• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1878-1886
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• 2021

For industrial package (IP)-type transport containers for radioactive materials, a free drop test should be conducted under regulatory conditions. Owing to various uncertainties observed during the drop test, errors in drop angles inevitably occur. In IP-type metal transport containers in which the container directly impacts onto a rigid target without any shock absorbing materials, the error in the drop angle due to a slight misalignment makes a significant difference from the ideal drop. In particular, in a vertical drop, the error in the drop angle causes a strong secondary impact. In this paper, a numerical method is proposed to estimate the error in the drop angle occurring during the test. To determine this error, an optimization method accompanying a computational drop analysis is proposed, and a surrogate model is introduced to ensure calculation efficiency. Effectiveness of the proposed method is validated by performing the verification and comparison between the test and the analysis applied with the drop angle error.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.940-947
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• 2011

Load capacity varies according to a day of the week in traction power supply system, because time schedule in railway is changed as demand for passengers and freights. Therefore, Voltage drop also varies as load capacity. In Korea railway, Voltage collected from catenary in train is decreased, as load supplied traction power supply system is increased. Therefore, investigation about voltage drop should be performed, before development of countermeasure against voltage drop. The investigation can be performed by simulation or field test. Naturally, field test is more precise than simulation. In addition, field test should be carried out at peak load. This paper presents test and analysis about voltage drop in railway. The test is performed in both a day of the week and weekend. The analysis is figured out comparison load capacity between two days and voltage drop across terminal.

• YAKHAK HOEJI
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• v.57 no.2
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• pp.139-149
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• 2013

Glaucoma is a potentially blinding chronic disease requiring life-long commitment to medical therapy. Failure to adhere to anti-glaucoma treatment may lead to disease progression and visual loss. This study surveyed the adherence to glaucoma eye drop and eye drop instillation technique of glaucoma patients and analyzed the improvement of the adherence and installation technique after patient education for eye drop instillation instructions. Collected responses were statistically analyzed using Kruskal-Wallis test, Mann-Whitney test, Chi-square test, Fisher's exact test, Spearman's correlation coefficient, or one sample proportion test. The survey after patient education for proper eye drop instillation revealed that, even if the patients experienced the adverse effect of their eyes getting dry, they used the eye drop more regularly. They were better at instillation techniques like putting the eye drop inside the eye, and also avoiding applying too much medication or touching their eye with the eye drop bottle. Also, when the patients were divided into groups based on etiologic division, there was difference among groups regarding which category they answered has improved. The result showed improvement in adherence to glaucoma eye drop and eye drop instillation technique after patient education, implicating that patient education is an important aspect of eye care for glaucoma patient and helps them participate in the proper management.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.2210-2211
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• 2011

Load capacity varies according to a day of the week in traction power supply system, because time schedule in railway is changed as demand for passengers and freights. Therefore, Voltage drop also varies as load capacity. In Korea railway, Voltage collected from catenary in train is decreased, as load supplied traction power supply system is increased. Therefore, investigation about voltage drop should be performed, before development of countermeasure against voltage drop. The investigation can be performed by simulation or field test. Naturally, field test is more precise than simulation. In addition, field test should be carried out at peak load. This paper presents test and analysis about voltage drop in railway. The test is performed in both a day of the week and weekend. The analysis is figured out comparison load capacity between two days and voltage drop across terminal.

• Journal of Aerospace System Engineering
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• v.18 no.3
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• pp.56-64
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• 2024

In this study, a drop impact tester was developed to comprehensively conduct basic testing and academic research on the drop impact characteristics of aerospace structures. A drop tester enables accurate assessment of the dynamic stresses and deformations that occur when an aircraft collides with the ground, thereby enabling the verification of important design factors, such as safety and mechanical strength. The drop tester consists of an electromagnet to attach and drop the test object, a crane to adjust the drop height of the test object, and a drop support structure for vertical drops. Numerical analysis of the drop test object for the test was performed, and basic tests were performed using the drop impact tester. Through the analysis and test results, the structural shape of the landing gear was analyzed, and the behavior of each part was evaluated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.250-254
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• 2011

Main role of landing gear is to absorb the energy which is generated by aircraft lanidng and ground maneuvering. Generally, in order to absorb the impact energy during landing, oleo-pneumatic type shock absorber is used for aircraft landing gear. Oleo-pneumatic type shock absorber has a good energy absorbing efficiency and is light in weight because its structure is relatively simple. For the landing gear development, it is necessary to conduct drop test in order to verify shock absorbing performance. In the drop test, first, gas spring curve verification tests are conducted. Then, limit and reserve energy absorption drop tests are performed based on the STANAG 4671. The drop tests results with performance analysis results are presented.

• PNF and Movement
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• v.13 no.2
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• pp.111-118
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• 2015

Purpose: The purpose of this study was to describe the effects of proprioceptive neuromuscular facilitation (PNF) on episodes of foot drop and the ability to cross obstacles in stoke patients. Methods: The patient was a 57-year-old man with left hemiplegia. This patient displayed episodes of foot drop while walking and issues with crossing obstacles. The patient underwent therapeutic exercises and occupational therapy twice daily at a hospital five times a week. The patient was treated with PNF outside of these therapeutic sessions. Each session, which was 60 minutes in length, was conducted 3 times a week over 8 weeks. Over the course of treatment, a pre-test and post-test were completed. The patient walked for a test time of 6M. During the testing process, the patient crossed obstacles. In addition, the number of foot drop episodes was recorded. Each test was measured three times to determine the mean value. Results: After the PNF treatments, the number of foot drop episodes decreased from five to one. The 6M walking test time during which the patient crossed obstacles also decreased from 18 seconds to 10 seconds. Conclusion: The use of PNF treatments is beneficial to reduce the number of foot drop episodes while walking and to improve the ability to cross obstacles in stroke patients.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.63-69
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• 2007

The evaporation pressure drop of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and an evaporator (test section). The test section consists of a smooth, horizontal stainless steel tube of 4.57 mm inner diameter. The experiments were conducted at saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$, and heat flux of 10 to $40kW/m^2$. The test results showed that the evaporation pressure drop of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. The measured pressure drop during the evaporation process of $CO_2$ increases with increased mass flux, and decreased saturation temperature. The evaporation pressure drop of $CO_2$ is much lower than that of R 22. In comparison with test results and existing correlations, the best fit of the present experimental data is obtained with the previous correlation. But existing correlations failed to predict the evaporation pressure drop of $CO_2$. Therefore, it is necessary to develop reliable and accurate predictions determining the evaporation pressure drop of $CO_2$ in a horizontal tube.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.134-140
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• 2016

The Control Rod Assembly (CRA) controls the reactor power by adjusting its position in the reactor core during normal operation and should be quickly inserted into the reactor core by free drop under scram condition to shut down chain reactions. Therefore, the drop time of the CRA is one of important factors for the safety of the nuclear reactor and must be experimentally verified. This study presents the drop performance test of the CRA which has been conceptually designed for the Proto-type Generation IV Sodium-cooled Fast Reactor. During the test, the CRA was free dropped from a height of 1 m under different flow rate conditions and its drop time was measured. The results showed that the drop time of the CRA increased as the flow rate increased; the average drop times of the CRA were approximately 1.527 seconds, 1.599 seconds and 1.676 seconds at 0%, 100% and 200% of design flow rates, respectively.

• Journal of KSNVE
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• v.4 no.3
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• pp.345-352
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• 1994

Electronic products can be subjected to many different forms of shock. These shocks are usually experienced during transporting the electronic products from a manufacturer to customers. Drop tests are performed to test the product fragility before shipment. Package cushioning materials are often used to protect electronic products from severs shock environments. In the present paper, an algorithm to predict the shock responses of the main mechanical parts is developed by use of the shock analysis in which the modal parameters extracted from vibration test are used. These results are in good agreement with the results of drop test. By use of the shock response prediction algorithm developed herein, it is possible to predict the results of drop test at various drop directions and also to select the optimal package cushioning materials.