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1,381 results on '"Park, Sung-Ho"'

1. Development of In-Pipe Inspection Robot for Large-Diameter Water Pipe

Author

Jeon, Kwang-Woo, Chung, Hyun-Joon, Jung, Eui-Jung, Park, Sung-Ho, Son, So-Eun, Bae, Jong-Ho, Chung, Goo-Bong, Yi, Hak, Kacprzyk, Janusz, Series Editor, Gomide, Fernando, Advisory Editor, Kaynak, Okyay, Advisory Editor, Liu, Derong, Advisory Editor, Pedrycz, Witold, Advisory Editor, Polycarpou, Marios M., Advisory Editor, Rudas, Imre J., Advisory Editor, Wang, Jun, Advisory Editor, Lee, Soon-Geul, editor, An, Jinung, editor, Chong, Nak Young, editor, Strand, Marcus, editor, and Kim, Joo H., editor

Published
2024
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6. An Energy-efficient Aerial Backhaul System with Reconfigurable Intelligent Surface

Author

Jeon, Hong-Bae, Park, Sung-Ho, Park, Jaedon, Huang, Kaibin, and Chae, Chan-Byoung

Subjects
Electrical Engineering and Systems Science - Signal Processing, Computer Science - Information Theory
Abstract

In this paper, we propose a novel wireless architecture, mounted on a high-altitude aerial platform, which is enabled by reconfigurable intelligent surface (RIS). By installing RIS on the aerial platform, rich line-of-sight and full-area coverage can be achieved, thereby, overcoming the limitations of the conventional terrestrial RIS. We consider a scenario where a sudden increase in traffic in an urban area triggers authorities to rapidly deploy unmanned-aerial vehicle base stations (UAV-BSs) to serve the ground users. In this scenario, since the direct backhaul link from the ground source can be blocked due to several obstacles from the urban area, we propose reflecting the backhaul signal using aerial-RIS so that it successfully reaches the UAV-BSs. We jointly optimize the placement and array-partition strategies of aerial-RIS and the phases of RIS elements, which leads to an increase in energy-efficiency of every UAV-BS. We show that the complexity of our algorithm can be bounded by the quadratic order, thus implying high computational efficiency. We verify the performance of the proposed algorithm via extensive numerical evaluations and show that our method achieves an outstanding performance in terms of energy-efficiency compared to benchmark schemes., Comment: 17 pages, 15 figures

Published
2021

23. Development of an In-Pipe Inspection Robot for Large-Diameter Water Pipes.

Author

Jeon, Kwang-Woo, Jung, Eui-Jung, Bae, Jong-Ho, Park, Sung-Ho, Kim, Jung-Jun, Chung, Goobong, Chung, Hyun-Joon, and Yi, Hak

Subjects
MAGNETIC flux leakage, PIPE, PIPELINE inspection, ELECTRIC propulsion, ROBOT design & construction, ROBOTS, MOBILE robots, WIRELESS communications
Abstract

This paper describes the development of an in-pipe inspection robot system designed for large-diameter water pipes. The robot is equipped with a Magnetic Flux Leakage (MFL) sensor module. The robot system is intended for pipes with diameters ranging from 900 mm to 1200 mm. The structure of the in-pipe inspection robot consists of the front and rear driving parts, with the inspection module located centrally. The robot is powered by 22 motors, including eight wheels with motors positioned at both the bottom and the top for propulsion. To ensure that the robot's center aligns with that of the pipeline during operation, lifting units have been incorporated. The robot is equipped with cameras and LiDAR sensors at the front and rear to monitor the internal environment of the pipeline. Pipeline inspection is conducted using the MFL inspection modules, and the robot's driving mechanism is designed to execute spiral maneuvers while maintaining contact with the pipeline surface during rotation. The in-pipe inspection robot is configured with wireless communication modules and batteries, allowing for wireless operation. Following its development, the inspection robot underwent driving experiments in actual pipelines to validate its performance. The field test bed used for these experiments is approximately 1 km in length. Results from the driving experiments on the field test bed confirmed the robot's ability to navigate various curvatures and obstacles within the pipeline. It is posited that the use of the developed in-pipe inspection robot can reduce economic costs and enhance the safety of inspectors when examining aging pipes. [ABSTRACT FROM AUTHOR]

Published
2024
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31. Frequency Assignment Problem with Net Filter Discrimination Constraints

Author

Yilmaz, H. Birkan, Koo, Bon-Hong, Park, Sung-Ho, Park, Hwi-Sung, Ham, Jae-Hyun, and Chae, Chan-Byoung

Subjects
Computer Science - Networking and Internet Architecture
Abstract

Managing radio spectrum resources is a crucial issue. The frequency assignment problem (FAP) basically aims to allocate, in an efficient manner, limited number of frequencies to communication links. Geographically close links, however, cause interference, which complicates the assignment, imposing frequency separation constraints. The FAP is closely related to the graph-coloring problem and it is an NP-hard problem. In this paper, we propose to incorporate the randomization into greedy and fast heuristics. As far as being implemented, the proposed algorithms are very straight forward and are without system parameters that need tuned. The proposed algorithms significantly improve, quickly and effectively, the solutions obtained by greedy algorithms in terms of the number of assigned frequencies and the range. The enhanced versions of proposed algorithms perform close to the lower bounds while running for a reasonable duration. Another novelty of our study is its consideration of the net filter discrimination effects in the communication model. Performance analysis is done by synthetic and measured data, where the measurement data includes the effect of the real 3-dimensional (3D) geographical features in the Daejeon region in Korea. In both cases, we observe a significant improvement by employing randomized heuristics.

Published
2016

39. How Predictable Is Exceptional Venture Growth? Using Machine Learning to Predict Unicorn Ventures.

Author

Kotha, Suresh B, Hallen, Benjamin L., Park, Sung Ho, Allen, Ryan, and Shin, Seowon Joseph

Abstract

We examine how predictable is eventually achieving unicorn status for early-stage entrepreneurial startups (i.e., achieving a billion-dollar valuation while private). While past studies have examined factors impacting new firm growth, they have not explored the overall predictability of growth or examined the exceptional growth of outlier startups in modern entrepreneurship. Predicting outlier growth is essential for many stakeholders – including potential investors, employees, and partners – who wish to discern which startups to work with. We examine this using state-of-the-art Machine Learning (ML) algorithms tailored for predictive models on rich early founder and venture attributes across 2,845 startups. When tasked with pinpointing the 10 startups with the highest probability of becoming unicorns in the holdout test set, our most effective model successfully identifies 2.3 actual unicorns on average from its top 10 predictions. While a 3- fold improvement over pure chance, this predictability is still moderate. We consider how this extends past scholarship on the benefits of early founder, industry, and resource advantages to show their role in also driving outlier growth, while additionally suggesting that much variance remains for scholarship on new firm growth to explain. We also elaborate on how prediction-oriented modern ML methods open new avenues for entrepreneurial research. [ABSTRACT FROM AUTHOR]

Published
2024
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46. The effects of globalization on macroeconomic dynamics in a trade-dependent economy: The case of Korea

Author

Milani, Fabio and Park, Sung Ho

Subjects
Decent Work and Economic Growth, Globalization, Inflation dynamics, Global slack hypothesis, Inflation expectations, Openness, Small open economy DSGE model, Korea, E31, E32, E50, E52, E58, F41, F62, Small open eonomy DSGE model, Inflation Dynamics, Global Slack Hypothesis, Inflation Expectations, Small Open Economy DSGE Model, Applied Economics, Econometrics, Banking, Finance and Investment, Economics
Abstract

This paper studies the implications of globalization for the dynamics of macroeconomic variables over the business cycle for a small open trade-dependent economy, such as South Korea.We study the impact of globalization through the lens of a structural model. Globalization is modeled as a time-varying degree of openness in the economy. We estimate the model allowing for non-fully rational expectations, learning by economic agents, and incomplete international financial markets.The empirical results show that globalization led to important changes in the macroeconomic environment. Domestic variables have become much more sensitive toward global measures over the 1991-2012 sample. In particular, domestic output and inflation are significantly affected by global output. Fluctuations in Korean output, inflation, and interest rates, which were driven for the most part by domestic shocks in the early 1990s, are, by the end of the sample, due in large part (roughly 70%) to global shocks (and shocks that are open-economy in nature).

Published
2015

50. Embedded minimal and constant mean curvature annulus touching spheres

Author

Park, Sung-Ho

Subjects
Mathematics - Differential Geometry, 53A10
Abstract

We show that a compact embedded minimal or constant mean curvature annulus with non-vanishing Gaussian curvature which is tangent to two spheres of same radius or tangent to a sphere and meeting a plane in constant contact angle is rotational., Comment: 10 pages

Published
2010

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