• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.11
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• pp.1036-1041
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• 2008

According to previous report, aged sleeves of old transmission line showed several defaulted installation patterns, which was biased or corrosive-fractured of steel sleeve installed cases. These defects can cause serious accidents such as rapid increasing of sag or falling out of overhead conductor from sleeves. Consequently, the defects lead to the major power outage. Corrosion of steel sleeve is a typical defect by aging of sleeves. And it occupied almost 25 percent of investigated aged sleeves. This paper studied thermal properties and tension for ACSR conductor in case of fractured steel sleeve model by corrosion. The temperature distribution within overhead conductor has a specific gradient. Thermal properties of splice connectors(sleeve and clamp) showed normal behavior. However, mechanical properties were worse than normal sleeves. The detailed results were presented in the text.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.832-845
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• 2024

Reactor cavity cooling systems (RCCSs) comprising passive safety features use the atmosphere as a coolant, which cannot be lost. However, their drawback is that they are easily affected by atmospheric disturbances. To realize the commercial application of the two types of passive RCCSs, namely RCCSs based on atmospheric radiation and atmospheric natural circulation, their safety must be evaluated, that is, they must be able to remove heat from the reactor pressure vessel (RPV) surface at all times and under any condition other than under normal operating conditions. These include both expected and unexpected natural phenomena and accidents. Moreover, they must be able to eliminate the heat leakage emitted from the RPV surface during normal operation. However, utilizing all of the heat emitted from the RPV surface increases the degree of waste heat utilization. This study aims to understand the characteristics and degree of passive safety features for heat removal by comparing RCCSs based on atmospheric radiation and atmospheric natural circulation under the same conditions. It was concluded that the proposed RCCS based on atmospheric radiation has an advantage in that the temperature of the RPV could be stably maintained against disturbances in the ambient air.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.446-452
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• 2018

A traffic route is an area associated with high risk for accidents due to the flow of heavy traffic. Despite this concern, most studies related to traffic focus solely on traffic distribution. Therefore, there is a need for studies investigating the characteristics of ships' routes and traffic patterns. In this study, an investigation was carried out to analyze the traffic distribution and pattern in 3 major traffic routes for 3 days. For the purpose of the study, based on the prevailing traffic conditions, the route was divided into 10 gate lines. The ships passing through the lines were also classified into either small, medium and large. ND-K-S (normal distribution, kurtosis, and skewness) test was carried out for the traffic distribution at each gate line based on the information analyzed on each traffic route. The analysis of the results obtained from the ND test showed that large vessels have normal distribution, medium sized vessels have satisfied normal distribution in one-way route only while small sized vessels do not have normal distribution. According to the result obtained from the K-S test, normal traffic pattern shows a significant difference between two-way route and one-way route. Results obtained from the K test result shows that in the case of one-way route, vessels have a traffic pattern using a wide range on traffic route. Further analysis shows that vessels concentrate on one side of route in case of two-way route. Results obtained from the S test show that, in case of one-way route, vessels have a normal traffic pattern according to center line. However, analysis pf the results shows that vessels are shifted to the right side of route in case of two-way route. Despite these findings, it should be noted that this study was carried out in only 3 ports, therefore there is need for investigation to be carried out in various routes and conditions in future studies.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.107-116
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• 2002

Crash Cushion is a kind of safety facilities on roadside which acts the role of absorbing impact energy when vehicles are driven out of normal route such as Gore area of freeway off ramp. Criteria for severity index considering accident occurrence possibility are needed to have strong effect on installing the facilities. However, present criteria for establishing crash cushion design do not include such processes. Therefore, the paper presents two kinds of study to develop criteria for severity index. First of all, development of accident forecasting model on freeway off ramp is presented. The module is a relationship between accidents and road environment by negative binomial distribution (NB) which is called to reflect very well quality of accidents at Gore of crash cushion installed freeway Secondly, freeway exiting behavior model is developed because the human factor is the most important one. However, many literatures have shown between road environment and accidents which are more quantitative than human factor. The study supposed advanced process steps on actual freeway and analysed correlation between variables and accidents. The criteria for severity index is presented to determine whether to install or not by benefit cost analysis for each module. The standard for severity index will help to determine whether to install the crash cushion or not and to estimate severity for freeway and off ramp.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.63-68
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• 2005

In this study, the arc dispersion properties were analyzed according to switching of high sensitive type Residual Current Protective Device(RCD) contacts. Arc dispersion and ignition process was taken by high speed imaging system(HSIS). In this experiment, electric lamps(60 W) and heaters(950 W) were connected in parallel as loads. In case of normal RCD, it took about 2.3(ms) from the generation of arc to the extinction of uc. When arc was dispersed in normal RCD, it did not ignite cotton. Whereas, in case of RCD deteriorated by NaCl solution, the range of arc dispersion was wider and the arc lasted for 3.3[ms] more compared to normal RCD. And the arc ignited cotton. In order to prevent accidents caused by RCD, we should be careful of environmental factors, such as dust and humidity, and the parts of RCD should be used as incombustible materials.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.836-842
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• 2016

When an accident occurs in the nuclear power plant, the faulted information might mislead to the high possibility of aggravating the accident. At the Fukushima accident, the operators misunderstood that there was no core exposure despite in the processing of core damage, because the instrument information of the reactor water level was provided to the operators optimistically other than the actual situation. Thus, this misunderstanding actually caused to much confusions on the rapid countermeasure on the accident, and then resulted in multiplying the accident propagation. It is necessary to be equipped with the function that informs operators the status of instrument integrity in real time. If plant operators verify that the instruments are working properly during accident conditions, they are able to make a decision more safely. In this study, we have performed various tests for the fault detection sensitivity of an data-driven empirical model to review the usability of the model in the accident conditions. The test was performed by using simulation data from the compact nuclear simulator that is numerically simulated to PWR type nuclear power plant. As a result of the test, the proposed model has shown good performance for detecting the specified instrument faults during normal plant conditions. Although the instrument fault detection sensitivity during plant accident conditions is lower than that during normal condition, the data-drive empirical model can be detected an instrument fault during early stage of plant accidents.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.31-34
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• 2013

According to the increase in numbers and operation time of domestic Nuclear Power Plants, KHNP(Korea Hydro & Nuclear Power) has many operating experiences. These show that most of the accidents repeatedly occurred not by the new sources or mechanism like the Fukushima Accident, but by the human and equipment errors from normal habits, process, design, maintenance etc.. These lessons show that the well-established systematic approach is requested to take lessons from past experiences. For this reason, developed countries established INPO, WANO, COG as a non-profit professional organizations to actively share their operating experiences. KHNP is also trying to promote the utilization of operating experiences. As part of this effort, KHNP is developing the KHNP-JIT, reflecting the overseas JIT and the domestic experiences.

• Journal of Institute of Convergence Technology
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• v.9 no.1
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• pp.25-30
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• 2019

Normal cranes cannot be used to move the fan inside the high-rise factories. Due to the size of the fan and safety accidents, there is a need for a structure capable of lifting and transporting. In this study, the safety of the structure was evaluated by considering the center of gravity of the fan and the effect of the fan being tilted up. An analysis of the buckling was performed by hand calculation. Nonlinear analysis was performed using ABAQUS to evaluate the safety of the structure. The safety factor for buckling is above 4.0 and the safety factor for stress is calculated to be 1.31 under the worst load distribution conditions.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1471-1473
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• 2004

A portable train approaching warning device can be used in order to reduce accidents of the workers on the rail, who are working without recognizing the approaching train, and to secure the safety of the workers. It can be installed in the train so that workers can recognize the approaching train. However, it is not easy to identify the location of the train precisely. In this study GPS and RF devices, which are used to calculate the location of the train were reviewed, to see how much error tolerance they have in the field, to analyze the distance for normal transmission between the receiver and transmitter, to verify the conformity of the portable train approaching warning device developed as a prototype model to the current rail system, and to provide the related fields with the analysis results to improve the existing or application technology. Additionally, test methods to locate the train were introduced and each test result was compared and analyzed.

• Journal of Chest Surgery
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• v.29 no.3
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• pp.355-359
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• 1996

Rupture of the main bronchus due to blunt chest trauma is very rare, especially In childhood although the incidence is increasing. Early diagnosis and primary repair not. only restore normal lung function but also avoid the difficulties and complications associated with delayed diagnosis and repair. We experienced 2 cases of right main bronchial rupture caused by traffic accidents. Patients suffered from progressively developing dyspnea and subcutaneous emphysema on the neck, anteriorchest,andanteriorabdominalwall. Emergency operations were performed through right posterolateral thoracotomy incision at the 4th intercostal space. Intraoperatively, the right main bronchus completely transsected and separated. Corrective bronchoplasty was performed with end-to-end anastomosis using interrupted suture with 3-0 Vicryle and the suture line was reinforced with azygos vein and parietal pleural flap. Postoperative courses were uneventful and patients discharged without any specific pro lems.