• 전자공학회논문지A
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• 제30A권11호
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• pp.105-112
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• 1993

Oxide and reoxidized-nitrided-oxide were formed by furnace oxidation and rapid thermal processing (RTP). MOS capacitor and n-MOSFET's with those films as gate insulators were fabricated. The electrical characteristics of insulators were evaluated by current-voltage, high-frequency capacitance-voltage (C-V), and time-dependent dielectrical breakdown (TDDB) measurements. The hot carrier effects of MOSFET's were also investigated. Time-dependent dielectrical breakdown (TDDB) characteristics show that the life time of reoxidized-nitrided-oxide films is about 3 times longer than that of oxides. Hot carrier effects reveal that the life time of MOSFET's with reoxidized-nitrided-oxides is about 3 times longer than that of MOSFET's with oxides. Therefore, it is found that the reliability of dielectric films estimated by the hot carrier effects of MOSFET's is consistent with that of dielectric films from TDDB method.

• 4차산업연구
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• 제4권2호
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• pp.1-9
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• 2024

Purpose: While most studies focus on learning styles in face-to-face education, research on online learning environments, especially by age in lifelong education, is limited. This study aims to propose a direction for online learning by analyzing digital literacy and e-Learning learning styles by age in lifelong education. Research design, data and methodology: The study surveyed 100 online learners from an open university in Seoul. Using an e-Learning learning styles test, frequency analysis was conducted by gender, age, and digital literacy. A learning plan was then proposed based on the results. Results: The study found no age-related differences in digital literacy. Both men and women shared similar ratios of Environment-dependent and self-directed learning styles, reflecting the characteristics of online learners using digital devices. Conclusions: In lifelong education, e-Learning design should accommodate diverse learning styles: web/app designs for Environment-independent and self-directed learners, short/long formats for Passive learners, real-time (LMS)/non-real-time (ZOOM) systems for Positive and cooperative learners, and AI/human tutors for Environment-dependent and self-directed learners.

• 한국식생활문화학회지
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• 제23권6호
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• pp.779-792
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• 2008

The consumption of a wide variety of food groups is considered one of the key components of nutritional adequacy. The 2005 Dietary Guidelines for Koreans includes the consumption of a variety of foods from diverse food groups as a component of a normal diet. A survey was conducted to evaluate the relationship between the dietary diversity of food groups and nutrient intake in elderly patients (age 65 and above) at a rural area in Korea (Inje). 296 subjects (111 male and 185 female) were probed in a 3 day 24-recall dietary survey. Subjects were grouped according to food group intake frequency, based on six food groups (grain, meat/fish/legume/egg, vegetable, fat/oil, dairy, fruit). Nutritional quality was evaluated according to the numbers of nutrients under EAR (Estimated Average Requirements), and MAR (mean adequacy ratios). The frequency of elderly subjects consuming a meat/fish/legumes/egg food group less than once per day was 29.4%. The frequency of elderly subjects consuming fat/oil food group less than once per day was 65.8%. The percentage of subjects who did not eat dairy food was 88.8%, and that of subjects who did not eat fruit was 57.5%. A stepwise multiple regression analysis was used to develop models relating nutritional quality to possible food group intake frequency factors. Using the number of nutrients under EAR as a dependent variable, the meat/fish/legume/egg food group intake frequency explained 9.9% of variance, followed by the grain group, fat/oil group, dairy group, and vegetable and fruit group (Model $R^2$=0.260). For mean nutrient adequacy ratio as a dependent variable, the model $R^2$ was 0.326. The results of this study suggest that a highly varied diet in elderly might be associated with better nutritional quality, as assessed by nutrient intake. Accordingly, dietary guidelines should take into consideration nutritional characteristics in order to improve intake from all major food groups and to provide a variety of foods in the diet.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.164-174
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• 1996

This paper presents control and response characteristics of a continuously variable ER(electrorheological) damper for small-sized vehicles. The ER damper is devised and its governing equation of motion is derived from the bond graph model. The field-dependent yield shear stresses are distilled from experimental investigation on the Bingham property of the ER fluid. The distilled data are incorporated into the governing system model and, on the basis of this model, an appropriate size of the ER damper is manufactured. After evaluating the field-dependent damping performance of the proposed ER damper, the skyhook control algorithm is formulated to achieve desired level of the damping force. The controller is then experimentally implemented and control characteristics of the ER damper are presented in order to demonstrate superior controllability of the damping force. In addition, response characteristics of the damping force with respect to the electric field with fast on-off frequency are provided to show the feasibility of practical application.

• 가정∙방문간호학회지
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• 제31권1호
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• pp.56-65
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• 2024

Purpose: This study aimed to explore the association between demographic characteristics, hospitalization-related characteristics, and the severity of long-term hospitalization in a high-level general hospital, and to analyze the factors influencing decisions of all patients. Methods: General and clinical characteristics of the participants were analyzed using frequency, percentage, mean, and standard deviation. Differences in these characteristics, contingent upon whether a power source was requested, were analyzed using independent t-Test and Chi-squared tests. Logistic regression analysis was used to identify the factors related to the presence or absence of power requests. Results: The factors impacting the decision to refer a dependent variable include medical treatment (neurosurgery) (B=2.118, SE=0.960, p-value=.027, OR=8.314, 95% CI=1.267-54.551), infection isolation (CRE) (B=1.336, SE=0.666, p-value=.045, OR=3.804, 95% CI=1.032-14.021), and the utilization of tertiary antibiotics (B=3.076, SE=1.362, p-value= .024, OR=21.663, 95% CI=1.502-312.530). Conclusion: This study found a significant association between medical treatment (neurosurgery), infection isolation (CRE), and the use of tertiary antibiotics as dependent variables. These findings indicate that continuous monitoring can contribute to a reduction in long-term financial burdens.

• 한국소음진동공학회논문집
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• 제11권5호
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• pp.123-130
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• 2001

The purpose of this paper is to reduce the level of idling vibration on a steering wheel. In some cases, vibration on steering wheel is amplified due to the resonance between the first natural frequency of T-beam and engine idling speed. Using SDM(structural dynamic modification) technique, T-beam is redesigned to reduce its vibration. This paper used FRF(frequency response function) synthesis technique which is entirely dependent on experiment. But this method requires lots of test efforts to enhance its reliability of design. While combining this method with an analytic method. the experimental burden, the major drawback of FRP synthesis method, can be considerably relieved. Using ana1ytic sensitivity analysis, some effective modification regions are preliminarily chosen as candidate Positions where SDM can be applied to modify T-beam\`s dynamic characteristics.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.176-181
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• 2002

The continuous Gabor wavelet transform (GWT) has been utilized as a useful time-frequency analysis tool to identify the rapidly-varying characteristics of some wave signals. In the application of GWT, it is important to select the Gabor wavelet with the optimal shape factor by which the time-frequency distribution of a signal can be accurately estimated. To find the signal-dependent optimal Gabor wavelet shape factor, the notion of the Shannon entropy which mesures the extent of signal energy concentration in the time-frequency plane is employed. To verify the validity of the present entropy-based scheme, we have applied it to the time-frequency analysis of a set of elastic bending wave signals generated by an impact in a solid cylinder.

• 한국수산과학회지
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• 제51권3호
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• pp.321-327
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• 2018

To classify seafloor sediments using a probabilistic neural network (PNN), the frequency-dependent characteristics of broadband acoustic scattering, which make it possible to qualitatively categorize seabed type, were collected from three different geographical areas in Korea. The echo data samples from three types of seafloor sediment were measured using a chirp sonar system operating over a frequency range of 20-220 kHz. The spectrum amplitudes for frequency responses of 35-75 kHz were fed into the PNN as input feature parameters. The PNN algorithm could successfully identify three seabed types: mud, mud/shell and concrete sediments. The percentage probabilities of the three seabed types being correctly classified were 86% for mud, 66% for mud/shell and 72% for concrete sediment.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.67-73
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• 2018

The paper deals with an approach to time domain simulation for closed end at the downstream of pipe, hydraulic lines terminating into a tank and series lines with change of cross sectional area. Time domain simulation of a fluid power systems containing hydraulic lines is very complex and difficult if the transfer functions consist of hyperbolic Bessel functions which is the case for the distributed parameter dissipative model. In this paper, the magnitudes and phases of the complex transfer functions of hydraulic lines are calculated, and the MATLAB Toolbox is used to formulate a rational polynomial approximation for these transfer functions in the frequency domain. The approximated transfer functions are accurate over a designated frequency range, and used to analyze the time domain response. This approach is usefully to simulate fluid power systems with hydraulic lines without to approximate the frequency dependent viscous friction.

• Advances in nano research
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• 제6권4호
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• pp.377-397
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• 2018

In the present investigation, thermal buckling and free vibration characteristics of functionally graded (FG) Timoshenko nanobeams subjected to nonlinear thermal loading are carried out by presenting a Navier type solution. The thermal load is assumed to be nonlinear distribution through the thickness of FG nanobeam. Thermo-mechanical properties of FG nanobeam are supposed to vary smoothly and continuously throughout the thickness based on power-law model and the material properties are assumed to be temperature-dependent. Eringen's nonlocal elasticity theory is exploited to describe the size dependency of nanobeam. Using Hamilton's principle, the nonlocal equations of motion together with corresponding boundary conditions based on Timoshenko beam theory are obtained for the thermal buckling and vibration analysis of graded nanobeams including size effect. Moreover, in following a parametric study is accompanied to examine the effects of the several parameters such as nonlocal parameter, thermal effect, power law index and aspect ratio on the critical buckling temperatures and natural frequencies of the size-dependent FG nanobeams in detail. According to the numerical results, it is revealed that the proposed modeling can provide accurate frequency results of the FG nanobeams as compared some cases in the literature. Also, it is found that the small scale effects and nonlinear thermal loading have a significant effect on thermal stability and vibration characteristics of FG nanobeams.