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오진헌,임기조,임종남,이승수 한국전기전자재료학회 2009 Transactions on Electrical and Electronic Material Vol.10 No.6
The practical applications of piezoelectric ceramics are applied not only under low electric field environment. Therefore, an examination for characteristics of PZT ceramics under the high electric field condition can contribute to reducing the susceptibility of multifarious applications and to facilitating production of control circuits. These contributions can lead to the expansion of industrial applications. In this research, we fabricated disk-type PZT ceramic samples using conventional methods, measured the resonance characteristics of these samples under from low to high voltage conditions and calculated the PZT constants.
Design and Prototyping of a Novel Type Piezoelectric Micro-pump
오진헌,임종남,이승수,허준,임기조 한국전기전자재료학회 2008 Transactions on Electrical and Electronic Material Vol.9 No.5
Using the extensional vibration mode of PZT ring, a piezopump is successfully made. The PZT ring is polarized with thickness direction. The traveling extensional wave along the circumference of the ring is obtained by dividing two standing waves which are temporally and spatially phase shifted by 90 degrees from each other. The proposed piezopump is consisted of coaxial cylindrical shells that are bonded piezoelectric ceramic ring. The pump takes an unobtrusive operation into the simple displacing mechanism using peristaltic traveling waves without the physical moving parts. The finite elements analysis on the proposed pump model is carried out to verify its operation principle and design by the commercial FEM software. Components of piezopump were made, assembled, and tested to validate the concepts of the proposed pump and confirm the simulation results. The performance of the proposed piezopump is about 580 µl/min in flow rate with the highest pressure level of 0.85 kPa, when the driving voltage is 150 Vp, 57 kHz.
오진헌,임종남,이승수 한국전기전자재료학회 2009 Transactions on Electrical and Electronic Material Vol.10 No.5
In an ultrasonic motor, a piezoelectric ceramic material forms the active element which vibrates the stator, thus initiating the rotational motion. In the operation of ultrasonic motors, many factors exist that can affect the resonance characteristics of the piezoelectric ceramic component. For examples, these factors are the bonding conditions with the piezoelectric element, the magnitude of the input voltage, the normal force in the frictional drive and the emission of heat due to vibration and friction etc. Therefore, it is important to research properly the inclination for variation of piezoelectric ceramics in the circumstance where complex elements are involved. In this paper, we focus on the analysis of the resonance characteristics of an ultrasonic motor as a function of the magnitude of the input voltage and the normal force.
진헌철,오성찬,류석용,김홍용 대한응급의학회 2003 대한응급의학회지 Vol.14 No.3
A hepatoblastoma is the most common liver tumor in children between 6 months to 3 years of age. It is a rare malignancy of the liver with an incidence of 0.7 to 1 case per 1 million children under 15 years of age in Western countries. Males are more affected. Patients usually have normal liver funtion test, but have high serum levels of alpha-fetoprotein(AFP), which is a sensitive diagnostic marker. They usually present with abdominal distension or an asymptomatic abdorninal mass. Rarely, patients with a hepatoblastoma show an acute abdominal emergency which is not typical for the disease process. The management of a ruptured hepatocellular carcinoma provides guidance for diagnosis and treatment of a hepatoblastoma because the incidence of hepatoblastoma is low. We report a child who presented abdominal pain and distension with the diagnosis of a ruptured hepatoblastoma.
안성훈,김양원,김미란,진헌철,안지영,이상래,류석용,김홍용,김성준,이병권,김경환 대한응급의학회 2001 대한응급의학회지 Vol.12 No.2
Background: A hyperosmolar nonketotic state has been known to have a high mortality, and even now, despite this high mortality, only a few studies of this disease have been performed. We studied the prognostic factors for the hyperosmolar nonketotic state. Methods: We retrospectively studied the cases of 40 patients who were in a hypersomolar nonketotic state when admitted to Sanggye Paik Hospital during the 6-year Period from 1995 through 2000. We divided the hyperosmolar nonketotic patients into two groups, the complete recovery group and the incomplete recovery group, and compared the clinical features, the laboratory findings, and the precipitating factors between two groups. Results: 1) A total of 40 patients were studied: 24 in the complete recovery group and 16 patients in the incomplete recovery group. The mortality rate was 32.5%. 2) No significant statistical difference existed among the clinical features of the two groups, except for the sex(p<0.01). 3) Among the laboratory findings of both groups, analysis revealed that the effective osmolarity was significantly higher among those in the incomplete recovery group(p<0.01). Serum sodium concentration was also significantly higher among those in the incomplete recovery group(p<0.01). Serum creatinine was also significantly higher among those in the incomplete recovery group(p<0.05). Serum bicarbonate concentration, on the other hand, was significantly lower among those in that group(p<0.05).4) Infection was identified as the most common precipitating factor(62.5%). Among the precipitating factors of the two groups, there were significant statistical difference in pneumonia, UTI, and inappropriate glucose control. 5) A significant statistical difference existed among the initial level of consciousness of both groups(p<0.05). 6) The only significant independent factor responsible for prognosis of nonketotic hyperosmolar state patients was the sex. Conclusion: The sex was only significant independent prognostic factor of nonketotic hyperosmolar state patients.