• Journal of Digital Convergence
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• v.18 no.8
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• pp.447-457
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• 2020

Mobility passengers with over four levels of autonomous driving are more likely to feel carsickness because they do not drive independently. Therefore study on how to prevent or mitigate carsickness are needed to ensure comfortable and productive moving experience of passengers. Therefore this study looked into prior researches on the causes and solutions of carsickness and conducted a survey on the specific situation of carsickness among the general public. Based on this preliminary study the four interaction guide lines for preventing and mitigating of carsickness were designed and validated by performing a CVT (Concept value test). The study have shown that people prefer auditory sense and somatic senses for response in carsickness. These current have been similar in CVT and I believe that specific interaction design proposals and validations will be needed in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.46-52
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• 2009

In this paper, the timing estimator based on the principle of the best linear unbiased estimator (BLUE) is proposed in OFDMA uplink systems. The proposed timing estimator exploits the phase information of the differential correlation between adjacent subcarriers. The differential correlation can extract the information about timing offset and mitigate the distortion of the signal caused by the frequency selectivity of channel. Compared with conventional methods, the proposed estimator shows more accurate capability in estimation. In addition, the estimator is hardly affected by the distortion caused by the frequency selectivity of channel. Simulation results confirm that the proposed estimator shows a small error mean and a relatively small error variance. In addition, the performance of the estimator is evaluated by means of SNR loss. It is shown by simulations that the SNR loss of the proposed estimator by estimation errors is less than 0.4 dB for the SNR values between 0 and 20 dB. This might indicate that the proposed estimator is suitable for the timing synchronization of multiple users in OFDMA uplink systems.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.54-63
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• 2011

This paper proposes a fast learning-based interpolation algorithm to up-scale an input low-resolution image into a high-resolution image. In conventional learning-based super-resolution, a certain relationship between low-resolution and high-resolution images is learned from various training images and a specific high frequency synthesis information is derived. And then, an arbitrary low resolution image can be super-resolved using the high frequency synthesis information. However, such super-resolution algorithms require heavy memory space to store huge synthesis information as well as significant computation due to two-dimensional matching process. In order to mitigate this problem, this paper presents one-dimensional patch-based learning and synthesis. So, we can noticeably reduce memory cost and computational complexity. Simulation results show that the proposed algorithm provides higher PSNR and SSIM of about 0.7dB and 0.01 on average, respectively than conventional bicubic interpolation algorithm.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.4
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• pp.425-435
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• 2016

This paper describes a spread-spectrum clock generation method by utilizing a ${\Delta}{\Sigma}$ digital PLL (DPLL) which is solely based on binary phase detection and does not require a linear time-to-digital converter (TDC) or other linear digital-to-time converter (DTC) circuitry. A 1-bit high-order ${\Delta}{\Sigma}$ modulator and a hybrid finite-impulse response (FIR) filter are employed to mitigate the phase-folding problem caused by the nonlinearity of the bang-bang phase detector (BBPD). The ${\Delta}{\Sigma}$ DPLL employs a two-point modulation technique to further enhance linearity at the turning point of a triangular modulation profile. We also show that the two-point modulation is useful for the BBPLL to improve the spread-spectrum performance by suppressing the frequency deviation at the input of the BBPD, thus reducing the peak phase deviation. Based on the proposed architecture, a 3.2 GHz spread-spectrum clock generator (SSCG) is implemented in 65 nm CMOS. Experimental results show that the proposed SSCG achieves peak power reductions of 18.5 dB and 11 dB with 10 kHz and 100 kHz resolution bandwidths respectively, consuming 6.34 mW from a 1 V supply.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.4
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• pp.1-8
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• 2008

In orthogonal frequency division multiplexing (OFDM) system the time selectivity of wireless channel introduces intercarrier interference (ICI), which degrades system performance in proportion to Doppler frequency. To mitigate the ICI effect, we can generally employ a classical zero-forcing (ZF) equalizer. However, the ZF scheme requires an inverse of a large matrix, which results in prohibitively high computational complexity. In this paper, we propose a low complexity ZF equalization scheme for suppressing the ICI caused by highly time-varying channels in OFDM systems. From the fact that the ICI on a subcarrier is mainly caused by several neighboring subcarriers, the proposed scheme exploits a numerical approximation for matrix inversion based on Neumann's Series (truncated second order). To further improve performance, the partial ICI cancellation technique is also used with reduced complexity. Complexity analysis and simulation results show that the proposed scheme provides the advantage of reducing computational complexity significantly, while achieving almost the same performance as that of the classical ZF a roach.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1077-1082
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• 2007

This paper presents the analysis of the potential ultra-wideband(UWB) interference to WiMAX at 3.5 GHz bands and the mitigation method using transmit power control(TPC) of UWB system. UWB interference effect is evaluated with WiMax's outage probability over UWB density when multiple UWB systems and single WiMAX receiver distribute in unit area of 1$km^2$, When UWB distribution density is 20$devices/km^2$ and the dynamic range of TPC is 30 dB, UWB interference effect with TPC is decreased by 42 % rather than that without mitigation scheme. Finally, we describe that the proposed TPC is an effective method to mitigate UWB interference to WiMAX.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.208-211
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• 2016

Device-to-Device communication(D2D) enables devices in proximity to communicate directly without going through the network infrastructure. In particular, D2D communications in a cellular network can improve the spectral efficiency by allowing the reuse of cellular resources. However, it is not easy to maintain the channel quality of the D2D links and to protect the cellular links from the D2D interferences, since the resource allocations for the cellular users will change with time due to the time-varying nature of the cellular channels. To mitigate the performance degradation of D2D links, we propose to exploit unlicensed bands as auxiliary resources when the D2D links share the uplink cellular resources. The effectiveness of the proposed scheme is verified through simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1256-1263
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• 2012

Assigning different frequency resources among adjacent cells, namely the frequency reuse technique can be utilized to mitigate intercell interference, which is a major cause of performance degradation in cellular systems. Since most of conventional frequency reuse patterns are limited to the two-dimensional environment, the research for the three-dimensional frequency reuse would be beneficial especially for the implementation of femto cells in downtown office buildings. We propose frequency reuse patterns in three-dimensional space and evaluate their performance of each pattern in terms of channel capacity. In particular, we show that the proposed three-dimensional frequency reuse patterns can be applied for carrier-aggregated transmission of LTE-Advanced systems. The performance of the proposed patterns is evaluated using computer simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.82-90
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• 2013

In this paper, conducted emission from the MDS(Motor Drive System) of a HEV/EV was analyzed using high- frequency circuit modeling in system-level approach. The conducted emission by PWM process can cause RFI(radio- frequency interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of IGBTs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the MDS. It is confirmed that the simulated result by the proposed model is well agreed with measured results in spite of a large-scaled analysis in system level. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

• Journal of Korean Academy of Nursing
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• v.31 no.4
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• pp.669-680
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• 2001

Purpose: This study is used to investigate the correlation among a stroke patient family's health, burden and quality of life. Method: Data was collected from one hundred twenty family care-givers registered at K and H Hospital in Seoul. Questionnaire data was drawn up by personal interviews aided by the staff nurses. The analyses of collected data are based on the rate of 100 percentage to the average, t-test, ANOVA, DMR, Pearson Correlation. Result: (1) The influential factors on physical health proved to be age, sex, academic career, matrimonial status, present occupation, economic situation, the relationship with the patient, the patient-caring term, and the family-formation. The psychological health issues were age, final academic career, matrimonial status, the relation with patient and the family-formation. Burdens were shown to be age, matrimonial status, the relation with patient, and the patient-caring term. The quality of life was determined by age, final academic career, matrimonial status, and the relationship with the patient, the patient- caring term, and the family-formation. (2) The rate of the physical condition was 2.87, the psychological condition 2.43, the sense of burden 3.08, and the quality of life was 2.42. (3) The rate of correlation between the burden and the quality of life was (r= -.547), the psychological health and the burden was (r= -.531), the physical health and the burden was (r= -.263), physical health and quality of life was (r= .301), psychological health, and quality of life was (r= .413). Conclusion: It follows from this study that there is a very close correlation among the stroke patient family's health, the burden, and quality of life. Therefore it is necessary that we should find various nursing intervention ways in order to mitigate the burden of family when caring for the stroke patients.