A Study on the PV Simulator using Multiphase buck converter

( Zhengguo Piao ) 조선대학교 공학기술연구원 2014 공학기술논문지 Vol.7 No.1

For a better researching and utilization of the photovoltaic system, this paper presents a design method for the photovoltaic simulator based on multiphase buck converter and DSP controller. The control mechanism is based on a more precise calculation method with current mode controller. With the new control strategy, this PV simulator can simulate the output characteristics of any types PV arrays under different working conditions. An actual PV simulator has been built and tested with a variable resistive load and a constant power load as well. The experiment result shows that the output characteristics of the PV simulator are consistent with the actual PV arrays’ and the PV simulator could also shift smoothly on its I-V characteristics.

Axin2 overexpression promotes the early epithelial disintegration and fusion of facial prominences during avian lip development

Tak, Hye-Jin,Piao, Zhengguo,Kim, Hak-Jin,Lee, Sang-Hwy Springer-Verlag 2018 Development genes and evolution Vol.228 No.5

Mineralized Polysaccharide Transplantation Modules Supporting Human MSC Conversion into Osteogenic Cells and Osteoid Tissue in a Non-Union Defect

Qing Ge,David William Green,이동준,김현이,Zhengguo Piao,이종민,정한성 한국분자세포생물학회 2018 Molecules and cells Vol.41 No.12

Regenerative orthopedics needs significant devices to transplant human stem cells into damaged tissue and encourage automatic growth into replacements suitable for the human skeleton. Soft biomaterials have similarities in mechanical, structural and architectural properties to natural extracellular matrix (ECM), but often lack essential ECM molecules and signals. Here we engineer mineralized polysaccharide beads to transform MSCs into osteogenic cells and osteoid tissue for transplantation. Bone morphogenic proteins (BMP-2) and indispensable ECM proteins both directed differentiation inside alginate beads. Laminin and collagen IV basement membrane matrix proteins fixed and organized MSCs onto the alginate matrix, and BMP-2 drove differentiation, osteoid tissue self-assembly, and small-scale mineralization. Augmentation of alginate is necessary, and we showed that a few rationally selected small proteins from the basement membrane (BM) compartment of the ECM were sufficient to upregulate cell expression of Runx-2 and osteocalcin for osteoid formation, resulting in Alizarin red-positive mineral nodules. More significantly, nested BMP-2 and BM beads added to a non-union skull defect, self-generated osteoid expressing osteopontin (OPN) and osteocalcin (OCN) in a chain along the defect, at only four weeks, establishing a framework for complete regeneration expected in 6 and 12 weeks. Alginate beads are beneficial surgical devices for transplanting therapeutic cells in programmed (by the ECM components and alginate-chitosan properties) reaction environments ideal for promoting bone tissue.

Evaluation of facial soft tissue thickness in asymmetric mandibular deformities after orthognathic surgery

Luo Huang,Zhicong Li,Jing Yan,Lunqiu Chen,Zhengguo Piao 대한악안면성형재건외과학회 2021 Maxillofacial Plastic Reconstructive Surgery Vol.43 No.-

Objectives: The purpose of this study was to compare differences in facial soft tissue thickness in three-dimensional(3D) images before and after orthognathic surgery in patients with skeletal Class III malocclusion and to obtain a betterunderstanding of the relationship between hard and soft tissue changes after surgery. Materials and method: The present retrospective study included 31 patients with skeletal Class III malocclusion withmandibular chin deviation greater than 4 mm who had undergone cone-beam computed tomography before and 6months after surgery. Seven bilateral points were established. Measurements were taken from software-generatedmultiplanar reconstructions. The predictor variables were timing (pre- and postoperatively) and side (deviated vs. nondedicated). A regression model and correlation analysis were conducted for statistical analysis. Results: The difference of bilateral facial soft tissue thickness was statistically significantly different between deviatedand nondeviated sides (P < 0.05), with lower values observed on the deviated side. The soft tissue thickness hasbecome nearly symmetric at local regions of the lower thirds of the face after orthognathic surgery. However, mostmeasurements showed a negative correlation between changes in soft tissue thickness and changes in bone tissues. Conclusions: Skeletal Class III malocclusion with facial asymmetry is accompanied by differences in soft tissuethickness when comparing Dev and N-Dev sides of the posterior region of the mandible, where soft tissues are thinneron the Dev side. Soft tissue thickness can compensate for or camouflage the underlying asymmetric mandible. Inaddition, the asymmetric soft tissue thickness on the lower third of the face can be partially improved by orthognathicsurgery, but the amount of soft tissue thickness change is not consistent with that of hard tissue positional change.

Accuracy Assessment of Image-Based Surface Meshing for Volumetric Computed Tomography Images in the Craniofacial Region

Kang, Sang-Hoon,Kim, Moon-Key,Kim, Hak-Jin,Zhengguo, Piao,Lee, Sang-Hwy by Mutaz B. Habal, MD. 2014 JOURNAL OF CRANIOFACIAL SURGERY - Vol.25 No.6

BACKGROUND: Three-dimensional printing and computer-assisted surgery demand a high-precision three-dimensional mesh model created from computed tomography (CT) imaging data using an image-based meshing algorithm. We aimed to evaluate the three-dimensional geometric accuracy of surface meshes produced from CT images with commercially available software packages. METHODS: The CT images were acquired for 3 human dry skulls and 10 manufactured plastic skulls. Four commercially available software packages were used to produce the surface meshes in stereolithography (STL) file format. These CT-based STL surface meshes were registered and compared with three-dimensional optical-scanned reference mesh surface for evaluating the accuracy of the STL mesh produced with each software package. RESULTS: The surface geometries produced by the CT-image–based meshing process were all relatively accurate; differences from the three-dimensional optical-scanned data were in the voxel or subvoxel range. However, when comparisons with the three-dimensional optical-scanned surface data were performed in individual anatomic regions, we found significantly different accuracies of the CT-based STL surface meshes produced by the different software packages. CONCLUSIONS: We found that all 4 software packages showed reasonably good meshing accuracies for clinical use. However, the range of errors inherent in the CT-image–based meshing process demands that caution should be taken in selecting and manipulating the software to avoid potential errors in specific clinical applications.

Erk AND RETINOIC ACID SIGNALING PARTICIPATE IN THE SEGREGATION AND PATTERNING OF FIRST ARCH DERIVED MAXILLA AND MANDIBLE

박은주,탁혜진,박은하,백정미,이상휘,Park, Eun-Ju,Tak, Hye-Jin,Park, Eun-Ha,Baik, Jeong-Mi,Zhengguo, Piao,Lee, Sang-Hwy Korean Association of Maxillofacial Plastic and Re 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.2

In vertebrates, the face is mainly formed with neural crest derived neural crest cells by the inherent programs and the interactive environmental factors. Extracellular signaling-regulated kinase (Erk) is one of such programs to regulate the various cellular functions. And retinoic acid (RA) also plays an important role as a regulator in differentiation process at various stages of vertebrate embryogenesis. We wanted to know that the segregation as well as the patterning of maxillary and mandibular structure is greatly influenced by the maxillomandibular cleft (MMC) and the failure of this development may result in the maxillomandibular fusion (syngnathia) or other patterning related disorder. It has been well documented that the epithelium at this cleft region has significant expression of Fibroblast growth factor (Fgf) 8, and it is essential for the patterning of the first arch derived structures. By the morphological, skeletal, cell proliferation and apoptotic, and hybridization analysis, we checked the effects of Erk inhibition and/or RA activation onto MMC and could observe that Erk and RA signaling is individually and synergically involved in the facial patterning in terms of FGF signaling pathway via Barx-l. So RA and Erk signaling work together for the MMC patterning and the segregation of maxilla-mandible by controlling the Fgf-related signaling pathways. And the abnormality in MMC brought by aberrant Fgf signaling may result in the disturbances of maxillary-mandibular segregation.