• Journal of Information Processing Systems
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• 제12권2호
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• pp.295-309
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• 2016

Spectrum sensing is an essential function that enables cognitive radio technology to explore spectral holes and resourcefully access them without any harmful interference to the licenses user. Spectrum sensing done by a single node is highly affected by fading and shadowing. Thus, to overcome this, cooperative spectrum sensing was introduced. Currently, the advancements in multiple antennas have given a new dimension to cognitive radio research. In this paper, we propose a multiple energy detector for cooperative spectrum sensing schemes based on the evidence theory. Also, we propose a reporting mechanism for multiple energy detectors. With our proposed system, we show that a multiple energy detector using a cooperative spectrum sensing scheme based on evidence theory increases the reliability of the system, which ultimately increases the spectrum sensing and reduces the reporting time. Also in simulation results, we show the probability of error for the proposed system. Our simulation results show that our proposed system outperforms the conventional energy detector system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.568-574
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• 2004

On-line phase tracking of an extrinsic Fabry-Perot interferometer (EFPI) and experimental vibration control of a composite beam with a sensing-patch are investigated. We propose a sensing-patch for the compensation of the interferometric non-linearity. In this paper, a sensing-patch that comprises an EFPI and a piezo ceramic(PZT) is fabricated and the characteristics of the sensing-patch are experimentally investigated. A simple and practical logic is applied for the real-time tracking of optical phase of an interferometer. Experimental results show that the proposed sensing-patch does not have the non-linear behavior of conventional EFPI and hysteresis of piezoelectric material. Moreover, it has good strain resolution and wide dynamic sensing range. Finally, the vibration control with the developed sensing-patch has been performed using Fuzzy logic controller, and the possibility of sensing-patch as a sensoriactuator is considered.

• 대한원격탐사학회지
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• 제23권5호
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• pp.439-445
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• 2007

Stereoscopic viewing is an efficient technique for not only computer vision but also remote sensing applications. Generally, stereo pair obtained at the same time is necessary for 3D viewing, but it is possible to synthesize a stereomate suitable for stereo view with a single image and disparity-map. There have been researches concerning the generation of the synthetic stereomate from remote sensing imagery. However it is hard to find researches concerning the restoration of occlusion in stereomate. In this paper, we generated synthetic stereomates from remote sensing images, focused on the occlusion restoration. In order to figure out proper restoration methods depending on the spatial resolution of remote sensing imagery, we tested several methods including general interpolation and inpainting technique, then evaluated the results.

• 한국위성정보통신학회논문지
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• 제11권3호
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• pp.119-122
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• 2016

특징 검출 기법은 원하는 신호에 대한 부분적인 정보가 수신단에 알려진 상황에서 정확도 높은 검출이 가능한 기법으로 알려져 있다. 이러한 방식의 검출 기법은 잡음이 강한 환경을 위해 제안되었다. 사이클로스테이셔너리 검출은 인지 무선 시스템에서 스펙트럼 검출 기법의 하나의 예이다. 그러나 이 기법은 원하는 신호에 대한 많은 양의 정보와 처리 시간을 요구한다. 반면, 에너지 검출 기반의 스펙트럼 검출은 단순한 기법으로 널리 알려져 있다. 그러나 에너지 검출은 잡음의 영향을 많이 받으며 이로 인한 검출 오류가 많이 발생하게 된다. 본 논문에서는 에너지와 사이클로스테이셔너리 기반의 기법을 결합하여 검출의 정확도를 높이는 한편 계산량과 처리 시간을 감소시키는 기법을 제안한다. 2단계의 문턱값을 이용하여 사이클로스테이셔너리 기법의 복잡도와 처리시간을 단축하여 시스템의 전송 효율을 증가시킨다. 시뮬레이션 결과 에너지 기반 사이클로스테이셔너리 검출 기법은 신호 검출에 소요되는 시간을 상당히 감소시키는 반면 시스템의 성능을 향상시킴을 보여준다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1002-1004
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• 2003

A ground-based, C-band full polarimetric mobile Scatterometer system has been developed in Malaysia with collaboration between Malaysian Centre for Remote Sensing (MACRES) and Multimedia University (MMU). The main purpose of this system is to measure and monitor backscattering coefficient, ${\sigma }^0$, for earth terrain such as paddy fields, forest and soil surfaces. This paper describes the preliminary results on radar backscatter measurement from paddy field using the mobile C-band Scatterometer system. The measurement campaign was conducted at Sungai Burung area in April 2003. Real time data were collected using four polarization modes (HH, HV, VV and VH), at various incidence angles ranging from 0$^0$ to 60$^0$. The measurement data show consistent results as compared to other reports, which verify the capability of this Scatterometer system as a useful tool for remote sensing.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2451-2456
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• 2003

In biological cell manipulation, manual thrust or penetration of an injection pipette into an egg is currently performed by a skilled operator, relying only on visual feedback information. Massive load of various micro injection of either genes, fluid or cells in the postgenomic era calls a more reliable and automatic micro injection system that can test hundreds of genes or cell types at a single experiment. We initiated to study cellular force sensing in zebrafish eggs as the first step for the development of a more controllable micro injection system by any inexperienced operator. Zebrafish eggs at different developmental stages were collected and an integrated biomanipulation system was employed to measure cellular force during penetrating the egg envelope, the chorion. First of all, the biomanipulation system integrated with cellular force sensing instrument is implemented to measure the penetration force of cell membranes and characterize mechanical properties of zebrafish embryo cells. Furthermore, implementation of cellular force sensing system and calibration are presented. Finally, the cellular force sensing of penetrating cell membranes at each developmental stages was experimentally performed. The results demonstrated that the biomanipulation system with force sensing capability can measure cellular force at real-time while the injection operation is undergoing. The magnitude of the measured force was in the range of several hundreds of uN. The precise real-time measurement should provide the first step forwards for the development of an automatic and reliable injection system of various materials into biological cells.

• 대한원격탐사학회지
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• 제15권3호
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• pp.167-175
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• 1999

원격탐사 관련 핵심기술은 최근에 국방, 의료영상, 환경, 지질 등과 같은 광범위한 분야에서 활용범위를 확대하고 있다. 1cm ~ 수십 cm 파장의 파를 관측하는 마이크로파 원격탐사 기술은 반사 적외선 원격탐사나 열 적외선 원격탐사 기술에 비해 날씨조건과 밤낮에 관계없이 탐사를 수행할 수 있다는 장점을 가지고 있다. 마이크로파 영상레이다인 합성 개구 레이다를 이용한 영상화 방식은 응용목적에 따라 stripmap 방식, spotlight 방식, 그리고 inverse 방식으로 구분된다. 본 논문에서는 inverse 방식으로 지상에 고정된 레이다가 비행하는 항공체를 영상화하는 기법에 대해서 기술하였다. 비행 항공체의 영상화 기법은 자동 펴적인식 시스템 구축시 중요한 기술단계이며, 최근 이 분야에 대해 활발히 연구되고 있다. 비행 항공체를 영상화하기 위해 제안된 3가지 방식인 퓨리에 처리 기법, 시간-n 주파수 처리 기법, 그리고 투시로부터 복원 기법을 소개한 후, 각 방식의 장단점을 분석하였다.

• Journal of information and communication convergence engineering
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• 제15권2호
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• pp.79-84
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• 2017

In a cognitive radio network (CRN), cognitive radio users (CUs) should be powered by a small battery for their operations. The operations of the CU often include spectrum sensing and data transmission. The spectrum sensing process may help the CU avoid a collision with the primary user (PU) and may save the energy that is wasted in transmitting data when the PU is present. However, in a time-slotted manner, the sensing process consumes energy and reduces the time for transmitting data, which degrades the achieved throughput of the CRN. Subsequently, the sensing process does not always offer an advantage in regards to throughput to the CRN. In this paper, we propose a scheme to find an optimal policy (i.e., perform spectrum sensing before transmitting data or transmit data without the sensing process) for maximizing the achieved throughput of the CRN. In the proposed scheme, the data collection period is considered as the main factor effecting on the optimal policy. Simulation results show the advantages of the optimal policy.

• IEIE Transactions on Smart Processing and Computing
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• 제5권2호
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• pp.100-106
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• 2016

Spectrum sensing is an integral part of cognitive radio, which seeks to address the perceived spectrum scarcity that is caused by inefficient utilization of the available spectrum. In this paper, a spectrum sensing system using energy detection for analog TV and FM broadcast transmitters as well as modified Integrated Services Digital Broadcasting Terrestrial (ISDB-T) signals is implemented on a software-defined radio platform using GNU' Not Unix (GNU) radio and the N200 Universal Software Radio Peripheral (USRP). Real-time implementation and experimental tests were conducted in Metro Cebu, a highly urbanized area in the southern part of the Philippines. Extensive tests and measurements were necessary to determine spectrum availability, particularly in the TV band. This is in support of the Philippine government' efforts to provide internet connectivity to rural areas. Experimental results have so far met IEEE 802.22 requirements for energy detection spectrum sensing. The designed system detected signals at -114 dBm within a sensing time of 100 ms. Furthermore, the required $P_d({\geq}90)$ and $P_{fa}({\leq}10)$ of the standard were also achieved with different thresholds for various signal sources representing primary users.

• 한국위성정보통신학회논문지
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• 제9권2호
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• pp.63-68
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• 2014

본 논문에서는 멀티콥터의 효율적 영상 전송을 위해 필요한 압축센싱 기법을 제안한다. 제안된 구조는 압축센싱에 기반한 데이터 용량을 줄이는 것에 중점을 둔다. 우선 Spectrum sensing의 기본원리를 설명하고 AMP(Approximate Message Passing)와 CoSaMP(Compressive Sampling Matched Pursuit)을 수학적 분석과 모의실험 결과를 통해서 비교한다. 또한 두 알고리즘을 계산시간과 복잡도 관점에서 평가하고 멀티콥터 동작에 적합한 알고리즘을 제안한다. 본 논문의 실험결과는 AMP 알고리즘이 CoSaMP 알고리즘보다 계산시간이 적고 이미지 에러 확률도 낮다는 것을 보여준다.