• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.6
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• pp.1453-1462
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• 1996

A numerical simulation is carried out on the directiveity synthesis of ultrasonic transducers by point source array. Directive method with combined LMS(Least-Mean-Square) method is practiced by means of a iterative method to realize the desired directivity. The directiviey of quasi-ideal beam with a beam width and a directive arbitrary specified was chosen. On the numerical resut, Proposed algorithm shows higher speed of clculating simulation than that of LMS method, and make adaptive control, which enables the desired directivity. Numerical simulations are carried out by PC(CPU:80486 DX2, RAM 16Mbyte).

• Journal of Magnetics
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• v.16 no.4
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• pp.408-412
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• 2011

We investigated theoretically the magnetic field dependence of the quantum optical transition of qusi 2-Dimensional Landau splitting system, in GaN and ZnO. We apply the Quantum Transport theory (QTR) to the system in the confinement of electrons by square well confinement potential. We use the projected Liouville equation method with Equilibrium Average Projection Scheme (EAPS). Through the analysis of this work, we found the increasing properties of the optical Quantum Transition Line Shapes(QTLSs) which show the absorption power and the Quantum Transition Line Widths(QTLWs) with the magnetic-field in GaN and ZnO. We also found that QTLW, ${\gamma}(B)_{total}$ of GaN < ${\gamma}(B)_{total}$ of ZnO in the magnetic field region B < 25 Tesla.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.5
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• pp.537-551
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• 2017

In this paper, a two-phase flow solver $HiFoam^{(R)}$ has been developed based on the $OpenFOAM^{(R)}$ to predict resistance of a ship in calm water. The VOF method of $OpenFOAM^{(R)}$ was reviewed and a simple flux limiter was introduced to enhance the robustness of the solver. The procedure for predicting ship motion was modified by introducing Quasi-Steady Fluid-Body Interaction (QS-FBI) with least square regression to improve the efficiency. Other minor factors were considered as well in terms of the efficiency and robustness. The HiFoam was applied to KCS and JBC simulations to validate its efficiency and accuracy by comparing the results to experimental data and STAR-CCM+. The $HiFoam^{(R)}$ was also applied to various ships and it showed good agreements to the experimental data.

• Journal of Korean Biological Nursing Science
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• v.18 no.3
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• pp.185-191
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• 2016

Purpose: The purpose of this study is to understand the effect of taking calcium/vitamin D supplements and performing Taekkyeon exercises on the frailty of the elderly targeting a vulnerable senior social group. Methods: A total of 124 people aged 65 and older consisting of 60 persons in the experimental group, and 64 persons in the control group participated in this study, and this study is a non-equivalent control group pre/post-test design quasi-experimental study. This study analyzed the homogeneity between the experimental group and the control group using a chi-square test and t-test while analyzing the difference in the degree of frailty and bone density with the practice of Taekkyeon and a calcium agent using t-test and GEE. Results: The study results showed that the frailty and bone density of the experimental group significantly improved. Conclusion: Through this study, it was confirmed that calcium/vitamin D intake and Taekkyeon exercises were an effective intervention which strengthened the elderly's physical condition.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.16 no.3
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• pp.300-306
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• 2009

Purpose: This study was done to investigate differences between lavender abdominal massage and inhalation on dysmenorrhea, menstrual pain, anxiety, and depression. Methods: This study used a non equivalent quasi-experimental design. Lavender essential oil and almond oil were used in massage and a lavender necklace and artificial perfume necklace in inhalation for female college students. Frequencies, percentages, Chi-square, Fisher's exact test and t-test with the SPSS/WIN 12.0 program were used to analyze the data. Results: Dysmenorrhea was significantly higher inhalation for placebo treatment compared to lavender inhalation (p< .001). There was not significant difference between lavender abdominal massage and inhalation. Conclusion: Lavender abdominal massage and inhalation could be effective methods to reduce dysmenorrhea. However, before lavender abdominal massage and inhalation can be considered as intervention, it is more needed to study of menstrual pain, anxiety and depression.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2725-2736
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• 1998

In this paper. we present a new pitch determination method for speech analysis. namely VFF(Variable Forgetting Factor) based. by using the WRLS-VFF-VT(Weighted Recursive Least Square-Variable Forgetting Factor-Variable Threshold) algorithm. A proposed method uses VFF to identify the glottal closure points which correspond to the instants of the main excitation pulses for voiced speech. The modified EGG

• Women's Health Nursing
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• v.27 no.4
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• pp.388-404
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• 2021

Purpose: The purpose of this study was to examine the effects of team-based learning (TBL) on nursing students' communication ability, problem-solving ability, self-directed learning, and nursing knowledge related to high-risk pregnancy nursing. Methods: This quasi-experimental study used a nonequivalent control group pretest-posttest design. The participants were 91 nursing students allocated to an experimental group (n=45) and a control group (n=46). The experimental group received TBL lectures three times over the course of 3 weeks (100 minutes weekly) and the control group received instructor-centered lectures three times over the course of 3 weeks (100 minutes weekly). Data were collected by questionnaires from September to November, 2019. Data were analyzed using the chi-square test, paired t-test, and independent t-test. Results: After the intervention, the mean scores of problem-solving ability (t=-2.59, p=.011), self-directed learning (t=4.30, p<.001), and nursing knowledge (t=3.18, p=.002) were significantly higher in the experimental group than in the control group. No significant difference in communication ability was found between the experimental and control group (t=1.38, p=.171) Conclusion: The TBL program was effective for improving nursing students' problem-solving ability, self-directed learning, and nursing knowledge. Thus, TBL can be considered an effective teaching and learning method that can improve the learning outcomes of high-risk pregnancy nursing in women's health nursing classes. The findings suggest that TBL will be helpful for future nursing students to develop the nursing expertise necessary for providing nursing care to high-risk pregnant women.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2703-2714
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• 2002

In this work, energy absorption characteristics and optimal welding space of spot-welded square hat type tube are investigated via quasi-static crush experiments and finite element (FE) analyses. A FE model reflecting the crush characteristics is established based on the experimentally observed crush mechanisms of specimens with welding spaces (20, 30 & 45 mm) and (25,40 & 55 mm) respectively for two specimen widths (60, 75 mm). The established FE model is then applied to other crush models of widths (50, 60 & 75 mm) with various welding spaces (20, 25, 30, 40, 45, 55, 75, 150, 300 mm) respectively. We examine the energy absorption characteristics with respect to the welding space for each specimen width. The outcome suggests an optimal spot welding space of square hat type thin-walled tube. Energy absorption is also presented in terms of yield strength of base metal, specimen thickness, width, and mean crushing force of spot-welded square hat type thin-walled tube.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.33-38
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• 2008

Most structures of vehicle are composed of many substructures connected to one another by various types of mechanical joints. In vehicle engineering, it is important to study these jointed structures under random frequency vibration for the evaluations of fatigue life and stress concentration exactly. It is rarely obtained the accurate load history of specified positions in a jointed structure because of the errors such as modeling, measurement, and etc. In the beginning of design, exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the hybrid method of practical dynamic load determination is developed by the combination of the principal stresses from F. E. Analysis and test of a jointed structure. Least square pseudo inverse matrix is adopted to obtain an inverse matrix of analyzed stresses matrix. The error minimization method utilizes the inaccurate measured error and the shifting error that the whole data is stiffed over real data. The least square criterion is adopted to avoid these errors. Finally, to verify the proposed system, a heavy-duty bus is analyzed. This measurement and prediction technology can be extended to the different jointed structures.

• Journal of Korean Academy of Nursing
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• v.39 no.4
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• pp.528-538
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• 2009

Purpose: This study was done to develop and test a palliative care program based on home care nursing. Methods: A quasi-experimental design was employed. Changes in the variables were evaluated to test effects of the developed program. Participants were patients with terminal cancer and their families receiving home care nursing from six hospitals (experimental group: 24 and control group: 22). Data collection was conducted from February to October, 2006. Chi-square test, Fisher's exact test, t-test, Mann-Whitney U test and repeated measures ANOVA were used to analyse the data. Results: Hypothesis 1, the experimental group receiving this program will experience less pain (severe, average, weak pain) than the control group, was supported. Hypothesis 2, the experimental group will have less symptom experience than the control group, was supported. Hypothesis 3, the experimental group will have higher QOL than the control group, was supported and the last hypothesis 4, family burden in the experimental group will be less than the control group, was supported. Conclusion: The home care nursing based palliative program developed in this study was found to be an effective program to reduce patient pain and symptom experience, to improve patient QOL and to decrease family burden.