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Competitive relation of wrinkling and dewetting at liquid crystal polymer flim
송성은,유필진 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Liquid crystal films coated on substrates undergo dewetting when adhesion force between polymer film and substrate is lower than gas-polymer surface energy. Generally, the dewetting phenomenon occurs in thin film layer less than 100nm. When thick polymer films become thinning partially, however, also generate dewetting phenomenon. When wrinkling is occurred at polymer films, the wrinkles have wavy form, so that cause partial height change. we can observe the unique patterns which co-exist wrinkling and dewetting are made because of those mutual competitive relation. In this study, we explored the wavelength transition in wrinkling and dewetting through thickness change in Liquid Crystal Polymer(LCP) film. Furthermore, as the directionality of the pattern can be tailored by the structural ordering of LCP molecules in the rubbing process of substrate we show anisotropic wrinkle patterns.
송성은,서보경,이안,구본경,김희영,조규란,정환훈,이승화,황규원 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.6
Objective: To compare between the American College of Radiology (ACR) accreditation phantom and digital mammography accreditation phantom in assessing the image quality in full-field digital mammography (FFDM). Materials and Methods: In each week throughout the 42-week study, we obtained phantom images using both the ACR accreditation phantom and the digital mammography accreditation phantom, and a total of 42 pairs of images were included in this study. We assessed the signal-to-noise ratio (SNR) in each phantom image. A radiologist drew a square-shaped region of interest on the phantom and then the mean value of the SNR and the standard deviation were automatically provided on a monitor. SNR was calculated by an equation, measured mean value of SNR-constant coefficient of FFDM/standard deviation. Two breast radiologists scored visible objects (fibers, specks, and masses) with soft-copy images and calculated the visible rate (number of visible objects/total number of objects). We compared SNR and the visible rate of objects between the two phantoms and calculated the k-coefficient for interobserver agreement. Results: The SNR of the ACR accreditation phantom ranged from 42.0 to 52.9 (Mean, 47.3 ± 2.79) and that of Digital Phantom ranged from 24.8 to 54.0 (Mean, 44.1 ± 9.93) (p = 0.028). The visible rates of all three types of objects were much higher in the ACR accreditation phantom than those in the digital mammography accreditation phantom (p < 0.05). Interobserver agreement for visible rates of objects on phantom images was fair to moderate agreement (k-coefficients: 0.34-0.57). Conclusion: The ACR accreditation phantom is superior to the digital mammography accreditation phantom in terms of SNR and visibility of phantom objects. Thus, ACR accreditation phantom appears to be satisfactory for assessing the image quality in FFDM. Objective: To compare between the American College of Radiology (ACR) accreditation phantom and digital mammography accreditation phantom in assessing the image quality in full-field digital mammography (FFDM). Materials and Methods: In each week throughout the 42-week study, we obtained phantom images using both the ACR accreditation phantom and the digital mammography accreditation phantom, and a total of 42 pairs of images were included in this study. We assessed the signal-to-noise ratio (SNR) in each phantom image. A radiologist drew a square-shaped region of interest on the phantom and then the mean value of the SNR and the standard deviation were automatically provided on a monitor. SNR was calculated by an equation, measured mean value of SNR-constant coefficient of FFDM/standard deviation. Two breast radiologists scored visible objects (fibers, specks, and masses) with soft-copy images and calculated the visible rate (number of visible objects/total number of objects). We compared SNR and the visible rate of objects between the two phantoms and calculated the k-coefficient for interobserver agreement. Results: The SNR of the ACR accreditation phantom ranged from 42.0 to 52.9 (Mean, 47.3 ± 2.79) and that of Digital Phantom ranged from 24.8 to 54.0 (Mean, 44.1 ± 9.93) (p = 0.028). The visible rates of all three types of objects were much higher in the ACR accreditation phantom than those in the digital mammography accreditation phantom (p < 0.05). Interobserver agreement for visible rates of objects on phantom images was fair to moderate agreement (k-coefficients: 0.34-0.57). Conclusion: The ACR accreditation phantom is superior to the digital mammography accreditation phantom in terms of SNR and visibility of phantom objects. Thus, ACR accreditation phantom appears to be satisfactory for assessing the image quality in FFDM.
송성은,조규란,서보경,우옥희,정승필,성득제 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.3
Objective: To investigate the correlation of kinetic features of breast cancers on computer-aided diagnosis (CAD) of preoperative 3T magnetic resonance imaging (MRI) data and clinical-pathologic factors in breast cancer patients. Materials and Methods: Between July 2016 and March 2017, 85 patients (mean age, 54 years; age range, 35–81 years) with invasive breast cancers (mean, 1.8 cm; range, 0.8-4.8 cm) who had undergone MRI and surgery were retrospectively enrolled. All magnetic resonance images were processed using CAD, and kinetic features of tumors were acquired. The relationships between kinetic features and clinical-pathologic factors were assessed using Spearman correlation test and binary logistic regression analysis. Results: Peak enhancement and angio-volume were significantly correlated with histologic grade, Ki-67 index, and tumor size: r = 0.355 (p = 0.001), r = 0.330 (p = 0.002), and r = 0.231 (p = 0.033) for peak enhancement, r = 0.410 (p = 0.005), r = 0.341 (p < 0.001), and r = 0.505 (p < 0.001) for angio-volume. Delayed-plateau component was correlated with Ki-67 (r = 0.255 [p = 0.019]). In regression analysis, higher peak enhancement was associated with higher histologic grade (odds ratio [OR] = 1.004; 95% confidence interval [CI]: 1.001–1.008; p = 0.024), and higher delayed-plateau component and angio-volume were associated with higher Ki-67 (OR = 1.051; 95% CI: 1.011–1.094; p = 0.013 for delayed-plateau component, OR = 1.178; 95% CI: 1.023–1.356; p = 0.023 for angio-volume). Conclusion: Of the CAD-assessed kinetic features, higher peak enhancement may correlate with higher histologic grade, and higher delayed-plateau component and angio-volume correlate with higher Ki-67 index. These results support the clinical application of kinetic features in prognosis assessment.
Competitive concurrence of surface dewetting and wrinkling of liquid crystalline network films
송성은,최관현,유필진 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
In this study, we propose polymeric thin films of liquid crystalline (LC) mesogens prepared on a non-wettable Si substrate and apply a treatment of plasma irradiation to form a thin polymerized layer at the surface. The resulting compressive stress generated in the surface region drives the formation of wrinkles, while at the same time, dipolar attraction between LC molecules induces competitive cohesive dewetting. Intriguing surface structures were obtained whereby dewettinglike hole arrays are nested inside the randomly propagated wrinkles. The structural features are readily controlled by the degree of surface cross-linking, hydrophilicity of the substrates, and the LC film thickness.
Controling competition between wrinkling and dewetting on Non-Wettable substrates
송성은,유필진 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
Polymer thin films coated on substrates undergo dewetting when adhesion force between polymer film and substrate is lower than gas-polymer surface energy. Generally, the dewetting phenomenon occurs in thin film layer less than 100nm. When thick polymer films become thinning partially, however, also generate dewetting phenomenon.When wrinkling is occurred at polymer films, the wrinkles have wavy form, so that cause partial height change. we can observe the unique patterns which co-exist wrinkling and dewetting are made because of those mutual competitive relation. In this study, we explored the wavelength transition in wrinkling and dewetting through thickness change in Liquid Crystal Polymer(LCP) film. Furthermore, as the directionality of the pattern can be tailored by the structural ordering of LCP molecules in the rubbing process of substrate we show anisotropic wrinkle patterns.