• The KSFM Journal of Fluid Machinery
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• v.15 no.4
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• pp.27-32
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• 2012

Gas turbines for an aircraft have the start and restart capabilities within their flight envelop. It is an important item for engine qualification and substantiated with the test. Experimental investigations were carried out to find the relation between the corrected torque and the corrected rotating speed of an air turbine starter in this study. A dedicated air supply system for the air turbine starter and a special device to measure the torque and the rotating speed of the air turbine starter were developed and installed at the altitude engine test facility in Korea Aerospace Research Institute. Experimental results show that the relations between the corrected torque and the corrected rotating speed of the air turbine starter are linear and the inlet temperature and pressure conditions for the air turbine starter were found out to provide minimum required torque for the engine qualification test at various altitude. The start and restart tests for the currently developing engine were successfully performed using this experimental results.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1926-1938
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• 2020

We validated the performance of RELAP MOD3.3 code regarding the hybrid SIT with available experimental data. The concept of the hybrid SIT is to connect the pressurizer to SIT to utilize the water inside SIT in the case of SBO or SB-LOCA combined with TLOFW. We investigated how well RELAP5 code predicts the physical phenomena in terms of the equilibrium time, stratification, condensation against Separate Effect Test (SET) data. We also conducted the validation of RELAP5 code against Integrated Effect Test (IET) experimental data produced by the ATLAS facility. We followed conventional approach for code validation of IET data, which are pre-test and post-test calculation. RELAP5 code shows substantial difference with changing number of nodes. The increase of the number of nodes tends to reduce the condensation rate at the interface between liquid and vapor inside the hybrid SIT. The environmental heat loss also contributes to the large discrepancy between the simulation results of RELAP5 and the experimental data.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.18 no.4
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• pp.488-496
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• 2011

Purpose: To determine the type and degree of effect that a hot footbath has on sleep quality and fatigue level in older Korean adults. Methods: A non-equivalent control group quasi-experimental design was used. Fifty participants from a long-term care facility in Kwangju, South Korea, were randomly selected and assigned to two groups: experimental group (27 participants) and control group (23 participants). The participants in the experimental group received hot footbaths in a temperature-controlled water tub of $42^{\circ}C$. They soaked their feet up to 20cm above the ankles for 30 minutes before going to bed for 3 nights. Actigraphy was used to measure their sleep patterns. The data were analyzed using the SAS program. Results: After the intervention, the total sleep satisfaction rate of the participants increased, while sleep latency and fatigue decreased significantly in the experimental group compared to the control group. Conclusion: The study results suggest that hot footbaths are beneficial for older Korean adults in enhancing sleep quality as well as reducing fatigue. Therefore, hot footbaths are recommended as a nursing intervention to improve sleep quality and to reduce fatigue in older Korean adults.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.89-94
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• 2014

The 4th generation SFR is being designed with a milestone of construction by 2028. It is important to understand the subchannel flow characteristics in fuel assembly through the experimental investigations and to estimate the calculation uncertainties for insuring the confidence of the design code calculation results. The friction coefficient and the mixing coefficient are selected as primary parameters. The two parameters are related to the flow distribution and diffusion. To identify the flow distribution, an iso-kinetic method was developed based on the previous study. For the mixing parameters, a wire mesh system and a laser induced fluorescence methods were developed in parallel. The measuring systems were adopted on 37 rod bundle test geometry, which was developed based on the Euler number scaling. A scaling method for a design of experimental facility and the experimental identification techniques for the flow distribution and mixing parameters were developed based on the measurement requirement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.306-313
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• 2006

Automated material handling system is being used as a method to reduce manufacturing cost in the semiconductor and flat panel displays (FPDs) manufacturing process. Those are considering switch-over from the traditional cassette system to single-substrate transfer system to reduce raw materials of stocks in the processing line. In the present study, the wafer transportation speed has been evaluated by numerical and experimental method for three propulsion nozzle array (face, front, rear) in an air levitation system. Test facility for 300 mm wafer was equipped with two control tracks and a transfer track of 1,500mm length. The diameter of propulsion nozzle is 0.8mm and air velocity of wafer propulsion is $50\sim150m/s$. We found that the experimental results of the wafer transportation speed were well agreed with the numerical ones. Namely, the predicted values of the maximum wafer transportation speed are higher than those values of experimental data by 16% and the numerical result of the mean wafer transportation speed is higher than the experimental result within 20%.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.308-311
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• 2008

As a severe accident mitigation strategy in a nuclear power plant, ERVC(External Reactor Vessel Cooling) has been proposed. Under ERVC conditions, where a molten corium is relocated in a reactor vessel lower head, a natural circulation two-phase flow is driven in the annular gap between the reactor vessel wall and its insulation. This flow should be sufficient to remove the decay heat of the molten corium and maintain the integrity of the reactor vessel. Preliminary experimental study was performed to estimate the natural circulation two-phase flow. The experimental facility which is one dimensional, the half height, and the 1/238 channel area of APR1400, was prepared and the experiments were carried out to estimate the natural circulation two-phase flow with varying the parameters of the coolant inlet area, the heat rate, and the coolant inlet subcooling. In results, the periodic circulation flow was observed and the characteristics were varied from the experimental parameters. The frequency of the natural circulation flow rate increased as the wall heat flux increased.

• Journal of the Korean Society of Physical Medicine
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• v.13 no.4
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• pp.59-65
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• 2018

PURPOSE: The purpose of the present study is to investigate the changes in the cognitive function of elderly dementia patients residing in a residential care facility, following six weeks of brain-computer interface (BCI)-based cognitive training and to determine whether BCI-based cognitive training effectively improves their cognitive functions. METHODS: Thirty subjects diagnosed with dementia were randomly assigned to either the experimental or control group. Pre- and post-test cognitive function assessments were conducted using the mini mental state examination-Korean (MMSE-K) and Korean-dementia rating scale (K-DRS). The experimental group received BCI-based cognitive training, which consisted of games such as flying a ball and exploding a bomb, while the control group participated in music listening activities and National Health Gymnastics. Both groups engaged in a total of 18 sessions (3 times per week for 6 weeks, for 40 minutes per session). RESULTS: After 6 weeks of intervention, the experimental group had significantly increased MMSE-K scores ($19.53{\pm}1.30$ to $22.20{\pm}1.15$; p<.0011) and total K-DRS scores ($87.20{\pm}4.16$ to $99.33{\pm}1.15$; p<.0011). In addition, the experimental group showed greater cognitive improvements than the control group. CONCLUSION: The results of this study suggest that BCI-based cognitive training is a positive intervention tool for improving the cognitive function of dementia patients.

• Wind and Structures
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• v.28 no.5
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• pp.271-284
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• 2019

This paper describes the application of a novel virtual prototyping methodology to wind turbine blade design. Numeric modelling data and experimental data about turbine blade geometry and structural/dynamical behaviour are combined to obtain an affordable digital twin model useful in reducing the undesirable uncertainties during the entire turbine lifecycle. Moreover, this model can be used to track and predict blade structural changes, due for example to structural damage, and to assess its remaining life. A new interactive and recursive process is proposed. It includes CAD geometry generation and finite element analyses, combined with experimental data gathered from the structural testing of a new generation wind turbine blade. The goal of the research is to show how the unique features of a complex wind turbine blade are considered in the virtual model updating process, fully exploiting the computational capabilities available to the designer in modern engineering. A composite Sandia National Laboratories Blade System Design Study (BSDS) turbine blade is used to exemplify the proposed process. Static, modal and fatigue experimental testing are conducted at Clarkson University Blade Test Facility. A digital model was created and updated to conform to all the information available from experimental testing. When an updated virtual digital model is available the performance of the blade during operation can be assessed with higher confidence.

• Journal of muscle and joint health
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• v.30 no.3
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• pp.230-241
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• 2023

Purpose: This study aimed to verify the effects of a swallowing training program on swallowing function and depression for nursing home residents with dysphagia after stroke. Methods: This is a quasi-experimental study with non-equivalent control group pre-post test design. The program (oro-facial muscle strengthening exercises, swallowing exercises, expiratory muscle strengthening exercises, and brain stimulation exercises) applied to the experimental group three times per week for eight weeks, 40-45 minutes for each intervention. The final data from 42 people (21 experimental and 21 control) were analyzed by SPSS/WIN 25.0 using descriptive statistics. 𝜒² test, t-test, Wilcoxon rank sum test, and Friedman test. Results: The experimental group was significantly improved than control group in oro-facial muscle strength, swallowing symptoms (Z=-2.22, p=.026), and oral intake function level (Z=-2.00, p=.046). However, there was no significant difference between two groups in depression. Conclusion: This study is meaningful in that it reorganized and mediated a swallowing training program as a safe, non-invasive exercise that nurses can implement in a nursing facility with limited medical personnel and it could be easily followed by older adults.

• Journal of the Korea Concrete Institute
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• v.29 no.2
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• pp.169-177
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• 2017

Rather than causing damage from heat, blast, and radiation of a regular nuclear weapon, recently, it is predicted that North Korea has been inventing high altitude electromagnetic pulse (HEMP) missile in order to incapacitate electronic equipment. HEMP shielding facility is used for military purpose today. Despite the electromagnetic shielding effects from high quality compression plates, problems may include such as the possibility of electromagnetic influx resulting in the welding of the compression plates, and difficulties and high cost of construction. Therefore, in this study, a high electrical conducting material was added to the concrete experimental subject to ensure the shielding effect through electromagnetic waves to for the concrete structure, instead of building a shielding facility separately for the structure. Also, among the experimental subjects, 100 ${\mu}m$ of Iron-Aluminum alloy metal spraying coat was applied to two types with the highest shielding effect, and to two types with the lowest shielding effect. The result of the experiment indicates that experimental subjects added with a high electrical conductivity material did not meet the minimum shielding criteria of MIL-STD-118-125-1 standard, but all the experimental material applied to the metal spraying coating satisfied the minimum shielding criteria. In conclusion, it is considered that 100 µm of Iron-Aluminum alloy metal spraying coat contains high efficiency in the HEMP shielding.