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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Safety
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Journal DOI :
The Korean Society Safety
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Volume & Issues
Volume 18, Issue 4 - Dec 2003
Volume 18, Issue 3 - Sep 2003
Volume 18, Issue 2 - Jun 2003
Volume 18, Issue 1 - Mar 2003
Selecting the target year
A Study on the Mechanical Properties and Residual Stress Distribution of Ti Welding Material
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 1~7
The objective of this paper was to investigate the welding characteristics according to the restraint condition. the pass number, and the shield gas quantity with titanium commonly using in power stations, aircrafts, ships, and so forth. The residual stress distribution was measured under restraint and nonrestraint welding conditions. The tensile strength and elongation of the 4 pass welded specimen were shown higher about 10% and 30% than those of the 7 pass welded specimen at the same welding conditions respectably. Also, the more shield gas quantity and the shorter natural cooling time, the higher tensile strength and the lower elongation.
Construction of High-Precision Ultrasonics Distance Amplitude Characteristics Curve for Integrity Evaluation of Rail Weld Zone
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 8~13
This study proposes integrity evaluation method of weld zone in rails using high precision distance amplitude characteristics curve(DACC) and ultrasonic signals. For these purposes, the ultrasonic signals for defects(porosity and crack) of weld zone in rails are acquired in the type of time series data and echo strength. 6 lines in the DACC indicated damage evaluation standard of weld zone in rails. The aquired ultrasonic signals agree fairly well with the mesured results of reference block and sensitivity block(defect location, beam propagation distance, echo strength, etc). The proposed high precision DACC in this study can be used for integrity evaluation of weld zone in rails.
An Experimental Study on the Characteristics of Bubbles in Air-Water Model
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 14~18
The structural development of air-water bubble plumes has been measured under different condition on air flow rate in a cylindrical bath. The time-averaged structure of plumes has been measured with an oscilloscope and an electro-conductivity probe. The temperature of bubbles was also obtained by a thermal-infrared camera. Gas volume fraction and bubble frequency were high since bubbles concentrated on the nozzle. In general, their axial and radial values tended to decrease with increasing distance. Bubble temperature reached water temperature within a short time. The present study showed that thermal equilibrium between bubbles and water was completed before bubbles flow became stable.
Free Vibration Analysis of Perforated Rectangular Plates Submerged in Fluid
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 19~27
This paper presented an experimental modal analysis of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the Rayleigh-Ritz method and compared with the experimental results. Good agreement was obtained between the analytical solution and experimental result. The experimental results in water showed that the mode shapes are not sensitive to the depth of submergence. The natural frequencies were shown to decrease drastically once the perforated plates come in contact with water. However, the natural frequencies decrease with the depth of submergence until a certain depth is reached, and become the asymptotic values beyond this depth of submergence. The depth of submergence did not affect the damping ratio greatly.
A Study on Spray Characteristics of Water Mist Nozzle with Mid-low Pressure for Fire Suppression
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 28~32
The present study investigates the spray characteristics of water mist nozzle with mid-low pressure for fire suppression. The examined nozzle types are swirl and spiral nozzle. The result shows that K factor of water mist nozzle is much smaller than those of general sprinkler. Spray angle of spiral nozzle is largest and more than
. SMD(Sauter Mean Diameter) of water mist nozzles is ranged between 100 and 200
through measuring by image processing method. The spray pattern of spiral nozzle represent that water flux of first stream is 2 times larger than that of second stream. This study will contribute better understandings of the water-mist spray characteristics and useful daia for developing the water-mist nozzles.
The Variation of Cooling Charateristics Due to the Weber Number of Droplet
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 33~37
The objective of the present work is to examine the variation of cooling characteristics due to the Weber number of droplet on a heated surface. The surface temperatures varied from 72.5 -
on steel and Teflon, when Weber number was 60, 180, 300. The results are as follows; In the case of the same droplet size, the initial temperature of solid increases the indepth temperature of solid more drop. In the case of the same surface temperature, Weber number increases with increasing the cooling effect of droplet. The time-average heat flux increases with increasing the initial temperature of solid and Weber number. The evaporation time decreases with increasing the initial temperature of solid and Weber number.
High Temperature Fatigue Life and Fractography under Asymmetric Waveform in Strain Control
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 38~43
In this paper, the low cycle fatigue(LCF) life tests were carried out under waveforms of asymmetric triangle(
strain rate) and hold-time(1min and 10min) in strain control. In triangular waveform, the fatigue lives of fast-slow waveforms were decreased to about 63-73% and them of slow-fast waveforms were down to about 23-24% compared to them of fast-fast waveforms. The shapes of fracture surfaces were transgranular in fast-fast and fast-slow waveforms and intergranular in slow-fast ones. The fatigue lives of slow-fast waveforms were remarkedly shorter than them of hold-time waveforms even though cycle times of hold time waveforms were longer than them of slow-fast ones. The damage mechanisms of frature surfaces were mixed frature with both transgranular and intergranular, but intergranular fratures were r-type cavity in hold-time waveforms and w-type cavity in slow-fast ones.
Maximum Torque Control of PMSM Drive in Field weakening Region
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 44~49
Permanent magnet synchronous motor(PMSM) is widely used in many applications such as an electric vehicle. compressor drives of air conditioner and machine tool spindle drives. PMSM drive system have become a popular choice in various application, due to their excellent power to weight ratio. This paper is proposed maximum torque control for field weakening operation of PMSM drive. At low speeds, the reluctance torque is used to maximize the output for a given current level. This is achieved maximum torque per ampere(MTPA) by selecting an optimal value of the direct stator current component. At high speeds, the system reaches a point at which the inverter will not be able to supply the desired voltage. In this case it is necessary to make use of an increased value the direct current component. The proposed control algorithm is applied to PMSM drive system, the operating characteristics controlled by maximum torque control are examined in detail by simulation.
Development of an Intelligent Program for Diagnosis of Electrical Fire Causes
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 50~55
This paper presents an intelligent computer system, which can easily diagnose electrical fire causes, without the help of human experts of electrical fires diagnosis. For this system, a database is built with facts and rules driven from real electrical fires, and an intellectual database system which even a beginner can diagnose fire causes has been developed, named as an Electrical Fire Causes Diagnosis System : EFCDS. The database system has adopted, as an inference engine, a mixed reasoning approach which is constituted with the rule-based reasoning and the case-based reasoning. The system for a reasoning model was implemented using Delphi 3, one of program development tools, and Paradox is used as a database building tool. To verify effectiveness and performance of this newly developed diagnosis system, several simulated fire examples were tested and the causes of fire examples were detected effectively by this system. Additional researches will be needed to decide the minimal significant level of the solution and the weighting level of important factors.
Development of RBI Procedures and Implementation of a Software Based on API Code (III) - Quantitative Approach
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 56~63
During the last decade, effort has been made f3r reducing maintenance cost for aged equipments and ensuring safety, efficiency and profitability of petrochemical and refinery plants. Hence, it was required to develop advanced methods which meet this need. RBI(Risk Based Inspection) methodology is one of the most promising technology satisfying the requirements in the field of integrity management. In this study, a quantitative assessment algorithm fir RBI based on the API 581 code was reconstructed for developing an RBI software. The user-friendly realRBI software is developed with a module for evaluating quantitative risk md financial risk using the potential consequence and the likelihood. Also, inspection planning module for inspection time and inspection method are included in it.
The Method of Consequence Analysis of the Unconfined Vapor Cloud Explosion Accident by the Continuous Release of Gas-Liquid Flow for the Small and Medium Size Enterprises(SMS)
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 64~70
For the unconfined vapor cloud explosion(UVCE) accident by the continuous release of gas-liquid flow of various saturated liquids in a vessel at ground level, overpressures were estimated by TNT equivalency model with two estimation methods, such as UVCE I model based on a constant release time and UVCEII model based on a real travel time of vapor by dispersion and analyzed with various release conditions. As a simulation result the simple, easy, and correct method of evaluation of consequences of the UVCE accident was proposed by using consequences of UVCE I model and correlation equations for differences of overpressures between UVCE models, so that this evaluation method could be used easily in the small and medium size enterprises without using the dispersion model.
A Study on Combustion Property of Oxidizing Solid-Combustible Support Mixtures
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 71~75
The purpose of this study was to review the factors that influence on the combustion experiment of oxidizing solid such as mixing ratio of oxidizing solid and combustible support content ratio of oxidizing solid, ambient temperature, maturing time, combustible support, and additives. The 30g mixing compound samples of oxidizing solid and combustible support were tested with different mixing ratios. As a result, the Infest burning time was measured when mixing ratio was 4 (oxidizing solid) : 1 (combustible support). And the burning time was decreasing as the ambient temperature and maturing time were increasing.
Strength Properties of Waste-tyre Recycling Concrete
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 76~80
There will be a big problem in disposing of waste tie coming from the cars. Because many of these have been thrown away to the field and environmentally polluted. New, We need to find out how to dispose or recycle these waste material. It is thought that recycling this material especially mixing with concrete will be a good idea. This study is focused how each material do its behavior due to the size of waste type particle and its amount into concrete material. 0.4mm-10mm range of particle has been applied to the material : Also, 1.0%, 1.5%, 2.0% range of tyre particle proportion has been applied to make cylinder molds. The concrete mold with waste-tyre particle has vibration-absorbing ability. It is found that 0.4 -0.6mm particle mixing concrete has been more solid organized. And this waste tyre material could be applied to the general concrete, it is found.
Characteristics of Bearing Capacity and Reliability-based Evaluation of Pile-Driving Formulas for H Pile
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 81~88
Recently, pile foundations were constructed in rough or soft ground than ground of well condition thus it is important that prediction of ultimate bearing capacity and calculation of proper safety factor applied pile foundation design. This study were performed to dynamic loading tests for the thirty two piles at four different construction sites and selected pile at three site were performed to static loading tests and then compare with measured value and value of static and dynamic loading tests. The load-settlement curve form the dynamic loading tests by CAPWAP was very similar to the results obtained from the static load tests. Based on dynamic and static loading tests, the reliability of pile-driving formula were analyzed and then suggested with proper safety factor for prediction of allowable bearing capacity in this paper.
The Variation of Sedimentary Rock Strength due to Weathering
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 89~93
The failure of rock slopes were influenced by weathering, which causes change in the shear strength. The weathering is also directly related to slaking and swelling characteristics. In the paper, the core of diameter loom was obtained by digging on rock slope of Kong-ju in Korea and then EDX(Energy Dispersive X-ray spectrometer) analysis was carried out to verified element of chief rock-forming minerals. Uniaxial compression tests, slaking tests, and point load test are performed to study engineering characteristics of conglomerate and red shale. As a results of slaking test, slaking index of conglomerate indicate range of 85.11-99.58 and shale indicate 58.37-99.23. Therefore, it is recognized that the resistance of shale to weathering decreases in shallow depth and it greatly influences the strength of rock. The result of uniaxial compression test and Point load test show that the strength of sedimentary such as conglomerate and red shale has an influence on both weathering and saturation.
A Study on the Cable Length Adjustment of Cable-Stayed Bridges
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 94~100
Generally, cable-stayed bridges are both statically indeterminate structure with a high degree of redundancy and flexible structure. So it is very important to ensure precision control during both fabrication and construction. In precision control of cable-stayed bridges, precision control under multi-objective programming method is needed, because precision control problem of cable-stayed bridges is a multi-objective programming problem in which many objective functions are regard as variables. In previous studies, it was regarded as a single-objective problem, so it had many problems in respect of usefulness and rationalness. In this study, precision control under multi-objective programming method is proposed considering economy, efficiency, and safety at best in precision control of cable-stayed bridges. Precision control problem of cable-stayed bridges is formulated with satisfying trade-off method which is a kind of multi-objective programming method, then it is optimized with min-max method. A computer program is presented including above process.
A Study on Behavior of Rectangular Liquid Storage Structures
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 101~107
Dynamic behavior of flexible rectangular liquid storage structures is analysed by the developed method. The rectangular liquid storage structures are assumed to be fixed to the ground and a moving coordinate system is used. The irrotational motion of invicid and incompressible ideal fluid is represented by two analytic solutions. One is the solution of the fluid motion in the rigid rectangular liquid storage structure due to ground motions and the other is the solution of the fluid motion by the motion of the wall in the flexible rectangular liquid storage structure. The motion of structure is modeled by finite elements. The fluid-structure interaction effect is reflected into the coupled equation of motion as added fluid mass matrix. The free surface sloshing motion and hydrodynamic pressure acting on the wall in the flexible rectangular liquid storage structure due to the horizontal ground motion are obtained by the developed method and verified.
Rating and Lifetime Prediction of a Bridge with Maintenance
Seung-Ie Yang ; Han-Jung Kim ;
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 108~115
Bridges are rated at two levels by either Load Factor Design (LFD) or Allowable Stress Design (ASD). The lower level rating is called Inventory Rating and the upper level rating is called Operating Rating. To maintain bridges effectively, there is an urgent need to assess actual bridge loading carrying capacity and to predict their remaining life from a system reliability viewpoint. The lifetime functions are introduced and explained to predict the time-dependent failure probability. The bridge studied in this paper was built 30 years ago in rural area. For this bridge, the load test and rehabilitation were conducted. The time-dependent system failure probability is predicted with or without rehabilitation. As a case study, an optional rehabilitation is suggested, and fir this rehabilitation, load rating is computed and the time-dependent system failure probability is predicted. Based on rehabilitation costs and extended service lifes, the optimal rehabilitation is suggested.
The Prediction of Failure Probability of Bridges using Monte Carlo Simulation and Lifetime Functions
Seung-Ie Yang ;
Journal of the Korean Society of Safety , volume 18, issue 1, 2003, Pages 116~122
Monte Carlo method is one of the powerful engineering tools especially to solve the complex non-linear problems. The Monte Carlo method gives approximate solution to a variety of mathematical problems by performing statistical sampling experiments on a computer. One of the methods to predict the time dependent failure probability of one of the bridge components or the bridge system is a lifetime function. In this paper, FORTRAN program is developed to predict the failure probability of bridge components or bridge system by using both system reliability and lifetime function. Monte Carlo method is used to generate the parameters of the lifetime function. As a case study, the program is applied to the concrete-steel bridge to predict the failure probability.