• Journal of IKEEE
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• v.2 no.1 s.2
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• pp.85-95
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• 1998

We consider two methods for the pilot signal transmission in DS/CDMA systems: Pilot channel method which is parallel to the data channel and pilot symbol method which is serial to the data channel. In this paper, we analyze the two methods. The performance of the two methods is shown to be dependent upon the added noise, fading, pilot symbol period and pilot channel power. Through the analysis, it is found that the performance of the pilot symbol method outperforms compared to the pilot channel method.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.44-50
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• 2023

For Wi-Fi and IoT wireless systems, high-capacity wireless communication technology is being applied using MIMO OFDM. Because of virtu0al subcarriers in the practical MIMO OFDM system, the pilot subcarriers cannot be spaced equally. Thus, it is difficult to obtain a good mean square error (MSE) performance of the channel estimate. This paper proposes applicable methods and the newly discovered locations of pilot subcarriers in four transmitted antennas resulting in a good MSE performance with proposed optimization algorithms.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.923-926
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• 2001

In this paper, we investigate a new approach pilot-symbol-aided channel estimation for orthogonal frequency division multi-plexing (OFDM) systems. Until now, lots of channel estimation methods are proposed. The pilot symbol assisted modulation (PSAM) has good performance. But, our proposed Algorithm has more good performance than the conventional PSAM system. Our algorithm is that channel estimation performance using the less inserted pilot-symbols systems is almost same to the two times inserted pilot-symbols system. The proposed method is highly robust to fast Rayleigh fading channel. Simulation results are presented to demonstrate the performance of our proposed algorithm.

• International Journal of Contents
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• v.14 no.2
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• pp.1-6
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• 2018

In a wireless mobile communication system, a pilot signal has been considered to be a necessary signal for estimating a changing channel between a base station and a terminal. All mobile communication systems developed so far have a specification for transmitting pilot signals. However, although the pilot signal transmission is easy to estimate the channel,(Ed: unclear wording: it is easy to use the pilot signal transmission to estimate the channel?) it should be minimized because it uses radio resources for data transmission. In this paper, we propose a pilotless channel estimation scheme (PCE) by introducing the clustering method of unsupervised learning used in our deep learning into channel estimation.(Ed: highlight- unclear) The PCE estimates the channel using only the data symbols without using the pilot signal at all. Also, to apply PCE to a real system, we evaluated the performance of PCE based on the resource block (RB), which is a resource allocation unit used in LTE. According to the results of this study, the PCE always provides a better mean square error (MSE) performance than the least square estimator using pilots, although it does not use the pilot signal at all. The MSE performance of the PCE is affected by the number of data symbols used and the frequency selectivity of the channel. In this paper, we provide simulation results considering various effects(Ed: unclear, clarify).

• Journal of Environmental Health Sciences
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• v.22 no.4
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• pp.10-15
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• 1996

Treatment of a synthetic wastewater was made for the purpose of evaluating the performance of a pilot scale of an IFBBR. The particles used in this experiment were circular shaped polystyrene whose density was lower than that of water. The reactor volume was 400 l and the SCOD removal efficiency was more than 90% at HRT of 5 hrs. The IFBBR was successfully operated for 5 months without any significant problems. And it whs certained that IFBBR had a potential capability for treating wastewater.

• Journal of Aerospace System Engineering
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• v.5 no.2
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• pp.12-17
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• 2011

Pilot and flight crew visual performance in general aviation aircraft operating is paramount for safe operation of the aircraft. Pilot compartment view, instrument and cockpit lighting forms an essential aspect of this visual performance, and therefore warrants guidance and standardization. This study introduces acceptable design criteria for pilot compartment view, instrument and cockpit illumination for general aviation aircraft.

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

• Membrane and Water Treatment
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• v.14 no.2
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• pp.85-93
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• 2023

Membrane separation is widely used for several applications such as water treatment, membrane reactors and climate change. Cross-linked organic-inorganic hybrid polyvinylidene fluoride (PVDF) / Tetraethyl orthosilicate (TEOS) was adopted for the preparation of optimized hollow membrane (HFM) for membrane distillation or other low pressure separators for mechanical properties and permeability under varying pretreatment schemes. HFMs were prepared on semi-pilot membrane fabrication system. Novel adopted post-treatment schemes involved soaking in glycerol, magnesium sulphate (MgSO₄), sodium hypochlorite (NaOCl), and isopropanol for different durations. All fibers were characterized for morphology using a scanning electron microscope (SEM), surface roughness using atomic force microscope (AFM), elemental composition by examining Energy Dispersive Spectroscopy (EDS), water contact angle (CA°) and porosity. The performance of the fibers was evaluated for pure water permeation flux (PWF). Post-treatment with MgSO₄ gave the highest both tensile modulus and flux. Assessment of properties and performance revealed comparable results with other organic-inorganic separators, HF or flat. In spite of few reported data on post treatment using MgSO₄ in presence of TEOS, this proves the potential of low cost treatment without negative impact on other membrane properties. The flux is also comparable with hypochlorite which manifests substantial precaution requirements in actual industrial use.The relatively high values of flux/bar for sample treated with TEOS, post treated with MgSO₄ and hypochlorite are 88 and 82 LMH/bar respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.9 s.252
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• pp.858-865
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• 2006

SMART Pilot is a multipurpose small capacity integral type reactor. Main coolant pump (MCP) of SMART Pilot is a canned-motor-type axial pump to circulate the primary coolant between nuclear fuel and steam generator in the primary system. The reactor is designed to operate under condition of $310^{\circ}C$ and 14.7MPa. Thus MCP has to be tested under same operating condition as reactor design condition to verify its performance and safety. In present wort a test apparatus to simulate real operating situations of the reactor has been designed and constructed to test MCP. And then functional tests, performance tests, and endurance tests have been carried out upon a prototype MCP. Canned motor characteristics, homologous head/torque curves, coast-down curves, NPSH curves and lift-time performance variations were obtained from the qualification test as well as hydraulic performance characteristics of MCP.

• 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.