• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.875-880
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• 2014

Recently, three-dimensional scaffolds and nanofibers are being developed for bone tissue regeneration. In this study, we fabricated a hybrid scaffold using a nano-micro precision deposition system. The fabrication process involved the application of the solid freeform fabrication (SFF) technology and electrospinning. The hybrid scaffolds were combined using micro scaffolds and nanofibers. The nanofibers were deposited on each layer of the micro scaffolding using the electrospinning process. The micro scaffolds were fabricated using the SFF technology at a temperature of $100^{\circ}C$, pressure of 650 kPa, and scan velocity of 250 mm/s. Nanofiber fabrication was conducted by means of electrospinning using the flow rate, solution concentration, distance from the tip to the collector (TCD), and voltage. The nanofibers were fabricated using a flow rate of 0.1 ml/min, voltage of 5 kV, TCD of 1 mm, and 10 wt% of solution concentration. MG-63 cells were seeded into the hybrid scaffold for the purpose of its evaluation.

• International Journal of CAD/CAM
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• v.5 no.1
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• pp.1-10
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• 2005

A new approach based on vector field clustering for tool path optimization of 5-axis CNC machining is presented in this paper. The strategy of the approach is to produce an efficient tool path with respect to the optimal cutting direction vector field. The optimal cutting direction maximizes the machining strip width. We use the normalized cut clustering technique to partition the vector field into clusters. The spiral and the zigzag patterns are then applied to generate tool path on the clusters. The iso-scallop method is used for calculating the tool path. Finally, our numerical examples and real cutting experiment show that the tool path generated by the proposed method is more efficient than the tool path generated by the traditional iso-parametric method.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.166-173
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• 2006

This study investigates a heavy duty diesel engine with swept vol. 12.6L, 4cycle-OHC type to verify the effects of the performance and exhaust gas emission according to the variable specifications of both swirl ratio and flow coefficient in inlet port, combustion bowl and fuel injection system. To meet the high BMEP and stringent exhaust emission standard, a turbocharger with wastegate and an intercooler were installed in the engine. Helical port, major design parameters for combustion chamber and electronic fuel injection pump with 1,000bar were reviewed and applied. Confirmation tests were also performed to meet the target value, $NO_x$ 5.0g/kWh and PM 0.1g/kWh of Euro3 exhaust emission legislation. The results of this study show that not only is it effective to use a relatively bigger bowl size for controlling rapid burning condition due to the decreased in-bowl swirl, but also to use a concave cam with double injection rates to decrease $NO_x$.

• Korean Journal of Veterinary Research
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• v.49 no.4
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• pp.273-278
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• 2009

Neurofascin, one of the members of L1CAM, has been known to have some important roles during the development of nerve fibers. In order to investigate the role of neurofascin associated with the formation of Schmidt-Lantermann incisure in the sciatic nerve, the localization of neurofascin was studied with electron microscopy, immuno-fluorescence and immuno-electron microscopy. In the electron microscopy, the first formation of Schmidt-Lantermann incisure was checked at postnatal day 6 and the complete form of incisures traversing the whole myelin sheath began to be observed at postnatal day 8. In the immunofluorescence, neurofascin immunoreactive Schmidt-Lantermann incisures were first checked at postnatal day 6 and dramatically increased with aging by postnatal day 56. In the immunoelectron microscopy, neurofascin immunoreactive gold particles at the incisure forming sites were first observed at postnatal day 6 and the number of gold particles was increased as the animal was getting old by postnatal day 56. According to the present study, neurofascin is likely to have some relationships with Schmidt-Lantermann incisure formation.

• Journal of Haehwa Medicine
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• v.14 no.2
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• pp.107-112
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• 2005

Peripheral axons in vertebrate animals can regenerate after nerve injury and accomplish its functional recovery. Numerous studies have revealed that diverse molecular factors are induced during axonal regeneration and their potential roles in axonal regeneration have been studied. Examples is N-CAM, L1, P0, nerve growth factors, GAP-43 and so forth. However, most of the studies on axonal regeneration have been primarily focused on axon fiber regrowth and elucidating molecular factors, and relatively less is known about functional recovery. Also, specific drugs or drug components used in the oriental medicine in relation to nerve fiber regeneration have not been known. And thus, in the present, a study on the effect of Samul-tang components and Samul-tang extracts to regeneration of peripheral axon fiber is underway by immunofluorescence staining. Therefore, this prior application of Samul-tang with documents consideration is reported with a plea for further investigation.

• International Journal of CAD/CAM
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• v.12 no.1
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• pp.20-28
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• 2012

Finite Element Analysis (FEA) is often used to identify local stress/strain concentrations where a component is likely to fail. In order to reduce the degree of strain concentration, component thickness can be increased in those regions, or a stronger material can be used. In short fiber reinforced composite materials, strength and stiffness can be increased through proper fiber alignment. The field-aided microtailoring (FAiMTa) process is one promising method for doing this. FAiMTa uses principles of dielectrophoresis to preferentially align particles or fibers within a matrix. To achieve the preferred fiber orientation, an interdigitated electrode network must be integrated into the mold halves which can be fabricated by additive manufacturing (AM) processes. However, the process of determining the preferred fiber arrangements and electrode locations can be very challenging. This paper presents algorithms to semi-automate the interdigitated electrode design process. The algorithm has been implemented in the Solidworks CAD system and is demonstrated in this paper.

• International Journal of CAD/CAM
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• v.9 no.1
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• pp.61-69
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• 2010

Based on the equivalence principles of physical properties, geometric properties and externally applied forces between a surface and the corresponding curves, we present a fast physics and example based skin deformation method for character animation in this paper. The main idea is to represent the skin surface and its deformations with a group of curves whose computation incurs much less computing overheads than the direct surface-based approach. The geometric and physical properties together with externally applied forces of the curves are determined from those of the surface defined by these curves according to the equivalence principles between the surface and the curves. This ensures the curve-based approach is equivalent to the original problem. A fourth order ordinary differential equation is introduced to describe the deformations of the curves between two example skin shapes which relates geometric and physical properties and externally applied forces to shape changes of the curves. The skin deformation is determined from these deformed curves. Several examples are given in this paper to demonstrate the application of the method.

• International Journal of CAD/CAM
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• v.7 no.1
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• pp.31-40
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• 2007

Reverse engineering of reliefs aims to turn an existing relief superimposed on an underlying surface into a geometric model which may be applied to a different base surface. Steps in this process include segmenting the relief from the background, and describing it as an offset height field relative to the underlying surface. We have previously considered relief segmentation using a geometric snake. Here, we show how to use this initial segmentation to estimate the background surface lying under the relief, which can be used (i) to refine the segmentation and (ii) to express the relief as an offset field. Our approach fits a B-spline surface patch to the measured background data surrounding the relief, while tension terms ensure this background surface smoothly continues underneath the relief where there are no measured background data points to fit. After making an initial estimate of relief offset height everywhere within the patch, we use a support vector machine to refine the segmentation. Tests demonstrate that this approach can accurately model the background surface where it underlies the relief, providing more accurate segmentation, as well as relief height field estimation. In particular, this approach provides significant improvements for relief concavities with narrow mouths and can segment reliefs with small internal holes.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.6
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• pp.1602-1607
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• 2004

3-O-D-galactopyranosylglyceride (GPG; fatty acids R1, R2 = myristic acid 11.62%, palmitic acid 61.90% and oleic acid 26.48%) was isolated from Chrysanthemum coronarium L that has been used for treating renal and cardiovascular diseases as one of vegetables or medicinal drug. However, little was known about the anti-angiogenic activity of GPG. Thus, anti-angiogenic effect of GPG was evaluated in human umbilical vein endothelial cells (HUVECs) in vitro and in vivo. GPG effectively inhibited bFGF-induced migration and invasion of HUVECs in a concentration-dependent manner, whereas it did not inhibit bFGF-induced proliferation and capillary-like tube formation of HUVECs. To examine the mechanism of anti-angiogenic activity of GPG, gelatin zymography was carried out. GPG downregulated the expression of matrix metalloproteinase-2 in a concentration-dependent manner. Furthermore, GPG significantly disrupted bFGF-induced neovascularization on the chick chorioallantoic membrane assay in vivo. These results suggest that 3-O--D-galactopyranosylglyceride may inhibit neovascularization by inhibiting angiogenic activity of endothelial cells via regulation of matrix metalloproteinase-2 (MMP-2).

• The Journal of Internal Korean Medicine
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• v.40 no.3
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• pp.425-442
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• 2019

Objectives: This study aimed to reveal the pharmacological properties of the newly prescribed herbal mixture, Chenmadansamgamibokhap-tang(CDBT), against hypoxia-induced neuronal cell injury (especially mouse hippocampal neuronal cell line, HT-22 cells) and their corresponding mechanisms. Methods: A cell-based in vitro experiment, in which a hypoxia condition induced neuronal cell death, was performed. Various concentrations of the CDBT were pre-treated to the HT-22 cells for 4 h before 18 h in the hypoxia chamber. The glial cell BV-2 cells were stimulated with $IFN{\gamma}$ and LSP to produce inflammatory cytokines and reactive oxygen species. When the neuronal HT-22 cells were treated with this culture solution, the drug efficacy against neuronal cell death was examined. Results: CDBT showed cytotoxicity in the normal condition of HT-22 cells at a dose of $125{\mu}g/mL$ and showed a protective effect against hypoxia-induced neuronal cell death at a dose of $31.3{\mu}g/mL$. CDBT prevented hypoxia-induced neuronal cell death in a dose-dependent manner in the HT-22 cells by regulating $HIF1{\alpha}$ and cell death signaling. CDBT prevented neuronal cell death signals and DNA fragmentation due to the hypoxia condition. CDBT significantly reduced cellular oxidation, cell death signals, and caspase-3 activities due to microglial cell activations. Moreover, CDBT significantly ameliorated LPS-induced BV-2 cell activation and evoked cellular oxidation through the recovery of redox homeostasis. Conclusions: CDBT cam be considered as a vital therapeutic agent against neuronal cell deaths. Further studies are required to reveal the other functions of CDBT in vivo or in the clinical field.