• Macromolecular Research
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• v.11 no.4
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• pp.236-240
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• 2003

Fabrication of a graded index profile was possible via photochemical reaction of cinnamoyl groups with 350 nm wavelength UV light to form crosslinked structures. Such structural change may induce the change in the refractive index. In order to generate graded index profile in the PMMA polymer optical fiber (POF) with cinnamoyl groups by photochemistry, a methyl methacrylate monomer containing a cinnamoyl functional group in the side chain were prepared. This monomer was then copolymerized with methyl methacrylate with various compositions not only to utilize advantages of poly(methyl methacrylate) but also to overcome the drawbacks of the cinnamate homopolymer. Changes of refractive indices were investigated with various contents of cinnamoyl group and varying irradiation time. Large change in the refractive index (${\Delta}{\approx}0.01$) and its proper profile shape ($g{\approx}2.2$) can be obtained by changing irradiation time.

• Journal of Korean Neurosurgical Society
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• v.49 no.1
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• pp.26-30
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• 2011

Objective: The primary objective of this study was to perform a retrospective evaluation of the radiological and pathological features influencing the formation of peritumoral brain edema (PTBE) in meningiomas. Methods: The magnetic resonance imaging (MRI) and pathology data for 86 patients with meningiomas, who underwent surgery at our institution between September 2003 and March 2009, were examined. We evaluated predictive factors related to peritumoral edema including gender, tumor volume, shape of tumor margin, presence of arachnoid plane, the signal intensity (SI) of the tumor in T2-weighted image (T2WI), the WHO histological classification (GI, GII/GIII) and the Ki-67 antigen labeling index (LI). The edema-tumor volume ratio was calculated as the edema index (EI) and was used to evaluate peritumoral edema. Results: Gender (p=0.809) and pathological finding (p=0.084) were not statistically significantly associated with peritumoral edema by univariate analysis. Tumor volume was not correlated with the volume of peritumoral edema. By univariate analysis, three radiological features, and one pathological finding, were associated with PTBE of statistical significance: shape of tumor margin (p=0.001), presence of arachnoid plane (p=0.001), high SI of tumor in T2WI (p=0.001), and Ki-67 antigen LI (p=0.049). These results suggest that irregular tumor margins, hyperintensity in T2WI, absence of arachnoid plane on the MRI, and high Ki-67 LI can be important predictive factors that influence the formation of peritumoral edema in meningiomas. By multivariate analysis, only SI of the tumor in T2WI was statistically significantly associated with peritumoral edema. Conclusion: Results of this study indicate that irregular tumor margin, hyperintensity in T2WI, absence of arachnoid plane on the MRI, and high Ki-67 LI may be important predictive factors influencing the formation of peritumoral edema in meningiomas.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.109-113
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• 2004

We have manufactured and characterized the fiber-to-Planar Waveguide Coupler for analysis of the photo-induced refractive index change of DM-BTE .(l,2-bis[2,5-dimethylthio-phen-3-yl]-hexafluorocyclopentene) When irradiated with ultraviolet light, the colorless diarylethene(DM-BTE)-crystal turned red while keeping the crystal shape. The red color was bleached by irradiation with visible light(λ＞450 nm). The resonant wavelength was shifted and recovered owing to the refractive index variation of the planar waveguide because of its photo-functional properties on exposure to UV and visible light. The wavelength responses of this switch by UV exposure were measured as 0.057 nm/sec with saturation time of 60 seconds. and when illuminated by visible light, resonance wavelength variations were measured as 0.028 nm/sec, with recovery time of 140 seconds.

• The Journal of Information Systems
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• v.23 no.1
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• pp.161-184
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• 2014

Our study measures the Digital Life Index (DLI) of baby boomers by considering the utilization of digital devices in their everyday life. The study was conducted by implementing the following three-step approach: (1) development of survey questions and data collection; (2) build Digital Life Index (DLI) model and lastly; (3) empirical analysis using the Digital Life Index (DLI). In the first stage in order to develop the survey questions to measure the digital index, two surveys were conducted. For the first preliminary survey, it was done based on the existing literatures which enabled this investigation through FGI analysis involving real professionals. The second survey was conducted by commissioning a specialized external firm. In this survey, a total of 400 data was collected to verify the validity and objectivity of the data sample. The data gathered through the survey questions was used to develop the digital index. Firstly, the appropriate factors were extracted by conducting factor analysis. This factor analysis validates and verifies the factors which are appropriate in measuring Digital Life Index (DLI). The derived factors are broadly divided into five main factors. The first factor describes the possession, purchase and use of digital device (x1). Meanwhile, the second factor describes the digital device's software (x2) and the third factor describes the participation in utilizing digital device (x3). The fourth factor describes the utilization of digital device in human personal relationship (x4) and lastly, the fifth factor describes the effect of digital device in everyday life and work environment (x5). Secondly, the digital index model was developed. The variables to represent the Digital Life Index (DLI) are ${\chi}1t,{\chi}2t,{\chi}3t,{\chi}4t$ and ${\chi}5t$. Furthermore, as experience in using the digital index grows overtime, the growth can be represented by the "S" shape. Based on the results, Digital Life Index(DLI) is distributed with the highest point at 90.3 and the lowest point at 25.9.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.19-28
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• 2014

PURPOSES : This paper evaluates, using LS/DYNA-3D software, the vehicle impact performance of flexible barriers made of steel W-Beam supported by four different types of post configurations. These types include circular post, H-shape post, C-shape post, and square post. METHODS : The post-soil interaction has been investigated according to different impact angles. For this purpose, energy absorption, maximum displacements of post and rail, and occupant risk index of THIV have been compared each other. The three dimensional soil material model, instead of the conventional spring model based on Winkler and p-y curve, has been used to increase the correctness of computational model. RESULTS : It is noted the crash energy absorption has been increased with respect to the increase of impact angle. CONCLUSIONS : In particular, a post with open section(H-shape, C-shape) shows the greater crash energy absorption capability as compared with a post with closed section under the same level of impact conditions.

• Journal of Korean Neurosurgical Society
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• v.52 no.1
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• pp.21-26
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• 2012

Objective : To evaluate a new posterior atlantoaxial fixation technique using a nitinol shape memory loop as a simple method that avoids the risk of vertebral artery or nerve injury. Methods : We retrospectively evaluated 14 patients with atlantoaxial instability who had undergone posterior C1-2 fusion using a nitinol shape memory loop. The success of fusion was determined clinically and radiologically. We reviewed patients' neurologic outcomes, neck disability index (NDI), solid bone fusion on cervical spine films, changes in posterior atlantodental interval (PADI), and surgical complications. Results : Solid bone fusion was documented radiologically in all cases, and PADI increased after surgery (p<0.05). All patients remained neurologically intact and showed improvement in NDI score (p<0.05). There were no surgical complications such as neural tissue or vertebral artery injury or instrument failure in the follow-up period. Conclusion : Posterior C1-2 fixation with a nitinol shape memory loop is a simple, less technically demanding method compared to the conventional technique and may avoid the instrument-related complications of posterior C1-2 screw and rod fixation. We introduce this technique as one of the treatment options for atlantoaxial instability.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.281.1-281.1
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• 2013

Shape control of gold nanocrystal is still one of the most important challenges remaining to achieve geometry dependent properties. Thus far, several strategies have been developed to control the shape of nanoparticles, such as adding capping agents and diverse additives or adjusting the temperature and pH. Here, we used an already established seed-mediated method that allowed us to focus on controlling the growth stage. Cetyltrimethylammonium bromide (CTAB) and ascorbic acid (AA) were used as the ligand and the reducing agent, respectively, without using any additional additives during the growth stage. We investigated how the relative ratio of CTAB and AA concentrations could be a major determinant of nanoparticle shape over a wide concentration range of CTAB and AA. As a result, a morphology diagram was constructed experimentally that covered the growth conditions of rods, cuboctahedra, cubes, and rhombic dodecahedra. The trends in the morphology diagram emphasize the importance of the interplay between CTAB and AA. Furthermore, high-index faceted gold nanocrystal was obtained by two step seeded growth. Already synthesized cubic particles developed into hexoctahedral nanocrystal consisting of 48 identical {321} facets, which indicates that the growth of gold nanocrystal is affected by initial morphology of seed particles. The hexoctahedral gold nanoparticles can be used in catalysis and optical applications which exploiting their unique geometry. Our research can provide useful guidelines for designing various facetted geometries.

• Journal of the Korean Society of Clothing and Textiles
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• v.47 no.3
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• pp.511-530
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• 2023

This study aims to analyze middle-aged men's frontal body shape asymmetry by measuring the left and right body dimensions and angles of 388 middle-aged men aged 40 to 59 using 3D body scan data and comparing the measured values. The study also compares the measured values of width, height, and angle and their relationships using Size Korea's anthropometric measurement and posture index of the New York Posture Rating Scale. The results confirm that the asymmetric shape characteristics of the upper and lower body appear differently. In addition, the asymmetrical characteristics between the upper and lower body differed, indicating that the close parts of the body affect each other. Similar to the difference in the left and right frontal body shapes and the average angle distribution, the asymmetrical upper and lower body characteristics also are found to be dissimilar when the correlations are examined. In contrast, there is no asymmetry in the width, height, and angle considering the age and BMI groups. Finally, the study classifies three body types and identifies their asymmetric characteristics. Overall, this study contributes primary data for further research on pattern production for asymmetric and unique body types and the development of customized apparel products.

• Nutrition Research and Practice
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• v.17 no.6
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• pp.1143-1154
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• 2023

BACKGROUND/OBJECTIVES: Body shape misperception (BSM) is the disagreement between the subjectively perceived body size and body mass index. This study investigated the association between BSM and unhealthy eating behaviors (UEB) among Korean adolescents. SUBJECTS/METHODS: This cross-sectional study used data from the 2019 Korea Youth Risk Behavior Web-based Survey with 55,748 participants. UEB were measured according to the weekly consumption frequency of caffeinated energy drinks, fast food, carbonated beverages, and sugar-sweetened beverages. The covariates included demographic and socioeconomic characteristics and health-related factors. Multiple logistic regression analysis determined the association between BSM and UEB. RESULTS: Among the participants, 37,607 (67.5%) reported UEB. The gap between UEB among those with BSM was the largest between the underestimated and accurately estimated groups. Participants who underestimated their body shape were likelier to engage in UEB (adjusted odds ratio [AOR], 1.18; 95% confidence interval [CI], 1.11-1.25). Both sexes with underestimation of body size showed an association with UEB compared to those with accurate estimations (girls: AOR, 1.19; 95% CI, 1.09-1.30; boys: AOR, 1.16; 95% CI, 1.08-1.26). CONCLUSIONS: Underestimating body shape can provoke UEB among Korean adolescents. The need for appropriate school health interventional programs to prevent underestimating body shape is emphasized to avoid UEB.

• Journal of Fashion Business
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• v.26 no.1
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• pp.30-40
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• 2022

This study aims to provide basic information on the changes in lower body measurements and shapes of women in their 20s for developing better fitting slacks patterns and a more applicable sizing system that can be widely utilized for women of all ages. Factor and cluster analysis were performed on 1,360 women's direct measurement data within the age group from the 5^th (2004) and 7^th (2015) Korean Human Body Measurement Investigation. The factor analysis identified four factors and explained 82.54% of the total variance; Factor 1, horizontal measurements of lower body; Factor 2, vertical lengths of lower body; Factor 3, measurements of leg and hip areas; Factor 4, lengths of hip and crotch areas. The cluster analysis categorized the lower body shapes of each age group into four shapes; Shape 1, a petite lower body with short legs; Shape 2, a long lower body with medium built; Shape 3, an obese abdomen and legs; Shape 4, a short and slim lower body. Shape 4 (36.5%), Shape 2 (31.2%), Shape 1 (27.8%), and Shape 3 (4.5%) were placed in the order of frequency from the highest to lowest among all the age groups. The findings of this study showed gradual changes in the lower body measurements and shapes of women in their 20s and relevant physical features of each age group. They can be utilized for developing women's slacks patterns with better fitting and more comfort.