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Composite Layer Design Using Classical Laminate Theory for High Pressure Hydrogen Vessel (Type 4)
Gunyoung Park,Chul Kim 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4
As air pollution becomes more severe, the use of clean energy in vehicles is an inevitable requirement and it is leading the development of automotive industries. Especially, hydrogen-fueled vehicles require safe and lightweight high pressure storage vessels to carry enough amounts of hydrogen gas. To develop mechanically robust and lightweight high pressure vessel, it is of significance to establish design and manufacturing process for liners and carbon fiber reinforced plastics layers. In this study, to design a composite layer in a high pressure hydrogen vessel (Type 4), a calculation method of stress generated in each ply by applying the CLT (Classical Laminate Theory) is proposed. And based on the calculation method, we carried out the composite layer design in the hydrogen high pressure vessel (Type 4) that can satisfy the requirement for lightweightness and designed the thickness and the pattern of the composite layer with more accuracy than the netting theory and with more rapid than FEA.
Design of composite layer and liner for structure safety of hydrogen pressure vessel (type 4)
Gunyoung Park,Hyoseong Jang,김철 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8
Due to the problems of fossil fuel exhaustion and environmental pollution, the use of hydrogen fuel has been increasing gradually, so there is also need of commercialization of hydrogen fuel cell vehicle. In order to increase its fuel efficiency, light-weightning and structural design, which are to optimize thickness and shape of the pressure vessel (end closure and boss) and winding angle of composite, have been required. This study has carried out as follows to obtain structural safety of hydrogen pressure vessel (type 4) under working pressure (700 bar). Plastic liner was designed using dome shape with isotensoid curve and spherical shape not to slip in the dome region while filament winding. After calculating the initial thickness of composite by netting theory, the composite thickness in both cylinder and dome parts to satisfy structural safety were obtained by FEM, changing the thicknesses calculated from theory. Also, optimal design of aluminium boss shape was performed using the response surface method to achieve light-weightning and increase of inner capacity. Based on the above results, structural safety of the optimal hydrogen pressure vessel (type 4) with the composite layer and boss shape finally determined was verified through FEA.
Overview of recent progress in 3D field physics in KSTAR
Park Gunyoung,In Yongkyoon,Park Jong-Kyu,Ko Won-Ha,Lee Jaehyun,Kim Minwoo,Shin Giwook,Hahn Sang-Hee,Kim SangKyeun,Yang Seong Moo,Hu Qiming,Rhee Tongnyeol,Choi Minjun J.,Kim Kimin,Lee Hyung-Ho,Jeon You 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.8
Various 3D field physics challenges of magnetically confined plasmas arise when the driving source comes from either externally applied non-axisymmetric 3D magnetic perturbations or plasma instabilities inside the plasma. Recently, several key outstanding topics of 3D field physics have been extensively studied in the Korean Superconducting Tokamak Advanced Research (KSTAR), such as edge-localized-mode (ELM) control by resonant magnetic perturbation (RMP), error field (EF) control, 3D field effects on rotation and transport, and RMP-induced alteration of divertor heat flux and detachment. KSTAR has a few physically unique features (i.e., high rotation and long-pulse plasmas with a low intrinsic EF) and machine/diagnostic capabilities (i.e., 3-row in-vessel control coil and state-of-the-art 2D/3D imaging diagnostics), which have been taken advantage of until now to address critical 3D field physics issues relevant to ITER and K-DEMO. Among many remarkable achievements are the robust access to and control of n = 1 RMP ELM suppression, along with a development of its physics basis tools, parameter expansion, optimization, and long-pulse control techniques. Nonetheless, a series of unresolved 3D physics themes, as well as limited coverage of 3D field operating regimes, have also been identified as future works for the 3D field research in KSTAR. In this paper, we provide an overview about the recent progress of KSTAR 3D field physics and present future plans of KSTAR 3D research toward a future fusion reactor.
3D field phase-space control in tokamak plasmas
Park, Jong-Kyu,Jeon, YoungMu,In, Yongkyoon,Ahn, Joon-Wook,Nazikian, Raffi,Park, Gunyoung,Kim, Jaehyun,Lee, HyungHo,Ko, WonHa,Kim, Hyun-Seok,Logan, Nikolas C.,Wang, Zhirui,Feibush, Eliot A.,Menard, Jon NATURE PUBLISHING GROUP 2018 NATURE PHYSICS Vol.14 No.12
Analysis of Forming Factors for Build-Up Phenomenon in High Pressure Hydrogen Vessel
Gunyoung Park,Rivaldo Mersis Brilianto,Hyoseo Kwak,Chul Kim 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.3
The development of hydrogen charging stations is continuously progressing and is focusing on hydrogen pressure vessels (type 1), which are one of the components of a hydrogen filling station. The dome part of a hydrogen pressure vessel is formed by a spinning process using a pipe that is manufactured by a hot forging method. For thick pipes, there is a problem with non-uniform formation of the dome part. Since this problem causes the boss part not to form, it is difficult to obtain the desired thickness of the boss part for attaching a valve, which may affect the structural safety of the dome part. In this study, a finite element analysis (FEA) model of the spinning process was established for a thick pipe, and the validity of the analysis was compared with the result of the actual process. Furthermore, the causes of forming defects during the spinning process were reviewed through FEA by applying various design parameters. Based on the results, design factors were selected to control the forming defects in the spinning process, and a spinning process was designed to minimize the thickness change of the dome part.
무선 네트워크에서 재전송 손실 복구를 통한 TCP SACK 성능 향상 방안
박건영(Gunyoung Park),김범준(Beomjoon Kim),김동민(Dongmin Kim),한제찬(Jechan Han),이재용(Jaiyong Lee) 한국정보과학회 2005 정보과학회논문지 : 정보통신 Vol.32 No.3
무선 전송 기술이 발전함에 따라 현재 유선 네트워크에서 주로 동작하는 인터넷은 무선 환경으로 확장되어 가고 있다. 인터넷의 주요 수송 계층 프로토콜인 TCP(transmission control protocol)는 신뢰성이 높은 유선 네트워크상에서 동작한다는 가정 하에 설계되고 개발되었다. 그러나 무선 환경에서는 패킷 손실이 망의 혼잡(network congestion)에 의해서뿐만 아니라 전송 과정에서의 물리적인 현상에 의한 에러에 의해 발생할 수 있고, 이로 인해 발생하는 비 혼잡 패킷 손실(non-congestion packet loss)에 의해서 TCP의 성능은 크게 저하될 수 있다. 전반적인 TCP의 처리율(throughput)은 재전송 타임아웃 (retransmission timeout)의 발생 빈도에 의해 큰 영향을 받기 때문에 이를 해결하기 위한 많은 연구가 진행되어 왔다. 그러나 재전송된 패킷 손실(lost retransmission)로 인한 재전송 타임아웃은 여전히 해결되지 못한 상태이다. 따라서 본 논문에서는 재전송 손실을 감지하고 이를 복구할 수 있는 간단한 알고리듬을 제안한다. 제안된 알고리듬의 성능을 분석하기 위해서 무선 환경에서 발생하는 두 가지 형태의 패킷손실 모델에 대한 시뮬레이션을 수행하였다. 시뮬레이션 결과를 통해서 제안된 알고리듬이 손실 복구 차원에서 TCP의 성능을 상당히 향상시킴을 보인다. As today's networks evolve towards an IP-based integrated network, the role of transmission control protocol(TCP) has been increasing as well. As a well-known issue, the performance of TCP is affected by its loss recovery mechanism that is comprised of two algorithms; fast retransmit and fast recovery. Although retransmission timeout(RTO) caused by multiple packet losses can be avoided by using selective acknowledgement(SACK) option, RTO cannot be avoided if a retransmitted packet is lost. Therefore, we propose a simple modification to make it possible for a TCP sender using SACK option to detect a lost retransmission. In order to evaluate the proposed algorithm, simulations have been performed for two scenarios where packet losses are random and correlated. Simulation results show that the proposed algorithm can improve TCP performance significantly.
Diameter 프로토콜에서의 실시간 Accounting 기법
박건영(Gunyoung Park),김기천(Keecheon Kim) 한국정보과학회 2003 한국정보과학회 학술발표논문집 Vol.30 No.2Ⅲ
AAA 프로토콜중에 하나인 DIAMETER으 기능과 특성에 대해서 알아보고 유무선의 다양한 환경에서 신뢰할 수 있는 실시간 Accounting을 할 수 있도록 하기 위해 기존의 Accounting의 문제점을 보완한 Accounting 모델에 대해 알아 보도록 한다.