• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.943-953
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• 2021

The propagation of impact wave induced by landslide and debris flow occurred on the slope of lake, reservoir and bays is a three-dimensional natural phenomenon associated with strong interaction of debris flow and water flow in complex geometrical environments. We carried out 3D numerical modeling of such impact wave in a bay using a multiphase turbulence flow model and a rheology model for non-Newtonian debris flow. Numerical results are compared with previous experimental result to evaluate the performance of present numerical approach. The results underscore that the reasonable predictions of both thickness and speed of debris flow head penetrating below the water surface are crucial to accurately reproduce the maximum peak height and free surface profiles of impact wave. Two predictions computed using different initial debris flow thicknesses become different from the instant when the peaks of impact waves fall due to the gravity. Numerical modeling using relatively thick initial debris flow thickness appears to well reproduce the water surface profile of impact wave propagating across the bay as well as wave run-up on the opposite slope. The results show that the maximum run-up height on the opposite slope is not sensitive to the initial thickness of debris flows of same total volume. Meanwhile, appropriate rheology model for debris flow consisting of inviscid particle only should be employed to more accurately reproduce the debris flow propagating along the channel bottom.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.2 no.2
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• pp.79-84
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• 2009

Purpose: Medial or Lateral epicondylitis is one of the most common causes of elbow pain and recently ESWT (Extracorporeal Shockwave Therapy) is welcomed as a new treatment modality and has been performed in many clinics. The purpose of this study is to report the clinical result after the ESWT treatment for the lateral or medial epicondylitis of the elbow. Materials and Methods: From Nov. 2005 to Jan. 2009, seventy four cases of seventy two (11 male, 61 female) patients diagnosed as medial or lateral epicondylitis of the elbow are included in this study. The average age was 52.4 years old. Authors used visual analogue scale (VAS) to assess the degree of pain at rest and during work, comparing the score before the ESWT treatment with that of $6^{th}$, $12^{th}$ and $24^{th}$ week after the treatment. Authors also checked the number of awakeness during sleep due to pain and compared them before and after the ESWT treatment. Results: Average resting pain score improved from 4.60 before the treatment to 2.01 at $6^{th}$ week, 0.43 at $12^{th}$ week and 0.16 at $24^{th}$ week. Average pain score during working also showed quite an improvement with time from 7.20 before the treatment to 4.05 at $6^{th}$ week, 2.01 at $12^{th}$ week and finally 0.36 at $24^{th}$ week. We checked the frequency of sleep arousal during a week, and also found similar significant treatment efficacy as the average frequency decreased from 9.64 per week before the treatment to 1.21, 0.08 and 0.09 per week at $6^{th}$ week, $12^{th}$ week and $24^{th}$ week, respectively. Conclusion: ESWT for medial or lateral epicondylitis is thought to be one of the effective treatment modalities for those patient group not quite responsive to other conservative treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.125-132
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• 2019

Because the water exposed to shock waves caused by an underwater explosion cannot withstand the appreciable tension induced by the change in both pressure and velocity, the surrounding water is cavitated. This cavitating water changes the transferring circumstance of the shock loading. Three phenomena contribute to hull-plate damage; initial shock loading and its interaction with the hull plate, local cavitation, and local cavitation closure then shock reloading. Because the main concern of this paper is local cavitation due to a near-field underwater explosion, the water surface and the waves reflected from the sea bottom were not considered. A set of governing equations for the structure and the fluid were derived. A simple one-dimensional infinite plate problem was considered to verify this uncoupled solution approach compared with the analytic solution, which is well known in this area of interest. The uncoupled solution approach herein would be useful for obtaining a relatively high level of accuracy despite its simplicity and high computational efficiency compared to the conventional coupled method. This paper will help improve the understanding of fluid-structure interaction phenomena and provide a schematic explanation of the practical problem.