• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.11
• /
• pp.26-32
• /
• 2014

Single-Carrier Frequency division multiplexing (SC-FDM) has been selected for the uplink transmission technique in 3GPP-LTE since it has an advantage of low peak-to-average power ratio (PAPR) in user's perspective. The receiver typically uses a frequency domain equalizer, which, however, suffers from noise boost and/or residual ISI especially when the channel has deep nulls. In this paper, we propose using turbo equalizer to mitigate such a problem. We provide link level performance comparison and an insight into how many iteration is needed for reasonable performance and complexity.

• Journal of the Semiconductor & Display Technology
• /
• v.15 no.2
• /
• pp.1-5
• /
• 2016

3D printer is the equipment of the system for sequentially layer laminated in the materials. Now 3D printer used in various fields such as, semiconductor, electricity automobile, medical and various types of output method and material. In this paper, we studied about the improvement on warpage due to shrinkage of product from 3D printer of FDM(Fused Deposition Modeling) type, we proposed measures systematically to solve warpage problem using of 6SC(6 Step Creativity) method of practical TRIZ. After experimented with product prototypes experiment, we verified effect about solution.

• Journal of the Semiconductor & Display Technology
• /
• v.17 no.4
• /
• pp.70-75
• /
• 2018

In this paper, we have studied the deformation problem of the scaffold caused by the FDM type 3D printer. The DOE (Design of experiment) and 3SC was used to solve the deformation problem of the scaffold generated from the adhesion surface between the scaffold and the bed. The methodology was used to derive the solution and the experiment was conducted on the derived solution. As a result of evaluating the experimental results obtained for the solution, it was found that the deformation of the scaffold was much improved. By using the DOE, We were possible to derive the output condition of scaffold.

• The Journal of the Acoustical Society of Korea
• /
• v.35 no.1
• /
• pp.1-7
• /
• 2016

This paper proposes an adequate UWA (Underwater Acoustic) communication system of underwater communication network in the Yellow Sea. UWA channel is obtained from Bellhop ray tracing method with Yellow Sea environments. Based on this channel, communication parameters for CDMA (Code Division Multiple Access) and SC-FDM (Single Carrier-Frequency Division Multiplexing) using diversity techniques are calculated. In order to prove the proposed methods, BER (Bit Error Rate) and data rate are obtained using computer simulations and the adequate communication system for long rms delay spread and low Eb/No environments is proposed from the simulation.

• Journal of the Semiconductor & Display Technology
• /
• v.18 no.3
• /
• pp.25-30
• /
• 2019

In this paper, we have analyzed manufacturing problems of the scaffold with pores using FDM 3D printer and PLGA. We suggested the solutions using 3SC practical TRIZ. We selected the final solution used machine learning. We reduced number of experiments using most influential factor after analysis print factors. We printed the scaffold and measured pore size. We created the regression model using python tensorflow. The print condition data of measured pore size was used as training data. We predicted the pore size of printed condition using regression model. We printed the scaffold using the predicted the print condition data. We quantitatively compare the predicted scaffold pore size data and the measured scaffold pore size data. We got satisfactory result.

• Journal of Communications and Networks
• /
• v.9 no.1
• /
• pp.34-42
• /
• 2007

Orthogonal frequency division multiplexing (OFDM) combined with time division multiplexing (TDM), in this paper called OFDM/TDM, can overcome the high peak-to-average-power ratio (PAPR) problem of the conventional OFDM and improve the robustness against long time delays. In this paper, the bit error rate (BER) performance of OFDM/FDM in a frequency-selective Rayleigh fading. channel is evaluated by computer simulation. It is shown that the use of frequency-domain equalization based on minimum mean square error criterion (MMSE-FDE) can significantly improve the BER performance, compared to the conventional OFDM, by exploiting the channel frequency-selectivity while reducing the PAPR or improving the robustness against long time delays. It is also shown that the performance of OFDM/FDM designed to reduce the PAPR can bridge the conventional OFDM and single-carrier (SC) transmission by changing the design parameter.

• Journal of the Semiconductor & Display Technology
• /
• v.16 no.4
• /
• pp.25-29
• /
• 2017

In this paper, we have studied the deformation problem of the scaffold caused by the FDM type 3D printer. The Practical TRIZ technique was used to solve the deformation problem of the scaffold generated from the adhesion surface between the scaffold and the bed. The Practical TRIZ methodology was used to derive the solution and the experiment was conducted on the derived solution. As a result of evaluating the experimental results obtained for the solution, it was found that the deformation of the scaffold was much improved to the satisfactory level.