• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1616-1625
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• 2019

Measuring occurrence times of random events, aimed to determine the statistical properties of the governing stochastic process, is a basic topic in science and engineering, and has been the subject of numerous mathematical modeling approaches. Often, true statistical properties deviate from measured properties due to the so called dead time phenomenon, where for a certain time period following detection, the detection system is not operational. Understanding the dead time effect is especially important in radiation measurements, often characterized by high count rates and a non-reducible detector dead time (originating in the physics of particle detection). The effect of dead time can be interpreted as a suitable rarefied sequence of the original time sequence. This paper provides a limit theorem for a high rate (diffusion-scale) counter with extendable (Type II) dead time, where the underlying counting process is a renewal process with finite second moment for the inter-event distribution. The results are very general, in the sense that they refer to a general inter arrival time and a random dead time with general distribution. Following the theoretical results, we will demonstrate the applicability of the results in three applications: serially connected components, multiplicity counting and measurements of aerosol spatial distribution.

• Physical Therapy Korea
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• v.7 no.2
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• pp.35-54
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• 2000

The purposes of this study were to assess variation of body sway prior to and after submaximal treadmill exercise; to determine the time course of the effects of a fatiguing performed on a treadmill on body sway; and to compare position sense prior to and after exercise in order to assess any variance in proprioception caused by submaximal treadmill exercise. The subjects were twenty-four healthy men in their twenties. They stood barefoot on the Kinesthetic Ability Training Balance Platform to measure body sway. Control trials were performed with eyes alternately open and closed. In the eyes open condition, they were asked to look at a target placed at eye level 1 m in front them. A total of 10 trials, each lasting 20 seconds, were performed. After this series of trials, position sense was measured. Subjects then exercised on the treadmill until 85% of each person's maximal heart rate was reached. The first series of postural sway measurements began immediately after this exercise. The second identical series of postural sway trials was performed at approximately 10 minutes after exercise. The third series was performed approximately 20 minutes after exercise. This allowed approximately 5 minutes of rest between each experimental series. Position sense was measured at approximately 15 and 25 minutes after exercise. The results were as follows: 1) There was a significant increase in body sway after submaximal treadmill exercise compared to pre-exercise values under both visual conditions (p<.05). 2) After submaximal treadmill exercise, under the eyes open condition, the mean value of body sway was significantly increased after both the first and second series (p<.05). Under the eyes closed condition, the mean value of body sway increased significantly after the first series but decreased significantly after the third series (p<.05). 3) Position sense, measured repeatedly after submaximal treadmill exercise, did not change significantly with respect to pre-exercise values (p>.05). These results suggest that fatigue induced by submaximal treadmill exercise produced an increase in body sway in young healthy subjects with or without visual input, but the increase appeared to be lasting less than 15 minutes. No significant change in position sense suggested that proprioception was unaffected by submaximal treadmill exercise-induced fatigue.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.19-26
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• 2006

In this study, psychological assessment was carried out to investigate the driver's psychological characteristics by the change of the headlight. The participants were 20 men and 20 women in their 20s and thirty-two different conditions in combinations of waveform of light, voltage, and alteration time were used. The questionnaire for the assessment was evaluated by 8 subjective item and 5-point SD criteria of 19 pair's adjective. The results were as follows : 1. The assessment results from SD method indicated 4 factors by factor analysis, and it was shown that A waveform had significances in a sense of security and impetus and B waveform had a significance in a sense of security. The levels of the limitations for the voltage change were 12[V] in the factor of a sense of security and 11[V] in the factor of a sense of impetus for A waveform, 12.6[V] in the factor of a sense of security for B waveform. 2. The results of the subjective assessment showed that the limitation of A waveform's brightness change was 12[V]. Moreover, the limitations of voltage changes were 12.67[V] for B waveform brightness change, 12.12[V] for discomfort, 12.71[V] for darkness. And the limitation of C waveform's brightness change was 12[V].

• Journal of the Korean Society for information Management
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• v.17 no.4
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• pp.7-26
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• 2000

This study is an attempt to analyze the individual merit of the INSTRAT model, which forms a cognitive process paradigm, and that of the Big6 model, which involves a functional approach, as tools for enhancing human information activities and aptitude. The former was examined through logical interpretations, while the latter was deduced from interviews using the Micro-Moment Time-Line method, a key methodology used in the Sense-Making Approaches. Results indicate that the application of the INSTRAT model is suitable for developing information systems that can assist users in the stage of defining information needs and search strategies, and that the application of the Big6 model is appropriate in information literacy education or information aptitude training. Of particular significance is the fact that the study proves for the first time that human information problem-solving behavior indeed follows the process delineated in the Big6 model.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.293-299
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• 2023

In recent years, with the rapid development of real-time rendering technology, the quality of the images produced by real-time rendering has been improving, and its application scope has been expanded from games to animation and advertising and other fields. This paper analyses the development status of real-time rendering technology in 3D animation by investigating the 3D animation market in China, which concludes that the number of 3D animations in China has been increasing over the past 20 years, and the number of 3D animations using real-time rendering has been increasing year by year and exceeds that of 3D animations using offline rendering. In this study, a real-time rendering and offline rendering 3D animation are selected respectively to observe the screen effect of characters, special effects and environment props, and analyse the advantages and disadvantages of the two rendering technologies, and finally conclude that there is not much difference between real-time rendering 3D animation and offline rendering 3D animation in terms of quality and the overall sense of view, and due to the real-time rendering of the characteristics of the WYSIWYG, the animation designers can better focus on the creation of art performance. Real-time rendering technology has a good development prospect and potential in 3D animation, which paves the way for designers to create 3D content more efficiently.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.2
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• pp.421-440
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• 2010

Our country has excessive amount of learning per hour compared with Japan and Singapore. And as there is no consistence for definition of time between grades, it deteriorates understanding of students. Our country teaches students focusing on time algorism whereas Japan and Singapore teaches their students focusing on flow of time. In composing of mathematics textbook in Korea, Japan and Singapore, textbook of our country contains far more of learning compared with the amount designated in textbooks. Textbooks of Japan contains less teaching elements, but instead it contains much activities to expedite time sense As time is distributed in activities of students, it is more important to construct textbooks with experience of students rather than algorism approaches. In addition, textbooks of Singapore contains various examples and clarified concepts compared with those of our country. Like above, time teaching deployment methods of Japan and Singapore gives us good lessons for teaching time in our country, and it is expected be good reference for future development of our textbooks.

• Communications for Statistical Applications and Methods
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• v.18 no.3
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• pp.319-331
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• 2011

In this paper, we propose automatic procedures for the model selection of various univariate time series data. Automatic model selection is important, especially in data mining with large number of time series, for example, the number (in thousands) of signals accessing a web server during a specific time period. Several methods have been proposed for automatic model selection of time series. However, most existing methods focus on linear time series models such as exponential smoothing and autoregressive integrated moving average(ARIMA) models. The key feature that distinguishes the proposed procedures from previous approaches is that the former can be used for both linear time series models and nonlinear time series models such as threshold autoregressive(TAR) models and autoregressive moving average-generalized autoregressive conditional heteroscedasticity(ARMA-GARCH) models. The proposed methods select a model from among the various models in the prediction error sense. We also provide an R package autots that implements the proposed automatic model selection procedures. In this paper, we illustrate these algorithms with the artificial and real data, and describe the implementation of the autots package for R.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.4
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• pp.289-294
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• 2011

Digital redesign is yet another efficient tool to convert a pre-designed analog controller into a sampled-data one to maintain the analog closed-loop performance in the sense of state matching. A rising difficulty in developing a digital redesign technique for trackers with time-varying references is the unavailability of a closed-form discrete-time model of a system, even if it is linear time-invariant. A way to resolve this is to approximate the time-varying reference as a piecewise constant one, which deteriorates the state matching performance. Another remedy may be to decrease a sampling period, which however could numerically destabilize the optimization-based digital redesign condition. In this paper, we develop a digital redesign condition for time-varying trackers by approximating the time-varying reference through a triangular hold and by introducing delta-operated discrete-time models. It is shown that the digitally redesigned sampled-data tracker recovers the performance of the pre-designed analog tracker under a fast sampling limit. Simulation results on the formation flying of satellites convincingly show the effectiveness of the development.

• Investigative Magnetic Resonance Imaging
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• v.25 no.4
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• pp.252-265
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• 2021

Cardiac magnetic resonance imaging (MRI) serves as a clinical gold-standard non-invasive imaging technique for the assessment of global and regional cardiac function. Conventional cardiac MRI is limited by the long acquisition time, the need for ECG gating and/or long breathhold, and insufficient spatiotemporal resolution. Real-time cardiac cine MRI refers to high spatiotemporal cardiac imaging using data acquired continuously without synchronization or binning, and therefore of potential interest in overcoming the limitations of conventional cardiac MRI. Novel acquisition and reconstruction techniques must be employed to facilitate real-time cardiac MRI. The goal of this study is to discuss methods that have been developed for real-time cardiac MRI. In particular, we classified existing techniques into two categories based on the use of non-iterative and iterative reconstruction. In addition, we present several research trends in this direction, including deep learning-based image reconstruction and other advanced real-time cardiac MRI strategies that reconstruct images acquired from real-time free-breathing techniques.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.638-647
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• 2011

Various approaches directly using vibrations of speakers have been suggested to effectively display the aural information such as the music to the hearing-impaired or the deaf. However, in these approaches, the human can't sense the frequency information over the maximum perceivable vibro-tactile frequency (around 1kHz). Therefore, in this study, an approach via spectral modulation of compressing the high frequency audio information into perceivable vibro-tactile frequency domain and outputting the modulated signals through the designated speakers is proposed. Then it is shown, through simulations of using Short-Time Fourier Transform (STFT) with Hanning windows and through preliminary experiments of using the vibro-tactile display testbed which is built and interfaced with a notebook PC, that the modulated signal of a natural sound composing sounds of a frog, a bird, and a water stream could produce the noise-free signal suitable enough for vibro-tactile speakers without causing Significant interfering disturbances, Lastly, for three different combinations of information provided to the subject, that is, i) with only video image, ii) with video image along with the modulated vibro-tactile stimuli as proposed in this study to the forearm of the subject, and iii) with video image along with full audio information, the effects to the human sense of reality and his emotion to given audio-video clips including various sounds and images are investigated and compared. It is shown from results of those experiments that the proposed method of providing modulated vibro-tactile stimuli along with the video images to the human has very high feasibility to transmit pseudo-aural sense to the human.