• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.462-468
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• 2010

A new course keeping controller for RIB(Rigid Inflatable Boat)-type USV(Unmanned Surface Vehicle) is developed using pilot's steering pattern. A pilot's simple steering pattern is found out from various course change tests. It is used to course keeping algorithm, suitable for large course change more than 60 degrees. To validate the course keeping controller, sea trial tests are conducted. From sea trial test, new course keeping controller shows good performance with less overshoot, maximum roll angle less than $20^{\circ}$, which makes it possible that fast course changes without slip motion of USV.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.69-75
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• 2000

A new frame synchronization confirmation technique using a pilot pattern of both uplink and downlink channels is proposed for W-CDMA (Wideband Code Division Multiple Access) system. It is shown that by using this technique, we can cancel the side lobe for autocorrelation functions of the frame synchronization words of pilot pattern have the maximum to-of-phase autocorrelation value "4" with two peak values equal in magnitude and opposite in polarity at zero and middle shifts. Due to this side lobe cancellation effect, therefore, the autocorrelation function of the frame synchronization words becomes ideal for the frame synchronization confirmation since double maximum correlation values equal in magnitude and opposite polarity at zero ad middle shifts can be achieved. This property can be used to double check frame synchronization timing and thus. improve the frame synchronization confirmation performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.3055-3070
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• 2013

This paper proposes an improved carrier frequency offset (CFO) and sampling frequency offset (SFO) estimation scheme for orthogonal frequency division multiplexing (OFDM) based broadcasting system with cyclic delay diversity (CDD) antenna. By exploiting a periodic nature of channel transfer function, cyclic delay and pilot pattern with a maximum channel power are carefully chosen, which helps to enable a robust estimation of CFO and SFO against the frequency selectivity of the channel. As a performance measure, a closed-form expression for the achievable mean square error of the proposed scheme is derived and is verified through simulations using the parameters of the digital radio mondiale standard. The comparison results show that the proposed frequency estimator is shown to benefit from properly selected delay parameter and pilot pattern, with a performance better than the existing estimator.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.14 no.1
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• pp.70-78
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• 2010

Objectives : To qualify or enhance the diagnostic ability of students in Oriental Medicine, so called standardized patients are ideal modality, but because it's a man-based method, more convenient tools are required. Computer-based diagnostic ability test program gives effective way for the very purpose. So we made a pilot software evaluating Pattern Identification ability in Oriental Medicine. Methods and Materials : The pilot software was coded with Microsoft's EXCEL VBA. 87 names of Zheng (Symptom Pattern) and 674 names of symptom (including some signs) are adopted from the former standardization works conducted by Korean Institute of Oriental Medicine (KIOM) in 1996. Results : Compared with some manned modalities to test Pattern Identification ability, the test by this software shows superiority in convenience and objectivity. Conclusion : This software is world's first program to perform computer-based evaluation of Pattern Identification in Oriental Medicine, and it gives effective way to complement both written test and manned clinical performance test (CPX).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.333-342
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• 2014

The pilot assisted channel frequency response (CFR) estimation schemes for an OFDM-based system with virtual subcarriers are analyzed under the assumption that pilot symbols are located according to a comb-type pattern in the OFDM block. In particular, as the minimum mean square error (MMSE) based scheme aiming to directly predict the channel impulse response and the MMSE based scheme aiming to suppress the leakage have not been clearly compared, by proving that the mean square errors (MSEs) of the latter scheme is always larger than that of the former scheme, this paper shows that the former scheme is superior to the latter scheme. Moreover, the impact of the number of pilots on the performances of the MMSE and least-square based channel estimation schemes are investigated. The performance analyses of the presented schemes are confirmed by computer simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.273-279
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• 2007

I evaluate the BER performance of OFDM systems in frequency selective Doppler time variant fading channels, considering the pilot patterns for channel estimation. The performance of the systems is degraded due to channel estimation error. For the reduction of performance degradation in acceptable level, the optimum distance of pilot symbols in pilot pattern is 5 subcarriers in frequency domain and 6 OFDM block in time domain.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.49-49
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• 2018

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.86-94
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• 2009

Currently, positioning methods for LBS(Location Based Service) are GPS and network-based positioning techniques that use mobile communication networks. In these methods, however, the accuracy of positioning decreases due to the propagation delay caused by the non-line-of-sight(NLOS) effect and the repeater. To address this disadvantage, the CDMA system uses Pattern Matching algorithm. The Pattern Matching algorithm constructs a database of the propagation characteristics of the RF signals measured during the GPS positioning along with the positioned locations, so that the location can be provided by comparing the propagation characteristics of the received signals and the database, upon a user's request. In the area where GPS signals are not received, however, a database cannot be constructed. There are problem that the accuracy of positioning decreases due to the area without a database Because Pattern Matching algorithm depend on database existence. Therefore, this paper proposed a pilot signal strength prediction algorithm to enable construction of databases for areas without databases, so as to improve the performance of the Pattern Matching algorithm. The database was constructed by predicting the pilot signals in the area without a database using the proposed algorithm, and the Pattern Matching algorithm analysed positioning performance.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1082-1085
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• 2002

By improving Ec/Io of pilot channel in CDMA mobile communication, the transmitting quality of mobile phone may be improved, channel capacity may be increased, and further investment and operation cost may be reduced to build a network. In this paper suggested new cell pattern decision method for base station as one of ways to improve Ec/Io of pilot channel and verified its utility through simulation and field application data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.664-670
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• 2005

OFDM is a very attractive technique for achieving high-bit-rate data transmission and high spectrum efficiency in fading environment. However, the reliable detection of an OFDM signal in time-varying multipath fading channels is a challenging problem. Accordingly, various channel estimation methods have been proposed for performance improvement. But, conventional pilot patterns for channel estimation in OFDM systems have not robust characteristics relating to various mobile speed. To solve this drawback in conventional patterns, we propose the pilot patterns modified from conventional patterns to have a good error performance in time-varying fading channel. Simulation results show that the performance of the proposed pilot patterns is better than conventional patterns in fast time-varying channel.