Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society of Safety
Journal Basic Information
Journal DOI :
The Korean Society Safety
Editor in Chief :
Volume & Issues
Volume 12, Issue 4 - Dec 1997
Volume 12, Issue 3 - Sep 1997
Volume 12, Issue 2 - Jun 1997
Volume 12, Issue 1 - Mar 1997
Selecting the target year
New Approaches to Flaw Classification and Sizing for Quantitative Ultrasonic Testing
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 3~16
In modern high performance engineering applications, the structural integrity of materials and structures are quite often evaluated using fracture mechanics. This evaluation in turn requires information on the flaw geometry (location, type, shape, size, and orientation). The ultrasonic nondestructive evaluation (NDE) method is one technique that is commonly used to provide such information. Flaw classification (determination of the flaw type ) and flaw sizing (prediction of the flaw shape, orientation and sizing parameters) are very important issues for quantitative ultrasonic NDE. In this paper new approaches to both classification and sizing of flaws are described together with extensive review of previous works on both topics. In the area of flaw classification, a methodology is developed which can solve classification problems using probabilistic neural networks, and in the area of flaw sizing, a time-of-flight equivalent (TOFE) sizing method is presented. The techniques proposed here are in a form that can be used directly in many practical applications to quantitative estimates of the flaw's significance.
A Study on Parameter Sensitivity Study of Crack Opening Ratio by Using Numerical Calculation
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 17~21
The fatigue crack propagation rate has so far been measured by the effective stress intensity factor range Δ K/sub eff/. But no research has been done to study how much the crack opening ratio influences the expectation of the fatigue crack propagation. Therefore, this paper evaluates of the crack opening ratio on the fatigue crack propagation life by using the method of parameter sensitivity study. Summarizing the result ; ( 1 ) When the crack opening ratio U' is high, the effect of U' gets larger than any other except for the material factor m. But when U' is low, the effect is also diminished. Therefore, the selection of the lowest value possible is desirable in the evaluation of life. (2) When the value of the material factor m is high, the effect of crack opening ratio U' is increased, at the same time the effect of the other parameters also increased wholly. The effect of material factor m itself on life is high, but in case the material factor m is high, that the effect of each parameter on life get higher is unique. In designing, better attention to the material selection should be drawn. (3) In case the stress ratio R gets smaller, the effect of crack opening ratio U' is unchangeable. But the effect of R itself remarkably decreases, and the effect of material factor m somewhat decreases.
Development of a Forced-Vortex Oil-Water Separator
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 22~26
A small scale centrifugal oil separator consisted of two concentric tubes was fabricated for spilt oil recovery. With speed control of the inner tube, its performance of oil separation was investigated. Oil-water mixture is separated by forced vortex motion with the rotating inner tube. Velocity and pressure distributions in the tubes were calculated. Control of rotating speed, which is the most influencing parameter, showed an optimum value 946rpm corresponding to the acceleration of 20g at the inner tube surface. Separation performance was suddenly deteriorated at rotating speed higher than 1200rpm.
Influence of Hygrothermals on Residual Fatigue Bending Strength of CFRP Composite Laminates
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 27~36
This paper evaluates the static and fatigue bending strengths of CFRP (carbon fiber reinforced plastic) laminates subjected to hygrothermals. The specimens which had different stacking composition, orthotropic and quasi-isotropic laminated plates, were prepared for this experiment. A steel ball launched by the air gun collides against CFRP laminates to generate impact damages, and the 3-point fatigue bending test is carried out by using the impacted laminates to investigate the influence of hygrothermals on the effect on the residual bending fatigue strength of CFRP laminates.
A Study on the Vibration Characteristics of Laminated Composite Rectangular Plate using ANSYS
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 37~44
Composite materials have various complicated characteristics depending on the ply materials, ply orientations, ply stacking sequences and boundary conditions. Therefore, it is difficult to analyze composite materials. For efficient use of composite materials in engineering applications, the dynamic behavior such as natural frequencies and nodal patterns should be identified. This study presents FEM results for the free vibration of symmetrically and antisymmetrically laminated composite and hybrid composite rectangular plates. The natural frequencies of laminated composite rectangular plates having the various boundary conditions (completely clamped, 2-edge clamped, cantilevered) are experimentally obtained. In order to demonstrate the validity of the experiment, FEM analysis using ANSYS was performed and natural frequencies experimentally obtained is compared with that calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.
A Study on Elevated Temperature Fracture Behavior of Cracks in 1Cr-0.5Mo Steel Weld
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 45~56
Fracture behavior of ex-serviced 1Cr-0.5Mo steel was measured at room(
) and elevated(
) temperature and compared with that measured with virgin 1Cr-0.5Mo steel. Compact C(T) specimens were machined from the base and welded test materials. In case of the C(T) specimens of the weld, fatigue precrack was introduced along the fusion line so that following crack growth should occurs along the region of heat affected zone. It was observed that the J-R curve of the serviced material was significantly lower than that of the virgin material at room temperature. Brittle fracture was observed in the serviced material. On the other hand, at elevated temperature no noticeable difference was found between the J-R curves of the virgin and the serviced material. The measured J-R curves were also compared with those of the 1.25Cr-0.5Mo steel obtained from the other literatures. Optical microscopy and SEM examination of the serviced material reveal the carbide in/along the grain boundary which shows material degradation due to long-term usage. An example of application of the measured J-R curves is shown.
Fatigue Crack Propagation Behavior for Electron Beam Welded Joint of SUS 321
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 57~64
Fatigue crack propagation behaviors and life prediction for SUS 321 plate and its electron beam weld metal were investigated using compact tension specimens. The larger the stress ratio is, the faster the crack propagates, but the variation of crack propagation rate decreases. The effect of stress ratio is greater in the slow crack propagation area than in the faster one. The crack propagation rate of electron beam weld metal is faster than that of base metal because of hardening, weld defect and residual stress in welding area. The crack propagation rate of transverse weld metal has a lower than that of base metal due to the effect of residual stress, but in the time of passing through welding area, has a higher rate. The crack propagation rate using
can be well plotted regardless of stress ratio. The fatigue life prediction method of considering crack closure more exactly predicts fatigue life than conventional one. conventional one.e.
The Characteristics of Potential Decay on the Corona Electrified Composite Insulating Material by Surface Condition
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 65~69
Especially, Fiber glass Reinforced Plastics(FRP) is the best composite insulating material which has been so far. Therefore, it's worthy of notice to investigate on the corona electrified composite insulating material by surface condition. And then some other materials will be focussed on. In this study, charge decay were measured with charging-time and grid voltage on FRP composite material surface in order to analyze the mechanism. As a result we have studied that the way of the composite glass fiber(GF) and Polymer and the condition of the contaminated surface was different. In case of the GF is mixed with vertical, charge decay speed is fast because the charge is easily leaked. On the other hand, the surface charge decay speed is depend on conductive or insulated of the contaminant.
Fuzzy Linguistic Variable Based Approach for Safety Assessment of Human Body in ELF Electromagnetic Field Considering Power System States
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 70~79
This paper presents a study on the fuzzy linguistic variable based approach for safety assessment of human body in ELF electromagnetic field considering power system states. To cope with the demand in modern industry, the power system becomes larger in scale, higher in voltage. The advent of high voltage system has increased the relative importance of field effects. The analysis of ELF electromagnetic field based on Quasi-Static Method is introduced while the power system is included to model the expected and/or unexpected uncertainty caused by the load fluctuation and parameter changes. In order to analyze the power system, Monte Carlo simulation method and contingency analysis method are adopted in normal state and alert state, respectively. In the safety assessment of human body, the approach based on fuzzy linguistic variable is employed to overcome the shortcomings resulting from a crisp set concept. The suggested scheme is applied to a sample system(modified IEEE 14 bus system) to validate the usefulness.
A Design of a Screen Monitoring Controller for the Electric Furnace Temperature Control
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 80~86
In this paper, a temperature controller with monitor function is proposed for the electric furnace system. This controller includes holding and ramp control function, and the control program for the temperature process monitor of the electric furnace. For this purpose, the implementation and performance of auto tuning algorithms in a computer-based controller was studied in relation to the control of nonlinear electric furnace system which is characterized with large delay time. The control program for this controller programmed by c-language. To communicate a control and detection signals, between the controller and the electric furnace is implemented by the I/O data card. We apply the temperature controller to the practical electric furnace. As a result, the proposed controller shows the better status characteristic.
A Study of Thermal Stability on Polymers and Sodium Azide Mixture by DSC
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 87~94
If sodium azide is impinged by certain reasons, it will be produced explosives by heavy metals and toxic materials. But it is used propellent for inflating automotive safety bags and the other chemical manufacturing purpose. The investigation of thermal hazard potential of sodium azide itself and with polymers ate very important because some parts of automotives, transporting vessels of reactive chemicals and many any other constituents of structures in factories are made of polymers. The range of decomposition temperatures are about
, even if it depends on heating rate and sample weight. Thermal decomposition heat of sodium azide in air is higher than in nitrogen atmosphere, because the former is included oxidizing heats of sodium metal which is made by decomposition of sodium azide to end. Especially decomposition temperature of polymers are increased on the order of bonding energy between atoms in hydrocarbon moleculars.
An Experimental Study of
Reduction Using PPCP
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 95~101
The confidence of new technology development for
components elimination is obtained as conclusion based 1ike followings ; 1) The technology using PSC spark is a excellent methods for
components elimination above 70% without by-product pollutants. 2) Some materials like Oxygen, Vaporized Water and Ammonia, increase the of
elimination by staged addition. 3) Environmental conditions like pulse frequency and peak voltage are the important dosing factors for pollutants elimination effects. 4) As the PSC technic is the up-to-date one for pollutions elimination the research and development must be executed continuously for the purpose of theoretical establishment. And the application field must be broaden in future.
Optimization of In-Line Dry Scrubbing FGD process using Calcium Hydroxide and Effect of Additives
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 102~111
An In-line dry scrubbing FGD process was investigated. Calcium hydroxide was entrained in flue gas and the SO
removal efficiency by humidity and additives were examined. The range of reaction temperature was
and the concentration of
was around 900ppm. By the increase of humidity in flue gas, the removal efficiency was increased. The effect of NaOH as a additive was very high and got high conversion of
, however in case of RH 90%, it was reverse. The effect of particle size and flow rate were examined. And the reaction rate constant and effective diffusivity also calculated.
Analysis of Defluidization Using Pessure Fluctuation Properties in a Fuidized Bed Combustor
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 111~118
Granulation procedure was carried out in a 0.109m I. D., 1.8m height fluidized bed coal combustor of the multi-sized particles. The domestic anthracite with heating value 3240kcal/kg was used. Granulation of fine coal particles and fluidizing characteristics were investigated by the pressure fluctuation properties such as mean pressure, standard deviation of pressure fluctuation and power spectrum distribution. Defluidization state and granulation mechanism were also studied by the various analysis. It was found that the conversion efficiency in the elutriated stream was increased by the coalescence of fine coal particles. Defluidization and pressure fluctuation properties were interrelated and this result was indication of the capabilities of pressure fluctuation properties analysis in the diagnostics of fluidizing state.
A Study on the improvement of working condition in the downtown Underground construction - Focused on the Ventilation and Lighting -
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 119~132
According to the construction environmental changes due to the trend of large scale and complicated building construction, many construction methods(such as : TOPDOWN )are more often used. However, it is pointed out that occupational pulmonary diseases, reduction of the machinery lifetime and productivity caused to be narrow visual field and collision between the workers. Therefore, this study is mainly dealing with the views of productivity and safety improvement in order to improve work efficiency and to insure the safety in underground construction environment.
Effect of S.E.C Mixing on the Properties of Concrete
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 133~139
Conventional concrete mixing method is to put all of the materials simultaneously into a mixer and mix for a required time. However, recently concrete researchers have reported that mixing sequence iufluences the properties of concrete. This study discusses the influence of mixing sequence and partitioning addition of mixing water. Concrete, by method of partitioning addition of mixing water, was found to have substantially stronger strength than conventional concrete with the same water-cement ratio. This means that a higher strength concrete could be obtained by using “Sand Enveloped with Cement”(S.E.C) mixing technique. Both a high bond strength between cement paste and aggregate, and elimination of bleeding both contribute to improving the strength of S. E. C concrete.
Behaviour of Concrete Building with High Temperature
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 140~145
The main purpose of this study is to establish the reliable method for evaluating fire damage of reinforced concrete building, by using the rational procedure, and to develope the rehabilitation methods of fire damaged concrete structures. Especially, this proposed evaluation method is applied to the fire damaged concrete buildings of domestic, and the rehabilitation methods on the basis of these applied results are proposed and those example are shown. The proposed rational evaluation method for fire damaged concrete building proceeds is estimating the reduction of the mechanical properties of concrete of fire damaged structural members in comparison with the experimental results which are obtained from the compression tests of heated concrete specimens under various temperatures.
Human Workers' Stability-Maintaining Capabilities on A Tiltable Stability Platform
Journal of the Korean Society of Safety , volume 12, issue 2, 1997, Pages 146~152
The number of accidents due to slipping, falling and awkward postures are estimated to account for over forty percent of annual industrial accidents in Korea. To prevent such accidents, stability-maintaining capabilities of workers should be understood before any other approach. This research was aimed to analyze capabilities of the workers with the help of yours male students maintaining standing postures on a tiltable stability platform. The experimental result showed that tilting direction, height of pivoting point, and permissible degree of swaying made significant effects on stability-maintaining duration. Besides, humans are more capable of maintaining their standing body postures on a platform tiltable fore and aft rather than or one tiltable sideways. The number of falling or tripping supported this phenomenon. A mechanical and physical discussion on the stability was added.