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Modified Chitosan Scaffold for Tissue Engineering
( Myungchul Lee ),( Kyoung-je Jang ),( Sang Bae Park ),( Jaewoon Lim ),( Hyun-mok Son ),( Jae Eun Kim ),( Jong Hoon Chung ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.2
Damage to the eardrum causes acute pain and can lead to chronic otitis media if it develops into chronic tympanic membrane (TM) perforations. The chronic TM perforations are usually treated with surgical methods such as tympanoplasty and myringoplasty. However, the surgeries are not only complicated and difficult but also cost a lot of money. Our research team developed chitosan patches (E-CPs) that release epidermal growth factor (EGF) as a patch therapy to replace surgical methods. However, there was a limitation in the healing ratio of the treatment compared to the surgical methods. In this study, we developed an EGF and epidermal growth factor receptor (EGFR) gene-releasing polyethyleneimine (PEI)/chitosan patches (EErP-CPs) to increase the regeneration of TM perforations. The addition of PEI increased the adhesion and migration ability of TM cells on the patches. The simultaneous release of the EGF and EGFR gene further enhanced TM cell proliferation, adhesion and migratory ability. It was confirmed that the EGF protein and EGFR gene were released for 30 days, however EGF was released and increased TM cell viability almost immediately after treatment and EGFR took minimum of 3 days before showing its effect on improved cell viability. It was also shown that EErP-CPs are more hydrophilic and have more positive charge than E-CP because of added amine groups from PEI. In conclusion, the developed EErP-CPs resulted in improved healing of TM perforations and can potentially be applied to the regeneration of both chronic and acute tympanic membrane perforations.
Examination for Evaluating Degradation of Guide Tubes in Spent Fuel Assembly
Myungchul Park,Sunggeun Kim,Jaehan Kim,Sukwoo Hong,Hyojik Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
The skeleton of fuel assembly is composed of top nozzle, bottom nozzle, grids, and guide tubes. In the reactor core, all the parts of the fuel assembly suffer degradations due to the condition of high temperature, pressure and water environment. Therefore, many material properties of high temperature mechanical strength, corrosion and irradiation resistance have been considered to choose the material for fuel assembly parts in the fuel development stage. The guide tubes have important roles to connect each parts and support the load of fuel assembly while the fuel is lifted. In Westinghouse 14×14 standard fuel assembly, Zircaloy-4 was used for the material of the guide tubes. Zircaloy-4 has a resistance to water corrosion and maintain good mechanical properties after the discharge from the core, so this alloy is also utilized for a fuel rod cladding material although the microstructure is slightly different due to the heat treatment difference. Thus, it is expected that there is no issue regarding the guide tube integrity after the discharge and during the storage in the pool, especially in case of low burn-up. However, the surface oxidation and resultant hydrogen pick-up can affect to the embrittlement to the Zr alloy. So, it is needed to know the actual status of spent fuel assembly by performing post-irradiation examination. In this study, the degradation level of the guide Tubes in low burn-up spent fuel assembly was investigated using the KAERI PIE facility in order to make some data which can be utilized to the baseline for evaluating the integrity of the spent fuel skeleton.
( Myungchul Lee ),( Hoon Seonwoo ),( Kyoung-je Jang ),( Sangbae Park ),( Jong Hoon Chung ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1
There are viral methods, chemical methods and physical methods to transfer a gene to mammalian cells. Among these methods, viral methods have potential danger such as risk of immunogenicity and infection of host cells. Thus, many researchers are developing novel non-viral transfection methods. In this study, we developed the novel non-viral carrier for gene transfection using horse bone (HB) and polyethyleneimine (PEI) (HBP). The advantages of this carrier are that it was developed using agricultural by-products and that is non-viral vector. We got the horse bones from slaughter in Jeju-island, South Korea. These horse bone samples were immersed in H2O2 for bleaching and dried. After the drying, the samples were sintered in electric furnace at 900°C for 2 hours. Then, the sintered samples were ground into a powder using grinder and ball miller. By filtering, it were classified under 20 μm. XRD, FT-IR and XRF were performed for characterization of horse bone powder. To make HBP complex, we mixed PEI and HB into different concentrations. Then, we characterized size and surface potential of HBP using DLS. To perform gene transfection, NIH-3T3 cells were seeded at a density of 2x105 cells/mL. After 2 days, HBP- target gene were treated. Then, we checked gene transfection efficiency by turbo GFP assay, luciferase assay and FACS aria assay. As a results, we confirmed HBP have more positive charge than only PEI and discovered that HBP have higher transfection efficiency than only PEI for mammalian cells. Our works suggest the novel gene carrier using natural animal bone as agricultural by products.
A Novel Architecture of Asynchronous Sorting Engine Module for ASIC Design
Myungchul Yoon 대한전자공학회 2022 Journal of semiconductor technology and science Vol.22 No.4
A novel sorting engine called Sorting Grid (SG) is presented in this paper. SG is intended to be used as a hardware module for ASIC design which can be employed for any ASIC chip requiring fast sorting operation. The SG is implemented by simple modular architecture so that it is easily synthesized with conventional ASIC tools. SG allows inputs with the same key and provides stable sorting for those inputs. SG sorts m-bit N binary inputs in (m+1) cycles with variable cycle time. SG employs a self-timed asynchronous clock of which the period changes according to the operation time of each cycle. The clock period greatly decreases along the cycle. With this clock and a multi-level bypassing scheme, SG has O(N+m) time-complexity for pseudo-random binary inputs. By the simulations with 1.2V-0.13 μm process technology, the sorting rate of the SG is about 1 ns per input for 16-bit inputs.
A VLSI Design for Scalable High-Speed Digital Winner-Take-All Circuit
Myungchul Yoon 대한전자공학회 2015 Journal of semiconductor technology and science Vol.15 No.2
A high speed VLSI digital Winner-Take-All (WTA) circuit called simultaneous digital WTA (SDWTA) circuit is presented in this paper. A minimized comparison-cell (w-cell) is developed to reduce the size and to achieve high-speed. The w-cell which is suitable for VLSI implementation consists of only four transistors. With a minimized comparison cell structure SDWTA can compare thousands of data simultaneously. SDWTA is scalable with O(mlog n) time-complexity for n of m-bit data. According to simulations, it takes 16.5 ns with 1.2V-0.13 mm process technology in finding a winner among 1024 of 16-bit data.
A Fast (7, 3)-adder Circuit for High-speed Multiplier Design
Myungchul Yoon 대한전자공학회 2022 IEIE Transactions on Smart Processing & Computing Vol.11 No.4
A set of fast (m, 3)-adder circuits (4 ≤ m ≤ 7) is presented in this paper. An (m, 3)-adder adds m bits at a time and produces three outputs (N, C, S). These adders are designed to implement high-speed (7, 3)-adder based multipliers that use a (7, 3)-adder as a basic unit and five other adders ((6, 3), (5, 3), (4, 3), (3, 2), and (2, 2)-adder) as auxiliary units for the addition of partial products. Multipliers require adding tens of partial products to obtain a result, and they can be added by (7, 3)-adders more quickly than by (3, 2)-adders. In simulation results, the worst-case delay and power of the new (7, 3)-adder are 1.45 times and 2.4 times larger than those of the reference (3, 2)-adder. However, the parallel addition of partial products with the (7, 3)-adder is faster and consumes less power than with the (3, 2)-adder because the (7, 3)-adder based multiplier requires fewer adders and addition stages than a (3, 2)-adder based multiplier. This result shows that the speed of a multiplier can be increased by using (7, 3)-adders instead of (3, 2)-adders in reducing partial products.