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Choah Shin

Graduate science fellowship supports interdisciplinary mathematics and energy research

By Srila Nayak

OSU mathematics Ph.D. student Choah Shin (right) with mathematicians Malgorzata Peszynska and Azhar Alhammali (left)

The 2019-2020 Larry Martin and Joyce B. O’Neill Fellowship was awarded to fifth-year mathematics Ph.D. student Choah Shin. The award supports her research on the theoretical and applied aspects of modeling processes associated with the sub-sea sediments of methane hydrate, an energy resource with documented impact on the climate. The fellowship, endowed by Larry Martin and his wife Joyce O’Neill, recognizes students who demonstrate high achievement and whose research involves computational modeling.

The competitive award, designated for graduate students in the College of Science, provides full tuition with an annual stipend of $25,000. Larry Martin (B.S., ’59) is a mathematics and engineering alumnus who had a successful career as a mathematician focusing on modeling for companies such as Lockheed Martin and IBM. After a successful career at IBM, he created, bought and invested in companies, sometimes running them but most often focusing on software and consulting. Martin was the owner of Troon Vineyard in southern Oregon's Applegate Valley which he sold in 2017.

The O’Neill Fellowship acknowledges Shin’s numerous research accomplishments. Her advisor, mathematics professor Malgorzata Peszynska, praises Shin for making “incredible progress on her path towards becoming a computational scientist” and developing “an independent critical viewpoint of computational science” that is responsive to mathematical analysis and the relations between mathematics and “important real-world applications.”

Shin’s broad research experiences span several sub-projects involving simulations for environmental and energy applications. These projects have landed her two prestigious internships in national labs and resulted in more than 20 research presentations comprising posters, invited talks and seminar presentations regionally and internationally. Always passionate about mathematics, Shin is steadily building a career in the field.

Her family moved to Chicago from Daejeon in South Korea just before Shin entered ninth grade. Thanks to her advanced mathematical skills honed by the Korean education system, Shin was placed in upper-level mathematics classes with juniors and seniors in her high school. “That math class was also easy for me. Although I had difficulties with the English language for the first few years,” remarked Shin.

After completing high school, she enrolled at the University of Illinois at Chicago to study mathematics. There she received a B.S. in mathematics (Honors with Distinction) and a M.S. in energy engineering. Shin applied to the Ph.D. program in mathematics at Oregon State University after discovering Peszynska’s research, which, to her delight, lined up perfectly with her own interests in mathematics and energy.

New frontiers in energy research

Methane hydrate — frozen deposits of natural gas in the sea’s subsurface sediment — found primarily in the Arctic and Antarctica is a double-edged fuel source. When the ice-like methane hydrate deposits melt due to high temperatures or drilling, large volumes of methane gas are produced that escape into the atmosphere. While methane hydrate deposits are viewed as one of the largest sources of natural gas and a viable fossil fuel, methane emissions contribute to global warming and climate change. Moreover, converting hydrate compounds into gas can be risky or unstable, making large-scale extraction or production of this powerful greenhouse gas difficult.

Shin’s mathematical models and theoretical approaches tackle various challenges with respect to methane gas transport and flow through different layers in sub-ocean sediments. Various mechanisms of methane transport depend on how hydrate crystals are deposited between the grains of porous medium; to this aim, Shin implemented a Stokes flow model that works at the micro-scale or pore-level events of gas displacement and movement. Overall, theoretical and practical aspects of Shin’s work contribute to a deeper understanding of the impact of hydrate on the environment.

Methane gas transport model

Simulation of methane gas transport in a heterogeneous domain above BHSZ (bottom of hydrate stability zone) with the formation of methane hydrate depicted by spikes of the red curve. The data for this problem is synthetic but resembles typical layers found in subocean sediments; the background color corresponds to the different types of sediment, and the dotted blue curve shows the maximum solubility which depends on the (hypothetical) type of sediment. The solid blue curve shows the amount of methane dissolved in the liquid phase, which must not exceed the dotted curve. When hydrate forms (and red spikes form), the solubility must equal the maximum solubility. The challenges in the simulation are to account for this constraint as well as to represent the spikes accurately (Illustration by Choah Shin).

“Methane is going to be the next energy source for our planet. I am hoping my research will help prevent some environmental issues with methane when it is exposed to air,” said Shin. “I enjoy my research because it is interdisciplinary in nature and combines my interests in mathematics and energy engineering.”

Shin’s growing expertise with varied modeling concepts landed her an internship in summer 2018 with the Pacific Northwest National Laboratory (PNNL) in Richland, Washington. There she worked on developing mathematical models for phase equilibria for a mixture of methane, nitrogen and oxygen in the PNNL lab of Mark White, the lead researcher on an international comparison study of different hydrate models.

Pores generated with glass beads

Stokes flow in 2D porescale geometry simulated with Choah’s code. Shown are porous grains (white) and the flow velocity magnitude (in color). This simulation can be coupled to methane transport or to biofilm growth which change the flow paths when new semi-permeable solids form in the originally void space available to the flow. (Figure supplied by Choah Shin).

The following year, she was selected as one of the recipients of an NSF Mathematical Sciences Graduate Internship that took her to the National Renewal Energy Laboratory (NREL) at Golden, Colorado. According to Peszynska, Shin’s lab mentor at the NREL designed a project to specifically take advantage of her unique capabilities mixing computational mathematics with her passion for renewable energy resources plus experience with fluids modeling.

Choah’s summer project involved setting up computational solvers (a piece of mathematical software that solves a problem) for simulations of cryogenic helium in the supercritical phase for cooling mechanisms in a range of applications, including quantum computers, superconducting magnets and infrared sensors used in astronomical measurements. Since completing her project, Shin has presented her work at research conferences and is at work on a publication.

“The NREL internship was very helpful for enhancing my programming skills. Although I have done a lot of computational mathematics, the internship gave me the chance to work on supercomputers and with several different languages such as Python, Fortran and C++. I loved it!” Shin said.

Having enjoyed research in national labs immensely, Shin would like to take up a postdoctoral position at a national lab after completing her Ph.D. this year.

“I love doing research, and at the labs I was able to 100 percent focus on my research. I love the possibilities of what I can do in a lab,” mentioned Shin.

In addition to programming experiences, Shin’s internships also broadened her networking and science communications skills and introduced her to influential communities of scientists and collaborators.