• 한국산업융합학회 논문집
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• 제25권6_1호
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• pp.953-959
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• 2022

In this paper, the design result of robotic tools and the development of robot control system for chemical coupler assembly are presented. This research aims to eliminate the risk of chemicals exposed to human operators by developing the robotic tools and robot automation system for chemical tank lorry unloading that were done manually. Due to tight tolerance between couplers, even small pose error may result in very large internal force. In order to resolve the problem, the 6-axis compliance device is employed, which can provide not only enough compliance between couplers but also F/T sensing. The 6-axis compliance device having large force and moment capacity is designed. A simple linear gripper with rack-and-pinion is designed to grasp two sizes of couplers. The proposed robot automation system consists of 6-DOF collaborative robot with offset wrist, 6-axis compliance device with F/T sensing, linear gripper, and two robot visions.

• Journal of Communications and Networks
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• 제18권5호
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• pp.784-795
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• 2016

In this paper, we investigate the resource allocation problem in time-varying heterogeneous wireless networks (HetNet) with multi-homing user equipments (UE). The stochastic optimization model is employed to maximize the network utility, which is defined as the difference between the HetNet's throughput and the total energy consumption cost. In harmony with the hierarchical architecture of HetNet, the problem of stochastic optimization of resource allocation is decomposed into two subproblems by the Lyapunov optimization theory, associated with the flow control in transport layer and the power allocation in physical (PHY) layer, respectively. For avoiding the signaling overhead, outdated dynamic information, and scalability issues, the distributed resource allocation method is developed for solving the two subproblems based on the primal-dual decomposition theory. After that, the adaptive resource allocation algorithm is developed to accommodate the timevarying wireless network only according to the current network state information, i.e. the queue state information (QSI) at radio access networks (RAN) and the channel state information (CSI) of RANs-UE links. The tradeoff between network utility and delay is derived, where the increase of delay is approximately linear in V and the increase of network utility is at the speed of 1/V with a control parameter V. Extensive simulations are presented to show the effectiveness of our proposed scheme.

• International Journal of Knowledge Content Development & Technology
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• 제12권3호
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• pp.31-49
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• 2022

The study presents a global research scenario in the domain of quantum sensing in quantitative and qualitative terms. The study is based on an analysis of 588 global publications in the field, sourced from the Scopus database for the period 1991-2020. The study identified key countries, organizations and authors, network collaborative linkages at national, institutional, and author level. In addition, it identified broad subject areas intersecting quantum sensing research, key journals for research communications, and broad characteristics of highly-cited papers. The study finds that the USA and Germany lead the world ranking in quantum sensing research with a combined share of 50% to the global output. The USA, Germany, and Italy are the home countries to 13 of the top 15 most productive organizations, and also the home countries to 14 of the top 15 most productive authors in the subject. The top journals publishing most research publications are Physical Review A, Physical Review Letters and New Journal of Physics. However, in the most cited journals list in the subject, Agriculture & Forest Meterology, Science and Physical Review A tops the list.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2006년도 추계 종합학술대회 논문집
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• pp.616-621
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• 2006

최근에 인간과 컴퓨터 상호작용을 위한 사용자 의도 및 행위 인식에 관한 비전 기반 연구가 활발히 진행되고 있다. 그 중에서도 테이블-탑 디스플레이 시스템은 터치 감지 기술의 발전, 협력적인 작업 추구에 발맞추어 다양한 응용으로 발전하였다. 이전의 테이블-탑 디스플레이는 오직 한명의 사용자만을 지원하였으나 현재에는 멀티터치를 통한 멀티유저를 지원하게 되었다. 따라서 테이블-탑 디스플레이의 궁극적인 목적인 협력적인 작업과 네 가지 원소 (인간, 컴퓨터, 투영된 객체, 물리적 객체)의 상호작용이 실현 가능하게 되었다. 일반적으로 테이블-탑 디스플레이 시스템은 다음의 네 가지 요소; 맨 손을 이용한 멀티터치 상호작용, 동시적인 사용자 상호작용을 통한 협력적인 작업의 구현, 임의의 위치 터치를 이용한 정보 조작, 상호작용의 도구로서 물리적인 객체의 사용을 중심으로 설계되어 있다. 본 논문에서는 테이블-탑 디스플레이 시스템을 위한 최첨단의 멀티터치 센싱 기술을 시각기반 방법, 비-시각 기반 방법으로 분류하고 비판적인 견해에서 분석을 하였다. 또한 테이블-탑 디스플레이 관련 연구들을 시스템 구성방식에 따라 분류하고 그 장단점과 실제 사용되는 응용 분야에 대해 기술하였다.

• 한국콘텐츠학회논문지
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• 제7권2호
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• pp.84-91
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• 2007

최근에 인간과 컴퓨터 상호작용을 위한 사용자 의도 및 행위 인식에 관한 비전 기반 연구가 활발히 진행되고 있다. 그 중에서도 테이블-탑 디스플레이 시스템은 터치 감지 기술의 발전, 협력적인 작업 추구에 발맞추어 다양한 응용으로 발전하였다. 이전의 테이블-탑 디스플레이는 오직 한 명의 사용자만을 지원하였으나 현재에는 멀티터치를 통한 멀티유저를 지원하게 되었다. 따라서 테이블-탑 디스플레이의 궁극적인 목적인 협력적인 작업과 네 가지 원소 (인간, 컴퓨터, 투영된 객체, 물리적 객체) 의 상호작용이 실현 가능하게 되었다. 일반적으로 테이블-탑 디스플레이 시스템은 다음의 네 가지 측면; 맨 손을 이용한 멀티 터치 상호작용, 동시적인 사용자 상호작용을 통한 협력적인 작업의 구현, 임의의 위치 터치를 이용한 정보 조작, 상호작용의 도구로서 물리적인 객체의 사용을 중심으로 설계되어 있다. 본 논문에서는 테이블-탑 디스플레이 시스템을 위한 최첨단의 멀티터치 센싱 기술을 시각기반 방법, 비-시각 기반 방법으로 분류하고 비판적인 견해에서 분석을 하였다. 또한 테이블-탑 디스플레이 관련 연구들을 시스템 구성방식에 따라 분류하고 그 장단점과 실제 사용되는 응용 분야에 대해 기술하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4661-4680
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• 2016

Cognitive radio (CR) technology is an effective solution to the spectrum scarcity issue. Collaborative spectrum sensing is known as a promising technique to improve the performance of spectrum sensing in cognitive radio networks (CRNs). However, collaborative spectrum sensing is vulnerable to spectrum data falsification (SSDF) attack, where malicious users (MUs) may send false sensing data to mislead other secondary users (SUs) to make an incorrect decision about primary user (PUs) activity, which is one of the key adversaries to the performance of CRNs. In this paper, we propose a coalition based malicious users detection (CMD) algorithm to detect the malicious user in CRNs. The proposed CMD algorithm can efficiently detect MUs base on the Geary'C theory and be modeled as a coalition formation game. Specifically, SSDF attack is one of the key issues to affect the resource allocation process. Focusing on the security issues, in this paper, we analyze the power allocation problem with MUs, and propose MUs detection based power allocation (MPA) algorithm. The MPA algorithm is divided into two steps: the MUs detection step and the optimal power allocation step. Firstly, in the MUs detection step, by the CMD algorithm we can obtain the MUs detection probability and the energy consumption of MUs detection. Secondly, in the optimal power allocation step, we use the Lagrange dual decomposition method to obtain the optimal transmission power of each SU and achieve the maximum utility of the whole CRN. Numerical simulation results show that the proposed CMD and MPA scheme can achieve a considerable performance improvement in MUs detection and power allocation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권7호
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• pp.1951-1975
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• 2023

Recent advances in Cognitive Radio Networks (CRN) have elevated them to the status of a critical instrument for overcoming spectrum limits and achieving severe future wireless communication requirements. Collaborative spectrum sensing is presented for efficient channel selection because spectrum sensing is an essential part of CRNs. This study presents an innovative cooperative spectrum sensing (CSS) model that is built on the Firefly Algorithm (FA), as well as machine learning artificial neural networks (ANN). This system makes use of user grouping strategies to improve detection performance dramatically while lowering collaboration costs. Cooperative sensing wasn't used until after cognitive radio users had been correctly identified using energy data samples and an ANN model. Cooperative sensing strategies produce a user base that is either secure, requires less effort, or is faultless. The suggested method's purpose is to choose the best transmission channel. Clustering is utilized by the suggested ANN-FA model to reduce spectrum sensing inaccuracy. The transmission channel that has the highest weight is chosen by employing the method that has been provided for computing channel weight. The proposed ANN-FA model computes channel weight based on three sets of input parameters: PU utilization, CR count, and channel capacity. Using an improved evolutionary algorithm, the key principles of the ANN-FA scheme are optimized to boost the overall efficiency of the CRN channel selection technique. This study proposes the Artificial Neural Network with Firefly Algorithm (ANN-FA) for cognitive radio networks to overcome the obstacles. This proposed work focuses primarily on sensing the optimal secondary user channel and reducing the spectrum handoff delay in wireless networks. Several benchmark functions are utilized We analyze the efficacy of this innovative strategy by evaluating its performance. The performance of ANN-FA is 22.72 percent more robust and effective than that of the other metaheuristic algorithm, according to experimental findings. The proposed ANN-FA model is simulated using the NS2 simulator, The results are evaluated in terms of average interference ratio, spectrum opportunity utilization, three metrics are measured: packet delivery ratio (PDR), end-to-end delay, and end-to-average throughput for a variety of different CRs found in the network.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.37-43
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• 2012

본 논문은 광대역 센싱을 수행하기 위한 방법으로 다중 협대역을 사용하여 한번에 센싱하는 방법을 제안한다. 센싱의 신뢰성을 높이기 위한 방안으로써 면허사용자와 CR사용자의 거리에 따른 가중치가 적용된 결합방식인(DWC : Distance based weight combining) 기법을 사용한 에너지 검출 기반 협력 스펙트럼 센싱을 제안하고 이에 따른 시스템 모델의 모의 실험 결과를 분석한다. 면허 사용자와 CR사용자 사이의 무선 채널은 가우시안 채널로 모델링하였다. 에너지 검출법을 위한 임계값은 각 채널의 SNR(Signal to Noise Ratio)에 따라 다르게 적용 되고, 각 채널의 잡음 신호의 평균값으로 가정한다.

• ETRI Journal
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• 제39권1호
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• pp.30-40
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• 2017

In this study, we investigate topology control as a means of obtaining the best possible compromise between the conflicting requirements of reducing energy consumption and improving network connectivity. A topology design algorithm capable of producing network topologies that minimize energy consumption under a minimum-connectivity constraint is presented. To this end, we define a new topology metric, called connectivity efficiency, which is a function of both algebraic connectivity and the transmit power level. Based on this metric, links that require a high transmit power but only contribute to a small fraction of the network connectivity are chosen to be removed. A connectivity-efficiency-based topology control (CETC) algorithm then assigns a transmit power level to each node. The network topology derived by the proposed CETC heuristic algorithm is shown to attain a better tradeoff between energy consumption and network connectivity than existing algorithms. Simulation results demonstrate the efficiency of the CECT algorithm.

• 전자공학회논문지CI
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• 제44권5호
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• pp.49-56
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• 2007

센서네트워크에서 신호처리를 수행하는 경우 노이즈 감쇄문제는 우선적으로 해결되어야 할 과제이다. 센서노드가 수집한 데이터에 포함된 노이즈가 센서네트워크의 신호처리 결과에 악영향을 미치는 것은 자명하다. 본 논문에서는 무선센서네트워크에서 사용할 수 있는 노이즈 감쇄 필터를 제안한다. 제안된 필터는 센서노드간의 상대적인 거리정보만을 사용하여 동작하며 구성이 단순하며 구현도 쉽다. 또한 센서노드의 통신반경을 적절한 범위에서 조정하여 전력소모를 줄이고 전체 네트워크의 수명을 연장할 수 있다. 다양한 조건에 대하여 성능평가를 수행하여 제안된 필터가 수집된 데이터에 대한 노이즈 영향을 감소시키는 것을 확인 하였다.