion due to fog, haze, and clouds to one that minimizes degradation factors by referring to the same type of peripheral image. Specifically, the time and cost of re-photographing were reduced by partially occluding a region. To maintain the original image's pixel value as much as possible and to maintain restored and unrestored area continuity, a simulation restoration technique modified with the Cycle Generative Adversarial Network (CycleGAN) method was developed. The accuracy of the simulated image was analyzed by comparing CycleGAN and histogram matching, as well as the pixel value distribution, with the original image. The results show that for Site 1 (out of three sites), the root mean square error and R² of CycleGAN were 169.36 and 0.9917, respectively, showing lower errors than those for histogram matching (170.43 and 0.9896, respectively). Further, comparison of the mean and standard deviation values of images simulated by CycleGAN and histogram matching with the ground truth pixel values confirmed the CycleGAN methodology as being closer to the ground truth value. Even for the histogram distribution of the simulated images, CycleGAN was closer to the ground truth than histogram matching.

• 한국환경복원기술학회지
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• 제25권2호
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• pp.85-92
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• 2022

The amphibian breeding habitat is confirmed by mating call. In some cases, the researcher directly identifies the amphibian individual, but in order to designate the habitat, it is necessary to map the mating call region of the amphibian population. Until now, it has been a popular methodology for researchers to hear mating calls and outline their breeding habitats. To improve this subjective methodology, we developed a technique for mapping mating call regions using Unmanned Aerial Vehicle (UAV). The technology uses a UAV, fitted with a sound recorder to record ground mating calls as it flies over an amphibian habitat. The core technology is to synchronize the recorded sound pressure with the flight log of the UAV and predict the sound pressure in a two-dimensional plane with probability density. For a demonstration study of this technology, artificial mating call was generated by a potable speaker on the ground and recorded by a UAV. Then, the recorded sound data was processed with an algorithm developed by us to map mating calls. As a result of the study, the correlation coefficient between the artificial mating call on the ground and the mating call map measured by the UAV was R=0.77. This correlation coefficient proves that our UAV recording system is sufficiently capable of detecting amphibian mating call regions.

• 한국환경복원기술학회지
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• 제26권2호
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• pp.47-59
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• 2023

This study investigated and analyzed the effects of vegetation on the roadside slopes at the expressway construction sites in order to evaluate the vegetation recovery regarding soil type and revegetation technique. We selected two study sites with an area of 1,000 m² located in the construction sites of the Korea Expressway Corporation, named Hwado-Yangpyeong Expressway Section 3 and Saemangeum-Jeonju Expressway Section 7. The revegetation was monitored in three plot groups (earth, soft rock, and hard rock slopes), and scored based on the guideline of the Ministry of Land, Transport and Maritime Affairs. The revegatation was generally lower in the Hwado-Yangpyeong site than that of the Saemangeum-Jeonju site. The field monitoring indicated that the revegetation varied with slope aspect and environmental characteristics between plots. the Saemangeum-Jeonju site showed a high overall evaluation score, but there was a slight difference in the score for each plot. This seems to be due to the differences in geographical conditions, construction methods, and site environment between two sites. This study can provide basic information to understand the short-term effects of revegetation techniques in the roadside slopes.

• 한국IT서비스학회지
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• 제22권5호
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• pp.87-98
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• 2023

Traditionally, tooth restoration has been carried out by replicating teeth using plaster-based materials. However, recent technological advances have simplified the production process through the introduction of computer-aided design(CAD) systems. Nevertheless, dental restoration varies among individuals, and the skill level of dental technicians significantly influences the accuracy of the manufacturing process. To address this challenge, this paper proposes an approach to designing personalized tooth restorations using Generative Adversarial Network(GAN), a widely adopted technique in computer vision. The primary objective of this model is to create customized dental prosthesis for each patient by utilizing 3D data of the specific teeth to be treated and their corresponding opposite tooth. To achieve this, the 3D dental data is converted into a depth map format and used as input data for the GAN model. The proposed model leverages the network architecture of Pixel2Style2Pixel, which has demonstrated superior performance compared to existing models for image conversion and dental prosthesis generation. Furthermore, this approach holds promising potential for future advancements in dental and implant production.

• 구강회복응용과학지
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• 제33권2호
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• pp.63-70
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• 2017

임상적으로 고정성보철물의 적합도는 성공적인 수복을 위해 필수적인 요소이다. 보철물의 적합도는 크게 변연적합도와 내면적합도로 분류되며, 이를 평가하기 위한 방법으로는 현미경 변연 측정법, 절단면 측정법, 실리콘 복제법, 3차원 스캔데이터 중첩법, 무게 측정법, 마이크로 CT 측정법 등 다양한 방법들이 소개되고 있다. 이에 본 연구에서는 기존의 문헌들을 바탕으로 각 방법들의 장, 단점을 비교분석함으로써 디지털환경에서 보다 편리하고 정확한 측정법을 제시하고자 한다.

• Journal of Communications and Networks
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• 제12권2호
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• pp.168-173
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• 2010

Error concealment techniques are significant due to the growing interest in imagery transmission over error-prone channels. This paper presents a spatial error concealment technique for losslessly compressed images using least significant bit (LSB)-based data hiding to reconstruct a close approximation after the loss of image blocks during image transmission. Before transmission, block description information (BDI) is generated by applying quantization following discrete wavelet transform. This is then embedded into the LSB plane of the original image itself at the encoder. At the decoder, this BDI is used to conceal blocks that may have been dropped during the transmission. Although the original image is modified slightly by the message embedding process, no perceptible artifacts are introduced and the visual quality is sufficient for analysis and diagnosis. In comparisons with previous methods at various loss rates, the proposed technique is shown to be promising due to its good performance in the case of a loss of isolated and continuous blocks.

• Investigative Magnetic Resonance Imaging
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• 제19권1호
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• pp.19-30
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• 2015

Purpose: A new compressed sensing technique by iterative truncation of small transformed coefficients (ITSC) is proposed for fast cardiac CINE MRI. Materials and Methods: The proposed reconstruction is composed of two processes: truncation of the small transformed coefficients in the r-f domain, and restoration of the measured data in the k-t domain. The two processes are sequentially applied iteratively until the reconstructed images converge, with the assumption that the cardiac CINE images are inherently sparse in the r-f domain. A novel sampling strategy to reduce the normalized mean square error of the reconstructed images is proposed. Results: The technique shows the least normalized mean square error among the four methods under comparison (zero filling, view sharing, k-t FOCUSS, and ITSC). Application of ITSC for multi-slice cardiac CINE imaging was tested with the number of slices of 2 to 8 in a single breath-hold, to demonstrate the clinical usefulness of the technique. Conclusion: Reconstructed images with the compression factors of 3-4 appear very close to the images without compression. Furthermore the proposed algorithm is computationally efficient and is stable without using matrix inversion during the reconstruction.