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Continual Unsupervised Domain Adaptation for Semantic Segmentation [article]

Joonhyuk Kim, Sahng-Min Yoo, Gyeong-Moon Park, Jong-Hwan Kim
2021 arXiv   pre-print
The source code is available at  ... 
arXiv:2010.09236v2 fatcat:zou42auycfd7zihjb3qch2wgv4

Measuring User Similarity Using Electric Circuit Analysis: Application to Collaborative Filtering

Joonhyuk Yang, Jinwook Kim, Wonjoon Kim, Younghwan Kim
2012 Social Science Research Network  
This work opens new opportunities for interdisciplinary research between physics and computer science and the development of new recommendation systems Citation: Yang J, Kim J, Kim W, Kim YH (2012) Measuring  ... 
doi:10.2139/ssrn.2322391 fatcat:lao43hdvo5adbh3o4xm746vehq

Measuring User Similarity Using Electric Circuit Analysis: Application to Collaborative Filtering

Joonhyuk Yang, Jinwook Kim, Wonjoon Kim, Young Hwan Kim, Petter Holme
2012 PLoS ONE  
This work opens new opportunities for interdisciplinary research between physics and computer science and the development of new recommendation systems Citation: Yang J, Kim J, Kim W, Kim YH (2012) Measuring  ... 
doi:10.1371/journal.pone.0049126 pmid:23145095 pmcid:PMC3492312 fatcat:ngufuskthbgwfc5qrujrjs6drm

Formation of Matter-Wave Polaritons in an Optical Lattice [article]

Joonhyuk Kwon, Youngshin Kim, Alfonso Lanuza, Dominik Schneble
2021 arXiv   pre-print
The polariton, a quasiparticle formed by strong coupling of a photon to a matter excitation, is a fundamental ingredient of emergent photonic quantum systems ranging from semiconductor nanophotonics to circuit quantum electrodynamics. Exploiting the interaction between polaritons has led to the realization of superfluids of light as well as of strongly correlated phases in the microwave domain, with similar efforts underway for microcavity exciton-polaritons. Here, we develop an ultracold-atom
more » ... nalogue of an exciton-polariton system in which interacting polaritonic phases can be studied with full tunability and without dissipation. In our optical-lattice system, the exciton is replaced by an atomic excitation, while an atomic matter wave is substituted for the photon under a strong dynamical coupling. We access the band structure of the matter-wave polariton spectroscopically by coupling the upper and lower polariton branches, and explore polaritonic many-body transport in the superfluid and Mott-insulating regimes, finding quantitative agreement with our theoretical expectations. Our work opens up novel possibilities for studies of polaritonic quantum matter.
arXiv:2109.02243v1 fatcat:2x4yhpowerf7zgs4uzmyfxf3pa

Multiband and array effects in matter-wave-based waveguide QED [article]

Alfonso Lanuza, Joonhyuk Kwon, Youngshin Kim, Dominik Schneble
2021 arXiv   pre-print
Recent experiments on spontaneous emission of atomic matter waves open a new window into the behavior of quantum emitters coupled to a waveguide. Here we develop an approach based on infinite products to study this system theoretically, without the need to approximate the band dispersion relation of the waveguide. We solve the system for a one-dimensional array of one, multiple and an infinite number of quantum emitters and compare with the experiments. This leads to a detailed characterization
more » ... of the decay spectrum, with a family of in-gap bound states, new mechanisms for enhanced Markovian emission different from superradiance, and the emergence of matter-wave polaritons.
arXiv:2108.11759v1 fatcat:eswaslrcyjchtmyt33a7n2bqqq

A High Precision Ranging Scheme for IEEE802.15.4a Chirp Spread Spectrum System

Na Young KIM, Sujin KIM, Youngok KIM, Joonhyuk KANG
2009 IEICE transactions on communications  
This letter proposes a high precision ranging scheme based on the time of arrival estimation technique for the IEEE 802.15.4a chirp spread spectrum system. The proposed scheme consists of a linear channel impulse response estimation process with the zero forcing or minimum mean square error technique and the multipath delay estimation process with matrix pencil algorithm. The performance of the proposed scheme is compared with that of a well known MUSIC algorithm in terms of computational
more » ... xity and ranging precision. Simulation results demonstrate that the proposed scheme outperforms the MUSIC algorithm even though it has comparatively lower computational complexity. key words: time of arrival, ranging, chirp spread spectrum
doi:10.1587/transcom.e92.b.1057 fatcat:pxxoshjtq5alja5jobhtjm2gzi

High Accurate Two-Dimensional Geo-Location System for Social Safety Robot

Sujin Kim, Gon-Woo Kim, Kyung-Tae Nam, Sang-Moo Lee, Joonhyuk Kang, Woong-Hee Shon, Jeahwan Kim
2008 IFAC Proceedings Volumes  
In this paper, we propose an efficient two-dimensional geo-location system for social safety robot, where its location is obtained by direction of arrival (DOA) and time of arrival (TOA) of the radio signal. The proposed system requires two reference signals while the conventional systems generally deploy more than three reference signals. For estimating TOA and DOA information together, we employ a multiple signal classification (MUSIC) algorithm. The simulation results show that the proposed
more » ... eo-location system achieves accuracy within 3 meters error in 2 kilo-meters coverage which is constraint for mobile social safety robot.
doi:10.3182/20080706-5-kr-1001.00287 fatcat:ghlvnyudpfednfdrqafxwgwrqe

Effect of Lithium Doping on the Transport Properties of MoO$ _{3}$ Ceramics

Yujung AHN, Gowoon KIM, Joonhyuk LEE, Hyun Jung KIM, Jaekwang LEE, Hyoungjeen JEEN*
2019 New Physics Sae Mulli  
In this research, we studied the effects of lithium doping on the transport properties of MoO3 ceramics. A series of lightly lithium-doped MoO3 ceramics was prepared: 2, 4 and 8 mol% Li-doped MoO3. The x-ray diffraction analysis confirmed that the typical MoO3 structures were retained at the low doping. However, from laser-induced-breakdown spectroscopy, the differences in the peak intensities of the doped samples clearly indicates that lithium ions are successfully incorporated into the
more » ... s in different amounts. To see the effects of the lithium doping on the transport properties in the MoO3 lattices, impedance spectroscopy is used in the capacitor geometry. A systematic increase in the overall bulk conductivity and a faster relaxation behavior were observed when the doping level was increased. Lastly, when the doping level was increased the activation energy was drastically decreased, which indicates that the lithium facilitates transport along a 2D path.
doi:10.3938/npsm.69.1016 fatcat:ns4j35v4bnclzhebpjhvp4gvnq

A novel orthogonal space-time-frequency block code for OFDM systems

Keonkook Lee, Youngok Kim, Joonhyuk Kang
2009 IEEE Communications Letters  
Student Member, IEEE, Youngok Kim, and Joonhyuk Kang, Members, IEEE Abstract-In this letter, we propose an orthogonal spacetime-frequency block code for orthogonal frequency division multiplexing (STFBC-OFDM  ...  Kim is with the Department of Electronic Engineering, Kwangwoon University, Korea (e-mail:  ... 
doi:10.1109/lcomm.2009.090680 fatcat:or4j2kcs5rcjha5nlngkoip3sy

Protect Your Sky: A Survey of Counter Unmanned Aerial Vehicle Systems

Honggu Kang, Jingon Joung, Jinyoung Kim, Joonhyuk Kang, Yong Soo Cho
2020 IEEE Access  
Recognizing the various and broad range of applications of unmanned aerial vehicles (UAVs) and unmanned aircraft systems (UAS) for personal, public and military applications, recent un-intentional malfunctions of uncontrollable UAVs or intentional attacks on them divert our attention and motivate us to devise a protection system, referred to as a counter UAV system (CUS). The CUS, also known as a counterdrone system, protects personal, commercial, public, and military facilities and areas from
more » ... ncontrollable and belligerent UAVs by neutralizing or destroying them. This paper provides a comprehensive survey of the CUS to describe the key technologies of the CUS and provide sufficient information with wich to comprehend this system. The first part starts with an introduction of general UAVs and the concept of the CUS. In the second part, we provide an extensive survey of the CUS through a top-down approach: i) the platform of CUS including ground and sky platforms and related networks; ii) the architecture of the CUS consisting of sensing systems, command-and-control (C2) systems, and mitigation systems; and iii) the devices and functions with the sensors for detection-and-identification and localization-and-tracking actions and mitigators for neutralization. The last part is devoted to a survey of the CUS market with relevant challenges and future visions. From the CUS market survey, potential readers can identify the major players in a CUS industry and obtain information with which to develop the CUS industry. A broad understanding gained from the survey overall will assist with the design of a holistic CUS and inspire cross-domain research across physical layer designs in wireless communications, CUS network designs, control theory, mechanics, and computer science, to enhance counter UAV techniques further. INDEX TERMS Unmanned aerial vehicle (UAV), unmanned aircraft system (UAS), counter UAV system (CUS), counter drone systems, public safety, defense.
doi:10.1109/access.2020.3023473 fatcat:boi4ct6lgvdndp4nhkm2hdthwe

Multi-Channel Packet-Analysis System Based on IEEE 802.15.4 Packet-Capturing Modules

Seong-eun Yoo, Poh Kit Chong, Jeonghwan Bae, Tae-Soo Kim, Hiecheol Kim, Joonhyuk Yoo
2014 International Journal of Distributed Sensor Networks  
Jeonghwan Bae, Tae-Soo Kim, Hiecheol Kim, and Seong-eun Yoo presented a preliminary result of this work at EWSN 2014 demo session [19] .  ... 
doi:10.1155/2014/216504 fatcat:w2bcnlqk2ng7hbwc4atk23na4q

Acquaintances Clustering for Social Relationship-Based Indexing of Digital Photos [chapter]

Jonghak Kim, Taekwon Jang, Joonhyuk Yang, Jung-hee Ryu
2010 IFIP Advances in Information and Communication Technology  
One of the effective ways to manage large collections of digital photos is to tag names of people appearing in those photos. However, the number of people appearing in photo collections may range in the hundreds and the names of tagged people are usually presented in alphabetical order or on a firsttag first-place basis. As a result, it is difficult to quickly search for name tags that a user wishes to find. In order to solve this problem, we developed a digital photo management system that
more » ... matically groups the name tags based on their social relationships. This system was tested on users' own photos against three other comparison interfaces. The average searching time for name tags was significantly faster with our system. Also, the user satisfaction was higher than the others.
doi:10.1007/978-3-642-15231-3_17 fatcat:5thtbno2mbgephhrmbagwty7vq

Buffer layer-less fabrication of high-mobility transparent oxide semiconductor, La-doped BaSnO3 [article]

Anup V. Sanchela, Mian Wei, Joonhyuk Lee, Gowoon Kim, Hyoungjeen Jeen, Bin Feng, Yuichi Ikuhara, Hai Jun Cho, Hiromichi Ohta
2018 arXiv   pre-print
Transparent oxide semiconductors (TOSs) showing both high visible transparency and high electron mobility have attracted great attention towards the realization of advanced optoelectronic devices. La-doped BaSnO3 (LBSO) is one of the most promising TOSs because its single crystal exhibits a high electron mobility. However, in the LBSO films, it is very hard to obtain high mobility due to the threading dislocations, which are originated from the lattice mismatch between the film and the
more » ... . Therefore, many researchers have tried to improve the mobility by inserting a buffer layer. While the buffer layers increased the electron mobilities, this approach leaves much to be desired since it involves a two-step film fabrication process and the enhanced mobility values are still significantly lower than single crystal values. We show herein that the electron mobility of LBSO films can be improved without inserting any buffer layers if the films are grown under highly oxidative ozone (O3) atmospheres. The O3 environments relaxed the LBSO lattice and reduced the formation of Sn2+ states, which are known to suppress the electron mobility in LBSO. The resultant O3-LBSO films showed improved mobility values up to 115 cm2 V-1 s-1, which is among the highest in LBSO films on SrTiO3 substrates and comparable to LBSO films with buffer layers.
arXiv:1808.07619v1 fatcat:lzmtmgfhhjgmxlr3uisooqyfry

Increased threshold in nonselective His-bundle pacing suspected to be caused by amiodarone

JoonHyuk Kim, Seth Goldbarg, Steven Leung, Hua Yang, David Slotwiner
2019 HeartRhythm Case Reports  
doi:10.1016/j.hrcr.2018.11.007 pmid:30820410 pmcid:PMC6379566 fatcat:oxbwx2uy4zecjmdtw2e6eqe6sq

Abnormal Orientation of the Superior Mesenteric Vessels Detected in Asymptomatic Infants: What Is Its Destiny?

Joonhyuk Son, Sanghoon Lee, Wontae Kim, Soo-Min Jung, Tae Yeon Jeon, So-Young Yoo, Ji Hye Kim, Jeong-Meen Seo
2021 Frontiers in Pediatrics  
Ultrasonography (USG) has been described as an alternative diagnostic tool for malrotation that evaluates the orientation of the superior mesenteric vessels. However, literature concerning the management of patients who do not have abdominal symptoms is limited. We aimed to review the clinical course of infants showing abnormal orientation of the superior mesenteric vessels on USG who were asymptomatic at the time of diagnosis.Methods: Seventy asymptomatic infants with abnormal orientation of
more » ... e superior mesenteric vessels in a single center between 2014 and 2018 were retrospectively analyzed.Results: The 70 patients, 21 underwent upper gastrointestinal series (UGIS) and 11 underwent abdominal surgery for other surgical conditions. Among the 32 (45.7%) patients who underwent UGIS or abdominal surgery, 11 were proven to have malrotation. Of the 38 (54.3%) patients who did not undergo UGIS or abdominal surgery, six patients were too unstable to undergo UGIS, five died due to cardiac complications, and the remaining patient developed midgut volvulus and died 3 days after emergency surgery. The remaining 32 patients who did not undergo UGIS or abdominal surgery were discharged without additional tests, and all were asymptomatic until their last follow-up. In the multivariate analysis, history of heart surgery and the presence of more than three anomalies were significantly associated with malrotation.Conclusion: A significant number of malrotation were diagnosed in asymptomatic infants with abnormal orientation of the superior mesenteric vessels on USG. Infants with major cardiac or multiple anomalies need special attention and should undergo UGIS in a promptly manner to confirm malrotation.
doi:10.3389/fped.2021.665448 pmid:34178885 pmcid:PMC8226012 fatcat:464qnaa5zndjnihbxa4i7zn4oa
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