• Communications for Statistical Applications and Methods
• /
• v.22 no.3
• /
• pp.295-304
• /
• 2015

This paper considers the problem of estimation of the Hurst parameter H ${\in}$ (1/2, 1) from longitudinal data with the error term of a fractional Brownian motion with Hurst parameter H that gives the amount of the long memory of its increment. We provide a new estimator of Hurst parameter H using a two scale sampling method based on $A{\ddot{i}}t$-Sahalia and Jacod (2009). Asymptotic behaviors (consistent and central limit theorem) of the proposed estimator will be investigated. For the proof of a central limit theorem, we use recent results on necessary and sufficient conditions for multi-dimensional vectors of multiple stochastic integrals to converges in distribution to multivariate normal distribution studied by Nourdin et al. (2010), Nualart and Ortiz-Latorre (2008), and Peccati and Tudor (2005).

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.21 no.6
• /
• pp.1543-1548
• /
• 2007

Recent experiments investigating the analgesic or anti-stress effects of electro-acupuncture provide extensive evidence that opioid or stress hormone system is involved in those effects, respectively. It has been also suggested that opioid or stress hormones modulate long-term memory consolidation or retrieval in animals and human subjects. This article reviews the possibilitythat electroacupuncture can modulate memory consolidation or retrieval. The release of serum cortisol is enhanced or reduced by high-frequency or low-frequency electroacupuncture, respectively. Also the release of beta endorphin and enkephalin is enhanced by low-frequency electroacupuncture and the release of dynorphin is enhanced by high-frequency electroacupunture. The memory consolidation is enhanced by post-training injection of Glucocorticoids, Naloxone or Dynorphin. So this review suggests strongly that memory consolidation can be modulated by electroacupuncture.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.12
• /
• pp.665-672
• /
• 2000

This paper described the measurement technology to analyze the partial discharge characteristics for long term aging of insulations. This system was consisted of high voltage generation and measurement part, PD detection part, digital conversion and signal processing part. We used the VXI system for digital conversion and signal processing part. In the digital conversion part, we studied the error of partial discharge magnitude and memory capacity for reading digital signal with the sampling rate. In the signal processing part, we showed the program algorithm to count pulses and read peak values of partial discharge. The allowable minimum sampling rate of digizer was decided to 250kS/s through analyzing test. We confirmed that this system was very useful in the study of $\phi-q-n$ characteristics of long term PD experiments with specimens being consisted of internal void defects and CIGRE II electrodes.

• The Korean Journal of Archival Studies
• /
• no.10
• /
• pp.27-62
• /
• 2004

As the penetration of information technology into everyday life is accelerated day by day, virtually all kinds of human representation of knowledge and arts are produced and distributed in the digital form. It is problematic, however, because digital objects are so volatile that it is not easy to keep them in fixed form. The fatal fragility makes it extremely tricky to preserve the digital heritage of our time for the next generation. The present paper aims to introduce current endeavors made at the international and the national levels and to provide with suggestions for Korean national strategy of digital preservation. It starts with reviewing the global trends of digital archiving and long-term preservation, focusing on standardization, preservation strategies and current experiments and projects being conducted for preserving various digital objects. It then sketches national strategies of several leading countries. Based on the sketch, twofold suggestions for Korean national strategy are proposed: establishing a central coordinating agency and accommodating the digital preservation issue in the legislative and regulatory framework for the information society. The paper concludes with the necessity of cooperation among heritage organizations, including libraries, archives, museums. They should cooperate with each other because they have traditionally been trusted with the custodianship of collective memory of humankind and the digital heritage cannot be passed onto the next generation without their endeavor. They should also work together because any single institution, or any single nation could cover what it takes to complete the task of long-term preservation of our digital heritage.

• Anxiety and mood
• /
• v.6 no.2
• /
• pp.102-108
• /
• 2010

Objective : Although studies have explored responses to fear had been assessed using various psychophysiological methods, results have been inconsistent. The present study examined psychophysiological responses in healthy subjects after viewing fear stimuli in a video clip for set up future fear related psychophysiological studies. Methods : We monitored three psychophysiological variables (electroencephalography, skin temperature, and heart rate variability) in adults who watched either a control stimulus movie clip or a fear-inducing movie clip. Results : In 16 healthy adults, theta activity decreased significantly after the fear stimulus as compared to the normal stimulus. However the participants showed no differences in heart rate variability or skin temperature between the fear and normal control stimulus situations. Conclusion : In the limbic area, theta activity corresponds with information processing, integration into previous memories and long-term potentiation. In this study, we suggest decreased theta activity represents amygdalo-hippocampal activity, associated with fear, short-term memory, and memory extinction in the healthy adults. Further studies are needed to evaluate the interaction of fear, memory, and the pathophysiology of anxiety disorder in patient with anxiety disorders.

• Sleep Medicine and Psychophysiology
• /
• v.3 no.1
• /
• pp.15-24
• /
• 1996

After rapid eye movement(REM) sleep was idenified in 1953, a lively interest developed concerning a possible role of this kind of sleep in memory processes. The author reviewed studies relating REM to memory/learning. Many studies in animals and humans gave substantial evidence for relating REM sleep to memory function. The evidence supporting the position taken in this paper comes from experiments showing that : (1) learning session is followed by the significant augmentation of REM sleep : (2) REM sleep deprivation, prior to learning or immediately thereafter, impairs the formation of a permanent memory/learning : (3) there is a vulnerable period of time(eg, REM sleep "window") following succussful learning, during which REM sleep deprivation results in memory impairment : (4) theta rhythm which develops during REM sleep induces long-term potentiation in hippocampus : (5) there are some evidences providing the relationship of neurotransmitter systems to the maintenance of REM sleep and memory storage processes.

• Smart Media Journal
• /
• v.10 no.1
• /
• pp.63-69
• /
• 2021

When a person sees a sentence and understands the sentence, the person understands the sentence by reminiscent of the main word in the sentence as an image. Text-to-image is what allows computers to do this associative process. The previous deep learning-based text-to-image model extracts text features using Convolutional Neural Network (CNN)-Long Short Term Memory (LSTM) and bi-directional LSTM, and generates an image by inputting it to the GAN. The previous text-to-image model uses basic embedding in text feature extraction, and it takes a long time to train because images are generated using several modules. Therefore, in this research, we propose a method of extracting features by using the attention mechanism, which has improved performance in the natural language processing field, for sentence embedding, and generating an image by inputting the extracted features into the GAN. As a result of the experiment, the inception score was higher than that of the model used in the previous study, and when judged with the naked eye, an image that expresses the features well in the input sentence was created. In addition, even when a long sentence is input, an image that expresses the sentence well was created.

• Journal of Fisheries and Marine Sciences Education
• /
• v.25 no.4
• /
• pp.878-890
• /
• 2013

The purpose of this study is to apply the PEOE class model that can enhance students' scientific creative problem-solving ability and self-directed learning ability in the middle school science subject and analyze the effects of it on students' long- and short-term retention, scientific creative problem-solving ability, and self-directed learning characteristics. And the paper has gained the following results: First, according to the result of analysis through the pre-test, post-test, and delay test to examine the effects of PEOE-based class on learners' long- and short-term retention, it is found to be statistically significant in the significant level of .05. In other words, the class using PEOE influences learners' short-term retention significantly, but it is even more effective in transmitting the concept that students acquire into their long-term memory. Second, according to the result of analysis through the pre-test and post-test to examine the effects of PEOE-based class on learners' scientific creative problem-solving ability, it is found to be statistically significant in the significant level of .05 in general. However, 'elaboration' and 'originality', the subfactors of scientific creative problem-solving ability, do not indicate significant effects. Third, according to the result of analysis through the pre-test and post-test to examine the effects of PEOE-based class on learners' self-directed learning characteristics, it is found to be statistically significant in the significant level of .05 as a whole. However, 'openness' and 'future-oriented self-understanding', the subfactors of self-directed learning characteristics, do not exert significant effects. Based on the above study results, it can be concluded that PEOE-based class is more effective for learners' academic achievement in science, scientific creative problem-solving ability, and self-directed learning characteristics than lecture-method instruction regarding the middle school science unit of 'The Properties of Air and Weather Change'.

• Journal of Advanced Navigation Technology
• /
• v.23 no.6
• /
• pp.561-569
• /
• 2019

Solar photovoltaic can provide electrical energy with only radiation, and its use is expanding rapidly as a new energy source. This study predicts the short and long-term PV power generation using actual converter output data of photovoltaic system. The prediction algorithm uses multiple linear regression, support vector machine (SVM), and deep learning such as deep neural network (DNN) and long short-term memory (LSTM). In addition, three models are used according to the input and output structure of the weather element. Long-term forecasts are made monthly, seasonally and annually, and short-term forecasts are made for 7 days. As a result, the deep learning network is better in prediction accuracy than multiple linear regression and SVM. In addition, LSTM, which is a better model for time series prediction than DNN, is somewhat superior in terms of prediction accuracy. The experiment results according to the input and output structure appear Model 2 has less error than Model 1, and Model 3 has less error than Model 2.

• Journal of the Korea Society of Computer and Information
• /
• v.21 no.5
• /
• pp.1-10
• /
• 2016

Magnetic disks have been used for decades in auxiliary storage devices of computer systems. In recent years, the use of NAND flash memory, which is called SSD, is increased as auxiliary storage devices. However, NAND flash memory, unlike traditional magnetic disks, necessarily performs the erase operation before the write operation in order to overwrite data and this leads to degrade the system lifetime and performance of overall NAND flash memory system. Moreover, NAND flash memory has the lower endurance, compared to traditional magnetic disks. To overcome this problem, this paper proposes EPET (Enhanced Prediction and Elapsed Time) wear leveling technique, which is especially efficient to portable devices. EPET wear leveling uses the advantage of PET (Prediction of Elapsed Time) wear leveling and solves long-term system failure time problem. Moreover, EPET wear leveling further improves space efficiency. In our experiments, EPET wear leveling prolonged the first bad time up to 328.9% and prolonged the system lifetime up to 305.9%, compared to other techniques.