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.

Body-mediated Bioelectronics without Battery, Wiring, and Even Generator: Application of Biocompatible and Conductive Polymers

Hyungseok Yong(용형석),이상민,홍진기 한국고분자학회 2023 한국고분자학회 학술대회 연구논문 초록집 Vol.48 No.2

Challenging Similarity in Biosimilar Development

Hyungseok CHOI,Byungje SUNG,Jiseon YOO,Jongkwang HONG,Heesung KIM 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.4

Effect of thiophenol-based ligands on photoluminescence of quantum dot nanocrystals

Hyungseok Moon,Hoseok Jin,Bokyoung Kim,Hyunjin Kang,Daekyoung Kim,Heeyeop Chae 한국진공학회 2016 한국진공학회 학술발표회초록집 Vol.2016 No.2

Observation of the Response of Central Nervous System with Changes in Illuminance and Color Temperature in Learning Environment

( Hyungseok-jo ),( Kyubeom-kim ),( Seokhuen-ahn ),( Namhun-her ),( Sanghyeok-seo ),( Youngjung-kim ),( Byungchan-min ) 한국감성과학회 2019 한국감성과학회 국제학술대회(ICES) Vol.2019 No.-

The purpose of this study was to observe the correlation between illuminance and the color temperature that is suitable for the learning environment through the EEG. According to the characteristics of the color temperature it was divided into 3000K, 4000K, 6500K. The illuminance was set at 400lx and 1000lx as the KS standards. UK test was performed in each lighting situation. During the experiment, EEG were measured to see the central nervous system response. The experiment included 12 male that experienced learning in the classroom and reading room. The EEG were sampled at 512Hz using a TAOS VITALBRAIN, and the detected raw data were filtered through a 60Hz noise filter. After filtering, frequency analysis was performed. And power spectrum analysis was performed for αwave and βwave. We analyzed differences in the EEG based on the different lighting by 2-way ANOVA and post-hoc tests. The results of the study showed that a significant difference exists in terms of the EEG based on the illuminance and color temperature(p<0.05). Regarding the alpha power, 3000K-1000lx was higher than other lighting.

Executive Compensation When a Firm is a Business Group Member

Hyungseok Kim,Woochan Kim 한국재무학회 2014 한국재무학회 학술대회 Vol.2014 No.05

This paper examines how executive pay is set when a firm is a business group member. Using Korea as a laboratory setting, we find that member firm’s cash compensation for its executives is strongly linked to the stock performance of other members as well as its own. Further analyses reveal that this link to other members’ performance is consistent with the hypothesis of corporate resources being tunneled from one member to another for the benefit of the controlling family. We find that the link is stronger in firms with high control-ownership disparity or low foreign ownership. We also find that the link is tighter to the performance of firms directly owned by the controlling family.

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.

Metallically Conducting Fibers by in-situ Hybridization of Polymer and Metal Nanoparticle during Wet Spinning

Hyungseok Lee,Taeho Lee,Jun Young Lee 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Characteristics of Atomic-Layer-Deposited HfO2 Films by Using a Remote Plasma on Pre-Deposited Hf Metal Layer

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.

Triboelectric Nanogenerators Using Robust Silver Nanowires Network

Hyungseok Kang,Han Kim,Seongsu Kim,Hyeon Jin Shin,Siuk Cheon,Ji-Hyeok Huh,Dong Yun Lee,Seungwoo Lee,Sang-Woo Kim,Jeong Ho Cho 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2