To investigate the contribution of hepatitis C virus (HCV) to chronic liver disease and hepatocellular carcinoma (HCC) in Korea, antibodies to HCV (anti-HCV) were tested by enzyme immunoassay in 1759 patients with chronic liver disease and HCC, and in 808 healthy adults. The prevalence of anti-HCV was 1.6% in 808 controls. Anti-HCV was present in 32 (7.7%) of 418 hepatitis B surface antigen (HBsAg)-positive and 128 (53.1%) of 241 HBsAg-negative patients with chronic hepatitis, 16 (6.0%) of 265 HBsAg-positive and 90 (30.5%) of 295 HBsAg-negative patients with liver cirrhosis, and 16 (4.8%) of 330 HBsAg-positive and 61 (29.0%) of 210 HBsAg-negative patients with HCC. Antibodies to hepatitis B core antigen (anti-HBc) were present in 80-88% of patients who were seropositive for anti-HCV and seronegative for HBsAg. Among the sera from 114 patients with HBsAg-negative and anti-HCV-positive chronic liver diseases, HBV DNA and HCV RNA were detected by polymerase chain reaction (PCR) in 54 (47.4%) and 61 (53.3%), respectively. Both HBV DNA and HCV RNA were detected in 4 (4.4%) samples. The mean age of the patients with both HBsAg and anti-HCV was not different from that of patients who were seropositive for HBsAg alone. These findings indicate that current and/or past HBV infection is still the main cause of chronic liver disease in Korea.(ABSTRACT TRUNCATED AT 250 WORDS)

Research on human vibration is concerned with the response of the human body to the amounts, frequencies, directions, and exposure times of exerted forces. Processes have been developed to standardize these factors, and the typical examples are ISO 2631-1 and BS 6841, which are related to whole-body vibration and ISO 5349-1, which is related to handtransmitted vibration. Because ride comfort and human vibration are, in some sense, a mental and environmental problem that is influenced by psychological effects, human sensation in relation to vibration has both intra-and inter-subject variability. When the ride comfort index is defined as a physical quantity and is written as an equation, it is related to acceleration using both the r.m.s. (root mean square) and r.m.q. (root mean quadrature) as descriptors. In this study, two passenger cars were driven at several speeds over several road profiles to evaluate the subjective rating of ride comfort. To measure the acceleration signals that are transmitted to the feet, hip, back and hand, four tri-axial translational accelerometers and one tri-axial gyro sensor were mounted on the steering wheel and on the passenger seat and floor, respectively. Correlations were performed to determine the relationship between the measured accelerations and the subjective ratings of 4 expert drivers using a psychophysical power law. Regression models correlating the 5 subjective assessments were developed. Subjective ratings of the comfort at the hip had the highest correlation with the objective measurements.

SUMMARYIn this paper, we address analytical and numerical studies on the free vibration of uid-structure interaction problems considering the uid compressibility. According to the separation of variables together with the boundary condition enforcement, we ÿrst derive a compressible-uid velocity potential function. Next, we split the structure region into the wet and dry parts, for which we apply the Novozhilov thin shell theory. Combining two dynamic displacement ÿelds, for two split structure parts, using the displacement compatibility conditions, we ÿnally obtain a simultaneous equation system for computing natural frequencies and modes. According to the derived analytical formulae, we compute natural frequencies and modes, stress resultants, together with the comparison with the FEM analysis and the incompressible case. Numerical results show, compared to the incompressible case, that the compressible case produces lower natural frequencies and, furthermore, the relative di erence is in uenced by the slenderness of tanks and the relative liquid ÿll height.