• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.331-333
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• 2015

사물인터넷에 대한 연구가 활발해지면서 많은 분야에 접목이 시작되면서, 스마트 홈 자동화에 대한 관심도 새롭게 확대되고 있다. 본 논문에서는, SmartX-mini 로 호칭하는 소형 IoT-Cloud 테스트베드를 활용하여, 스마트 홈 자동화의 일례로 집 내부 문들의 정보를 실시간으로 확인하는 스마트 도어 서비스를 빠르고 효율적으로 시험적으로 구현해 본다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.73-74
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• 2015

IoT의 발달로 인해 새롭게 빅데이터와 그의 실시간 처리의 중요성이 증대되고 있다. 본 논문에서는 사물인터넷의 관제 및 데이터 처리 기능을 갖춘 SmartX-mini 센터를 통하여 NUC 클러스터의 빅데이터 처리 가능성을 제시하고, 이를 검증하기 위하여 SmartX-mini 테스트베드를 활용한다. SmartX-mini Center의 Spark 프레임워크를 이용한 실험을 통해 IoT 환경에서의 NUC 클러스터의 빅데이터 처리 가능에 대한 가능성을 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.75-77
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• 2015

최근 사물인터넷 패러다임에 맞춰 많은 연구가 진행되고 있으나 대부분이 특정 임베디드 플랫폼들에 집중되고 있다. 본 논문에서는 사물인터넷을 위한 장치들과 네트워크를 관제하는 SmartX-mini 센터를 통한 자원수준 (resource-level) 모니터링 기능을 시험적으로 시도하며, 이를 검증하기 위해 SmartX-mini 테스트베드를 활용한다. 모니터링 기능에 대한 기초적인 설계를 바탕으로 구현된 기능들의 검증하여 사용자들에게 제공하는 편의를 확인하였다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.402-402
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• 2006

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.2043-2046
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• 2002

This paper studies on Sun interference effects or Sun outage effects on C-band satellite reception signal for THAICOM2. The THAICOM2 satellite is at 78.5 degree East 〔co-located with THAICOM3〕. The down link station was located in Khon-kaen, longitude 102.83 degree East and latitude 16.43 degree North. The antenna diameter is 4.6 meters for C-band downlink station. Total 9 times of sun interference events were occurred during summer and fall of 2001 and these about 53 minutes altogether. The Maximum CM degradation of the THAICOM2 system was around 11 dB. The Sun interference events of 53 minutes of one year are 0.0122 percents of the C-band contact time when 21 hours of contact time is used f3r broadcasting a day.

• Journal of Positioning, Navigation, and Timing
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• v.1 no.1
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• pp.65-75
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• 2012

We carry out an error analysis of 24-hour global positioning system (GPS)-very long baseline interferometry (VLBI) (GV) hybrid observation data. In this paper, we focus on the impacts of broadcast and final orbits on the GPS delays of the GV hybrid observation by analyzing the residuals, observed - calculated (O-C) values. The residuals show apparent and consistent biases for L1 and L2 signals, respectively. The scatters of the residuals are around a few nanoseconds. The main cause of those observation errors is the absence of the GPS phase and delay calibration system. Most of the satellites show that the differences between the delays, to which broadcast and final orbits are applied, are about 100 times smaller than the current GV hybrid observation errors. We conclude that GPS delays are not greatly affected by orbit accuracies.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1945-1948
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• 2004

This paper describes the design and construction of a micro robotic system addressing such important aspects as versatility and low cost for rapid development and test of new control algorithm. The design and structure of micro robots are presented in detail. The supervision oriented concept is designed for controlling a group of micro robots. In this concept, the vision system recognizes the environment and the host computer decides the micro robot action based on the information from the vision system. In addition, the micro robots can be implemented cheaply and small in size because the structure of supervision oriented system is simplest. The experimental results and the performance of the proposed micro robotic system are discussed.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.364-374
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• 2016

With vast amounts of spectrum available in the millimeter wave (mmWave) band, small cells at mmWave frequencies densely deployed underlying the conventional homogeneous macrocell network have gained considerable interest from academia, industry, and standards bodies. Due to high propagation loss at higher frequencies, mmWave communications are inherently directional, and concurrent transmissions (spatial reuse) under low inter-link interference can be enabled to significantly improve network capacity. On the other hand, mmWave links are easily blocked by obstacles such as human body and furniture. In this paper, we develop a multi-hop relaying transmission (MHRT) scheme to steer blocked flows around obstacles by establishing multi-hop relay paths. In MHRT, a relay path selection algorithm is proposed to establish relay paths for blocked flows for better use of concurrent transmissions. After relay path selection, we use a multi-hop transmission scheduling algorithm to compute near-optimal schedules by fully exploiting the spatial reuse. Through extensive simulations under various traffic patterns and channel conditions, we demonstrate MHRT achieves superior performance in terms of network throughput and connection robustness compared with other existing protocols, especially under serious blockage conditions. The performance ofMHRT with different hop limitations is also simulated and analyzed for a better choice of the maximum hop number in practice.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.784-787
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• 1999

This paper describes a direct digital frequency synthesizer using the CORDIC algorithm, which can be implemented efficiently for a digital sinusoid synthesis. To optimize the hardware design parameters, we perform numerical analysis of the quantization effects for the CORDIC-based architecture. A pipelined architecture is employed to obtain a high data throughput,. We estimate and summarize its hardware costs for a variable accuracy, and a CORDIC-based architecture for 9 bit accuracy is emulated in FPGA.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.414-416
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• 2000

We investigate potential advantages and problems when a superscalar processor is designed and implemented using asynchronous design methods. Conventional techniques of superscalar processing are applied and data dependent adder is considered as an asynchronous component. Intensive simulations on SPEC INT95 benchmark suites are made for the purpose of performance comparison between a synchronous and an asynchronous superscalar processor, respectively. The simulation results show about 5% speedup with asynchronous design methods in the sense of Issue Rate.