• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.179-185
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• 2020

DRAM is a major component of the main memory system. As the operating system evolves and application complexity and capacity increases, the capacity and speed of DRAM are also increasing. DRAM should perform a refresh action of periodically reading and then re-storing stored values, and the accompanying performance and power/energy overhead embodies characteristics that worsen as capacity increases. This study proposes an energy efficiency improvement technique that efficiently stores the rows that need to be refreshed within 64ms and 128ms using the bloom filter for cells with the lowest retention time of electrons. The results of the experiment showed that the proposed technique resulted in an average 5.5% performance improvement, 76.4% reduction in average refresh energy, and 10.3% reduction in average EDP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.959-966
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• 2010

Quantitative ultrasound analysis provides fundamental information of various ultrasound parameters using spectral information of the short-gated radiofrequency(RF) data. Therefore, accurate extraction of spectral information from backscattered RF signal is crucial for further analysis of medical ultrasound parameters. In this paper, we propose two techniques for calculating a more accurate power spectrum which are based on the phase-compensation using the normalized cross-correlation to minimize estimation errors due to phase variations, and the weighted averaging technique to maximize the signal-to-noise ratio(SNR). The simulation results demonstrate that the proposed method estimates better results with 10% smaller estimation variances compared to the conventional methods.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.174-180
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• 2014

In this paper, we propose the random pixel sampling technique to solve the high computational complexity in the perceptual SSIM-based backlight dimming. Specifically, the proposed algorithm selects pixels in a total frame considering the pre-defined number, and generates the block by combining these pixels. Then, it estimates parameters, which are required in the SSIM calculation, in the combined block, and hence, it can reduce the computation time significantly. In the experimental results, the proposed algorithm reduced the average power consumption and computation time by up to 38.1776 % and 99.5828 %, respectively while preserving the average SSIM., compared with the conventional algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.415-415
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• 2019

본 연구에서는 낙동강 본류에서 10년(2008~2017) 동안 관측된 자료의 월별 평균 자료를 이용하여, DO, BOD, COD의 시공간 변동 및 그 영향인자들과의 상관관계를 분석하였다. 관측소별 수질은 상류에서 하류로 갈수록 나빠졌으며, BOD와 COD는 ST5에서 가장 높았다. 10개 관측소별 수질성분의 상관성을 분석한 결과, DO와 수온의 상관계수는 -0.90 이상이고, BOD와 Chl-a의 상관계수는 0.48~0.85, COD와 TOC의 상관계수는 ST5와 ST10 관측소를 제외하고 0.65 이상이었다. 모든 관측소 자료를 이용한 회귀분석 결과, 수온과 DO는 감소하는 선형함수로서 결정계수는 0.90, chl-a와 BOD는 증가하는 파워함수로서 결정계수는 0.83, TOC와 COD는 증가하는 로그함수로서 결정계수는 0.58 정도이었다. 10개 관측소별 TOC 분해율을 산정한 결과, BOD에 의한 분해율의 평균은 15.5~36.3%, COD에 의한 분해율의 평균은 57.4~89.6%의 범위로 나타났다.

• 한국노년학
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• v.30 no.3
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• pp.793-802
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• 2010

The purpose of this study was to examine the influence of extreme heat on muscle function and muscle injury marker in elderly women. The subjects of this study were eight post-menopausal elderly women without any metabolic disease. All eight subjects were asked to perform the knee joint isokinetic exercise using isokinetic equipment (cybex) in the laboratory and experimental temperature within laboratory was adjusted to two conditions: extreme heat temperature(33±0.5℃) and normal temperature(20±0.5℃) maintained in 50±3% humidity conditions. Each experimental exercise was monitored and analyzed the change of HSP70, LDH and CK. Muscular functions (peak torque, total work, percentage of peak torque body weight, fatigue index, average power and total work) were significant differences at exercise between temperatural conditions (p<.05). In extreme heat temperature, muscular injury markers (HSP70, LDH and CK) were increased, threfore resulted in significantly higher than normal temperature(p<.05). These results show that extreme heat temperature can decrease muscle function in elderly women.

• Geophysics and Geophysical Exploration
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• v.19 no.2
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• pp.67-75
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• 2016

To investigate spatial and temporal variations of low-frequency (${\leq}5Hz$) ambient seismic noise, we analyzed the noise data recorded for one whole year of 2014 at surface accelerometer stations in South Korea. After decomposed into low-frequency (LF; < 1 Hz) and high-frequency (HF; ${\geq}1Hz$) components, the root-mean-squared (RMS) amplitudes and power spectral densities (PSD) of the noise data were computed. The RMS amplitudes were larger on islands and near-shore stations, but also large RMS amplitudes were observed at inland stations in large cities only for HF components. The RMS amplitudes of HF components were larger in the daytime than at nighttime and during weekdays than on Sunday and holidays. This indicates the HF components are closely related to human activities. On the contrary, daily and weekly variations were not clear in the LF components while they showed seasonal variations with its maximum during the winter and a good correlation with significant wave height. Therefore, we interpret the mechanism of LF components is closely related to natural phenomena such as sea. The amplitude of LF components decreased as an exponential function of the distance to the center of typhoons. The exponential index of -0.76 suggested that ambient seismic noise included both surface and body waves. Peak frequencies of the PSD curves were near 0.34 Hz indicating the double frequency. No temporal variation in the peak frequency was clearly noticed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.103-108
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• 2016

In daily life, humans get stress very often. Stress is one of the important factors of healthy life and closely related to the quality of life. Too much stress is known to cause hormone imbalance of our body, and it is observed by the brain and bio signals. Based on this, the relationship between brain signal and stress is explored, and brain signal based stress index is proposed in our work. In this study, an EEG measurement device with 32 channels is adopted. However, only two channels (FP1, FP2) are used to this study considering the applicability of the proposed method in real enveironment, and to compare it with the commercial 2 channel EEG device. Frequency domain features are power of each frequency bands, subtraction, addition, or division by each frequency bands. Features in time domain are hurst exponent, correlation dimension, lyapunov exponent, etc. Total 6 subjects are participated in this experiment with English sentence reading task given. Among several candidate features, ${\frac{{\theta}\;power}{mid\;{\beta}\;power}}$ shows the best test performance (70.8%). For future work, we will confirm the results is consistent in low price EEG device.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.61-67
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• 2019

The purpose of this study is to apply self-leadership program using films to nursing students and to confirm the effects of self-leadership, empowerment, self-directed learning and happiness. The study participants were 60 nursing students, the data was collected from March 7, to June 13, 2017. The data was analyzed by frequency, percentage, mean, standard deviation, and paired t-test using SPSS WIN 24.0 computer program. The self-leadership program consisted of 13 sessions, and 14 films were used for self-management, self-training, and self-branding. The self-leadership of nursing students was significantly increased after education(t=-4.38, p<.001). In details, behavior-focused strategies, natural-reward strategies, and constructive thought pattern strategies were all significant. Empowerment also increased significantly after education(t=-5.83, p<.001), and personal skills, collective recognition, and self-determination were all significant. Self-directed learning were high after education(t=-3.31, p=.002), and learning plans and learning practices were significant. In addition, the happiness of nursing college students was significantly higher after education(t=-4.49, p<.001). As a result of this study, self-leadership program using movies can improve self-leadership, empowerment, self-directed learning and happiness of nursing students and It will be possible to apply as educational intervention in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.229-238
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• 2013

The aim of this study is to evaluate university canadian paddlers' iso-kinetic muscle function and provide training advices. Eight university paddlers with a 8.5 years career participated in this study. Inbody 720, biodex system III, biodex stabilizer system and THP 2 are used to investigate body component, muscle function(peak torque, average power and work fatigue), agility and dynamic balance. Iso-kinetic muscle function around shoulder, thorax and knee are measured. And then bilateral and unilateral muscle imbalance are calculated at each joint. Results of this study are as follows; University canadian paddlers' BMI average is 24.90 $kg/m^2$ and percent body fat is 12.23%. Reaction time average was 324 msec and balance score at each leg are below 2.0. A3, A4, A5, A6, A8 are needed to train shoulder muscle strength and power. A1, A2, A7, A8 are needed to strengthen shoulder muscle endurance. A2, A5, A8 are needed to train thorax muscle strength and power. A1, A8 are needed to strengthen thorax muscle endurance. Most of paddlers' reciprocal muscle balance ratio on thorax and knee are out of normal range. A2, A3, A4, A8 are needed to train abdominal strength and A3, A5, A6, A7, A8 are needed to train hamstring strength.

• The Journal of the Acoustical Society of Korea
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• v.27 no.5
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• pp.256-261
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• 2008

In this paper, we propose a novel approach to improve the performance of minima controlled recursive averaging (MCRA) which is based on the conditional maximum a posteriori criterion. A crucial component of a practical speech enhancement system is the estimation of the noise power spectrum. One state-of-the-art approach is the minima controlled recursive averaging (MCRA) technique. The noise estimate in the MCRA technique is obtained by averaging past spectral power values based on a smoothing parameter that is adjusted by the signal presence probability in frequency subbands. We improve the MCRA using the speech presence probability which is the a posteriori probability conditioned on both the current observation the speech presence or absence of the previous frame. With the performance criteria of the ITU-T P.862 perceptual evaluation of speech quality (PESQ) and subjective evaluation of speech quality, we show that the proposed algorithm yields better results compared to the conventional MCRA-based scheme.