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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 25, Issue 6 - Dec 2010
Volume 25, Issue 5 - Oct 2010
Volume 25, Issue 4 - Aug 2010
Volume 25, Issue 3 - Jun 2010
Volume 25, Issue 2 - Apr 2010
Volume 25, Issue 1 - Feb 2010
Selecting the target year
Study on Detection Technique for Outer-race Fault of the Ball Bearing in Rotary Machinery
Jeoung, Rae-Hyuck ; Lee, Byung-Gon ; Lee, Doo-Hwan ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 1~6
Ball bearings are one of main components that support the rotational shaft in high speed rotary machinery. So, it is very important to detect the incipient faults and fault growth of bearing since the damage and failure of bearing can cause a critical failures or accidents of machinery system. In the past, many researchers mainly performed to detect the bearing fault using traditional method such as wavelet, statistics, envelope etc in vibration signals. But study on the detection technique for bearing fault growth has a little been performed. In this paper, we verified the possibility for monitoring of fault growth and detection of fault size in bearing outer-race by using the envelope powerspectrum and probabilistic density function from measured vibration signals.
A Study of the Linear Analysis of an Equivalently Reduced System from the Original Torsional System
Ahn, Min-Ju ; Yoon, Jong-Yun ; Qi, Zhang ; Ahn, In-Hyo ; Lyu, Sung-Ki ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 7~14
In order to analyze the vibro-impacts in the torsional system, several clearance types of nonlinearities should be included with the analytical or numerical method. These kinds of nonlinear factors can cause the errors while the system is calculated specifically with the numerical method, also it might take too long to get right answers with the every nonlinearity in the original system. Therefore, there are several methods developed for the sake of overcoming the deficiency of the analysis with the original system and saving the calculating time. The original system can be reduced by keeping the system characteristics such as from 14 to 6 DOF. Especially, since the torque flow in the torsional system is connected with the specific gear ratios, the original system can be transferred into the simpler system corresponding to each gear ratio rather than the original system, which can also show the same system characteristics such as the natural frequencies and the mode shapes. By using the reduced system, the calculating time can be saved and the redundant nonlinear effects for the system analysis can be ignored without any numerical errors.
A Study on the Analysis of Design Parameters for Development of LSD
Shin, Young-Ho ; Lee, Dong-Won ; Shin, Chun-Se ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 15~21
A differential case equipped with LSD(limited slip differential) has several advantages over a normal type for rear wheel drive vehicles. Specially, the torque distribution can be done between left and right drive wheel in the state of limited slip differential. Also although LSD types are very various according to operating type, medium and torque distribution, a multi-clutch type is generally applied to rear wheel drive vehicles. So, this study presents the analysis of design parameters for development of a friction plate for multi-clutch type LSD using vehicle road test, the simulation of analytical model and the development of vehicle dynamics model by a benchmark product. According to this investigation, the design parameters which are pre-load of coil spring, friction plate and contact area quantity, friction coefficient and TBR(torque bias ratio) for a friction plate are derived from experiment and simulation and consequently, vehicle dynamics model has been constructed for the development of friction plate for multi-clutch type LSD.
A Comparison Study of the Prediction Performance of FDS Combustion Model for the Jet Diffusion Flame Structure
Park, Eun-Jung ; Oh, Chang-Bo ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 22~27
A prediction performance of Fire Dynamics Simulator(FDS) developed by NIST for the diffusion flame structure was validated with experimental results of a laminar slot jet diffusion flame. Two mixture fraction combustion models and two finite chemistry combustion models were used in the FDS simulation for the validation of the jet diffusion flame structure. In order to enhance the prediction performance of flame structure, DNS and radiation model was applied to the simulation. The reaction rates of the finite chemistry combustion models were appropriately adjusted to the diffusion flame. The mixture fraction combustion model predicted the diffusion flame structure reasonably. A 1-step finite chemistry combustion model cannot predict the flame structure well, but the simulation results of a 2-step model were in good agreement with those of experiment except
concentration. It was identified that the 2-step model can be used in the investigation of flame suppression limit with further adjustment of reaction rates
The Effect on the Strength According to Carbon Content of Kovar Steel
Choi, Byung-Hui ; Choi, Byung-Ky ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 28~33
Ni alloy steel is able to use during long time because of good acid and corrosion resistance. So, it's research has focused on developing the alternative alloy which is economically feasible. Recently, consumption of Kovar steel is gradually increased in field of the jet engine and the gas turbine because of its low thermal expansive characteristics. The specimens of Kovar steel(29%Ni-17%Co) contain 0.00%C, 0.03%C, 0.06%C, 0.10%C and 0.20%C, respectively. Ingots are manufactured by VIM(vacuum induction melting furnace) and then specimens are made by automatic hot rolling after heat treatment. Strength of Kovar steel according to carbon contents is estimated by hardness, tensile and impact test. Hardness of the 0.20%C specimen is more improved approximately 14.4% than one of base metal. Its strength increases 32.4% of a base metal, and its impact energy is also enhance 11.5%.
A Study of Mode II Interlaminar Fracture for CFRP Laminate Composite using the 4-point Bending CNF Specimen
Kwon, Oh-Heon ; Kang, Ji-Woong ; Tae, Hwan-Jun ; Hwang, Yeong-Yeun ; Yun, Yu-Seung ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 34~39
Unidirectional Carbon Fiber Reinforced Plastics (CFRP) are advanced materials which combine the characteristics of the light weight, high stiffness and strength. For those reasons, the use of the unidirectional CFRP has increased in jet fighters, aerospace structures. However, unidirectional CFRP composites have a lot of problems, especially delamination, compared with traditional materials such as steels and aluminums, and so forth. Therefore, the interlaminar fracture toughness for a laminate CFRP composite is very important. In this study, The mode II interlaminar fracture toughness was measured by using center notched flexure(CNF) test specimen. The CNF specimens using unidirectional carbon prepreg were fabricated by a hot-press with the gage pressure and temperature controller. And three kinds of a/L ratio was applied to these specimens. Here, we discuss the relations of the crack growth and the mode II interlaminar fracture under the four point bending CNF test. From the results, we shows that mode II interlaminar was occurred when the more
/L ratio, the less load. And
also were obtained as 5.33, 2.9 and
/L ratio=0.2, 0.3 and 0.4.
Analysis of Disaster with Casualty Caused by Malfunction of the Water Level Monitoring System in Imjin River
Song, Jae-Yong ; Nam, Jung-Woo ; Kim, Jin-Pyo ; Kim, Eui-Soo ; Park, Nam-Kyu ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 40~44
North Korea's discharge of water from a dam into the Imjin River that flows through the inter-Korean border swept away a riverside camping site early Sunday morning, killing six people. This tragic incident might have been prevented if the North had given prior notice of the release from its Hwanggang Dam to the South. Investigations are under way to determine the reasons behind the unexpected act. This incident was a man-made disaster not least death of six people. A water level monitoring system(WLMS) of the Imjin River was installed the bridge of Pilseung that operate three public institutions. The WLMS of the A institution set up warning siren and broadcasting as the water level has been rising the bridge of Pilseung in the Imjin River. But the A institution's system was already out of side before discharged of water a dam into the Imjin River and the operators were culpable negligence. The B institution's office employee on charges of negligence that might have contributed to the tragedy and one of the A institution's employees ignored 26 warning messages on the WLMS. This tragic incident was a man-made disaster not least death of six people and might have been prevented if the WLMS was normally operated and the system operators must be worked a tight.
A Study on the Preparation of Thermoplastic Powder Coating Material and Its Flame Retardancy
Lee, Soon-Hong ; Chung, Hwa-Young ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 45~52
The purpose of this study is application to flame retardant powder coating(FRPC) material consisting of ammonium polyphosphate(APP) and magnesium hydroxide(
) as a halogen free flame retardant into thermoplastic resin(LDPE-g-MAH). For improvement of adhesion, LDPE-g-MAH was synthesized from low density polyethylene(LDPE) and maleic anhydride(MAH). The mechanical properties as melt flow index, pencil hardness, cross-hatch adhesion and impact resistance of FRPC were measured. Also, the limited oxygen index(LOI) values were measured 17.3vol%, 31.1vol% and 33.7vol% for LDPE-g-MAH, FRPC-3(APP 15wt%,
15wt%) and FRPC-5(APP 30 wt%), respectively. The thermo gravimetry/differential thermal analysis(TG/DTA) of FPRC-3 was observed endothermic peak at
, it was confirmed predominant thermal stability though the wide temperature range by APP and
. It was showed V-0 grade for FRPC-3 and FRPC-4(APP 20wt%,
10wt%) that a char formation and drip suppressing effect, and combustion time reduced by UL94(vertical burning test). It was confirmed that flame retardancy was improved with the synergy effect because of char formation by APP and
A Study on the Damage of Flame caused by the Vapor Cloud Explosion in LPG Filling Station
Leem, Sa-Hwan ; Huh, Yong-Jeong ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 53~60
LPG(Liquefied Petroleum Gas) vehicles in metropolitan area are being applied to improve air quality and have been proven effective for the reduction of air pollutant. In addition, LPG demand is growing rapidly as an environmentally friendly energy source and its gas station is also increasing every year. Consequently, this study tries to find out the influence of flame caused by the VCE(Vapor Cloud Explosion) in filling station on the adjacent combustibles and people by simulating relevant quantity of TNT. In addition, the damage estimation was conducted by using API regulations. If the scale of the radiation heat is known by calculating the distance of flame influence from the explosion site, the damage from the site can be easily estimated. And the accident damage was estimated by applying the influence on the adjacent structures and people into the PROBIT model. According to the probit analyze, the spot which is 30m away from the flame has 100% of the damage probability by the first-degree burn, 99.2% of the damage probability by the second-degree burn and 93.4% of the death probability by the fire.
An Evaluation of Thermal Stability of Raw Materials in the Vinyl Acetate Polymerization Process
Lee, Keun-Won ; Han, In-Soo ; Lee, Jung-Suk ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 61~65
Most of the chemical reactions performed in the chemical industry are exothermic, meaning that thermal energy is released during the reaction. It is also important to understand the thermal hazards such as thermal stabilities and runaway reactions, which are governed by thermodynamics and reaction kinetics of the mixed materials. The paper was described the evaluation of thermal behavior caused by an exothermic batch process in manufacture of the vinyl acetate resin. The aim of the study was to evaluate the thermal stabilities of raw materials with operating conditions such as a reaction inhibitor, heating rate, reaction atmosphere and the mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed in the differential scanning calorimeter(DSC), C 80 calorimeter, and thermal screening unit(
). It was suggested that we should provide the thermal characteristics for raw materials to present safe precautions with operating conditions in the vinyl acetate polymerization process.
A Study of Ventilation Requirements for Tunnel Considering Recirculation near Tunnel Portals
Rie, Dong-Ho ; Choi, Baek-Yeol ; Yoon, Sung-Wook ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 66~70
This paper analyzes difference between current tunnel ventilation calculation method and advanced one which considers effects of polluted air recirculation near tunnel portals. For the calculation, CFD(Computational fluid dynamics) technique was utilized. From the result, it was found that 4.38% more fresh air is required when there is polluted air recirculation near tunnel portal areas. Hence, it is recommanded that the consideration of polluted air recirculation should be made when deciding the ventilation requirements for tunnel.
Evaluation of Flexural Strength Capacity of Large Scale RC Slabs Strengthened with Prestressed CFRP Plate
Hong, Ki-Nam ; Han, Sang-Hoon ; Lee, Byong-Ro ; Gwon, Yong-Gil ; Woo, Sang-Kyun ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 71~77
This paper presents the results of a study on flexural capacity of large size RC slabs strengthened with carbon fiber reinforced polymer(CFRP) plates. A total of 5 specimens of 6.0m length were tested in four point bending after strengthening them with externally bonded CFRP plates. The CFRP plates were bonded without prestress and with two prestress levels, 0.4% and 0.6% of CFRP plate strain. Test variables included the type of strengthening, prestressing level, and the effects according to each test variables are analysed. The experimental results show that proposed methods can increase significantly the flexural capacity such as strength, stiffness of the beam and the increase ranged between 36.2% and 63.2% of the load-carrying capacity of the control beams. The non-prestressed specimen failed by separation of the plate from the beam due to premature debonding while most of the prestressed specimens failed by CFRP plate fracture. And the cracking loads and maximum loads were increased proportionally to the prestress level.
Making the Insulation Mortar Mixed with Waste Paper and Sawdust
Lee, Seung-Young ; Son, Ki-Sang ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 78~82
This study is to test insulation mortar mixed with wastepaper and sawdust to find out its insulation performance. Therefore, wastepaper and sawdust have been added to normal mortar. They are analyzed for the above purpose using compressive strength and insulation performance. It is found that the more wastepaper and sawdust will be mixed, the lower heat conductivity will be taken. Wastepaper and sawdust mixture will be more 2.0% then the insulation mortar quality can be compatible with the 3rd kind of the standard. Optimal mixture for insulation will be wast paper:sawdust=4:6. Cohesive test of materials showed that test material has stronger than stand are
. It is satisfactory the test result showed a range of
from the test result. Optimal mixture of wastepaper and sawdust have been found out from the study comprehensively, exclusive of the proportion of wastepaper:sawdust = 8:2. It is thought that standard of length deformation; 0.5% is reasonable. This means that deformation of mortar itself can be considered. But it is also Shown that water mixture has also been sharply changed at first flow test. Therefore, it is thought that absorbed water content in the material gave considerable effect to variation rate.
Experimental Performance Verification of Load Carrying Capacity Algorithm of Bridges using Ambient Vibration
Lee, Woo-Sang ; Park, Ki-Tae ; Han, Sung-Ho ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 83~90
In this study, it is conducted that the performance verification of the ambient load carrying capacity algorithm using long-term measurement systems of bridges. For this purpose, a steel-box type model bridge is fabricated and the public load carrying capacity of a steel-box model bridge is estimated by conducting the numerical analysis and load test. In addition, we compare the public load carrying capacity with the estimated result of a steel-box model bridge using the ambient load carrying capacity algorithm. By the assessment result, it is shown that the estimated ambient load carrying capacity is the difference of approximately 6.0 percentages as compared with the public load carrying capacity.
Probabilistic Structural Safety Assessment Considering the Initial Shape and Non-linearity of Steel Cable-Stayed Bridges
Bang, Myung-Seok ; Han, Sung-Ho ; Lee, Woo-Sang ; Lee, Chin-Ok ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 91~99
In this study, the advanced numerical algorithm is developed which can performed the static and dynamic stochastic finite element analysis by considering the effect of uncertainties included in the member stiffness of steel cable-stayed bridges and seismic load. After conducting the linear and nonlinear initial shape analysis, the advanced numerical algorithm is the assessment tool which can performed structural the response analysis considering the static linearity and non-linearity of before or after induced intial tensile force, and examined the reliability assessment more efficiently. The verification of the developed numerical algorithm is evaluated by analyzing the regression analysis and coefficient of correlation using the direct monte carlo simulation. Also, the dynamic response characteristic and coefficient of variation of the steel cable-stayed bridge is calculated by considering the uncertainty of random variables using the developed numerical algorithm. In addition, the quantitative structural safety of the steel cable-stayed bridges is evaluated by conducting the reliability assessment based upon the dynamic stochastic finite element analysis result.
Experimental Study on Seismic Retrofitting Methods for School Building using Aramid Strip
Kim, Hye-Jin ; Park, Tae-Won ; Cho, Seung-Ho ; Lee, Kyung-Koo ; Roh, Young-Sook ; Chung, Lan ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 100~106
Most of the school buildings were built before the seismic code was established. To consider the sunlight and ventilation to the partition walls are built about 1m height beside columns at typical school buildings. For the reason, columns which is consisted school building occur brittle failure shape by the reduced effective depth. In this study, experimental test for retrofitting effect by Aramid Fiber Reinforced Polymers(AFRP) strips on masonry infilled reinforced concrete(RC) frames is performed. The test results were to ensured enough time to evacuate due to the enhancement of ductility and strength of school buildings to withstand earthquakes using AFRP strips.
The Survey of the Current Situation for System Scaffolding in the Domestic Construction Site
Park, Jong-Keun ; Jeong, Se-Gyun ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 107~111
Recently, the domestic construction companies are increasingly using the scaffolding system in order to secure safety although it may increase the construction cost. However since the actual situation of scaffolding system has not been checked yet, no safety standards and work method were made. Hence, various risk factors are involved in the scaffolding system work. Accordingly, this study is intended not only to check the installation/use status of scaffolding system in the domestic construction sites through the in-depth survey and investigation but also to suggest the measures of using the scaffolding system more effectively and systematically while basing the study results.
Driving Safety Analysis for vehicles Against High Wind on the Bridges Using Extreme Value Statistics
Chung, Jee-Seung ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 112~117
This study presents a methodology to evaluate the driving safety of vehicles against localized high wind on the roads over the valleys or along the coasts. Risk level for vehicle accident is derived from the side slip caused by cross wind, and then safety criteria based on reliability for driving stability are defined. The level of safety is classified according to probability of exceeding against wind speed using the concept of extreme value statistics. To attain the safety level of vehicle on bridges, numerical simulations using Computational Fluid Dynamics(CFD) are performed. Based on this result, risk reduction and quality improvement is expected through analysis for each alternative in bridges design, construction and operation & maintenance stage with proposed process
Safety Assessment for Emergency Diesel Generator(EDG) Allowed Outage Time(AOT) Extension using Risk-informed
Lim, Hyuk-Soon ; Kim, Doo-Hyun ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 118~122
In order to provide the necessary operation flexibility during the Nuclear power operation, the extension of existing allowed outage time(AOT) is needed. The extension of AOT affects the Nuclear power plant safety. The validity of changed technical specification requirements should be proved by the safety assessments. In this paper, we evaluated the extension of emergency diesel generator AOT for a single inoperable emergency diesel generator(EDG) from 3days to 7days, 10days and 14days. Finally, the AOT extension contributes the NPP performances through decreasing the unexpected plant trips, reinforcing maintenance and avoiding risks due to unnecessary operation mode changes when the NPP is under the surveillance tests or maintenance.
Influence of Work Difficulty Variation on EEG Characteristics Related with Human Errors
Lim, Hyeon-Kyo ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 123~130
Electroencephalogram(EEG) would be the most objective psychophysiological research technique on human errors though few research has been taken yet. This study aimed to get characteristics of human error while committing simple Odd-Ball tasks by utilizing the power spectrum technique of EEG data. Each experiment was composed of 3 tasks with different rules, and 8 young undergraduate students participated in this study as paid subjects. The result showed in the affirmative that subject and the interaction of subject and task factors were statistically significant on variation of
, and that the former increasing in backward direction to Pz reflects compatibility whereas the latter increasing in forward direction to Fz reflects familiarity. Therefore it was coucluded that, since task 2 carried out in the present research requiring decoding process would be more difficult to human beings than the task merely requiring psychological recall process, task 1 and task 3 were classified into a homogenious group excluding task 2, and the ratio
band power to
band power indicated enormous increase of
band power relative to
band power in the cases of contra-lateral errors, especially in task 2.
Developing the Traffic Accident Severity Models by Vehicle Type
Kim, Kyung-Hwan ; Park, Byung-Ho ;
Journal of the Korean Society of Safety , volume 25, issue 3, 2010, Pages 131~136
This study deals with the accident models of arterial link sections by vehicle type. The objectives are to analyze the characteristics of accidents, and to develop the models by type. In pursuing the above, this study uses the data of 414 accidents occurred on 24 major arterial links in 2007. The main results analyzed are as follows. First, the number of accidents is analyzed to account for about 47% in passenger car, 15% in SUV and 10% in trucks. Second, 3 Poisson regression models which are all statistically significant are developed using passenger car, SUV and truck as dependant variables. Finally, AADT and the number of traffic islands as common variables, and the number of pedestrian crossings, lanes, connecting roads, intersections(4-Leg), rate of medians and the number of bus stops as specific variables of the models are selected.