• Korean Journal of Construction Engineering and Management
• /
• v.15 no.4
• /
• pp.95-106
• /
• 2014

The outer surfaces of free form buildings contain panels with two-directional curvatures. To construct these panels, complex geometric surfaces should be divided into forms and sizes that can be manufactured and constructed efficiently. Because the bigger the curvatures of these panel, the more expensive the construction costs, these complex curvatures should go through optimal process of reinterpretation to minimize the curved surfaces with complex two-directional curvatures, which is called panel optimization. Small construction and design companies have trouble in calculating even rough estimate and cannot adjust expected construction cost of the panels based on comparison of design alternatives in conjunction with panel optimization process due to lack of knowledge and experience. This study conducts the research that can support designers' cost decision-making in the design stage of the free form buildings with respect to the panel optimization process. A 3D commercial application specialized to modeling free form shapes is used for the purpose.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.6
• /
• pp.1511-1517
• /
• 2008

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. The magneto-rheological fluid damper, which uses such characteristics of the fluid, generates shear force due to the fluid's cohesiveness. The core can be said to determine the magneto-rheological fluid damper's performance. This study uses the finite element analysis to compare the performance of different electromagnetic forces, which are affected by the shapes of the coil, and thus to find the optimum design for the core. In addition, as a step to construct a high-efficient damper, we suggest a type of damper that can control multiple coils and compares the performance of this damper and that of the standard damper by comparing the performance of their electro-magnetic fields.

• Archives of design research
• /
• v.12 no.2
• /
• pp.43-50
• /
• 1999

The purpose of this study is to suggest the standard size of a bench in the park. To obtain the basic shapes and size of a bench in the park, several parks are selected as a sample which is located in 6 major cities in Korea. Those obtained basic data of a bench are compared to standard size of a bench in United State and Japan and then human engineering concepts are applied to determine the optimal standard size. Furthermore the standard size of a bench is suggested in two classifications. One for the adults and the other for the children. This study is limited to a determining the standard size of a bench but in the future study, overall facilities in the park for the human being ha<> to be examined.

• Journal of Korean Dental Science
• /
• v.11 no.2
• /
• pp.62-70
• /
• 2018

Purpose: Bone marrow has long been a source of primary cells. This study was performed to evaluate the effects of age and sex on the cellular viability and expression of stem cell markers of mRNA and on the protein expression of bone marrow stem cells (BMSCs) derived from healthy donors. Materials and Methods: Stem cells were isolated from human bone marrow and plated in culture plates. The shape of the BMSCs was observed under inverted microscope. Quantitative cellular viability was evaluated using a Cell-Counting Kit-8 assay. The expression of stem cell surface markers was tested and a series of quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot was performed to evaluate the expression in each group. Result: The shapes of the cells at 20s, 30s, and 50s were similar to each other. No significant changes in cellular viability were noted among different age groups or sex groups. The BMSCs expressed CD44, CD73, and CD90 surface markers but did not express CD14 and CD34. There were no noticeable differences in CD surface markers among the different age groups. The expressions of CD surface markers were similar between men and women. No significant differences in the secretion of vascular endothelial growth factors (VEGFs) were noted at Day 3 between different age groups. qRT-PCR regarding the expression showed differences between the age groups. However, Western blot analysis showed a decrease in expression but did not reach statistical significance (P>0.05). Conclusion: This study clearly showed no significant differences in shape, cell viability, expression of stem cell surface markers, or secretion of human VEGF among different age groups. However, western blot analysis showed a tendency of age-related decrease which did not reach statistical significance. Collectively, autologous or allogeneic BMSCs should be meticulously applied to obtain optimal results regarding age and sex.

• Journal of Aerospace System Engineering
• /
• v.13 no.1
• /
• pp.29-37
• /
• 2019

The objective of this study was to investigate the influence of the blade shape on the impeller performance, for design optimizing of the high airflow impeller. First, the quantity, angle, and length of blades, which are considered to have a large influence on the impeller performance, were selected as design variables. Then, 27 cases of impeller shapes were selected according to the design of experiment (DOE). To predict the conduct of the blower based on the selected impeller shape, flow analysis was performed using the immersed solid method of ANSYS CFX. In the CFD results, the highest airflow was expected in the impeller having a combination of 50 EA, $6^{\circ}$ and 5 mm. Finally, a blower with the original impeller shape and the optimized impeller shape was fabricated using a 3D printer, and the analysis tendency and experimental tendency were verified through experiments.

• Composites Research
• /
• v.33 no.6
• /
• pp.353-359
• /
• 2020

In this work, a contour-based section analysis method incorporating the use of Bézier curves is attempted for the construction of optimal structural design framework of composite helicopter blades. The suggested section analysis method is able to analyze composite blades with solid cores made of arbitrary materials and geometric shapes. The contour-based section analysis method is integrated into a blade structural optimization framework to confirm the efficiency of the present approach. The numerical simulation result demonstrates that the optimized blade configurations are obtained with a reduction in mass by 52%, compared to the baseline blade. For the structural optimization of composite blades with 19 subsections, it takes about one hour for the successful optimization while satisfying all the design constraints considered in this study, which reveals the efficiency of the present approach.

• Investigative Magnetic Resonance Imaging
• /
• v.25 no.1
• /
• pp.23-34
• /
• 2021

Purpose: Differentiating between glioblastoma and solitary metastasis is very important for the planning of further workup and treatment. We assessed the ability of various morphological parameters using conventional MRI and diffusion-based techniques to distinguish between glioblastomas and solitary metastases in tumoral and peritumoral regions. Materials and Methods: We included 38 patients with solitary brain tumors (21 glioblastomas, 17 solitary metastases). To find out if there were differences in the morphologic parameters of enhancing tumors, we analyzed their shape, margins, and enhancement patterns on postcontrast T1-weighted images. During analyses of peritumoral regions, we assessed the extent of peritumoral non-enhancing lesion on T2- and postcontrast T1-weighted images. We also aimed to detect peritumoral neoplastic cell infiltration by visual assessment of T2-weighted and diffusion-based images, including DWI, ADC maps, and exponential DWI, and evaluated which sequence depicted peritumoral neoplastic cell infiltration most clearly. Results: The shapes, margins, and enhancement patterns of tumors all significantly differentiated glioblastomas from metastases. Glioblastomas had an irregular shape, ill-defined margins, and a heterogeneous enhancement pattern; on the other hand, metastases had an ovoid or round shape, well-defined margins, and homogeneous enhancement. Metastases had significantly more extensive peritumoral T2 high signal intensity than glioblastomas had. In visual assessment of peritumoral neoplastic cell infiltration using T2-weighted and diffusion-based images, all sequences differed significantly between the two groups. Exponential DWI had the highest sensitivity for the diagnosis of both glioblastoma (100%) and metastasis (70.6%). A combination of exponential DWI and ADC maps was optimal for the depiction of peritumoral neoplastic cell infiltration in glioblastoma. Conclusion: In the differentiation of glioblastoma from solitary metastatic lesions, visual morphologic assessment of tumoral and peritumoral regions using conventional MRI and diffusion-based techniques can also offer diagnostic information.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.4
• /
• pp.71-77
• /
• 2021

Several cooling techinques have been studied for protecting gas turbine blades from hot gas. In terms of film-cooling techniques, various shapes of film cooling holes have been studied including fan shaped holes, which are used on gas turbine blades. However, owing to increasing demands on smaller gas turbines, a research on film-cooling holes on thin walls is required. This study was conducted at blowing ratios of 1 and 2, using numerical analysis. Through the numerical analysis, the effect of geometrical parameters on the effectiveness of fan-shaped hole film cooling was studied. Moreover, optimization was performed on three geometrical parameters: metering length, lateral expansion angle and forward expansion angle. As a result, we realized that the optimal fan-shaped holes on each blowing ratio were found to have very similar geometry and cooling performance.

• Journal of The Korean Astronomical Society
• /
• v.55 no.5
• /
• pp.149-172
• /
• 2022

We present a new method which constructs an Hɪ super-profile of a galaxy which is based on profile decomposition analysis. The decomposed velocity profiles of an Hɪ data cube with an optimal number of Gaussian components are co-added after being aligned in velocity with respect to their centroid velocities. This is compared to the previous approach where no prior profile decomposition is made for the velocity profiles being stacked. The S/N improved super-profile is useful for deriving the galaxy's global Hɪ properties like velocity dispersion and mass from observations which do not provide sufficient surface brightness sensitivity for the galaxy. As a practical test, we apply our new method to 64 high-resolution Hɪ data cubes of nearby galaxies in the local Universe which are taken from THINGS and LITTLE THINGS. In addition, we also construct two additional Hɪ super-profiles of the sample galaxies using symmetric and all velocity profiles of the cubes whose centroid velocities are determined from Hermite h3 polynomial fitting, respectively. We find that the Hɪ super-profiles constructed using the new method have narrower cores and broader wings in shape than the other two super-profiles. This is mainly due to the effect of either asymmetric velocity profiles' central velocity bias or the removal of asymmetric velocity profiles in the previous methods on the resulting Hɪ super-profiles. We discuss how the shapes (𝜎_n/𝜎_b, A_n/A_b, and A_n/A_tot) of the new Hɪ super-profiles which are measured from a double Gaussian fit are correlated with star formation rates of the sample galaxies and are compared with those of the other two super-profiles.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5A
• /
• pp.477-486
• /
• 2009

This paper deals with the strongest static arches with the solid regular polygon cross-section. Both span length and volume of arch are always held constant regardless the shape functions of cross-sectional depth of regular polygon. The normal stresses acting on such arches are calculated when both static vertical and horizontal point loads are subjected. By using the calculating results of stresses, the optimal shapes of strongest static arches are obtained, under which the maximum normal stress become to be minimum. For determining the redundant of such indeterminate arches, the least work theorem is adopted. As the numerical results, the configurations, i.e. section ratios, of the strongest static arches are reported in tables and figures. The results of this study can be utilized in the field of the minimum weight design of the arch structures.