About

Kwangmin Kim is an Associate Professor in the Department of History at the University of Colorado Boulder, specializing in the history of early modern China and East Asia. He teaches a variety of courses on Chinese and global history, including topics such as early modern China, Maritime Asia, China and Islam, and global capitalism and social inequality. Professor Kim received his Ph.D. from the University of California at Berkeley. His research focuses on the history of empire, borderlands, and transnational relations. He is the author of the book 'Borderland Capitalism: Turkestan Produce, Qing Silver, and the Birth of an Eastern Market,' published by Stanford in 2016. His other scholarly work includes articles and chapters on topics such as Qing conquest of Central Asia, Korean migration in Nineteenth-Century Manchuria, and Xinjiang under the Qing dynasty. Currently, Professor Kim conducts research on peasant resistances and gold mining in Manchuria from 1800 to 1911. He is accepting both M.A. and Ph.D. students.

Research topics

• Materials science
• Electrical engineering
• Composite material
• Mechanics
• Condensed matter physics
• Biology
• Chemistry
• Ecology
• Agronomy
• Botany
• Biochemistry
• Physics
• Food science

Selected publications

• Examining the Potential of Air Cargo Operations at Regional International Airports

  Journal of the Korean Society for Aviation and Aeronautics · 2025-03-01

  articleOpen accessSenior author

  The excessive concentration of air cargo transportation at Incheon International Airport has raised concerns about economic inefficiencies and the need for alternative airports in case of emergencies. This study investigates the necessity of diversifying air cargo functions and evaluates the feasibility of sharing these functions with Cheongju International Airport. The potential for activating air cargo at Cheongju Airport was examined from the perspectives of infrastructure, local government support policies, and regional air cargo demand. The results showed that Cheongju Airport has limited capacity for handling air cargo due to a lack of related infrastructure. However, based on the 2023 air cargo performance data, it was found that using Cheongju Airport could reduce inland logistics costs and transportation time by an average of about 40%. Furthermore, with the planned policy support from local governments in the Chungcheong region and the expansion of transportation networks, it is expected that Cheongju Airport can efficiently share air cargo demand once its infrastructure is expanded.

  PublisherOA PDFDOI

• Report on Over 25 000 Cycles Fatigue Test Results of a REBCO HTS Coil and Crossover Joint in a 7 T Background Magnetic Field at 4.2 K

  IEEE Transactions on Applied Superconductivity · 2025-02-04 · 1 citations

  article1st authorCorresponding

  This study presents experimental results on the fatigue characteristics of a REBCO coil and crossover joint, aiming to determine whether they can withstand cyclic loading up to the condition of the 40 T superconducting magnet's design fatigue limit. A pair of REBCO coils were wound with SP (SuperPower) 1013, using copper and stainless steel tape as co-winding materials. The crossover sample, designed to the 40 T superconducting magnet baseline specifications and composed of four Bi2223 (Sumitomo Type H) tape conductors soldered to a stainless steel foil, was mounted to the outermost turn of the REBCO coil. Both the coil and crossover were subjected to cyclic loading by ramping the current up and down in a 7 T background magnetic (BM) field at 4.2 K, with over 25,000 cycles applied. The electromagnetic strain between the outermost turn of the REBCO coil and the crossover joint was estimated numerically, considering the screening current distribution.

  PublisherDOI

• A Pulse Forming Network for Quench Protection of Superconducting Magnets

  IEEE Transactions on Applied Superconductivity · 2025-11-14

  articleSenior author

  The design and simulation of a Rayleigh line pulse forming network (PFN) is presented for active quench protection of superconducting magnets. In this context, the PFN is a ladder network of capacitors and inductors designed to deliver energy to quench heaters over a significantly longer period than a single capacitor or capacitor bank. The PFN is advantageous for protection of coils constructed with REBCO tape, which have a slow normal zone propagation speed and a high critical temperature. PFN's also have an inherent safety advantage over battery bank energy sources. The rise time of a typical Rayleigh network for this purpose can be on the order of 10-100 ms which is unacceptably slow compared to the timescale for thermal runaway during the onset of a quench. Thus, as a modification to the Rayleigh Line PFN, an extra stage consisting of a discharging capacitor with no accompanying inductor is added to achieve a nearly instant rise time. The advantages of this strategy are discussed, and the flexibility of the system is investigated when varying resistive loads, charge voltages, and component design.

  PublisherDOI

• Measured and Simulated Strain in the Large Scale Coil With Considering Winding Compressibility

  IEEE Transactions on Applied Superconductivity · 2025-11-10 · 1 citations

  article

  The Large Scale Coil (LSC) is a high-temperature superconducting (HTS) coil that has been developed and tested in the research and development efforts for the 40-T All-Superconducting Magnet Project at the National High Magnetic Field Laboratory (NHMFL). The LSC is composed of stacked pancake disks consisting of 2-in-hand wound rare-earth barium copper oxide coated conductor (CC REBCO) tapes with stainless steel and copper co-wind. Under high magnetic fields, Lorentz forces on the REBCO tapes can impact the performance of the coil. Experimental strain data was collected and compared to simulated results. Initial results reveal significantly higher simulated strain at both inboard and outboard gauges. Manufactured REBCO have thickness variations along tape width. Similarly, stainless steel tapes used for over-banding have microscopic surface asperities. These tapes were initially assumed to be perfectly flat and had a “hard contact” condition in simulations. Comparison of experimental results to simulations reveal that incorporating these aspects of REBCO tape surface structure decreases the difference between simulated and experimental results for particular cases. In addition, edge friction effects due to “axial clamping” were simulated, and resulting strain was compared to experimental data. Strain data from the LSC tests are a valuable resource for verification of modeling methods and improving our understanding and design of large and complex HTS magnets such as the 40-T. This investigation compares measured strain data with simulated strain to assess and improve our current modeling techniques for HTS coil design.

  PublisherDOI

• Design Construction and Operation of a Conduction Cooling-Type HTS Module Testing System

  IEEE Transactions on Applied Superconductivity · 2025-10-17

  article1st authorCorresponding

  This paper describes the design, construction, and test results of the conduction cooling-type HTS module testing system. The constructed conduction cooling-type HTS module testing system uses two two-stage GM cryo-coolers as the primary cooling source. The 1st stage cold head of the cryo-cooler is responsible for cooling the metal current leads and radiation shields, and the bottom side of the HTS leads. The 2nd stage temperature section is responsible for cooling the Oxygen Free Copper (OFCu) cooling plate and top-side of the HTS leads. The HTS test module is cooled through the OFCu cooling plate. The HTS module testing system controls the temperature of the HTS module under testing from 4 K to 30 K and can supply an operating current of up to 800 A. All operating parameters of the HTS module test system are controlled and recorded using a Data Acquisition (DAQ) system based on LabVIEW.

  PublisherDOI

• Harmonic errors of a 9.4 T all-REBCO NMR magnet affected by screening current and geometric inconsistency of coated conductors

  Scientific Reports · 2024-08-19 · 3 citations

  articleOpen access

  REBa $$_2$$ Cu $$_3$$ O $$_{7-\text {x}}$$ (REBCO, RE = rare earth)-coated conductor is a competitive option in terms of current-carrying capacity and high-stress durability in developing high-field magnets for nuclear magnetic resonance (NMR) research. Meanwhile, a technical challenge in utilizing a stand-alone REBCO NMR magnet is an unexpected difference in the field uniformity between the designed and measured values after being constructed and charged, i.e., harmonic errors. Bortot et al., and Li et al., reported analytic evidence of the related issue. However, sufficient research has not yet been conducted, so evidence should be supplemented further. Here we report harmonic errors due to screening current and inconsistent conductor thickness, confirmed by a 400 MHz 1H NMR magnet development project. The magnet was first charged up to its operating current, and then multiple overcharge-discharge cycles were applied, which was an empirically optimized operation protocol. A field mapping device obtained magnetic fields at designated locations in the room-temperature bore. The result showed over 100 ppm field uniformity difference between designed and measured values. A simulation model was developed considering screening current and inconsistent conductor thickness for reproducing the field distribution. Comparison of voltages and fields between simulation and measurement validated the model. Further analysis of the overcharge-discharge effect on harmonic errors demonstrated that even and odd-order harmonics are mainly attributed to screening current and geometric inconsistency while confirming the limitation of the screening current mitigation effect. Hence, we concluded that the desirable requirement of the sub-ppm level field uniformity generation might be barely possible with the current REBCO NMR magnet design approach.

  PublisherOA PDFDOI

• Comparison Between Results of Quench Simulation and Tests of a 13 T REBCO Coil in a Strong Background Magnetic Field

  IEEE Transactions on Applied Superconductivity · 2024-02-06 · 3 citations

  article

  In the framework of the 40 T all-superconducting magnet project at the National High Magnetic Field laboratory, improvements have been made in a quench model and the quench code that has been constructed to simulate the behavior of a magnet consisting of an HTS inner coil set with an LTS background field. The quench model, initially developed for the NHMFL 32 T magnet project, incorporates additional details of the REBCO conductor on a localized level. These include nonuniform magnetic field distribution across each conductor turn and deformation of the turns due to screening currents which affects the true field angle applied to the conductor's a-b plane. Detailed measurements of the test coil's conductors have also been made to improve the simulations. These include the slope of the a-b plane using X-ray techniques and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_C (B, θ, T)</i> of each conductor length using torque magnetometry. The test coil generating a field up to 13 T is an insulated, two-in-hand REBCO coil with twelve modules. Deliberate quench tests were performed with it in self-field and with a 11.4 T background field. The results and discussion of the comparisons are presented.

  PublisherDOI

• Author Correction: Harmonic errors of a 9.4 T all-REBCO NMR magnet affected by screening current and geometric inconsistency of coated conductors

  Scientific Reports · 2024-10-15 · 4 citations

  erratumOpen access
  PublisherOA PDFDOI

• Combined Axial Pressure and Screening Current Induced Stress Test on REBCO Pancake Coils

  IEEE Transactions on Applied Superconductivity · 2024-12-23 · 1 citations

  article

  Screening current induced stress (SCIS) causes conical deformation in REBCO pancake coils. In an actual ultra-high field magnet, a REBCO pancake coil is subjected to axial pressure from upper pancake coils, in addition to SCIS. This axial pressure likely enhances the conical deformation and hoop strain. In this study, we developed a test scheme, referred to as the combined axial pressure and tape tilting (CATT) test, to investigate the degree of strain enhancement caused by axial pressure. As a result of the test, a 50% increase of hoop strain was observed at an axial load of 180 kN, leading to yielding of the REBCO tapes. Buckling deformation due to compressive hoop strain was also observed during the charging test with current in negative direction under a background field.

  PublisherDOI

• Asymmetrical Elongation of Branched Alkyl Chains in Non‐Fullerene Acceptors for Large‐Area Organic Solar Modules

  Advanced Functional Materials · 2024-07-18 · 9 citations

  article

  Abstract With the drive toward the development of large‐area organic solar cells (OSCs), there is a critical need for advanced fabrication techniques that ensure both their efficiency and scalability. In particular, a shift from toxic halogenated solvents to safer non‐halogenated alternatives such as o ‐xylene, which have lower environmental and health impacts, is required. However, transitioning to non‐halogenated solvents can lead to serious problems, including aggregation within the active layer, which compromises film morphology and the resulting efficiency of OSCs. To address this aggregation, in the present study, the 2‐ethylhexyl (EH) groups in L8‐BO(EH‐EH) are replaced with longer chains (2‐heptylundecyl [HU], 2‐decyltetradecyl [DT], and 2‐dodecylhexadecyl [DH] groups) to synthesize the non‐fullerene acceptors (NFAs) of L8‐BO(HU‐HU), L8‐BO(HU‐DT), and L8‐BO(HU‐DH). The NFAs with the longer alkyl chains are highly soluble in o ‐xylene and produce highly uniform films, making them more suitable for use in large‐area OSCs. Using the NFAs, slot‐die‐coated organic solar modules with an active area of 200 cm 2 are fabricated; the L8‐BO(HU‐DT)‐based module exhibits an impressive power conversion efficiency of 11.44%. This work thus underscores the asymmetrical elongation of alkyl chains in the NFAs to mitigate severe NFA phase separation and improve film printability in the practical production of organic solar modules.

  PublisherDOI

Frequent coauthors

• Seungyong Hahn

  Seoul National University

  44 shared

• In-Keun Yu

  Changwon National University

  37 shared

• Seokho Kim

  Changwon National University

  37 shared

• Minwon Park

  Changwon National University

  36 shared

• D. C. Larbalestier

  Florida State University

  26 shared

• So Noguchi

  Hokkaido University

  24 shared

• Kabindra R. Bhattarai

  National High Magnetic Field Laboratory

  19 shared

• Gyeong-Hun Kim

  Korea Electrotechnology Research Institute

  18 shared

Education

• Ph.D.

  University of California at Berkeley