• Sleep Medicine and Psychophysiology
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• v.19 no.1
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• pp.11-17
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• 2012

Objective: Among various methods developed to quantitatively explore electroencephalograms (EEG), we focused on a wavelet method that was known to yield robust results under nonstationary conditions. The aim of this study was thus to introduce the wavelet method and demonstrate its potential use in clinical sleep studies. Method: This study involved artificial EEG specifically designed to validate the wavelet method. The method was performed to obtain time-dependent spectral power and phase angles of the signal. Synchrony of multichannel EEG was analyzed by an order parameter of the instantaneous phase. The standard methods, such as Fourier transformation and coherence, were also performed and compared with the wavelet method. The method was further validated with clinical EEG and ERP samples available as pilot studies at academic sleep centers. Result: The time-frequency plot and phase synchrony level obtained by the wavelet method clearly showed dynamic changes in the EEG waveforms artificially fabricated. When applied to clinical samples, the method successfully detected changes in spectral power across the sleep onset period and identified differences between the target and background ERP. Conclusion: Our results suggest that the wavelet method could be an alternative and/or complementary tool to the conventional Fourier method in quantifying and identifying EEG and ERP biomarkers robustly, especially when the signals were nonstationary in a short time scale (1-100 seconds).

• Journal of The Korean Association For Science Education
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• v.35 no.3
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• pp.499-508
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• 2015

The purposes of this study are to investigate elementary students' perception of science classroom through an analysis of students' answer to an open-ended question and to suggest a framework for the analysis of science classroom culture, as the first step to develop an analysis tool for qualitative exploration of science classroom culture. We analyzed 571 responses and developed an analysis framework with six categories (i.e. major factors; power structure of a classroom community; focused domains of the science classroom; student concerns; atmosphere of science classroom; participation form). The details of the six categories can be summarized as follows: (1) major factors were revealed to be practical work, fun, teacher, community and others; (2) the power structure of classroom community was in the order of peer students, teacher, and individual student himself/herself; (3) the focused domains of the science classroom perceived by students were more about affective and behavioral domains than cognitive one; (4) major student concerns were teachers' teaching, having practical work, and the understanding of and the sharing of knowledge and opinions (5) science classroom atmosphere was noisy and pranky but fun and interesting; (6) the students participation forms were to be total participation or voluntary participation or cooperative practice. Through this study, not only suggesting the framework, but we could also get implications for the cultural aspects of science classroom based on the results of data analysis in this study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.977-983
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• 2007

Recently, the number of systems which utilize wireless power transmission to a receiving module in a short distance is increasing. For efficient use of receiving space, coils are wound around the ferrite core to produce electromotive force(emf) in suppling power by wireless transmission. This paper analyzed the magnetic flux density distribution in the ferrite core in magnetic field environment which is uniformly oriented along to a single axis at 125kHz. For numerical analysis, Ansoft Maxwell which is applying the FEM(Finite Element Method) method was used. We studied the variations of the gathered magnetic fluxes to the changes of the relative permeabilities of the ferrite cores. Also we calculated the magnetic flux variation by shaving the ferrite core off for the groove of coil winding. Results showed that using a small ferrite core in magnetic field at 100kHz band can increase the amount of magnetic flux $3{\sim}4 times$ than without the core. The magnetic flux decreased 23% by shaving the core 0.5 mm on the periphery of 4.75 mm radius core with the relative permeability 800.

• Journal of Acupuncture Research
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• v.25 no.6
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• pp.109-116
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• 2008

Objectives : This study investigated the effect of imbalance of autonomic nerve system on the idiopathic facial palsy by the comparison Heart Rate Variability results of Facial palsy group and healthy control group, and to clarify correlation between House-Brackmann Grade and Heart Rate Variability results. Methods : 119 idiopathic facial palsy patients and 88 health subjects who underwent HRV test were retrospectively reviewed based on medical records. We compared between the HRV results of facial palsy group and that of normal control group, and also compared the HRV results of facial palsy subgroup classified by House-Brackmann Grade. Results 1. All HRV results－Mean Heart Rat(MHRT), Standard Deviation of all the Normal RR intervals(SDNN), Total Power(TP), Very Low Frequency(VLF), Low Frequency(LF), High Frequency(HF), ratio betwween the Low Frequency and High Frequency power(LF/HF ratio) of facial palsy group are decreased compared to that of normal control group, especially SDNN, TP, VLF, LF, LF/HF ratio showed significant difference(p<0.05). 2. HRV results showed no significant correlation in House-Brackmann Grade. Conclusions : This study showed that lower HRV results of facial palsy group than normal control group and suggests that imbalance of autonomic nerve system related with facial palsy. HRV could be a objective tool to reflect condition of idiopathic facial palsy patients.

• Journal of Korean Academy of Nursing
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• v.26 no.3
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• pp.709-729
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• 1996

This study was done to analyze the trends of research on coping in Korea, to suggest future direction, for research on coping, and ultimately to contribute to an increase in explanation of adaptation. This article reviewed 79 nursing research papers on coping done since 1978 by examining them according to the period of publication or presentation, research design, type of subjects, measurement instruments, research for a degree or not, range of reliability, and association of coping and related variables. The results are as follows : The number of studies on coping increased rapidly from the mid-1980's and decreased slowly from the mid-1990's. The maority of the studies were surveys, comparative studies, or correlational studies. The subects of the 46 studies were healthy people, while those in the remaining studies were patients with a variety of illnesses. Thirth-eight studies on coping were done for master's thesis, three for dissertion, and 38 were not degrees. The Bell and Jalowiec coping scales have not been used since the early 1990's. In contrast, Lazarus and Folkman's W.C.C.L. has been used increasingly since that time. The reliabilities of the coping scale were reported in 37 cases and the Cronbach's alpha coefficients were .71 to .86. All subjects reported using more problem-oriented coping than emotion-oriented coping in short-term or emotion-oriented coping and healthy groups did more long-term coping. It was difficult to describe consistently the relationship between stress and coping according to the type of coping scale or research subjects, but generally moderate relationships were found. This was due to instrumental problems and no consideration of situational context. The subject group who used more short-term coping and less long-term coping reported poorer mental status, and higher scores in burnout and state anxiey than others. That is, the relationship between stress and adaptation increased the power of explanation with intervening the mediating effect of coping. The association of locus of control, mastery, social support, and self-concept with coping showed positive relationships : those of uncertainty and severity in illness with coping showed negativerelationships ; those of state anxiety and depression with short-term coping were positive, and those of self-esteem with long-term coping or problem-oriented coping were negative. There were significant differences in the scores of types of coping according to religion, level of education, and socio-economic status. That is, Presbyterians and Catholics, those with higher education levels and higher socio-economic status used more long-term or problem-oriented coping. On the basis of the above findings the following recommendations are made : 1. There is a need to test the mediating effect of coping variable in order to clarify the concept. 2. Longitudinal studies are needed to determine the patterns of change in coping strategies when stressful events are encountered. 3. It's necessary to develop a reliable and variable measurement tool for coping. 4. There is a need to identify subscales of coping to increase explanation of variance 5. It's necessary to consider personal, situational, and antecedent variables : the characteristics of subject populations, the natures of illness and treatment situations. 6. The power of explanation of studies designed to identify the stress-adaptation process should be increased using the combination model of process-oriented coping and cognitive-structural model.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.423-431
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• 2011

Recentincreasing awareness of the environmental damage caused by the $CO_2$ emission of fossil fuelsstimulated the interest in alternative and renewable sources of energy. Fuel cell is a representative example of hydrogen energy utilization. In this study, Molten Carbonate Fuel Cell system is simulated by using $Aspen^{TM}$. Stack model is consisted of equilibrium reaction equations using $ACM^{TM}$(Aspen Custom Modeler). Balance of process of fuel cell system is developed in Aspen $Plus^{TM}$ and simulated at steady-state. Analysis of performance of the system is carried out by using sensitivity analysis tool with main operating parameters such as current density, S/C ratio, and fuel utilization and recycle ratio.In Aspen $Dynamics^{TM}$, dynamics of MCFC system is simulated with PID control loops. From the simulation, we proposed operation range which generated maximum power and efficiency in MCFC power plant.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.6
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• pp.50-55
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• 2011

The fluid power products are widely used in current industrial area such as automation of products and equipment assembly, high-tech machine tool, aircraft, train, and etc. As the development of industry is in progress, the development of the fluid power products is demanding and it is required in every industrial area. This research proposed a pneumatic system to evaluate displacement accuracy of the pneumatic actuator without external load and to analyze capability of integration of the valve system. The pneumatic system consisted of a combination of pneumatic actuator, four two-port valves, two three-port valves, two pressure valve, a check valve, two proximity sensors, and a program logic controller (PLC). The position controller is based on the PLC connected with the proximity sensors. The maximum air pressure applied for tests was $49.05N/cm^2$ and the displacement accuracy of a stroke was measured using a dial gauge. The supply- and discharge-side of air pressure and the length of the stroke of the pneumatic cylinder were varied The test of the position control of the pneumatic cylinder was carried out 50 times at each supply- and discharge-side air pressure of 24.53/34.34, 29.43/39.24, 34.34/44.15, and $39.24/49.05N/cm^2$ and replicated three times. The accuracy of the displacement of the pneumatic cylinder stroke increased as the supply- and discharge-side of air pressure increased with the stroke length of 133mm. Also the displacement accuracy increased as the stroke length increased with the fixed supply- and discharge-side of air pressure of the pneumatic cylinder as 34.34 and $44.15N/cm^2$, respectively. The most accurate displacement of the pneumatic cylinder was obtained at the supplyand discharge-side of air pressure of 39.24 and $49.05N/cm^2$, respectively, and strokes of 170 and 190mm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.489-492
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• 2014

This thesis provides the design of system software for the management of radiation dose that is generated using computer tomography(CT). Because radiation exposure is different depending on the difference in sensitivity to each part for each of the patient's body, if we will be able to manage an appropriate amount of radiation, it is possible to estimate the radiation exposure of the patient as a result. Recently, radiation leakage incident of Japanese nuclear power plant was in the news internationally and there is a growing interest not only a nuclear power plant, to medical radiation exposure. In spite of the fact that currently safety management of radiation is under control only the workers of the radiation involved, exposure management of patients until now have been required. Surgery and inspection using the radiation in Korea will increase, due to this medical exposure has increased, but it is a reality that medical institution don't know the level of radiation exposure applied to the patient. Therefore a system for managing the radiation exposure of the patient from the medical institution is required. This paper proposes a design of a software program to manage the radiation exposure of CT is an typical imaging tool to use the radiation in the medical institution. By check the amount of radiation dose and set the limit of dose, we would help to optimize the medical exposure of the patient.

• Particle and aerosol research
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• v.16 no.4
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• pp.107-117
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• 2020

Based on the airborne measurement results over a coal fired power plant and steel work in Dangjin city, SO2 emission amounts of each site are estimated (top-down emission). Airborne measurements were carried out on May-June and October-November 2019. The estimated SO2 emission in 2019 for the power plant was 1502.1 kg/hr and that for the steel work was 2850.5 kg/hr, higher as much as a factor of 2.5 and 2.0, respectively, than the emission amounts provided by both facilities (bottom-up emission). The outcomes strongly illustrates that well designed airborne observations can serve a quantitative diagnostic tool for bottom-up emission estimates. Further research direction to improve the reliability of the top-down emission estimates is suggested.

• The Journal of Korean Institute of Next Generation Computing
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• v.14 no.6
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• pp.44-56
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• 2018

Researches on military weapons are actively studied to improve national defense power of each country. The military weapon system is being used not only as a weapon but also as a reconnaissance and surveillance device for places where it is difficult for people to access. If such a weapon system becomes an object of attack, military data that is important to national security can be leaked. Furthermore, if a device is taken, it can be used as a terrorist tool to threaten its own country. So, security of military devices is necessarily required. In order to enhance the security of a weapon system such as drone, it is necessary to form a chain of trust(CoT) that gives trustworthiness to the overall process of the system from the power on until application is executed. In this paper, by analyzing the trusted computing-based boot technology, we derive trusted boot technology components and classify them based on hardware dependence/independence. We expect our classification of hardware dependence/independence to be applied to the trusted boot technology of our self-development ultraprecision weapon system to improve the defense capability in our military.