• Journal of the Ergonomics Society of Korea
• /
• v.26 no.1
• /
• pp.93-97
• /
• 2007

As many as 111 reactor trips have occurred for recent 5 years('01-'05), and 26 cases of them have occurred due to human error. The trend of human error rate didn't decrease in 2004, so KHNP started to make efforts to decrease human errors. In 2006 KHNP bench marked excellent foreign nuclear power plants and introduced human error prevention tools. In addition, KHNP created as many as 40 posters for human performance improvement. The posters are based on the about 500 real incident reports collected through K-HPES from 1995. Therror preventive tols for the poster. This paper explains design of the posters and their application.

• Journal of the Korean Society of Industry Convergence
• /
• v.8 no.4
• /
• pp.197-204
• /
• 2005

It is well known that pipelines have the highest capacity and are the safest and least environmentally disruptive form of transporting oil and gas. However, pipeline damages caused by both internal and external corrosion is a major concern threatening the reliability of oil and gas transportation and the soundness of pipeline structure. In this study, we estimated the expected allowable damage defect by comparing the ASTM B31G code which has been developed as the evaluation method of reliability and incident prevention of damaged pipelines based on the amount of loss due to corrosion and the yield strength of materials to a modified theory considering diverse detailed corrosional forms. Furthermore, we suggested the method that estimates the expected life span of used pipelines by utilizing the reliability method based on major variables such as, the depth and length of damage and corrosional rate affecting the life expectancy of pipelines.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.33 no.4
• /
• pp.187-192
• /
• 2010

Korean railway has run about 110 years since 1989 and played a great role of industrialization in Korea. It is known that rail transport systems have many advantages of being more safe, energy-efficient, and environment-friendly, as compared to other transportation systems. However, railway incidents are often attributed to the failure of safety management and critical to the efficiency of railroad industry. This study reviewed economic, financial, and general statistical information on Korea Railroad. Based on the statistical data, the effect of accidents on railroad management was analyzed. Correlation analysis revealed that railway accident had a negative effect on the gross profit of Korea Railroad. In order to reduce potential risks and incident rate, some recommendations are proposed. Actual or potential applications of this research include safety guidelines for improving efficiency of railroad industry.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.634-637
• /
• 2004

This paper presents a Split Hopkinson Pressure Bar(SHPB) technique to obtain compressive stress-strain data for rubber materials. An experimental technique that modifies the conventional Split Hopkinson Pressure Bar(SHPB) has been developed for measuring the compressive stress-strain responses of materials with low mechanical impedance and low compressive strengths such as rubber. This paper introduces an all-polymeric pressure bar which achieves a closer impedance match between the pressure bar and the specimen materials. In addition, we are a pulse shaper to lengthen the rising time of the incident wave to ensure stress equilibrium and homogeneous deformation of a rubber materials. It is found that the modified technique can be determine the dynamic deformation behavior of an NBR rubber more accurately.

• Journal of Mechanical Science and Technology
• /
• v.16 no.9
• /
• pp.1084-1092
• /
• 2002

The frequency dependency of Rayleigh surface wave is investigated indirectly by measuring the angular dependency of the backward radiation of the incident ultrasonic wave in two kinds of degraded specimens by scuffing or corrosion. Then, the frequency dependency is compared with the residual stress distribution or the corrosion-fatigue characteristics for the scuffed or corroded specimens, respectively. The width of the backward radiation profile increases with the increase of the variation in residual stress distribution for the scuffed specimens. In the corroded specimens, the profile width decreases with the increase of the effective aging layer thickness and is inversely proportional to the exponent, m, in the Paris' law that can predict the crack size increase due to fatigue. The result observed in this study demonstrates high potential of backward radiated ultrasound as a tool for nondestructive evaluation of subsurface gradient of material degradation generated by scuffing or corrosion.

• Nuclear Engineering and Technology
• /
• v.4 no.3
• /
• pp.223-228
• /
• 1972

In the radiography, of thick materials the scattered rays from an object are one of major causes to reduce the quality of the radiographic image on the film. To determine the rate of scattering of incident gamma rays by an objective specimen, film blacknesses are measured for various slit widths. For each measurement, the changes of a penetrameter's sensitivity are also evaluated. It is observed that the fault-detectability can be improved by reducing the slit width when the fault detectability deteriorates due to the increase in scattered gamma rays by thicker samples. This experiment has been carried out with the iron specimens and $^{60}$ Co source.

• Journal of Korean Vacuum Science & Technology
• /
• v.3 no.2
• /
• pp.139-144
• /
• 1999

Hydrogen concentration depth profiles in homoepitaxial Si(001) films grown from hyper-thermal Si beams generated by ultrahigh vacuum (UHV) ion-beam sputtering have been measured by nuclear reaction analyses as a function of film growth temperature and deposition rate. Bulk H concentrations CH in the crystalline Si layers were found tio be below detection limits, 1${\times}$1019cm-3, with no indication of significant H surface segregation at the crystalline/amorphous interface region. This is quite different than the case for growth by molecular-beam epitaxy (MBE) where strong surface segregation was observed for similar deposition conditions with average CH values of 1${\times}$1020cm-3 in the amorphous overlayer. The markedly decreased H concentrations in the present experiments are due primarily to hydrogen desorption by incident hyperthermal Si atoms. Reduced H surface coverages during growth combined with collisionally-induced filling of interisland trenches and enhanced interlayer mass transport provide an increase in critical epitaxial thicknesses by up to an order of magnitude over previous MBE results.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.6
• /
• pp.923-930
• /
• 2008

The butterfly valve is widely used in the industrial field as an on-off or a flow control valve. When the butterfly valve is used as a flow control valve. cavitation sometimes occurs in the range of high flow rate because of the small valve opening. Therefore. the pressure loss and the cavitation characteristics are investigated by use of a commercial CFD code. The results show that the possibility of cavitation occurrence in the cryogenic butterfly valve is very high in the case of valve opening angle below 10 degree and incident velocity over 6m/s. By increasing the inlet velocity at 10 degree of valve opening angle. the value of loss coefficient increased. However. by increasing the inlet velocity at 50 degree of valve opening angle. the value of loss coefficient decreased.

• Korean Journal of Optics and Photonics
• /
• v.7 no.1
• /
• pp.60-65
• /
• 1996

Degradation of the optical communication system due to the stimulated Brillouin scattering effect in the optical fiber is measured, and its suppression is demonstrated. In the externally modulated 2.5 Gb/s transmission experiment, bit error rate is increased due to the stimulated Brillouin scattering effect when the signal power (linewidth 3 MHz) incident into the dispersion shifted fiber is larger than 10 dBm. SBS effect is suppressed completely, up to 15 dBm of transmission power, by broadening the source linewidth to 200 MHz.

• Korean Journal of Veterinary Service
• /
• v.18 no.2
• /
• pp.103-112
• /
• 1995

Seasonal incident rates were examined from the 981 pigs slaushtered in southern Kang-won and distribution of lesions and histopathological examination were conducted from 231 Enzootic pneumonia affected lungs. The results obtained were summarized as follows： 1. 39.7∼50.2% of 981 slaughtered pigs showed pneumonia lesions without seasonal variation and the incidence rate of Enzootic pneumonia was 23.5% 2. The distribution of Lesions of Enzootic pneumonia lobes was observed. The right lobes were affected more frequently than the left, and the highest frequency of 79.7% being recorded in the right cardiac lobe followed by the left cardiac, right apical, intermediate, left apical, right diaphrogmatic and diaphrogmatic. 3. In histopatological observation lung lobes were forming Iymphonodulus from perivascular, peribronchiolar Iymphoid hyerplasia and it was remarkable to bronchostenosis.