• Fire Science and Engineering
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• v.32 no.1
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• pp.57-65
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• 2018

In this study, a post-fire safe shutdown analysis (PFSSA) including multiple spurious operation (MSO) treatments for cables was conducted with an imaginary nuclear power plant for training using a deterministic fire analysis code. The imaginary nuclear power plant for the training consisted of a reactor containment building and an auxiliary building, including a total of 22 fire areas. The equipment including valves, pumps, emergency diesel generators, switch gears, motor control centers, and logic controllers were located in each fire area of the imaginary plant. It was assumed that each equipment is connected with two cables and that each cable passes through the fire areas along the cable trays. A database containing the information on the equipment and cables for the imaginary plant was constructed for the fire area analysis. The fire area analysis was performed for several assumed MSO scenarios, equipment logics, and cable logics. A mitigation measure using a three hour rated wrap was applied to the failed cables and cable trays after the fire area analysis.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.585-593
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• 2005

Recent concerns regarding protecting, identifying, isolating, redundant routing and dewatering of subsystems of water distribution networks have led to the realization of the importance of valves in these systems. Valves serve two purposes namely, flow and pressure control and isolating subsystems due to breakage or contaminant containment. In this paper, valves are considered from the point of view of subsystem isolation. When a water main is required to be closed, it may be in general necessary to close several other pipes in addition to the broken pipe itself depending on the distribution of adjacent valves. This set of pipes is defined as a segment. In this paper a segment analysis for isolating pipes is present and based on the segment analysis, we suggested the Valve Importance Index and the 7 performance indicators to evaluate the system performance. The suggested methodology is applied to a real network to verify the applicability of the methodology.

• Nuclear Engineering and Technology
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• v.46 no.3
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• pp.439-446
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• 2014

An amphibious inspection robot system (hereafter AIROS) is being developed to visually inspect the in-containment refueling storage water tank (hereafter IRWST) strainer in APR1400 instead of a human diver. Four IRWST strainers are located in the IRWST, which is filled with boric acid water. Each strainer has 108 sub-assembly strainer fin modules that should be inspected with the VT-3 method according to Reg. guide 1.82 and the operation manual. AIROS has 6 thrusters for submarine voyage and 4 legs for walking on the top of the strainer. An inverse kinematic algorithm was implemented in the robot controller for exact walking on the top of the IRWST strainer. The IRWST strainer has several top cross braces that are extruded on the top of the strainer, which can be obstacles of walking on the strainer, to maintain the frame of the strainer. Therefore, a robot leg should arrive at the position beside the top cross brace. For this reason, we used an image processing technique to find the top cross brace in the sole camera image. The sole camera image is processed to find the existence of the top cross brace using the cross edge detection algorithm in real time. A 5-DOF robot arm that has multiple camera modules for simultaneous inspection of both sides can penetrate narrow gaps. For intuitive presentation of inspection results and for management of inspection data, inspection images are stored in the control PC with camera angles and positions to synthesize and merge the images. The synthesized images are then mapped in a 3D CAD model of the IRWST strainer with the location information. An IRWST strainer mock-up was fabricated to teach the robot arm scanning and gaiting. It is important to arrive at the designated position for inserting the robot arm into all of the gaps. Exact position control without anchor under the water is not easy. Therefore, we designed the multi leg robot for the role of anchoring and positioning. Quadruped robot design of installing sole cameras was a new approach for the exact and stable position control on the IRWST strainer, unlike a traditional robot for underwater facility inspection. The developed robot will be practically used to enhance the efficiency and reliability of the inspection of nuclear power plant components.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.2
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• pp.109-119
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• 2006

This study investigated the effect of artificially enhanced mesozooplankton on the phytoplankton dynamics during fall blooming period using a mesocosm in Jangmok bay located in the Southern Sea of Korea in 2001. The four bags with 2,500 liter seawater containment were directly filled with the ambient water. And then, abundances of mesozooplankton in two experimental bags were treated 6 times higher than those in control bags by towing with net($300{\mu}m$) through the ambient water. Phytoplankton community between control and experimental bags were not significantly different in terms of chlorophyll-a(chl-a) concentration and standing crop (one-way ANOVA, p>0.05) during the study period. Initial high standing crop and chl-a concentration of phytoplankton drastically decreased and remained low until the end of the experiment in all bags. Diatoms, accounting for most of the phytoplankton community, consisted of Skeletonema costatum, Pseudo-nitzschia seriata, Chaetoceros curvisetus, Ch. debilis, Cerataulina pelagica, Thalassiosira pacifica, Cylindrotheca closterium, and Leptocylindrus danicus. Noctiluca scintillans dominated the temporal variation of mesozooplankton abundances, which peaked on Day 10 in the control and experimental bags, while the next dominant copepods showed their peak on Day 7. Shortly after mesozooplankton addition, copepod abundance in the experimental bags was obviously higher than that in the control bags on Day 1, however, it became similar to that in the control bags during the remnant period. It was supported by the higher abundance and length of both ctenophores and hydromedusae in experimental bags relative to the control bags. However, the cascading trophic effect, commonly leading to re-increase of phytoplankton abundance, was not found in the experimental bags, indicating that copepods were not able to control the phytoplankton in the bags based on the low grazing rate of Acartia erythraea. Besides that, rapidly sunken diatoms in the absence of natural turbulence as well as N-limited condition likely contributed the no occurrence of re-increased phytoplankton in the experimental bags.

• Health Policy and Management
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• v.2 no.2
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• pp.221-237
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• 1992

The reasons for cost inflation in medical insurance expenditure are classified into demand pull inflation and cost push inflation. The former includes increase in the number of beneficiaries and utilization rate, while the latter includes increase in medical insurance fee and the charges per case. This study was conducted to analyze sources of increases of expenditure in medical insurance demonstration area by the period of 1982-1987 which was earlier than national health insurance and the period of national health insurance(1988-1990). The major findings were as follows: Medical expenditure in these areas increased by 9.4%(15.1%) annually between 1982 and 1990 on the basis of costant price(current price) and for this period, the yearly average increasing rate of expenses for outpatient care[10.5%(15.8%)] was higher than that of inpatient care [7.3%(12.6%)]. Medical expenditure increased by 6.3%(8.9%) annually between 1982 and 1987, the period of medical insurance demonstration, while it increased by 10.7%(18.9%) after implementing national health insurance(1988-1990). Medical expenditure increased by 35.9%(45.9%) between 1982 and 1987. Of this increase, 115.2%(92.1%) was attributable to the increase in the frequencies of utilization per beneficiary and 61.0%(68.1%) was due to the increase in the charges per case, but the expenditure decreased by 76.2%(60.2%) due to the reduction in the number of beneficiaries. Beteen 1988 and 1990, the period of national health insurance, medical expenditure increased by 21.2%(41.4%). Of this increase, 87.5%(46.4%) was attributable to the increase in the frequencies of utilization per beneficiary and 52.4%(73.4%) was due to the increase in the charges per case, and of the increase in the charges per case, 69.6%(40.8%) was attributable to the increase in the days of visit per case. Medical expenses per person in these areas increased by 78.2%(89.0%) between 1982 and 1987. Of this increase, 76.6%(69.1%) was attributable to the increase in the frequencies of utilization per beneficiary and 23.4%(30.9%) was due to the increase in the charges per case. For this period, demand-pull factor was the major cause of the increase in medical expenses and the expenses per treatment day was the major attributable factor in cost-push inflation. Betwee 1988 and 1990, medical expenditure per person increased by 31.2%(53.1%). Of this increase, 60.8%(37.2%) was attributable to the demand-pull factor and 39.2%(62.8%) was due to the increase in the charges per case which was one of cost-push factors. In current price, the attributalbe rate of the charges per case which was one of cost-push factors was higher than that of utilization rate in the period of national health insurance as compared to the period of medical insurance demonstration. In consideration of above findings, demand-pull factor led the increase in medical expenditure between 1982 and 1987, the period of medical insurance medel trial, but after implementing national health insurance, the attributable rate of cost-push factor was increasing gradually. Thus we may conclude that for medical cost containment, it is requested to examine the new reimbursement method to control cost-push factor and service-intensity factor.