• Smart Structures and Systems
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• 제23권6호
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• pp.627-639
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• 2019

Passive control may not provide enough damping for a stay cable since the control devices are often restricted to a low location level. In order to enhance control performance of conventional passive dampers, a new type of damper integrated with a rotary electromagnetic damper providing variable damping force and a flywheel serving as an inertial mass, called the rotary electromagnetic inertial mass damper (REIMD), is presented for suppressing the cable vibrations in this paper. The mechanical model of the REIMD is theoretically derived according to generation mechanisms of the damping force and the inertial force, and further validated by performance tests. General dynamic characteristics of an idealized taut cable with a REIMD installed close to the cable end are theoretically investigated, and parametric analysis are then conducted to investigate the effects of inertial mass and damping coefficient on vibration control performance. Finally, vibration control tests on a scaled cable model with a REIMD are performed to further verify mitigation performance through the first two modal additional damping ratios of the cable. Both the theoretical and experimental results show that control performance of the cable with the REIMD are much better than those of conventional passive viscous dampers, which mainly attributes to the increment of the damper displacement due to the inertial mass induced negative stiffness effects of the REIMD. Moreover, it is concluded that both inertial mass and damping coefficient of an optimum REIMD will decrease with the increase of the mode order of the cable, and oversize inertial mass may lead to negative effect on the control performance.

• 한국의상디자인학회지
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• 제21권3호
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• pp.109-119
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• 2019

The purpose of this study is to examine fashion trends and the direction of the four fashion collections by analyzing the design key-words of the four major international fashion collections in 2018. The data of this study was collected by extracting the key-words from Marie Claire Korea in 2018, with the total of the collected data numbering 2,144. The data was analyzed by text mining using the R program and word-cloud, and a co-occurrence network analysis was conducted. The results of this study are as follows: First, the key-words of fashion collection designs in 2018 were fringe and ruffle detail, silk and denim fabric, vivid color, stripe and check pattern, pants suit item, and oversized silhouette, focusing on romanticism and sport. Second, seasonal characteristics of the fashion collections were pastel colors in S/S, primary and vivid colors in F/W. Details were embroidery and cutouts in S/S, patchwork and fringe in F/W. Third, the design trends of the four major fashion collections were presented in the Paris collection: stripes, check patterns, embroidery, lace, tailoring, draping, romanticism, and glamor. In the Milan collection, checks, prints, denim, and minidresses reflected sport and romanticism. The London collection included fringe, ruffles, floral patterns, flower patterns, and romanticism. The New York collections included vivid colors, neon colors, pastel colors, oversize silhouettes, bodysuits, and long dresses.

• The Journal of Advanced Prosthodontics
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• 제15권1호
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• pp.22-32
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• 2023

PURPOSE. Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS. Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS. There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P < .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION. The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

• 한국방사선학회논문지
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• 제12권1호
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• pp.23-30
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• 2018

흉부 단층 합성검사(Chest Digital Tomosynthesis, DTS)시 환자 체형에 따른 0.3 mm 구리 필터의 적용 및 AEC의 감도 변화에 의한 유효선량감소 효과와 폐 결절 검출능력을 평가하여 선량 최적화 조건을 평가하고자 한다. 8개의 인공 결절을 인체 팬텀 폐 영역내에 삽입하고 0.3 mm 구리 필터 적용 유무, 감도 변화에 따라 팬텀의 DTS 영상을 각각 획득하였다. 환자 체형에 따른 비교를 위해 팬텀 사이즈를 세 그룹으로 분류하여 small size에서는 결절이 삽입된 인체 팬텀을 단독으로 사용하였고 Average size에서는 한 개의 PMMA를, Large size에서는 두 개의 PMMA를 인체팬텀 후방에 밀착하여 위치시켰다. 유효선량은 몬테카를로 시뮬레이션을 이용하여 계산 되었고 영상의 화질평가를 위해서 CNR과 SNR 측정을 통한 정량 평가와 인공 결절 검출 수를 통한 검출민감도로 정성평가를 시행하였다. 모든 데이터는 통계학적으로 분석하였다. 유효 선량은 Small size일 때 $26{\mu}Sv$, Average size $70{\mu}Sv$, Large size $133{\mu}Sv$ 감소하였다. 유효선량은 0.3mm 구리 필터의 적용 여부에 따라 유의한 차이가 있었다(p<0.05). 정량적 화질 평가에서는 0.3mmCu필터 사용 시 CNR과 SNR 모두 통계적으로 유의한 차이는 없었다(p>0.05). 또한 정성적 화질평가에서도 결절 검출 민감도는 팬텀 사이즈별 전체 그룹에서 통계적으로 유의한 차이가 없었다(p>0.05). DTS에서 0.3 mmCu필터의 사용은 폐 결절 검출에서 진단적 가치를 유지하면서 환자 피폭선량 감소효과를 얻을 수 있다. 또한 실험에서 Large size 그룹의 경우 유효선량 감소 정도가 두드러진 점으로 보아 실제 체형이 큰 환자의 경우 0.3 mm Cu필터 사용은 더 높은 유효선량 감소 효과를 기대 할 수 있을 것이라 사료된다