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A Study of the Mixing Characteristics for Cavity Sizes in SCRamjet Engine Combustor
Hyungseok Seo,Hui Jeong,이재우,Yunghwan Byun 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.5
Recently, interest has been shown in utilizing hypersonic vehicles for the purpose of flight transfer to supersonic or hypersonic. In particular, the SCRamjet Engine which is the propulsion system for a hypersonic vehicle has been studied to see if it is able to run. However, most research related to the SCRamjet doesn’t provide detailed results. Therefore, the result of SCRamjet research is done in an e-science AHM in order to share advanced resources and to allow collaborative research. Airflow into the combustor of a scramjet engine stays inside for a very short time i.e. on the order of milliseconds. Since the whole process of combustion has to be completed during this short duration, research on supersonic combustion technologies is of great significance. Of the many technologies, this study is concerned with methods that improve the air-fuel mixture efficiency. By selecting a method that uses a cavity and vertical jet injection, this study investigates the characteristics of the flow field by using both numerical analysis and experimental methods. The cavity size alone is varied while the length-height ratio (L/H) of the cavity is fixed at 1, and the sonic jet is injected vertically through a 1-mm-diameter nozzle downstream of the cavity. A numerical analysis reveals that larger cavities correspond to larger vortices, which is a measure of the air - fuel mixture. Specifically, near the bottom of the combustor (y/D = 5), where mixing is most active, large vorticities are seen. Furthermore, for a comparison and verification of the results of the numerical analysis, visualization using shadowgraphs and measurements of the pressure using pressure sensitive paint (PSP) are conducted in the supersonic wind tunnel at Konkuk University. Allowing for better understanding of the physics of the flow, the visualization results show good qualitative agreement with regards to the shape of the shockwaves and changes in the shear-layer thickness while the results from the pressure measurements confirm that the analysis results are close to the experimental results. Recently, interest has been shown in utilizing hypersonic vehicles for the purpose of flight transfer to supersonic or hypersonic. In particular, the SCRamjet Engine which is the propulsion system for a hypersonic vehicle has been studied to see if it is able to run. However, most research related to the SCRamjet doesn’t provide detailed results. Therefore, the result of SCRamjet research is done in an e-science AHM in order to share advanced resources and to allow collaborative research. Airflow into the combustor of a scramjet engine stays inside for a very short time i.e. on the order of milliseconds. Since the whole process of combustion has to be completed during this short duration, research on supersonic combustion technologies is of great significance. Of the many technologies, this study is concerned with methods that improve the air-fuel mixture efficiency. By selecting a method that uses a cavity and vertical jet injection, this study investigates the characteristics of the flow field by using both numerical analysis and experimental methods. The cavity size alone is varied while the length-height ratio (L/H) of the cavity is fixed at 1, and the sonic jet is injected vertically through a 1-mm-diameter nozzle downstream of the cavity. A numerical analysis reveals that larger cavities correspond to larger vortices, which is a measure of the air - fuel mixture. Specifically, near the bottom of the combustor (y/D = 5), where mixing is most active, large vorticities are seen. Furthermore, for a comparison and verification of the results of the numerical analysis, visualization using shadowgraphs and measurements of the pressure using pressure sensitive paint (PSP) are conducted in the supersonic wind tunnel at Konkuk University. Allowing for better understanding of the physics of the flow, the visualization results show good qualitative agreement with regards to the shape of the shockwaves and changes in the shear-layer thickness while the results from the pressure measurements confirm that the analysis results are close to the experimental results.
Automatic Registration between EO and IR Images of KOMPSAT-3A Using Block-based Image Matching
Hyungseok Kang 대한원격탐사학회 2020 大韓遠隔探査學會誌 Vol.36 No.4
This paper focuses on automatic image registration between EO (Electro-Optical) and IR (InfraRed) satellite images with different spectral properties using block-based approach and simple preprocessing technique to enhance the performance of feature matching. If unpreprocessed EO and IR images from Kompsat-3A satellite were applied to local feature matching algorithms (Scale Invariant Feature Transform, Speed-Up Robust Feature, etc.), image registration algorithm generally failed because of few detected feature points or mismatched pairs despite of many detected feature points. In this paper, we proposed a new image registration method which improved the performance of feature matching with block-based registration process on 9-divided image and pre-processing technique based on adaptive histogram equalization. The proposed method showed better performance than without our proposed technique on visual inspection and I-RMSE. This study can be used for automatic image registration between various images acquired from different sensors.
Anaesthetic experience in a patient with severe thoracolumbar kyphosis -A case report-
Hyungseok Seo,Sung-Hoon Kim,Tae-in Ham,하승일 대한마취통증의학회 2012 Anesthesia and pain medicine Vol.7 No.3
Kyphosis is a deformity characterized by anterior flexion of the vertebral column. When severe, kyphosis may decrease lung volume and compliance, leading to increased work of breathing and deterioration of pulmonary function. Moreover, postoperative respiratory failure is a common problem for patients with severe spinal deformities. We describe the successful case of general anaesthesia in a 71-year-old male patient with severe thoracolumbar kyphosis undergoing open surgery converted from robotic surgery.
Hyungseok Hong,전형탁,Honggyu Kim,Hyungchul Kim,Sanghyun Woo,Seokhoon Kim,Seokhwan Bang,Seungjun Lee,Sunyeol Jeon,Wooho Jeong 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.4
We investigated the physical and the electrical properties of HfO₂ films grown by using a remote-plasma atomic layer deposition technique on a pre-deposited Hf metal layer. The Hf metal pre-deposited film retarded effectively the growth of an interfacial layer while the HfO₂ film without a Hf metal layer showed a growth of an interfacial layer. The as-deposited HfO₂ layers on thick Hf metal layers are crystallized while those on thin Hf metal layers remain amorphous. The pre-deposited Hf metal layer decreased the equivalent oxide thickness while it increased the crystallization temperature. The flat-band voltage (VFB) shifted in the negative direction with increasing pre-deposited Hf metal thickness and the effective fixed oxide charge density corresponding to the △VFB of the HfO₂ films increased with increasing pre-deposited Hf metal thickness. After annealing at 800℃, the VFB for the HfO₂ films shifted toward the ideal VFB and the effective fixed oxide charge decreased. The Hf pre-deposition technique was found to be effective in reducing the EOT by suppressing interfacial layer growth while the electrical properties, such as the leakage current density and the effective fixed oxide charge density, were degraded. We investigated the physical and the electrical properties of HfO₂ films grown by using a remote-plasma atomic layer deposition technique on a pre-deposited Hf metal layer. The Hf metal pre-deposited film retarded effectively the growth of an interfacial layer while the HfO₂ film without a Hf metal layer showed a growth of an interfacial layer. The as-deposited HfO₂ layers on thick Hf metal layers are crystallized while those on thin Hf metal layers remain amorphous. The pre-deposited Hf metal layer decreased the equivalent oxide thickness while it increased the crystallization temperature. The flat-band voltage (VFB) shifted in the negative direction with increasing pre-deposited Hf metal thickness and the effective fixed oxide charge density corresponding to the △VFB of the HfO₂ films increased with increasing pre-deposited Hf metal thickness. After annealing at 800℃, the VFB for the HfO₂ films shifted toward the ideal VFB and the effective fixed oxide charge decreased. The Hf pre-deposition technique was found to be effective in reducing the EOT by suppressing interfacial layer growth while the electrical properties, such as the leakage current density and the effective fixed oxide charge density, were degraded.