• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.3
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• pp.1-7
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• 2010

Cognitive Radio, which adaptively utilizes the vacant licensed spectrum band, is considered as an effective way to alleviate the scarcity of spectrum resource shortage. In order to guarantee the non-interference transmission of primary system, spectrum sensing, especially in quiet period, is proposed. However, it is insufficient to avoid the unacceptable interference caused by Cognitive Radios, because the primary user may appear anytime that is unpredictable. In this paper, we address the deficiency of conventional spectrum sensing and propose a novel Cognitive Radio receiver structure with monitoring function block to detect the appearance of primary user in a real-time manner. Simulations prove that the proposed eigenvalue based detection method together with the two-threshold decision procedure performs properly.

• Korean Journal of Childcare and Education
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• v.9 no.5
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• pp.335-355
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• 2013

The purpose of this study was to investigate children's recognition and needs about rest and naps at child care education centers, in the view of respecting children's rights. The participants were 40 children(20 4 year olds and 20 5 year olds), attending B Public Child Care Education Center in Seoul. The research methods were accomplished by participant observation in project activities and interviews with semi-structured questions. The collections of this process which were recorded document materials and video materials were analyzed by transcribed method. The results of this study were as follows: First, the meaning of the children's recognized rest showed time for family together, time for fun play, time required when they were very stressful and angry, and time for eating delicious meals. Second, children recognized that nap time in the child care center was time for a forced nap, time for listening to quiet music, and time for feeling good after a nap. Third, as for the needs to take a rest and a nap for children, they wanted to rest when they came together at full day class after their friends had returned home, they wanted a special area except the classroom, and they wanted to be cared for by familiar adults. Based on these results of the study, future research directions were proposed in terms of respecting children's rights of enjoying a rest and a nap.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1950-1956
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• 1997

An engineering goal in vibration and noise professionals is to develope quiet machines at the preliminary design stage, and various numerical techniques such as FEM, SEA or BEM are one of the schemes toward the goal. In this paper, the research has been focused on the sensitivity effect of mesh sizes for FEM application so that the optimum size of the mesh that leads to engineering solution within acceptable computing time could be generated. In order to evaluate the mesh size effect, three important parameters have been examined : natural frequencies, number of modes and driving point mobility. First, several lower modes including the fundamental frequency of a 2-D plate structure have been calculated as mesh size changes. Since theoretical values of natural frequencies for a simple structure are known, the deviation between the numerical and theoretical values is obtained as a function of mesh size. The result shows that the error is no longer decreased if the mesh size becomes a quarter wavelength or smaller than that. Second, the mesh size effect is also investigated for the number of modes. For the frequency band up to 1.4 kHz, the structure should have 38 modes in total. As the mesh size reaches to the quarter wavelength, the total count in modes approaches to the same values. Third, a mobility function at the driving point is compared between SEA and FEM result. In SEA application, the mobility function is determined by the modal density and the mass of the structure. It is independent of excitation frequencies. When the mobility function is calculated from a wavelength to one-tenth of it, the mobility becomes constant if the mesh becomes a quarter wavelength or smaller. We can conclude that dynamic parameters, such as eigenvalues, mode count, and mobility function, can be correctly estimated, while saving the computing burden, if a quarter wavelength (.lambda./4) mesh is used. Therefore, (.lambda./4) mesh is recommended in structural vibration analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.904-908
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• 2008

As the various industrial production machinery has come into being by development of industrial technology, the productivity of the basic industrial production machinery has improved and the international competitiveness of the one of Korea has strengthened. However, at the same time, noise from various industrial production machinery disturbs the quiet environment. There are 35 kinds of the noise emission machinery defined in the noise and vibration control act according to the horse power and the number of machinery. These were classified in 1992 through investigation from 1990 to 1991, and the characteristic of the noise emission machinery may be different from the past one. So we need to investigate the characteristics of the noise emitted by machinery to control it rightly. Also we need to investigate the new noise emission machinery which has come into being recently. In this survey, we measured sound intensity of 32 noise emission machinery to calculate the sound power levels of those and investigated the characteristic of the sound power level of those according to the frequency. From the survey, we found that the forging machine, concrete pipe and pile making machine, sawing machine, etc. are the noisy machinery. And the automatic packing machine, sewing machine, centrifuge, etc. are the silent machinery. Also the generator, the concrete pipe and pile making machine, the printing machine, etc. emit the low frequency noise, and the molding machine, the stone cutter, the metal cutter, etc. emit the high frequency noise. Lastly, we intented to propose the proper guide line of classifying noise emission machinery.

• Asian Journal for Public Opinion Research
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• v.5 no.2
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• pp.143-174
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• 2018

A cultural exchange program widens the horizons of students. It gives them the opportunity to associate with other societies and learn their cultures at the same time. This program also serves as a training ground where students enhance their skills, acquire learnings, and gain experiences that will help them in their future careers and make them more competitive than others. Hence, the objective of this study is to come up with an output from a set of guidelines established and gathered from the different "work and travel" experiences of the participants. This study adopted the phenomenological and was conducted in places that are relatively quiet for recording, and suitable and convenient for both the researchers and participants. The researchers gathered data through in-depth interviews of samples gathered through snowball sampling. Cellphones were used to record interviews. At the end of the thematic analysis of information, the researchers came up with three major categories which included: (1) 'having the opportunity to know the industry well and improve one's capability', 'undergoing different cultural exchange experiences for better development', and 'being able to practice intercultural immersion'. Some of the researchers' recommendations would be to institute a feedback mechanism such as personal interviews, monitoring visits, etc. and use the output, a set of guidelines, that would help the future 'work and travel' participants to prepare and anticipate the program they would undergo.

• Journal of Korean Academy of Nursing
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• v.29 no.6
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• pp.1304-1313
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• 1999

Breathing is essential for life and at the same time takes a role as a antidote for stress. In the Orient, it was recognized early that respiration, mind, and body have a relation that is inseparable and therefore proper breathing is so important. However, since the mechanism of therapeutic effect by breathing have not been verified, the treatment has been continued till recent years. From that which originated in the Orient, several techniques in the west have been developed to regulate breathing, and have been applying to the clinical situation and to studies, however scientific studies are still lacking. Recently, relaxed breathing has been used as an efficient strategy for breathing therapy as it has an effect on reducing physiological tension and arousal, and, therefore can be used as a basic technique to control or manage stress. In this study, in order to provide basic information and guidelines for clinical application, which will aid in the application of the theoretical basics of breathing therapy and its technique, a review of the literative was conducted. The findings are as follows: 1. Since proper breathing not only has, physically, the important function in supplying oxygen to the body but also gives a good emotional, or pleasant state of mind, it is the first step in controlling physical and mental health. 2. The basic types of breathing can be classified into two types; ‘diaphragmatic breathing(relaxed breathing)’ and ‘chest breathing(stress breathing)’. In yoga type breathing, there are four kinds of breathing, ‘upper breathing’, ‘mid breathing’, ‘down breathing’, and ‘complete breathing’. 3. The theoretical explanation of the positive thera peutic effect of breathing therapy techniques exemplifies good brain function, sufficient air flow through the nasal passages, diaphragmatic movement, light vagal stimulation, CO2 changes and cognitive diversion but in most studies, the hypothesis of CO2 is supported. 4. The technique of breathing is designated with many names according to the muscles and techniques used for breathing, and for control of stress, diaphragmatic breathing(relaxed breathing) is explained as a basic technique best used to manage of stress. 5. The relaxed-breathing includes slow diaphragmatic breathing, breath meditation, nasal breathing, yogic abdominal breathing, Benson's relaxed response, and quiet response.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1018-1024
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• 2010

The printer noise consists of the noise of the various components and parts such as motor, fan and solenoid. And the human's printing sound recognition shows various aspects when the printer starts to print papers because the components operate at the same time. Especially, printers are usually installed in the quiet office room. Therefore the printing noise is related to its competitiveness in the market. The importance of the printer sound qualities is increasing and it is necessary to develop the sound quality evaluation system, so it is a key point to identify the noise source of the printer and develop the sound quality index to each component. By using this evaluation system, it is possible to evaluate the sound quality of a prototype printer compared to the already existing one. In this paper, the printer sound quality evaluation system was developed by the following steps. Firstly, the signal processing method was applied to the recorded printing sound to identity and split the noise of components. Secondly, the MLR(multiple linear regression) method and the psychoacoustics were used to develop the sound quality index. Finally, the improvement of the printer sound quality is possible by using the result of the MLR and the path analysis. The output of this research will be applied to the development of a new printer.

• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.251-259
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• 1996

This study was conducted to find out whether information based on norm activation theory affects personal norm and rule-violating behavior in a recreation setting, using the data collected from the Second Campground in Chiri-Mountain National Park in 1994. Of the total 280 questionnaires distributed, 253(90.4%) were usable for data analysis. Results showed that information did not increase awareness of consequences(AC) of their actions or ascription of responsibility(AR) for acts and consequences to themselves, and did not directly decrease the quiet time rule-violating behavior. However, it was found that respondents with high ACR(combination of AC and AR) or personal norms less violated the rule. Management implications of these findings were discussed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.219-224
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• 2017

These days, it is developed renewable energy-based wind power technology. Wind power generation is relatively quiet, and environmental damage is relatively low. In developed countries, a lot of wind power generation is being built. In Korea, the generation efficiency is low because there are few areas where the wind speed is maintained for four seasons. In recent years, forest damage, low noise, and environmental degradation complaints are frequent. In this paper, we performed an experiment to manage pitch control effectively by analyzing wind, direction, and temperature in real time based on FUZZY rule and cluster analysis.Using the new algorithm proposed by the simulation results, we could verify the efficiency of wind power generation pitch control for wind condition and direction condition by using the pitch control analysis technique.Furthermore, visualization representations have proven to automatically analyze early warning and efficiency of generator performance.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.31.4-32
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• 2016

Observing the solar atmosphere with ground-based telescopes in the near-infrared has a number of advantages when compared to classical measurements in visible wavelengths. One of them comes from the magnetic sensitivity of spectral lines, which varies as ${\lambda}_g$, where g is the effective $Land{\acute{e}}$ factor of the transition. This wavelength dependence makes the near-infrared range adequate to study subtle spatial or temporal variations of the magnetic field. Spectral lines, such as the photospheric Fe I $1.5648{\mu}m$ spectral line, with a $Land{\acute{e}}$ factor g=3, have often been used in the past for this type of studies. To study the chromosphere, the Ca II IR triplet and the He I $1.0830{\mu}m$ triplet are the most often observed lines. The latter has the additional advantage that the photospheric Si I $1.0827{\mu}m$ is close enough so that photosphere and chromosphere can be simultaneously recorded with a single detector in a spectrograph. The instrument TIP (Tenerife Infrared Polarimeter) has been continuously operating since 1999 at the 70-cm German VTT of the Observatorio del Teide and has been recently moved to the 1.5-m German GREGOR. During all this time, results have been obtained concerning the nature of the weak photospheric magnetic field of the quiet sun, magneto-acoustic wave propagation, evolution with the cycle of sunspot magnetic fields, photospheric and chromospheric magnetic field in emerging regions, magnetic field in chromospheric structures such as filaments, prominences, flares, and spicules, etc. In this talk, I will review the main results obtained after all these observations and mention the main challenges for the future. With its novel polarization-free design and a complete suite of instruments aimed at simultaneous (imaging and spectroscopic) observations of the solar photosphere and chromosphere, the EST (European Solar Telescope) will represent a major world-wide infrastructure to understand the physical nature of all these phenomena.