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Your search keyword '"Kim, Daewook"' showing total 187 results
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187 results on '"Kim, Daewook"'

1. Development of a data reduction pipeline for the Aspera SmallSat mission

Author

Ibsen, Jorge, Chiozzi, Gianluca, Keppler, Miriam, Chung, Haeun, Khan, Aafaque R., Hergenrother, Carl W., Vargas, Carlos, Chambers, Jacob, Vider, Jacob, Selznick, Sanford, Ghidoli, Giulia, Tanquary, Hannah, Hamden, Erika, Howk, J. Christopher, Agarwal, Simran, Augustin, Ramona, Behroozi, Peter, Burchett, Joe, Choi, Heejoo, Corlies, Lauren, Corliss, Jason, Coronado, Fernando, Davis, Greyson, Dettmar, Ralf-Jürgen, Douglas, Ewan, Garcia, Elijah, Goodwin, Alfred, Hamara, Dave, Harris, Walt, Hoadley, Keri, Kidd, John, Kim, Daewook, Li, Jessica, McMahon, Tom, Melso, Nicole, Noenickx, Jamison, Noriega, Gabe, Pecha, Ryan, Sauve, Cork, Schiminovich, David, Oswald, Siegmund, Truong, Daniel, Uppnor, Sumedha, Verts, Bill, Wollcott, Ellie, Yescas, Naomi, Zaritsky, Dennis, Bradley, Harrison, and Brendel, Trenton

Published
2024
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11. Approaches to lowering the cost of large space telescopes

Author

Hull, Tony B., Kim, Daewook, Hallibert, Pascal, Douglas, Ewan S., Aldering, Greg, Allan, Greg W., Anche, Ramya, Angel, Roger, Ard, Cameron C., Chakrabarti, Supriya, Close, Laird M., Derby, Kevin, Edelstein, Jerry, Ford, John, Gersh-Range, Jessica, Haffert, Sebastiaan Y., Ingraham, Patrick J., Kang, Hyukmo, Kelly, Douglas M., Kim, Daewook, Lesser, Michael, Leisenring, Jarron M., Lin, Yu-Chia, Males, Jared R., Martin, Buddy, Payan, Bianca Alondra, P. M., Sai Krishanth, Rubin, David, Selznick, Sanford, Van Gorkom, Kyle, Jannuzi, Buell T., and Perlmutter, Saul

Published
2023
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12. Simultaneous and Continuous Production of Carbon Nanotubes and Hydrogen by Catalytic CH4Decomposition in a Pressurized Fluidized-Bed Reactor

Author

Bae, Keon, Kim, Daewook, Dung, Pham Anh, Lee, Doyeon, Hwang, Byungwook, Go, Kang Seok, Kim, Woohyun, Lee, Jun Kyu, Im, Ji Sun, Kang, Seok Chang, and Lee, Soo Hong

Abstract

The optimal operating conditions for a fluidized-bed reactor (FBR) capable of simultaneous and continuous production of both hydrogen and carbon materials via direct decomposition of methane, employing a transition-metal-based catalyst, were determined. The nickel-based catalyst was synthesized via the sol–gel method and the catalyst particles, classified as Geldart group B, were used in the FBR. As the first step, the optimal reaction temperature and flow rate for the catalysis were determined by using a lab-scale FBR with an internal diameter of 28 mm. Using the data obtained in the lab-scale FBR experiments, the appropriate operating conditions were established for a bench-scale FBR with an internal diameter of 76.2 mm. The system was operated in a continuous manner, in which hydrogen and solid carbon with catalyst particles were simultaneously and continuously discharged and the catalyst was periodically fed into the reactor. Approximately 5 h stable operation and performance were confirmed at an average temperature of 710 °C and a pressure of 2 bar in the fluidized bed. The maximum carbon production rate observed was 5 kg/day, and the hydrogen production rate was 1.66 kg/day with the bench-scale reactor. The quality of the carbon products, in the form of multiwalled carbon nanotubes, was characterized and evaluated using transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy.

Published
2024
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14. Sustainability of social economy organizations (SEOs): An analysis of the conditions for surviving and thriving

Author

Kim, Daewook, Cho, Wonhyuk, and Allen, Barbara

Abstract

ABSTRACTSocial economy organizations (SEOs), designed to do good for society, have been attracting significant attention as an alternative to purely profit-driven businesses. However, the sustainability of these hybrid organizations has been questioned due to the challenges in meeting the dual bottom-lines of financial performance and social purpose. This article takes a causal-process tracing (CPT) case study approach and analyzes eight SEOs to investigate the common characteristics of sustainable SEOs. The results of the analysis show that effective leadership is a sufficient (but not necessary) condition for the survival of SEOs, while leadership is a necessary (but not sufficient) condition for SEOs’ thriving. Business competitiveness is found to be necessary for SEOs’ long-term success and performance over time. Collaborative networking is a contributory condition for SEOs thriving but not a necessary condition for their survival.

Published
2024
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15. 54‐1: Development of UDC Image Restoration Technology Using Space Variant CNN

Author

Kim, Daewook, Cho, Jaebum, Yoo, Jewon, Hwang, Hyunjoo, Park, Sungjae, Baek, Seungin, and Cho, Sungchan

Abstract

With the continuous evolution of mobile device technologies, the integration of under‐display cameras has emerged as a groundbreaking innovation in the pursuit of bezel‐less and immersive visual experiences. As this technology becomes increasingly prevalent, it introduces a unique set of challenges, particularly in the realm of photography. In particular, the flare cannot be restored by conventional image processing due to saturated pixels. Therefore, a deep learning network capable of restoring such deterioration is proposed. The network is trained by a synthetic datasets generated by accurate optical simulation. However, the distortion of the camera lens distorts the shape of flare differently depending on its position in the photo, and it degrades restore quality. In this paper, we propose space‐variant CNN for solving distortion problem.

Published
2024
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22. MOIS: a configurable slit multi-object infrared spectrograph

Author

Hull, Tony B., Kim, Daewook, Hallibert, Pascal, Surya, A., Puravankara, M., Mookerjea, B., Poojary, S., D. Costa, S. L. A., Narang, M., Madhwani, P. P., Kutty, A. P. K., Bhagat, S. B., Shah, H., Banerjee, B., Gharat, S., Jadhav, R., Kurhade, V. N., Parmar, J. V., and Tyagi, H.

Published
2023
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26. Understanding the role of additive manufacturing in the development of astronomical hardware

Author

Hull, Tony B., Kim, Daewook, Hallibert, Pascal, Atkins, Carolyn, Chahid, Younes, Wells, James T., Westsik, Marcell, Morris, Katherine, Breen, Ciarán, Macleod, Alastair, Bissell, Lawrence, Cochrane, William, Kotlewski, Richard, McPhee, Scott, Snell, Robert M., Todd, Iain, Beardsley, Mat, Harris, Michael, Pimentel, Misael, McKegney, Scott, Orr, Jonathan, Alcock, Simon G., Nistea, Ioana Theodora, Cottarelli, Simone, and Tammas-Williams, Samuel

Published
2023
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33. Initial testing of a MODE lens telescope

Author

Kim, Daewook, Choi, Heejoo, Ottevaere, Heidi, Rascher, Rolf, Kim, Youngsik, Esparza, Marcos, Wang, Zichan, Brar, Nicholas, Zhang, Yingying, Kim, Daewook, Choi, Heejoo, Apai, Daniel, Fellows, Chuck, Yi, Allen, Cai, Yuxin, Kim, Geonhee, Choi, Hwanjin, Yeo, Woojong, and Milster, Tom D.

Published
2022
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40. Computer-controlled finishing via dynamically constraint position-velocity-time scheduler

Author

Wang, Tianyi, Ke, Xiaolong, Huang, Lei, Negi, Vipender, Choi, Heejoo, Pullen, Wesllin, Kim, Daewook, Zhu, Yi, and Idir, Mourad

Abstract

In a Computer Numerical Controlled (CNC) finishing process, the target material removal from an optical surface is guided by the convolution between the influence function of a machine tool and its dwell time at certain points over the surface. To reduce dynamics stressing and increase machining efficiency, the dwell time must be converted to varying velocities, which are the actual inputs to the machine tool controller. Conventionally, the conversion assumed constant acceleration and relied on linear motion interpolation, which caused discontinuities in velocities. This unsmooth motion affects the material removal distribution, and, thus, the accuracy of the finished surface shape. Many modern CNC machines support the smoother, cubic-polynomial interpolated Position-Velocity-Time (PVT) motion mode; however, the conventional scheduler may fail to provide suitable velocities for the PVT. This study answers this challenge by proposing a novel PVT-based velocity scheduler that achieves smooth motion while considering CNC dynamic limits. Firstly, the principle of the PVT is explained, and the PVT-based velocity scheduler is formulated. Secondly, a quadratic programming is used to optimize the velocities by imposing the CNC dynamic constraints and the C1continuities (zeroth and first derivatives are continuous) simultaneously. Thirdly, the smoothness and accuracy of the scheduled velocities are studied on different kinds of tool paths via simulation. Finally, a sub-0.3 nm level surface finishing experiment using ion beam figuring is demonstrated to verify the feasibility of the proposed method. The PVT-based scheduler and simulator code is open-sourced.

Published
2023
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42. Adaptive Thermoforming and Structural Design of Millimeter-Wave Antenna Panels

Author

Hatfield, Zack, Peter, Alex St., Davila-Peralta, Christian, Berkson, Joel, Kim, Daewook, and Hyatt, Justin

Abstract

Future large-scale radio telescope observatories, such as the next-generation Very Large Array, involve extremely large collection areas. These collection areas are divided into smaller shaped panels, which typically require their own unique molds to manufacture. For these projects to be cost-effective, an efficient fabrication method for the shaped panels is needed. This paper outlines the development and success of a novel adaptive freeform panel molding technology that greatly improves manufacturing efficiency due to its repeatable and reusable nature. Moreover, it presents an analysis of a proposed panel structural design for the shaped panels, which incorporates a study on surface deformation due to gravity and wind loading under realistic operational conditions.

Published
2022
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