• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.9
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• pp.789-795
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• 2014

In this study, the distribution characteristics of diffusers with various shapes that are installed in an open-type thermal storage system are numerically investigated. Four diffusers are designed to distribute a working fluid evenly through the holes on bifurcated pipes. Three-dimensional steady simulations of incompressible laminar flow are conducted using commercial software (ANSYS-FLUENT). The simulation results show that both the bidirectional header-type diffuser and the H-type diffuser distribute the working fluid evenly whereas both the unidirectional and the bidirectional diffusers distribute the working fluid unevenly. The results also show that the H-type diffuser requires a higher head of pump than the bidirectional header-type diffuser. Therefore, the bidirectional header-type diffuser is recommended for use because it enables even distribution of the working fluid and requires a low head of pump.

• Korean Journal of Head & Neck Oncology
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• v.21 no.2
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• pp.190-195
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• 2005

Background and Objectives: Fibula is the flap of choice for reconstruction of wide mandible defects after tumor ablation surgery. In mandible reconstruction, restoring the mandible frame to provide mandibular contour and dental arch while restoring masticatory function are important. Even though vascularized fibula can be osteotomized freely, proper design and flap insetting is not easy because of its three dimensional structure and difference in design according to the defect sites. We reviewed patients who underwent mandible reconstruction with fibular flaps according to the defect sites and suggest proper modification methods of fibular flap according to the various defects sites after tumor ablation surgery. Materials and Methods: Twelve consecutive mandible reconstruction with fibular free flaps were performed for defects after tumor ablation surgery. Patients were classified into 4 groups according to the type of mandibular defect(Group 1 : defect on central segment including symphysis, Group 2 : defect on lateral segment(with or without central segment) confined to body, Group 3 : defect on body and ascending ramus that does not include the condyle, Group 4 : defect including the condyle). Results: We suggest different modification methods of fibular free flap for each patient group. Group 1, 3 ; contour by using multiple closing wedge osteotomy. Group 2 ; single or double barrel reconstruction without wedge osteotomy. Group 4 ; contour using single or multiple wedge osteotomy and condylar reconstruction with costochondral graft. Conclusion: Fibular free flaps can be contoured to any desired shape after multiple osteotomies to restore various mandibular defects. It is a reliable and versatile method for reconstruction of mandibular defects after tumor ablation surgery.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.287-298
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• 1989

A numerical work was performed to study the flow behaviors of the open channel type flow with its geometric boundary conditions being similar to that of the Multi-Stage-Flash evaporator with and without a baffle. For the analysis, two-dimensional steady turbulent flow was assumed and the widely known k-.epsilon. turbulence model was usded. SIMPLE algorithm and the power difference scheme were used for the numerical approach. Numerical results generally agree with the previous experimental results though there are some uncertainties at far downstream and near the free surface due to the three dimensionality of the flow and surface waves. Without a baffle, the flow has basically the shape of the submerged plane wall jet with its upper boundary at downstream being sharply curved toward the free surface. For the flow with a baffle, recirculation flow patterns are observed at the upper inlet portion and at the backside of the baffle. For the case without a baffle, it was also confirmed that the ratio between the liquid level and the gate opening height is the most important parameter to determine the flow behavior.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.69-77
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• 2020

PURPOSE: The aim of this study was to measure changes in spine inclination and thoracolumbar structure and morphology according to upper-extremity movements with and without resistance in order to evaluate the spine stability in workers. METHODS: Forty-eight middle-aged male workers (mean age, 40.48 ± 6.27 years) participated in this study. Using the spine analysis system, changes in the inclination of the spine and structure as well as shape of the thoracolumbar spine were measured. For posture measurement, the postures of standing, lifting the right and left arms (shoulder joint 90° flexion), and lifting with both arms were measured in random order. In addition, variables were measured using a resistance of 3 kg for each posture. The statistical significance level was set at α = .05 for all variables. RESULTS: There were statistically significant differences between the front and back inclinations of the spine, kyphotic curve of the thoracic spine, lordotic curve of the lumbar spine, rotation changes in the thoracolumbar spine, and rotation changes in the T4 vertebra (p < .05). However, there was no significant difference in the left and right tilts of the spine. In the post-hoc analysis, rotation changes in the T4 vertebra showed a significant difference in posture when resistance was applied to the left and right sides CONCLUSION: Causes of musculoskeletal diseases include excessive thoracic spine rotation, torsion, and hyperlordosis of the lumbar spine. Therefore, it is necessary to improve the working environment in order to ensure a healthy posture and prevent musculoskeletal diseases that can reduce the ability to carry various and/or excessive loads.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.539-547
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• 2002

The study proposed the initial equilibrium state analysis method that considers axial deformation, in order to accurately determine the initial shape of a cable-stayed bridge. Sepecifically, the proposed method adopted the successive iteration method. In order to evaluate appropriate initial cable force introduced in the initial equilibrium state analysis, parametric studies were performed and a useful linear analysis method proposed. The geometrically nonlinear static behaviors of cable-stayed bridges were considered, using three-dimensional frame element and elastic catenary cable element. The usefulness and applicability of the analytic method proposed in this study were demonstrated using numerical examples, including a real cable-stayed bridge. The algorithm, is applicable in cases wherein axial deformation is not adopted in the fabrication camber, or final cable force is adjusted to eliminate construction and fabrication errors occurring during construction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.11
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• pp.999-1007
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• 2013

The present work reports numerical results of the pressure drop and heat transfer characteristics of pipes with various shapes such as circular, elliptical, circumferential wavy and twisted using a three-dimensional simulation. Numerical simulations are calculated for laminar to turbulent flows. The fully developed flow in pipes was modeled using steady incompressible Reynolds-averaged Navier-Stokes (RANS) equations. The friction and Colburn factor of each pipe are compared with those of a circular tube. The overall flow and heat transfer calculations are evaluated by the volume and area goodness factor. Finally, the objective of the investigation is to find a pipe shape that decreases the pressure loss and increases the heat transfer coefficient.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.99-106
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• 2013

DME (Di-Methyl Ether) is synthetic product that is produced through dehydration of methanol or a direct synthesis from syngas. And it is able to save fossil fuel and reduce pollutants of emission such as PM and $CO_2$. In spite of its advantages it is difficult to design DME fuelled engine system because DME fuel may cause to severely generate cavitation and corrosion in fuel delivery system due to physical properties of DME. Therefore, in this study three-dimensional internal flow characteristics with consideration of cavitation were predicted in the DME injector using diesel and DME fuel. Moving grid technique was employed to describe needle motion and 1-D hydraulic simulation of injector was also simulated to obtain transient needle motion profiles. The results of simulation show that cavitations was generated at the inlet of nozzle near high velocity region both diesel and DME. And mass flow rate of DME is reduced by 4.73% compared to that of diesel at maximum valve lift because cavitation region of DME is much more larger. To increase flow rate of DME injector, internal flow simulation has been conducted to investigate the nozzle hole inner R-cut effect. The flow rates of diesel and DME increase as R-cut increases, and flow coefficient of DME fuel injector was increased by 6.3% on average compared with diesel fuelled injector. Finally, optimum shape of DME injector nozzle is suggested through the comparison of flow coefficient with variation of nozzle hole inner R-cut.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.11
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• pp.1598-1610
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• 2007

The knit design of this study was developed from reconstruction of Gustav Klimt images including gorgeous colors, symbolic lines, patterns and decorations, and the purpose was laid at making of unique, creative costume image with modem sense and adding artistic value on crochet knit wears. As for the contents and method of this study, We analysed formative aspects of Gustav such as line, color and shape Klimt in his art, and reviewed the cases where his works had been employed in modern costume. The conclusions are as follows; First, painting is important motif for contemporary costume design, and according to the individual thinking and expression, can be a major momentum for development of original design. Especially the organic lines and decorative patterns of Gustav Klimt paintings were suitable for rich decorative motif of costume design. Second, the unique colors of Gustav Klimt paintings can, if introduced to costume, allow new color combination. Third, crochet technic, by the texture of material, can present rich expression even with the basic knitting only. The embroidery metallic thread which is the main material for this study, was good for expression of gorgeous and classy image, in spite of the difficulties from its typical luster and embossed feeling. And the mohair, used as decorative motif, allowed more three dimensional expression with its rich voluminous and tangling property. Fourth, in applying Gustav Klimt paintings to costume design, other technics such as knitting, beading, applique, and patchwork helped creation of more unique clothes, presenting possibilities of rich artistic expression.

• Journal of Educational Research in Mathematics
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• v.24 no.2
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• pp.269-283
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• 2014

Recently, 3S Mathematics Education (Storytelling mathematics education, SMART mathematics education, and STEAM mathematics education) is emphasized. Based on recently published report on Storytelling mathematics textbook, we propose executable expression based SMART storytelling mathematics related to the elementary mathematic curriculum on 3D building blocks. We designed letters and expressions to represent three dimensional shape of 3D building blocks, and we compare its characteristics with that of LEGO blocks. We assert that text-based executable expressions not only construct what students want to make but also teachers can read students thinking process and can support educational help based on students needs. We also present linear function, quadratic function, and function variable concepts using executable expressions based on 3D building block as an example of SMART storytelling mathematics. This research was supported by the collaborated creativity mentoring project between Siheung City and college of education at Seoul National University. We hope designed executable expressions can be used for the development of SMART storytelling mathematics education.

• Journal of Fashion Business
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• v.24 no.4
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• pp.130-143
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• 2020

The development of three-dimensional (3D) printing technology is bringing new innovations to various fields such as health care, architecture, and fashion. 3D printing can be manufactured to suit the size of the consumer's body, modify the design to meet their tastes, and produce small quantities of various products. Therefore, 3D printing in the field of fashion has great potential. The purpose of this study was to investigate various application models of 3D printing for fashion design and analyze their characteristics after developing the fashion garment samples. First, the background of 3D printing was reviewed then, fashion designed by a 3D printing application was analyzed. As a result, four types of 3D printing applications were developed: object-attached, linkage, kinematics, and assembly. The object-attached type was the method of printing 3D material as an object in the intended shape and form and was attached to the garment by sewing. The linkage type referred to printing 3D material in small pieces of certain shapes that could be linked. The kinematics type was structures with hinges that could flex to fit the human body. The assembly type referred to developing 3D materials in female and male pieces such as nuts and bolts. By providing the advantages, disadvantages, trial-and-errors, and challenges of the 3D printing fashion design process, this study contributes to the effective applications and possibilities of future design.