• Journal of Power Electronics
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• v.18 no.3
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• pp.841-852
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• 2018

This paper presents a dual-algorithm search method (GWO-GSO) combining grey wolf optimization (GWO) and golden-section optimization (GSO) to realize maximum power point tracking (MPPT) for photovoltaic (PV) systems. First, a modified grey wolf optimization (MGWO) is activated for the global search. In conventional GWO, wolf leaders possess the same impact on decision-making. In this paper, the decision weights of wolf leaders are automatically adjusted with hunting progression, which is conducive to accelerating hunting. At the later stage, the algorithm is switched to GSO for the local search, which play a critical role in avoiding unnecessary search and reducing the tracking time. Additionally, a novel restart judgment based on the quasi-slope of the power-voltage curve is introduced to enhance the reliability of MPPT systems. Simulation and experiment results demonstrate that the proposed algorithm can track the global maximum power point (MPP) swiftly and reliably with higher accuracy under various conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.21-21
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• 2011

A series of Quasi-Elastic Neutron Scattering (QENS) experiments helps us to understand the single-particle (hydrogen atom) dynamics of a globular protein and its hydration water and strong coupling between them. We also performed Molecular Dynamics (MD) simulations on a realistic model of the hydrated hen-egg Lysozyme powder having two proteins in the periodic box. We found the existence of a Fragile-to-Strong dynamic Crossover (FSC) phenomenon in hydration water around a protein occurring at TL=$225{\pm}5K$ by analyzing Intermediate Scattering Function (ISF). On lowering of the temperature toward FSC, the structure of hydration water makes a transition from predominantly the High Density Liquid (HDL) form, a more fluid state, to predominantly the Low Density Liquid (LDL) form, a less fluid state, derived from the existence of a liquid?liquid critical point at an elevated pressure. We showed experimentally and confirmed theoretically that this sudden switch in the mobility of the hydration water around a protein triggers the dynamic transition (so-called glass transition) of the protein, at a temperature TD=220 K. Mean Square Displacement (MSD) is the important factor to show that the FSC is the key to the strong coupling between a protein and its hydration water by suggesting TL${\fallingdotseq}$TD. MD simulations with TIP4P force field for water were performed to understand hydration level dependency of the FSC temperature. We added water molecules to increase hydration level of the protein hydration water, from 0.30, 0.45, 0.60 and 1.00 (1.00 is the bulk water). These confirm the existence of the FSC and the hydration level dependence of the FSC temperature: FSC temperature is decreased upon increasing hydration level. We compared the hydration water around Lysozyme, B-DNA and RNA. Similarity among those suggests that the FSC and this coupling be universal for globular proteins, biopolymers.

• Journal of Korean Clinical Nursing Research
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• v.21 no.1
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• pp.11-20
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• 2015

Purpose: The purpose of this study was to identify effects of video-based information provision on anxiety and education satisfaction of patients with thyroid cancer who are undergoing radioiodine treatment. Methods: This study was a quasi-experimental study with a nonequivalent control group and nonsynchronized design. Data were collected from September 4 to December 31, 2013. Participants in this study were 60 patients (experimental group=30, control group=30) admitted after thyroidectomy. Video-based information developed by the authors was used with the experimental group at admission. The control group was provided with a booklet. State anxiety was measured using the Korean version of Spielberger's State-Trait Anxiety Inventory (STAI). Education satisfaction was measured with Visual Analogue Scale (VAS). Collected data were analyzed using SPSS windows 18.0 programs for Chi square test and t-test. Results: There was no significant difference in status anxiety between the two groups (t=1.05, p=.300). The experimental group had significantly higher level of education satisfaction than the control group (t=3.34, p=.001). Conclusion: Results indicate that providing video-based information is effective in increasing education satisfaction. Therefore, it is recommended that complementing and existing education with video-based information will contribute to enhanced nursing practice.

• Journal of Korean Academy of Nursing
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• v.35 no.7
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• pp.1295-1303
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• 2005

Purpose: This study was to determine the effects of abdominal breathing training using biofeedback on stress, immune response, and quality of life. Method: The study design was a nonequivalent control group pretest-posttest, quasi-experimental design. Twenty-five breast cancer patients who had completed adjuvant chemotherapy were enrolled. The experimental group(n=12) was provided with abdominal breathing training using biofeedback once a week for 4 weeks. State anxiety, cancer physical symptoms, serum cortisol, T cell subsets(T3, T4, T8), NK cell and quality of life were measured both before and after the intervention. Result: Though state anxiety, cancer physical symptoms, and serum cortisol were reduced after 4 weeks of abdominal breathing training using biofeedback, there was no statistical significance. It showed, however, improvement in quality of life (p=.02), and T3(p=.04). Conclusion: Abdominal breathing training using biofeedback improves quality of life in breast cancer patients after a mastectomy. However, the mechanism of this beneficial effect and stress response requires further investigation with special consideration in subject selection and frequency of measurement. Nurses should consider this strategy as a standard nursing intervention for people living with cancer.

• Perspectives in Nursing Science
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• v.8 no.1
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• pp.42-53
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• 2011

Purpose: This study was conducted to investigate the effects of aroma hand massage on anxiety and sleep in cancer patients during hospitalization. Methods: This study used a pre-post non-synchronized quasi-experimental design. Data were collected from 66 participating patients from July to December 2008. The participants were divided into an aroma massage group (n=25), a hand massage group (n=15), and a control group (n=26). The experimental group received aroma hand massage using 1% diluted lavender aroma oil once per day for 3 days. The massage was given by the researcher following the Korea Aromatherapy Health Professional Association massage protocol In contrast control group A received only a hand massage. The state anxiety, sleep condition, sleep satisfaction levels, and sleep duration were measured before and after the intervention trial. Results: The aroma hand massage group experienced in a significant decrease in their state anxiety (F=7.658 p=.001). Moreover, there was a significant increase in their sleep condition (F=18.047, p=.001), sleep satisfaction (F=30.016, p=.001) and sleep duration (F=23.019, p=.001) compared to the other groups according to one-way ANOVA and Scheffe's multiple comparison test. Also, noted was a significant increase in the sleep condition of the hand massage group as in the aroma hand massage group according to the Scheffe test. Conclusion: The study findings indicates that aroma hand massage decreases anxiety and increases the sleep condition, sleep satisfaction, and sleep duration of cancer patients.

• Steel and Composite Structures
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• v.46 no.4
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• pp.451-469
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• 2023

The use of precast hollow-core slabs (PCHCS) in civil construction has been increasing due to the speed of execution and reduction in the weight of flooring systems. However, in the literature there are no studies that present a finite element model (FEM) to predict the load-slip relationship behavior of pushout tests, considering headed stud shear connector and PCHCS placed at the upper flange of the downstand steel profile. Thus, the present paper aims to develop a FEM, which is based on tests to fill this gap. For this task, geometrical non-linear analyses are carried out in the ABAQUS software. The FEM is calibrated by sensitivity analyses, considering different types of analysis, the friction coefficient at the steel-concrete interface, as well as the constitutive model of the headed stud shear connector. Subsequently, a parametric study is performed to assess the influence of the number of connector lines, type of filling and height of the PCHCS. The results are compared with analytical models that predict the headed stud resistance. In total, 158 finite element models are processed. It was concluded that the dynamic implicit analysis (quasi-static) showed better convergence of the equilibrium trajectory when compared to the static analysis, such as arc-length method. The friction coefficient value of 0.5 was indicated to predict the load-slip relationship behavior of all models investigated. The headed stud shear connector rupture was verified for the constitutive model capable of representing the fracture in the stress-strain relationship. Regarding the number of connector lines, there was an average increase of 108% in the resistance of the structure for models with two lines of connectors compared to the use of only one. The type of filling of the hollow core slab that presented the best results was the partial filling. Finally, the greater the height of the PCHCS, the greater the resistance of the headed stud.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.5
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• pp.311-317
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• 2023

An autofilter is a device that removes impurities contained in heavy fuel oil used in diesel engines of ships or power plants, and also automatically removes impurities accumulated in the filter through a reverse washing function. The reducer-integrated motor serves to rotate the filter at low speed to enable reverse automatic cleaning in the autofilter device. To achieve a low speed of 0.65 to 0.75 rpm in a reducer-integrated motor, a small motor that can operate at 97rpm at a rated voltage of 110 V and 112.5 rpm at 220 V is required. Additionally, a large gear ratio of 1/150 is required. To ensure the durability and reliability of these reducers, the strength of the gear must be evaluated at the design stage. In general, there is a limit to evaluating the stress and strain state according to the vibration characteristics acting on each gear in the driving state of the reducer through quasi-static analysis. Therefore, in this study, the operation characteristics of the auto filter's reducer-integrated motor were first analyzed using the rigid body dynamics analysis method. Then, this rigid body dynamics analysis model was extended to a flexible multibody dynamics analysis model to analyze the stress and strain states acting on each gear and evaluate the design feasibility of the gear.

• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.418-426
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• 2022

Unlike OSR(observation space representation), the SSR(state space representation) augmentation system is suitable for a one-way broadcasting service because it provides the same corrections to all users in the service area. Due to this advantage, several GNSS(global navigation system) systems such as Galileo, BDS(beidou navigation satellite system), QZSS(quasi zenith satellite system) are establishing PPP (precise point positioning)/PPP-RTK precision positioning services based on SSR messages. Therefore, in this paper, we try to understand the trends of satellite-based PPP/PPP-RTK correction services by analyzing the system configurations, characteristics, and precise positioning performance of satellite-based SSR correction broadcasting services.

• The Journal of the Acoustical Society of Korea
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• v.25 no.8
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• pp.356-361
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• 2006

We present the performance of differential space-time block decoders. which does not require the channel state information. We suggest the structure of the multiple blocks differential space time decoders. which does not require the channel state information, and analyze the Performances. In quasi-static flat fading channels. the Performance of multiple blocks differential detection (MD-STC) outperforms that of 2 blocks(D-STC) by 1.5dB. But in the time-selective fading channels due to Doppler frequency $(f_d)$, the performance of MD-STC degrades as the vehicular speed is greater than 200km/hr in 802.16e systems, where the data transmission rate is 144kbps.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.49.2-49.2
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• 2015

IntraCluster Medium (ICM) located at the galaxy cluster is in the state of very hot, tenuous, magnetized, and highly ionized X-ray emitting plasmas. High temperature and low density make ICM very viscous and conductive. In addition to the high conductivity, fluctuating random plasma motions in ICM, occurring at all evolution stages, generate and amplify the magnetic fields in such viscous ionized gas. The amplified magnetic fields in reverse drive and constrain the plasma motions beyond the viscous scale through the magnetic tension. Moreover, without the influence of resistivity viscous damping effect gets balanced only with the magnetic tension in the extended viscous scale leading to peculiar ICM energy spectra. This overall collisionless magnetohydrodynamic (MHD) turbulence in ICM was simulated using a hyper diffusivity method. The results show the plasma motions and frozen magnetic fields have power law of $E_V^k{\sim}k^{-3}$, $E_M^k{\sim}k^{-1}$. To explain these abnormal power spectra we set up two simultaneous differential equations for the kinetic and magnetic energy using an Eddy Damped Quasi Normal Markovianized (EDQNM) approximation. The solutions and dimensions of leading terms in the coupled equations derive the power spectra and tell us how the spectra are formed. We also derived the same results with a more intuitive balance relation and stationary energy transport rate.