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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Safety
Journal Basic Information
Journal DOI :
The Korean Society Safety
Editor in Chief :
Volume & Issues
Volume 28, Issue 6 - Oct 2013
Volume 28, Issue 5 - Sep 2013
Volume 28, Issue 4 - Aug 2013
Volume 28, Issue 3 - Jun 2013
Volume 28, Issue 2 - Apr 2013
Volume 28, Issue 1 - Feb 2013
Selecting the target year
Evaluation of Fatigue Endurance for an MTB Frame
Kim, Taek Young ; Lee, Man Suk ; Lim, Woong ; Kim, Ho Kyung ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 1~5
DOI : 10.14346/JKOSOS.2013.28.3.001
In order to evaluate fatigue endurance for an MTB(mountain bike) frame, FEM(finite element method) analysis was performed. For evaluating the fatigue endurance of the MTB frame, the S-N data for Al-6061 fillet weldment were compared with the stress analysis results through FEM analysis of the frame. Three loading condition, pedalling, horizontal and vertical loading conditions were considered for fatigue endurance evaluation. Horizontal loading(+1200 N) condition was found to be the most severe to the frame. The maximum von Mises stress of the frame under horizontal loading(+1200 N) condition was determined 294 MPa through FEM analysis of the frame. Conclusively, on the basis of fatigue strength of 200 MPa at the number of cycles of 50,000, the MTB frame has an improper safety factor of approximately 0.25, suggesting that this frame needs reinforcement.
Creep Rupture Life Prediction of High Temperature HRSG Tubes
Kim, Woo Joong ; Kim, Jae Hoon ; Jang, Jung Cheol ; Kim, Beom Soo ; Lee, Gi-Chun ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 6~10
DOI : 10.14346/JKOSOS.2013.28.3.006
The Heat Recovery Steam Generator(HRSG) is a device recycling the exhaust gas of gas turbine in combined power and chemical plants. Since service temperatures was very high, the damage of HRSG tubes intensively occurred in superheater and reheater. The aim of this paper is to determine life and hardness relationship that addresses creep-rupture test and creep-interrupt test in modified 9Cr-1Mo steel. The measured life that consists of function of hardness was found to constant tendency.
Forensic Engineering Study on the Evaluation of the Structural Stability of the Mobile Crane Accident
Kim, Jong-Hyuk ; Kim, Eui-Soo ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 11~17
DOI : 10.14346/JKOSOS.2013.28.3.011
Forensic Engineering is the area covering the investigation of products, structures that fail to perform or do not function as intended, causing personal injury or damage to property. To investigate the mobile crane's overturn accident in terms of the forensic engineering, in this study, we identified the accident mobile crane's position and posture before accident by the analysis of the trace resulted by the contact between the outrigger and the ground, and the accident remodeling has been performed using CATIA modeling program in the basis of the accident mobile crane's position and posture information. The accident analysis has been performed by comparing this accident remodeling and the crane's specification, the table of the allowance load about the boom's length and the working radius. Through these studies, the safety accident that may occur in mobile crane can be minimized by performing specialized and systematic investigation of the accident cause in terms of the forensic engineering.
Low Cycle Fatigue Behavior of Cobalt-Base Superalloy ECY768 at Elevated Temperature
Yang, Ho-Young ; Kim, Jae-Hoon ; Ha, Jae-Suk ; Yoo, Keun-Bong ; Lee, Gi-Chun ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 18~22
DOI : 10.14346/JKOSOS.2013.28.3.018
The Co-base super heat resisting alloy ECY768 is employed in gas turbine because of its high temperature strength and oxidation resistance. The prediction of fatigue life for superalloy is important for improving the efficiency. In this paper, low cycle fatigue tests are performed as variables of total strain range and temperature. The relations between strain energy density and number of cycle to failure are examined in order to predict the low cycle fatigue life of ECY768 super alloy. The lives predicted by strain energy methods are found to coincide with experimental data and results obtained from the Coffin-Manson method. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.
ECO Driving Patterns Derived from the Analysis of the Problems of the Current Driving Pattern of Electric Multiple Unit in ATO System
Kim, Kyujoong ; Lee, Keunoh ; Kim, Juyong ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 23~28
DOI : 10.14346/JKOSOS.2013.28.3.023
This study focuses on finding ways to derive train's optimal ECO driving pattern, which can improve the ride quality and reduce driving energy consumption with keeping the time interval between the stations. As research method, we compared difference of currently operating train's ATO and MCS driving patterns, and concentrated upon the things need to consider in simulation in order to improve the existing pattern of ATO driving pattern's issues with securing the train operation safety. Determining driving pattern minimizing energy consumption by controlling powering within speed limit and controlling switching to coasting at appropriate point considering the track conditions for each section, and determining braking control starting time considering ride comfort and precise stopping is considered to be most important.
A Case Study on the Fracture of Steering Apparatus for Aircraft
Park, Sung-Ji ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 29~32
DOI : 10.14346/JKOSOS.2013.28.3.029
An aircraft made an emergency landing through the loss of capability controlling steering. A torsion link which is a part of steering apparatus has been adrift from the steering system and the bolt connected to the steering link has fractured. At the same time, the FLIR(Forward Looking Infrared Radar) mounted in front of the steering link has been also damaged. In the early of this investigation, we considered the failure of the FLIR had occurred first, that FLIR hit the steering link and finally the bolt fractured. The fractured section of the bolt has shown a beach mark and a dimple mark as well. The outside of the bolt has shown a large deformation by a heavy load. As a result, we have found out what the cause of the heavy load and the fractures for bolt, link and FLIR have occurred in what order.
The Development of Outsole for Wet Traction Enhancement
Kim, Jung Soo ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 33~38
DOI : 10.14346/JKOSOS.2013.28.3.033
Many occupational workers or professionals have to walk on the various floors for a long period of time. The objective of this study was to develop the safety shoes with increased traction through the material selection. In order to fulfill our objective, first, two kinds of filler were selected to compare the wear mechanism at outsole surface. The developed rubber materials were tested with two kinds of portable slip meters. The sample safety shoes with developed rubber materials were also tested with subject in the laboratory. During walking, the safety shoes were naturally abraded with counter surface. The coefficient of friction(COF) was gradually decreased with number of steps to 30,000, while the COF was abruptly increased from 30,000 to 40,000. The experimental results showed that COF tested with silica rubber was at least 10% higher than that with carbon black rubber in wet or detergent condition. It has been well recognized that filler properties play a important role in wet traction in the tire industry. However it has been unclear that filler properties would be decisive factor in safety shoes. Our study shows that silica exhibits a higher slip resistance than carbon black without reference to wear states in wet or detergent condition. So, this results will provide guides for outsole compounders to develop new products and improve product performance.
Experimental Study of Fire Characteristics of a Tray Flame Retardant Cable
Kim, Sung Chan ; Kim, Jung Yong ; Bang, Kyoung Sik ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 39~43
DOI : 10.14346/JKOSOS.2013.28.3.039
The present study has been conducted to investigate the fire combustion properties and fire behavior of an IEEE-383 qualified flame retardant cable. The reference reaction rate and reference temperature which are commonly used in pyrolysis model of fire propagation process was obtained by the thermo-gravimetric analysis of the cable component materials. The mass fraction of FR-PVC sheath abruptly decreased near temperature range of
and its maximum reaction rate was about
[1/s]. For the XLPE insulation of the cable, the temperature causing maximum mass fraction change was ranged about
and it has reached to the maximum reaction rate of
[1/s]. The flame retardant cable was burned by a pilot flame meker buner and the burning behavior of the cable was observed during the fire test. Heat release rate of the flame retardant cable was measured by a laboratory scale oxygen consumption calorimeter and the mass loss rate of the cable was calculated by the measured cable mass during the burning test. The representative value of the effective heat of combustion was evaluated by the total released energy integrated by the measured heat release rate and burned mass. This study can contribute to study the electric cable fire and provide the pyrolysis properties for the computational modeling.
Structural Integrity Evaluation by System Stress Analysis for Fuel Piping in a Process Plant
Jeong, Seong Yong ; Yoon, Kee Bong ; Duyet, Pham Van ; Yu, Jong Min ; Kim, Ji Yoon ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 44~50
DOI : 10.14346/JKOSOS.2013.28.3.044
Process gas piping is one of the most basic components frequently used in the refinery and petrochemical plants. Many kinds of by-product gas have been used as fuel in the process plants. In some plants, natural gas is additionally introduced and mixed with the byproduct gas for upgrading the fuel. In this case, safety or design margin of the changed piping system of the plant should be re-evaluated based on a proper design code such as ASME or API codes since internal pressure, temperature and gas compositions are different from the original plant design conditions. In this study, series of piping stress analysis were conducted for a process piping used for transporting the mixed gas of the by-product gas and the natural gas from a mixing drum to a knock-out drum in a refinery plant. The analysed piping section had been actually installed in a domestic industry and needed safety audit since the design condition was changed. Pipe locations of the maximum system stress and displacement were determined, which can be candidate inspection and safety monitoring points during the upcoming operation period. For studying the effects of outside air temperature to safety the additional stress analysis were conducted for various temperatures in
. Effects of the friction coefficient between the pipe and support were also investigated showing a proper choice if the friction coefficient is important. The maximum system stresses were occurred mainly at elbow, tee and support locations, which shows the thermal load contributes considerably to the system stress rather than the internal pressure or the gravity loads.
Study on the Causes of Malfunctions of PCBs Applied to the Power Saving Mode of Electrical Systems and its Solution
Park, Hyung-Ki ; Choi, Chung-Seog ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 51~55
DOI : 10.14346/JKOSOS.2013.28.3.051
The purpose of this study is to find the causes of malfunctions and defective operation of printed circuit boards(PCBs) built into home refrigerators to perform power saving functions. This study performed an electrostatic test of a PCB built-in using an Auto Triggering system; lightning and impulse tests using an LSS-15AX; and an impulse test using an INS-400AX. From the analysis of a secondarily developed product, it was found that electrostatic discharge(ESD) caused more malfunctions and defective operations than electric overstress(EOS) due to overvoltage. As a result of increasing the condenser capacity of the PCB circuit, withstanding voltage was increased to 7.4 kV. In addition, this study changed the power saving mode and connected a varistor to the #2 pin of an IC chip. As a result, the system consisting of all specimens of a finally developed product was operated stably with an applied voltage of less than 10 kV. This study found it necessary to perform quality control at the manufacturing stage in order to reduce the occurrence of electrostatic accidents to IC chips built into a PCB.
A Study on the Measurement of Electric Resistance of Footwear
Choi, Sang-Won ; Lee, Seokwon ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 56~62
DOI : 10.14346/JKOSOS.2013.28.3.056
The occurrence of the ventricular fibrillation is directly dependent on the magnitude and duration of the current. The current which flows through the human body is proportional to the touch voltage applied across the body and is in inverse proportion to the impedances in the circuit. The circuit impedances consist of human body impedance, line impedance, equipment impedance, earth terminal impedance and impedance of shoes which a person put on. The impedance of shoes greatly affect the severity of the electric accidents. The human body impedances relevant to the contact areas, contact conditions, current paths and touch voltages are already determined in the IEC 60479-1. However, the impedance of shoes is ignored or substituted by a simple value because of the absence of the sufficient data. For example, the impedance of shoes plus ground contact resistance is postulated to be
in the IEC 61200-612. In IEEE 80, the shoe resistance plus ground contact resistance is assumed to be bare foot with
. In this paper, we measured and analyzed the impedance of shoes with respect to conditions such as applied weight, environment variables and voltages. The results showed that the impedance of shoes is dependent on environment variables regardless of the types of shoes. Most of shoes showed the correlation with the applied force, whereas a few shoes showed characteristics related to the applied voltage. In terms of severity of electric shock, one thirds of test samples indicated to be dangerous in saltwater conditions.
Characteristics on Arc Waveform and RMS of Current by Conductive Powder
Kim, Doo Hyun ; Kang, Yang Hyun ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 63~68
DOI : 10.14346/JKOSOS.2013.28.3.063
This paper is aimed to make an analysis on characteristics of the parallel arc waveform and RMS of current at the electrical tracking state by conductive powder. In order to achieve the goal in this paper, field state investigation at metal processing companies in Chung-Nam province area was conducted. With the field state investigation, conductive powder were collected from metal processing companies. By experiment on electrical connector(breaker, connector) over which the conductive powder were scattered, arc waveform and RMS of current were measured. The measured waveform and RMS(root-mean-square) of current were analyzed to describe characteristics and patterns of electrical arc by the conductive powder. It was proved that conductive powder on electrical connector can flow electrical current enough to make electrical fire with high thermal energy. Also the change of sine waveform and RMS of current can be used to find out relationship between electrical fire and fault signal by conductive powder. The results obtained in this paper will be very helpful for the prevention of electrical fires occurred at the metal processing companies.
Damage Pattern and Operation Characteristics of a Thermal Magnetic Type MCCB according to Thermal Stress
Lee, Jae-Hyuk ; Choi, Chung-Seog ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 69~73
DOI : 10.14346/JKOSOS.2013.28.3.069
The purpose of this paper is to analyze the carbonization pattern and operation characteristics of an MCCB. The MCCB is consisted of the actuator lever, actuator mechanism, bimetallic strip, contacts, up and down operator, arc divider or extinguisher, metal operation pin, terminal part, etc. When the actuator lever of the MCCB is at the top or the internal metal operation pin is in contact with the front part, the MCCB is turned on or off. It means trip state if the actuator lever or the internal metal operation pin moves to back side. In the UL 94 vertical combustion test, white smoke occurred from the MCCB when an average of 17~24 seconds elapsed after the MCCB was ignited and black smoke occurred when an average of 45~50 seconds elapsed. It took 5~6 minutes for the MCCB surface to be half burnt and took an average of 8~9 minutes for the MCCB surface to be entirely burnt. In the UL 94 test, the MCCB trip device operated when an average 7~8 minutes elapsed. If the MCCB trip has occurred, it may have been caused by an electrical problem such as a short-circuit, overcurrent, etc., as well as fire heat. From the entire part combustion test according to KS C 3004, it was found that the metal operation pin could be moved to the MCCB trip position without any electrical problems.
A Study for Characteristics of Water that Penetrates Wood Flour due to Changes of Concentration of BDG
Kong, Il-Chean ; Park, Il-Gyu ; Lim, Kyung-Bum ; Rie, Dong-Ho ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 74~79
DOI : 10.14346/JKOSOS.2013.28.3.074
As the feature of fire, it is hard for deep-seated fire to spread to the deeper site, and it also has danger for being re-ignited cause of recontacting with oxygen after being put off. Now it is ruled in the certification criteria of wetting agent used for extinguishing deep-seated fire that the criteria for surface tension is below 33[mN/m] in Korea. For figuring out how much water for fire-fighiting can permeate into combustibles, in this research, the permeating performance is analyzed by measuring the speed of permeating and transmission quantity released after that, by pouring solution whose surface tension is changed by adjusting concentration of surfactant BDG(Butyl Di Glycol) in column From this result, it is can be determined that transmission quantity becomes less and wet area goes wider as surface tension is lower, and it is also able to be analyzed as quantity of absorbed liquid and wet area is increased because fluid permeates into the core.
Evaluation of Damage on a Concrete Bridge Considering the Location of the Vehicle Fire
Park, Jang Ho ; Kim, Sung Soo ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 80~87
DOI : 10.14346/JKOSOS.2013.28.3.080
Heat transfer analysis and thermal stress analysis for the concrete bridge was performed in order to investigate the damage of the concrete bridge by the fire of the vehicle. Changes in material properties, such as thermal conductivity, specific heat, density, elasticity, caused by temperature rise were considered. Heat transfer analysis and thermal stress analysis were performed according to the various location of the fire by ABAQUS. From the comparison of the numerical results, the degree of structural damage for the concrete bridge was investigated and considerations for the design of a concrete bridge against fire were identified.
A Study on the Hazard Identification of Laboratory using 4M ＆ HAZOP
Kim, T.H. ; Rhie, K.W. ; Seo, D.H. ; Lee, I.M. ; Yoon, C.S. ; Lee, Y.K. ; Park, J.I. ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 88~94
DOI : 10.14346/JKOSOS.2013.28.3.088
In university laboratories, areas of studies are becoming diverse and complicated according to the development of the industry. New forms of potential risk factors are increasing and they are unlike existing ones. In addition, many students are conducting various experiments in the laboratory. Therefore, they could be exposed to risk more often. Despite these risks, people do not recognize university lab safety activities properly and observe safety precautions. They are exposed to various laboratory accidents continually. In this study, we do not apply the present diagnosis method, checklist, but the safety assessment that is widely used in industry. Then we can find lots of hazard that checklist method could miss. This study will use the 4M and Hazard & Operability to design a new Laboratory safety assessments method.
A Study on the Risk Level of Work Types in Nuclear Power Plant Construction
Lee, Jong-Bin ; Lee, Jun Kyung ; Chang, Seong Rok ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 95~99
DOI : 10.14346/JKOSOS.2013.28.3.095
The goal of this study was to investigate some significant factors to influence level of safety at plant construction field and analyze degree of risk by work classification. Currently, there are lots of construction fields for the nuclear power plant for electricity generation, and our government also planned constructing more nuclear power plant in near future. However, much of the safety literature neglected the degree of risk factors on the plant construction field. Safety managers participated in the brainstorming session for drawing decision criteria of the degree of risk (i.e., significant factors). Then, they were asked to answer a structured questionnaire which was developed for drawing most important factors. Finally, the analytic hierarchy process (AHP) was used to analyze level of risk by work classification. The following results were obtained. First, total twelve factors judging degree of risk were found in the brainstorming session. Second, the questionnaire showed four significant factors, including number of workers, working environments, skill of craft and accident experience. Third, the results of AHP showed Architecture work is the most dangerous work among 6 work types. The results could be used to reduce degree of risk in construction field of the nuclear power plant.
A Study on the Work Ability and the Job Stress of the Workers in Manufacturing Industry of Automobile Parts
Mok, Yun-Soo ; Lee, Dong Won ; Chang, Seong Rok ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 100~106
DOI : 10.14346/JKOSOS.2013.28.3.100
According to the Statistics Korea, in 2011, people over the age of 65 years old accounted for 11.8% of Korea's population. This number is expected to rise to 15.0% by 2019, making Korea an "aged society". As age increases, physical ability degrades to the point that the workload must be adjusted limitations. However, workloads are given regardless of workers' ages or abilities. In addition, a decline in work efficiency due to aging also increases the risk of work-related injuries. Furthermore, the cases of stress related diseases along with musculoskeletal disorders(MSDs) rise as main factors of industrial disasters and excessive job stress gives negative influence not only on mental health but also on physical health so that job stress becomes a hot issue as a main cause of work ability falloff and turnover. The purpose of this research is to examine how the sociodemographic characteristics, MSDs symptoms and musculoskeletal workload of workers in the manufacturing industry of automobile parts influence work ability and job stress. As a result of the research, job ability showed significant differences statistically according to age, working year, sex, marital status and musculoskeletal workload and job stress showed significant differences statistically according to age, working year, marital status and musculoskeletal workload. In addition, it showed that as the worker's job ability decreases, job stress increases.
Variation of EEG Band Powers Related with Human Errors in Knowledge-based Responses
Lim, Hyeon-Kyo ; Kim, Hong-Young ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 107~113
DOI : 10.14346/JKOSOS.2013.28.3.107
Problem solving and/or decision making process usually encountered in human living consists of a sequence of human behaviors based upon his/her knowledge. Thus, Rasmussen introduced Skill-Rule-Knowledge paradigm to countermeasure human errors that can occur in Nuclear Power Plants. Unfortunately however, it was not so easy as expected since objective evidence have not been obtainable with conventional research techniques. With the help of EEG band pawer ratio techniques, this study tried to get psycho-physiological symptoms of human errors, if any, while human beings perform knowledge-based behaviors such as simple arithmetic computations with different difficulty level. A set of simulated works was carried out with a computer station. Four kinds of arithmetic computation tasks were given to 10 health male under-graduate students on different day individually, and during the experiment, EEG and ECG was measured continuously for objective psycho-physiological analysis. According to the results,
) as well as
band power ratio were sensitive to task difficulty level which consistently decreased both. However, any one of them failed to reveal the influence of tasks with different difficulty level in the aspect of task duration time. On the contrary, Heart Rate Variability was more suggestive than expected. To make a conclusion, it can be said that band power of EEG waves will be helpful in not only assessment of work difficulty level but also assessment of workers' skill development if supported by cardiac function such as HRV.
Accuracy of Paper-pencil Test used in Investigation of Control-display Stereotype - Focused on Stereotype for Control-burner Relationship of Four-stove Range -
Kee, Dohyung ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 114~117
DOI : 10.14346/JKOSOS.2013.28.3.114
The purpose of this study is to empirically investigate accuracy of paper-pencil test used in surveying control-display stereotype. For doing this, three paper-pencil tests dealing with stereotype for control-burner relationship of four-stove gas range, in which three different gas range images were provided, were performed and the results were compared with those of existing studies. The result of the paper-pencil test using simple image composed of line and circle was different from that of the real model simulation, while the results of the other two tests and a previous study providing more realistic images were the same as that of the real model simulation. Furthermore, the proportion of responses coinciding with the real model simulation increased as images used became closer to real range. It is concluded that the paper-pencil tests well designed using realistic images may produce the same stereotype as the real model simulation.
A Study for Optimal Evacuation Simulation by Artificial Intelligence Evacuation Guidance Application
Jang, Jae-Soon ; Kong, Il-Chean ; Rie, Dong-Ho ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 118~122
DOI : 10.14346/JKOSOS.2013.28.3.118
For safe evacuation in the fire disaster, the evacuees must find the exit and evacuate quickly. Especially, if the evacuees don't know the location of the exit, they have to depend on the evacuation guidance system. Because the more smoke spread, the less visibility is decreasing, it is difficult to find the way to the exit by the naked eye. For theses reasons, the evacuation guidance system is highly important. However, the evacuation guidance system without change of direction has the risk that introduce to the dangerous area. In the evacuation safety assessment scenario by the evacuation simulation has the same problem. Because the evacuee in the simulation evacuate by the shortest route to the exit, the simulation result is same like the evacuation without the evacuation guidance system. In this study, it was used with MAS (Multi Agent System)-based simulation program including the evacuation guidance system to implement the change of evacuation by fire. Using this method, confidence of evacuation safety assessment can be increase.
Safety Analysis of APR+ PAFS for CDF Evaluation
Kang, Sang Hee ; Moon, Ho Rim ; Park, Young Seop ;
Journal of the Korean Society of Safety , volume 28, issue 3, 2013, Pages 123~128
DOI : 10.14346/JKOSOS.2013.28.3.123
The Advanced Power Reactor Plus(APR+), which is a GEN III+ reactor based on the APR1400, is being developed in Korea. In order to enhance the safety of the APR+, a passive auxiliary feedwater system(PAFS) has been adopted in the APR+. The PAFS replaces the conventional active auxiliary feedwater system(AFWS) by introducing a natural driving force mechanism while maintaining the system function of cooling the primary side and removing the decay heat. As the PAFS completely replaces the conventional AFWS, it is required to verify the cooling capacity of PAFS for the core damage frequency(CDF) evaluation. For this reason, this paper discusses the cooling performance of the PAFS during transient accidents. The test case and scenarios were picked from the result of the sensitivity analysis in APR+ Probabilistic Safety Assessment(PSA). The analysis was performed by the best estimate thermal-hydraulic code, RELAP5/.MOD3.3. This study shows that the plant maintains the stable state without the core damages under the given test scenarios. The results of PSA considering this analysis' results shows that the CDF values are decreased. The analysis results can be used for more realistic and accurate performance of a PSA.