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Dynamic adaptation of contention window for consumer devices in WiMedia home networks
Hyunhee Park,Sangheon Pack,Chul-Hee Kang IEEE 2011 IEEE TRANSACTIONS ON CONSUMER ELECTRONICS - Vol.57 No.1
<P>WiMedia ultra-wideband technology is an attractive transmission solution for high-data-rate multimedia streaming and high-quality consumer electronic devices in wireless multimedia home networks. However, the contention-based protocol of WiMedia medium access control (MAC) may cause channel collisions and throughput degradation as the number of consumer devices in the network increases. In order to resolve this problem and to reduce channel access latency, we propose a dynamic adaptation of contention window (DACW) scheme in which the contention window size for the optimal transmission probability is derived after traffic information has been obtained by means of distributed beaconing procedures. The trace-driven simulation results demonstrate that the DACW scheme outperforms the existing channel access schemes (i.e., prioritized channel access) in WiMedia MAC under different situations, especially when the number of contending nodes is large.</P>
Density-Based Opportunistic Broadcasting Protocol for Emergency Situations in V2X Networks
Park, Hyunhee,Singh, Kamal Deep,Piamrat, Kandaraj The Korea Institute of Information and Commucation 2014 Journal of information and communication convergen Vol.12 No.1
Vehicular-to-anything (V2X) technology is attractive for wireless vehicular ad-hoc networks (VANETs) because it allows for opportunistic choice of a vehicular protocol between vehicular-to-vehicular (V2V) and vehicular-to-infrastructure (V2I) communications. In particular, achieving seamless connectivity in a VANET with nearby network infrastructure is challenging. In this paper, we propose a density-based opportunistic broadcasting (DOB) protocol, in which opportunistic connectivity is carried out by using the nearby infrastructure and opposite vehicles for solving the problems of disconnection and long end-to-end delay times. The performance evaluation results indicate that the proposed DOB protocol outperforms the considered comparative conventional schemes, i.e., the shortest path protocol and standard mobile WiMAX, in terms of the average end-to-end delay, packet delivery ratio, handover latency, and number of lost packets.
Park, Hyunhee,Chung, Kyung Min,An, Hyun-Kyu,Gim, Ji-Eun,Hong, Jihyun,Woo, Hanwoong,Cho, Bongki,Moon, Cheil,Yu, Seong-Woon Frontiers Media S.A. 2019 Frontiers in molecular neuroscience Vol.12 No.-
<P>Regulated cell death (RCD) plays a fundamental role in human health and disease. Apoptosis is the best-studied mode of RCD, but the importance of other modes has recently been gaining attention. We have previously demonstrated that adult rat hippocampal neural stem (HCN) cells undergo autophagy-dependent cell death (ADCD) following insulin withdrawal. Here, we show that Parkin mediates mitophagy and ADCD in insulin-deprived HCN cells. Insulin withdrawal increased the amount of depolarized mitochondria and their colocalization with autophagosomes. Insulin withdrawal also upregulated both mRNA and protein levels of Parkin, gene knockout of which prevented mitophagy and ADCD. c-Jun is a transcriptional repressor of Parkin and is degraded by the proteasome following insulin withdrawal. In insulin-deprived HCN cells, Parkin is required for Ca<SUP>2+</SUP> accumulation and depolarization of mitochondria at the early stages of mitophagy as well as for recognition and removal of depolarized mitochondria at later stages. In contrast to the pro-death role of Parkin during mitophagy, Parkin deletion rendered HCN cells susceptible to apoptosis, revealing distinct roles of Parkin depending on different modes of RCD. Taken together, these results indicate that Parkin is required for the induction of ADCD accompanying mitochondrial dysfunction in HCN cells following insulin withdrawal. Since impaired insulin signaling is implicated in hippocampal deficits in various neurodegenerative diseases and psychological disorders, these findings may help to understand the mechanisms underlying death of neural stem cells and develop novel therapeutic strategies aiming to improve neurogenesis and survival of neural stem cells.</P>
Hyunhee Joo,Woonhee Baek,Chanmi Park,Sung Chul Lee 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07
A pepper bZIP transcription factor gene, CabZIP2, was isolated from pepper leaves infected with an a virulent strain of Xanthomonas campestris pv. vesicatoria (Xcv). Transient expression analysis of the CabZIP2-GFP fusion protein in Nicotiana benthamiana revealed that the CabZIP2 protein is localized in the cytoplasm as well as the nucleus. The acidic domain in the N-terminal region of CabZIP2 that is fused to the GAL4 DNA-binding domain is required to activate the transcription of reporter genes in yeast. Transcription of CabZIP2 is induced in pepper plants inoculated with virulent or avirulent strains of Xcv. The CabZIP2 gene is also induced by defense-related hormones such as salicylic acid, methyl jasmonate, and ethylene. To elucidate the in vivo function of the CabZIP2 gene in plant defense, virus-induced gene silencing (VIGS) in pepper and overexpression in Arabidopsis were used. CabZIP2-silenced pepper plants were susceptible to infection by the virulent strain of Xcv, which was accompanied by reduced expression of defense-related genes such as CaBPR1 and CaAMP1. CabZIP2 overexpression (OX) in transgenic Arabidopsis plants conferred enhanced resistance to Pseudomonas syringae pv. tomato DC3000. Together, these results suggest that CabZIP2 is involved in bacterial disease resistance.
Second hand smoke exposure in workplace by job status and occupations
Hyunhee Park,Sung-il Cho,Changhun Lee 대한직업환경의학회 2019 대한직업환경의학회지 Vol.31 No.-
Background: The objective of this study is to evaluate the risk of exposure to second hand smoke (SHS) during working hours by job status and occupation. Methods: Using the 4th Korean Working Conditions Survey (KWCS), 49,674 respondents who answered the question about SHS were studied. A chi-square test was carried out to determine whether there is a significant different in SHS exposure frequency by general and occupational characteristics and experience of discrimination at work and logistic regression analysis was carried out to identify the risk level of SHS exposure by variables. Results: In this study, we found that male workers in their 40s and 50s, workers employed in workplaces with fewer than 50 employees, daily workers, and people working outdoors had a higher rate of exposure to SHS than the others. The top five occupations with the highest SHS exposure were construction and mining-related occupations, metal core-makers-related trade occupations, wood and furniture, musical instrument, and signboardrelated trade occupations, transport and machine-related trade occupations, transport and leisure services occupations. The least five exposed occupations were public and enterprise senior officers, legal and administrative professions, education professionals, and health, social welfare, and religion-related occupations. Conclusion: Tobacco smoke is a significant occupational hazard. Smoking ban policy in the workplace can be a very effective way to reduce the SHS exposure rate in the workplace and can be more effective if specifically designed by the job status and various occupations.
Concurrent Channel Time Allocation for Resource Management in WPANs
Park, Hyunhee,Piamrat, Kandaraj,Singh, Kamal Deep The Korea Institute of Information and Commucation 2014 Journal of information and communication convergen Vol.12 No.2
This paper presents a concurrent channel time allocation scheme used in the reservation period for concurrent transmissions in 60-GHz wireless personal area networks (WPANs). To this end, the proposed resource allocation scheme includes an efficient method for creating a concurrent transmission group by using a table that indicates whether individual streams experience interference from other streams or not. The coordinator device calculates the number of streams that can be concurrently transmitted with each stream and groups them together on the basis of the calculation result. Then, the coordinator device allocates resources to each group such that the streams belonging to the same group can transmit data concurrently. Therefore, when the piconet coordinator (PNC) allocates the channel time to the individual groups, it should allow for maximizing the overall capacity. The performance evaluation result demonstrates that the proposed scheme outperforms the random grouping scheme in terms of the overall capacity when the beamwidth is $30^{\circ}C$ and the radiation efficiency is 0.9.
The pepper RING finger protein CaRING1 plays a role in abscisic acid signaling and drought tolerance
Hyunhee Joo,Woonhee Baek,Chanmi Park,Sung Chul Lee 한국육종학회 2015 한국육종학회 심포지엄 Vol.2015 No.07
Plants are constantly exposed to a variety of biotic and abiotic stresses, which include pathogens and conditions of high salinity, low temperature, and drought. Abscisic acid (ABA) is a major plant hormone involved in signal transduction pathways that mediate the defense response of plants to abiotic stress. Previously, we isolated Ring finger protein gene (CaRING1) frompepper(Capsicum annuum), which is associated with resistance to bacterial pathogens, accompanied by hypersensitive cell death. Here, we report a new function of the CaRING1 gene product in the ABA-mediated defense responses of plants to drought stress. The expression of the CaRING1 gene was induced in pepper leaves treated with ABA or exposed to drought or NaCl. CaRING1-overexpressing (OX) transgenic plants showed enhanced sensitivity to ABA during the seedling growth and establishment. Furthermore, these plants were more tolerant to drought stress than the wild-type plants because of enhanced stomatal closure and increased expression of stress-responsive genes. Together, these results suggest that the CaRING1 acts as positive factor for drought tolerance in Arabidopsis by modulating ABA-mediated stomatal closing and gene expression.
An Incremental Multicast Grouping Scheme for mmWave Networks with Directional Antennas
Hyunhee Park,Seunghyun Park,Taewon Song,Sangheon Pack IEEE 2013 IEEE COMMUNICATIONS LETTERS Vol.17 No.3
<P>In millimeter wave wireless networks with directional antennas, the design of efficient multicast communications is one of the most challenging issues. In this letter, we propose an incremental multicast grouping (IMG) scheme where adaptive beamwidths are generated depending on the locations of multicast devices to maximize the sum rate of devices. We develop a simulator based on the IEEE 802.11ad MAC protocol. Simulation results demonstrate that the IMG scheme can improve the overall throughput by 28% to 79% compared with the conventional multicast schemes.</P>