우용 정

Mr. 우용 정

orcid

Research Focus & Metrics

Academic Career Length

3Years (2024-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 October 2024 in Drones
Verified
Journal Article
Open access
PDF file
우정우용 정
우용 정
CPChangmin Park
Changmin Park
승이승현 이
승현 이
Hwangnam KimHwangnam Kim
Hwangnam Kim
This paper presents a drone system that uses an improved network topology and MultiAgent Reinforcement Learning (MARL) to enhance mission performance in Unmanned Aerial Vehicle (UAV) swarms across various scenarios. We propose a UAV swarm system that allows drones to efficiently perform tasks with limited information sharing and optimal action selection through our Efficient Self UAV Swarm Network (ESUSN) and reinforcement learning (RL). The system reduces communication delay by 53% and energy consumption by 63% compared with traditional MESH networks with five drones and achieves a 64% shorter delay and 78% lower energy consumption with ten drones. Compared with nonreinforcement learning-based systems, mission performance and collision prevention improved significantly, with the proposed system achieving zero collisions in scenarios involving up to ten drones. These results demonstrate that training drone swarms through MARL and optimized information sharing significantly increases mission efficiency and reliability, allowing for the simultaneous operation of multiple drones.

8 May 2024 in IEEE Access
Verified
Journal Article
Open access
NYNamkyung Yoon
Namkyung Yoon
우정우용 정
우용 정
Hwangnam KimHwangnam Kim
Hwangnam Kim
In this paper, we present an innovative methodology for generating virtual received signal strength indicator (RSSI) fingerprint maps to improve indoor localization systems and wireless communication systems using RSSI. Focusing on the challenge of extensive labor and time required in traditional data collection, we propose a generative model that combines customized attention mechanism with a conditional variational autoencoder (cVAE), leveraging datasets compiled from direct measurements of RSSI values from different access points in a real-world indoor environment. Our model uniquely synthesizes high-quality virtual RSSI maps, significantly reducing the need for extensive physical data collection while enhancing the accuracy and efficiency of indoor positioning systems. By integrating measured data with innovative data generation techniques, our approach offers a novel solution to indoor localization challenges. In addition, this model can augment high-quality synthetic data for indoor wireless signals to expand the volume of available data. We quantitatively demonstrate the effectiveness of our model, showing an average improvement of over 40% in Euclidean distance errors across several machine learning algorithms compared to existing methods. Our experiments validate that the virtual RSSI fingerprint map yields accurate position estimates, with performance enhancements observed in algorithms that confirm the utility in real-world scenarios. The contribution of our research improves indoor localization systems by improving indoor positioning accuracy and addresses the limitations of traditional fingerprinting methods, setting the stage for future innovations in wireless communication.

7 July 2024 in Chemosensors
Verified
Journal Article
Open access
PDF file
NYNamkyung Yoon
Namkyung Yoon
우정우용 정
우용 정
Hwangnam KimHwangnam Kim
Hwangnam Kim
The gas chromatography analysis method for chemical substances enables accurate analysis to precisely distinguish the components of a mixture. This paper presents a technique for augmenting time-series data of chemicals measured by gas chromatography instruments with artificial intelligence techniques such as generative adversarial networks (GAN). We propose a novel GAN algorithm called GCGAN for gas chromatography data, a unified model of autoencoder (AE) and GAN for effective time-series data learning with an attention mechanism. The proposed GCGAN utilizes AE to learn a limited number of data more effectively. We also build a layer of high-performance generative adversarial neural networks based on the analysis of the features of data measured by gas chromatography instruments. Then, based on the proposed learning, we synthesize the features embedded in the gas chromatography data into a feature distribution that extracts the temporal variability. GCGAN synthesizes the features embedded in the gas chromatography data into a feature distribution that extracts the temporal variability of the data over time. We have fully implemented the proposed GCGAN and experimentally verified that the data augmented by the GCGAN have the characteristic properties of the original gas chromatography data. The augmented data demonstrate high quality with the Pearson correlation coefficient, Spearman correlation coefficient, and cosine similarity all exceeding 0.9, significantly enhancing the performance of AI classification models by 40%. This research can be effectively applied to various small dataset domains other than gas chromatography data, where data samples are limited and difficult to obtain.

3 July 2026 in Applied Sciences
Verified
Journal Article
Open access
PDF file
SKSanghyun Kim
Sanghyun Kim
Seungho YooSeungho Yoo
Seungho Yoo
KJKim Min Jun
Kim Min Jun
UJUkhyun Jeong
Ukhyun Jeong
우정우용 정
우용 정
Hwangnam KimHwangnam Kim
Hwangnam Kim
Large-scale UAV data collection creates a tension among wide-area coverage, operational efficiency, and delivery continuity. Data must be continuously delivered to a base-station coordinator, but real-time replanning becomes increasingly difficult as the number of sensors and UAVs grows. Standard vehicle-routing methods slow down once routes have to be regenerated often, while reinforcement learning struggles with fixed-wing UAVs that cannot hover or turn sharply. We address this with a two-layer framework. In the lower layer, multirotor UAVs visit sensor nodes and buffer the collected payload until it is retrieved by a fixed-wing UAV. Their routes come from clustering the nodes and solving a capacitated vehicle routing problem within each cluster, with the cost biased toward older data and a short cooldown against immediate revisits. In the upper layer, fixed-wing UAVs deliver the buffered payload to the base-station coordinator, guided by a Multi-Agent Proximal Policy Optimization (MAPPO) policy that receives a local buffer-summary map and selected high-priority cells from a compact global summary. A spacing reward encourages separation before agents enter close-proximity states, instead of only penalizing collisions afterward. Component-level experiments show that the lower-layer planner handles up to 600 active routing targets within 1.3 s on average and that the age/cooldown objective improves freshness and revisit behavior. In integrated simulations with 1000 nodes, 32 multirotor UAVs, and 2 fixed-wing UAVs, the learned fixed-wing policy maintains collection performance comparable to a strong exclusive greedy baseline while recording no collision or persistent-proximity termination events over the reported data-generation-rate sweep. These results support the proposed framework as a scalable coordination-layer design for dynamic sensor workloads, where adaptive multirotor routing and motion-constrained fixed-wing retrieval are evaluated together under a shared data-generation workload.

18 February 2026 in arXiv
Verified
Preprint
Open access
PDF file
NYNamkyung Yoon
Namkyung Yoon
KYKyeonghyun Yoo
Kyeonghyun Yoo
우정우용 정
우용 정
SKSanghong Kim
Sanghong Kim
Hwangnam KimHwangnam Kim
Hwangnam Kim
Despite the continuous research and evolution of language models, they sometimes underperform previous versions. Existing approaches to overcome these challenges are resource-intensive, highlighting the need for alternatives that enable immediate action. We assume that each language model has a local module inside that is suitable for a specific function. First, this work identifies a set of modules showing consistent and local activation changes under an inference workload through activation-based analysis. Subsequently, we transplant an internal module that is properly activated for a specific task into the target model, leading to immediate and measurable functional changes without additional training or fine-tuning. To experimentally demonstrate the effectiveness of the transplant technique, we quantify the relationship between transplant strength and performance improvement under different conditions for two language models. In the cross-generation setting, we find that transplanting activation-selected modules can substantially improve the underperforming model, reaching up to twice the target baseline and achieving gap-based recovery above 100%. Moreover, in transplant experiments between a base model and its instruction-tuned counterpart, transplantation improves the underperforming model toward the stronger baseline, yielding up to about 2.33 times the target baseline with gap-based recovery reaching up to 100% in the best case. These results show that meaningful capacity transfer can be realized through the implantation of highly localized modules implied by language models. Overall, this work provides empirical evidence for task-localized modularity in language models and presents a new research area: model transplantation.