• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.5
• /
• pp.579-586
• /
• 2019

Pilot Point Method (PPM) is one of the popular methods to search hydraulic conductivities in the inverse method using groundwater flow equations. In this study, the Simultaneous Search based Pilot Point Method (SSBM) was applied with diverse information (e.g. hydraulic heads and/or tracer concentration) applications over previously developed sensitivity based Pilot Point Method (e.g. D-optimality based Pilot Point Method: DBM). In the case of DBM, due to the minimized the variance size, tracer concentration can be recognized as a tool to control the searching space of hydraulic conductivities. SSBM reduced the procedure of hydraulic conductivity searching, though it produced more variance for exploring hydraulic conductivities. In addition, SSBM was dependent on the initial hydraulic conductivity values for search finalized hydraulic conductivities. When tracer concentration was applied, searching hydraulic conductivities was more preferable than only when hydraulic head was applied. Applications of various data for searching hydraulic conductivities is recommended as a more efficient way.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.7C
• /
• pp.467-474
• /
• 2011

The performance of pilot-symbol-assisted channel estimation widely used for OFDM systems is degraded due to the small number of pilot symbols used for higher transmission efficiency. In this paper, we propose a pilot symbol based channel estimation using cross-correlation to improve the estimation performance of the OFDM system with small number of pilot symbols. The proposed technique detects a data symbol using the channel estimated by the pilot symbol and estimates the channel using the estimated data symbol and the pilot symbol. It is shown by computer simulations that the proposed technique outperforms the conventional pilot symbol assisted estimation technique.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.26 no.4
• /
• pp.129-141
• /
• 2018

In this paper, two different flight training devices were constructed to verify the effectiveness of a pilot training system based on a Virtual Reality Head Mount Display. VFR Flight Procedure and IFR Flight Procedure were conducted by high level pilots with Commercial Pilot Licence. Flight data and pilot's visual data for each flight procedure were extracted, compared and analyzed with two training systems. Finally, the effectiveness of the training systems based on the VR HMD was demonstrated by assessing the given mission and the flight results.

• Journal of Soil and Groundwater Environment
• /
• v.18 no.2
• /
• pp.45-53
• /
• 2013

Many cases of strategically designed groundwater remediation have lack of information of hydraulic conductivity or permeability, which can render remediation methods inefficient. Many studies have been carried out to minimize this shortcoming by determining detailed hydraulic information either through direct or indirect measurements. One popular method for hydraulic characterization is the pilot point method (PPM), where the hydraulic property is estimated at a small number of strategically selected points using secondary measurements such as hydraulic head or tracer concentration. This paper adopted a D-optimality based pilot point method (DBM) developed previously for hydraulic head measurements and extended it to include both hydraulic head and tracer measurements. Based on different combinations of trials, our analysis showed that DBM performs well when hydraulic head is used for pilot point selection and both hydraulic head and tracer measurements are used for determining the conductivity values.

• Journal of the Ergonomics Society of Korea
• /
• v.15 no.2
• /
• pp.99-111
• /
• 1996

In today's highly automated aircraft, the role of the pilot has changed from an airplane controller to a system manager. As a system manager in a cockpit, today's pilot is in charge of a management-level activity called cockpit task management( CTM). According to earlier studies, pilot errors in performing CTM activities were significant factors in a large number of aircraft accidents and incidents. The primary objective of this research was to reduce CTM-related pilot errors. A prototype pilot- vehicle interface called the cockpit task management system (CTMS) was developed and its effectiveness in improving CTM performance was evaluated. After the CTMS was implemented, it was integrated into a PC-based flight simulator to perform an experiment to evaluate its effectiveness. Eight volunteer subjects were used to collect performance data. The results of the experiment indicated that a statistically significant improvement was observed when the subjects flew with the assistance of the CTMS.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.25 no.1
• /
• pp.23-34
• /
• 2017

Approximately 70% of aviation accidents in the world are caused by human factors of pilots and 15-20% of these accidents are known to be caused by pilot fatigue. Recently ICAO established new standards of FRMS for aircrew. The US and the EU have introduced FRMS and established and operated new aviation regulation systems for pilot flight(duty) time limitations. On the other hand, Korea has not yet introduced FRMS. This study reviewed ICAO's standards of FRMS and analyzed the aviation regulations of the US and the EU. As a result of this study, it showed that Korea also needed to introduce FRMS. This study reasoned out plans to improve Korean aviation regulations about pilot flight time limitations based on international standards.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.11
• /
• pp.2108-2113
• /
• 2010

The Long Term Evolution (LTE) system is based on the Orthogonal Frequency Division Multiplexing (OFDM) and relies its channel estimation on the lattice-type pilot samples in the multipath fading channel environment. The estimation of the channel frequency response (CFR) makes use of the least squares estimate (LSE) for each pilot samples, followed by an interpolation both in time- and in frequency-domain to fill up the channel estimates for subcarriers corresponding to data samples. Any interpolation scheme could be adopted for this purpose. Depending on the requirements of the target system, we may choose a simple linear interpolation or a sophisticated one. For any choice of an interpolation scheme, these is a trade-off between estimation accuracy and numerical cost. For those wireless communication systems based on the OFDM and the preamble-type pilot structure, the DFT-based channel estimation and its variants have been successfully. Yet, it may not be suitable for the lattice-type pilot structure, since the pilot samples are not sufficient to provide an accurate estimate and it is known to be sensitive to the location as well as the length of the time-domain window. In this paper, we propose a simple interpolated based on the upsampling mechanism in the multirate signal processing. The proposed method provides an excellent alternative to the DFT-based methods in terms of numerical cost and accuracy. The performance of the proposed technique is verified on a multipath environment suggested on a 3GPP LTE specification.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.1125-1132
• /
• 2009

The theory and a probe of the pilot hole wall deformation method, which is a 3-dimensional stress measurement method based on the stress relief principle, were developed. A pilot hole is drilled from the bottom of a borehole and the stress measurement probe is inserted into the pilot hole. The borehole is advanced as the overcoring and the changes in the radius of the pilot hole in three directions and in the axial lengths between the borehole bottom and the pilot hole wall along four axial lines are measured by cantilever type-displacement sensors. The differences between the displacements by the elastic stress analysis and those measured by using the probe were within 3% in the uniaxial compression test of an acrylic resin plate having a hole.

• Quality Improvement in Health Care
• /
• v.27 no.2
• /
• pp.30-44
• /
• 2021

Purpose: The aim of this study was to investigate the changes in perception of the New Diagnosis-Related Group (DRG)-based payment system, make overall evaluation after participation, and examine opinions on further policy improvement among employees of a public hospital participating in the pilot project in Korea. Methods: We investigated changes in perception of the New DRG-based payment system before and after participation in the pilot project using a qualitative research method. We conducted individual in-depth interviews with the management and healthcare professionals and Focus Group Interviews (FGIs) with the staff in the nursing and administrative departments. Results: Before implementing the pilot project of the New DRG-based payment system, the management was in favor of participating in the pilot project, whereas the healthcare professionals were strongly opposed to participation in the pilot project, and the staff in the nursing and administrative departments were slightly opposed to participation. After implementing the pilot project, there were remarkable changes in the perception of the New DRG-based payment system among healthcare professionals and the administrative staff. Healthcare professionals' perception was altered in a positive way, while the administrative staff's perception of the system became negative. Conclusion: There were no restrictions on clinical practice or deterioration of quality of care observed in association with the participation in the New DRG-based payment system. However, certain unintended consequences of the New DRG-based payment system may arise as well. Therefore, the government needs to examine the problems identified in this study to reflect on and improve the New DRG-based payment system for stable expansion.

• ETRI Journal
• /
• v.31 no.5
• /
• pp.613-615
• /
• 2009

We propose a pilot-based coding (PBC) scheme for lossless bit rate reduction of parametric stereo (PS) in enhanced aacPlus. It uses PBC in addition to the existing frequency and time differential coding to encode and decode PS parameter indexes. We also design optimal Huffman codebooks (HCBs) for PBC in the proposed scheme. Experiments show that the proposed scheme is superior to the original coding scheme, where both the new coding structure and the optimal HCBs contribute to the bit rate reduction.