• 제어로봇시스템학회논문지
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• 제22권8호
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• pp.671-677
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• 2016

A Controller Area Network (CAN) is a serial communication protocol that is highly reliable and efficient in many aspects, such as wiring cost and space, system flexibility, and network maintenance. Therefore, it is chosen for the communication protocol between a single chip controller based on Field Programmable Gate Array (FPGA) and peripheral devices. In this paper, the design and implementation of CAN IP, which is written in VHSIC Hardware Description Language (VHDL), is presented. The implemented CAN IP is based on the CAN 2.0A specification. The CAN IP consists of three processes: clock generator, bit timing, and bit streaming. The clock generator process generates a time quantum clock. The bit timing process does synchronization, receives bits from the Rx port, and transmits bits to the Tx port. The bit streaming process generates a bit stream, which is made from a message received from a micro controller subsystem, receives a bit stream from the bit timing process, and handles errors depending on the state of the CAN node and CAN message fields. The implemented CAN IP is synthesized and downloaded into SmartFusion FPGA. Simulations using ModelSim and chip test results show that the implemented CAN IP conforms to the CAN 2.0A specification.

• 한국전자파학회논문지
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• 제23권12호
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• pp.1380-1387
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• 2012

송수신(T/R) 모듈은 능동 위상 배열 시스템에서 핵심 부품이다. 현재 가장 널리 적용되고 있는 모듈 구조는 Brick 형태로서 이를 소형화 하는 것은 전체 시스템 구성의 유연성을 확보할 수 있는 중요한 요소가 된다. 소형화를 위하여 MMIC 갯수를 최소화 할 수 있는 Common leg 구조를 갖는 MFC(Multi Fuction Chip) 사용이 유리하며, 이득이 높은 T/R 모듈을 고밀도로 구현하기 위하여 송수신간 격리도의 확보가 필수적이다. 본 논문에서는 Common leg 구조에서 불가피하게 발생하는 궤환 경로 문제와 이로 인한 송수신 격리도의 한계를 개선하기 위하여 바이어스 전압 제어 방법을 제안하고, 측정 결과를 기반으로 최적 바이어스 타이밍을 설계하였다. 본 논문에서 제작/측정된 TR 모듈은 일반 T/R 모듈에 비하여 약 1/2의 크기($140{\times}80{\times}16mm^3$)를 가지며, 높은 출력(채널당 7 W)과 높은 송수신 이득(35 dB 송신 이득과 30 dB 수신 이득)의 구현이 가능하였다.

• Journal of Communications and Networks
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• 제12권2호
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• pp.158-167
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• 2010

The energy efficiency of wireless infrastructure and terminals has been drawing renewed attention of late, due to their significant environmental cost. Emerging green communication paradigms such as cognitive radios, are also imposing the additional requirement of flexibility. This dual requirement of energy efficiency and flexibility poses new design challenges for implementing radio functional blocks. This paper focuses on the area vs. power trade-offs for the type of channel filters that are required in the digital frontend of a flexible, energy-efficient radio. In traditional CMOS circuits, increased area was traded for reduced dynamic power consumption. With leakage power emerging as the dominant mode of power consumption in nanoscale CMOS, these trade-offs must be revisited due to the strong correlation between area and leakage power. The current work discusses how the increased timing slacks obtained by increasing the parallelism can be exploited for overall power reduction even in nanoscale circuits. In this context the paper introduces the notion of 'area efficiency' and a metric for evaluating it. The proposed metric has also been used to compare the area efficiencies of different classes of time-shared filters.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2007년도 학술대회 1부
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• pp.197-204
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• 2007

사용자들이 직접적으로 영상의 전송과 시청 과정에 참여하고, 그 과정에서 다양한 형태로 상호작용을 할 수 있는 새로운 형태의 미디어 서비스를 인터랙티브 미디어 서비스(Interactive media service: IMS)이라고 한다. 본 연구의 목적은 이러한 인터랙티브 미디어 서비스 사용에 영향을 미치는 요인을 규명하는 것이다. 이를 위해 현재 서비스되고 있는 다양한 형태의 인터넷 미디어 서비스 사용자 12명을 대상으로 한 인터뷰를 진행하였으며 근거 이론 분석법에 따라 이를 분석하였다. 그리고 분석 결과에 따라 도출된 요인들을 바탕으로 인터랙티브 미디어 서비스 사용과 관련한 이론적 틀을 제시하고 이를 검증하기 위한 웹서베이를 실시하였다. 연구 결과, 시스템의 기술적 구조, 커뮤니케이션 맥락, 콘텐츠 특성과 같은 요인들이 인터랙티브 미디어 서비스 사용에 영향을 미치는 것으로 나타났다. 특히 실시간 인터랙티브 미디어 서비스의 경우에는 커뮤니케이션 맥락에 따른 사용 행태가 더 민감하게 나타났고, 비실시간 인터랙티브 미디어 서비스에서는 시스템의 기술적 특성과 콘텐츠 특성에 따른 사용 행태가 보다 민감한 것으로 나타났는데, 이는 인터랙티브 미디어 서비스의 시간 유연성(timing flexibility)에 따라서 사용 행태에 영향을 미치는 요인이 달라질 수 있음을 의미한다.

• 대한임베디드공학회논문지
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• 제14권6호
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• pp.339-346
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• 2019

Multi-axis servo systems are widely used in various fields such as industiral systems for improving production efficiency, robotics and complex systems where many mechanical devices and sensor systems are connected. Such a servo system requires that the servo control technique to realize the synchronization of the drive shaft in the steady state and transient conditions and to control so as to follow the target track in order to improve product precision and production efficiency. In addition, embedded type hardware is required for smooth control of the entire multi-axis system. Therefore, this paper uses hardware based on FPGA which is widely used in digital signal processing field and various control system because hardware design change is easy and parallel processing is possible. In addition, Labview based servo motor control program was studied that can control the servo motor by ensuring the performance and flexibility of the FPGA and follow the target trajectory according to various speed processing and accurate timing synchronization.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.159-166
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• 2006

The aim of synchronization of production and transportation planning in the supply chain is to increase the flexibility and to decrease various costs. The suggested model in this study synchronizes the timing to supply to a downstream manufacturer directly after production and to be consumed in a downstream manufacturer right after receipt. This model deals with the frequent delivery in small amount which is a new trend of the transportation not governed the economy of scale principle. Moreover, various types of transportation governed by the economy of scale principle or not are considered. Then, the two-phase mathematical model is suggested to obtain optimal job sequence and production quantity for each tasks. But, it is difficult to gain optimal solutions if there is a transportation governed by the economy of scale principle in the supply chain, or the size of the problem is increased. Thus, heuristic algorithms based on simulated annealing and genetic algorithm are suggested to find good solutions in the reasonable time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.313-316
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• 2001

In this paper we present the design of a JPEG Encoder using SystemC Methodology Our methodology supports the efficient mapping of C/C++ functional descriptions directly into hardware. The use of C/C++ to model al1 parts of the system provides great flexibility and enables faster simulation compared to existing methodologies. The designer can estimate system performance and verify functional correctness of the designs using commonly available software compilers. A design flow in SystemC begins with an untimed description in C++, using a library of new data types useful for modeling hardware. The description can be compiled and simulated for functional correctness. Then, the design may be refined by adding interface specification and timing information, and again the timed description can be compiled with a standard C++ compiler, simulated, and debugged.

• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.315-333
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• 2021

Due to the Global Navigation Satellite System (GNSS) modernization, recently launched GNSS satellites transmit signals at various frequency bands such as L1, L2 and L5. Considering the Korean Positioning System (KPS) signal and other GNSS augmentation signals in the future, there is a high probability of applying more complex communication techniques to the new GNSS signals. For the reason, GNSS receivers based on flexible Software Defined Radio (SDR) concept needs to be developed to evaluate various experimental communication techniques by accessing each signal processing module in detail. This paper proposes a novel SDR-based A-GNSS receiver capable of processing multi-GNSS/RNSS signals at multi-frequency bands. Due to the modular structure, the proposed receiver has high flexibility and expandability. For real-time implementation, A-GNSS server software is designed to provide immediate delivery of satellite ephemeris data on demand. Due to the sampling bandwidth limitation of RF front-ends, multiple SDRs are considered to process the multi-GNSS/RNSS multi-frequency signals simultaneously. To avoid the overflow problem of sampled RF data, an efficient memory buffer management strategy was considered. To collect and process the multi-GNSS/RNSS multi-frequency signals in real-time, the proposed SDR A-GNSS receiver utilizes multiple threads implemented on a CPU and multiple NVIDIA CUDA GPGPUs for parallel processing. To evaluate the performance of the proposed SDR A-GNSS receiver, several experiments were performed with field collected data. By the experiments, it was shown that A-GNSS requirements can be satisfied sufficiently utilizing only milliseconds samples. The continuous signal tracking performance was also confirmed with the hundreds of milliseconds data for multi-GNSS/RNSS multi-frequency signals and with the ten-seconds data for multi-GNSS/RNSS single-frequency signals.

• Wind and Structures
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• 제16권1호
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• pp.1-23
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• 2013

The wind-induced transient response of internal pressure following the creation of a sudden dominant opening during the occurrence of high external pressure, in low-rise residential and industrial buildings was numerically investigated. The values of the ill-defined parameters namely the flow contraction coefficient, loss coefficient and the effective slug length were calibrated by matching the analytical response with the computational fluid dynamics predictions. The effect of a sudden i.e., "instantaneously created" windward opening in the Texas Technical University (TTU) test building envelope was studied for two different envelope flexibility-leakage combinations namely: (1) a quasi-statically flexible and non-porous envelope and (2) a quasi-statically flexible and porous envelope. The responses forced by creating the openings at different time leads/lags with respect to the occurrence of the peak external pressure showed that for cases where the openings are created in close temporal proximity to the peak pressure, the transient overshoot values of internal pressure could be higher than the peak values of internal pressure in the pre-sequent or subsequent resonant response. In addition, the influence of time taken for opening creation on the level of overshoot was also investigated for the TTU building for the two different envelope characteristics. Non-dimensional overshoot factors are presented for a variety of cavity volume-opening area combinations for (1) buildings with rigid/quasi-statically flexible non-porous envelope, and (2) buildings with rigid/quasi-statically flexible and porous envelope (representing most low rise residential and industrial buildings). While the factors appear slightly on the high side due to conservative assumptions made in the analysis, a careful consideration regarding the implication of the timing and magnitude of such overshoots during strong gusts, in relation to the steady state internal pressure response in cyclonic regions, is warranted.

• 한국노년학
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• 제29권3호
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• pp.987-1000
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• 2009

시설입소 인지기능저하 노인은 전반적으로 활동이 부족하며 노화로 인해 근력, 유연성, 평형성 및 협응력 등이 약화되어 일상생활의 불편감 뿐 아니라 사고의 가능성이 증가되어 체계적인 활동 프로그램의 필요성이 절실하다. 본 연구는 탄력밴드를 이용한 탄력저항성운동 프로그램을 시행하여 유연성과 근력에 미치는 효과를 검증하고자 시행되었다. 본 연구는 대조군 전후 실험설계로 연구 대상자는 J시 소재의 노인시설에 거주하는 65세 이상 인지기능저하 노인 34명을 대상으로 하였다. 탄력저항성운동 프로그램 기간은 4주간으로 첫 주 3일간은 사전 조사를 수행하였으며 이후 3주간 오전에 1시간씩 일주일에 5일, 총 15일간 진행하였다. 사후 측정은 운동 프로그램이 종료 후 2일간 이루어졌다. 프로그램 시작 전·후 대상자의 일반적 특성, 일상생활동작, 인지기능, 유연성(견관절 운동범위, 상지관절 주변조직의 신장능력), 근력(악력, 어깨근력)을 측정하였다. 탄력저항성운동 프로그램 시행 후 견관절 운동범위 중 우측 굴곡, 우측 신전, 우측 외회전 범위가 실험군에서 유의하게 증가하였으며 어깨근력의 경우 좌측 굴곡 근력, 좌측 신전 근력, 좌·우측 외전 근력이 대조군에 비해 통계적으로 유의하게 증가한 것으로 나타났다. 반면에 악력과 상지관절 주변조직의 신장능력은 실험군과 대조군에서 유의한 차이가 없었다. 이상의 결과로 탄력저항성운동 프로그램은 시설 입소 노인의 유연성과 근력에 비교적 효과적인 것으로 나타났으나 프로그램의 일반화를 위해 대상자의 신체능력에 맞는 강도와 기간에 변화를 주는 연구와 효과시기, 효과의 소멸시기 등에 관한 연구가 지속되어야 하며 보다 더 정련된 프로토콜을 만들어야 함을 제언하는 바이다.