• ETRI Journal
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• v.42 no.4
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• pp.585-595
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• 2020

Integration of multiple communication technologies in a smart grid (SG) enables employing cognitive radio (CR) technology for improving reliability and security with low latency by adaptively and effectively allocating spectral resources. The versatile features of the CR enable the smart meter to select either the unlicensed or the licensed band for transmitting data to the utility company, thus reducing communication outage. Demand response management is regarded as the control unit of the SG that balances the load by regulating the real-time price that benefits both the utility company and consumers. In this study, joint allocation of the transmission power to the smart meter and consumer's demand is formulated as a two stage multi-armed bandit game in which the players select their optimal strategies noncooperatively without having any prior information about the media. Furthermore, based on historical rewards of the player, a real-time pricing adaptation method is proposed. The latter is validated through numerical results.

• Journal of radiological science and technology
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• v.23 no.2
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• pp.69-73
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• 2000

This paper studied a C-arm's exposure condition and measured scatter rays by thickness and distance. This study reached the following conclusion. 1. Approrimately exposure dose for a patient using fluoroscopy is as follows : 2. Mostly, an operating room was not shielding by lead and operator put on only apron without thyroid and facial part protection. 3. 0.5 mmPb equivalent's apron shielded about 99% of scattered rays at 60 cm from x-ray tube. 4. Scattered rays are depended on distance and thickness so operators are should be careful when using fluoroscopy by C-arm and if possible use high frequency equipment that has a large output.

• Electronics and Telecommunications Trends
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• v.28 no.3
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• pp.106-114
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• 2013

과거 이동통신용 기지국은 기저대역 처리부와 안테나를 포함하는 RF부가 일체형으로 제작되었으나, 4세대 이동통신에서는 기술/경제적인 이유로 BBU(Base Band Unit)와 RRH(Remote Radio Head)로 분리하여 구성되는 분산형 기지국 구조를 택하는 추세이다. BBU와 RRH 간 인터페이스로 널리 사용되어온 OBSAI, CPRI외에 2010년 ORI가 출현하여 표준화가 한창이다. ORI는 시장에서 널리 사용되는 CPRI(Common Public Radio Interface)의 Vendor Specific 부분으로 인해 제조사간 호환성이 보장되기 어려운 문제를 보완하기 위하여 탄생한 인터페이스 규격으로써, CPRI를 기반으로 하면서 표준으로써의 완성도를 높인 표준이라 할 수 있다. 또한 관련 표준으로는 유일하게 IQ 데이터 압축알고리즘의 표준화를 고려하고 있다. 본고에서는 ORI의 표준화 현황과 기술적인 이슈를 소개하고, 국내의 대응 현황을 알아본다.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.257-261
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• 2008

The Digital Radio Mondiale (DRM) system is a digital broadcasting standard designed for use in the LF, MF and HF bands of the broadcasting bands below 30 MHz. The system provides both superior audio quality and improved user services / operability compared with existing AM transmissions. In this paper, we propose a variable point Prime Factor FFT design method for Digital Radio Mondiale (DRM) system. Proposed method processes a various size IFFT/FFT of Robustness Mode on DRM standard efficiently by composing Radix-Prime Factor FFT Processing Unit of form similar to Radix-4 by insertion of a variable Prime Factor Twiddle Factor and Garbage data. So, we improved limitation that cannot process 112/176/256/288 FFT of each mode of DRM system with a existent Radix Processor and increase memory size and memory access time for IFFT/FFT processing by software processing in case of implementation with a existent high speed DSP.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.395-396
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• 1996

We developed a telescope control system called ASTROS for the VST1 and VST2, which are specially designed radio telescopes to make a survey and have a 60-cm main dish. ASTROS is designed on the distributed intelligence concept and structurized programming. The hardware of the system is composed of several intelligent devices connected with de facto standard interfaces and main control unit is PC. The program is coded in the C language and its structure is object oriented in order to make easy to replace the component devices. ASTROS is now running on two twin telescopes, VST1 and VST2. VST1 is installed at Nobeyama in Japan and VST2 is installed at La Silla in Chile. They are making a galactic plane survey in CO (J=2-1) with 9 arcmin beam semi-automatically.

• Smart Structures and Systems
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• v.14 no.4
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• pp.617-641
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• 2014

The energy constraint is still a common issue for the practical application of wireless sensors, since they are usually powered by batteries which limit their lifetime. In this paper, a practical compound energy efficiency strategy is proposed and realized in the implementation of a real time wireless sensor platform. The platform is intended for wireless structural monitoring applications and consists of three parts, wireless sensing unit, base station and data acquisition and configuration software running in a computer within the Matlab environment. The high energy efficiency of the wireless sensor platform is achieved by a proposed adaptive radio transmission power control algorithm, and some straightforward methods, including adopting low power ICs and high efficient power management circuits, low duty cycle radio polling and switching off radio between two adjacent data packets' transmission. The adaptive transmission power control algorithm is based on the statistical average of the path loss estimations using a moving average filter. The algorithm is implemented in the wireless node and relies on the received signal strength feedback piggybacked in the ACK packet from the base station node to estimate the path loss. Therefore, it does not need any control packet overheads. Several experiments are carried out to investigate the link quality of radio channels, validate and evaluate the proposed adaptive transmission power control algorithm, including static and dynamic experiments.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.5
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• pp.93-102
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• 2000

This paper describes the architecture and characteristics of the satellite modem unit (SMU) developed for the DAMA-SCPC Ground System(DGS), which is a Demand Assignment Multiple Access-Single Channel per Carrier (DAMA-SCPC) satellite network. There are several requirements for the SMU from the system architecture and design concept. To meet these requirements the SMU was designed and implemented by extensively applying digital signal processing (DSP) technique and field programmable gate array (FPGA). The developed SMU met the functional and performance requirements, and has been working well. The measured BER was about 1 $\times$10E-4 in continuous mode(at Eb/No=4.7, FEC=3/4).

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.571-577
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• 2011

This paper presents a novel balanced filter design based on a metamaterial structure applicable to differential-mode excitation. The metamaterial structure is based on a unit-cell which under a differential-mode excitation behaves like composite right/left-handed(CRLH) metamaterial with filter characteristics. In contrast, the metamaterial unit-cell is below cut-off under a common-mode excitation. Experimental results are used to verify the proposed metamaterial's differential-mode characteristics. The metamaterial is fabricated with a balanced filter design resulting in an operating frequency range of 960~1000 MHz with a insertion loss of 4.1 dB.

• Journal of Biosystems Engineering
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• v.27 no.5
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• pp.459-466
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• 2002

In Korea, a need of automatic dairy farm management system has been increased to lower production cost and to strengthen international competition. However, the present management system was mostly relied on foreign technologies and caused some problems in post management and after-sales services. Therefore, though there is a problem of price and quality at present, domestic technologies of the management system should be developed for the long run. This study was conducted to develop an electronic identification unit for an automatic dairy farm management system. The developed system was consisted of a tag, a reader, a switching circuit, and a personal computer. The tag attachable to each individual cow was developed to transmit individual radio frequency(RF) code into the air with modulation of ASK(amplitude shift keying). And the switching circuit was added to avoid confusion on reception and transmittance. The reader attached to a feeding device was developed to transmit activating signal periodically and to identify code of the individual tag when the tag was approached to the device. The reader was consisted of an active filter, a detecter, a comparator and a microcontroller. The test result was feasible enough to apply it for the automatic farm management system and the identified maximum distance was about 37cm.

• 전자공학회논문지 IE
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• v.48 no.3
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• pp.20-25
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• 2011

We developed a method of accelerating the operation speed of communication systems for SDR(Software Defined Radio) systems in WiBro environment. In this paper, we propose a new scheme of using GPU(Graphics Processing Unit) for implementing the communication system which perform with the functionality of SDR. In general, communication systems is made by DSP(Digital Signalling Processor) or FPGA(Field Programmable Gate Array). However, in this case, there are exist the problem of implementation and debugging caused by each CPU characteristic. The GPU is optimized for vector processing because it usually consists of multiple processors and each processor in GPU is composed of a set of threads. We also developed Framework to use GPU and CPU resources effectively for reducing the operation time. From the various simulation, it is confirmed that GPU system have good performance in WiBro system.