Conceptual design study of a superconducting spherical tokamak reactor with a self-consistent system analysis code
B.G. Hong, Y. S. Hwang, Junsu Kang, D.W. Lee, Han Gyu Joo, M. Ono
IF 4
Nuclear Fusion
In a spherical tokamak (ST) reactor, the radial build of toroidal field coil and the shield play a key role in determining the size of the reactor. For self-consistent determination of the reactor components and physics parameters, a system analysis code is coupled with a one-dimensional radiation transport code. A conceptual design study of a compact superconducting ST reactor with an aspect ratio of up to 2.0 is conducted and the optimum radial build is identified. It is shown that the use of an improved shielding material and high-temperature superconducting magnets with high critical current density opens up the possibility of a fusion power plant with compact size and small re-circulating power simultaneously at a low aspect ratio, and that by using an inboard neutron reflector instead of a breeding blanket, tritium self-sufficiency is possible with an outboard blanket only and thus a compact-sized all superconducting coil ST reactor is viable.
Conceptual design study of a superconducting spherical tokamak reactor with a self-consistent system analysis code
B.G. Hong, Y. S. Hwang, Junsu Kang, D.W. Lee, Han Gyu Joo, M. Ono
IF 4
Nuclear Fusion
In a spherical tokamak (ST) reactor, the radial build of toroidal field coil and the shield play a key role in determining the size of the reactor. For self-consistent determination of the reactor components and physics parameters, a system analysis code is coupled with a one-dimensional radiation transport code. A conceptual design study of a compact superconducting ST reactor with an aspect ratio of up to 2.0 is conducted and the optimum radial build is identified. It is shown that the use of an improved shielding material and high-temperature superconducting magnets with high critical current density opens up the possibility of a fusion power plant with compact size and small re-circulating power simultaneously at a low aspect ratio, and that by using an inboard neutron reflector instead of a breeding blanket, tritium self-sufficiency is possible with an outboard blanket only and thus a compact-sized all superconducting coil ST reactor is viable.
Changes in Institutional Logic in the Era of Local Extinction: Focusing on the Diffusion and Termination of Ordinances Supporting International Marriages for Rural Bachelors
Han Gyu Joo, M. Jeon
Korean Journal of Public Administration
본 연구는 한국의 저출산과 고령화로 인한 지방소멸 위기에 대응하는 목적으로 도입된 ‘농촌총각 국제결혼 지원조례’의 제정과 폐지에 제도적 논리의 변화가 미치는 영향을 규명하고자 한다. 2005년부터 2023년까지 226개의 기초자치단체를 패널데이터를 구축하여, 사건사 분석 구간별 지수모델(EHPA, event history analysis Piecewise Exponential Model)을 실시하였다. 실증분석 결과, 조례 제정에는 도구적 논리의 하위 요인 중 지역의 총 혼인 수가 부정적인 영향을 미쳤으며, 여성에 비해 남성인구가 많을수록 조례 가능성이 증가했다. 한편, 규범적 논리의 하위 요인으로 해당 지역의 인권 관련 조례의 수, 외국인 수는 통계적으로 유의미한 수준에서 조레 폐지의 가능성을 높였다. 이러한 결과는 정책 변화의 시간성과 맥락을 고려한 분석이 필요하며 구체적으로 지방정부의 단기적인 인구정책 효과에 치우친 기능주의적 접근은 정책의 장기적 수용성과 정당성을 약화시킬 수 있으므로 보다 섬세한 정책설계가 필요함을 시사한다.
Tracing the Formation History of Intrahalo Light with Horizon Run 5
Han Gyu Joo, M. James Jee, Juhan Kim, Jaehyun Lee, Jongwan Ko, Changbom Park, Jung-Hun Shin, Owain Snaith, Christophe Pichon, B. K. Gibson, Yonghwi Kim
arXiv (Cornell University)
We investigate the formation history of intrahalo light (IHL) using the high-resolution (~1 kpc), large-scale (~Gpc) cosmological hydrodynamical simulation, Horizon Run 5 (HR5). IHL particles are identified by carefully considering both their binding energies and positions with respect to the tidal radii of individual galaxies. By analyzing more than 1,200 galaxy groups and clusters with $\geq 10^{13} M_{\odot}$ and tracing their individual IHL particles back in time, we classify the origin of each IHL particle at each epoch based on the status of the originating galaxy into three categories: brightest halo galaxy (BHG) formation/merger, satellite galaxy stripping, and pre-processing. Our study reveals that the IHL production through BHG formation/merger is the predominant production channel, contributing over 60\% of the total IHL mass across all redshifts. The second most significant IHL production channel is pre-processing, providing more than 20\% in the final HR5 snapshot. Stripping is negligible at $z>4$ but becomes gradually more important as halos mature at $z<4$. Finally, we verify that IHL production through the disruption of dwarf galaxies and in-situ formation is negligible, contributing less than ~3\% and ~0.5\% to the total IHL production, respectively.
Multiphysics Analysis System for Heat Pipe–Cooled Micro Reactors Employing PRAGMA-OpenFOAM-ANLHTP
Jaeuk Im, Myung Jin Jeong, Namjae Choi, Kyung Min Kim, Hyoung Kyu Cho, Han Gyu Joo
IF 1.3
Nuclear Science and Engineering
A multiphysics analysis system for neutronics/thermomechanical/heat pipe thermal analysis of heat pipe–cooled micro reactors was developed using the PRAGMA code as the neutronics engine. PRAGMA, which was developed as a graphics processing unit (GPU)-based continuous-energy Monte Carlo code for power reactor applications, now has an extended geometry package to handle geometries with unstructured meshes generated by Coreform Cubit. The NVIDIA ray-tracing engine OptiX has been exploited for efficient neutron transport on unstructured mesh geometry. On the multiphysics side, the open-source computational fluid dynamics tool OpenFOAM and one-dimensional heat pipe analysis code ANLHTP have been adopted. The manager-worker system based on the message passing interface dynamic process management model enables efficient coupling of codes employing different parallelization schemes. With all the features, the multiphysics analysis of the 60-deg symmetrical sector model of the MegaPower three-dimensional core was performed for normal operation and heat pipe–failed conditions. The multiphysics coupling run time was about 2.5 h, in which the Monte Carlo simulation employing more than 10 billion histories was performed within half an hour on a single rack of computing nodes mounted with 24 NVIDIA Quadro GPUs. Accordingly, this demonstrates the soundness and robustness of the tightly coupled three-way multiphysics analysis system.
