• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1273-1279
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• 2016

Flow boiling pressure drop in multi channels was experimently investigated. The multi channel has a width and depth of 0.45 and 0.2mm respectively, and comprises 15 parallel channels. The measured total pressure drop is expressed by the sum of the frictional pressure drop and acceleration pressure drop. In order to predict the total pressure drop, it is required to obtain the correct frictional pressure drop. The existing correlations to predict the frictional pressure were compared with measured frictional pressure drop. The new correlation was developed in the form of the Chisholm correlation. It was related to Chisholm Constant B as a function of Martinelli parameter. The new correlation predicted the experimental data within a mean absolute error of 5.5%.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.246-250
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• 2005

The forward voltage drop of IGBT is studied numerically and analytically as a function of gate length. An analytical expression is presented for the first time for the surface potential variation along the channel layer under the gate of IGBT. The surface potential drop and the carrier density near the surface allow calculation of the forward voltage drop of IGBT analytically as a function of the gate length. The voltage-drop in the drift region near the gate decreases exponentially, whereas that on the surface increases linearly with increasing the gate length, the sum of which exhibits an optimum gate length, resulting in a minimum forward voltage drop. Based on the surface potential drop, a remodelling of the forward voltage drop of IGBT is also proposed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.723-730
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• 1998

With the introduction of edge drop control system in Tandem Cold Rolling Mill, it is necessary to develop te numerical expression for the set-up and edge drop automatic control of cold rolled sheet. As a first step we developed a simulation program which predicts profile and the amounts of edge drop at the delivery side of each stand by using roll deformation anlysis with the slit roll model. And by using the program the effect of various rolling conditions on edge drop was investigated. As a result the relations were obtained between the amounts of edge drop and rolling conditions. Based on above relations, the numerical expression was developed for the set-up and automatic control of edge drop by multi-regression of simulation results for the variation of edge drop amount with each rolling condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.87-95
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• 2002

The aim of this article is to perform the numerical simulation far drop drag and breakup processes in air-assisted sprays using the Taylor analogy breakup (TAB) model with a modified drop drag model, in which a random method is newly used to consider the variation of the drop's frontal area. The predicted results for drop trajectory and Salter mean diameter (SMD) were compared with experimental data and the simulation results using the earlier published models such as TAH model, surface wave instability (Wave) model, and Wave model with original drop drag model. In addition, the effects of the breakup model constant, Ck, on prediction of spray behaviors were discussed. The results shows that the TAB model with the modified drop drag model is in better agreement with experimental data than the other models, indicating the present model is acceptable for predicting the drop breakup process in air-assisted sprays. At higher Weber numbers, the smaller Ck shows the best fitting to experimental data. It should be noted that more elaborated studies is required in order to determine the breakup model constant in the suggested model in the study.

• 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.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.922-929
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• 2019

This paper presents the drop performance test of the control rod assembly which is one of the main components strongly related to the safety of the prototype generation IV sodium-cooled fast reactor. To investigate the drop performance, a real-sized control rod assembly that was recently modified based on the drop analysis results was newly fabricated, and several free drop tests under different flow rate conditions were carried out. Then the results were compared with those obtained from the previous tests conducted on the conceptually designed control rod assembly to demonstrate the improvement in performance. Moreover, the drop performance tests under several types and magnitudes of seismic loadings were also conducted to investigate the effect of the seismic loading on the drop performance of the modified control rod assembly. The results showed that the effects of the type and magnitude of the seismic loading on the drop performance of the modified control rod assembly were not significant. Also, the drop time requirement was successfully satisfied, even under the seismic loading conditions.

• 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.

• Physical Therapy Rehabilitation Science
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• v.5 no.2
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• pp.89-94
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• 2016

Objective: This study was aimed to compare the thickness and pennation angle of gastrocnemius through ultrasonography during the heel-drop exercise on ankle dorsiflexion angle. Design: Cross-sectional study. Methods: Nineteen normal adults in their 20s had voluntarily participated in this study. All subjects performed the ankle heel-drop exercise with ankle dorsiflexed to $0^{\circ}$, $10^{\circ}$, and $20^{\circ}$: heel-drop exercise with ankle dorsiflexed to $0^{\circ}$ was executed on floor-level, heel-drop exercise with ankle dorsiflexed to $10^{\circ}$ on a wooden-block of 2.3 cm in height, and heel-drop exercise with ankle dorsiflexed to $20^{\circ}$ on a wooden-block of 5.5 cm in height. In each regimen, the subjects completed a session of 100 heel-drop exercises (10 repetitions${\times}$10 sets; with 30 seconds rest following each set; with 24 hours rest following each exercise). Before and immediately after each heel-drop exercise, the thickness and pennation angle of gastrocnemius were measured using an ultrasonography. Results: After the performance of the heel drop exercises with ankle dorsiflexed to $0^{\circ}$, $10^{\circ}$, and $20^{\circ}$, the thickness of the gastrocnemius was significantly higher than pre-exercise (p<0.05), and furthermore heel-drop exercise with ankle dorsiflexed to $10^{\circ}$ was significantly higher than exercise with the ankle dorsiflexed to $0^{\circ}$ (p<0.05). However, as for the pennation angle of the gastrocnemius, there were no significant changes after each heel-drop exercise. Conclusions: This finding suggest that the heel-drop exercise with ankle dorsiflexed to $0^{\circ}$, $10^{\circ}$, and $20^{\circ}$ is effective on the strengthening of the gastrocnemius. Furthermore, the heel-drop exercise with the ankle dorsiflexed to $10^{\circ}$ is more effective than with the ankle dorsiflexed to $0^{\circ}$.

• Fashion & Textile Research Journal
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• v.7 no.5
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• pp.494-500
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• 2005

This study classifies somatotype from exact measurements according to the women somatotype with different drop value and isfunctional and has high body fitness. This study was preceded in the following process. Took 147 women in their 20's measurement directly and grasped the general body characteristic, and classified somatotype according to distribution of drop. Drop value is classified into Drop I, Drop II, and Drop III. Drop I is the difference value between bust line and waist line measurement. Drop II is the difference value between hip line and waist line measurement. Drop III is the difference value between hip line and bust line measurement. Suggested distribution of somatotype based on drop istribution. Classified somatotype into 4 types according to the mixture of combination of Drop I, II, and III. Comprehended the characteristics of somatotype based on basic statistical data. Type 1, M type, displays 40 % distribution that is most high distribution rate among four types and it is normal type which is similar to average value in size in the this study. Type 2, A type, displays 32.4% and it's a lower half of their body developed type with a flat busted and hippy. Type 3, X type, displays 19% and it's a healthy type with tall height, slender waist and curves of bust and hip lines. Type 4, H type, displays 8.6% and it's a biggest type in size which is busty, full hipped and nearly has no curves of body line.

• 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.