• Journal of Korea Multimedia Society
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• v.14 no.2
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• pp.201-209
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• 2011

This paper suggests a panorama image stitching system which consists of an image matching algorithm: modified SURF (Speeded Up Robust Feature) and an image blending algorithm: multi-band blending. In this paper, first, Modified SURF is described and SURF is compared with SIFT (Scale Invariant Feature Transform), which also gives the reason why modified SURF is chosen instead of SIFT. Then, multi-band blending is described, Lastly, the structure of a panorama image stitching system is suggested and evaluated by experiments, which includes stitching quality test and time cost experiment. According to the experiments, the proposed system can make the stitching seam invisible and get a perfect panorama for large image data, In addition, it is faster than the sift based stitching system.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.43-47
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• 2004

A coupler or divider is a microwave passive component used for power coupling or dividing. Regarding the trend of current telecommunication systems monolithic integration of passive components is highly desirable. In this study by the LTCC(Low temperature co-fired ceramics) technology a 2012 size type dual band coupler with multi-layer structure was fabricated. To achieve the desired coupling values for both DCS and EGSM bands, broad side coupled patterns were used with multi-layer structure. Its characteristics such as coupling, insertion loss, isolation and directivity values were measured and compared with simulation results.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.445-450
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• 2007

An optimum design process of the broad-band multi-layered radar absorbing material, using genetic algorithm, is established for the radar cross section reduction of a complex target, which consists of multiple reflection structures, such as surface warships. It follows the successive process of radar cross section analysis, scattering center analysis, radar absorbing material design, and reanalysis of radar cross section after applying the radar absorbing material. It is demonstrated that it is very effective even in the optimum design of the multi-layer radar absorbing material. This results from the fact that the three factors, i.e.. the incident angle range, broad-band frequencies, and maximum thickness can be simultaneously taken into account by adopting the genetic algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.1
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• pp.350-364
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• 2022

Traditionally, in multi-user multi-carrier systems, the neighboring subband will be gapped by one subcarrier, which is set as guard band to reduce multiple access interference (MAI) between neighboring subbands. The empty subcarrier for guard band will degrade the spectral efficiency of the whole system. In order to enhance the spectral efficiency of multi-user filter bank multiple carrier (FBMC) systems, a new subband allocation method is introduced, in which the neighboring subband is gapped by half subcarrier instead of one subcarrier. Meanwhile, in order to implement the proposed resource allocation scheme, an optimized FBMC prototype filter is designed to decrease the inter-subband interference to the neighboring subband. The detailed simulations about the comparison between the proposed spectrum assignment and traditional FBMC are given, as well as the performance in the different interference scenarios. The simulation results show that the combination of the proposed spectrum assignment scheme and the optimized filter has better performance compared to the traditional scheme. The proposed scheme can be used in the system which serves massive users to get higher spectrum efficiency.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.55-59
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• 2014

Multi-band and multi-mode transmitters are needed for SDR and CR. Recently many types of polar transmitters have been studied in order to implement a multi-band and multi-mode transmitter. Polar transmitters have many advantages, such as a simple structure, high efficiency and etc. In this paper we consider the number of D/A bit and the effects of a delay mismatch as design parameters for implementing polar transmitters. From the simulation we know that a 10 bit D/A is sufficient and a delay mismatch must be maintained small than 1/64 chip for satisfying the spectrum mask characteristics. We implement a polar transmitter based on the design parameters and the measured output signal meet the spectrum mask of 800MHz CDMA.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.363-370
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• 2016

This paper proposes a Ku-band multi-mode coupler and its monopulse tracking system, which can be applied to a unmaned aircraft vehicle(UAV) platform. In general, the carrier-to-noise(C/N) level of the beacon signal from a Ku-band commercial satellite is relatively weak compared to that of a military satellite because the Ku-band satellite has been designed for commercial services. Therefore, this paper proposes a coupler and its multi-mode monopulse tracking system satisfying the tracking accuracy under a low C/N environment and analyzes the tracking accuracy. After that, we perform a real satellite tracking test and compare the accuracy of the test with the analysis result before validating the performance of the architecture of the proposed satellite tracking system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2194-2200
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• 2010

In this paper, the power detectors using metamaterials were designed and fabricated for multi-band six-port direct conversion method. The RF short-stubs for power detector were designed by using metamaterials which provide multi-band characteristics. The power detectors with metamaterial RF short-stub were analyzed and fabricated by using lumped and distributed element. The measured results of metamaterial power detectors show the good agreement with the simulation results. The performance of lumped-metamaterial RF short-stub shows the insertion loss below 1 dB and the good frequency response characteristics. Also, the distributed-metamaterial RF short-stub shows the good frequency response characteristics and the insertion loss under that of lumped-metamaterial RF short-stub. The multi-band power detectors with metamaterial RF short-stub detect the input RF signal in the designed dual frequency bands very well.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.10
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• pp.59-65
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• 2008

We have proposed a UHF/HF multi-band RFID reader, and have implemented it into a system in a package(SiP). The proposed SiP RFID reader has been designed to support both for EPCgloabal Class1 Generation2 protocol of UHF band, and 13.56MHz RFID protocols of ISO14443 A/B type, and ISO15693 standards. The operating mode is controlled by embedded RISC core, and the mode can be selected by users. The area of implemented SiP is $40mm{\times}40mm$ with 4 metal layers. The implemented reader SiP operates at single supply voltage of 3.3V. The maximum current consumption is 210mA. The operating distances are 5cm for 13.56MHz modes, and 20cm for UHF mode.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.1-8
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• 2007

In this paper, we have derived the Noise-Equation to determine the level of cross-modulation noise that is required for designing multi-band CDMA handset from IS-98 standard. From this Noise-Equation, also we were able to determine each component's specification and forecast the performance(or margin) of designing handset. In conclusion, we have designed and implemented the multi-band CDMA handset of Qualcomm's Zero-IF structure and verified validity of the Noise-Equation. In result, we have got the result of ${\pm}0.5dB$ error between Noise-Equation and actual measurement. Therefore, this paper will give a guideline for design of the Multi-Band CDMA handset.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2615-2621
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• 2010

The multi-band six-port phase correlator using metamaterial was designed and fabricated in this paper. The lumped metamaterial structure that can process the dual-band receiving signal was analyzed. Based on the analyzed results, the small-sized metamatrial six-port phase correlator for multi-band direct conversion method was proposed and fabricated. Also, the resistive power divider and $90^{\circ}$ hybrid coupler that comprises the six-port phase correlator were implemented based on the scattering parameters of metamatrial six-port phase correlator. The measured results of the proposed six-port phase correlator show the good agreement with simulation results. The performance of the six-port phase correlator shows the reflection loss below -20 dB in the dual-band. Also, the proposed six-port phase correlator got a good transmission characteristic within 1 dB gain difference and ${\pm}4.1^{\circ}$ phase imbalance, respectively.