• Proceedings of the KSR Conference
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• 2006.11b
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• pp.786-790
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• 2006

Urban rail transit offers target performance and function because various lower part system such as rolling-stock, signal, power and trackis consisted as complex. In order to function properly an urban rail transit which is complicated system to work as safety and reliability, System must secure safety with structure, design, manufacture, install and verification and it is important to establish a safety standard follows it procedures, establish what step all it is important to operate. Safety standard of urban transit infrastructure is minimum standard necessary to secure safety of signal, power and track. Urban rail transit standard business leads to make many requirements. Recently, many types of equipment have applied to manage requirements and standards for system efficiently in part of universal, airline and car accordingly applied equipments use to manage a pursuit(Trace) between standard of system. Especially importance of management is emphasized more become more. Importance of standard management which usesa computing support tool recently in transit filed is embossed and is predicted to be more such forward. Therefore we propose the effective method of management with infrastructure system by constructed data-base system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.241-245
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• 2004

The electric safety tends to be more important according to electric facilities's increase and its use in these days. This paper analyzes soil resistivity of two areas in the country using CDEGS(Current Distribution, Electromagnetic Interference, Grounding and Soil Structure, Canada). We designed rod and mesh grounding system and made a comparative study of ground resistance, GPR(Main Electrode Potential Rin), step voltage and touch voltage. Then we could analyz only the safety but also economical efficiency in elocution of grounding. As a result of simulation, ground resistance, GPR(Main Electrode Potential Rise), step voltage and touch voltage became higher in proportion to soil resistivity. Therefore we expect to estimate the propriety of grounding system design through accumulation and analysis of data in consideration of characteristics of soil.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.599-604
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• 2005

As a public transportation possible to convey a large quantity, the railway is safe and keeps time, but it has hazards to cause a disaster if the accidents such as collision, derailment, and fire occur. So advanced countries carry out System Safety Plan with various program activities which have connected orders to maintain or improve safety level by finding hazards, evaluation, taking measures and practice, and improving problems. Especially they systematically manage hazards to cause railway accidents and the factors which possibly threat safety, using national classification of risk and causes with analysis of the related data such as establishing accident/incident data and safety regulations/standards. As executing railway safety regulations, domestic railway is currently trying to improve railway safety management system. The research of classification system of accidents/incidents is one thing to make railway safety management systems better. In this research, we reviewed hazardous factors of railway systems and classification of the causes as the beginning of system safety management, and we conducted study on development of railway accident classification based on findings of this research. The results are able to be used in identifying hazards and activities of systemic safety management at the step of railway accident report and investigation.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.218-221
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• 2005

Grounding electrodes as discharge paths to the earth are normally used to ensure the safety of human body and facilities from the over-voltages in distribution power system, and each grounding mode has a prescribed ground resistance value respectively which is applied by the utilities. As the various electrodes for distribution power system are recently developing to improve the performance of them and resolve the problem of space restriction, it is necessary to measure and investigate the safety of human body of developed electrodes. Therefore, in this paper, we provide briefly a technical comparison of two standards, i.e. IEEE Std 80 and the IEC 479-1, and describe the configuration of safety measurement system which can measure the step voltage and the touch voltage of grounding electrodes based on IEEE Std 80.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.2893-2905
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• 2024

Passive safety systems are integrated into the latest generation of Light Water Reactors (LWRs), including small modular reactors. This paper employs the US-NRC TRACE thermal hydraulic code to examine the performance of a passive safety condenser known as SACO, designed to serve as the ultimate heat sink for dissipating decay heat during accident scenarios. The TRACE model is constructed with reference to the PKL/SACO test facility. The safety condenser (SACO) is interconnected with the PKL facility via the secondary side of steam generator 1, effectively serving as a third natural circulation cooling loop during accident scenarios. In the present research, the thermal-hydraulic behavior of the PKL facility is investigated in the presence of the SACO passive safety system during an extended SBO with Loss of AC Power accident scenario. This SBO can be categorized into three distinct phases depending on the activation of the SACO system and the refilling process of the SACO pool. The first phase is depressurizing using primary and secondary relief valves, the second phase is cooling down using SACO system, and the third phase is the refilling of SACO pool. The findings indicate that the SACO system effectively manages to dissipate all decay heat, even though there is temporary evaporation of the SACO water pool. Furthermore, this study provides sensitivity analysis for the assessments of system codes on the selection of maximum time step.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.108-114
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• 2011

In order to mitigate the possible hazards from electric shock due to the touch and step voltages, the high resistivity material such as gravel is often spread on the earth's surface in substations. When the grounding electrode is installed in two-layer soil structures, the surface layer soil resistivity is different with the resistivity of the soil contacted with the grounding electrodes. The design of large-sized grounding systems is fundamentally based on assuring safety from dangerous voltages within a grounding grid area. The performance of the grounding system is evaluated by tolerable touch and step voltages. Since the floor surface conditions near equipment to be grounded are changed after a grounding system has been constructed, it may be difficult to determine the tolerable touch and step voltage criteria. In this paper, to propose an accurate and convenient method for evaluating the protective performance of grounding systems, the propriety of the method for evaluating the current flowing through the human body around on a counterpoise buried in two-layer soils is presented. As a result, it is reasonable that the grounding system performance would be evaluated by measuring and analyzing the current flowing through the human body based on dangerous voltages such as the touch or step voltages and the contact resistance between the ground surface and feet.

• Proceedings of the Safety Management and Science Conference
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• 2000.11a
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• pp.243-249
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• 2000

An improvement activity is necessary for the existence strategy of the corporate. We search effective activities by the integration, implemention of the Quality Control Circlle and the Suggestion Activity System on the various improvement activity. Therefore, Each of the concept and step are surveyed. We output the commonness and the difference, and propose "The Suggestion Circle Activity" that is the new integration, improvement activity. activity.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.3
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• pp.35-42
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• 2012

The database for driving patterns can be utilized in various system such as automatic driving system, driver safety system, and it can be helpful to monitor driving style. Therefore, we propose a driving pattern recognition system in which the sensor streams from a smartphone are recorded and used for recognizing driving events. In this paper we focus on the driving pattern recognition that is an essential and preliminary step of driving style recognition. We divide input sensor streams into 7 driving patterns such as, Left-turn(L), U-turn(U), Right-turn(R), Rapid-Braking(RB), Quick-Start(QS), Rapid-Acceleration (RA), Speed-Bump(SB). To classify driving patterns, first, a preprocessing step for data smoothing is followed by an event detection step. Last the detected events are classified by DTW(Dynamic Time Warping) algorithm. For assisting drivers we provide the classified pattern with the corresponding video stream which is recorded with its sensor stream. The proposed system will play an essential role in the safety driving system or driving monitoring system.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1008-1015
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• 2007

The primary purpose of the safety management is to prevent the loss of lives or physical damages arising from potential hazards in the railroad signaling system. Since such potential hazards may occur at any time during the system life cycle from design and development to maintenance, safety management activities have to be continuously taken in the course of the system life cycle. The identification of potential hazards is the early step of the safety management. However, such identification activities have to be continued during the system life cycle. Further, they have to be closely linked with system functions to prevent functional problems. This study provides a systematic approach to identification of potential hazards for their tracking and management during the system life cycle to assure the identification and definition of the most appropriate hazards.

• Journal of Power Electronics
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• v.19 no.4
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• pp.846-857
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• 2019

Voltage step-down converters are very popular in distributed power systems, voltage regular modules, electric vehicles, etc. However, a high step-down voltage ratio is required in many applications to prevent the traditional buck converter from operating at extreme duty cycles. In this paper, a series capacitor interleaved buck converter with a soft switching technique is proposed. The DC voltage ratio of the proposed converter is half that of the traditional buck converter and the voltage stress across the one main switch and the diodes is reduced. Moreover, by paralleling the series connected auxiliary switch and the auxiliary inductor with the main inductor, zero voltage transition (ZVT) of the main switches can be obtained without increasing the voltage or current stress of the main power switches. In addition, zero current turned-on and zero current switching (ZCS) of the auxiliary switches can be achieved. Furthermore, owing to the presence of the auxiliary inductor, the turned-off rate of the output diodes can be limited and the reverse-recovery switching losses of the diodes can be reduced. Thus, the efficiency of the proposed converter can be improved. The DC voltage gain ratio, soft switching conditions and a design guideline for the critical parameters are given in this paper. A loss analysis of the proposed converter is shown to demonstrate its advantages over traditional converter topologies. Finally, experimental results obtained from a 100V/10V prototype are presented to verify the analysis of the proposed converter.