13 results on '"Jaegeun Park"'
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2. Virtual Coupling of Railway Vehicles: Gap Reference for Merge and Separation, Robust Control, and Position Measurement
- Author
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Byung-Hun Lee, Yongsoon Eun, and Jaegeun Park
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Nonlinear system ,Jerk ,Control theory ,Computer science ,Mechanical Engineering ,Automotive Engineering ,Operational efficiency ,Train ,Imperfect ,Robust control ,Error detection and correction ,Sliding mode control ,Computer Science Applications - Abstract
Virtual coupling, which refers to the operation of railway vehicles that enables the merge and separation of vehicles on the move by controlling the gap between the vehicles without any mechanical coupling, is one of the technologies for increasing the transport capacity and enhancing operational efficiency. This paper proposes a robust gap controller based on sliding mode control with a nonlinear train model with uncertainties. Additionally, a gap reference generation scheme is developed that ensures that the merge and separation of two trains is completed before a given location and respects constraints on acceleration and jerk. The position and velocity measurement errors arising from imperfect knowledge of wheel diameters are also considered, and a new error correction scheme is proposed to reduce the perturbation in the gap control performance. The proposed schemes are validated through simulations.
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- 2022
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3. A Resiliency Coordinator Against Malicious Attacks for Cyber-Physical Systems
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Yongsoon Eun, Jaegeun Park, Yechan Jeong, Daehoon Kim, and Kyung-Joon Park
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- 2022
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4. A list of guest‐star records in Korean history and their possible counterparts
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Jaegeun Park, Junhyeok Jeon, and Hongjun An
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Space and Planetary Science ,Astronomy and Astrophysics - Published
- 2022
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5. Automatic Diagnosis and Real-Time Monitoring Software for Train Control Systems
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Yongsoon Eun, Dong-Jin Suh, Jaegeun Park, and Yuchang Won
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Software ,Control and Systems Engineering ,business.industry ,Computer science ,Applied Mathematics ,Embedded system ,Control system ,Cyber-physical system ,business - Published
- 2021
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6. X-Ray Studies of the Pulsar PSR J1420–6048 and Its TeV Pulsar Wind Nebula in the Kookaburra Region
- Author
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Jaegeun Park, Chanho Kim, Jooyun Woo, Hongjun An, Kaya Mori, Stephen P. Reynolds, and Samar Safi-Harb
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Space and Planetary Science ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We present a detailed analysis of broadband X-ray observations of the pulsar PSR J1420-6048 and its wind nebula (PWN) in the Kookaburra region with Chandra, XMM-Newton, and NuSTAR. Using the archival XMM-Newton and new NuSTAR data, we detected 68 ms pulsations of the pulsar and characterized its X-ray pulse profile which exhibits a sharp spike and a broad bump separated by ~0.5 in phase. A high-resolution Chandra image revealed a complex morphology of the PWN: a torus-jet structure, a few knots around the torus, one long (~7') and two short tails extending in the northwest direction, and a bright diffuse emission region to the south. Spatially integrated Chandra and NuSTAR spectra of the PWN out to 2.5' are well described by a power law model with a photon index ${\Gamma} {\approx}$ 2. A spatially resolved spectroscopic study, as well as NuSTAR radial profiles of the 3--7 keV and 7--20 keV brightness, showed a hint of spectral softening with increasing distance from the pulsar. A multi-wavelength spectral energy distribution (SED) of the source was then obtained by supplementing our X-ray measurements with published radio, Fermi-LAT, and H.E.S.S. data. The SED and radial variations of the X-ray spectrum were fit with a leptonic multi-zone emission model. Our detailed study of the PWN may be suggestive of (1) particle transport dominated by advection, (2) a low magnetic-field strength (B ~ 5${\mu}$G), and (3) electron acceleration to ~PeV energies., Comment: 18 pages and 8 figures. Accepted for publication in Apj
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- 2023
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7. A Broadband X-Ray Study of the Rabbit Pulsar Wind Nebula Powered by PSR J1418-6058
- Author
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Jaegeun Park, Chanho Kim, Jooyun Woo, Hongjun An, Kaya Mori, Stephen P. Reynolds, and Samar Safi-Harb
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Space and Planetary Science ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We report on broadband X-ray properties of the Rabbit pulsar wind nebula (PWN) associated with the pulsar PSR J1418-6058 using archival Chandra and XMM-Newton data, and a new NuSTAR observation. NuSTAR data above 10 keV allowed us to detect the 110-ms spin period of the pulsar, characterize its hard X-ray pulse profile, and resolve hard X-ray emission from the PWN after removing contamination from the pulsar and other overlapping point sources. The extended PWN was detected up to $\sim$20 keV and is well described by a power-law model with a photon index $\Gamma\approx$2. The PWN shape does not vary significantly with energy, and its X-ray spectrum shows no clear evidence of softening away from the pulsar. We modeled the spatial profile of X-ray spectra and broadband spectral energy distribution in the radio to TeV band to infer the physical properties of the PWN. We found that a model with low magnetic field strength ($B\sim 10$ $\mu$G) and efficient diffusion ($D\sim 10^{27}$ cm$^2$ s$^{-1}$) fits the PWN data well. The extended hard X-ray and TeV emission, associated respectively with synchrotron radiation and inverse Compton scattering by relativistic electrons, suggests that particles are accelerated to very high energies ($\gtrsim500$ TeV), indicating that the Rabbit PWN is a Galactic PeVatron candidate., Comment: 21 pages, 10 figures. ApJ accepted
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- 2023
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8. An Attack-Resilient CPS Architecture for Hierarchical Control: A Case Study on Train Control Systems
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Insup Lee, Yongsoon Eun, Sang H. Son, Kyung-Joon Park, Haegeon Jeong, In-Hee Park, Yuchang Won, Jaegeun Park, Kyungtae Kang, Buyeon Yu, and Jeanseong Baik
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0209 industrial biotechnology ,General Computer Science ,business.industry ,Computer science ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,Control (management) ,Testbed ,020206 networking & telecommunications ,02 engineering and technology ,020901 industrial engineering & automation ,Computer architecture ,Control system ,0202 electrical engineering, electronic engineering, information engineering ,Wireless ,Hierarchical control system ,Architecture ,business ,Resilience (network) - Abstract
This article presents an attack-resilient architecture for cyber-physical systems (CPSs). As a case study, the authors build a radio-based train control testbed and validate the proposed resilient design architecture. The target CPS application is a hierarchical control system.
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- 2018
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9. Attack Resilient State Estimation by Sensor Output Coding
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Yongsoon Eun, Jaegeun Park, and Gyujin Na
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0209 industrial biotechnology ,Computer science ,State estimator ,020208 electrical & electronic engineering ,Real-time computing ,Cyber-physical system ,02 engineering and technology ,020901 industrial engineering & automation ,Control system ,0202 electrical engineering, electronic engineering, information engineering ,Observability ,Estimation methods ,Encoder ,Coding (social sciences) - Abstract
Designing control systems with a level of resilience against malicious attack has become an important problem because a number of attack incidents recently occurred resulted in significant damages. Resilient state estimation refers to a method of correctly estimating plant states in spite of attacks on sensors. The underlying principle for the majority of existing resilient state estimation methods is to take advantage of redundancies in sensing. More specifically, in order to tolerate (i.e., correctly estimate the plant states) attacks on up to $q$ sensors, the plant must satisfy 2q-redundant observability. In this work, we propose a sensor output coding based resilient state estimation that tolerates the same level of attacks but requires the plant to satisfy a relaxed condition of q-redundant observability. The coding based mechanism identifies the attacked sensors and invokes a state estimator that uses only intact sensors. This enables a correct state estimation even if more than half the sensors are corrupted, which is not possible in most existing works. To demonstrate the effectiveness of the proposed method, simulation results are presented.
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- 2019
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10. Dynamic Vehicular Route Guidance Using Traffic Prediction Information
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Jaegeun Park, Minseok Kwon, Yongsoon Eun, and Kwangsoo Kim
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050210 logistics & transportation ,Static routing ,Dynamic Source Routing ,Article Subject ,Computer Networks and Communications ,business.industry ,Computer science ,Equal-cost multi-path routing ,Routing table ,ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS ,05 social sciences ,Real-time computing ,020206 networking & telecommunications ,Geographic routing ,TK5101-6720 ,02 engineering and technology ,Computer Science Applications ,Link-state routing protocol ,0502 economics and business ,Multipath routing ,Telecommunication ,0202 electrical engineering, electronic engineering, information engineering ,Destination-Sequenced Distance Vector routing ,business ,Computer network - Abstract
We propose a dynamic vehicular routing algorithm with traffic prediction for improved routing performance. The primary idea of our algorithm is to use real-time as well as predictive traffic information provided by a central routing controller. In order to evaluate the performance, we develop a microtraffic simulator that provides road networks created from real maps, routing algorithms, and vehicles that travel from origins to destinations depending on traffic conditions. The performance is evaluated by newly defined metric that reveals travel time distributions more accurately than a commonly used metric of mean travel time. Our simulation results show that our dynamic routing algorithm with prediction outperforms both Static and Dynamic without prediction routing algorithms under various traffic conditions and road configurations. We also include traffic scenarios where not all vehicles comply with our dynamic routing with prediction strategy, and the results suggest that more than half the benefit of the new routing algorithm is realized even when only 30% of the vehicles comply.
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- 2016
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11. WiP Abstract: KRS-DGIST: A Resilient CPS Testbed for Radio-Based Train Control
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Yongsoon Eun, In-Hee Park, Jaegeun Park, Yuchang Won, Haegeon Jeong, Jeanseong Baik, Kyungtae Kang, Insup Lee, Kyung-Joon Park, and Buyeon Yu
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0209 industrial biotechnology ,business.industry ,Computer science ,Testbed ,Physical system ,Cyber-physical system ,020206 networking & telecommunications ,02 engineering and technology ,Telecommunications network ,020901 industrial engineering & automation ,Software ,Embedded system ,Control system ,0202 electrical engineering, electronic engineering, information engineering ,Train ,Architecture ,business - Abstract
This paper presents an architecture for cyber-physical systems resilient against external attacks and internal faults. The target CPS consists of multiple physical systems equipped with local embedded systems, a supervision module that oversees operations of the physical systems, and communication network connecting each physical system to the supervision module. We give an instantiation of the architecture on a radio-based train control system to demonstrate the resiliency under various safety critical scenarios. The testbed entitled KRS-DGIST includes a commercial train control and supervision software deployed in the Philippines. The railway installed sensors and other mechanisms are implemented reflecting the actual train control and supervision system, and the dynamics of the trains is computer simulated. Demonstrations are given with attacks on sensors, communication network, and embedded systems.
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- 2018
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12. Design and implementation of a mobile storage leveraging the DRAM interface
- Author
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Otae Bae, Jin-hyeok Choi, Yongmyung Lee, Sunmi Lee, Youngkwang Yoo, Nam Heehyun, Duckhyun Chang, Sungyong Seo, Youngjin Cho, Jaeheon Jeong, Jaegeun Park, Moon-sang Kwon, Seungdo Chae, and Sangyeun Cho
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010302 applied physics ,Mobile processor ,Computer science ,business.industry ,020206 networking & telecommunications ,02 engineering and technology ,Chip ,computer.software_genre ,01 natural sciences ,Software ,User experience design ,Embedded system ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Operating system ,Android (operating system) ,User interface ,business ,computer ,Dram ,Booting - Abstract
Storage I/O performance remains a key factor that determines the overall user experience of a computer system. This is especially true for mobile systems as users commonly browse and navigate through many high-quality pictures and video clips stored in their device. The appetite for more appealing user interface has continuously pushed the mobile storage interface speed up; emerging UFS 2.0 standard provisions a maximum bandwidth of as high as 1,200 MB/s. In this work, we propose, design, and implement a mobile storage architecture that leverages the high-speed DRAM interface for communication, thus substantially expanding the storage performance headroom. In order to effectively turn the existing DRAM interface into a storage interface, we design a new storage protocol that runs on top of the DRAM interface. Our protocol builds on a small host interface buffer structure mapped to the system's memory space. Based on this protocol, we develop and fabricate a storage controller chip that natively supports the LPDDR3 interface. We also develop a host software stack (Linux device driver and boot loader) and a host platform board. Finally we show the feasibility of our proposal by constructing a full Android system running on the developed storage device and platform. Our detailed evaluation shows that the proposed storage architecture has very low protocol handling overheads and compares favorably to a UFS 2.0 device. The proposed architecture obviates the need for implementing a separate host-side storage controller on a mobile CPU chip.
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- 2016
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13. Preparation of siloxane-silsesquioxane hybrid thin films for large-scale-integration interlayer dielectrics with excellent mechanical properties and low dielectric constants
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Sang Kook Mah, Jin-Heong Yim, Yi-Yeol Lyu, Hyun-Dam Jeong, Seok Chang, Jaegeun Park, Gwang Seok Kim, Jingyu Hyeon-Lee, and Jun-Hee Hahn
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chemistry.chemical_classification ,Spin coating ,Materials science ,Polymers and Plastics ,General Chemistry ,Polymer ,Dielectric ,Silane ,Silsesquioxane ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Siloxane ,Materials Chemistry ,Composite material ,Hybrid material ,Sol-gel - Abstract
Several kinds of homogeneous organic-inor- ganic hybrid polymer thin films were designed with im- proved mechanical properties and low dielectric constants (3.0). Novel soluble siloxane-silsesquioxane hybrid poly- mers were synthesized with cyclic and/or cage silane mono- mers, which had triorganosiloxy (R3Si1/2), diorganosiloxane (R2SiO2/2), and organosilsesquioxane (RSiO3/2) moieties with ethylene bridges at the molecular level, by the hydro- lysis and condensation of 2,4,6,8-tetramethyl-2,4,6,8-tetra(t- rimethoxysilylethyl)cyclotetrasiloxane (a cyclic monomer). The electrical properties of these films, including the dielec- tric constant (2.51), leakage current (6.4 10 11 A/cm 2 at 0.5 MV/cm), and breakdown voltage (5.4 MV/cm) were fairly good. Moreover, the mechanical properties of the hy- brid films, including the hardness (7 GPa), modulus (1.2 GPa), and crack-free thickness (2 m), were excellent in comparison with those of previous spin-on-glass materials with low dielectric constants. The excellent mechanical properties were proposed to be due to the high contents of SiOOH groups (30%) and the existence of ethylene bridge and siloxane moieties in the hybrid polymer precursors. In addition, the mechanical properties of the hybrid films were affected by the contents of the cagelike structures. The more cagelike structures a hybrid film contained, the worse its mechanical properties were. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 626 - 634, 2003
- Published
- 2003
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