• Proceedings of the KSR Conference
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• 2007.05a
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• pp.816-823
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• 2007

Electric car tract plays the role of supply high electric power to the electric car from the substation by using Pantograph of the electric car. It is always exposed to the external atmosphere, which results in quite substantial fluctuations in current and voltage during operation of electric car. This generates possibility of occurrence of accident at all times. Since range of wiring metallic globe installed on the catenary cannot achieve complete electrical contact, accidents are occurring due to circulating current caused by arc caused by incomplete contact due to occurrence of hairline fracture of Pantograph due to pressure or vibration of wiring. Furthermore, rapid increase in the operational current due to increase in the operational frequency of the electric car is causing erosion and short circuit of the metallic globe at the contact points. This study on arc is generated as current transmitted out of the substation courses through power line or wiring metallic globe other than the main circuit as the current is being collected at the electric car through feeder and feeder divergence device. Accordingly, since heat generated by the arc becomes the cause for generation of circulating current due to melting of metal or softening of metal due to increase in temperature accompanying increase in contact resistance, this research shall describe causes and measures against occurrence of circulation current.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.1
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• pp.40-50
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• 2013

This study is aimed to find a control factor for the marine casualty of fishing vessel by using the risk quantitative method of marine casualty, and sequentially timed event analysis for the reason finding. The result is that collision, sinking, and capsizing took high risk need to be strongly controlled. And the accident reason and control factors distinguished are as follows. The 82.2% of collided fishing vessels have negligence of look out as a immediate cause, while it was judged that underlying causes were the characteristics of vessels and fishing method, lack of suitable complement, fatigue, the prejudice or ignorance on steering and sailing rules. So the control factors are; firstly needs educational control measures and in terms of systemic control approach expand the range of the certificate of competency more smaller tonnage.

• Journal of forensic and investigative science
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• v.2 no.2
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• pp.67-91
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• 2007

The nature of deaths occurred at sea may be revealed the differences from that in the land, but there is no comprehensive statistical analysis of deaths occurred at Korean Sea so far. Therefore, the cases of deaths or missing in the period 1993 - 2006 were analyzed by the cause, place of death, and results of preliminary investigation. In the period from 1993 to 2006, over 1000 peoples were died or missing every year. The cases of marine safety accidents including self-carelessness and mishap were approached over 60% and cases of homicide were less than 1%. The closure cases of preliminary investigation were reached over 70% and the most of deaths occurred in fishing vessels (the range of 20 ~ 99 tonnage). The suspension cases of preliminary investigation were reached to 70% of all missing and drowning cases. The results showed that the most of deaths occurred at sea could be prevented by the safety regulations including mandatory report of accidents, marine safety education and training, punishment the people responsible for the accidents. For the unidentified bodies, data should be collected and recorded for the future identification. The crime scene investigators should be trained to ensure the quality of their professional skills regularly.

• Journal of the Korean Society of Safety
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• v.24 no.5
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• pp.13-20
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• 2009

The risk assessment of thermal hazard to identify chemical or process hazard during early process developments have been considered. The early identification of thermal hazards associated with a process, such as rapid heats of reaction, exothermic decompositions, and the potential for thermal runaways before any large scale operations are undertaken. This paper presents to evaluate the safe operating parameters/envelope for exist plant operations. The assessment of thermal hazard with operating conditions such as amount of process materials, inhibitor, and catalyst on esterification process in manufacture of concrete mixture agents are described. The experiments were performed by a sort of calorimetry with the Multimax reactor system as a screening tool. The aim of the study was to evaluate the thermal risk of process material and mixture in terms of safety security to be practical applications in esterification process. It suggested that we should provide the thermal hazard of reaction materials to present safe operating conditions with cause of accident through this study.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.21-26
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• 2018

Approximately 20% of the total fire is electrical fire, and electrical energy is a potential source of heat. Large-scale fault currents that occur during a line ground fault flow into electric utility poles, electric power equipment, or electric appliances of the customer, and cause simultaneous electrical fire. In this paper, we investigated the possibility of fire through the change of fault current flowing in faulty and sound feeder in case of 1 line ground fault in 22.9 kV distribution line. We propose a fire investigation analysis method for simultaneous multiple electrical fire such as evidence analysis method, and fault current occurrence confirmation method in case of fire accident by analyzing the fault current occurring in the ground fault in the distribution line using EMTP, electric power system analysis program.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.247-253
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• 2015

Dielectric breakdown accidents have been mainly occurred in the vicinity of service entrance section in underground power transmission systems. One cause among them is due to the excessive component value of sheath located around service entrance of cable. In this paper, as one of the alternative to prevent these accidents, the change of cross bond grounding system and the location change of IJ(Insulation Joint) are suggested. Also, to evaluate effectiveness of this changing system, circulating current and induced voltage of sheath were analyzed in steady and transient state. By comparison of the analytical results for the several possible changing systems, a grounding system and location of IJ which has the smallest sheath component values is proposed. In this paper, analysis to evaluate the proposed system is carried out by EMTP/ATPDraw. It can be used as a valuable operational material to prevent accident of the service entrance section in underground power transmission system.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.16 no.3
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• pp.190-194
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• 2013

Internal hernia (IH) is a rare cause of small bowel obstruction occurs when there is protrusion of an internal organ into a retroperitoneal fossa or a foramen in the abdominal cavity. IH can be presented with acute or chronic abdominal symptom and discovered by accident in operation field. However, various kinds of imaging modalities often do not provide the assistance to diagnose IH preoperatively, but computed tomography (CT) scan has a high diagnostic accuracy. We report a case of congenital IH in a 6-year-old boy who experienced life threatening shock. CT scan showed large amount of ascites, bowel wall thickening with poor or absent enhancement of the strangulated bowel segment. Surgical exploration was performed immediately and had to undergo over two meters excision of strangulated small bowel. To prevent the delay in the diagnosis of IH, we should early use of the CT scan and take urgent operation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.2
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• pp.136-143
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• 2013

The analysis of the written verdicts in recent five years was conducted to obtain preventive measures of collision between fishing vessel and non fishing vessel. As a result, a collision much happened in offshore trap for fishing vessel and below 5,000 tons of small and medium class for non fishing vessel. A person involved in a marine accident occupied 68% in sixth class deck officer and small boat operator for fishing vessel and 29% in third class deck officer for non fishing vessel. 90% of the collision happened in a underway by operating state and 84% in sight of one another by visibility state. The systemic radar training was required since 47% of the collisions was occurred on the condition of radar operation in fishing vessel. The main cause of poor lookout was a intensive fishing and poor lookout on movement by radar for fishing vessel and one man watch system and no recognition of one another by radar for non fishing vessel. This result is expected to contribute for the decrease of collision.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.145-152
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• 2022

Recently, interest in the precast concrete (PC) construction method has been increasing. The PC construction process consists of i) design, ii) production, iii) transportation, and iv) installation. A PC field manager at the site submits a shipment request form to the factory one to three days before the installation of the PC component. Numerous matters should be considered in writing a shipment request form. Incorrect shipment request forms may cause standby resources, waste of resources, premature work conclusion, or excessive work. These issues can lead to an increase in construction costs, replanning of PC component installation, or rework. In order to prevent such problems, PC component installation should be simulated based on the shipment request form. Accordingly, this study aims to identify factors influencing the operability of shipment request forms for PC construction. To this end, this study derived factors influencing i) initiation of the activity, ii) addition or deletion of activities, and iii) an increase or decrease in the activity execution time. As a result, this study identified flow, the features of PC components, condition of PC components, unloading location, installation location, input equipment and labor, number of anchors, number of supports, weather, strike, and accident. Further studies should verify the factors derived in this study based on focus group interviews.

• Journal of the Ergonomics Society of Korea
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• v.32 no.1
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• pp.139-144
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• 2013

Objective: The current study investigated a non-obtrusive measure for detecting physical fatigue based on the analysis of formant frequencies of human voice. Background: Fatigue has been considered as a main cause in industrial and traffic accidents. Therefore, it is critical to detect worker's fatigue for accident prevention. Method: After running exercises on a treadmill, participants were instructed to read a sentence and their voices were recorded under four different physical fatigue levels. Korean vowels of "아", "어", "오", "우", and "이" from the voice recorded were then used to collect formant 1 frequencies. Results: Results of separate ANOVAs showed a significant main effect of physical fatigue on formant 1 frequency of "아", "어", and "이". Furthermore, post-hoc comparisons revealed that formant 1 frequency of "아" was most sensitive to physical fatigue level employed in this experiment. Conclusion: Formant 1 frequencies of some vowels significantly decrease as the physical fatigue level increases. Application: Potential application of this study includes the development of a measure of physical fatigue state that is free from sensor attachment and requires little preparation.