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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 14, Issue 4 - Dec 1999
Volume 14, Issue 3 - Sep 1999
Volume 14, Issue 2 - Jun 1999
Volume 14, Issue 1 - Mar 1999
Selecting the target year
A Study for Energy Separation of Vortex Tube Using Air Supply System(II) - the effect of surface insulation -
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 3~9
The vortex tube is a simple device which splits a compressed gas stream into a cold stream and a hot stream without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air supply system. In this study, the insulation effect of surface on the efficiency of vortex tube was performed experimentally. The experiment is carried out for nozzle area ratio of 0.194, diameter ratio of cold end orifice of 0.6 and input pressure ranging from 0.2Mpa to 0.5Mpa. The purpose of this study is focused on the effect of surface insulation of vortex tube with the variation of cold air mass flow ratio. The results indicate that the temperature difference of cold and hot air are higher about 12% and 30% than that of not insulated vortex tube respectively. Furthermore, for the insulated vortex tube, the similarity relation for the prediction of cold end temperature as the function of cold air mass flow ratio and input pressure is obtained.
An Integral Equation of Various Cracks for Safety in Finite Plane Bodies
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 10~18
An integral equation representation of cracks was presented, which differs from well-known "dislocation layer" representation. In this new representation, the integral equation representation of cracks was developed and coupled to the direct boundary-element method for treatment of cracks in finite plane bodies. The method was developed for in-plane(mode I and II) loadings only. In this paper, the method is formulated and applied to various crack problems involving multiple and branch cracks in finite region. The results are compared to exact solutions where available and the method is shown to be very accurate despite of its simplicity.implicity.
Analysis of Thermal Stress of Ceramic-Metal Functionally Gradient Material
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 19~24
A two dimensional thermo elasto-plastic finite clement stress analysis was performed to study stress distributions in functionally gradient material. The upper
surface is heated at 1200K until a steady state is established and cooled at 300K. The influences on the thermal stress distributions due to the difference of compositional gradient exponent p were investigated. In this study, we obtained the thermal stresses are low for p=1.
Evaluation of Fracture Resistance Characteristic for Primary Piping System of Ulchin 3,4 Nuclear Power Plants
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 25~32
The objective of this paper is to evaluate the fracture resistance characteristics of SA508 CL.1a carbon steel, TP347 stainless steel and their associated welds manufactured for primary coolant system of Ulchin 3,4 nuclear power plants. The effect of various parameters such as pipe size, welding method, chemical composition, crack plane orientation, metallography and fractography on the material properties were discussed. Test results showed that the effect of pipe size on fracture toughness is negligible while the effect of welding method on fracture toughness is significant. In addition, the drop of fracture toughness in the field fabrication weld of TP347 stainless steel is probably due to the large amount of
-phase precipitated on the
-ferrite boundary and the large size dimples.
A Study on Stability Hanging Guide Frame used in Floating Crane
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 33~40
In this paper, a damaged example of hanging guide frame used in the lifting of shore protection caisson was investigated. An examination of the stress and stability of members was carried out by structural analysis and the causes of damages was investigated. The stability analysis considering local and global stress buckling was performed. As a result of stability analysis. the first structure was unstable structure. Therefore improved structure was examined and the best effective methodology was the reassignment of wire.
A Study of Strain Waveform Effect on Fatigue Life in High Temperature Low Cycle Fatigue Test
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 41~48
The fatigue life tests were performed in strain control with triangular and hole-time wave-forms at
. The fatigue lifes were investigated according to waveform examining damage mechanisms, which could be used to predict the fatigue life and estimate the remaining life. The results obtained are as follows; The fatigue lifes were in order of the fast-fast>the fast-slow>the slow-fast in the triangular waveforms, and the fatigue lifes in slow-fast waveforms got shorter in the hold-time waveforms. The damage mechanisms of the fracture surfaces were transgranular fracture in the fast-fast, the fast-slow waveforms and intergranular fracture in the slow-fast waveform.
A Study on the Cut Off Characteristics and Graphite Analysis of Residual Current Protective Devices for Low Voltage
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 49~54
In this paper. we studied cut off characteristics and fire hazard of residual current protective devices(RCD or ELB) for low voltage. The operative time of RCD with grounding resistance was analyzed by using RCD operating tester. The surface structure and composition of insulator were analyzed by using scanning electron microscope(SEM) and energy dispersive x-ray spectroscopy(EDX). The surface of phenol resin showed network structure and void. The spectra shown in EDX analysis are composed not only of the corresponding elements but also of several new spectra, as CK. OK
. MgK, SiK. and CaK, which were absent in original material.
Fuzzy Control for Performance Improvement of DC Motor Drive System
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 55~65
Fuzzy logic fuzzy set theory is recently getting increasing emphasis in process control applications. This paper describes application of fuzzy logic in a speed control system that uses a phase controlled bridge converter and a separately excited dc motor. The fuzzy control is used to linearize the transfer characteristics of the converter in discontinuous conduction mod occurring at light load and high speed. The fuzzy control is then extended to the current and speed control loops replacing the conventional PI control method. The control algorithms have been developed in detail and verified by simulation of a DC motor(DM) drive system. The simulation result indicates the superiority of fuzzy control over the conventional control methods. Fuzzy logic seems to have a lot of promise in the applications of power electronics.
A Study on the Improvement of Water-Leakage Detection Reliability in Local Heating System
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 66~72
Local heating transportation pipe has sensor and return lines to detect water-leakage. There are impulse and resistance comparison measurement types for a water-leakage detection. The impulse type shows large detection error within a measurement range. Since the resistance comparison type can find a comparative accurate single water-leakage point in the measurement range of heating pipe, it has been used to detect water-leakages these days. However if the multi water-leakages are happened in the measurement range of transportation pipe. the resistance comparison type shows a detection error point by the parallel resistance between a detection sensor line and ground. But the detection error will be minimized by the divided transportation pipe loops. In this research, it suggests the design of remote controlled detection system which can divide a large pipe loop and a possible single water-leakage measurement process in each divided loops.
by Plasma Discharge
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 73~77
In this study,
reduction have been investigated by using coil type plasma reactor. The experiments have been carried out changing discharge power, gas flow rate frequency and electrode style to obtain the decomposition rate. Decomposition rates of
were obtained 20~98% at gas flow rate 100ml/min~1,000ml/min and discharge power 5~25w respectively. The energy efficiency is very good at the high frequency power. The decomposition rate of
for 5kHz power supply is only 90%, but for 10kHz power supply is very high, more than 98% for 15w. The decomposition rate is increasing according to the residence time or the power consumption of the discharge. About 15W discharge power for 17
reactor is necessary to obtain the decomposition rate of
of more than 85% or 98%. From these experiments, the consumption power of the decomposition rate of 98% in 300ppm
gas in nitrogen gas proved to be 18W and 300ppm
gas to be 15w.
The Characteristics of Desulfurization for Dry-Type High Temperature in a Fluidized Bed Reactor
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 78~85
The removal characteristics of H
S from IGCC process over the natural manganese ore(NMO) containing several metal oxides(
: 3.86%, CaO : 0.11%) were carried out in a batch type fluidized bed reactor(I.D.=40mm, height=0.8m). The
breakthrough curves were obtained as a function of temperature, initial gas velocity, initial gas concentration, and aspect ratio. The effect of particle size ratio and particle mixing fraction on
removal were investigated with binary system of different particle size. From this study, the adsorption capacity of
increased with temperature but decreased with excess gas velocity. The breakthrough time for
is reduced as the gas velocity is increased which leaded to gas by-passing and gas-solid contacting in a fluidized bed reactor. The results of the binary particle system with different size in batch experimental could predict to improve the behavior of continuous process of
removal efficiency. The natural manganese ore could be considered as potential sorbent in
Chemical Cleaning of Copper Corrosion Product Using EDTA.2Na Salt and Effect of Surface Treatment by NALCO-39L
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 86~92
This study was carried out to investigate the effect of chemical cleaning of corrosion product on cooling system made of copper as a basic material and using cooling water as pure water. We studied chemical cleaning condition that minimizes the influence on basic material by means of EDTA solution so as to eliminate the slurry in cooling system. In addition, the proper amount of NALCO-39L (Nitrite-Borate-BZT mixture) as a inhibitor was determined in order to protect the copper in cooling system against corrosion after chemical cleaning and the effect of corrosion resistance on the copper surface treated was excelent in comparison with surface untreated. As a result, we found that the main components of sludge in cooling system produced by corrosion of copper were
, CuO, Cu, and Fe. The optimum condition of chemical cleaning was 400ppm EDTA solution at
. Inhibitor concentration needed to treat the surface of pure copper was 15～20ppm per unit area and corrosion rate of copper treated with 500ppm inhibitor solution for 72 hrs at
was remarkably decreased as compared with that of pure copper.
A Study on Explosive Limits of Flammable Materials - Prediction of Explosive Properties and Temperature Dependence of Explosive Limits for n-Alcohols -
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 93~100
By using literature data, the empirical equations have been derived which describe the interrelationships of explosion and other related properties of n-alcohols. The properties which have been correlated data are : lower and upper explosive limits, heats of combustion, carbon numbers. Also, the new equation for predicting the temperature dependence of lower explosive limits(LEL) of n-alcohols on the basis of explosive limits, heats of combustion, flame propagation theory and mathematical method is proposed. The values calculated by the proposed equations were a good agreement with literature data within a few percent. From a given explosive properties. by using the proposed equations, it is possible to predict the other properties. It is hoped eventually that this method will permit the estimation of the explosive properties of alcohol with improved accuracy and the broader application for other compounds.
by Sol-Gel Method and Their Photocatalytic Activities
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 101~107
system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area was measured. Considering the efficiency of the ethanol decomposition using the catalyst, the conclusion was made as follows: 1) By means of X-ray analysis of
powder that is obtained from water and Titanium alkoxide with various molar ratios, it is shown that structure of crystallization is a dominating structure and, on the other hand, the crystallization of rutile also partly exists. The specific surface area is at its maximum value at R=6, which is the molar ratio of water vs. alkoxide, whereas its value goes down as the molar ratio increases. In the reaction of using
catalyst, the ethanol is decomposed into the extent of 15 ~30% in an hour and three hours are necessitated for 70% decomposition. 2)
powder is developed from Titanium and Silicon alkoxide by a hetero-condensation process. The increase of SiO
contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. In the decomposition reaction of the ethanol, the decomposition efficiency represents 25~60% in an hour. It is, however, examined that the efficiency inactively increases corresponding to the duration of reaction time. It is shown that more than 90% of ethanol is decomposed when reaction time is about three hours and the efficiency illustrates the maximum value for 60-
Fracture Characteristics of Stainless Steel Under Low Temperature Conditions
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 108~115
It has been recognized that the mechanical properties of structural steels can be accepted very greatly in a state of normal temperature. While, under low temperature conditions the properties of the structural steels may not be appropriately achieved. When the various and particular structures will be constructed in an intense cold region afterward, the mechanical properties of a stainless steel under low temperature condition must be investigated. The purpose of this paper is to account for the fracture mechanics of structures in the state of low temperatures. The fracture toughness was examined through an experimental test from which the tensile strength and impact values of STS 304 were obtained. In order to demonstrate the present studies, the fracture toughness was compared with the test results for SWS 50 published previously by an author.
Quantifying Praitical Application for Specialized Course on Temporary Work Safety
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 116~123
It is generally considered that only questionnares, collected at the time when each course close, have been evaluated & represented for all of the subjects. But all the result of each course can be actually evaluated using only the data taken from how to apply for at the construction site or at the factory, directly, for the period of at least one year, not just short months. This study is to evaluate and quantify the result and analyses using the data from questionnare concerning the level practically applied to each process at construction site. 1st for three(3) months, 2nd for six(6) months, 3rd for nine(9) months, finally 4th for twelve (12) months, one year These questionnares have been distributed for same people four(4) times to find out what to, how to be applied with each subject.
The Effect of W/C Ratio and Chloride on Compressive Strength of Concrete Exposed to High-temperature
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 124~128
Product background of cement, sand and coarse aggregate differ from country to country, so that thermal behaviour of concrete make a difference in high temperature. To cope with demand, this paper is a study on compressive strength for W/C 45%, 55% and 65% by using domestic portland cement, Han-river sand, sea sand and crushed-coarse aggregate. As a result, it is shown that it is estimating to the mechanical properties of heated concrete specimens under various W/C ratio.
A Study on the Flexural and Shear Behavior of Repaired and Rehabilitated RC Beams
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 129~140
This study presents test results of RC beams strengthened by steel plates, carbon fiber sheets(CFS) and aramid fiber sheets(AFS) for increasing flexural and shear resistance. The test was performed with different parameters including the type of strengthening materials, flexural-strengthening methods and shear-strengthening methods. In case of flexural test, RC beams are initially loaded to 70% of the ultimate flexural capacity and in case of shear test loaded to 60 or 80 percent of the ultimate shear capacity and subsequently reinforced with steel plates, CFS and AFS. Experimental data on strength, steel strain, deflection, and mode of failure of the reinforced beams were obtained, and comparisons between the different shear reinforced schemes and the non-strengthened control beams were made. The test results showed that damaged RC beams strengthened by steel plates, CFS and AFS have more improved the flexural and shear capacity. For the beams with external reinforcement by steel plates, aramid fiber sheets and carbon fiber sheets increases in ultimate strength of 4 to 21, 17 to 43 and 26 to 36 percent were respectively achieved. Initial load had small effect on strength after reinforcement, but an important influence on deflection. One sheet reinforced was stronger than two sheets reinforced but less deflected than two sheets reinforced.
A Study on Industrial Accident Cases by an Application of Correlation Analysis
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 141~149
At present time, industrial accidents statistics are used as the basic data of the policy to prevent industrial accidents and the plan to applicate the industrial accident insurance. But this statistical data is not sufficient for the effective safety management because it is the expression of the itemized distribution and the frequency for the whole cases. This study tried to correlational analysis for each causes by defining investigational items as their accident parameters. The correlational analysis, between the unsafe action and status and their relational causes, was performed to analyze the occurrence causes of industrial accident. And to assume the severity of accident, the correlativity and independency between causes and direct causes which are defined hospital days subordinate parameter were analyzed. In addition, this study expressed numerically the effectiveness of subordinate parameters depended on the level of independent parameter by presenting the predictive model between dependent parameter and independent parameter, which have the categorical parameter, through the Logit analysis method.
Analysis of Human Factors Involved in Construction Projects by Accident Types Approach
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 150~157
Developed in the study is the analysis of human factors involved in accidents of Korean Construction Projects. The 556 cases are sampled from a survey material 'Serious Accident Cases in the Construction Projects' edited by Korea Industrial Safety Corporation in 1995 through 1997. The analysis of these cases shows that existing classification system is not good for practical applications in real spots since they are difficult for engineers to understand. In this paper, human factors are classified into three groups by extracting the analysis and arrangement of the cases. Futhermore, We'll propose here a new type of accident which is subdivided. If engineers use this type of accident, they will be probably able to analyze efficiently human factors which are involved in accidents and relatied with how it happen. In the case of fall and upset accidents, personal factors seem to be critical when workers are horizontally moving in an unstable manner, and vertically moving without boarding facilities. Futhermore work environmental factors are important when workers release some materials and are performing building and dismantling tasks.
A Study on Safety Management Model of Shipyard Industry Subcontractor
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 158~166
Due to the work characteristics of shipyard industry, subcontractors are essential and employees of them consist of 25% of the total employee. Problems of their safety management are as follows; - obscurity of safety management responsibility - flimsiness of subcontractor's safety awareness - absence of ability to develop safety techniques and to provide safety equipments - lack of opportunity of safety education The purpose of this study is modelling safety management system of shipyard industry subcontractors to reduce industrial accidents by employees of subcontractors. A phased model contained organization and work responsibility of related departments, safety management planning and evaluation system, safe work supporting system, safety education supporting system.
Reasoning Model of the Case-Based Construction Safety Management System
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 167~176
Construction accidents occur reiteratively in similar fashions. There have been several attempts to develop a safety program for preventing construction accidents on sites. It will be very effective to use previous accident cases for establishing proper safety plan and managing safety process. This research develops a case-based construction safety management system which enables construction managers or safety managers to prevent potential accidents during the construction process. The case-oriented approach is performed through the representation of previous accident cases in accordant with the similarity to the conditions of current site. It uses a case-based reasoning which is one of the reasoning methods of an expert system. A prototype system for the reasoning model was implemented using one of the case based system development tools. The system was applied to a real construction site to verify its capability and validity. It was founded that the causes of accidents were successfully removed, so the proposed model proved to be reasonable. Additional research is needed to resolve the technical problem how to adapt the countermeasures for accident prevention provided by the reasoning model.
Analysis of Initiating Event Frequencies for PSA Based on the Unexpected Reactor Trip Events in KOREA
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 177~184
PSA(Probabilistic Safety Assessment) methodology is widely used on assessing the safety of Nuclear Power Plants(NPPs) quantitatively in the domestic nuclear field. Initiating event frequencies are absolutely needed to conduct PSA, and they considerably affect PSA results. There is no domestic database where domestic trip event cases are reflected, so they are used to assess the safety of NPPs that are from the foreign database. In this paper, operating experience data from the Korean NPPs was collected and analyzed for the trip event cases, which are necessary to determine the initiating events and their frequencies. Korean NPPs have experienced five of 16 initiating events, which we LOFW. LOCV, LOCCW, LOOP and GTRN as a result of analyzing the trip event cases. Initiating frequencies based on the domestic trip event cases are analyzed, and they are similar to that from the foreign database.
Body Discomfort and CTS Survey for Korean Dentists in Accordance with Clinic Activity
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 185~192
The purpose of this study is to investigate the physical disorders of CTDs prevalent among dentists who are exposed to job risk factors. The average total work time per week of subjects(N=117) was 44
6 hours, work time with one patient was 20
10 minutes, and their daily tasks were consisted of extraction, filling, preparation, nerve amputation of tooth. The results of this study are as follows: 1) The discomfort test shows that dentists suffer from discomfort/pain in upper extremities. 2) The work environment test related to CTDs shows that female dentists feel more uncomfortable in the height of chairs than male dentists. 3) The symptom test shows that female dentists suffer from more pain in fingers or wrists at night than male dentists.
A Study on the Investigation of Safety Management System for Venture Business
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 193~198
The venture businesses deal with various kinds of hazard factors, that is, substances, processes and techniques, which have not been investigated. Nevertheless, the safety management systems of venture businesses are not systematic until now. And also it is very difficult to find out the cases of foreign advanced countries. In this study a questionnaire which investigate the present states of safety management system, have been excuted for 358 venture businesses. As a result, the present states of safety management system of venture business are assessmented, and the supporting direction of the safety management for venture business is proposed.
Vibration Analysis of Curved Beams Using Differential Quadrature
Ki-Jun Kang ;
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 199~207
The differential quadrature method (DQM) is applied to computation of eigenvalues of the equations of motion governing the free in-plane and out-of-plane vibrations for circular curved beams. Fundamental frequencies are calculated for the members with various end conditions and opening angles. The results are compared with existing exact solutions and numerical solutions by other methods (Rayleigh-Ritz, Galerkin or FEM) for cases in which they are available. The differential quadrature method gives good accuracy even when only a limited number of grid points is used.
Elevated Temperature Creep Behavior of Rapidly Solidified Al-9.45wt%Fe-4.45wt%Cr Alloy
J.K. Rhim ; K.H. Kim ; T.S. Kim ;
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 208~215
The creep behavior of a rapidly solidified and consolidated Al-9.45wt%Fe-4.45wt%Cr alloy were investigated in the stress range 40 to 115 MPa and temperature range 300(0.53Tm) to 441
(0.66Tm). It is of use to available aerospace and automobile industries for the improved performance of materials used at high temperature. Because Al alloys with improved creep resistance offer the potential for lower weight and reduced costs in aerospace and automobile components (e.g., structural members and engine parts) through the replacement of heavier and more costly materials, the safety in use at high temperature is good. The alloy is characterized by high stress exponents and activation energies for creep, which are greatly dependent on the stress and temperature. Because the creep stress is seen to cause a strongly significant enhancement of coarsening, the coarsening rate of the dispersed particles in all crept specimens is faster than that in isothermally annealed specimens. Dislocations connecting dispersoids are observed more cofrequently in crept specimens with higher stress and lower temperature. The creep strain rates in the power law creep regime were found to be predicted much better by the Shorty and Rosler/Arzt equation with the inclusion of a threshold stress and dislocation detachment mechanism. The dispersoids in this alloy were acting a source of void nucleation that finally leaded to ductile fracture within the grain so called intergranular. Each void was initiated, grown and failed at the dispersoids in the aluminium matrix. Grain boundary accommodation of the slip produced, which result in initiation of the void and then final transgranular fracture. Therefore, it was confirmed that these dispersoids played an important role in the fracture mechanism by the formation of
Electrical Pulses of Internal Partial Discharges Accompanying with Electrical Tree in LDPE
S.H. Kang ; Y.G. Park ; S.S. Kwon ; T.S. Shin ; K.J. Lim ;
Journal of the Korean Society of Safety , volume 14, issue 1, 1999, Pages 216~221
The correlation between propagation of electrical tree and internal partial discharges is discussed. We use specimens with needle-plane electrode system made of LDPE(Low Density Polyethylene), observed inception and propagation of electrical tree by optical microscope and investigated the characteristics of the partial discharge (PD) pulses accompanying with propagation of electrical tree. In the specimens with needle-shaped void, the tree propagates branch type. The length of the tree has good linear relation with average discharge power of PD pulses. In the specimens without needle-shaped void, the tree grows bush type tree. The correlation between the area of the tree and the average discharge power of PD pulses has linear relation.