• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.123-125
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• 2006

This paper discusses the method of vision based sensor fusion system for biped robot walking. Most researches on biped walking robot have mostly focused on walking algorithm itself. However, developing vision systems for biped walking robot is an important and urgent issue since biped walking robots are ultimately developed not only for researches but to be utilized in real life. In the research, systems for environment recognition and tole-operation have been developed for task assignment and execution of biped robot as well as for human robot interaction (HRI) system. For carrying out certain tasks, an object tracking system using modified optical flow algorithm and obstacle recognition system using enhanced template matching and hierarchical support vector machine algorithm by wireless vision camera are implemented with sensor fusion system using other sensors installed in a biped walking robot. Also systems for robot manipulating and communication with user have been developed for robot.

• 한국정보통신학회논문지
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• 제10권5호
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• pp.934-941
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• 2006

모바일 기기의 특성상 기기에 많은 영향을 받기 때문에 모바일 데이터서비스 환경에서의 문제점을 나타내었고, 각 회사별로 각각의 에뮬레이터와 API가 나오게 되었는데 서로 다른 에뮬레이터와 API 때문에 CP 업체쪽에서는 특정회사만을 위한 서비스가 아닌 모든 이동회사에게 서비스를 하기 위해 각각의 에뮬레이터로 개발과 테스트를 하고 있는 문제점 때문에 모바일 컨텐츠 변환시스템의 필요성이 대두되고 있다. 본 논문에서는 모바일 컨텐츠 개발시 서로 다른 컨텐츠를 각 회사별로 맞도록 변환시키는 컨텐츠 변환 시스템을 구현하여 막대한 비용을 절감할 수 있도록 하였고, 또한 모바일 데이터서비스 환경에서 XML 문서를 사용하여 데이터의 상호 처리 능력을 향상시키고, 데이터의 공용성과 프로그램의 유연성을 향상시키는데 필요한 비용과 노력을 훨씬 절감할 수 있도록 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2144-2165
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• 2016

In a vehicular ad hoc network, the communication links are unsteady due to the rapidly changing topology, high mobility and traffic density in the urban environment. Most of the existing geographical routing protocols rely on the continuous transmission of beacon messages to update the neighbors' presence, leading to network congestion. Source-based approaches have been proven to be inefficient in the inherently unstable network. To this end, we propose an opportunistic beaconless packet forwarding approach based on a modified handshake mechanism for the urban vehicular environment. The protocol acts differently between intersections and at the intersection to find the next forwarder node toward the destination. The modified handshake mechanism contains link quality, forward progress and directional greedy metrics to determine the best relay node in the network. After designing the protocol, we compared its performance with existing routing protocols. The simulation results show the superior performance of the proposed protocol in terms of packet delay and data delivery ratio in realistic wireless channel conditions.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제9권6호
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• pp.131-136
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• 2020

차량 환경의 통신에서 콘텐츠의 사전 캐싱은 사용자로부터 콘텐츠 서버까지의 지연시간을 감소시킬 수 있다. 하지만 어디에, 어느 량 만큼의 사전 캐싱을 해야하는 지에 대한 문제점은 아직도 해결되지 않고 있다. 본 논문에서는 차량의 이동 확률을 토대로 차량이 다음으로 이동하게 될 기지국 후보들에게 각각 최적화된 량만큼의 콘텐츠를 분산시켜 사전 캐싱하는 방안을 제시한다. 우선, 각 차량의 이동 확률은 Markov Chain을 이용하여 학습되었다. 그리고 분산하여 사전 캐싱할 콘텐츠의 량은 무선 환경을 기반으로 최적화되었다. NS-3를 기반으로 진행된 실험에서 제안방안은 기존 방안에 비하여 최소의 지연시간을 유지하며 트래픽을 가장 많이 절약한 결과가 도출되었다.

• 한국지능시스템학회논문지
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• 제25권5호
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• pp.464-469
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• 2015

본 논문은 방범과 쾌적한 실내 환경 유지를 위한 창호의 상태와 실내외 환경데이터를 수집 분석하여 원격관리하기 위한 스마트 창호시스템 플랫폼을 제안한다. 특히 보안 분야, 안전 분야, 가전기기 제어와 같은 홈서비스를 용이하게 하기 위한 스마트 창호 플랫폼과 스마트 홈 플랫폼 사이 표준 API를 제안한다. 제안된 플랫폼 기반으로 언제 어디에서나 방범 및 환기 등의 문제를 해결할 수 있는 원격 자동개폐 및 감시를 위한 유무선 통신인터페이스의 창호시스템 전용 게이트웨이를 개발하였다. 또한 모바일 환경에서 창호의 개폐 상태 감시 및 원격제어를 위한 웹과 앱 기반 사용자 인터페이스도 각각 개발하였다.

• 대한인간공학회지
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• 제31권4호
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• pp.577-583
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• 2012

Objective: This paper describes the process and results related to the development of gesture recognition-based natural user interface(NUI) for vehicle maintenance e-Training system. Background: E-Training refers to education training that acquires and improves the necessary capabilities to perform tasks by using information and communication technology(simulation, 3D virtual reality, and augmented reality), device(PC, tablet, smartphone, and HMD), and environment(wired/wireless internet and cloud computing). Method: Palm movement from depth camera is used as a pointing device, where finger movement is extracted by using OpenCV library as a selection protocol. Results: The proposed NUI allows trainees to control objects, such as cars and engines, on a large screen through gesture recognition. In addition, it includes the learning environment to understand the procedure of either assemble or disassemble certain parts. Conclusion: Future works are related to the implementation of gesture recognition technology for a multiple number of trainees. Application: The results of this interface can be applied not only in e-Training system, but also in other systems, such as digital signage, tangible game, controlling 3D contents, etc.

• 디지털콘텐츠학회 논문지
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• 제8권4호
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• pp.431-439
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• 2007

현재 초고속으로 발전하는 유비쿼터스(ubiquitous) 환경에서 센서-네트워크를 기반으로 한 u-Campus 구축이 발전하고 있다. 또한 PC, mobile등 그 어떤 정보기기라도 언제 어디서든 컴퓨팅이 가능하며 무선망의 발전으로 서비스 환경은 계속적으로 발전하고 있다. 본 논문에서는 모바일 활용을 이용한 사용자 환경에 적합한 u-Campus를 제안한다. u-Campus는 정보통신 기술의 발전과 더불어 다양한 관련 기술이 교육에도 접목되어 활용되고 있다. 특히 유비쿼터스 컴퓨팅과 네트워크 기술을 대학의 캠퍼스에 접목시켜 구축한 새로운 형태의 캠퍼스가 u-Campus이다. 본 논문에서는 u-Yuhan 설계 방안을 제안하여 학생들의 효율적이고 향상된 학내 활동이 가능하도록 한다.

• 전기학회논문지
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• 제59권11호
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• pp.2108-2113
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• 2010

The Long Term Evolution (LTE) system is based on the Orthogonal Frequency Division Multiplexing (OFDM) and relies its channel estimation on the lattice-type pilot samples in the multipath fading channel environment. The estimation of the channel frequency response (CFR) makes use of the least squares estimate (LSE) for each pilot samples, followed by an interpolation both in time- and in frequency-domain to fill up the channel estimates for subcarriers corresponding to data samples. Any interpolation scheme could be adopted for this purpose. Depending on the requirements of the target system, we may choose a simple linear interpolation or a sophisticated one. For any choice of an interpolation scheme, these is a trade-off between estimation accuracy and numerical cost. For those wireless communication systems based on the OFDM and the preamble-type pilot structure, the DFT-based channel estimation and its variants have been successfully. Yet, it may not be suitable for the lattice-type pilot structure, since the pilot samples are not sufficient to provide an accurate estimate and it is known to be sensitive to the location as well as the length of the time-domain window. In this paper, we propose a simple interpolated based on the upsampling mechanism in the multirate signal processing. The proposed method provides an excellent alternative to the DFT-based methods in terms of numerical cost and accuracy. The performance of the proposed technique is verified on a multipath environment suggested on a 3GPP LTE specification.

• 센서학회지
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• 제21권2호
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• pp.103-108
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• 2012

Radiofrequency(RF) signal is a key medium to the most of the present wireless communication devices including RF identification devices(RFID) and smart sensors. However, the most critical barrier to overcome in RFID application is in the failure rate in detection. The most notable improvement in the detection was from the introduction of EPC Class1 Gen2 protocol, but the fundamental problems in the physical properties of the RF signal drew less attention. In this work, we focused on the physical properties of the RF signal in order to understand the failure rate by noting the existence of the ground planes and noise sources in the real environment. By using the mathematical computation software, Maple, we simulated the distribution of the electromagnetic field from a dipole antenna when ground planes exist. Calculations showed that the dark area can be formed by interference. We also constructed a test system to measure the failure rate in the detection of a RFID transponder. The test system was composed of a fixed RFID reader and an EPC Class1 Gen2 transponder which was attached to a scanner to sweep in the x-y plane. Labview software was used to control the x-y scanner and to acquire data. Tests in the laboratory environment showed that the dark area can be as much as 43 %. One who wants to use RFID and smart sensors should carefully consider the extent of the dark area.

• 한국군사과학기술학회지
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• 제2권2호
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• pp.117-130
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• 1999

In this paper, the performance of data communication function of military radio equipment P-999K is analyzed based on the standard CSMA/CA protocol which is DFWMAC standard protocol done by IEEE802.11 work group. Basic three standard protocols, i.e. Basic CSMA/CA, Stop & Wait ARQ and 4-Way Handshake CSMA/CA protocols are analyzed and compared with each other under the hidden terminal environment. The computer simulation is also done by using SIMSCRIPT II.5 which is popular software tool for an independent processing. The results show that p-persistent(with p=0.3) CSMA scheme is superior to non-persistent CSMA scheme with non-hidden terminal condition, but the performances of both schemes are almost same with hidden terminal situation. And the results of computer simulations are also showed that Basic CSMA/CA protocol is superior to the other protocols when the ratio of hidden terminals is below 10 % of total user population, however, with the above 20% hidden terminals environment and the higher offered traffic conditions the 4-Way Handshake CSMA/CA protocol shows the most superior performance.