• Journal of The Korean Astronomical Society
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• v.35 no.3
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• pp.151-157
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• 2002

From the data of solar wind observation by ACE spacecraft orbiting the Earth-Sun Lagrangian point, we selected 48 forward interplanetary shocks(IPSs) occurred in 2000, maximum solar activity period. Examining the profiles of solar wind parameters, the IPSs are classified by their shock drivers. The significant shock drivers are the interplanetary coronal mass ejection(ICME) and the high speed stream(HSS). The IPSs driven by the ICMEs are classified into shocks driven by magnetic clouds and by ejectas based on the existence of magnetic flux rope structure and magnetic field strength. Some IPSs could be formed as the blast wave by the smaller energy and shorter duration of shock drivers such as type II radio burst. Out of selected 48 forward IPSs, $56.2\%$ of the IPSs are driven by ICME, $16.7\%$ by HSS, and $16.7\%$ of the shocks are classified into blast-wave type shocks. However, the shock drivers of remaining $10\%$ of the IPSs are unidentified. The classification of the IPSs by their driver is a first step toward investigating the critical magnitudes of the IPS drivers commencing the magnetic storms in each class.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.6
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• pp.20-28
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• 2021

High enthalpy test facilities, such as a shock tunnel, are to be operated at the specific pressure ratio according to the desired test condition. A metallic diaphragm is machined or a forced rupture device is used to open it at a specific pressure ratio. The diaphragm opening procedure takes several hundred microseconds including rupture and deformation. This process is expected to affect the test conditions. In this study, numerical simulation was performed for different materials, thicknesses, and opening ratios. And the characteristics of shock wave generation and the stagnation condition in the tube are investigated. Results show that the final opening ratio and rupturing procedure directly affect the speed of a shock wave, stagnation pressure, and test time.

• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.330-332
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• 2001

• Journal of radiological science and technology
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• v.25 no.2
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• pp.65-70
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• 2002

The pain of chronic pancreatitis associated intraductal stones is related to increased intraductal pressure. Decom-pression of the pancreatic duct along with extraction of stones are the goals of a combined endoscopic-extracorporeal shock wave lithotripsy approach. The aim of this study is to define radiographic prognostic criteria for better complete free rate of pancreatic head and body ductal stones for extracorporeal shock wave lithotripsy. Fifty-nine patients with chronic pancreatitis were treated by extracorporeal shock wave lithotripsy for endoscopically unretrievable stones. The stones on endoscopic retrograde pancreatograms were classified into four characteristics including number, size of longest diameter, density compared with vertebral body, and shape. Complete stone free were obtained in 45 of 59(76.3%). Pancreatic ductal stones with radiographic characteristics including higher density than vertebral body, square shape, and rim calcified stones were hindrance factors for extracorporeal shock wave lithotripsy. We propose that patients with rim calcified stone of our three hindrance factors should be treated by other technique.

• The Journal of the Acoustical Society of Korea
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• v.41 no.5
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• pp.589-600
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• 2022

In order to verify the reliability of Dry Test Bench (DTB) used for testing the output energy from ballistic extracorporeal shock wave therapeutic devices, the measurements with DTB were compared with the acoustic energy measured with a Laser Doppler Vibrometer (LDV) for a commercial ballistic ESWT device. It was shown that the mechanical energy detected with DTB had variability maintained within 5 % at the same output power setting and also had a linear correlation (adj. R² = 0.991) with the acoustic energy measured with the LDV for the entire output power settings. Using the correlation between the two methods and the correlation on the acoustic energy measured in between air and water with the LDV, the DTB measurement can be used to estimate the energy flux density in water with an average error of 7.85 % for the entire output power settings of the ballistic shock wave generator considered in the experiment. DTB provides information limited to the output mechanical energy and therefore it is not suitable for testing the various acoustic output parameters required in IEC61846 and IEC63045. However, DTB that is simple in measurement principles and easy to use is expected for manufacturers and clinical users to monitor the performance of ballistic Extracorporeal Shock Wave Therapy (ESWT) devices.

• The Journal of the Acoustical Society of Korea
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• v.42 no.5
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• pp.469-490
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• 2023

Survey was carried out on the acoustic outputs from 12 shock wave fields produced by the 10 extracorporeal shock wave lithotriptors whose technical documents are available, among the 33 devices approved by the Ministry of Food & Drug Safety (MFDS).The results show that the acoustic outputs (P+, P-, efd, and E), critical to the therapeutic efficacy and the patient safety, are largely different between the devices. The maximum values of P+, P-, efd, and E vary up to 2.08, 3.72, 3.89, and 15.98 times, respectively. The acoustic output parameters are not thoroughly provided in the technical documents, and some of data (eg. efd) are suspected to be abnormal outside usual ranges. The large device to device differences in the shock wave outputs are likely to undermine equivalence between the ESWL devices approved for the same indication. To verify the reliability of the data in the technical documents of the approved devices and to confirm if the acoustic outputs from the devices in clinical use are the same as those in their technical documents, an authorized test laboratory should be available. A postapproval monitoring led by the regulatory agency is suggested to maintain the acoustic outputs from the ESWL devices that suffer from degrading in performance due to aging.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.640-645
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• 2001

The present study is to investigate the characteristics of the impulse waves discharged from the exit of the convergent and divergent pipes. An experiment is carried out using a shock tube with an open end and is compared to the computation of the axisymmetric, compressible, unsteady Euler equations, which are solved by the second-order total variation diminishing(TVD) scheme. For the computational work, some initial compression waves are assumed inside the pipe so that those are identical to the experimental ones of the shock tube. The results show that the peak pressures of the impulse waves discharged from the exit of convergent and divergent pipes decrease with an increase in the wavelength of the initial compression wave. All of the impulse waves have a strong directivity toward the pipe axis, regardless of the exit type of the pipe employed. The impulse waves discharged from the divergent pipe are stronger than those from the straight pipe, while the impulse waves of the convergent pipe are weaker than those from the straight pipe. It is believed that the convergent pipe can playa role of a passive control to reduce the peak pressure of the impulse wave. The present computations represent the experimented impulse waves with a good accuracy.

• Steel and Composite Structures
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• v.27 no.3
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• pp.255-271
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• 2018

This paper deals with the transient dynamic analysis and elastic wave propagation in a functionally graded graphene platelets (FGGPLs)-reinforced composite thick hollow cylinder, which is subjected to shock loading. A micromechanical model based on the Halpin-Tsai model and rule of mixture is modified for nonlinear functionally graded distributions of graphene platelets (GPLs) in polymer matrix of composites. The governing equations are derived for an axisymmetric FGGPLs-reinforced composite cylinder with a finite length and then solved using a hybrid meshless method based on the generalized finite difference (GFD) and Newmark finite difference methods. A numerical time discretization is performed for the dynamic problem using the Newmark method. The dynamic behaviors of the displacements and stresses are obtained and discussed in detail using the modified micromechanical model and meshless GFD method. The effects of the reinforcement of the composite cylinder by GPLs on the elastic wave propagations in both displacement and stress fields are obtained for various parameters. It is concluded that the proposed micromechanical model and also the meshless GFD method have a high capability to simulate the composite structures under shock loadings, which are reinforced by FGGPLs. It is shown that the modified micromechanical model and solution technique based on the meshless GFD method are accurate. Also, the time histories of the field variables are shown for various parameters.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.318-324
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• 2010

Dynamic properties of materials by shock loads such as rock blasting and earthquake are recently attracted in the design of aboveground and underground structures. The advance of measuring devices enables to obtain the whole histories of stress and strain in rock specimen of which the failure is completed in several hundred microseconds. The SHPB has been a popular and promising technique to study the dynamic behavior of rock. And the dynamic compressive, tensile and other test with this experiment system are planned to be Suggested Methods of ISRM. This technical paper is to introduced one study article which focuses the design of 3S (special shaped striker) to produce the half-sine wave to eliminate the problems of the rectangular wave. This article is also describing the advantage of half-sine incident wave and size effect of rock dynamic strength.

• Physical Therapy Rehabilitation Science
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• v.3 no.2
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• pp.142-147
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• 2014

Objective: This study aims to investigate high energy and low energy extracorporeal shockwave therapy (ESWT) and which one is more effective for shoulder pain. Design: Single blind randomized controlled trial. Methods: Fifty two subjects with upper trapezius (UT) trigger point (TrP) participated in this study. They were allocated to high energy (n=26) and low energy group (n=26). This study applies ESWT and investigates the changes of pressure pain threshold (PPT) and visual analogue scale (VAS). The high and low energy groups received focused piezo electric type ESWT 4 Hz, 1,000 pulses and 0.351 and $0.092mJ/mm^2$ respectively. Outcome measures of PPT and pain was measured by algometer and pain VAS. These measurements were performed before and after treatment. Results: The PPT value was significantly increased in both groups after treatment (p<0.05) and VAS scores were significantly decreased after treatment in both groups (p<0.05). However, there were no significant differences between groups. Conclusions: ESWT is an effective treatment for the application of the UT TrP. Although there were significant effects of extracorporeal shock wave therapy on PPT and VAS scores, there were no signficant differences between high and low energy extracorporeal shock wave therapy.