VAPR: Void-Aware Pressure Routing for Underwater Sensor Networks

Noh, Youngtae,Lee, Uichin,Wang, Paul,Choi, Brian Sung Chul,Gerla, Mario IEEE 2013 IEEE TRANSACTIONS ON MOBILE COMPUTING Vol.12 No.5

<P>Underwater mobile sensor networks have recently been proposed as a way to explore and observe the ocean, providing 4D (space and time) monitoring of underwater environments. We consider a specialized geographic routing problem called pressure routing that directs a packet to any sonobuoy on the surface based on depth information available from on-board pressure gauges. The main challenge of pressure routing in sparse underwater networks has been the efficient handling of 3D voids. In this respect, it was recently proven that the greedy stateless perimeter routing method, very popular in 2D networks, cannot be extended to void recovery in 3D networks. Available heuristics for 3D void recovery require expensive flooding. In this paper, we propose a Void-Aware Pressure Routing (VAPR) protocol that uses sequence number, hop count and depth information embedded in periodic beacons to set up next-hop direction and to build a directional trail to the closest sonobuoy. Using this trail, opportunistic directional forwarding can be efficiently performed even in the presence of voids. The contribution of this paper is twofold: 1) a robust soft-state routing protocol that supports opportunistic directional forwarding; and 2) a new framework to attain loop freedom in static and mobile underwater networks to guarantee packet delivery. Extensive simulation results show that VAPR outperforms existing solutions.</P>

HydroCast: Pressure Routing for Underwater Sensor Networks

Youngtae Noh,Uichin Lee,Saewoom Lee,Wang, Paul,Vieira, Luiz F. M.,Jun-Hong Cui,Gerla, Mario,Kiseon Kim IEEE 2016 IEEE Transactions on Vehicular Technology VT Vol.65 No.1

<P>A Sensor Equipped Aquatic (SEA) swarm is a sensor cloud that drifts with water currents and enables 4-D (space and time) monitoring of local underwater events such as contaminants, marine life, and intruders. The swarm is escorted on the surface by drifting sonobuoys that collect data from the underwater sensors via acoustic modems and report it in real time via radio to a monitoring center. The goal of this study is to design an efficient anycast routing algorithm for reliable underwater sensor event reporting to any surface sonobuoy. Major challenges are the ocean current and limited resources (bandwidth and energy). In this paper, these challenges are addressed, and HydroCast, which is a hydraulic-pressure-based anycast routing protocol that exploits the measured pressure levels to route data to the surface sonobuoys, is proposed. This paper makes the following contributions: a novel opportunistic routing mechanism to select the subset of forwarders that maximizes the greedy progress yet limits cochannel interference and an efficient underwater dead end recovery method that outperforms the recently proposed approaches. The proposed routing protocols are validated through extensive simulations.</P>

DOTS: A Propagation Delay-Aware Opportunistic MAC Protocol for Mobile Underwater Networks

Youngtae Noh,Uichin Lee,Seongwon Han,Wang, Paul,Torres, Dustin,Jinwhan Kim,Gerla, Mario IEEE 2014 IEEE Transactions on Mobile Computing Vol.13 No.4

<P>Mobile underwater networks with acoustic communications are confronted with several unique challenges such as long propagation delays, high transmission power consumption, and node mobility. In particular, slow signal propagation permits multiple packets to concurrently travel in the underwater channel, which must be exploited to improve the overall throughput. To this end, we propose the delay-aware opportunistic transmission scheduling (DOTS) protocol that uses passively obtained local information (i.e., neighboring nodes' propagation delay map and their expected transmission schedules) to increase the chances of concurrent transmissions while reducing the likelihood of collisions. Our extensive simulation results document that DOTS outperforms existing solutions and provides fair medium access even with node mobility.</P>

Infrastructure-Free Collaborative Indoor Positioning Scheme for Time-Critical Team Operations

Noh, Youngtae,Yamaguchi, Hirozumi,Lee, Uichin IEEE 2018 IEEE transactions on systems, man, and cybernetics Vol.48 No.3

<P>Indoor localization is the key infrastructure for indoor location-aware applications. In this paper, we consider an emergency scenario, where a team of soldiers or first responders perform time-critical missions in a large and complex building. In particular, we consider the case where infrastructure-based localization is not feasible for various reasons such as installation/management costs, a power outage, and terrorist attacks. We design a novel algorithm called the collaborative indoor positioning scheme (CLIPS), which does not require any pre-existing indoor infrastructure. Given that users are equipped with a signal strength map for the intended area for reference, CLIPS uses this map to compare and extract a set of feasible positions from all positions on the map when the device measures signal strength values at run time. Dead reckoning is then performed to remove invalid candidate coordinates, eventually leading to only correct positions. The main departure from existing peer-assisted localization algorithms is that our approach does not require any infrastructure or manual configuration. We perform testbed experiments and extensive simulations, and our results verify that our proposed scheme converges to an accurate set of positions much faster than existing noncollaborative solutions.</P>

인구감소에 따른 도시기반시설의 수요변화 예측과 재편방안 - 국내 교정시설 사례를 중심으로 -

노혁진(Noh, Hyeogjin),고우림(Ko, Woorim),조영태(Cho, Youngtae),백진(Baek, Jin) 대한건축학회 2022 대한건축학회논문집 Vol.38 No.11

Based on future population projections from Statistics Korea, the population decline issue in Korea is expected to intensify. Even in the planning of correctional facilities, the declining number of unconvicted prisoners was not taken into account because of the immediate overcrowding situation. The number of unconvicted prisoners also decreased due to the continuous decline in population. It has been confirmed that by 2060, the number of unconvicted prisoners will reach 74% to 50.3% of the current number of prisoners by region. Therefore, this study proposes a quantitative method for reorganizing correctional facilities to reflect the decreasing number of unconvicted prisoners in a correctional facility plan based on the number of unconvicted prisoners over the past five years and future domestic population estimation data until 2060. In the cases of the Seoul Regional Correctional Headquarter (RCH), the Daegu RCH, and the Gwangju RCH, some of the currently in use facilities must be reorganized rather than reconstructed to keep the occupancy rate close to the target occupancy rate. Meanwhile, at the Daejeon RCH, the overcrowding situation is expected to continue for the time being, even if the number of unconvicted prisoners decrease. To maintain the target occupancy rate of 85% by region through the method proposed in this study, by 2060, eight facilities in Seoul RCH, ten facilities in Daegu RCH, none in Daejeon RCH, and four facilities in Gwangju RCH should be reorganized.

StressWatch : stress tracking and timely intervention with the comodity smartwatch

Kobiljon Toshnazarov,Youngtae Noh 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.6

IMSP: an Intelligent Mobile Sensing Platform for Automatized Abnormal Behavior Detection

Kobiljon Toshnazarov,Youngtae Noh 한국통신학회 2020 한국통신학회 학술대회논문집 Vol.2020 No.2

In recent years, mobile sensing data collection has become crucial in Human-Computer Interaction research. When conducting mobile sensing studies using smartphones and wearable devices, researchers mostly address issues related to Data Quality (i.e., missing data, low accuracy, etc.). However, they do not address a problem of deviations from behavioral contexts, that can affect research finding and conclusions if not monitored efficiently in a timely manner. So far, no study has addressed this issue on an individual level. Therefore, this paper proposes Intelligent Mobile Sensing Platform (IMSP), a mobile sensing data collection platform that can efficiently detect abnormal participant behavior from mobile sensors utilizing Density-Based Local Outlier Factor and informs a researcher about it in realtime. Our study shows a promising result with our preliminary study conducted in a strictly controlled laboratory environment.

RAR: Real-Time Acoustic Ranging in Underwater Sensor Networks

Kim, Yonghun,Noh, Youngtae,Kim, Kiseon IEEE 2017 IEEE communications letters Vol.21 No.11

<P>As a core component of underwater localization, accurate acoustic ranging is quite challenging because of the harsh characteristics of underwater environments (e.g., refraction and reflection). To enhance ranging accuracy, ranging schemes employing a ray tracing model and a sound speed profile have been proposed; however, the existing schemes require numerous ray tracing iterations to perform ranging estimation within a certain range of accuracy. This renders the solutions that they generate impractical for real-time localization. In this letter, we propose a novel ranging scheme called real-time acoustic ranging (RAR). To reduce computational overhead while maintaining reliable accuracy, RAR exploits the property of ray pattern locality, whereby spatially proximate rays exhibit similar patterns. The results revealed that RAR can ensure a better tradeoff between accuracy and computational overhead than a state-of-the-art solution.</P>

Belief Propagation-Based Cognitive Routing in Maritime Ad Hoc Networks

Ghafoor, Huma,Noh, Youngtae,Koo, Insoo SAGE Publications 2016 INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWOR Vol.2016 No.-

모바일 및 웨어러블 기기를 위한 실험 샘플링 생태순간평가 플랫폼 관련 연구

송치헌(ChiHeon Song),노영태(Youngtae Noh) 한국정보기술학회 2021 Proceedings of KIIT Conference Vol.2021 No.11

HCI(Human Computer Interaction)와 인간 중심 연구에서 EMA (Ecological Momentary Assessment) 방법 및 모바일 기기는 떼려야 뗄 수 없는 관계에 있지만 기존의 모바일 기기를 이용한 EMA 샘플링 플랫폼은 높은 비용으로 인해 접근하기 어려웠으며 구축하기에도 어려움이 있었다. 따라서 이 논문은 인간 중심 연구를 위한 EMA 설문 전달에 대해 효율성을 높이고 더 성실한 설문 참여를 독려하는 방식의 새로운 모바일 및 웨어러블 기기용 실험 샘플링 어플리케이션 디자인을 제공한다. In Human Computer Interaction (HCI) and human-centered research, EMA (Ecological Momentary Assessment) methods and mobile devices are inextricably linked, but the existing EMA sampling platform using mobile devices was difficult to access due to high cost and difficult to build. Therefore, this paper presents the design of a novel experimental sampling application for mobile and wearable devices in a way that increases efficiency and encourages more sincere survey participation in the delivery of EMA surveys for human-centered research.