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Wyszukujesz frazę "Choi, Jung" wg kryterium: Autor


Wyświetlanie 1-4 z 4
Tytuł:
Defect Detection Using Deep Learning-Based YOLOv3 in Cross-Sectional Image of Additive Manufacturing
Autorzy:
Choi, Byungjoo
Choi, Yongjun
Lee, Moon-Gu
Kim, Jung-Sub
Lee, Sang-Won
Jeon, Yongho
Powiązania:
https://bibliotekanauki.pl/articles/2048889.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
additive manufacturing
deposition defect
data augmentation
YOLOv3
object detection
Opis:
Deposition defects like porosity, crack and lack of fusion in additive manufacturing process is a major obstacle to commercialization of the process. Thus, metallurgical microscopy analysis has been mainly conducted to optimize process conditions by detecting and investigating the defects. However, these defect detection methods indicate a deviation from the operator’s experience. In this study, artificial intelligence based YOLOv3 of object detection algorithm was applied to avoid the human dependency. The algorithm aims to automatically find and label the defects. To enable the aim, 80 training images and 20 verification images were prepared, and they were amplified into 640 training images and 160 verification images using augmentation algorithm of rotation, movement and scale down, randomly. To evaluate the performance of the algorithm, total loss was derived as the sum of localization loss, confidence loss, and classification loss. In the training process, the total loss was 8.672 for the initial 100 sample images. However, the total loss was reduced to 5.841 after training with additional 800 images. For the verification of the proposed method, new defect images were input and then the mean Average Precision (mAP) in terms of precision and recall was 0.3795. Therefore, the detection performance with high accuracy can be applied to industry for avoiding human errors.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 4; 1037-1041
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural, Electrical, and Optical Properties of ZnO Films Grown by Atomic Layer Deposition at Low Temperature
Autorzy:
Park, Ji-Young
Weon, Ye Bin
Jung, Myeong Jun
Choi, Byung Joon
Powiązania:
https://bibliotekanauki.pl/articles/2174578.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
zinc oxide
ZnO
atomic layer deposition
low temperature growth
optoelectronic properties
Opis:
Zinc oxide (ZnO) is a prominent n-type semiconductor material used in optoelectronic devices owing to the wide bandgap and transparency. The low-temperature growth of ZnO thin films expands diverse applications, such as growth on glass and organic materials, and it is also cost effective. However, the optical and electrical properties of ZnO films grown at low temperatures may be inferior owing to their low crystallinity and impurities. In this study, ZnO thin films were prepared by atomic layer deposition on SiO2 and glass substrates in the temperature range of 46-141℃. All films had a hexagonal würtzite structure. The carrier concentration and electrical conductivity were also investigated. The low-temperature grown films showed similar carrier concentration (a few 1019 cm-3 at 141°C), but possessed lower electrical conductivity compared to high-temperature (>200°C) grown films. The optical transmittance of 20 nm thin ZnO film reached approximately 90% under visible light irradiation. Additionally, bandgap energies in the range of 3.23-3.28 eV were determined from the Tauc plot. Overall, the optical properties were comparable to those of ZnO films grown at high temperature.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 4; 1503--1506
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Friction and Wear Behavior of Direct Metal Deposition on SUH3
Autorzy:
Choi, Byungjoo
Cho, In-Sik
Jung, Do-Hyun
Lee, Moon G.
Jeon, Yongho
Powiązania:
https://bibliotekanauki.pl/articles/352111.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
direct metal deposition
heat pretreatment
friction test
wear test
micro-hardness
Opis:
Poppet valves made from high-frequency heat-treated SUH3 steel have insufficient durability, and scratches appear on the valve face in prolonged use. It is necessary to develop surface treatment technology with excellent durability to prevent the deterioration of engine performance. Therefore, a surface treatment technology with higher abrasion resistance than existing processes was developed by direct metal deposition to the face where the cylinder and valve are closed. In this study, heat pretreatment and deposition tests were performed on three materials to find suitable powders. In the performance evaluation, the hardness, friction coefficient, and wear rate were measured. Direct metal deposition using Inconel 738 and Stellite 6 powders without heat pretreatment were experimentally verified to have excellent durability.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 841-844
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Corrosion Behavior of Hastelloy® C-2000® Ni-Cr-Mo-Fe Alloys in the Entrained-Flow Coal Gasification Syngas Plants
Autorzy:
Lee, Sungkyu
Kim, Min-Jung
Choi, Nuri
Hwang, Sang Yeon
Chung, Seok-Woo
Lee, Seung-Kong
Yun, Yongseung
Powiązania:
https://bibliotekanauki.pl/articles/352403.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mixed oxidant corrosion
Hastelloy® C-2000® Ni-Cr-Mo-Fe alloy
coal gasification
high temperature halogencorrosion
hydrated chlorides
Opis:
A mechanistic exposure experiment was performed on the commercially available and welded Ni-Cr-Mo-Fe alloy samples used in the piping materials of the coal gasification pilot plant. Thermodynamic Ellingham-Pourbaix stability diagrams were constructed to provide insight into the mechanism of the observed corrosion behavior. The thermodynamic inference on the corrosion mechanism was supplemented with the morphological, compositional and microstructural analyses of the exposed samples using scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy analyses. X-ray diffraction result revealed stable corrosion products of NiO, MoNi4 and Cr4.6 MoNi2.1 after accumulated total exposure duration of 139 h to the corrosive atmosphere. Scanning electron microscopy and energy-dispersive X-ray spectroscopy positively identified formation of rather continuous and adherent pre-oxidation corrosion products although extensively peeled-off oxides were finally observed as corrosion scales on the post-exposure alloy samples, which were attributed to the chlorination/oxidation into thin (spalled) oxides.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 2; 869-878
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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