• Journal of radiological science and technology
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• v.21 no.1
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• pp.40-45
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• 1998

To determine its usefulness and safety of extracorporeal shock-wave lithotripsy in common bile duct and pancreatic duct stones, we analyzed the results of 13 patients with common bile duct stones and 6 patients with pancreatic duct stones which were removed by endoscopic procedures using the balloon or basket, who was performed the extracorporeal shock-wave lithotripsy using the ultrasonography for stone localization with a spark gap type Lithotriptor(Dernier MPL 9000, Germany). Fragmentation and complete clearance of the common bile duct and pancreatic duct stones were obtained in 19 of 19 patients(100%). Apart from transient attacks of fever in 2 of 13 patients with common bile duct stones(15%) and mild elevation of serum amylase and lipase in 2 of 6 patients with pancreatic duct stones(33%), no other serious side effects were observed. In our experiences, extracorporeal shock-wave lithotripsy is a safe and useful treatment for endoscopically unretrievable common bile duct and pancreatic duct stones.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.2
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• pp.45-50
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• 2004

The field utilization factor (equation omitted) (the mean electric field / the maximum electric field) of standard sphere gaps was calculated by the charge simulation method, taking into account the ground plane and shanks. n changes mainly with g/r and slightly with 1$_1$, 1$_2$ and 1, where D=2r is the sphere diameter, g is the gap length, 1$_1$ and 1$_2$, respectively, are the lengths of the upper and lower shank, and t is the shank diameter. Generally, (equation omitted) increases as 1$_1$,1$_2$ and t each becomes larger. IEC standard 60052(2002) limits t$\leq$0.2D 1$_1$$\geq$1D and prescribes A=1$_2$＋D＋g where A is the height of the spark point on the upper sphere. Therefore, (equation omitted) is the largest when A=9D and the smallest when A=3D. The simple equation of a straight line, (equation omitted)=1- (g/3r), can generally be used as a representative value of (equation omitted) for a wide variety of sphere diameters that are permitted by the IEC standard. The maximum electric field E$_{m}$ at sparkover of standard air gaps has also been calculated by the relation E$_{m}$=V/(equation omitted)g). E$_{m}$ describes a U-curve for g/r, up to the sphere diameter of 1 m. Moreover, for 1.5-m and 2-m diameters and especially .for negative polarity, sparkover voltages have been calculated by integration of the ionization index.index.

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.323-332
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• 2005

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at the spark electrode gap and the combustion characteristics of a homogeneous charged methane-air mixture under various overall charge pressures, excess air ratios and ignition times. The flow characteristics, including the mean velocity and turbulence intensity, were analyzed with a hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer, a flame propagation image acquired by ICCD camera and exhaust emissions measured by 2-valve gas chromatography were used to investigate effects of initial pressures, excess air ratios and ignition times on the combustion characteristics. It was found that the mean velocity and turbulence intensity had the maximum value around 200-300 ms and then decreased gradually to a near-zero value after 3000 ms and that the combustion duration was shorten and the flame speed and laminar burning velocity had the highest value under the condition of an excess air ratio of 1.1, an overall charge pressure of 0.15 MPa and an ignition time of 300 ms in the present study. The $CO_2$ concentration was proportional to the ignition time and overall charge pressure, the $CO_2$ concentration was proportional to the excess air ratio, and the UHC concentration was inversely proportional to the ignition time and overall charge pressure.

• Journal of radiological science and technology
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• v.28 no.2
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• pp.105-110
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• 2005

Background/Aim : Common bile duct (CBD) stones may cause jaundice, cholangitis, or pancreatitis. Extracorporeal shock wave lithotripsy (ESWL) may be needed whenever endoscopic procedure are failed to extract common bile duct stones. The aim of this study is to provide the standard for patient's best choice on ESWL for treatment of CBD stones resistant to endoscopic extraction. Materials and Methods : Fourty-six patients failed in endoscopic stone extraction including mechanical lithotripsy were treated by ESWL. In all patients, endoscopic sphincterotomy and nasobiliary drainage tube was done before ESWL using the ultrasonography for stone localization with a spark-gap type lithotriptor. Patients were sedated with an intravenous injection of 50 mg of Demerol. None were treated under general anesthesia. Results : Overall complete clearance rate of CBD stone was 89.1% (41/46). In 82.6% of the patients, the stones were extracted endoscopically after ESWL, and spontaneous passage was observed in 6.5%. In the clearance rate after ESWL, there were no noticeable differences with regard to number (single: 82.8%, two or three: 100%, more than three: 100%) and size of the stone (less than 33mm: 92.9%, 33 mm or larger: 83.3%), whereas there were significant differences with regard to the ratio of sum of long-axis length of the all stones to sum of long-axis length of the CBD excluding stone (1:2.4, 1:2.1) and diameter of the largest stone to diameter of CBD excluding stone (1:0.9, 1:0.4) for patients with complete clearance compared with those without. Conclusion : We propose that stones without the fragments are travelable sufficient space in CBD or extractable sufficient diameter of CBD regardless of stone size and number should be treated by other technique to prevent time and cost consuming, such as percutaneous transhepatic cholangioscopylithotomy.