• Investigative Magnetic Resonance Imaging
• /
• v.25 no.2
• /
• pp.118-128
• /
• 2021

Purpose: To investigate the value of MR textural analysis, including use of diffusion-weighted imaging (DWI) to differentiate malignant from benign soft-tissue tumors on 3T MRI. Materials and Methods: We enrolled 69 patients (25 men, 44 women, ages 18 to 84 years) with pathologically confirmed soft-tissue tumors (29 benign, 40 malignant) who underwent pre-treatment 3T-MRI. We calculated MR texture, including mean, standard deviation (SD), skewness, kurtosis, mean of positive pixels (MPP), and entropy, according to different spatial-scale factors (SSF, 0, 2, 4, 6) on axial T1- and T2-weighted images (T1WI, T2WI), contrast-enhanced T1WI (CE-T1WI), high b-value DWI (800 sec/mm²), and apparent diffusion coefficient (ADC) map. We used the Mann-Whitney U test, logistic regression, and area under the receiver operating characteristic curve (AUC) for statistical analysis. Results: Malignant soft-tissue tumors had significantly lower mean values of DWI, ADC, T2WI and CE-T1WI, MPP of ADC, and CE-T1WI, but significantly higher kurtosis of DWI, T1WI, and CE-T1WI, and entropy of DWI, ADC, and T2WI than did benign tumors (P < 0.050). In multivariate logistic regression, the mean ADC value (SSF, 6) and kurtosis of CE-T1WI (SSF, 4) were independently associated with malignancy (P ≤ 0.009). A multivariate model of MR features worked well for diagnosis of malignant soft-tissue tumors (AUC, 0.909). Conclusion: Accurate diagnosis could be obtained using MR textural analysis with DWI and CE-T1WI in differentiating benign from malignant soft-tissue tumors.

• Journal of Korean Neurosurgical Society
• /
• v.64 no.3
• /
• pp.418-426
• /
• 2021

Objective : A role of diffusion-weighted imaging (DWI) in the diagnosis of cerebral venous thrombosis (CVT) is not well-understood. This study evaluates the effectiveness of DWI in the diagnosis of CVT. Methods : Literature search was conducted in electronic databases for the identification of studies which reported the outcomes of patients subjected to DWI for CVT diagnosis. Random-effects meta-analyses were performed to achieve overall estimates of important diagnostic efficiency indices including hyperintense signal rate, the sensitivity and specificity of DWI in diagnosing CVT, and the apparent diffusion coefficient (ADC) of DWI signal areas and surrounding tissue. Results : Nineteen studies (443 patients with 856 CVTs; age 40 years [95% confidence interval (CI), 33 to 43]; 28% males [95% CI, 18 to 38]; symptom onset to DWI time 4.6 days [95% CI, 2.3 to 6.9]) were included. Hyperintense signals on DWI were detected in 40% (95% CI, 26 to 55) of the cases. The sensitivity of DWI for detecting CVT was 22% (95% CI, 11 to 34) but specificity was 98% (95% CI, 95 to 100). ADC values were quite heterogenous in DWI signal areas. However, generally the ADC values were lower in DWI signal areas than in surrounding normal areas (mean difference-0.33×10-3 ㎟/s [95% CI, -0.44 to -0.23]; p<0.00001). Conclusion : DWI has a low sensitivity in detecting CVT and thus has a high risk of missing many CVT cases. However, because of its high specificity, it may have supporting and exploratory roles in CVT diagnosis.

• Korean Journal of Radiology
• /
• v.22 no.7
• /
• pp.1142-1151
• /
• 2021

Objective: To evaluate microstructural damage in high myopia (HM) patients using 3T diffusion kurtosis imaging (DKI). Materials and Methods: This prospective study included 30 HM patients and 33 age- and sex-matched healthy controls (HCs) with DKI. Kurtosis parameters including kurtosis fractional anisotropy (FA), mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK) as well as diffusion metrics including FA, mean diffusivity, axial diffusivity (AD), and radial diffusivity derived from DKI were obtained. Group differences in these metrics were compared using tract-based spatial statistics. Partial correlation analysis was used to evaluate correlations between microstructural changes and disease duration. Results: Compared to HCs, HM patients showed significantly reduced AK, RK, MK, and FA and significantly increased AD, predominately in the bilateral corticospinal tract, right inferior longitudinal fasciculus, superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and left thalamus (all p < 0.05, threshold-free cluster enhancement corrected). In addition, DKI-derived kurtosis parameters (AK, RK, and MK) had negative correlations (r = -0.448 to -0.376, all p < 0.05) and diffusion parameter (AD) had positive correlations (r = 0.372 to 0.409, all p < 0.05) with disease duration. Conclusion: HM patients showed microstructural alterations in the brain regions responsible for motor conduction and vision-related functions. DKI is useful for detecting white matter abnormalities in HM patients, which might be helpful for exploring and monitoring the pathogenesis of the disease.

• Perspectives in Nursing Science
• /
• v.11 no.1
• /
• pp.30-38
• /
• 2014

Purpose: In recent years, many attempts have been made to examine the effects of forest therapy on health and to develop related policies. This study aimed to explore the current status of health promotion programs using forests provided by public health centers and to identify program diffusion strategies employed within different communities. Methods: For this descriptive study, we analyzed the 5th regional public health care program plans and explored the perceptions of health care workers attached with the programs using open-ended questionnaires and a focus group interview. Results: This study confirmed the necessity for health promotion programs using forests, as well as administrative and educational demands for such programs. The target population of the programs ranged from individuals with specific diseases to healthy local residents. In addition, the programs covered a wide range of topics, including disease management and health promotion strategies. However, the number of well-structured regional specialized programs remained limited. Collaboration among local governments, schools, and public health centers was found to be ineffective. Conclusion: To further disseminate health promotion programs using forests, the central government will need to develop well-structured programs, provide funding and resources to support local governments, and focus on raising public awareness of the health benefits of forest therapy.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.4
• /
• pp.759-767
• /
• 2017

Lactophoricin (LPcin), which is a part of proteose peptone isolated from bovine milk, is a cationic amphipathic ${\alpha}-helical$ antimicrobial peptide. Its truncated variants and mutated analogs were designed and their antimicrobial activities were evaluated by using various assays, like broth dilution methods and disk diffusion methods as well as hemolysis assay. Three analogs, LPcin-C8 (LPcin-YK1), LPcin-T2&6W (LPcin-YK2), and LPcin-T2&6W-C8 (LPcin-YK3), which showed better antibiotic activities than LPcin, were selected. Their secondary structures were also characterized by using CD spectropolarimetry. These three analogs of LPcin could be used as an alternative source of powerful antibacterial agents.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.345-345
• /
• 2006

It is well known that poly(glutamate)s with long n-alkyl side chains form thermotropic liquid crystalline state by melting of the side-chain crystallites and also poly(glutamate)s such as poly(${\gamma}-benzyl\;L-glutamate$ )(PBLG), poly(${\gamma}-n-alkyl\;L-glutamate$), etc. in solvent form the isotropic, biphasic and liquid crystalline phases which contains cholesteric and columnar liquid crystalline forms depending on the polypeptide concentration. Although there is no diffusion study for PBLG in liquid crystalline state, because it is difficult to observed $^{1}H$ spectrum of PBLG in liquid crystalline state for its very short $^{1}H\;T_{2}$. In this study, the diffusional behavior of rodlike PBLG in concentrated solution is successfully elucidated as studied by the field-gradient $^{1}H$ NMR methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.578-581
• /
• 1999

Dot pattern print methods composed of a diffusion film and two prism sheets, have been generally used for backlighting systems of LCDs. However, this methods require complex structures and show high power consumption and optical loss. To improve these disadvantages of conventional backlight units, light guides using highly scattering optical transmissions (HSOT) polymer as scatters, have been introduced. In this study we analyzed multiple scattering effect in light guide by means of Monte carlo simulation based on Mie scattering theory and ray tracing method. As a result it was revealed that scattering intensity depends on the size of scatters. On the other hands, it was shown that scattering efficiency depends on the wavelength of fluorescent lamp as well as the size of scatters.

• Communications of the Korean Mathematical Society
• /
• v.36 no.1
• /
• pp.51-62
• /
• 2021

Variational method has played an important role in solving problems of uniqueness and existence of the nonlinear works as well as analysis. It will also be extremely useful for researchers in all branches of natural sciences and engineers working with non-linear equations economy, optimization, game theory and medicine. Recently, the existence of infinitely many weak solutions for some non-local problems of Kirchhoff type with Dirichlet boundary condition are studied [14]. Here, a suitable method is presented to treat the elliptic partial derivative equations, especially (p(x), q(x))-Laplacian-like systems. This kind of equations are used in the study of fluid flow, diffusive transport akin to diffusion, rheology, probability, electrical networks, etc. Here, the existence of infinitely many weak solutions for some boundary value problems involving the (p(x), q(x))-Laplacian-like operators is proved. The method is based on variational methods and critical point theory.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2007.11a
• /
• pp.190-194
• /
• 2007

In most countries, mobile subscribers are already experiencing 3G-like services. At the moment of launching 3G services, lots of studies showed estimates of the number of subscribers for 3G services, using long-term demand curves, econometric methods or survey methodologies. Those studies mainly focused on the potential number of subscribers and the point of rapid growth rather than precise estimates for the services. Even though we've already experienced parts of 3G services, full length of 3G services are expecting in near future. Therefore, now we need to have more accurate estimates for 3G services. While we thought that 3G services were moved from 2G, in real place 3G services are being evolved from 2G services. In the process of evolving, regulators' policy affects service demand and diffusion significantly. For the more accurate estimates, we need to consider policy issues which influence service diffusion practically in real place. This study aims to present a model which shows better estimates for 3G services with consideration on policy issues, such as numbering issues, price regulation, and competition policy. The consideration can provide more accurate estimates for 3G services with service providers. The methodology could help academicians In forecasting of similar telecommunications services as well.

• The Journal of the Korea Contents Association
• /
• v.7 no.10
• /
• pp.202-210
• /
• 2007

Factor analysis, an important research method, has been conducted as a pre-analysis of empirical researches. Sometimes, the researchers expect more information than factor analysis' limitation as well. Therefore, I suggest a method to overcome this problem. This study presents a combined research method which allow to solve the limitation of the factor analysis in social science. The combined research method consist of factor analysis, AHP(analytic hierarchy process) analysis, diffusion theory and system dynamics, which is able to explain causalities.