• Journal of Korea Foundry Society
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• v.17 no.4
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• pp.385-392
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• 1997

The main objective of this study is to investigate the microstructure and tensile strength of $SiC_p$/Al alloy composites fabricated by die casting method. Die casting was performed using the preheated mold at the pouring temperature range of $620{\sim}750^{\circ}C$ under the pressure of $1,039 kgf/cm^2$. The low speed and a following high injection speed were 0.4 and 2.1 m/s, respectively. The microstructure of $SiC_p$/Al alloy composites fabricated by die casting method was found to be finer than that of composites fabricated by gravity casting. Also, SiC particulates were homogeneously distributed in refined Al matrix due to rapid solidification. The tensile strength of $SiC_p$/Al alloy composites fabricated by die casting method was found to be varied with cast temperature. The maximun tensile strength of $SiC_p$(10 vol.% and 20 vol.%)/Al alloy composites showed 380 MPa at the cast temperature of $750^{\circ}C$ and 363 MPa at the cast temperature of $700^{\circ}C$, respectively.

• Journal of Korean Academy of Nursing
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• v.49 no.1
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• pp.92-103
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• 2019

Purpose: This study aimed to compare the effects of simulation integrated with problem based learning (S-PBL) according to the sequences of problem-based learning (PBL) and high fidelity simulation training (HFS) on knowledge, clinical performance, clinical judgment, self-confidence, and satisfaction in fourth-grade nursing students. Methods: In this randomized crossover design study, four S-PBLs on medical-surgical nursing were applied alternatively to two randomly-assigned groups of 26 senior nursing students for 8 weeks. The collected data were analyzed using an independent t-test. Results: The method of administering PBL prior to HFS led to significantly higher scores on knowledge (t=2.28, p=.025) as compared to the method of administering HFS prior to PBL. However, the latter method led to significantly higher scores on clinical performance (t=-6.49, p<.001) and clinical judgment (t=-4.71, p<.001) as compared to the method of administering PBL prior to HFS. There were no differences in the effect of the two methods on self-confidence (t=1.53, p=.128) and satisfaction (t=1.28, p=.202). Conclusion: The integration sequences of S-PBL was associated with different learning outcomes. Therefore, when implementing S-PBL, it is necessary to consider the educational goal to executes an appropriate sequence of integration.

• Journal of Korean Academy of Nursing
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• v.34 no.7
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• pp.1184-1193
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• 2004

Purpose: The purpose of this study was to explore the relationship of uncertainty, hope and quality of life in patients with breast cancer. Method: The subjects of the study were 113 breast cancer patients treated at 3 university hospitals in Daegu and Busan from June 1 to September 30, 2003. Uncertainty was measured by the Mishel Uncertainty in Il1ness Scale (MUIS), Hope was measured by Nowotny's Hope Scale, and quality of life by Ro's Korean Quality of Life(QOL). Data was analyzed with the SPSS program by t-test, ANOVA, Spearman's rank correlation and Multiple Regression Analysis. Result: The scores of uncertainty were negatively correlated with hope and QOL(all p's<0.05). Uncertainty revealed that there was a negative correlation among subitems of hope such as confidence, relationship with others, possibility of future, and inner motivation(r=-.333, p=.000; r=-.230, p=.015; r=-.260, p=.006; r=-.291, p=.003). Uncertainty also showed a negative correlation among subitems of QOL such as emotional status, self esteem, and relationship with family(r=-.29, p=.004; r=-.326, p=.000; r=-.197, p=.044), whereas hope revealed a positive correlation among subitems of QOL such as emotional status, self esteem, relationship with neighbor, and relationship with family(r=.243, p=.011; r=.487, p=.000; r=.29, p=.001; r=.29, p=.001). The score of uncertainty was low in graduate school students and subjects using problem solving as a coping method. However, the score of hope was high in college students and subjects using a problem solving method, and the score of QOL was high in professionals. Conclusion: Based on the study results, breast cancer patients experienced living with uncertainty and maintaining hope. Thus the study's findings can be useful in directing a comprehensive nursing care plan to improve QOL of breast cancer patients.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.656-666
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• 2022

The purpose of this study is to evaluate the effect on the grit, learning reality, and learning satisfaction for nursing students using the flipped learning teaching method. We developed a flipped learning educational program using ADDIE model for nursing students and evaluated the program effect. As a result of this study, the grit (t=-3.07, p=.003), the learning presence (t=-4.87, p<.001) and the learning satisfaction (t=-5.18, p<.001) significantly increased after flip learning method application. The Grit shown to have a significant positive correlation with learning presence (r = .47, p<.001), and learning satisfaction (r = .26, p<.005). The learning presence shown to have a significant positive correlation with learning satisfaction (r = .548, p<.001). The flipped learning teaching method may improve the grit, learning reality, and learning satisfaction. Various efforts will be needed to lay the foundation for flipped learning teaching methods in the field of nursing education in the future.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.112-117
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• 2005

Two modified versions of subspace iteration method using accelerated starting vectors are proposed to efficiently calculate free vibration modes of structures. Proposed methods employ accelerated Lanczos vectors as starting iteration vectors in order to accelerate the convergence of the subspace iteration method. Proposed methods are divided into two forms according to the number of starting vectors. The first method composes 2p starting vectors when the number of required modes is p and the second method uses 1.5p starting vectors. To investigate the efficiency of proposed methods, two numerical examples are presented.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.2
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• pp.82-89
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• 1985

A new non-inferior solution is obtained by investigating method of weight p- norm to explain the conception of MCO (multiple criterion optimization) problem. And then the optimum non-inferior solution is obtained by the weight minimization method applied to objective function of MOSFET NAND rATEAlso this weight minimization method using weight P- norm methods can be applied to non-convex objective function. The result of this minimization method shows the efficiency in comparison with that of Lightner.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.619-627
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• 2008

In this study, through dissipation test of DMT predicted Horizontal Coefficient of Consolidation at marine clay. CPTu Dissipation test, laboratory consolidation test compared with $C_v$, through it examined application. The result, DMT calculated horizontal coefficient of consolidation by $P_2$-Log(t) method of DMT-A method and C-$\surd$t(min) method. This horizontal coefficient of consolidation calculated larger than $P_2$-Log(t) method. $P_2$-Log(t) method of DMT, Torstensson of CPTu and Houlsby & Teh(1991) appeared similar to tend. This approximate value is possible application in marine clay. It'll need to study continuously through collection of data.

• Journal of Mushroom
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• v.2 no.1
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• pp.42-43
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• 2004

Labor required for managing and harvesting the oyster mushroom bed was evaluated. Although vinyl mulching cultivation method needs more hours for spawning, it saves more than 50% of labor for harvesting and managing of the mushroom bed. Harvesting hour of 1st-3rd flush in vinyl mulching method was 48~50% for Plerutus ostreatus and 36~41% for P. sajor-caju. Labor for bed management after harvesting in vinyl mulching method was also 38~50% for P. ostreatus compared to conventional method, and 20~35% for P. sajor-caju. Vinyl mulching is believed to be a very efficient method for saving labor in oyster mushroom cultivation.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.1
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• pp.29-36
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• 2020

In this study, a variable step algorithm is proposed on the basis of the perturb and observe method. The proposed algorithm can follow the maximum power point (MPP) quickly when solar irradiance changes rapidly. The proposed technique uses the voltage change characteristic at the MPP when the environment changes because of insolation or temperature. The MPP is tracked through the voltage control using a variable step method. This method determines the sudden change of solar irradiance by setting the threshold value and operates in fast tracking mode to track the MPP rapidly. When the operation point reaches the MPP, the mode switches to the variable step mode to minimize the steady state error. In addition, the output disturbance is decreased through the optimization of the control method design. The performance of the proposed MPPT algorithm is verified through simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.159-166
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• 2021

This study compares the maximum power point tracking (MPPT) control methods of a thermoelectric generator on vehicles. The researchers conduct comparisons on five different MPPT methods, including a fractional open circuit voltage method, a perturbation and observation (P&O) method, an incremental conductance method, a linear extrapolation-based MPPT (LEMPPT) method, and a LEMPPT/P&O hybrid method. These five MPPT methods are theoretically analyzed in detail, and the comparisons are conducted through MATLAB/Simulink simulation results. The comparison outcomes reveal that linear MPPT methods, including LEMPPT and LEMPPT/P&O hybrid methods, are more suitable for a thermoelectric generator on vehicles than the other MPPT methods examined in this work.