• Nuclear Engineering and Technology
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• 제55권2호
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• pp.655-668
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• 2023

In radiography, an antiscatter grid is a well-known device for eliminating unexpected x-ray scatter. We investigate a new stationary grid artifact suppression method based on a nonsubsampled contourlet transform (NSCT) incorporated with Gaussian band-pass filtering. The proposed method has an advantage that extracts the Moiré components while minimizing the loss of image information and apply the prior information of Moiré component positions in multi-decomposition sub-band images. We implemented the proposed algorithm and performed a simulation and an experiment to demonstrate its viability. We did this experiment using an x-ray tube (M-113T, Varian, focal spot size: 0.1 mm), a flat-panel detector (ROSE-M Sensor, Aspenstate, pixel dimension: 3032 × 3800 pixels, pixel size: 0.076 mm), and carbon graphite-interspaced grids (JPI Healthcare, 18 cm × 24 cm, line density: 103 LP/inch and 150 LP/inch, ratio: 5:1, focal distance: 65 cm). Our results indicate that the proposed method successfully suppressed grid artifacts by reducing them without either reducing the spatial resolution or causing negative side effects. Consequently, we anticipate that the proposed method can improve image acquisition in a stationary grid x-ray system as well as in extended x-ray imaging.

• Archives of Plastic Surgery
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• 제51권1호
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• pp.30-35
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• 2024

Background Breast aesthetics evaluation often relies on subjective assessments, leading to the need for objective, automated tools. We developed the Seoul Breast Esthetic Scoring Tool (S-BEST), a photometric analysis software that utilizes a DenseNet-264 deep learning model to automatically evaluate breast landmarks and asymmetry indices. Methods S-BEST was trained on a dataset of frontal breast photographs annotated with 30 specific landmarks, divided into an 80-20 training-validation split. The software requires the distances of sternal notch to nipple or nipple-to-nipple as input and performs image preprocessing steps, including ratio correction and 8-bit normalization. Breast asymmetry indices and centimeter-based measurements are provided as the output. The accuracy of S-BEST was validated using a paired t-test and Bland-Altman plots, comparing its measurements to those obtained from physical examinations of 100 females diagnosed with breast cancer. Results S-BEST demonstrated high accuracy in automatic landmark localization, with most distances showing no statistically significant difference compared with physical measurements. However, the nipple to inframammary fold distance showed a significant bias, with a coefficient of determination ranging from 0.3787 to 0.4234 for the left and right sides, respectively. Conclusion S-BEST provides a fast, reliable, and automated approach for breast aesthetic evaluation based on 2D frontal photographs. While limited by its inability to capture volumetric attributes or multiple viewpoints, it serves as an accessible tool for both clinical and research applications.

• Journal of Periodontal and Implant Science
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• 제35권4호
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• pp.823-837
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• 2005

The purpose of this study was to study the histopathological correlation between the use of platelet-rich plasma and enamel matrix protein used in conjunction with xenograft. compared to a control group with regards to bone regeneration at the grade III furcation area in beagle dogs. Control group was treated with bovine derived bone $powder(Biocera^{(R)})$, and experimental I group was treated with bovine derived bone powder and Platelet-rich plasma and experimental II group was treated with bovine derived bone powder and Enamel matrix $protein(Emdogain^{(R)})$. The regeneration rate of bone formation was observed and compared histopathologically at 2. 4, and 8 weeks after surgery. The results were as follows: 1. In control group and both experimental groups. inflammatory cells were observed but, new bone formation wasn't. 2. In control group, new cementum on the notch was found in 4 weeks, less mature periodontal ligament when compared to that of experimental group was found and cementum formation was great but, regeneration couldn't be seen in 8 weeks. 3. Experimental I group. new bone formation in the area adjacent to alveolar bone and graft material surrounded by more dense connective tissue were found in 4 weeks. New bone formation up to crown portion was found and periodontal ligament was aligned functionally and cementum more mature. 4. Experimental II group, new bone formation was found under the defect area in 4 weeks and new bone formation around graft material in 8 weeks, too, and there were a number of fibroblasts, blood vessels, acellular cementum, which was less mature when compared to that of experimental I group, and dense collagen fiber like which normal periodontal ligament has in periodontal ligament of experimental II group in 8 weeks. 5. As a result of histologic finding, bone formation rate were 18.0${\pm}$7.87%(control group), 34. 05${pm}$7.25%(experimental I group), 19.33 ${pm}$5.15%(experimental II group) in 4 weeks and 21.89${pm}$1.58%(control group), 38.82${pm}$3.2(experimental I group), 37.65${pm}$9.22%(experimental II group) in 8 weeks. 6. Statistically significant ratio of bone formation was observed in experimental I group in 4 weeks and in experimental II group in 8 weeks. When experimental I group was compared to experimental II group, the ratio of bone formation in experimental I group was higher than that in experimental II group in 4 weeks(p<0.05). This results suggest that platelet-rich plasma showed more new bone formation than enamel matrix protein within 4 weeks. And use of enamel matrix protein in the treatment of periodontal bone defects starts to enhance regeneration after 8 weeks in beagle dogs.

• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.225-237
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• 2018

The difficulties of satellite vibration testing are due to the commonly expressed qualification requirements being incompatible with the limited performance of the entire controlled system (satellite + interface + shaker + controller). Two features cause the problem: firstly, the main satellite modes (i.e., the first structural mode and the high and low tank modes) are very weakly damped; secondly, the controller is just too basic to achieve the expected performance in such cases. The combination of these two issues results in oscillations around the notching levels and high amplitude beating immediately after the mode. The beating overshoots are a major risk source because they can result in the test being aborted if the qualification upper limit is exceeded. Although the abort is, in itself, a safety measure protecting the tested satellite, it increases the risk of structural fatigue, firstly because the abort threshold has been already reached, and secondly, because the test must restart at the same close-resonance frequency and remain there until the qualification level is reached and the sweep frequency can continue. The beat minimum relates only to small successive frequency ranges in which the qualification level is not reached. Although they are less problematic because they do not cause an inadvertent test shutdown, such situations inevitably result in waiver requests from the client. A controlled-system analysis indicates an operating principle that cannot provide sufficient stability: the drive calculation (which controls the process) simply multiplies the frequency reference (usually called cola) and a function of the following setpoint, the ratio between the amplitude already reached and the previous setpoint, and the compression factor. This function value changes at each cola interval, but it never takes into account the sensor signal phase. Because of these limitations, we firstly examined whether it was possible to empirically determine, using a series of tests with a very simple dummy, a controller setting process that significantly improves the results. As the attempt failed, we have performed simulations seeking an optimum adjustment by finding the Least Mean Square of the difference between the reference and response signal. The simulations showed a significant improvement during the notch beat and a small reduction in the beat amplitude. However, the small improvement in this process was not useful because it highlighted the need to change the reference at each cola interval, sometimes with instructions almost twice the qualification level. Another uncertainty regarding the consequences of such an approach involves the impact of differences between the estimated model (used in the simulation) and the actual system. As limitations in the current controller were identified in different approaches, we considered the feasibility of a new controller that takes into account an estimated single-input multi-output (SIMO) model. Its parameters were estimated from a very low-level throughput. Against this backdrop, we analyzed the feasibility of an LQG control in cancelling beating, and this article highlights the relevance of such an approach.

• Elastomers and Composites
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• 제46권4호
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• pp.335-342
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• 2011

비산회를 첨가한 폐 PE의 직접적인 재활용 및 용도 개발을 위하여 재생 폴리에틸렌 수지와 순수 HDPE를 기본으로 비산회(fly ash)와 블렌드하여 비산회/재생 PE 복합재료를 치합형 동방향 회전 이축 압출기(fully intermeshing co-rotating twin screw extruder)를 이용하여 각 조성별로 제조하였다. 본 연구에서는 플라스틱 수지(재생 PE, HDPE)와 비산회의 혼합비를 (0~40) wt.%로 하였고 비산회의 함량 변화에 따른 물성을 비교하였다. 세 종류의 PE 모두 비산회 함량이 증가할수록 항복인장강도가 감소하고, 파단신율이 감소한다. 내마모성 시험 결과는 사포 거칠기가 증가할수록 내마모성이 떨어지고 거칠기가 감소할수록 충전제의 함량에 따라 내마모성이 증가한다. Notched Constant Ligament Stress 시험에서는 신재 PE와 재생 PE의 경우 하중의 변화에 따라 파괴 시간이 짧아지는 결과를 나타냈고, 비산회가 혼합된 KRPE 복합체는 신재 PE, 폐 PE 그리고 신재 PE 복합체 및 JRPE 복합체와 비교할 때 상대적인 파괴 시간은 짧게 나타나지만 매설용 구조물에 대한 한국산업표준에서 정하는 20% 노치 깊이, 15%의 하중에서 24시간 이상의 저속 균열저항성을 나타내어 지하매설용 구조체로서 하수 이음관/받침대와 옥외구조물로서 가로수 보호의자와 같은 구조물에 적용할 수 있을 것으로 판단한다.

• 대한치과교정학회지
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• 제27권4호
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• pp.523-538
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• 1997

서울대학교병원 치과 교정과에 내원한 6세 1개월에서 45세 8개월사이(평균 19세 6개월)의 부정교합자 205명(남 67명, 여 138명)을 대상으로 TMD 증상과 기여요인에 관한 설문조사와 Orthopantomogram, 경두개 방사선 사진(transcranial view)의 판독, 교정모형 검사 등을 시행하여 다음과 같은 결론을 얻었다. 1. Helkimo Anamnestic index는 Ai 0 $46.8\%$, Ai I $22.0\%$, Ai II $31.2\%$로 TND의 주관적 증상이 연령에 따라 증가하는 추세(p<0.001)를 보였으며 여성에서 높았다(p<0.05). 2. Orthopantomogram상 하악두의 이상소견은 flattening($4.4\%$)이 가장 많았으며 전체적으로 한가지 이상의 이상소견을 보인 경우는 $8.3\%$였다. 3. 목과 어깨의 동통(p<0.001) 이악물기, 입술을 깨무는 습관(이상 p<0.01). 두통(p<0.05)이 있는 경우 Ai가 높았다. 4. Angle II급에서 Orthopantomogram상 하악두 이상소견의 빈도가 높았고, 상악 대구치의 교모가 있을때 Ai가 높은 경향이 있었다(이상 p<0.05). 그외의 교합 요소는 TMD의 증상과 무관하였다. 5. 하악두 길이(Co'-Inc')와 하악지 길이(Co'-Go')가 짧고 하악두의 비율(Co'-Inc'/Co'-Go')이 낮을때, 그리고 좌우 하악지 길이 (Co'-Go'), 하악두 비율(Co'-Inc'/Co'-Go')이 다를때 Orthopantomogram상 하악두 이상소견이 많았다.

• Animal Bioscience
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• 제36권7호
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• pp.991-1002
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• 2023

Objective: This study aimed to elucidate the underlying gene regions responsible for productive, phenotypic or adaptive traits in different ecological types of Tibetan sheep and the discovery of important genes encoding valuable traits. Methods: We used whole-genome resequencing to explore the genetic relationships, phylogenetic tree, and population genetic structure analysis. In addition, we identified 28 representative Tibetan sheep single-nucleotide polymorphisms (SNPs) and genomic selective sweep regions with different traits in Tibetan sheep by fixation index (Fst) and the nucleotide diversity (θπ) ratio. Results: The genetic relationships analysis showed that each breed partitioned into its own clades and had close genetic relationships. We also identified many potential breed-specific selective sweep regions, including genes associated with hypoxic adaptability (MTOR, TRHDE, PDK1, PTPN9, TMTC2, SOX9, EPAS1, PDGFD, SOCS3, TGFBR3), coat color (MITF, MC1R, ERCC2, TCF25, ITCH, TYR, RALY, KIT), wool traits (COL4A2, ERC2, NOTCH2, ROCK1, FGF5, SOX9), and horn phenotypes (RXFP2). In particular, a horn-related gene, RXFP2, showed the four most significantly associated SNP loci (g. 29481646 A>G, g. 29469024 T>C, g. 29462010 C>T, g. 29461968 C>T) and haplotypes. Conclusion: This finding demonstrates the potential for genetic markers in future molecular breeding programs to improve selection for horn phenotypes. The results will facilitate the understanding of the genetic basis of production and adaptive unique traits in Chinese indigenous Tibetan sheep taxa and offer a reference for the molecular breeding of Tibetan sheep.

• 한국구조물진단유지관리공학회 논문집
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• 제10권3호
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• pp.185-196
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• 2006

파괴인성은 균열의 개시와 전파에 대한 재료 고유의 상수로서 파괴역학에서 가장 중요한 재료상수 중의 하나이다. 콘크리트의 모드 I 파괴인성 측정에 대하여 RILEM 기술 위원회 89-FMT는 2-파라메타 모델에 근거한 3점 휨 시험법을 제시하였다. 그러나 혼합모드에 대한 시험법은 아직까지 표준으로 제안된 방법이 없는 실정이며, 또한 RILEM에서 제안한 3점 휨 시험법은 실험법이 복잡하다. 따라서 본 연구에서는 굵은골재의 최대치수가 각각 20mm, 40mm이고, 동일한 설계기준강도를 가지는 콘크리트로써 다양한 크기의 브라질리언 디스크를 제작하였다. 그리고 브라질리언 디스크의 모드 I 파괴인성을 RILEM 3점 휨 시험결과와 비교하였다. 비교 결과, 굵은골재의 최대치수에 따른 브라질리언 디스크의 적정 크기(두께, 직경) 및 노치 길이 비를 제시하였다. 또한 모드 I 시험으로부터 결정된 치수의 브라질리언 디스크로 혼합모드 시험을 수행한 결과 디스크 시편은 혼합모드 파괴의 연구 및 시험에 유용함을 알 수 있었다. 모드 I 및 혼합모드 시험에서 브라질리언 디스크의 응력확대계수는 유한요소해석(FEA)으로 구하였으며 FEA의 결과를 검증하기 위하여 5개항 근사법(Five terms approximation)에 의한 결과와 비교하였다.

• 대한치과교정학회지
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• 제41권2호
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• pp.87-97
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• 2011

안면비대칭의 원인은 다양하며, 비대칭적 성장은 상악골과 하악골의 길이나 각도로 평가되어지곤 한다. 하지만 하악 과두의 비대칭적인 위치나 형태 또한 비대칭의 표현에 영향을 줄 것으로 생각된다. 따라서 본 연구는 하악 과두가 안면비대칭의 표현형인 이부 편위에 영향을 주는지에 대해 알아보고자 하였다. 50명의 골격성 III급 부정교합자 중 4 mm 이상의 menton point deviation을 보이는 비대칭군 30명, 4 mm 이하의 menton point deviation을 보이며 뚜렷한 안면비대칭이 없는 20명을 대칭군으로 하여, 두개저에 대한 좌우 하악 과두의 근원심적, 전후방적 위치를 평가하고, axial 평면에서 장축을 설정해 하악 과두의 최대 크기와 coronal plane에 대한 각도를 평가하였으며, sigmoid notch 상방 하악 과두의 길이와 부피를 측정하였다. 대칭군은 좌우 하악 과두의 위치, 각도, 크기, 길이, 부피에 있어 통계적인 차이가 없었다. 비대칭군은 이부 편위측과 비편위측으로 나누어볼 때, 이부 편위에 따른 좌우 하악 과두의 위치와 angulation 에서 통계적 차이는 없었으나, 하악 과두의 크기, 길이 및 부피에서는 비편위측 값이 컸고, 이부 편위량이 클수록 좌우 크기, 길이의 차이 및 편위측에 대한 비편위측 하악 과두의 부피비가 컸다. 또한 편위측에 대한 비편위측 하악 과두의 부피비가 이부 편위의 정도를 가장 잘 설명해주는 특성이었다. 이상의 결과를 통해 하악 과두의 비대칭이 안면비대칭의 발현에 영향을 주며, 비편위측 하악 과두가 편위측에 비해 크고 길다는 것을 알 수 있었다.