Dynamic Transmission and Delay Optimization Random Access for Reduced Power Consumption
IEEE Access, vol. 12, pp. 55033–55050, April 2024
Myongji University · DAN Lab · Integrated MS–PhD 명지대학교 · DAN 연구실 · 석·박사 통합과정
Multi-link contention stops being tractable the moment one radio has to serve three bands.
라디오 하나가 세 대역을 감당하는 순간, 멀티링크 경쟁은 풀리지 않는 문제가 됩니다.
Under the EMLSR active-link constraint the queues couple across links, so single-link Bianchi analysis no longer transfers. I build Markov/fixed-point closures that stay analytically auditable — exact under saturated STR, an availability-based approximation under EMLSR with its validity range made explicit — and drive the contention window from observables the MAC already has: collision rate, blocked ratio, queue backlog, head-of-line excess.
EMLSR의 단일 활성 링크 제약 아래에서는 큐가 링크 간에 결합되어, 단일 링크 Bianchi 해석이 그대로 옮겨가지 않습니다. 분석 가능성을 유지하는 Markov/고정점 폐형을 세우고 — 포화 STR에서는 엄밀하게, EMLSR에서는 유효 범위를 명시한 가용성 기반 근사로 — MAC이 이미 관측하는 값(충돌률, 차단 비율, 큐 적체, HOL 초과)으로 경쟁 윈도우를 제어합니다.
Ultra-high reliability is a promise about the worst one percent, not about the average.
초고신뢰성은 평균이 아니라 최악의 1%에 대한 약속입니다.
So the tail belongs in the objective. I carry p99 and p99.9 deadline-violation rates as Lyapunov drift-plus-penalty duals, price cross-BSS congestion once per beacon, and weight federated aggregation by measured interference rather than a plain mean — because averaging dilutes exactly the access points that need the most help.
그래서 꼬리 분위를 목적함수에 넣습니다. p99·p99.9 지연 위반율을 Lyapunov drift-plus-penalty의 쌍대변수로 다루고, 비컨마다 BSS 간 혼잡 가격을 한 번 산출하며, 연합 집성은 단순 평균이 아니라 측정된 간섭에 비례해 가중합니다 — 평균은 정작 가장 도움이 필요한 AP의 갱신을 희석시키기 때문입니다.
Deployed video arrives compressed, dropped and late. Models are usually trained as if it did not.
실제 운용 환경의 영상은 압축되고, 유실되고, 늦게 도착합니다. 모델은 대개 그렇지 않은 것처럼 학습됩니다.
My doctoral work makes attention degradation-aware and explainable: simulate packet loss, jitter and compression on the input, then teach spatial and temporal attention to weight what actually survived. Applied to weakly-supervised anomaly detection — where anticipation and detection share one representation — and to action recognition under a real compute budget.
학위 연구는 어텐션을 열화 인지적이고 설명 가능하게 만드는 데 있습니다. 입력에 패킷 손실·지터·압축을 시뮬레이션한 뒤, 공간·시간 어텐션이 살아남은 정보에 가중치를 두도록 학습시킵니다. 예측과 탐지가 하나의 표현을 공유하는 약지도 이상 탐지, 그리고 실제 연산 예산 안에서의 행동 인식에 적용합니다.
The same channel state that tells a MAC how bad the link is can also tell you where a body is.
링크 상태를 MAC에 알려주는 바로 그 채널 정보가, 사람이 어디에 어떤 자세로 있는지도 알려줍니다.
On MM-Fi, reported gains largely reflect better localization — Procrustes-aligned errors sit close to a mean-posture reference. So I route CSI by physics: sanitized per-antenna phase carries location, an amplitude-led composite carries posture, and a motion-consistency loss recovers the posture dynamics that pure localization misses.
MM-Fi에서 보고되는 성능 향상의 상당 부분은 사실 위치 추정 개선입니다 — Procrustes 정렬 오차가 평균 자세 기준선에 가깝습니다. 그래서 CSI를 물리적으로 분기시킵니다. 정제된 안테나별 위상은 위치를, 진폭 중심 합성 표현은 자세를 담당하며, 움직임 일관성 손실이 위치 추정만으로는 놓치는 자세 동역학을 회복합니다.
Multi-link contention resists closed-form analysis once the EMLSR single-active-radio constraint couples queues across bands. I build Markov/fixed-point closures that stay analytically auditable, then drive contention windows from MAC observables inside the standard EDCA loop.
EMLSR의 단일 활성 라디오 제약이 대역 간 큐를 결합시키면 멀티링크 경쟁은 닫힌 형태로 풀리지 않습니다. 분석 가능성을 유지하는 Markov/고정점 폐형을 세우고, 표준 EDCA 루프 안에서 MAC 관측값으로 경쟁 윈도우를 제어합니다.
Ultra-high reliability is a tail problem, not a mean problem. I use Lyapunov drift-plus-penalty to put p99 and p99.9 violation rates directly into the learning signal, with federated aggregation weighted by measured interference rather than plain averaging.
초고신뢰성은 평균이 아니라 꼬리 분위의 문제입니다. Lyapunov drift-plus-penalty로 p99·p99.9 위반율을 학습 신호에 직접 넣고, 단순 평균 대신 측정된 간섭에 비례한 가중치로 연합 집성을 수행합니다.
Packet loss, jitter and aggressive compression are the normal operating condition for deployed video, not an edge case. My doctoral work makes attention degradation-aware and explainable, spanning anomaly anticipation, action recognition and device-free CSI sensing.
패킷 손실, 지터, 강한 압축은 예외가 아니라 실제 운용 환경의 기본값입니다. 학위 연구는 어텐션을 열화 인지적이고 설명 가능하게 만드는 데 있으며, 이상 예측·행동 인식·비접촉 CSI 센싱을 포함합니다.
IEEE Access, vol. 12, pp. 55033–55050, April 2024
ICT Express, vol. 9, no. 2, pp. 241–246, 2023
International Conference on Innovative Mobile and Internet Services in Ubiquitous Computing (IMIS), 2025
International Conference on Broadband and Wireless Computing, Communication and Applications (BWCCA), 2024
International Conference on ICT Convergence (ICTC), 2023
International Conference on Innovative Mobile and Internet Services in Ubiquitous Computing (IMIS), 2022
International Conference on Ubiquitous and Future Networks (ICUFN), July 2021
International Conference on Innovative Mobile and Internet Services in Ubiquitous Computing (IMIS), 2021
International Conference on Innovative Mobile and Internet Services in Ubiquitous Computing (IMIS), 2020
IEEE Transactions on Mobile Computing — under review — 심사 중
IEEE 802.11bn Ultra High Reliability (UHR) extends multi-link operation toward a reliability-oriented MAC, but multi-link contention under the EMLSR active-link constraint resists closed-form analysis. We develop a Markov/fixed-point closure for three-band MLDs coexisting with single-link legacy stations: exact under saturated, per-link-independent STR; reducing to an availability-based approximation under saturated EMLSR with an explicit validity range; and extending to unsaturated traffic through per-link Bernoulli arrivals. On top of it we build a controller that adapts the per-link minimum contention window from MAC observables inside the standard EDCA/EMLSR loop. Against SLD, STR-MLD and static-EMLSR baselines it raises throughput by 10.6%, lowers 95th-percentile HOL-service delay by 28%, and improves Jain's fairness from 0.910 to 0.954 at 48 stations. Triangulation across the analytical model, a discrete-event simulator and ns-3 closes within a 2–4% mean relative gap.
Under review심사 중
IEEE 802.11bn defines ultra-high reliability through per-BSS deadline-violation-rate targets. We study these constraints in dense multi-band deployments with heterogeneous AP link sets. LyMAPPO combines independent per-AP PPO with drop-inclusive rate-form Lyapunov duals, one dual-derived congestion price per beacon for cross-BSS coordination, and an auxiliary lower-tail quantile critic. Training and evaluation use an ns-3-in-the-loop environment with 16 APs, three bands, shared-buffer multi-link operation and Markov channels. Across 16 seeds with 110 s episodes, LyMAPPO achieves 15.1/16 feasible BSSs and a network p99 of 0.0017 — 6.1× to 25× lower than three static baselines. The drift-plus-penalty analysis accounts for clipping and establishes a run-time dual-stability condition under the Slater assumption.
Under review심사 중
STCA-ViT is a hybrid framework integrating a VideoMAE ViT-Base backbone with bidirectional spatio-temporal cross-attention, Sobel-based boundary detection for motion gating, and YOLO-based person attention in parallel. It adds residual contribution fusion with gradient reversal for feature diversity, orthogonal regularization, a multi-head ensemble classifier, and an optional weakly-supervised temporal action localization head that recycles motion features into frame-level scores without temporal annotations. STCA-ViT reaches 90.46% Top-1 on HMDB-51 — above VideoMAE V2 ViT-g (86.08%) — with 98.29% on UCF-101, 79.44% on Kinetics-400 and 65.01% on Something-Something-v2, using 110M parameters and 305 GFLOPs.
Under review심사 중
WiFi channel state information supports device-free 3D pose estimation, but posture and motion remain hard to recover across subjects and scenes. On MM-Fi, recent estimators' Procrustes-aligned errors (99.8–106.2 mm) sit close to a mean-posture reference (99.4–103.6 mm), indicating much of the reported gain comes from localization. PhysRoute-Fi separates CSI into physical components and assigns them to pose factors: sanitized per-antenna phase is fused with an amplitude-led composite representation for location, while the composite representation drives a graph-convolutional posture decoder. With one-time enrollment, a motion-consistency loss recovers about 93% of the aggregate inter-frame displacement magnitude and reaches 102.7 mm MPJPE and 65.5 mm PA-MPJPE.
Under review심사 중
Weakly-supervised video anomaly detection localizes frame-level anomalies using only video-level binary labels. Existing methods treat anomaly detection and risk anticipation as independent tasks, discarding cross-task predictive cues. SEAR jointly performs multi-horizon risk anticipation and MIL-based detection through a shared representation via three contributions: a Cross-Task Anticipation Gate, a zero-initialized scalar that modulates detection features with anticipation risk scores; Temporal Contrastive MIL, a hinge-loss objective separating peak anomaly scores from all normal scores; and Curriculum Pseudo-Labeling with Negative Mining. On UCF-Crime, SEAR reaches 85.36% frame-level AUC with frozen dual encoders (~0.59M trainable parameters), and 87.78% AUC under triple-encoder fusion — the highest among frozen-encoder methods. It detects 89% of anomalous videos before annotated event onset.
Korean Institute of Communications and Information Sciences (KICS) conferences and JCCI. Titles are given as published, in Korean.
한국통신학회(KICS) 종합학술발표회 및 통신정보 합동학술대회(JCCI) 발표 논문입니다.
Interference-Weighted Federated Multi-Agent PPO for Ultra-Reliable Coordinated MLO Scheduling
Shared Evidential Anomaly and Risk Detection
Quality-Aware Adaptive Federated Deep Q-Network for Distributed Multi-AP Wi-Fi
Predictive Resource Intelligence for Multi-Link Efficiency in Wi-Fi
Video classification with dynamic convolution and multi-scale spatio-temporal attention
Research trends in unknown object detection for autonomous driving
Improving GAN image quality with a dual-generator structure
Sectorized random access with 2-pair UE NOMA in 5G mMTC
A multi-output model for deep learning on multi-class datasets
Adaptive contention window for internal interference in multi-link operation
VX-GAN: a validation and explainable GAN model for data augmentation
Face recognition model for small embedded systems based on CNN
Road-density anomaly detection from UAV semantic object recognition
Service-aware prioritization by network requirement in SDN
FedSD: federated learning using per-user weight standard deviation
Lifestyle-based depression prediction from NHANES data
A 5G-V2X accident-prevention system in MEC environments
Korean patent applications filed through the Myongji University Industry–Academic Cooperation Foundation, with Prof. Hyunhee Park.
명지대학교 산학협력단을 통해 박현희 교수와 공동 출원한 국내 특허입니다.
Ref. PD241137 · filed 23 Dec 20242024.12.23 출원
Ref. PD241138 · filed 23 Dec 20242024.12.23 출원
Ref. PD241139 · filed 23 Dec 20242024.12.23 출원
Ref. PD241140 · filed 23 Dec 20242024.12.23 출원
10-2023-0196634 · published KR 10-2025-0104336 A, 8 Jul 2025공개 KR 10-2025-0104336 A, 2025.07.08
10-2022-0024885 · published KR 10-2023-0127508 A, 1 Sep 2023공개 KR 10-2023-0127508 A, 2023.09.01
RS-2024-00469138
Vision models targeted at domestic AI accelerators — the constraint that pushed my action-recognition work toward accuracy-per-GFLOP rather than accuracy alone.
국산 AI 가속기를 대상으로 하는 비전 모델 개발. 정확도만이 아니라 GFLOP당 정확도를 기준으로 행동 인식 연구를 설계하게 된 배경입니다.
2022R1A2C2005705
Distributed learning for MAC-layer decisions in UAV-assisted networks; the origin of my multi-UAV energy and Age-of-Information work.
UAV 기반 네트워크의 MAC 계층 의사결정을 위한 분산 학습 연구. 다중 UAV 에너지·AoI 최적화 연구의 출발점입니다.
Innopia Technologies (이노피아테크)
Person-centred clip analysis over a broadcast video corpus: CLIP-based embeddings, scene and appearance analysis, and retrieval built on top of them.
방송 영상 코퍼스를 대상으로 한 인물 중심 클립 분석. CLIP 기반 임베딩, 장면·출연 분석 및 이를 활용한 검색 파이프라인을 구축했습니다.
Myongji University · Department of Information and Communication Engineering 명지대학교 정보통신공학과
Doctoral thesis: Attention-Based Robust Learning Method for Explainable Video Understanding under Communication Constraints — advised by Prof. Hyunhee Park.
학위논문: 통신 환경을 고려한 설명 가능한 비디오 이해를 위한 Attention 기반 강건 학습 기법에 관한 연구 — 지도교수 박현희.
Korea Bible University 한국성서대학교