• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1673-1680
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• 2003

It is essential to operate chemical lasers with supersonic ejector system as the laser output power goes up. In this research, ejector design parameter study was carried out for optimal ejector design through understanding the ejector characteristics and design requirements for chemical lasers operating. Designed ejector was 3D annular type with 2$^{nd}$ -throat geometry and pressurized air was used for primary flow. Ejector design was carried out with two steps, quasi-1D gas dynamics was used for first design and commercial code was used to verify the first design. In this study, to get the effect of ejector geometry on its performance, three cases of primary nozzle area ratio and 2$^{nd}$ -throat cross sectional area and two cases of 2$^{nd}$ -throat L/D ratio experiments were carried out. Primary and secondary pressures were measured to get the mass flow rate ratio, minimum secondary pressure, ejector starting pressure and unstarting pressure at every case. In the result, better performance than design level was shown and optimal ejector design method for chemical lasers was obtained.

• Journal of Korean Academy of Rural Health Nursing
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• v.15 no.1
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• pp.16-29
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• 2020

Purpose: The purpose of this study was to determine the effect on depression and self-esteem in elders taking part in the Magma healing program. Methods: This study was a single group pre-post quasi-experimental design. The participants were elders over 60 who had complained of depression more than once within the last 3 months, and who were living in the jurisdiction of a health clinic in the 3-area of Chungnam. Data from 14 elders who participated in the Magma healing program were analyzed using nonparametric paired t-test with SPSS 25.0. Results: The study results showed that the Magma healing program had statistically significant results in reducing depression (z=-2.91, p=.004) and improving self-esteem (z=-2.91, p=.004) in elders. Conclusion: The Magma healing program has been proven to be a very useful program to reduce depression in elders and promote self-esteem, thereby integrating their lives and leading to successful aging.

• Child Health Nursing Research
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• v.11 no.1
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• pp.63-71
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• 2005

Purpose: This study was done to examine the effects of a smoking prevention program on primary school students. Method: The design for this study was a nonequivalent quasi-experimental control group pretest-posttest. The smoking prevention program was provided to grade 5 and 6 students selected from two schools in Jecheon. The experimental group consisted of 72 students and the control group, 73 students. A smoking prevention program composed of smoking prevention education (once a week for 40 minutes over a period of 8 weeks) and supportive environment for smoking prevention was developed by modifying several smoking prevention programs. The research was conducted from May 15 to October 10, 2003. Result: 1) After completion of the smoking prevention program, the mean scores for knowledge about smoking, attitude to smoking, and intention toward non-smoking were not significantly different between the experimental group and the control group. Conclusions: To affectively achieve the aims of a smoking prevention program, the effectiveness of the program should not be measured over the short term only. Long-term tracking of students educated in the program, to identify the rate of those who later become smokers needs to be done.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2699-2708
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• 2020

Helical-coil steam generator (HCSG) technology is a major design candidate for small modular reactors due to its compactness and capability to produce superheated steam with high generation efficiency. In this paper, we investigate the feasibility of the passively autonomous power maneuvering by coupling the 3-D transient multi-physics of a soluble-boron-free (SBF) core with a time-dependent HCSG model. The predictor corrector quasi-static method was used to reduce the cost of the transient 3-D neutronic solution. In the numerical system simulations, the feedwater flow rate to the secondary of the HCSGs is adjusted to extract the demanded power from the primary loop. This varies the coolant temperature at the inlet of the SBF core, which governs the passively autonomous power maneuvering due to the strongly negative coolant reactivity feedback. Here, we simulate a 100-50-100 load-follow operation with a 5%/minute power ramping speed to investigate the feasibility of the passively autonomous load-follow in a 450 MW_th SBF PWR. In addition, the passively autonomous frequency control operation is investigated. The various system models are coupled, and they are solved by an in-house Fortran-95 code. The results of this work demonstrate constant steam temperature in the secondary side and limited variation of the primary coolant temperature. Meanwhile, the variations of the core axial shape index and the core power peaking are sufficiently small.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.423-429
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• 1997

A simplified method for determining the mode components of the strain energy release rate of free-edge delaminations in laminated composite is proposed. The interlaminar stresses are evaluated as an interface moment and interface shear forces that are obtained from the equilibrium equations at the interface between the adjacent layers. Deformation of an edge-delaminated laminate is calculated by using a generalized quasi-three dimensional classical laminated plate theory developed by the authors. The analysis provides closed-form expression for the three components of the strain energy release rate. Comparison of results with a finite element solution using the virtual crack closure technique shows good agreement. In the present study, laminated composite with stacking sequences of [30/-30/90]$_{s}$ were examined. The simple nature of the method makes it suitable for primary design analysis for the delaminations of laminated composite.e.

• Computers and Concrete
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• v.22 no.3
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• pp.269-278
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• 2018

In the recent decades, the application of composite materials, due to their desirable properties, has increased dramatically. In the present study, a quasi-encased trapezoidal section composite steel beam encased with concrete is thoroughly examined. Calculation of the load bearing capacity is carried out by finite element modeling of concrete and FRP beams with trapezoidal section under the effect of controlled displacement loading. The results are then validated comparing to the existing experimental results obtained from similar studies. Further on, the materials are changed to steel and concrete, and the section is de-signed in such a way that both concrete and steel reach a high percent-age of their load bearing capacity. In the last step, the parameters affecting the bending capacity and the behavior of the semi-confined composite beam are investigated. Results revealed that the beam diagonal web thickness plays the most effective role in load bearing capacity amongst other studied parameters. Furthermore, by analyzing the results on the effect of different parameters, an optimal model for primary beam section is presented, which exhibits a greater load bearing capacity compared to the initial design with the same amount of materials used for both sections.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.210-211
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• 2004

The effect of oscillating on the unsteady laminar flow past a circular cylinder is numerically investigated in the present study. Our study is to analyze the vortex formation behind a circular cylinder for different rotary oscillation conditions. And then we are study to portray the unsteady dynamics of wake flows. We decide lock-on region by observing the phase switching phenomena We classify the vortex formation patterns in the primary lock-on region The present study is to identify the quasi-periodic state around lock-on region. At the boundary between lock-on and non-lock-on the shedding frequency is bifurcated. After the bifurcation, one frequency follow the forcing frequency ($S_f$) and the other returns to the natural shedding frequency ($St_0$). In the quasi-periodic state, the variation of magnitudes and relevant phase changes of $C_L$ with forcing phase are examined.

• Communications for Statistical Applications and Methods
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• v.29 no.4
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• pp.421-439
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• 2022

Phase I dose-finding trials are essential in drug development. By finding the maximum tolerated dose (MTD) of a new drug or treatment, a Phase I trial establishes the recommended doses for later-phase testing. The primary toxicity endpoint of interest is often a binary variable, which describes an event of a patient who experiences dose-limiting toxicity. However, there is a growing interest in dose-finding studies regarding non-binary outcomes, defined by either the weighted sum of rates of various toxicity grades or a continuous outcome. Although several novel methods have been proposed in the literature, accessible software is still lacking to implement these methods. This study introduces a newly developed R package, UnifiedDoseFinding, which implements three phase I dose-finding methods with non-binary outcomes (Quasi- and Robust Quasi-CRM designs by Yuan et al. (2007) and Pan et al. (2014), gBOIN design by Mu et al. (2019), and by a method by Ivanova and Kim (2009)). For each of the methods, UnifiedDoseFinding provides corresponding functions that begin with next that determines the dose for the next cohort of patients, select, which selects the MTD defined by the non-binary toxicity endpoint when the trial is completed, and get oc, which obtains the operating characteristics. Three real examples are provided to help practitioners use these methods. The R package UnifiedDoseFinding, which is accessible in R CRAN, provides a user-friendly tool to facilitate the implementation of innovative dose-finding studies with nonbinary outcomes.

• Research in Community and Public Health Nursing
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• v.12 no.2
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• pp.344-360
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• 2001

A quasi-experimental study was conducted to investigate the effects of health promotion program on health of the clients with arthritis. In this study. the health promotion program consisted of self appointment and confirmation. discussion, health education. group counsel, and exercise. And the program focused on self - help group meeting. A total of 68 subjects was randomly assigned into either the control group(n = 24) or the intervention group(n =44). The results of the study analyzed using a SPSS win, were as follows: 1) In physical function of physical health. there was a significant improvement in flexibility of the shoulder joint(hold the hand upward and downward behind the back). sit and reach, extension of the knee joint in the intervention group, compared to the control group, while no difference in flexibility of the shoulder joint(raising the arm), flexion of the knee joint, and grip strength. There was a significant improvement in physical functional disability in the intervention group, compared to the control group, but no difference in fatigue and pain. 2) The health promotion program resulted in improvement in psychosocial health(e.g. increase of self-efficacy and decreases of social functional disability) in the intervention group, compared to the control group. It was concluded that the health promotion program(weekly session for 6 weeks) employed in this study was appropriate for the clients with arthritis in primary health care center and had a positive effect on health in general.

• Journal of International Academy of Physical Therapy Research
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• v.11 no.3
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• pp.2107-2112
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• 2020

Background: With the increasing elderly population, the need for gait analysis of these elderly individuals is also increasing. Most devices are costly and not portable; however, smartphones using built-in sensors capable of measuring motion and are easily available. Objectives: To examine the reliability and validity of knee joint angles of the elderly using smartphone measurements during walking. Design: Quasi-experimental research. Methods: Sixteen elderly people, aged 65+ and living in Daejeon and Chungbuk, South Korea, participated in the study. Electrogoniometers and smartphones were attached to the thigh and the side and front of the shank of each subject, respectively, using double-sided tape, an arm band, and an elastic band. Each subject completed two sets of at least seven gait cycles (14 steps). Results: Both the smartphones and electrogoniometers exhibited high agreement in terms of their primary and secondary measurements (ICC>.75). The agreement between the smartphones and electrogoniometers was also high in terms of both the primary and secondary measurements (ICC<.60). Conclusion: These results indicate that smartphones can be costly equipment cannot, even though they cannot completely replace existing clinical-grade devices. Their utility is emphasized herein for measuring knee joint angles of the elderly during walking.