• Tunnel and Underground Space
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• v.13 no.5
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• pp.353-361
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• 2003

For RMR and Q rock mass classification at the design and construction stage, evaluation of groundwater condition is usually based upon the experience due to the restriction of available methods. Based on the results of Taejon LNG Pilot Cavern which acquire joint water pressure, inflow rate of ground water and hydraulic conductivity model, estimates from numerical analysis and analytical solutions were compared to verify each evaluation method. As the result, the Raymer(2001) approach was found to be efficient for estimating inflow rate and corresponding value.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.97-105
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• 2015

A navigation signal based on orthogonal tiered polyphase code was proposed. For the proposed signal, tiered polyphase code was used as the code of a pilot channel. Tiered polyphase code is a complex number type code, and thus the pilot channel and data channel were separated using the Walsh code which makes the correlation between different codes become 0. The results of the simulation indicated that the correlation characteristics and signal acquisition performance of the proposed signal were identical to those of tiered polyphase code, and that the disadvantage of tiered polyphase code could be supplemented through a data channel in terms of signal tracking.

• Korean Journal of Oriental Medicine
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• v.14 no.3
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• pp.73-79
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• 2008

This pilot study aimed to set up a reasonable method for measuring body segments parameters and finding out some useful body segments parameters to diagnose Sasang constitutions. In this study, we have tried to take a secure effort in measuring and diagnosing of Sasang constitutions based on the consensus among Sasang constitution experts. And we also have tried to find out some useful body segments parameters based on the actual data. We measured 9 clinically meaningful body lengths specified by Sasang constitution experts and analyzed these parameters statistically according to each Sasang constitution. We have found that Taeeumin female's ratio of foot length to height was significantly large and Soyangin's ratio was significantly small, but more data are needed to confirm this finding.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2610-2612
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• 2004

The polyphase filter-based orthogonal frequency division multiplexing (PF-OFDM) is proposed in [1]. It provides more efficient data transmission mechanism than the classical OFDM method. However, the channel estimation mechanism in the classical OFDM system such as the cyclic prefix can not be applied straightforwardly, since the received signal contains unpredictable terms. Therefore, the PF-OFDM system requires a complicated channel estimation scheme when it works on the multipath fading communication channel. In this paper, we proposed a pilot-symbol aided channel estimation algorithm suitable for the PF-OFDM system which efficiently deals with the unpredictable terms and verified its performance through a series of computer simulations.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.358-360
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• 2008

Recently there are many pilot studies for advanced application of first Korea national high resolution satellite image, which is called as KOMPSAT-MSC (Korean Multi-purpose Satellite-Multi-Spectral Camera), in Korea. In this study the forest type classification methodology is developed and its distribution map was constructed by applying high resolution satellite image, KOMPSAT-MSC, based on Tasseled Cap Transformation, especially through comparing the result of detailed filed surveying such as forest type, tree species, tree diameter, tree age and tree crown density in pilot study area.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.8
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• pp.400-405
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• 2001

Quadrature Amplitude Modulation(QAM) is well known a bandwidth efficient modulation scheme. However, its use for mobile communications has been limited due to noise and signal distortion. Recently, the QAM scheme is emerging as a new modulation scheme for a band-limited wireless system. In this paper, we propose an iterative decoding algorithm assuming QAM signal for a narrow-band mobile channel. The Algorithm is based on the EM(Expectation Maximization) Algorithm, and the performances of the proposed decoder are assessed using computer simulation. The simulation results show that the proposed decoder perform better compared to that of other schemes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.384-389
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• 2004

In this paper, we investigate channel estimation techniques based on the comb-type pilot arrangement for a mobile MIMO OFDM system. Moreover, to enhance channel estimation, an efficient channel estimation technique is proposed. Simulation results show that the proposed channel estimator is accurate and effective for tracking variations of channels between multiple transmit antennas and receive antennas in time-varying radio channels.

• Journal of Information Processing Systems
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• v.17 no.6
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• pp.1083-1096
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• 2021

Compressed sensing-based matching pursuit algorithms can estimate the sparse channel of massive multiple input multiple-output systems with short pilot sequences. Although they have the advantages of low computational complexity and low pilot overhead, their accuracy remains insufficient. Simply multiplying the weight value and the estimated channel obtained in different iterations can only improve the accuracy of channel estimation under conditions of low signal-to-noise ratio (SNR), whereas it degrades accuracy under conditions of high SNR. To address this issue, an improved weighted matching pursuit algorithm is proposed, which obtains a suitable weight value u_op by training the channel data. The step of the weight value increasing with successive iterations is calculated according to the sparsity of the channel and u_op. Adjusting the weight value adaptively over the iterations can further improve the accuracy of estimation. The results of simulations conducted to evaluate the proposed algorithm show that it exhibits improved performance in terms of accuracy compared to previous methods under conditions of both high and low SNR.

• Journal of Navigation and Port Research
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• v.36 no.7
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• pp.571-575
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• 2012

Berthing and unberthing maneuver is essential work for marine pilots and securing the safety against risks during the maneuver is more important than anything else. Moreover, the maneuvering environment in ports and harbors has changed rapidly and got worse due to development of a new port, the advent of a new type or large-sized ship, and the rapid increase in harbor traffic. As one of measures taken to cope with such changes in the maneuvering environment and for each pilot to improve his own maneuvering ability, this paper developed laptop-based ship-handling simulator which is readily available anytime and anywhere. This paper is to develop a conning display for ship's maneuvering and electronic chart based display widely used nowadays to represent a model ship's movement. The displays were arranged appropriately considering pilot age, easy handling by mouse, using a maximum screen, proper arrangement of rudder, engine, thruster, tug etc and representation of information. Up to now thirteen (13) model ships were developed based on real-ship, whose mathematical model is Japanese MMG & pilots' low speed maneuver.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.23-35
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• 2023

Evidence-based training (EBT) improves a pilot's competency and confidence based on the data(Evidence) from actual aircraft accidents, incidents, operations, and training for safe operation in the fast-paced and large-scale air transportation field. It is a training/assessment program that strengthens resilience for problem solving. As a way to apply this evidence-based training(EBT) to the educational system of ATO and to resolve the problems, I propose 3 improvement plans. They are evaluation criteria that apply the core competencies of EBT to the educational evaluation system, the way to improve the system for standardization of practical test examiners and instructors and also the ways to use Flight Simulation Training Devices(FSTD).