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| 1 | Optimal Cooperative Spectrum Sensing Based on Butterfly Optimization Algorithm显示文摘Since the introduction of the Internet of Things(IoT),several researchers have been exploring its productivity to utilize and organize the spectrum assets.Cognitive radio(CR)technology is characterized as the best aspirant for wireless communications to augment IoT competencies.In the CR networks,secondary users(SUs)opportunistically get access to the primary users(PUs)spectrum through spectrum sensing.The multipath issues in the wireless channel can fluster the sensing ability of the individual SUs.Therefore,several cooperative SUs are engaged in cooperative spectrum sensing(CSS)to ensure reliable sensing results.In CSS,security is still a major concern for the researchers to safeguard the fusion center(FC)against abnormal sensing reports initiated by the malicious users(MUs).In this paper,butterfly optimization algorithm(BOA)-based soft decision method is proposed to find an optimized weighting coefficient vector correlated to the SUs sensing notifications.The coefficient vector is utilized in the soft decision rule at the FC before making any global decision.The effectiveness of the proposed scheme is compared for a variety of parameters with existing schemes through simulation results.The results confirmed the supremacy of the proposed BOA scheme in both the normal SUs’environment and when lower and higher SNRs information is carried by the different categories of MUs. | Noor Gul Saeed Ahmed Atif Elahi Su Min Kim Junsu Kim | 2022 | Computers, Materials & Continua2022，，4： | 1 |
| 2 | Three-dimensionalization via control of laser-structuring parameters for high energy and high power lithium-ion battery under various operating con ditions显示文摘Laser-structuring is an effective method to promote ion diffusion and improve the performance of lithium-ion battery(LIB)electrodes.In this work,the effects of laser structuring parameters(groove pitch and depth)on the fundamental characteristics of LIB electrode,such as interfacial area,internal resistances,material loss and electrochemical performance,are investigated,LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathodes were structured by a femtosecond laser by varying groove depth and pitch,which resulted in a material loss of 5%-14%and an increase of 140%-260%in the in terfacial area between electrode surface and electrolyte.It is shown that the importance of groove depth and pitch on the electrochemical performance(specific capacity and areal discharge capacity)of laser-structured electrode varies with current rates.Groove pitch is more im porta nt at low current rate but groove depth is at high curre nt rate.From the mapping of lithium concentration within the electrodes of varying groove depth and pitch by laser-induced breakdown spectroscopy,it is verified that the groove functions as a diffusion path for lithium ions.The ionic,electronic,and charge transfer resistances measured with symmetric and half cells showed that these internal resistances are differently affected by laser structuring parameters and the changes in porosity,ionic diffusion and electronic pathways.It is demonstrated that the laser structuring parameters for maximum electrode performance and minimum capacity loss should be determined in consideration of the main operating conditions of LIBs. | Junsu Park Hyeongi Song Inseok Jang Jaepil Lee Jeongwook Um Seong-guk Bae Jihun Kim Sungho Jeong Hyeong-Jin Kim | 2022 | Journal of Energy Chemistry2022，31，1： | 1 |
| 3 | Fast and Robust Face Detec- tion Using Evolutionary Pruning显示文摘 | Junsu Jang JongHwan Kim | | 0，，05： | 1 |
| 4 | Solid-state phase transformations toward a metal-organic framework of 7-connected Zn_(4)0 secondary building units显示文摘In the development of metal-organic frameworks(MOFs),secondary building units(SBUs)have been utilized as molecular modules for the construction of nanoporous materials with robust structures.Under solvothermal synthetic conditions,dynamic changes in the metal coordination environments and ligand coordination modes of SBUs determine the resultant product structures.Alternatively,MOF phases with new topologies can also be achieved by post-synthetic treatment of as-synthesized MOFs via the introduction of acidic or basic moieties that cause the simultaneous cleavage/reformation of coordination bonds in the solid state.In this sense,we studied the solid-state transformation of two ndc-based Zn-MOFs(ndc=1,4-naphthalene dicarboxylate)with different SBUs but the same pcu topology to another MOF with sev topology.One of the chosen MOFs with pcu nets is[Zn_(2)(ndc)_(2)(bpy)]_(n)(bpy=4,4,-bipyridine),(6C_(bpy)-MOF)consisting of a 6-connected pillared-paddlewheel SBU,and the other is IRMOF-7 composed of 6-connected Zn40(C 00)6 SBUs and ndc.Upon post-structural modification,these pcu MOFs were converted into the same MOF with sev topology constructed from the uncommon 7-connected Zri_(4)O(COO)_(7)SBU(7C-MOF).The appropriate post-synthetic conditions for the transformation of each SBUs were systematically examined.In addition,the effect of the pillar molecules in the pillared-paddlewheel MOFs on the topology conversion was studied in terms of the linker basicity,which determines the inertness during the solid-state phase transformation.This post-synthetic modification approach is expected to expand the available methods for designing and synthesizing MOFs with controlled topologies. | Jaehui Kim Junsu Ha Jae Hwa Lee Hoi Ri Moon | 2021 | Nano Research2021，14，2： | 1 |
| 5 | A synthesis of gra- phene/Co3O4thin films for lithium ion battery an- odes by coelectrodeposition 显示文摘 | Gil-Pyo Kim Inho Nam Nam Dong Kim Junsu Park Soomin Park Jongheop Yi | 2012 | Electrochemistry Communications2012，2，2： | 1 |
| 6 | Reconfigurable Sensing Time in Cooperative Cognitive Network Using Machine Learning显示文摘A cognitive radio network(CRN)intelligently utilizes the available spectral resources by sensing and learning from the radio environment to maximize spectrum utilization.In CRNs,the secondary users(SUs)opportunistically access the primary users(PUs)spectrum.Therefore,unambiguous detection of the PU channel occupancy is the most critical aspect of the operations of CRNs.Cooperative spectrum sensing(CSS)is rated as the best choice for making reliable sensing decisions.This paper employs machinelearning tools to sense the PU channels reliably in CSS.The sensing parameters are reconfigured to maximize the spectrum utilization while reducing sensing error and cost with improved channel throughput.The fine-k-nearest neighbor algorithm(FKNN),employed in this paper,estimates the number of samples based on the nature of the channel under-specific detection and false alarm probability demands.The simulation results reveal that the sensing cost is suppressed by reducing the sensing time and exploiting the traditional fusion rules,validating the effectiveness of the proposed scheme.Furthermore,the global decision made at the fusion center(FC)based on the modified sensing samples,results low energy consumption,higher throughput,and improved detection with low error probabilities. | Noor Gul Saeed Ahmed Su Min Kim Muhammad Sajjad Khan Junsu Kim | 2023 | Computers, Materials & Continua2023，，3： | 0 |
| 7 | Energy-Efficient Scheduling for a Cognitive IoT-Based Early Warning System显示文摘Flash floods are deemed the most fatal and disastrous natural hazards globally due to their prompt onset that requires a short prime time for emergency response.Cognitive Internet of things(CIoT)technologies including inherent characteristics of cognitive radio(CR)are potential candidates to develop a monitoring and early warning system(MEWS)that helps in efficiently utilizing the short response time to save lives during flash floods.However,most CIoT devices are battery-limited and thus,it reduces the lifetime of the MEWS.To tackle these problems,we propose a CIoTbased MEWS to slash the fatalities of flash floods.To extend the lifetime of the MEWS by conserving the limited battery energy of CIoT sensors,we formulate a resource assignment problem for maximizing energy efficiency.To solve the problem,at first,we devise a polynomial-time heuristic energyefficient scheduler(EES-1).However,its performance can be unsatisfactory since it requires an exhaustive search to find local optimum values without consideration of the overall network energy efficiency.To enhance the energy efficiency of the proposed EES-1 scheme,we additionally formulate an optimization problem based on a maximum weight matching bipartite graph.Then,we additionally propose a Hungarian algorithm-based energy-efficient scheduler(EES-2),solvable in polynomial time.The simulation results show that the proposed EES-2 scheme achieves considerably high energy efficiency in the CIoT-based MEWS,leading to the extended lifetime of the MEWS without loss of throughput performance. | Saeed Ahmed Noor Gul Jahangir Khan Junsu Kim Su Min Kim | 2022 | Computers, Materials & Continua2022，，6： | 0 |
| 8 | An Intelligent Hybrid Mutual Authentication Scheme for Industrial Internet of Thing Networks显示文摘Internet of Things(IoT)network used for industrial management is vulnerable to different security threats due to its unstructured deployment,and dynamic communication behavior.In literature various mechanisms addressed the security issue of Industrial IoT networks,but proper maintenance of the performance reliability is among the common challenges.In this paper,we proposed an intelligent mutual authentication scheme leveraging authentication aware node(AAN)and base station(BS)to identify routing attacks in Industrial IoT networks.The AAN and BS uses the communication parameter such as a route request(RREQ),node-ID,received signal strength(RSS),and round-trip time(RTT)information to identify malicious devices and routes in the deployed network.The feasibility of the proposed model is validated in the simulation environment,where OMNeT++was used as a simulation tool.We compare the results of the proposed model with existing field-proven schemes in terms of routing attacks detection,communication cost,latency,computational cost,and throughput.The results show that our proposed scheme surpasses the previous schemes regarding these performance parameters with the attack detection rate of 97.7%. | Muhammad Adil Jehad Ali Muhammad Sajjad Khan Junsu Kim Ryan Alturki Mohammad Zakarya Mukhtaj Khan Rahim Khan Su Min Kim | 2021 | Computers, Materials & Continua2021，，7： | 0 |
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